[Federal Register Volume 60, Number 245 (Thursday, December 21, 1995)]
[Proposed Rules]
[Pages 66344-66469]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 95-29458]




[[Page 66343]]

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Part II





Environmental Protection Agency





_______________________________________________________________________



40 CFR Parts 260, 261, 266, and 268



_______________________________________________________________________



Hazardous Waste: Identification and Listing; Proposed Rule

  Federal Register / Vol. 60, No. 245 / Thursday, December 21, 1995 / 
Proposed Rules   

[[Page 66344]]


ENVIRONMENTAL PROTECTION AGENCY

40 CFR Parts 260, 261, 266, and 268

[FRL-5337-9]
RIN 2050-AE07


Hazardous Waste Management System: Identification and Listing of 
Hazardous Waste: Hazardous Waste Identification Rule (HWIR)

AGENCY: Environmental Protection Agency.

ACTION: Proposed rule, tentative response to Chemical Manufacturers 
Association petition and the Hazardous Waste Identification Dialogue 
Committee recommendations, and request for comments.

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SUMMARY: The Environmental Protection Agency (EPA) today is proposing 
to amend its regulations under the Resource Conservation and Recovery 
Act (RCRA) by establishing constituent-specific exit levels for low-
risk solid wastes that are designated as hazardous because they are 
listed, or have been mixed with, derived from, or contain listed 
hazardous wastes. Under this proposal, generators of listed hazardous 
wastes that meet the self-implementing exit levels would no longer be 
subject to the hazardous waste management system under Subtitle C of 
RCRA as listed hazardous wastes. Today's Notice, commonly referred to 
as the Hazardous Waste Identification Rule (HWIR), establishes a risk-
based ``floor'' to hazardous waste listings that will encourage 
pollution prevention, waste minimization, and the development of 
innovative waste treatment technologies.
    Many of the exit levels are established using an innovative risk 
assessment which evaluates potential exposure pathways, both direct and 
indirect, from a variety of sources, such as waste piles and surface 
impoundments. This assessment focuses on both human and environmental 
receptors and is presented for comment in today's Notice. The remaining 
exit levels are based on an alternative risk analysis.
    The Agency is also proposing to modify some of the land disposal 
restriction (LDR) numerical treatment standards listed in subpart D of 
40 CFR part 268. This notice proposes to cap technology-based treatment 
standards with the risk-based exit levels which minimize threats to 
human health and the environment. This notice also takes comment on 
several general approaches and one specific approach for conditional 
exemptions from subtitle C management. Today's notice also contains the 
Agency's tentative response to a petition for rulemaking submitted by 
the Chemical Manufacturers Association and the Agency's tentative 
response to the recommendations made by the Dialogue Committee on 
Hazardous Waste Identification. This committee was formally chartered 
in July 1993 in accordance with the Federal Advisory Committee Act 
(FACA).

DATES: EPA will accept public comments on this proposed rule until 
February 20, 1996. Comments postmarked after this date may not be 
considered. However, the Agency recognizes that, because of the 
complexity of this proposed rulemaking, some commenters may want to 
request additional time for comment submittal. In anticipation of these 
requests, EPA will be communicating with the litigants and the court 
regarding the implications on our rulemaking schedule of a possible 
extension of the comment period for this proposal. If the comment 
period is extended, the Agency will provide notice of such in the 
Federal Register.
    Any person may request a public hearing on this amendment by filing 
a request with Mr. David Bussard, whose address appears below, by 
January 5, 1996.

ADDRESSES: The public must send an original, two copies, and whenever 
possible, a 3.5 inch computer disk containing the comments in a common 
word processing format such as WordPerfect version 5.1 1. to: EPA 
RCRA Docket (5305W), 401 M Street, SW., Washington, DC 20460.

    \1\ This will greatly facilitate EPA's preparation of the 
comment responses and will significantly reduce the cost associated 
with responding to the comments.
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    Place ``Docket number F-95-WHWP-FFFFF'' on your comments. The RCRA 
docket is located at: EPA's Crystal Gateway Office, 1235 Jefferson 
Davis Highway, Arlington, Virginia, and is open from 9 a.m. to 4 p.m., 
Monday through Friday, excluding Federal holidays. The public must make 
an appointment to review docket materials by calling (703) 603-9230. 
The public may copy material from any regulatory docket at a cost of 
$0.15 per page. Copies of the background documents, Integrated Risk 
Information System (IRIS) chemical files, and other references (which 
are not readily available) are available for viewing and copying only 
in the RCRA docket.
    Requests for a public hearing should be addressed to Mr. David 
Bussard, Director, Characterization and Assessment Division, Office of 
Solid Waste (OS-330), U.S. Environmental Protection Agency, 401 M 
Street, SW., Washington, DC 20460.

FOR FURTHER INFORMATION CONTACT: The RCRA/Superfund Hotline at (800) 
424-9346 or at (703) 412-9810. For technical information contact Mr. 
William A. Collins, Jr., Mr. Greg Helms, or Ms. Pamela McMains, Office 
of Solid Waste (5304), U.S. Environmental Protection Agency, 401 M 
Street, S.W., Washington, DC 20460, (202) 260-4770.

Preamble Outline

I. Authority
II. Background
    A. Overview of Hazardous Waste Identification Program
    B. The Mixture and Derived-From Rules and the Contained-In 
Policy
    C. Overview of Expected Impacts of the Exit Rule
III. Scope of Revisions to the Mixture and Derived-From Rules
    A. Rationale for Retention of the Mixture and Derived-From Rules
    B. Revision to Derived-from Rule for Wastes Listed Because They 
Exhibit the Characteristics of Ignitability, Corrosivity, or 
Reactivity
IV. Development of Exit Levels and Minimize Threat Levels
    A. Need for an Exit
    B. Overview of the Exit
    C. Selection of Constituents of Concern
    1. Development of the Master List
    2. Development of the Exit Constituent List
    3. Constituents of Ecological Concern
    D. Risk-Based Information
    1. Human Health Benchmarks
    a. Non-carcinogens
    b. Carcinogens
    c. Consideration of MCLs
    2. Ecological Benchmarks
    3. Sources of Data
    a. Human
    b. Ecological
    E. Risk Assessment
    1. The Risk Analysis
    a. Introduction
    b. How the Analysis was Structured
    c. How Uncertainty is Addressed
    d. Linkage of the Risk Analysis to the Groundwater Fate and 
Transport
    e. Risk Targets Used
    2. Detailed Overview of the Non-Groundwater Risk Analysis
    a. Waste Management Units
    1. Use of Subtitle D Survey
    2. Fate and Transport
    3. Ash Monofill
    i. Particle Size Distribution for Air Dispersion Modeling
    ii. Monofill Characterization
    iii. Vehicle Traffic
    iv. Emission Equations for Ash Blown from Trucks and Spreading 
and Compacting
    4. Land Application Unit
    i. Particle Size Distribution for Air Dispersion Modeling
    ii. Area of Land Application Unit Relative to Agricultural Field
    iii. Application Rate
    iv. Waste Characteristics 
    
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    v. Depth of Contamination
    vi. Partitioning
    5. Waste Pile
    i. Waste Pile Height
    ii. Particle Size Distribution for Air Dispersion Modeling
    iii. Waste Characteristics
    iv. Vehicle Traffic
    v. Emission Equation for Ash Blown from Trucks
    6. Surface Impoundments
    i. Two-Phase Sludge Formation Model
    ii. Dilution of Waste During a Spill
    7. Tank
    i. Unit Characterization
    ii. Volatilization
    8. Combustors
    b. Fate and Transport
    1. Pathways
    2. Equations
    3. Specific Issues on Pathways and Equations
    i. Chemical Transformation
    ii. Biodegradation
    iii. Meteorological Data
    iv. Soil Data
    v. Soil Pathways
    vi. Surface Water Pathways
    vii. Food-Chain Pathways
    c. Receptors
    1. Human Receptors
    2. Ecological Receptors
    3. Groundwater Fate and Transport Modeling
    a. Fate and Transport Processes
    1. Effects of groundwater mounding
    2. Transformation products
    3. Fate and transport of metals
    b. Enhanced solution algorithms
    1. Linkage between unsaturated zone and saturated zone modules
    2. Numerical transport solution
    3. Solution for metals transport
    4. Elimination of biases in determination of receptor well 
concentrations
    c. Revision of Monte Carlo methodology for nationwide 
assessments
    1. Data sources
    2. Finite-source methodology
    3. Site-based regional analysis
    d. Implementation of EPACMTP
    e. Waste management scenarios
    1. Landfills
    2. Surface impoundments
    3. Waste piles
    4. Land application units
    f. Determination of regulatory limits
    g. Chemical specific fate and transport processes
    1. Organic constituents
    2. Metals
    4. Other Risk Assessment Issues
    a. Difference between groundwater and nongroundwater pathways
    1. Infiltration
    2. Density of waste applied to land application unit
    3. Unsaturated zone characteristics
    4. Hydrolysis rates
    b. Other groundwater pathway analysis issues
    1. Use of 1000 years versus 10,000 years exposure time horizon
    2. Implementation of parameter bounds in Monte Carlo procedure
    3. Hydraulic conductivity of surface impoundment bottom layer
    4. Waste pile infiltration rates
    5. Land application unit infiltration rates
    6. Aggregate effects of alternative groundwater modeling 
procedures
    F. Additional Eco-Receptor Consideration
    G. Background Concentrations in Soils and other Issues Relating 
to Results
    H. Constituents with Extrapolated Risk-based Levels
    I. Analytical Considerations
    1. Development of Exemption Quantitation Criteria (EQC)
    2. EQCs and LDR Requirements as Exemption Criteria
    a. EQCs as exit levels
    b. LDR Requirements in combination with EQC Exit Levels
    3. Exemption for Constituents Without EQCs
V. Presentation of Exit Levels
    A. Constituents with Modeled or Extrapolated Risk-based Exit 
Levels
    B. Constituents with Quantitation-based Exit Levels
    C. How to Read the Exit Level Tables
VI. Minimize Threat Levels
    A. Background
    1. Summary of the Hazardous and Solid Waste Amendments of 1984
    2. EPA's Interpretation of Standard for Treatment Requirements
    B. Risk Assessment and Minimize Threat Levels
    1. Rationale
    2. Public Policy Considerations
    C. Minimize threat levels
    1. List of Constituents and Minimize Threat Concentrations
    2. Constituents for which Exit Levels are not Minimize Threat 
Levels
    D. Meeting LDR requirements
    1. Wastes Below Exit Levels as Generated
    2. Wastes Above Exit Levels as Generated
VII. Dilution
VIII. Implementation of Exit
    A. Implementation Requirements
    1. Testing Requirements
    a. Data Evaluation
    i. Compliance with the Exit Levels
    ii. Wastewater and Nonwastewater Categories
    iii. Totals and TCLP Analyses
    iv. Oily Wastes
    b. Initial Test
    2. Notification Requirements
    B. Implementation Conditions
    1. Records Maintained on Site
    2. Testing Conditions
    3. Testing Frequency and Process Change
    C. Public Participation
IX. Request for Comment on Options for Conditional Exemptions
    A. Legal Basis for Conditional Exemptions
    B. Improvements in Management of Non-Hazardous Waste and in Risk 
Assessment Methodology
    C. Overview of Options for Conditional Exemptions
    1. National Approach
    a. Eliminate Disposal in Land Application Units
    b. Unit-Specific Exit Levels for Each Disposal
    c. Consideration of Additional Management Unit Design or 
Management Practices
    2. State Program Approach
    3. Establish Exit Levels that Consider Regional or Site-Specific 
Factors that might Affect Constituent Fate and Transport
    4. Relief from Land Disposal Restrictions
    D. Land Disposal Restrictions for Contingent Management Options
    E. Contingent Management of Mixed Waste
X. Implementation of Conditional Exemption Option 1
    A. Introduction and Overview
    B. When Contingent Management Exemptions Become Effective
    1. Placement of the waste in a qualifying unit
    2. Point of generation
    C. Requirements for Obtaining an Exemption
    1. Sampling and Testing Requirements for Contingent Management 
Exemptions
    2. Requirements for Public Participation in contingent 
Management Exemptions
    3. Notification Requirements for Contingent Management
    D. Implementation Conditions
    1. Tracking conditions
    2. Qualifying Unit
    3. Claimant's Duty to Ensure Compliance with all Conditions
    E. Retesting and Recordkeeping Conditions for Contingent 
Management Exemptions
    F. Compliance Monitoring and Enforcement for Contingent 
Management Exemptions
    1. Compliance Monitoring
    2. Enforcement
    G. Exports of Wastes Eligible for Contingent Management 
Exemptions
     H. Land Disposal Restrictions
XI. Relationship to Other RCRA Regulatory Programs
    A. Hazardous Waste Determination
    B. Characteristic Hazardous Waste
    C. Toxicity Characteristic Level for Lead
    D. Hazardous Waste Listings
    E. Delisting
    F. Requirements for Treatment, Storage, and Disposal Facilities 
and Interim Status Facilities
    G. Closure
    H. HWIR-Media Rule/Subtitle C Corrective Action
    I. Land Disposal Restriction Program
    J. RCRA Air Emission Standards
    K. Hazardous Debris
    L. Hazardous Wastes Used in a Manner Constituting Disposal
XII. CERCLA Impact
XIII. State Authority
    A. Applicability of Rules in Authorized States
    B. Effect of State Authorizations
    C. Streamlining Issues
XIV. Regulatory Requirements
XV. References
Appendix A: Background Tables for Risk Analysis Receptors and 
Pathways
Appendix B: Table Comparing Groundwater Modeling Effects of 1000 vs. 
10,000 years
Appendix C: Tables Comparing the Modeled or Extrapolated Risk Levels 
vs. the EQCs for Each Constituent
Appendix D: Tables Comparing the Exit Levels and the UTS Levels
Regulatory Language

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I. Authority

    These regulations are proposed under the authority of sections 
2002(a), 3001, 3002, 3004 and 3006 of the Solid Waste Disposal Act of 
1970, as amended by the Resource Conservation and Recovery Act of 1976 
(RCRA), as amended by the Hazardous and Solid Waste Amendments of 1984 
(HSWA), 42 U.S.C. 6912(a), 6921, 6922, 6924 and 6926.

II. Background

A. Overview of the Hazardous Waste Identification Program

    Section 1004(5) of the Resource Conservation and Recovery Act 
(RCRA) as amended by the Hazardous and Solid Waste Amendments (HSWA) of 
1984, defines ``hazardous waste'' as ``a solid waste, or combination of 
solid waste, which because of its quantity, concentration, or physical, 
chemical, or infectious characteristics may (A) cause, or significantly 
contribute to an increase in the mortality or an increase in serious 
irreversible, or incapacitating reversible, illness; or (B) pose a 
substantial present or potential hazard to human health or the 
environment when improperly treated, stored, transported, or disposed 
of, or otherwise managed.''
    Section 3001 of RCRA requires EPA to identify those wastes that 
should be classified as ``hazardous.'' The Agency's hazardous waste 
identification rules designate wastes as hazardous in one of two ways. 
First, the Agency has established four hazardous waste characteristics 
which identify properties or attributes of wastes which would pose a 
potential hazard if the waste is improperly managed. See 40 CFR 261.21-
261.24. Any generator of a solid waste is responsible for determining 
whether a solid waste exhibits any of these characteristics. See 40 CFR 
262.11. Any solid waste that exhibits any of the characteristics 
remains hazardous until it no longer exhibits the characteristics. See 
40 CFR 261.4(d)(1).
    The other mechanism EPA uses to designate wastes as hazardous is 
``listing.'' The Agency has reviewed data on specific waste streams 
generated from a number of industrial processes and has determined that 
these wastes would pose hazards if mismanaged for one or more reasons, 
including the presence of significant levels of hazardous constituents 
listed in appendix VIII to 40 CFR part 261, the manifestation of one or 
more of the hazardous waste characteristics, or the potential to impose 
detrimental effects on the environment. (See generally 40 CFR 261.11). 
As discussed in detail in the preambles and in associated dockets 
accompanying the listings, EPA has generally determined that these 
wastes contain toxic constituents at concentrations which pose risks 
which are unacceptable for human or environmental exposure and that 
these constituents are mobile and persistent to the degree that they 
can reach environmental or human receptors.
    On May 19, 1980, as part of the final and interim final regulations 
implementing section 3001 of RCRA, EPA published two lists of hazardous 
wastes: One composed of wastes generated from non-specific sources 
(e.g., spent solvents) and one composed of wastes generated from 
specific sources (e.g., distillation bottoms from the production of 
benzyl chloride). The Agency also published two lists of discarded 
commercial chemical products, off-specification species, container 
residues, and spill residues thereof which are hazardous wastes under 
specific circumstances. These four lists have been amended several 
times, and are currently published in 40 CFR 261.31, 261.32, 261.33(e) 
and (f), respectively.

B. The Mixture and Derived-From Rules and the Contained-In Policy

1. Mixture and Derived-From Rules
a. Scope and Purpose of the Rules
    In 1980 EPA promulgated its first comprehensive regulatory program 
for the management of hazardous waste under RCRA. 45 FR 33066 (May 19, 
1980). As part of that rulemaking EPA promulgated several rules to 
identify hazardous wastes. Two of these rules clarify the scope of the 
hazardous waste listings. Under the mixture rule, a solid waste is a 
hazardous waste if it is mixed with one or more listed hazardous 
wastes. 40 CFR 261.3(a)(2)(iv). Under the derived-from rule a solid 
waste generated from the treatment, storage or disposal of a listed 
hazardous waste is also a hazardous waste. 40 CFR 261.3(c)(2)(i).
    EPA promulgated the mixture and derived-from rules to close 
potentially major loopholes in the subtitle C management system. 
Without a ``mixture'' rule, generators of hazardous wastes could 
potentially evade regulatory requirements by mixing listed hazardous 
wastes with other hazardous wastes or non-hazardous solid wastes to 
create a ``new'' waste that arguably no longer met the listing 
description, but continued to pose a serious hazard. Such a waste also 
might not exhibit any of the hazardous waste characteristics. 
Similarly, without a ``derived-from'' rule, hazardous waste generators 
and owners and operators of hazardous waste treatment, storage, and 
disposal facilities (TSDFs) could potentially evade regulation by 
minimally processing or managing a hazardous waste and claiming that 
resulting residue was no longer the listed waste, despite the continued 
hazards that could be posed by the residue even though it does not 
exhibit a characteristic. (See 57 FR 7628).
    It is for these reasons that the Agency continues to believe that 
the mixture and derived-from rules are extremely important in 
regulating hazardous wastes and reducing risk to human health and the 
environment. However, EPA acknowledges that the mixture and derived-
from rules apply regardless of the concentrations and mobilities of 
hazardous constituents in the waste. The purpose of this rulemaking is 
to reduce any overregulation of low-risk wastes captured by the mixture 
and derived-from rule.
b. Subsequent History
    Numerous industries that generate hazardous wastes challenged the 
1980 mixture and derived-from rules in Shell Oil v. EPA, 950 F. 2d 741 
(D.C. Cir. 1991). In December 1991 the D.C. circuit vacated the rules 
because they had been promulgated without adequate notice and 
opportunity to comment. The court, however, suggested that EPA might 
want to consider reinstating the rules pending full notice and comment 
in order to ensure continued protection of human health and the 
environment.
    In response to this decision, EPA promulgated an emergency rule 
reinstating the mixture and derived-from rules as interim final rules 
without providing notice and opportunity to comment. 57 FR 7628 (Mar.3, 
1992). EPA also promulgated a ``sunset provision'' which provided that 
the mixture and derived-from rules would remain in effect only until 
April 28, 1993. Shortly after, EPA published the proposal containing 
several options for revising the mixture and derived-from rules. See 57 
FR 21450 (May 20, 1992). This proposal also included options for 
exempting media contaminated with listed hazardous wastes that are 
regulated under the ``contained in'' policy.
    The May 1992 proposal and the time pressure created by the ``sunset 
provision'' generated significant controversy. In response, Congress 
included in EPA's 1992 appropriations bill several provisions 
addressing the mixture and derived-from rules. Pub. L. No. 102-389, 106 
Stat. 1571. First, Congress nullified the sunset provision by providing 
that EPA could not promulgate any revisions to the rules 

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before October 1, 1993 and by providing that the reinstated regulations 
could not be ``terminated or withdrawn'' until revisions took effect. 
However, to ensure that EPA could not postpone the issue of revisions 
indefinitely, Congress also established a deadline of October 1, 1994 
for the promulgation of revisions to the mixture and derived-from 
rules. Congress made this deadline enforceable under RCRA's citizen 
suit provision.
    On October 30, 1992 EPA published two notices, one removing the 
sunset provision, and the other withdrawing the May 1992 proposal. See 
57 FR 49278, 49280. EPA had received many comments criticizing the May 
1992 proposal. The criticisms were due, in a large part, to the very 
short schedule imposed on the regulation development process itself. 
Commenters also feared that the proposal would result in a 
``patchwork'' of differing State programs because some states might not 
adopt the revisions. This fear was based on the belief that States 
would react in a negative manner to the proposal and refuse to 
incorporate it into their programs. Finally, many commenters also 
argued that the risk assessment used to support the proposed exemption 
levels failed to provide adequate protection of human health and the 
environment because it evaluated only the risks of human consumption of 
contaminated groundwater ignoring other pathways that could pose 
greater risks. Based on these concerns, and based on the Agency's 
desire to work through the individual elements of the proposal more 
carefully, the proposal was withdrawn.
    Meanwhile, a group of waste generating industries challenged the 
March 1992 action that reinstated the mixture and derived-from rules 
without change. Mobil Oil Corp. v. EPA, 35 F.3d 579 (D.C. Cir. 1994). 
EPA argued that the 1992 appropriations act made the challenge moot 
because it prevented both EPA and the courts from terminating or 
withdrawing the interim rules before EPA revised them, even if EPA 
failed to meet the statutory deadline for the revisions. In September, 
1994 the D.C. Circuit issued an opinion that dismissed the challenges 
as moot under the rationale that the Agency had offered.
    In early October 1994 several groups of waste generating and waste 
managing industries filed citizen suits to enforce the October 1 
deadline for revising the mixture and derived-from rules. The U.S. 
District Court for the District of Columbia Circuit entered a consent 
decree resolving the consolidated cases on May 3, 1993. Environmental 
Technology Council v. Browner, C.A. No. 94-2119 (TFH) (D.D.C. 1994) 
Under this decree the Administrator must sign a proposal to amend the 
mixture and derived-from rules by November 13, 1995 and a notice of 
final rulemaking by December 15, 1996. The decree also specifies that 
the deadlines in the 1992 appropriations act do not apply to any rule 
revising the separate regulations that establish jurisdiction over 
media contaminated with hazardous wastes.
c. Federal Advisory Committees Act (FACA) and Outreach
    After the withdrawal of the HWIR proposal, the Agency initiated a 
series of public meetings with invited representatives from industry, 
environmental groups, hazardous waste treaters, and States. These 
meetings focused on three major issues: --RCRA regulation of low hazard 
wastes with a particular interest in addressing issues raised regarding 
the mixture and derived-from rules; concerns that full RCRA 
requirements for contaminated media may unnecessarily impede clean-ups; 
and need to regulate additional high-risk wastes outside the scope of 
the current listings and characteristics.
    A strong and successful effort was made to encourage all the 
interested parties to participate in the public meetings. EPA forged a 
solid partnership with the States (both ASTSWMO and Environmental 
Commissioners under the National Governors Association) and the state 
representatives worked closely with EPA as co-regulators in our 
analyses of options.
    In July of 1993, EPA chartered this group as an advisory committee 
under the Federal Advisory Committee Act (Pub. L. 92-463)(58 FR 36200).
    The committee rather quickly formed two sub-committees to allow 
separate discussion of the low risk waste problem associated with the 
mixture and derived-from rules and the rules for managing contaminated 
media and other wastes during remediation.
    By September of 1994 the low risk waste group had made significant 
progress in identifying options for creating exemptions for low risk 
wastes. Despite significant investment of time and effort, however, the 
group was unable to reach consensus on many key issues.
    With the statutory deadline for revisions to the mixture and 
derived-from rules approaching, EPA requested that group to present a 
final report in late September of 1994. EPA and representatives from 
several state environmental agencies then took up the task of selecting 
options for creating an exit rule, crafting regulatory language, and 
developing necessary supporting materials. The FACA subcommittee's 
final report was taken into consideration during the development of 
today's proposal.
2. Contained-In Policy
    The Agency also has interpreted its regulatory definition of 
hazardous waste to extend to mixtures of hazardous wastes and 
environmental media (such as contaminated soil and groundwater).2 
See 40 CFR 261.3(c)(1) and (d)(2). Media that are contaminated with 
listed or characteristically hazardous waste must be managed as 
hazardous wastes until they no longer contain such wastes. To date, the 
Agency has not issued any general rules as to when, or at what levels, 
environmental media contaminated with hazardous wastes are no longer 
considered to ``contain'' those hazardous wastes. Media that contain 
hazardous wastes with constituent concentrations below the levels 
proposed today will be eligible for exemption under the procedures 
proposed today. In addition, in a separate rulemaking, the Agency plans 
to propose additional rules reducing regulation of contaminated media 
during remediation activities.

    \2\ EPA's ``contained in'' policy was upheld as a reasonable 
interpretation of 40 CFR 261.3(c)(1) and (d)(2) by the D.C. Circuit 
in Chemical Waste Management, Inc v. U.S. EPA, No. 869 F.2d 1526 
(D.C. Cir. 1989).
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C. Overview of Expected Impacts of the Exit Rule
1. Listed Wastes
    The purpose of this rule is to exempt from hazardous waste 
regulation those solid wastes currently designated as hazardous waste 
even though they contain constituent concentrations at levels that pose 
very low risk to human health and the environment. While facilities 
generating such wastes can petition for delisting by rulemaking under 
the provisions of 40 CFR Sec. 260.20 and 260.22, EPA believes that the 
detailed waste-stream specific review required under delisting is not 
necessary for the low risk wastes that are identified by today's 
proposal. The alternative, generic exit rule proposed today will be 
faster and less resource-intensive for both the Agency and the 
regulated community. By providing an opportunity for a more self-
implementing exemption, the Agency intends to create incentives for 
effective and innovative waste minimization and waste treatment and to 
reduce unnecessary demand for Subtitle C disposal capacity, without 

[[Page 66348]]
compromising needed environmental protection.3

    \3\ As will be discussed further in this notice, the Agency 
believes that the delisting process will continue to be valuable for 
certain types of wastes which are not eligible for an exemption 
under this proposal. Thus the Agency is not proposing to eliminate 
or modify the delisting program as a result of this proposal.
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    By proposing a risk-based ``floor'' to listed wastes, today's 
proposal should give a very strong incentive to generators of listed 
hazardous waste to apply pollution prevention to their processes to 
avoid Subtitle C control. This action should also give incentive for 
the development of innovative treatment technologies to render wastes 
less risky.
    Today's proposed rule specifies sampling and analysis requirements, 
public participation, reporting and record keeping requirements. Most 
of these provisions are alternatives to the safeguard of waste-specific 
review provided under the delisting program. The exit levels are risk-
based concentrations at which a human or wildlife species could be 
directly or indirectly exposed to the exempted waste, and would be 
unlikely to suffer adverse health effects. The exposure scenario used 
to develop these levels assume that the exempted waste will no longer 
be subject to Subtitle C control, but will be managed as a solid waste 
in one of a variety of non-hazardous waste management units regulated 
under Subtitle D.
2. Characteristic Wastes
    Listed hazardous wastes exempted under today's proposed rule which 
exhibit any of the characteristics will continue to be regulated as 
hazardous wastes until the characteristic is removed. In a number of 
cases, wastes were listed on the basis of containing both toxic 
hazardous constituents and exhibiting one or more of the hazardous 
waste characteristics that do not relate to chemical toxicity (e.g., 
ignitability, corrosivity, or reactivity). If such a waste still 
exhibits any characteristic after complying with the exemption criteria 
proposed in today's proposed rule, it must continue to be managed as a 
characteristically hazardous waste.

III. Scope of Revisions to the Mixture and Derived-From Rules

    The mixture and derived-from rules promulgated in 1980 and 
reinstated in 1992 require Subtitle C regulation of all mixtures of 
listed hazardous wastes and solid wastes and all residuals from 
treatment of hazardous wastes. The rules proposed today, however, allow 
rapid exemptions for mixtures and derived-from wastes that present no 
significant threats to human health and the environment. Those wastes 
that would remain subject to the mixture and derived-from rules 
typically will pose risks that warrant regulation under Subtitle C. To 
the extent that this is not true for a particular mixture or treatment 
residual, the delisting process remains available (at least at the 
state level) to exempt wastes with constituents at more site- and 
waste-specific levels. Consequently, EPA has tentatively determined 
that further revisions of the mixture and derived-from rules, with the 
exception of the one minor change to the derived-from rule discussed 
later in this section, are not warranted in this rulemaking. However, 
EPA requests comment on this conclusion.

A. Rationale for Retention of the Mixture and Derived-From Rules

    EPA continues to believe that it had ample statutory and regulatory 
authority to promulgate the original rules and that it also has ample 
authority to maintain the rules without further revisions. The mixture 
and derived-from rules, particularly with the revisions proposed today, 
ensure that hazardous wastes that are mixed with other wastes or 
treated in some fashion do not escape regulation so long as they are 
reasonably likely to continue to pose threats to human health and the 
environment. They thus retain jurisdiction over listed hazardous wastes 
and clarify that such wastes are not automatically eligible for exit 
when they are mixed or treated. Although RCRA sets out criteria for the 
identification of hazardous wastes to enter the subtitle C system, it 
is silent on the question of how to determine that a waste is eligible 
to exit the system. EPA's interpretation of the statute is thus 
entitled to deference so long as it is reasonable and consistent with 
RCRA's purposes.
    EPA believes that its decision to retain jurisdiction over major 
portions of the universe of waste mixtures and treatment residues is 
consistent with its authorities under sections 3002-3004 of RCRA to 
impose requirements on waste handlers until wastes have ``cease[d] to 
pose a hazard to the public''. Shell Oil Corp. v. EPA, 959 F.2d 741, 
754 (D.C. Cir. 1991). See also Chemical Manufacturers Assoc. v. EPA, 
919 F.2d 158, 162-65 (EPA may regulate the disposal of nonhazardous 
wastes in a hazardous waste impoundment under section 3004) and 
Chemical Waste Management, Inc. v. EPA, 976 F.2d 2, 8, 13-14 (D.C. Cir. 
1992) (EPA may require further treatment of wastes under section 3004 
even though they cease to exhibit a hazardous characteristic).
    The mixture and derived-from rules are also valid exercises of 
EPA's authority to list hazardous wastes under section 3001. That 
provision gives EPA broad authority to promulgate listing criteria. 
EPA's 1980 criteria authorize the listing of classes of hazardous 
wastes when it has reason to believe that wastes in the class are 
typically or frequently hazardous. See 40 CFR 261.11(b). Such class 
listings are permissible even if some members of the class do not 
actually pose hazards. Nothing in the section 1004(5) definition of 
hazardous waste, in section 3001, or in EPA's listing criteria require 
EPA to prove that every member of a class poses a hazard. In fact, many 
waste listings describe ``classes'' of hazardous wastes because they 
cover a range of materials that are not identical in composition. The 
mixture and derived-from rules thus are fully authorized as class 
``listings'' under section 3001.
    EPA has also made a reasonable factual determination that these 
classes of waste warrant regulation under sections 3002-3004 and 
section 3001. In 1980 EPA determined that the hazardous constituents 
contained in these wastes are not generally eliminated or rendered 
nontoxic simply because a waste is mixed with other wastes or managed 
in some fashion. In 1992, when EPA repromulgated the mixture and 
derived-from rules, it documented numerous instances of mixed and 
derived-from wastes that continued to pose hazards. See 57 FR 7629 
(March 3, 1992). Today, EPA is proposing that members of this class of 
wastes that pose low risks will be eligible for an expedited, self-
implementing exemption from Subtitle C regulation. Accordingly, EPA has 
an even better basis for believing that wastes which remain within the 
scope of the mixture and derived-from rules pose threats warranting 
regulation.
    Additionally, EPA continues to believe, as it did in 1980, that it 
would be virtually impossible to try to identify all possible waste 
mixtures and treated wastes and assess their hazards individually. 
EPA's rule reasonably retains jurisdiction over both broad classes and 
places the burden of proof on the regulated community to show that a 
particular waste has ceased to present a hazard. Today's self-
implementing exit proposal will reduce that burden significantly, 
ensuring that the mixture and derived-from rules represent a reasonable 
approach to regulating these classes of wastes.

[[Page 66349]]


B. Revision to Derived-from Rule for Wastes Listed Because They Exhibit 
the Characteristics of Ignitability, Corrosivity, or Reactivity

    In 1981 EPA responded to a number of comments on the scope of the 
original 1980 mixture rule by promulgating a number of exemptions for 
mixtures of solid wastes and listed hazardous wastes which, according 
to information submitted by commenters, posed no significant risk to 
human health and the environment. See 46 FR 56582 (Nov. 17, 1981). The 
1981 rule included an exemption for mixtures of solid wastes and 
hazardous wastes listed solely because they exhibited one or more of 
the hazardous waste characteristics, if the resultant mixtures no 
longer exhibited a characteristic. The exemption was based on a finding 
that such mixtures did not pose threats to human health and the 
environment warranting Subtitle C regulation. See 46 FR 56568 and the 
current text of the exemption at Sec. 261.3(a)(2)(iii). EPA notes that 
it has never promulgated any listings for wastes solely on the basis 
that they exhibit either the 1980 EP toxicity characteristic or the 
1990 toxicity characteristic; consequently, only mixtures containing 
wastes listed because they exhibit the characteristics of ignitability, 
corrosivity, or reactivity have been eligible to exit Subtitle C when 
they no longer exhibit the characteristic.
    The 1981 notice focused exclusively on issues concerning the 
mixture rule. Consequently, EPA did not propose any parallel exemption 
for such wastes for the separate derived-from rule (codified at 
Sec. 261.3(c)(2)(i)), even though the derived-from wastes would appear 
to present similarly low risks if they no longer exhibited a 
characteristic and were treated to meet LDR standards before land 
disposal. Recent inquiries from the public have highlighted the 
discrepancy in the scope of the mixture rule and the derived-from rule 
for wastes listed solely because they exhibit characteristics. EPA 
believes it has no reason to treat derivatives of wastes listed solely 
because they exhibit the characteristic of ignitability, corrosivity, 
or reactivity any differently from the way it treats mixtures of such 
wastes because both present similar low risks to human health and the 
environment.
    Consequently, EPA is today proposing a revision to the derived-from 
rule that will closely resemble the 1981 revision to the mixture rule. 
Since no listings to date have been based on the toxicity 
characteristic, EPA is proposing to limit the new revision to the 
derived-from rule to wastes listed because they exhibit only the 
characteristics of ignitability, corrosivity, or reactivity. EPA is 
also not proposing to exempt wastes that might in the future be listed 
only because of the toxicity characteristic because (as this rule 
proposal indicates) there can be risk concerns with the TC constituents 
below TC levels. EPA requests comment on this proposal to create a new 
exemption to the derived-from rule for this limited category of listed 
wastes.
    The proposed exemption will also remind the regulated community of 
the separate duty to comply with requirements imposed by the part 268 
regulations implementing the LDR program. In CWM v. EPA, 976 F.2d 2 
(D.C. Cir. 1992), the U.S Court of Appeals for the D.C. Circuit 
interpreted RCRA section 3004(m) as requiring treatment of de-
characterized hazardous wastes to meet LDR treatment standards even 
after the wastes cease exhibiting a characteristic. EPA believes that 
de-characterized derived-from residues from wastes listed because they 
exhibit characteristics also must meet LDR requirements, unless they 
are either delisted or are exempt at the point of generation pursuant 
to other provisions proposed in this rule (e.g., meeting HWIR levels at 
the point of generation).
    In 1992 EPA amended the 1981 exemption to mixture rule to provide a 
similar cross-reference and clarification for mixtures containing de-
characterized listed wastes. See 57 FR 37194, 37210-11 (Aug. 18, 1992). 
That 1992 clarification, however, only covers nonwastewater mixtures. 
As explained in that mixture rule preamble, EPA then regulated de-
characterized wastewaters much less stringently under the LDR program. 
Consequently, EPA did not believe it was necessary to remind the 
regulated community to comply with LDR requirements for wastewater 
mixtures.
    Later in 1992 the CWM v. EPA decision invalidated most of the 
distinctions between the LDR rules for wastewaters and nonwastewaters. 
EPA is now revising the LDR program to comply with that decision in the 
LDR Phase III and Phase IV rulemakings. To reflect the changes in LDR 
regulation of wastewaters, the derived-from rule exemption proposed 
today reminds the regulated community of the need to comply with part 
268 LDR requirements for all types of derived-from residues. EPA 
requests comment on this clarifying language. EPA also requests comment 
on whether it should revise the LDR clarification for the mixture rule 
as well.

IV. Development of Exit Levels and ``Minimize Threat'' Levels

A. Need for the Exit

    The primary purpose of this rule is to address listed hazardous 
wastes, mixtures of listed hazardous wastes and solid wastes, and 
residues derived-from managing listed hazardous waste that, under 
current rules, continue to be designated as ``hazardous waste'' 
although they are either generated with constituent concentrations that 
pose low risks or treated in a manner that reduces constituent 
concentrations to low levels of risk.
    EPA notes that there are currently exemptions, both codified and 
contained in policy directives, from the hazardous waste identification 
system, particularly the mixture and derived-from rules, for certain 
types of wastes or wastes with certain constituent concentrations. See 
e.g. 40 CFR 261.3(a)(2)(iv)(A) through (E) and policy memorandums such 
as the ``Skinner Memorandum'' dated August 23, 1995. EPA is not 
proposing to modify or replace any of these exemptions and policy 
statements.

B. Overview of the Exit

    For 191 of the 376 constituents of concern, EPA conducted a 
detailed human health risk analysis to develop risk-based levels for 
either the wastewater or nonwastewater form of a constituent (or both). 
To conduct this analysis, EPA identified five types of units actually 
and rather frequently used to manage nonhazardous wastes that covered 
the full range of environmental releases needing analysis. The May 1992 
proposal of exit levels for listed wastes, like many previous RCRA 
rules, assessed only risks from releases to groundwater. In response to 
complaints that such an assessment would not protect human health and 
the environment from other types of releases, EPA also assessed 
potential releases to air, surface water and soil in this proposal.
    For each category of releases, EPA evaluated both relatively simple 
pathways (such direct human ingestion of contaminated groundwater) and 
more complex pathways (such as the deposition of windblown waste 
particles on agricultural land, followed by crop uptake, consumption of 
the crop by cattle, and consumption of contaminated beef or milk by 
humans). EPA assessed approximately 8 to 27 release pathways depending 
on the type of waste management unit.
    Additionally, EPA screened the same group of 191 constituents to 
identify the highest priorities for assessment of 

[[Page 66350]]
ecological receptors. In addition, EPA considered for its assessment 
the toxicological effects of silver on ecological receptors. EPA 
conducted a specific assessment of ecological risks for 47 constituents 
using the same five units and the same pathways (modified to reflect 
ecological exposures) for each unit. This risk assessment is described 
in more detail in sections V.B. and C.
    Data limitations and resource constraints prevented EPA from 
conducting a risk analysis for the remaining constituents of concern. 
For each of these constituents, EPA extrapolated exit levels from 
levels derived-from the risk assessment for similar chemicals. EPA's 
extrapolation methodology is described in section IV.F.
    The current capabilities of analytical chemistry constrain EPA's 
ability to use some of concentrations as exit levels. For approximately 
one-fourth of the constituents, EPA found that available methods could 
not routinely measure the constituent at the modeled or extrapolated 
risk-based exit level.

C. Selection of Constituents of Concern

1. Development of the Master List
    EPA developed an initial ``Master List'' of 506 constituents to be 
evaluated for purposes of establishing exit criteria. This master list 
was developed by combining the constituents specifically listed in the 
following appendices of 40 CFR part 261: Appendix VII, Basis for 
Listing Hazardous Waste; Appendix VIII, Hazardous Constituents; and 
appendix IX of part 264, the Ground-Water Monitoring List. The master 
list includes the full list of constituents referenced in appendix VII, 
including the F039 constituents.
    Appendix VII to part 261, which was originally promulgated on May 
19, 1980 (45 FR 33084) sets out the chemical constituents found to pose 
threats to human health and the environment that served as the actual 
basis for each of EPA's original hazardous waste listings. Appendix 
VIII to Part 261, also promulgated in 1980, is a more general listing 
of chemicals found to pose potential threats to human health and the 
environment. (45 FR 33084). EPA considers wastes containing appendix 
VIII constituents to be candidates for listing determinations. EPA 
amends appendix VII from time to time as EPA identifies additional 
potentially toxic constituents.
    EPA later promulgated appendix IX to part 264 to identify those 
appendix VIII constituents which it could routinely expect owners and 
operators of permitted hazardous waste treatment, storage and disposal 
facilities to monitor in groundwater. EPA also included in this 
appendix 17 additional constituents found to pose significant risks 
that the Superfund program routinely monitored in groundwater. (52 FR 
25942, July 9, 1987).
    EPA established in these rulemakings that each of these 
constituents had significant potential to threaten human health, and, 
by implication, potential to threaten the environment. (Most of the 
data EPA utilized predicted toxic effects on humans.) EPA finds it 
reasonable to include each of these constituents on the list of 
chemicals of concern.
    Further, EPA believes that, with the exception of the six chemicals 
identified below, the three appendices identify the chemicals of 
current concern to EPA that are likely to be found in listed wastes.
    The Agency requests comment on whether the master list should also 
include six constituents that are not listed in any of the above 
sources. These six constituents, which are listed in Table 1, are found 
in six ``U'' listed wastes (commercial chemical products that become 
hazardous wastes when discarded). See 40 CFR 261.33(f). EPA originally 
listed these wastes because they routinely exhibited the characteristic 
of ignitability. Since the original listings, however, sufficient 
toxicity data have become available for these constituents. (The risk 
number for dimethylamine was recently withdrawn; however, EPA 
understands that it will shortly be replaced). Because of the toxicity 
data associated with these constituents, the Agency is taking comment 
on whether exit levels should be established for these six constituents 
in today's rulemaking. The Agency also requests comment on whether 
these six constituents should be added to Appendix VIII.

                            Table 1.--Constituents Not on Appendices VII, VIII, or IX                           
----------------------------------------------------------------------------------------------------------------
                                                                                              Nonwastewater     
                CAS #                              Constituent              Wastewater -------------------------
                                                                                           Totals       Leach   
----------------------------------------------------------------------------------------------------------------
 75-07-0.............................  Acetaldehyde (ethanal)............  ...........  ...........  ...........
 98-82-8.............................  Cumene............................          .67       18,000          2.5
124-40-3.............................  Dimethylamine.....................  ...........  ...........  ...........
110-00-9.............................  Furan.............................          .16         1300          .06
 79-10-7.............................  Acrylic acid......................        (\1\)        (\1\)        (\1\)
 98-01-1.............................  2-Furancarbox- aldehyde (furfural)        (\1\)        (\1\)        (\1\)
----------------------------------------------------------------------------------------------------------------
\1\ No exit levels because no EQC is available for this constituent. The criteria for exit would be to meet LDR 
  treatment standards in Sec.  268.                                                                             

    Full documentation concerning the selection of constituents of 
concern is available in the docket under The Background Document to 
Support Development of the Final Constituent List under the Waste Exit 
Rule.
2. Development of the Exit Constituent List
    The Agency narrowed the list of 506 constituents to consist of 376 
constituents that are included in the exemption list. 130 constituents 
were deleted from the master list. Criteria for constituent deletions 
from the master list include: Reactivity in air, analysis as a 
different constituent, reactivity in water, hydrolysis in soil or 
water, or is part of a chemical class with a specific constituent 
represented on the list. Because different methods and quantitation 
limits are necessary for solid and liquid matrices, two separate 
analyses were conducted. The Background Document to Support Development 
of the Final Constituent List under the Waste Exit Rule in the docket 
further justifies deletions of constituents from the master list and 
lists the deleted constituents.
    Molybdenum is not on the Appendices VII, VIII, or IX, which 
provided the scope of today's master list of constituents. In 
anticipation of the Petroleum listing, due to a Drinking Water Sewage 
Sludge regulatory level, and due to available toxicity information, the 
Agency has included molybdenum on the exemption list. Due to modeling 
time constraints, Molybdenum was not modeled for groundwater risk. The 
groundwater 

[[Page 66351]]
leach level was estimated by assuming a DAF of 10 and using the RfD. 
The Agency requests comment on whether molybdenum should be on the 
list.
    Two modeled constituents do not have estimated quantitation 
criteria (EQCs--see section IV.G.) and therefore do not have associated 
exit levels. These constituents are ethylene thiourea and phenyl 
mercuric acetate. The Agency requests comment on how to deal with these 
two constituents. The following table represents modeled results for 
these constituents for comment.

                                   Table 2.--Modeled Constituents Without EQCs                                  
----------------------------------------------------------------------------------------------------------------
                CASNUM                            Constituent            NWW totals     NWW leach     WW totals 
----------------------------------------------------------------------------------------------------------------
96-45-7...............................  Ethylene thiourea.............     0.51          0.00017         .00053 
62-38-4...............................  Phenyl mercuric acetate.......     0.0093        0.0045         0.012   
----------------------------------------------------------------------------------------------------------------

    EPA modeled chromium VI in the risk assessment. However, totals 
chromium appears on the exit tables based on the exit levels calculated 
from modeling chromium VI. This approach is consistent with the 
Toxicity Characteristic approach to chromium. The Agency asks for 
comment on this approach.
    The cyanide exit level was extrapolated. It is meant to be totals 
cyanide. The Agency requests comment on whether testing for totals 
cyanide is appropriate.
    The values in the exit tables for silver do not represent results 
of human toxicity data for silver, rather they represent ecological 
results from the risk assessment. The Agency has determined that the 
effect of silver on humans is not a human health problem, rather it is 
an aesthetic problem. The groundwater model did not model ecological 
exposure, therefore, there is no groundwater risk level for silver.
3. Constituents of Ecological Concern
    As explained above, EPA established in previous RCRA rulemakings 
that the constituents on the exit list (376) present significant 
threats to human health. Numerous comments submitted on EPA's May 1992 
proposal to establish exit levels urged EPA to conduct a more specific 
and detailed analysis of threats to non-human species. Consequently, in 
this rulemaking EPA determined the constituents it believed to also be 
reasonably likely to pose risks to ecological receptors.
    EPA has not set benchmarks for ecological impacts for a large 
number of constituents under any of its programs. Establishing such 
benchmarks for this proposal would be a resource-intensive and time-
consuming task. Accordingly, EPA narrowed the list of exit constituents 
for which ecological receptors would be evaluated. First, EPA decided 
to consider only the 191 constituents which it had already targeted for 
analysis to protect human health. Second, the Agency developed a 
methodology for screening the 191 constituents to identify those most 
likely to pose significant risks to ecological receptors.
    Based on an extensive review of available literature, EPA developed 
five criteria to indicate the potential for ecological risks:
    (1) Constituents that bioaccumulate (and possibly biomagnify) in 
the food chain that can present elevated exposures to certain 
predators;
    (2) Persistent constituents that are likely to increase long-term 
multi-generational exposures in wildlife;
    (3) Constituents that cause reproductive and developmental effects 
that can elicit adverse effects at sensitive life stages;
    (4) Constituents that may cause ecological effects that have no 
human analog (e.g., eggshell thinning); and
    (5) Constituents that may cause effects to ecological receptors 
continuously exposed.
    EPA also developed operational definitions for each criterion. The 
definitions were quantitative where possible. Further details can be 
found in appendix B of the Technical Support Document for the Risk 
Assessment for Human and Ecological Receptors.
    EPA decided to designate as constituents of ecological concern the 
47 constituents that exhibited at least two of the five criteria. The 
Agency believes these constituents present the highest priorities in 
terms of environmental risk. An additional 36 constituents exhibited 
only one criterion. EPA, however, chose not to designate them as 
constituents of concern because time and resource constraints would 
prevent the Agency from completing an analysis with these constituents. 
EPA, nevertheless, believes it has identified and analyzed sufficient 
constituents of concern to ensure that the exit levels proposed today 
provide for reasonable protection of the environment. Only 83 of 191 
screened constituents showed any significant potential to pose threats 
to the environment at levels protective of human health. Further, as 
discussed in more detail below, of the 47 constituents that EPA 
actually assessed for ecological impacts, only 6 wastewater 
constituents and 18 nonwastewater constituents required exit levels to 
protect environmental receptors lower than those necessary to protect 
human health under the baseline proposal. Consequently, EPA believes it 
is unlikely that all of the remaining constituents will present 
significant threats to ecological receptors at levels that would 
adequately protect human health.

D. Risk-Based Information

    The Agency's proposed option for establishing exit values is based 
on risk modeling to a hazard quotient of 1 and a 1 x 10-6 cancer 
risk. The Agency chose a hazard quotient of 1 as its toxicity benchmark 
value for non-carcinogens because evaluation of these compounds 
presumes there is a threshold exposure above which individuals would be 
at significant risk of suffering the adverse effects attributable to 
the compound. The HQ is the Agency's best attempt to estimate that 
level. Therefore, the Agency believes all exposures should remain below 
HQ 1. Some Agency programs rely on HQ values less than 1 in standard 
setting (the drinking water program uses an HQ of 0.20 to provide a 
safety factor which allows for exposure to the constituent from sources 
other than drinking water).
    The Agency chose a toxicity benchmark of 1  x  10-6 cancer 
risk for carcinogens for several reasons. A cancer risk level of 1  x  
10-5 risk was used as a clearly hazardous level in establishing 
the toxicity characteristic. Second, in the listings program, a 1  x  
10-4 cancer risk is used as the presumptive listing risk, and a 1 
x  10-6 as the presumptive no-list level. A cancer risk of 1  x  
10-5 represents a level of initial concern about risk. Therefore, 
in allowing listed hazardous waste to exit the requirements of Subtitle 
C, the Agency was targeting waste that is clearly not hazardous. Thus, 
the Agency believes the risk level should be at the 

[[Page 66352]]
low end of the risk range used to bring waste into the hazardous waste 
system.
    Similarly, the Agency sought to be protective of public health in 
developing its fate and exposure modeling. For the groundwater 
evaluation, the Agency used a DAF 10 (which represents an approximate 
90th percentile protection level) for infinite source type 
constituents. (Constituent-specific DAFs were developed using the same 
input assumptions, and different DAFs result from modeling of 
degradation or retardation factors in the environment). This is the 
generic DAF used in the delisting program for large volume wastes. 
Since this is a national program which will largely benefit the largest 
volume generators, the DAF 10 assumption is consistent with delisting 
practice. Also, the toxicity characteristic used a DAF of 100 
(representing an approximate 85th percentile protection level) for 
identifying clearly hazardous waste (for infinite source type 
constituents; regulation of hydrolysers was deferred). Again the policy 
goal of exits was to strive to be well below clearly hazardous levels. 
The Agency also modeled exposure at the nearest downgradient well. The 
TC rule restricted well placement to within the plume. Today's proposal 
attempts to balance the protectiveness level and well placement by 
requiring a more protective level than the TC rule, but is less 
restrictive in well location, e.g., wells outside of the plume, at 
significantly lower risk, are averaged in.
    For modeling of the non-groundwater pathways, the Agency used four 
high-end parameter values for which the modeling outcome is most 
sensitive as inputs to the analysis to be protective of public health 
and the environment. These include: Two high-end parameters in the 
waste management unit characterization and fate portions and two high-
end parameters in the exposure portions of the model. The remaining 
input parameters were evaluated at typical values or central tendency 
values. The Agency sought to be protective of a high percentile exposed 
population (at least 90th percentile).
1. Human Health Benchmarks
    For each constituent on the master list, the Agency evaluated the 
existing toxicity information to determine whether there were 
sufficient toxicity data to establish a benchmark. For those 
constituents with adequate data, the data were evaluated either by the 
Agency's CRAVE (Carcinogen Risk Assessment Verification Endeavor) 
Workgroup, Reference Dose/Reference Concentration (RfD/RfC) Workgroup, 
or the Office of Research and Development. This approach is consistent 
with the approach used in the Agency's other risk-based RCRA programs 
such as the Toxicity Characteristic, delisting petition evaluations, 
listings, as well as the CERCLA program. See Section 4, ``Benchmarks,'' 
of the Technical Support Document for the Hazardous Waste 
Identification Rule: Risk Assessment for Human and Ecological Receptors 
for more details.
a. Non-carcinogens
    The Agency proposes to use oral reference doses (RfDs) and 
inhalation reference concentrations (RfCs) as the basis for developing 
the exit criteria for non-carcinogenic constituents. An RfD or RfC is 
an estimate (with uncertainty spanning perhaps an order of magnitude) 
of a daily exposure to a constituent for the human population 
(including sensitive subgroups) that is likely to be without an 
appreciable risk of deleterious effects during a lifetime.
    The approach used to derive an RfD or RfC is to identify the 
highest test dose of a constituent associated with no effects or 
effects that are not considered adverse in an appropriate animal 
bioassay test. These experimental no-observed-adverse-effect-levels 
(NOAELs) or no-observed-effect-levels (NOELs) are considered to be an 
estimate of the animal population's physiological threshold for adverse 
effects. The RfD or RfC is derived by dividing the NOAEL or other 
toxicity benchmark by suitable uncertainty and modifying factors. In 
the event that an appropriate NOAEL or NOEL is not available, the 
lowest-observed-adverse-effect level (LOAEL) may be used with 
additional uncertainty factors.
    It is important to note that the contributions of the constituent 
from various sources in the environment (e.g., air, food, water) are 
not considered in the development of an RfD or RfC. Rather, the RfD or 
RfC reflects the estimated total permissible daily human exposure from 
all sources of exposure. RfDs and RfCs have been calculated for many, 
but not all, of the non-carcinogenic constituents for which the Agency 
is establishing exit criteria.
    The Agency prefers to use only RfDs and RfCs that have been 
evaluated and verified by the RfD/RfC Workgroup as the basis for 
setting regulatory levels. However, for some constituents, the Agency 
has not yet completed its verification process; thus, RfDs and RfCs 
under development are being used for purposes of this proposal for 
those constituents. If the final verified RfDs and RfCs differ from the 
RfDs and RfCs under development proposed in today's notice, the Agency 
will adopt the new (i.e., verified) values for the final rule after 
noticing the data in the Federal Register.
b. Carcinogens
    The Agency proposes to use the oral cancer slope factor and 
inhalation cancer unit risk as the basis for developing exit levels for 
carcinogenic constituents unless the non-carcinogenic effects occur at 
lower levels. EPA's CRAVE Workgroup and Office of Research and 
Development have estimated the carcinogenic slope factor (CSF) (i.e., 
the slope of the ``dose-response'' curve) and inhalation unit risks for 
humans exposed to low-dose levels of carcinogens in the environment. 
The slope factors indicate the upper-bound confidence limit estimate of 
excess cancer risk for individuals experiencing a given exposure over a 
70-year lifetime. In practice, a given dose multiplied by the slope 
factor gives an upper estimate of the lifetime risk to an individual of 
developing cancer. By specifying a level of lifetime risk (no matter 
how small), one can also estimate the corresponding dose using the 
slope factor.
    EPA proposes to quantify on a weight-of-evidence basis, as 
described below. EPA promulgated ``Guidelines for Carcinogen Risk 
Assessment'' on September 24, 1986 (51 FR 33992), which defined a 
scheme to characterize substances based on experimental data and the 
kinds of responses induced by a suspect carcinogen. These guidelines 
specify the following five classifications:

Group A--Human carcinogen (sufficient evidence from epidemiologic 
studies)
Group B--Probable human carcinogen
Group B1--Limited evidence of carcinogenicity in humans
Group B2--A combination of sufficient evidence in animals and 
inadequate or no evidence in humans
Group C--Possible human carcinogen (limited evidence of carcinogenicity 
in the absence of human data)
Group D--Not classifiable as to human carcinogenicity (inadequate human 
and animal evidence of carcinogenicity or no data available)
Group E--Evidence of non-carcinogenicity for humans (no evidence of 
carcinogenicity in at least two adequate animal tests in different 
species or in both adequate epidemiologic and animal studies).

    The weight-of-evidence basis was used to eliminate Group D and E 
constituents from further consideration as carcinogens. 

[[Page 66353]]

    Under each of the regulatory options presented in today's proposal, 
the Agency is using the same risk level for Groups A, B, and C 
carcinogens. This approach is consistent with the way carcinogens were 
treated in the 1990 Toxicity Characteristic rule, hazardous waste 
listing determinations, and the delisting program. The rationale for 
this approach is that while the classifications indicate the type 
(human or animal) and strength of the studies available which reflects 
upon the uncertainty about the carcinogenic potential, the severity of 
the effect, cancer, warrants equal treatment. It is important to note 
that a few Group C carcinogens do not have slope factors or unit risks. 
In these cases the Agency used the benchmark developed for the non-
cancer endpoint.
c. Consideration of MCLs
    The Agency is proposing two approaches for setting human health-
based levels for carcinogens and non-carcinogens in routes of exposure 
involving water ingestion. For the first approach, the Agency is 
proposing to use Maximum Contaminant Levels (MCLs) promulgated under 
the Safe Drinking Water Act (SDWA) of 1974, as amended in 1986, as the 
human health-based levels for the constituents for which they have been 
established. In general, MCLs for non-carcinogens are derived from the 
Reference Doses (RfDs), while MCLs for most carcinogens are set as 
close to zero as technically and economically feasible; this normally 
corresponds to risk levels that range from 10-4 to 10-6. 
(Note that, although the derivation of MCLs considers feasibility of 
treatment, analytic chemistry, and cost factors in addition to health 
effects, it also considers other routes of exposure. The Agency's 
policy has been to use MCLs, when available, in other similar 
concentration-based programs.) For those constituents which do not yet 
have MCLs, the Agency is proposing to use oral reference doses (RfDs) 
for non-carcinogens and oral slope factors for carcinogens as described 
above. However, if new MCLs are finalized under the SDWA prior to the 
promulgation of today's rule, the Agency proposes to substitute the new 
MCLs for the RfDs and slope factor-derived human health-based levels 
for water ingestion presented in today's notice.
    For the second approach, the Agency intends to propose to use only 
RfDs and slope factors in deriving human health-based levels for water 
ingestion. The Agency requests comment on these two approaches.
2. Ecological Benchmarks
    Ecological benchmarks were developed for a variety of ecological 
receptors based on the availability of data. Benchmarks were needed for 
mammals, birds, plants, soil fauna, fish, aquatic invertebrates, 
aquatic plants, and benthos (sediment-dwelling organisms). A much 
smaller number of constituents have been evaluated by the Agency for 
ecological effects than have been for human health effects, as 
discussed under V.A. In general, measurement endpoints were selected: 
(1) For consistency with the Agency's Framework for Ecological Risk 
Assessment (U.S. EPA 1992x), the Great Lakes Initiative, and other 
ecological efforts within the Agency, and (2) relevance to the 
ecological receptor. As discussed in ``Section D--Risk Assessment'' the 
ecological assessment focussed on inferring the sustainability of 
populations and communities within ecosystems. Therefore, benchmarks 
were derived from measurement endpoints (i.e., reproductive, 
developmental, growth, survival, and mortality) from which such 
inferences could be made. Reproductive studies (e.g., number of viable 
young per female) were preferred over other endpoints. For some 
constituents, acute or mortality studies were used, however, this 
occurred only for developing benchmarks for fish, aquatic 
invertebrates, and benthos where protocol exists (AWQC development) for 
using such data. The Agency seeks comment on the measurement endpoints 
selected for each ecological receptor.
    The toxicological benchmarks were established using the more 
conservative no effects level (or concentration) approach for 
ecological receptors as compared to a 20% effects level. The 20% 
effects level is the lowest level for ecological effects that can be 
detected in field population analyses (Suter et al., 1992). Although 
the 20% effects level may indeed be the lower limit that could be 
reliably confirmed in field studies, this level reflects our current 
analytical abilities and not necessarily the ecological significance of 
the effects level. The no effects approach was taken because the 
ecological analysis infers the sustainability of various populations 
under the assumption that if a sufficient number of populations within 
an ecosystem is protected, then the likelihood of adverse effects that 
are causally related to the chemical stressor will be reduced at the 
ecosystem level. The Agency was concerned that if an effects approach 
was taken, then the assumption underlying the ecological analysis would 
no longer be valid. The Agency seeks comment on the approach taken for 
setting toxicological benchmarks.
    Given the number and variety of ecological receptors included in 
the analysis (predatory birds to soil fauna) as well as the variety of 
effects and endpoints considered, the benchmark development process 
required an approach that was internally consistent and acknowledged, 
at least qualitatively, the uncertainty involved in estimating 
ecological benchmarks. The Agency, therefore, developed a benchmark 
classification scheme to incorporate both the relationship of the 
benchmark to the entire toxicity data set and the adequacy of the 
database used to derive the benchmark. Three classifications were 
established: Adequate, provisional, and interim. These classifications 
were developed on a receptor group-specific basis (i.e., fish and 
aquatic invertebrates, benthos, mammals, birds, soil fauna, and 
terrestrial plants) and represent a weight-of-evidence designation for 
the toxicological benchmark. In many respects, this classification 
scheme is similar in meaning to the human carcinogen weight-of-evidence 
groups and the difference between ``verified'' values on IRIS and 
``unverified'' values in HEAST. The classifications relate to the 
certainty assigned to a given ecological benchmark. The benchmarks were 
treated the same in the analysis regardless of classification. See 
Section 4 in the ``Technical Support Document for the Hazardous Waste 
Identification Rule: Risk Assessment for Human and Ecological 
Receptors'' for details on each classification and how they were used 
for each ecological receptor group. The Agency seeks comment on the 
classification developed for the analysis.
    Below is a discussion of how benchmarks were developed for each of 
the receptor groups. For a detailed discussion of each of their 
developments, see Section 4, ``Benchmarks,'' and Appendix B, 
``Toxicological Profiles for Ecological Receptors,'' of the ``Technical 
Support Document for the Hazardous Waste Identification Rule: Risk 
Assessment for Human and Ecological Receptors.'' The Agency seeks 
comment on the overall development of each of the ecological benchmarks 
generated for this proposed rule.
    For populations of birds and mammals, the overall approach used to 
establish toxicological benchmarks was similar to the methods used to 
establish RfDs for humans as described in IRIS. Each method uses a 
hierarchy for the selection of toxicity data (e.g., no effects 

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levels are generally preferred to lowest effects levels) and 
extrapolates from a toxicity benchmark for the test species to a 
toxicity benchmark for the desired species. However, the procedures 
used to develop benchmarks (i.e., RfDs) for the protection for human 
health establish an acceptable daily dose for all individuals 
(including sensitive sub-populations) while the development of 
ecological benchmarks for this analysis establish a level that will 
sustain the reproductive fitness in a local population. Consequently, 
benchmarks for birds and mammals were established using three key 
guidelines. First, because the reproducing population was selected as 
the assessment endpoint, the benchmarks were developed from measures of 
reproductive success or, if unavailable, other effects that could 
conceivably impair the maintenance of the population.
    Second, the taxon of the test species was matched to the taxon of 
the wildlife species to the greatest extent possible. The evolutionary 
processes that result in obvious differences in taxa (e.g., morphology) 
also result in differences in the physiological processes that govern 
chemical response. Moreover, taxonomic similarities are generally 
associated with similarities in feeding habits, physiology, and 
chemical sensitivity at the family classification and, to a lesser 
extent, the order classification. For example, herbivores are generally 
more resistant to toxicants than predators because they are exposed to 
plant toxins, and the enzymatic system that detoxifies plant toxins 
also detoxifies pesticides and other organic chemicals.
    Third, a default safety factor of 10 was adopted only for 
extrapolating from an lowest-observed-effects level (LOEL) to a no-
effects level (NOEL). A ten-fold safety factor was not applied to sub-
chronic studies since reproductive and developmental toxicity studies 
are frequently short-term. Even among target organ toxicity studies, 
there are many instances where sub-chronic studies are actually more 
sensitive than chronic studies carried out on the same substance. Also, 
for mammals and birds, differences in interspecies uncertainty were 
indirectly addressed through the use of the species-scaling equation 
described in Section 4 of the ``Technical Support Document for the 
Hazardous Waste Identification Rule: Risk Assessment for Human and 
Ecological Receptors.'' The Agency requests comment on the use a safety 
factor of 10 when extrapolating from a LOEL to a NOEL. The Agency also 
requests comment on the use of a scaling approach to address 
interspecies uncertainty as described above. Furthermore, the Agency 
seeks comment on the inability of the Risk Assessment to evaluate the 
inhalation and dermal routes of exposure for birds and mammals.
    For the terrestrial plants, the approach used to establish 
toxicological benchmarks was adapted from the Effects Range Low (ER-L) 
approach developed by the National Oceanographic and Atmospheric 
Administration (NOAA). The NOAA ER-L approach estimates a percentile of 
the distribution of various toxic effects thresholds. The measurement 
endpoints were generally limited to growth and yield parameters because 
(1) they are the most common class of response reported in 
phytotoxicity studies and, therefore, will allow for benchmark 
calculations for a large number of constituents, and (2) they are 
ecologically significant responses both in terms of plant populations 
and, by extension, the ability of producers to support higher trophic 
levels. It should be noted that these benchmarks were limited to soil 
concentrations and do not explicitly consider the adverse impacts on 
plants from ambient contaminant concentrations in the air. Further 
details can be found in section 4.3.3 of the ``Technical Support 
Document for the Hazardous Waste Identification Rule: Risk Assessment 
for Human and Ecological Receptors.'' The Agency solicits comment on 
the overall approach taken to develop benchmarks for the terrestrial 
plant community.
    For the soil fauna, the toxicological benchmarks were established 
based on methods developed by the Dutch National Institute of Public 
Health and Environmental Protection (RIVM). The RIVM approach estimates 
a confidence interval containing the concentration at which the no 
observed effects concentration (NOEC) for p percent (95th percentile 
was selected) of the species within the community is not exceeded 50% 
of the time. A minimum data set was established in which key structural 
and functional components of the soil community (e.g., decomposer and 
grazing organisms) encompassing different sizes of organisms (i.e., 
microfauna, mesofauna, macrofauna) were represented. As with the 
Ambient Water Quality Criteria, measurement endpoints included 
reproductive effects as well as measures of growth, survival, 
mortality. The Agency requests comment on the use of the RIVM 
methodology, and protecting 95 percent of the community 50 percent of 
the time. The Agency also requests comment on its inability to fully 
quantify the effect of soil characteristics on toxicity of constituents 
to soil organisms.
    For populations of fish and aquatic invertebrates (represented by 
daphnids), a hierarchical approach was taken for use of data sources in 
deriving benchmarks. The first choice was final chronic values (FCVs) 
from the Sediment Quality Criteria effort by the EPA Office of Water, 
followed by values from the Great Lakes Initiative (GLI) effort, and 
finally, the Ambient Water Quality Criteria (AWQC). If these benchmarks 
were not available, then a benchmark was developed using AWQC 
procedures or, if data were inadequate, the GLI Tier II procedures for 
establishing chronic values (termed secondary chronic values--SCVs). 
The AWQC ranked third since many years have passed since their 
establishment and the SQC and GLI efforts re-evaluated the toxicity 
data sets of several of these. The Agency solicits comment on the 
hierarchical approach described above for deriving toxicity benchmarks.
    For aquatic plants, the approach used to establish toxicological 
benchmarks was adapted from the ER-L approach developed by NOAA. The 
NOAA ER-L approach estimates a percentile of the distribution of 
various toxic effects thresholds. However, due to the general lack of 
toxicity data, the default ER-L approach was used wherein the lowest 
LOEC for either vascular plants or algae was used. The Agency solicits 
comment on the overall approach taken to develop benchmarks for aquatic 
plants.
    For the sediment organisms, the approach used to establish 
toxicological benchmarks for non-ionic, hydrophobic organic chemicals 
was based on sediment quality criteria methods for non-ionic 
constituents. Two key assumptions form the basis for the proposed 
sediment quality criteria. First, benthic species, defined as either 
epibenthic or infaunal species, have a similar toxicological 
sensitivity as water column species. As a result, FCVs (or SCVs) 
developed for the fish and aquatic invertebrates can be used for the 
benthic community. Second, pore water and sediment carbon are assumed 
to be in equilibrium and the concentrations are related by a partition 
coefficient, Koc. This assumption, described as equilibrium 
partitioning (EqP), provides the rationale for the equality of water-
only and sediment-exposure-effects concentrations on a pore water 
basis: The sediment-pore water equilibrium system results in the same 
effects as a water-only exposure. The Agency requests comment on the 
use of this approach in support of today's proposal. In some cases, 
protecting these 

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ecological receptors represents the critical pathway that limits the 
projected exit level for management of a waste stream outside of the 
Subtitle C hazardous waste program. These ecological receptors serve as 
the basis for the proposed exit levels for 18 constituents, including 6 
metals. To the extent that contaminants from these waste streams reach 
off site areas, the Agency based its proposal on modeling the 
ecological receptors on a neighboring land area of 500 acres or an 
adjacent stream (with a total length of 12 miles). This approach as 
currently modeled, may only serve as an indicator of a potential nearby 
threat to ecological receptors (e.g., the soil fauna and plant life), 
rather than serving as a measure or indicator of a broader threat to 
the environment. The Agency solicits comment on the appropriateness and 
relevance of these receptors as the basis for exit levels under the 
HWIR program.
3. Sources of Data
a. Human
    The two primary sources used to identify human health benchmarks 
were the Integrated Risk Information System (IRIS) and the Health 
Effects Assessment Summary Tables (HEAST). Both of these sources were 
developed and are maintained by the USEPA. For a few constituents, 
other Agency sources such as Carcinogen Assessment Group (CAG) 
profiles, Health Effect Assessments (HEAs), and Health Assessment 
Documents (HADs) were used to fill data gaps.
    IRIS is the Agency's official repository of Agency-wide consensus 
chronic human health risk information. IRIS evaluation are conducted by 
the Agency's Work Group review process that leads to internal Agency 
scientific consensus regarding risk assessment information on a 
chemical. This information is recorded on IRIS and is considered to be 
``Work Group Verified.''
    The HEAST is prepared by EPA's Office of Research and Development. 
They contain risk assessment information on chemicals that have 
undergone a more limited review and have the concurrence of individual 
Agency program offices; each is supported by an Agency reference. The 
information has not, however, had enough review to be recognized as 
Agency-wide consensus information.
b. Ecological
    A thorough literature review was conducted to identify 
toxicological data from laboratory and field studies for each of the 
constituents of ecological concern. The review included secondary 
sources such as the Synoptic Review Series published by the U.S. Fish 
and Wildlife Service, the Ambient Water Quality Criteria documents, and 
other Federal compendia of toxicity data (e.g. HEAs, the Derivation of 
Proposed Human Health and Wildlife Bioaccumulation Factors for the 
Great Lakes Initiative, Agency for Toxic Substances and Disease 
Registry documents, PHYTOTOX, GRIN, TERRETOX, and AQUIRE). Toxicity 
data on soil organisms were obtained for several constituents from van 
de Meent et al. (1990). In addition to AQUIRE, the other primary data 
source for toxicity data on aquatic plants were the Toxicological 
Benchmarks for Screening Potential Contaminants of Concern for Effects 
on Aquatic Biota:1994 Revision (Suter and Mabrey, 1994). On-line 
literature searches were conducted to identify primary sources of 
toxicity data on constituents lacking sufficient data in the secondary 
sources. Additional studies were identified in conventional literature 
reviews.

E. Risk Assessment

1. The Non-groundwater Risk Assessment
a. Introduction
    The risk assessment underlying today's proposed rule is based upon 
a comprehensive approach to evaluating the movement of many different 
waste constituents from their waste management units, through different 
routes of exposure or pathways, to the points where human and 
ecological receptors are potentially exposed to these constituents. 
This risk assessment is being used in today's proposed rule to 
determine which listed hazardous wastes can be defined as ``low-risk'' 
wastes, able to exit the Subtitle C system and be managed in non-
Subtitle C units. The previous approach taken in the May 20, 1992, 
proposed HWIR rule also addressed the risks associated with the 
management of wastes containing hazardous constituents with very 
diverse physical and chemical properties; however, only groundwater 
ingestion exposures from landfill units were evaluated. That approach 
led to a concern by the Agency, as well as commenters on the proposed 
rule, that leachate from landfills contaminating groundwater and 
subsequent consumption of the contaminated groundwater by humans may 
not be the only exposure pathway important to evaluate. Although the 
ingestion of contaminated groundwater pathway may be appropriate to 
propose exit levels for some wastes and constituents, it may be under-
protective for others, depending on the physical and chemical 
properties of each waste constituent. (For example, some constituents 
have a high potential to bioaccumulate or bioconcentrate in living 
organisms. Pathways in which these constituents come in contact with 
fish, grazing livestock, wildlife, or edible plants would be important 
to evaluate.) In addition, over the past 14 years of implementing the 
RCRA program, the Agency has learned more about potential routes of 
release to the environment from various management practices.
    Therefore, for today's proposal the Agency undertook an extensive 
risk assessment that examines numerous exposure pathways, rather than 
just the groundwater ingestion pathway. In selecting the exposure 
pathways, previous rulemakings were used as a guide, as well as other 
special studies by the Agency that implement analyses examining 
numerous pathways. (Tables A-1 and A-2 contain the human and ecological 
pathways, respectively, evaluated in the assessment, and are presented 
in appendix A to today's preamble.) With regard to waste management 
units considered in the assessment, it is important to note that 
because today's proposal establishes criteria for waste to exit the 
Subtitle C system, the assessment evaluated exposures associated with 
managing wastes in non-Subtitle C units. The human and ecological 
receptors considered in the assessment were selected to represent a 
range of behaviors, activities, dietary habits, and trophic levels that 
influence exposure levels.
    The risk assessment supporting this proposal is currently 
undergoing review by the Science Advisory Board and EPA's Office of 
Research and Development. As a result of these reviews, and of comments 
received during the public comment period, it is likely that EPA would 
make changes to the risk assessment or other parts of the rule. Topics 
on which the Agency has received informal comment include the use of 
ecological benchmarks for regulation and the overland transport of 
waste constituents. The Agency, to the extent consistent with the 
schedule negotiated in the consent decree for this rulemaking, would 
publish a supplemental notice proposing any significant changes before 
finalizing the rule.
b. How the Assessment is Structured
    The non-groundwater assessment acknowledges that not all human and 
ecological pathways arise from each 

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source; for example, movement of particles from an active surface 
impoundment is not expected to occur. To account for this, the 
assessment matched the environmental transport pathways with both the 
releases from various types of waste management units and the various 
receptors for the nearly 200 constituents examined. All constituents 
were assessed in all pathways deemed plausible for a given waste 
management unit, if the data permitted. Tables A-3, A-4, and A-5 of 
appendix A show the pathways assessed for each waste management unit, 
human receptors assessed for each pathway, and ecological receptors 
assessed for each pathway, respectively. The assessment estimated the 
constituent-specific concentrations in a waste at the management unit 
that could be expected to result in an acceptable exposure for a human 
or ecological receptor (determined through using the toxicity 
benchmarks discussed in section V.B.), taking into account the various 
pathways by which the constituent may move through the environment from 
the waste management unit to the receptor.
    The waste management units considered in the assessment are not 
all-inclusive but were selected to reflect those that might be commonly 
associated with the management of exited hazardous wastes (from 
wastewaters to nonwastewaters) in non-Subtitle C waste management 
units. These units were identified as commonly used in the management 
of solid wastes in the 1988 Report to Congress entitled Solid Waste 
Disposal in the United States Report. The Agency believes that risks 
posed by other types of management of these exited wastes will be no 
greater than those from the units assessed.
    There is a high degree of variability in the physical and chemical 
properties of the approximately 200 constituents evaluated. An 
understanding of those properties and how they interact with the 
physical and chemical properties that control persistence and mobility 
in the environment is an essential element of the assessment. The 
management units could potentially be located in the range of 
environments that exist across the United States. These environments 
have differing characteristics (e.g., meteorological conditions, soil 
type) that are more conducive for the movement of certain constituents 
in certain pathways than others. For example, an environment with a 
high precipitation and high organic soil content may result in 
significant exposures to fishers by constituents that readily adsorb to 
soils (i.e., have a high log Kow) through erosion of contaminated 
soil and uptake in the food chain. For other pathways, however, an 
environment with these characteristics may result in relatively low 
exposures. The assessment was designed to determine what conditions 
would need to exist to cause higher exposures for each pathway rather 
than developing a scenario and determining all the types of exposures 
and receptors for that scenario. By determining the appropriate 
conditions for which higher exposures from a given pathway will occur, 
the Agency believes that environments where the conditions are not as 
likely for a constituent to move through a pathway are protected.
    The assessment was structured using a deterministic approach. A 
deterministic approach uses a single, point estimate of the value of 
each input or parameter and calculates a single result based on those 
point estimates. The assessment used the best data available to select 
typical (i.e., approximately 50th percentile) and high-end (i.e., 
approximately 90th percentile) values for each parameter or parameter 
group as discussed in Section E.2. below. Sometimes full distributions 
were available but, more commonly, ranges of values or point values 
were available with no description of distributions or variability. If 
there was not a sufficient distribution for the parameter, best 
professional judgement was used in determining typical and high-end 
values (which sometimes would be the maximum).
     The assessment is constructed as a set of calculations that begin 
with an acceptable exposure level for a constituent at a receptor, and 
back-calculates to a concentration in a waste in a management unit that 
corresponds to the acceptable exposure level. For the human receptors, 
the assessment was designed to determine constituent concentrations in 
waste for each waste management unit that would correspond to 
protecting receptors at the high-end of exposure (i.e., above the 90th 
percentile of each of the receptor populations and types of exposures 
being assessed). The Agency estimated waste concentrations 
corresponding to the high-end exposure by identifying four critical or 
sensitive parameters in the source/pathway/receptor equations and using 
high-end input values for those parameters and using central tendency 
values for the remaining parameters. The Agency also estimated central 
tendency (approximately the 50th percentile) and bounding estimates 
(worst-case) of constituent concentrations in waste for each of the 
receptor populations and types of exposures being assessed. For 
ecological receptors, the approximate percentile level of protection is 
difficult to discern. The Agency believes the ecological analysis is 
conservative with respect to the overall assessment endpoint (e.g., 
sustainability of the reproducing populations) because of the way the 
source, fate and transport parameters are set, the dietary habits 
assumed, and how the toxicity benchmarks are developed. However, the 
degree to which this conservativeness transfers to ecosystems is not 
known.
    The steps of the assessment which provide estimates of acceptable 
constituent-specific concentrations in waste include the following:
    Step 1--Specify acceptable risk levels for each constituent and 
each receptor. See Section V.B. in today's preamble for a discussion of 
how benchmarks are set for both human and ecological receptors.
    Step 2--Specify the exposure medium. Using the toxicity benchmarks 
as a starting point and the exposure equations, the assessment back-
calculates the concentration of contaminant in the medium (e.g., beef, 
milk, plant, air, water, soil) that corresponds to the ``acceptable'' 
exposure level. The exposure equations include a quantitative 
description of how a receptor comes into contact with the contaminant 
and how much the receptor takes in through specific mechanisms (e.g., 
ingestion, inhalation, dermal adsorption) over some specified period of 
time. Thus, for the subsistence farmer eating contaminated beef, the 
exposure specifies the amount of beef eaten on a daily basis, the 
period of time over which the contaminated beef is eaten, and 
descriptions for the individual such as body weight and lifetime. For 
this example, the concentration in the beef is what is back-calculated.
    Step 3--Calculate the point of release concentration from the 
exposure concentration. Based on the back-calculated concentration in 
the exposure medium (from Step 2), the concentration in the medium to 
which the contaminant is released to the environment (i.e., air, soil, 
groundwater) for each pathway/receptor was modeled. The end result of 
this calculation is a medium concentration at the point of release from 
the waste management unit.
    Step 4--Calculate the concentration in the waste that corresponds 
to the medium concentration at the point of release. This step depends 
on the characteristics (e.g., area, cover practices, waste consistency) 
of the waste management unit. 

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    The output of the assessment is a range of constituent 
concentrations, reflecting the range of pathway-receptor combinations 
considered for each waste management unit. The lowest concentration 
(per constituent) of this range represents the highest exposure 
pathway-receptor combination for that waste management unit.
c. How Uncertainty is Addressed
    Any analysis of the magnitude used in this rule-making will have 
uncertainty associated with the outputs generated. The uncertainty can 
be associated with the models or equations used and the data relied on 
for the model parameters. In addition, policy assumptions, such as 
waste management units assessed and receptors assessed, may also affect 
the degree of representativeness of the assessment. In order to be 
consistent with Agency policy on the characterization of risk, 
stochastic and deterministic approaches were considered. A stochastic 
approach, such as Monte Carlo analysis, which produces a distribution 
of constituent concentrations, was initially considered due to the 
tremendous interest in, and use of, these techniques in risk 
assessment. However, after evaluation of the models and data available 
for use, the Agency decided to use a deterministic approach for the 
non-groundwater assessment.
    The Agency's deterministic approach used for this assessment, like 
most such approaches, uses point values in all calculations and 
produced point estimates of constituent concentrations for waste in 
each management unit-exposure pathway-receptor combination. However, in 
selecting and developing point values for parameters, EPA considered 
all available data. Wherever possible, the Agency developed both a 
central-tendency and high-end value for each parameter used in the 
assessment. This was not possible in all cases because some parameters 
were a property, such as density of water, and because some values were 
fixed by Agency-wide policy decisions. (For example, EPA used standard 
Agency-wide human toxicity benchmarks and body weights.) EPA then 
calculated constituent concentrations based on a mixture of central-
tendency and high-end values.
    EPA believes that the deterministic approach described above (based 
on identifying critical parameters and using higher-end values only for 
those parameters and central-tendency values for the other parameters) 
allowed it to derive constituent concentrations in waste for each waste 
management unit that are reasonably protective across a range of 
conditions and for a range of receptors. EPA also believes that this 
approach is consistent with EPA's risk assessment policy.
    EPA further believes that the approach chosen allows both the 
Agency and the public to determine more easily which parameters played 
the most critical roles in determining the constituent concentrations 
in waste for each waste management unit. This furthers general 
understanding of the assessment and helps commenters effectively target 
their resources for reviewing what EPA is proposing. It has also helped 
EPA target its own data collection and input selection efforts. It is 
often more difficult to identify critical parameters in a stochastic 
assessment because of the greater number of iterations and because 
results are reported as probability distributions. This is particularly 
true for an analysis with a large number of parameters such as the 
assessment used for this proposed rule.
    EPA notes that stochastic approaches are also consistent with 
Agency risk assessment policy. In fact, EPA applied a stochastic 
``Monte Carlo'' approach to the separate analysis of dilution and 
attenuation of groundwater performed for this proposal. That analysis, 
however, has been under development for many years and EPA is more 
familiar with the underlying data and the relationships between various 
parameters. In addition, the public has had a chance to comment on 
aspects of that analysis in previous rule-makings. EPA was more 
comfortable applying a stochastic analysis for the groundwater analysis 
than a stochastic approach to the non-groundwater analysis.
    EPA believes that it is not necessary to resolve all issues 
relating to the relative merits of the two approaches or to determine 
which approach would be ideal for each of the assessments described 
above. Rather, the debate should focus on whether the approaches chosen 
allowed EPA to reach reasonable regulatory decisions.
    The Agency solicits comment on the use of a deterministic approach 
as described above. Specifically, the Agency seeks comment on whether 
the approach proposed is a reasonable approach for setting protective 
levels across a set of types of management units and exposure pathways.
d. Linkage of the Non-groundwater Risk Assessment to the Groundwater 
Risk Assessment
    In the non-groundwater risk assessment, the pathways involving 
potentially contaminated groundwater (e.g., bathing) are back-
calculated from the receptor to the wellhead (i.e., the assessment 
provides constituent concentrations in the groundwater at the well). In 
order to determine the concentration of a constituent in leachate 
coming from a waste management unit that would result in the estimated 
constituent concentration at the water well, the Agency used a separate 
groundwater fate and transport risk analysis. That analysis is 
described in detail in Section D.8. elsewhere in today's proposal. The 
well concentrations estimated from the pathways involving bathing are 
used as input to the groundwater fate and transport modeling from which 
a leachate concentration is determined.
e. Risk Targets Used
    As previously discussed in Section V.B. of today's proposed rule, 
the Agency used existing toxicity benchmarks when available. However, 
many ecological benchmarks were developed for this rule-making, as 
discussed in Section V.B. of today's proposed rule. As described in 
that section, the Agency used a cancer risk target of 1  x 10-6, 
and a hazard quotient equal to 1 for non-carcinogens. For ecological 
benchmarks, a hazard quotient equal to 1 was used. The Agency solicits 
comment on the risk targets being used for today's proposed rule.
2. Detailed Overview of the Non-groundwater Risk Analysis
    The assessment can be broken down into six components: 
Constituents; toxicity benchmarks; receptors; exposure; fate and 
transport; and waste management units. Each of these components is 
discussed in turn below, except the constituents and toxicity 
benchmarks which were discussed earlier in section V.A and V.B. It is 
important to recognize that the assessment was not able to evaluate all 
constituents in all receptor-pathway-waste management unit combinations 
because of data gaps in either toxicity or chemical properties, or 
inadequate methodologies. Many of these gaps have been identified in 
different sections of the Technical Support Document for the Hazardous 
Waste Identification Rule: Risk Assessment for Human and Ecological 
Receptors'' (denoted ``Uncertainties and Issues of Concern''). The 
Agency requests additional data or other information that would assist 
in filling these gaps.
a. Waste Management Units
    The manner in which constituents are released to environmental 
media and the relative quantity released to each 

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medium will affect the pathways of most concern for a particular 
constituent. The pathway presenting the highest risk to human or 
ecological receptors is not always easily determined because of the 
complex interactions of the waste management unit and its types of 
releases, the physical and chemical properties of the constituent, and 
the properties that control mobility and persistence in a particular 
environmental medium. For some constituents, the management practice 
will determine which exposure pathway is of most concern. For example, 
benzene tends to migrate to both air and groundwater. Upon examining 
the risks from exposure to these two media arising from releases from a 
quiescent surface impoundment, the groundwater ingestion pathway may 
pose the highest risks. But, when examining the risks from these two 
media for releases from an aerated tank, the air inhalation pathway may 
pose the higher risks. Further, the air inhalation risks may even be 
higher than groundwater ingestion risks from the quiescent surface 
impoundment.
    Therefore, and as stated earlier, the selection of non-Subtitle C 
waste management units examined in the assessment attempted to reflect 
both the influence of the type of unit on pathways and those that might 
be commonly associated with the management of exited hazardous wastes 
in non-Subtitle C waste management units. Again, the Agency believes 
that risks posed by other types of management of these exited wastes 
will be no greater than those from the units assessed. The management 
units examined include the following:
     Aerated treatment tanks. Relative to all other types of 
management, aerated tanks containing wastewaters can potentially have 
the most significant releases of volatile organics to air.
     Quiescent surface impoundments. This type of unit 
containing wastewaters also can potentially result in significant 
releases of volatile organic constituents to air. These units also have 
a potential to affect surface water bodies if the unit is not well 
maintained or constructed. The sludges generated, which may contain 
high concentrations of metals and hydrophobic constituents, may impact 
groundwater. (As discussed above, the groundwater fate and transport 
analysis was conducted in a separate analysis.)
     Land application. This type of unit, when used for non-
wastewaters can potentially have significant releases of certain 
constituents to nearby land and surface water bodies through erosion 
and runoff, particularly if run-on and run-off control measures are not 
practiced. In addition, significant releases of volatile organics 
constituents to air are possible. Further, after the unit is closed, 
significant on-site exposures to some persistent and relatively 
immobile constituents may occur as well as continued long-term releases 
to the nearby land and surface water bodies. The Agency believes such 
units will pose higher exposures relative to landfills in all pathways 
except those arising from groundwater. Therefore, the non-groundwater 
assessment did not examine landfills, but they were examined in the 
groundwater fate and transport analysis.
     Ash monofill. This type of unit used for ash disposal can 
potentially have significant releases of particulates to air which may 
be inhaled or may deposit on land and plants, and result in exposure 
through food and soil ingestion.
     Wastepiles. This type of unit used for nonwastewaters can 
have significant releases of particulates to air as well as significant 
releases of particulates through erosion and runoff.
    Each of the pathways that evaluates a receptor using contaminated 
groundwater other than as a source of drinking water (i.e., bathing) 
are back-calculated to a concentration in a drinking water well. The 
pathways are applicable to all of the waste management units modeled 
(except tanks). All of the waste management unit and chemical-specific 
portions of the groundwater fate and transport analysis and subsequent 
estimated leachate concentrations are contained in the Agency's 
separate groundwater fate and transport analysis (see Section E.3 
below).
    One exception to the above discussion of the types of waste 
management units evaluated involves the combustion of wastes. Although 
the Agency attempted to include this type of management in the 
assessment, it became clear that the emissions from combustion are not 
easily predicted from the waste inputs to the units. The combustion 
process both destroys and creates constituents. Although destruction of 
constituents can be predicted based on certain operating 
characteristics of combustion units, the creation of other 
constituents, referred to as products of incomplete combustion (PICs), 
is not easy to predict. It may be possible to make such predictions for 
a specific waste and a specific combustion unit; however, the extensive 
data (e.g., on the variety of combustion units, waste types, 
constituent combinations) needed for the assessment used in this 
rulemaking relating wastes with emissions are not available. Therefore, 
acceptable constituent levels in waste going to a combustion unit could 
not be established. However, the Agency is developing emission 
standards for various types of combustion units and those emission 
standards may be a more appropriate vehicle for addressing combustion.
    In addition, the assessment does not address accidental or 
catastrophic releases, such as transportation accidents or tank 
failures. The Agency determined that, although such releases are 
possible, they are of low probability and non-routine and, therefore, 
are not appropriate for developing exit criteria that apply to all 
wastes.
    The Agency has identified several specific areas giving rise to 
uncertainty in the characterization of the waste management units and 
for which the Agency seeks comment:
    (1) Use of Subtitle D Survey.
     The Agency relied upon data from a 1987 survey of Subtitle 
D facilities to characterize waste management units. That survey, used 
in the 1988 Report to Congress on Solid Waste Disposal in the United 
States, was designed primarily to collect estimates of the following 
parameters:
     Number of establishments that manage Subtitle D wastes on 
site;
     Number of establishments that manage Subtitle D wastes on 
site in land application units, wastepiles, surface impoundments, or 
landfills;
     Number of land application units, wastepiles, surface 
impoundments, or landfills used to manage Subtitle D wastes;
     Amount of Subtitle D wastes managed on site in land 
application units, wastepiles, surface impoundments, or landfills.
    In addition to these parameters, data were also collected for some 
other parameters, such as the area of the waste management units. 
Although the survey was not designed to collect accurate estimates for 
these other parameters, it is the most comprehensive date available to 
characterize these other parameters. One difficulty encountered in 
using these data is that the survey requested information on total area 
or waste quantity for all of each type of units at a facility. The 
total area or waste quantity was divided by the number of each type of 
unit at the facility (number of each unit being one of the primary 
parameters the survey was designed to estimate) to estimate average 
unit area. Further, it is not certain how well the on-site units (which 
are used routinely for wastes generated on-site) reflect the 
characteristics of off-site units. Uncertainty related to the 

[[Page 66359]]
representativeness of the data is important because exited wastes could 
be managed in units off-site as well as on-site. The Agency seeks 
comment on the use of the Subtitle D survey to characterize the waste 
management units.
    In evaluating the waste management unit components of the risk 
assessment, the Agency made certain assumptions when data were not 
available or were incomplete. A description of the waste management 
unit parameters for which there was little to no data is described 
below. The rationale behind these assumptions is presented (e.g., 
results of any sensitivity analyses, references to other work, etc.). 
The Agency requests comment on the specific issues raised for each 
management unit.
(2) Fate and Transport
    Fate processes, particularly biodegradation and hydrolysis, were 
accounted for only in the land application unit since that unit had 
wastes applied intermittently and that unit was being examined for on-
site risks after closure (assuming human occupation of the site begins 
10 years after closure occurs). Because waste is continuously applied 
to the other waste management units, biodegradation and hydrolysis were 
presumed to have minimal influence on the subsequent availability of 
constituents to the above ground pathways. The Agency requests comment 
on not considering biodegradation and hydrolysis in waste management 
units other than the land application unit. The Agency also requests 
comment on the appropriateness of the data and methods used to account 
for the fate and transport of constituents in waste management units, 
with particular emphasis on data and methods of determining 
biodegradation and hydrolysis of constituents in land application 
units.
(3) Ash Monofill
(i) Particle Size Distribution for Air Dispersion Modeling
    A size distribution of ash particles that become airborne from an 
ash monofill was not available. Therefore, a sensitivity analysis was 
performed to assess the importance of the particle size distribution in 
the calculation of air concentrations and deposition rates. Different 
distributions were modeled reflecting a variety of assumptions for 
particle size distributions between PM10 and PM30 classes. The greatest 
deviation among the modeled conditions in the estimated air 
concentration of PM10 was 12 percent; for the estimated deposition rate 
for PM30 the greatest deviation was 59 percent. Given the uncertainties 
and variabilities inherent in the assessment, these variations were 
considered minor, therefore, the Agency assumed an equal distribution 
of particle sizes between the two size classes used in the assessment.
(ii) Monofill Characterization
    Because limited data were available to characterize hazardous waste 
ash monofills, data from municipal waste ash monofills were used. 
However, because ash generation rates for municipal waste incinerators 
ere more than 100 times greater than ash generation rates for hazardous 
waste incinerators and reuse-as-fuel combustors resulting in 
significantly larger municipal monofills, EPA calculated an ash 
monofill volume for this analysis based on generation rates reported in 
the 1988 National Survey of Hazardous Waste Treatment, Storage, 
Disposal, and Recycling Facilities, assumed bulk density of the ash, 
and assumed lifetime of the monofill. The Agency is not certain that 
hazardous waste monofills should be sized in the same manner as 
municipal waste monofills. The Agency also assumed that each waste 
monofill would accept ash from only a single combustor. Accepting 
wastes from more than one combustor may underestimate monofill size.
(iii) Vehicle Traffic
    The estimates of number of ash trucks per day are dependent on the 
size of truck. Limited data were available on the sizes of trucks 
hauling ash. These data were used to characterize a range of truck 
sizes. The truck sizes may either under- or overestimate the size of 
trucks actually used at hazardous waste ash monofills depending on the 
representativeness of municipal waste ash truck sizes.
    No data were available on other vehicular traffic; therefore, these 
values were estimated, introducing additional uncertainty into the 
overall amount of traffic at the ash monofill.
(iv) Emission Equations for Ash Blown From Trucks and During Spreading 
and Compacting
    The emission equation used for ash blown from trucks was developed 
for windblown emissions from storage piles. This was adapted to trucks 
by using the truck speed to estimate frequency of wind greater than 5.4 
m/s. Because this equation was not derived for windblown emissions from 
moving trucks, the results of its application to such emissions are 
uncertain. It may over- or underestimate actual emissions of 
particulates blown from trucks.
    Similarly, the emission equation used for spreading and compacting 
was developed for agricultural tilling. Agricultural tilling was 
thought to approximate the process of spreading and compacting; 
however, the use of this equation may under- or overestimate emissions 
due to spreading and compacting.
(4) Land Application Unit
(i) Particle Size Distribution for Air Dispersion Modeling
    A size distribution of soil particles that become airborne was not 
available. The same assumption was made for soil particles as was done 
for ash particles when modelling the monofill (see above). As described 
above for ash particles, the Agency assumed an equal distribution of 
particle sizes between the two size classes.
(ii) Area of Land Application Unit Relative to Agricultural Field
    The assessment examined the impact of subsistence farming on the 
land application unit beginning 10 years after closure. Based on the 
distribution of sizes for land application units and agricultural 
fields, the Agency selected a combination of fields such that the 
central tendency land application unit (61,000 m2) is smaller in 
area than the central tendency agricultural field (2,000,000 m2). 
The significantly larger size of the agricultural field suggests that 
the model may inappropriately average the constituent concentration 
over the agricultural field. However, the Agency does not believe this 
to be a significant impact on the analysis because: (1) The area of the 
agricultural field is not an explicit input to the model; (2) the size 
of the land application unit is large enough to support a subsistence 
farmer; and (3) this pathway is driven by the assumptions for the high-
end analysis. The Agency requests comment on the relationship between 
the land application unit and the agricultural field.
(iii) Application Rate
    The waste application rate is an important parameter in determining 
the constituent's soil concentration after application. In practice, 
this rate is a function of the characteristics of the waste being 
applied, the characteristics of the receiving soil, the environmental 
conditions, and the purposes for which the waste is being applied. 
Information from the Subtitle D survey was used to calculate the rates, 
since those rates 

[[Page 66360]]
were not expressly requested in the survey. The rates were calculated 
from the area receiving the wastes and the waste quantity applied. This 
introduces uncertainty for it combines rates applicable to both 
treatment of wastes and rates for specific uses (e.g., farming, mine 
reclamation). To account for the potential of having application rates 
be much too high for the site they are being applied to, the data on 
receiving area and waste quantity applied were linked.
(iv) Waste Characteristics
    Limited data were available on the characteristics of wastes being 
land applied. As a result, soil values for most parameters (e.g., 
hydraulic conductivity, moisture retention index) were used to 
characterize nonwastewaters. It is not known to what extent these soil 
values differ from the waste properties.
(v) Depth of Contamination
    Depth of contamination affects the amount of constituent available 
for exposure. For the non-groundwater pathways, only constituents at 
the soil surface were assumed available for each exposure pathway. The 
Agency selected tilling depth as the depth of contamination available 
to the non-groundwater pathways as over time, the depth of the waste 
layer would increase and a portion of the mass of waste would move out 
of the zone available for the surface pathways. The model kept the 
depth of contaminated soil constant that was available for the surface 
pathways. The Agency recognizes that the use of the tilling depth may 
underestimate the depth of contamination in some cases and overestimate 
it in others. Thus, the Agency requests comment on the use of tilling 
depth as a surrogate for depth of contamination.
(vi) Partitioning
    Releases from the land application unit were partitioned among 
volatilization, evaporative losses, hydrolysis, erosion, runoff, and 
leaching. Periodic application of waste was factored into the 
partitioning model during the active life of the unit. Biodegradation 
was factored in during both the active life and closed period. The 
finite source Jury model was used to estimate volatilization emissions. 
The Jury model, which models the convection of constituents caused by 
the flux of water in soil, was used for evaporative losses. Runoff and 
leaching losses were calculated using the soil-water partition 
coefficient (Kd) to determine constituent concentration in the 
soil water and multiplying that by the land application unit area and 
runoff rate for run-off losses or recharge rate for leaching losses. 
(See Technical Support Document for the Hazardous Waste Identification 
Rule: Risk Assessment for Human and Ecological Receptors, Section 7, 
Land Application for full description.)
(5) Waste Pile
(i) Waste Pile Height
    No data were available on this parameter; therefore, the value is 
an estimate based on heights attainable by a front-end loader. This 
parameter is important in the air dispersion modeling, which is 
sensitive to the height of the pile. The Agency requests suggestions 
for alternatives to determining waste pile height and any data which 
would support those determinations.
(ii) Particle Size Distribution for Air Dispersion Modeling
    The same sensitivity analysis and assumptions discussed above for 
ash monofills were used for waste piles. Given that the air dispersion 
analysis is not very sensitive to particle size distribution, the 
simple assumption described above was believed to be an adequate 
approximation for the assessment.
(iii) Waste Characteristics
    Limited data were available on the characteristics of wastes in 
waste piles. As a result, soil values for most parameters (e.g., 
hydraulic conductivity, moisture retention index) were used to 
characterize the nonwastewaters disposed in piles. It is not known to 
what extent these soil values differ from the waste properties. The 
soil values, however, were not used for the ash waste pile. The ash 
disposed in the piles had the same properties as that disposed of in a 
monofill.
(iv) Vehicle Traffic
    The estimates of number of trucks per day are dependent on the size 
of truck and waste quantity. Limited data were available on truck 
sizes. These data were used to characterize a range of truck sizes. 
These truck sizes may either under- or overestimate the size of trucks 
actually used around waste piles.
(v) Emission Equation for Ash Blown from Trucks
    As described in the section above on ash monofills, the emission 
equation used for ash blown from trucks was developed for windblown 
emissions from waste piles. It may over- or underestimate actual 
emissions of particulates blown from trucks.
(6) Surface Impoundment
(i) Two-Phase Sludge Formation Model
    The two-phase sludge formation model simplifies the solids 
concentration gradient in a surface impoundment into two distinct and 
homogeneous layers, a liquid layer with the same average solids content 
as the inflow and a sediment or sludge layer with a much higher solids 
concentration.
(ii) Dilution of Waste During a Spill
    Overflows or breaches associated with surface impoundments are a 
waste release examined in the assessment. The algorithm used for spills 
does not account for dilution of the wastewater caused by excess run-
on. Such run-on is presumably relatively uncontaminated; thus the spill 
volume, consisting partly of contaminated wastewater from the 
impoundment and partly of uncontaminated run-on would have a lower 
concentration than the wastewater in the impoundment. By using the 
concentration in the impoundment, the mass of contaminant released to 
surface water is overestimated. This effect could be considerable for 
the central tendency impoundment, as the quantity of run-on is 
significant compared to the capacity of the central tendency 
impoundment. However, to determine the extent of such dilution, the 
degree to which such run-on becomes mixed with the wastewater would 
need to be estimated. No model has been found to assist in this 
estimation.
(7) Tank
(i) Unit characterization
    Limited data were available on Subtitle D tanks. The assessment 
used the profiles (specifies design and operating parameters) for 
uncovered aerated treatment tanks developed in the Hazardous Waste 
TSDF--Background Information for Proposed RCRA Air Emission Standards 
(TSDF--BID, U.S. EPA, 1991)
(ii) Volatilization
    The Agency used the well-mixed flow model. This model assumes that 
the contents of the system are well mixed and that the equilibrium 
concentration in the system is equal to the effluent concentration. The 
equilibrium concentration is the average concentration throughout the 
unit and the driving force for volatile emissions.
(8) Combustors
    For the reasons stated below, EPA did not modelled a combustion 
unit in the risk analysis for this regulation. EPA, 

[[Page 66361]]
however, asks for comments on that decision.
    In initial analyses (see Multipathway Analysis Background Document 
available through the docket), EPA modeled potential risks from several 
types of combustion units, using engineering judgment to make a best 
estimate for destruction and removal efficiencies for non-hazardous 
waste combustors. Early comments suggested that the assumptions might 
have overstated or understated the estimated risks by not reflecting 
actual practice in industrial boilers or other likely combustion 
facilities not regulated by Subtitle C. However, initial comparisons 
indicated that the combustion risk estimates back-calculated to the 
combustion unit were not often the most significant risk and, 
therefore, would not be the basis for the limiting exit criteria.
    EPA also recognized that there are many issues related to organics 
that are produced during the combustion process, but are not 
necessarily originally in the waste. The amount and type of these 
``products of incomplete combustion'' are generally believed to be 
dependent on a number of aspects of the design and operation of a 
facility, and not easily related to the composition of the wastes fed 
into the combustion unit. For purposes of this proposal, EPA decided 
that because of the high degree of uncertainty associated with 
developing waste concentrations from combustion units, it was not 
appropriate to use risks from combustion as a factor in deciding what 
wastes remain under the hazardous waste regulations. Rather, EPA 
believes there are more appropriate ways to regulate emissions from 
combustion units through various regulatory authorities, including 
regulation of a range of units under the Clean Air Act.
    EPA, however, asks comment on the appropriateness of this approach. 
In particular, there may be some constituents (e.g., certain metals 
that are difficult to capture in pollution control equipment) where a 
better correlation exists between waste input and potential risk from 
combustor emissions than for organics that are in the waste and also 
created as PICs during the combustion process.
b. Fate and Transport
(1) Pathways
    In selecting environmental fate and transport pathways to include 
in the assessment, EPA used as a guide previous rulemakings and other 
special studies by the Agency that examine numerous pathways. For 
example, the Agency has used similar risk assessment methodologies in 
several recent rules including: Wastes from Wood Surface Protection, 
Final Rule (59 FR 458, January 4, 1994); Standards for Use or Disposal 
of Sewage Sludge, Final Rule (58 FR 32, February 19, 1993); Corrective 
Action Management Units, Final Rule (58 FR 29, February 16, 1993); and 
rulemaking efforts on the Pulp and Paper Industry (56 FR 21802, May 10, 
1991 and 58 FR 66078, December 17, 1993).
    The sewage sludge and pulp and paper rulemakings in particular 
examined both human and ecological risk. Other rulemakings under 
development within the Office of Solid Waste also use non-groundwater 
risk assessment methodologies including various hazardous waste listing 
determinations and the dioxin emission rules for hazardous waste 
combustion units. Most of these assessments rely on several Agency 
guidance documents issued in recent years. In January 1990, the Agency 
issued an interim report, Methodology for Assessing Health Risks 
Associated with Indirect Exposure to Combustor Emissions (EPA/600/6-90/
003 and referred to as the Indirect Exposure Document). This document 
served as the basis for further development of non-groundwater pathway 
assessments by the Agency. In November 1993, the Agency issued an 
Addendum to the Indirect Exposure Document that updated and revised 
portions of the methodology presented in the Indirect Exposure 
document. In April 1994, OSW issued a draft implementation guidance 
entitled Implementation Guidance for Conducting Indirect Exposure 
Analysis at RCRA Combustion Units. In June 1994, the Agency released a 
review draft of Estimating Exposure to Dioxin-Like Compounds: Volumes 
I-III (EPA/600/6-88/005C), which presents an extensive and expanded 
version of the Agency's previous multiple pathway exposure assessments. 
Finally on November 16, 1994, the Agency issued Draft Soil Screening 
Guidance (59 FR 59225), which presents a multiple pathway assessment 
using air, groundwater, and soil pathways for soil screening levels at 
Superfund sites. The risk assessment presented relies on the 
methodologies presented in these Agency guidance documents to maintain 
consistency with previous Agency efforts.
    Based on these efforts by the Agency in conducting non-groundwater 
pathway assessments, comments by reviewers on previous draft versions 
of the risk assessment, and some screening analyses to identify 
pathways that are either very similar or unimportant compared to other 
pathways, the Agency selected the human and ecological exposure 
pathways presented in Table A-1 (human exposure pathways) of appendix A 
and Table A-2 (ecological exposure pathway) of appendix A. These 
exposure pathways are described in greater detail in the Technical 
Support Document for the Hazardous Waste Identification Rule: Risk 
Assessment for Human and Ecological Receptors.
    Tables A-1 and A-2 presents four columns: column 1 (exposure 
media), identifies the medium, such as air or soil, to which the 
receptor is exposed; column 2 (route of exposure), identifies the 
route, such as inhalation or ingestion, by which a receptor is exposed 
to the exposure medium; column 3 (type of fate and transport), 
classifies the pathway by the primary mode of fate and transport of the 
contaminant to the exposure medium, including direct air, air 
deposition, air diffusion, groundwater, overland, and soil; and column 
4 (exposure scenario), identifies the compartments in the pathway 
(e.g., source to air to humans), and describes the exposure scenario 
(e.g., inhalation of volatiles).
    The fate and transport pathways examined can be grouped into six 
types of initial release and movement away from a waste management 
unit, as follows:
     Direct air pathways--air emissions of volatiles and 
respirable (PM10) particulates;
     Air deposition pathways--air emissions of particulates 
that deposit on soil or plant surfaces;
     Air diffusion pathways--air emissions that, while in the 
vapor phase, diffuse directly into surface water or plants;
     Groundwater--groundwater releases (These are the pathways 
that link to the separate groundwater fate and transport analysis that 
then links to the waste management units.);
     Overland pathways--overland transport (i.e., surface 
runoff and soil erosion) to surface water or transport by soil erosion 
to off-site fields;
     Soil pathways--on-site soil exposures.
    There are three types of pathways not included in the analysis. 
Pathways involving the use of contaminated water (groundwater and 
surface water) for irrigation were removed due to modeling difficulties 
that could not be resolved, however early results indicated these are 
not the most significant pathways for any of the waste management 
units. Pathways involving the deposition of contaminated particles 
directly onto 

[[Page 66362]]
surface water bodies were not included because previous efforts by the 
Agency have shown these pathways not to be as significant when compared 
to particle deposition onto the watershed and subsequent erosion to the 
surface water body. Pathways involving wet deposition were not 
examined. An air model recently developed evaluates the impact of wet 
deposition and was not available to use at the time of this proposed 
rule. This new model also was addressing problems with the area 
component of earlier models. When the model is available, the Agency 
will determine whether its use will have an impact on the proposed exit 
criteria. If the Agency determines that there will be an impact, it 
will provide an opportunity for public comment on use of the updated 
model.
    As stated earlier, not all exposure pathways were evaluated for all 
waste management units. Constituents may be released from each waste 
management unit by a variety of mechanisms. Each release mechanism may 
be associated with certain exposure pathways. By examining the release 
mechanisms assumed for each waste management unit and identifying the 
exposure pathways associated with those release mechanisms, the 
appropriate pathways to be modeled for each waste management unit were 
identified. The exposure pathways modeled for each waste management 
unit are presented in Table A-5 of appendix A.
b. Equations
    Since the objective of the assessment was to generate acceptable 
levels in waste rather than determining risks posed by waste, the 
equations, which are designed to calculate risks, had to be turned 
around or run in reverse. The assessment began with a target risk (or 
acceptable risk to the receptor) that was used to back-calculate what 
constituent concentration in a waste would not exceed the target risk.
    Wherever appropriate, the equations used in the back-calculation 
were taken from Methodology for Assessing Health Risks Associated with 
Indirect Exposure to Combustor Emissions (U.S. EPA, 1990x; hereafter, 
the Indirect Exposure document, or IED) as modified by the November 10, 
1993, draft of Addendum: Methodology for Assessing Health Risks 
Associated with Indirect Exposure to Combustor Emissions, Working Group 
Recommendations (U.S. EPA, 1993x; hereafter, the Addendum). The 
Addendum is currently being revised based on comments from the Science 
Advisory Board and is being combined with the IED to generate a single 
methodology guidance document. Therefore, the equations may change 
after that revision is completed. If this occurs, the assessment used 
for this rule-making will be revised. If such a revision is needed and 
occurs, the Agency will provide an opportunity for public comment on 
those changes. For convenience, the methodology presented in the IED as 
modified by the Addendum will be referred to as the Indirect Exposure 
Methodology, or IEM.
    The equations presented in the IEM were modified to estimate the 
soil concentration for constituents eroding to an off-site field. The 
IEM did not address this pathway because it was developed for stack 
emissions from combustors rather than releases from land-based units. 
However, because soil erosion is a critical release pathway for this 
analysis, the Agency applied the Universal Soil Loss Equation (USLE) 
and other equations presented in the IEM to calculate soil erosion to 
the off-site field. However, the application of these equations 
resulted in concentrations greater at the receptor than in the waste 
management unit. This phenomenon, first noted in the Dioxin 
reassessment, occurred because the equations assumed that the amount of 
uncontaminated soil that was eroded into the field was negligible in 
comparison to the total mass of soil in the field. Therefore, the 
Agency modified these equations to reflect erosion of uncontaminated 
soil together with the constituents.
    Certain modifications to the equations used in the assessment were 
made for dioxin-like compounds to reflect the different behavior of 
these constituents in the environment. These modifications were based 
on Estimating Exposure to Dioxin-like Compounds, Volume III: Site-
Specific Assessment Procedures (U.S. EPA, 1994x), hereafter referred to 
as the Dioxin document. The Dioxin document defines dioxin-like 
compounds as ``* * * compounds with nonzero Toxicity Equivalency Factor 
(TEF) values as defined in the 1989 International scheme * * * [which] 
assigns nonzero values to all chlorinated dibenzodioxins (CDDs) and 
chlorinated dibenzofurans (CDFs) with chlorines substituted in the 
2,3,7,8 positions. Additionally, the analogous brominated compounds 
(BDDs and BDFs) and certain polychlorinated biphenyls (PCBs) have 
recently been identified as having dioxin-like toxicity * * * and thus 
are also included in the definition of dioxin-like compounds.''
    Although the modifications presented in the Dioxin document may be 
applicable to other highly lipophilic compounds, in keeping with this 
definition, the modifications for dioxin-like compounds were made only 
for 2,3,7,8-TCDDioxin Toxicity Equivalents (TEQs), and PCBs. Other 
dioxin congeners are addressed through the 2,3,7,8-TCDDioxin TEQ. The 
Agency solicits comment on not using these modifications for other 
highly lipophilic compounds.
(3) Specific Issues on Pathways and Equations
    Below are specific issues of the risk assessment related to the 
modeling of the fate and transport pathways on which the Agency is 
requesting comment on their use, improvements to them, or alternative 
ways to model them. A detailed discussion of these aspects is in 
Section 6, Fate and Transport Modeling, of the Technical Support 
Document for the Hazardous Waste Identification Rule: Risk Assessment 
for Human and Ecological Receptors. (Air emission and dispersion 
modeling is discussed in Section 7, Waste Management Units, in the 
technical support document. To be consistent, issues related to that 
modeling were presented earlier in this preamble in Section D.2.a.)
(i) Hydrolysis
    The Agency accounted for fate processes (e.g., biodegradation, 
hydrolysis) and transport processes (e.g., volatilization) for 
constituents throughout their movement from the point at which the 
constituent leaves the waste management unit until it reaches the 
location at which contact with the receptor occurs. During an initial 
screen, the Agency identified four constituents that were known to 
hydrolyze completely or rapidly. These constituents were not included 
in the detailed assessment and include: Benzotrichloride (98-07-7); 
maleic anhydride (108-31-6); phthalic anhydride (85-44-9); and 1,2-
diphenylhydrazine (122-66-7). In addition, 16 inorganic salts known to 
dissociate completely were also not assessed. These included: Calcium 
cyanide (592-01-8); copper cyanide (544-92-3); potassium cyanide (151-
50-8); potassium silver cyanide (506-61-6); silver cyanide (506-64-9); 
sodium cyanide (143-33-9); thallium (I) carbonate (6533-73-9); thallium 
(I) chloride (7791-12-0); thallium (I) nitrate (10102-45-1); thallium 
(I) sulfate (7446-18-6); zinc cyanide (557-21-1); zinc phosphide (1314-
84-7); cyanogen bromide (506-68-3); cyanogen chloride (506-77-4); 
hydrogen cyanide (74-90-8); and thallium acetate (563-68-8). The Agency 
solicits comment on not assessing these constituents. 

[[Page 66363]]

    Of the 192 constituents evaluated in the non-groundwater analysis, 
the Agency directly accounted for chemical hydrolysis for 18 
constituents. For the remaining constituents, hydrolysis was not 
considered for the following reasons: The constituent has no 
hydrolyzable chemical group; hydrolysis is not expected to be important 
or significant; the degradation half-life of the chemical, which 
includes hydrolysis, is greater than one year; or, there was no data 
available for the constituent.
    The extent to which fate and transport processes play a role in the 
removal of a constituent from a pathway, or its movement from one 
environmental compartment to another is determined by site-specific 
environmental conditions as well as chemical-specific parameters. To 
simplify the analysis, the Agency used fate and transport data based on 
one set of environmental conditions to represent all possible spatial 
and temporal environments encountered in any given exposure pathway. 
The Agency solicits comments on this simplification for modeling fate 
and transport processes throughout the exposure pathways considered in 
the MPA.
(ii) Other Fate and Transport Processes
    Fate and transport processes other than hydrolysis may be important 
in determining the concentration of a constituent reaching a receptor. 
The Agency's approach to incorporate consideration for these other 
processes involved the use of biodegradation and volatilization rates 
into the fate and transport pathways, when applicable. The Agency 
recognizes that the rate for many chemical-specific fate and transport 
processes (in particular, biodegradation) varies with characteristics 
of the environment (e.g., temperature, soil type). However, the Agency 
simplified the non-groundwater analysis by applying chemical-specific 
fate and transport rates generically across environmental settings 
found in the various exposure pathways. This simplification may 
overestimate the exit level in some instances and underestimate the 
exit level in other instances. The Agency solicits comments on this 
simplification for modeling fate and transport processes throughout the 
exposure pathways considered in the non-groundwater analysis.
(iii) Bioavailability
    With regard to the metals examined in the risk assessment, there is 
considerable uncertainty about their bioavailability that affects their 
fate, transport, and uptake in various media (e.g., plant tissue, 
animal tissue) and receptors. Speciation and associated solubility of 
metal species in wastes which contain metals are key factors that 
influence the bioavailability of metals. The Agency had no information 
on the speciation, solubility, or availability of the metals in the 
wastes in which they are disposed or how they may transform in the 
environment. The Agency assumed that the metals were in a soluble form, 
mobile, and available. In the absence of this information, the Agency 
assumed that metals are soluble, mobile, and bioavailable. The Agency 
seeks comment on this approach, and requests data on the speciation and 
solubility of metals in wastes, together with the conditions of the 
waste (e.g., pH) that could be disposed by the methods considered in 
this rulemaking and methodologies that account for the transformation 
of the metals through changing environmental conditions.
(iv) Meteorological Data
    The approach for setting central-tendency and high-end 
meteorological conditions in the risk assessment was to evaluate sets 
of meteorological data from a variety of locations, and then select 
locations that reflect central tendency or high-end conditions for a 
given exposure pathway.
    The Agency used the set of 29 meteorological stations identified 
during its efforts to develop soil screening levels for Superfund 
sites. These are considered representative of the United States. 
Central-tendency and high-end locations were then selected from these 
29 locations for the exposure pathways where meteorological conditions 
were required as input to the models; these were the air pathways and 
overland pathways. The meteorological data were evaluated as location 
sets as opposed to individual parameters. Once locations were selected, 
the annual average values for those locations were used.
    For air pathways, which required data on wind speed, wind 
direction, temperature, sunshine, cloud cover, and air mixing height, 
selection of meteorological data was waste management unit-specific and 
based on extensive sensitivity analysis. EPA considered only the effect 
of meteorological data on emissions and dispersion in selecting 
locations for air pathways. However, for consistency, once a pair of 
high-end and central tendency locations were selected for a pathway, 
any meteorological data used in that pathway were selected to 
correspond to the locations chosen, even in any overland transport 
component of the pathway.
    Overland pathways were driven by soil erosion, for which the 
critical meteorological input is the Universal Soil Loss Equation 
(USLE) rainfall factor (R). Therefore, to select central tendency and 
high-end locations for overland pathways, the 29 locations were ranked 
based on the rainfall factor, and the 50th and 90th percentile 
locations chosen for all overland pathways.
    See Section 6.8, Fate and Transport Inputs and Section 7.1.5. Air 
Modeling, of the Technical Support Document for the Hazardous waste 
Identification Rule: Risk Assessment for Human and Ecological Receptors 
for a detailed discussion of how meteorological data were selected and 
used. The Agency solicits comment on how meteorological data was 
selected and used in the risk assessment.
(v) Soil Data
    A variety of soil parameters were required for the modeling. These 
parameters are interdependent and vary with the type of soil (e.g., 
loam, clay). However, values for these parameters also vary within a 
soil type. Due to the interdependence of the parameter, the Agency 
chose to maintain them as a set and determine a central-tendency 
property set and a high-end property set.
    The Agency used loam type soils to characterize all soils simulated 
in the risk assessment because these types of soils are fairly 
prevalent in the United States. All soils are composed of varying 
percentages of sand, silt, and clay. Loam, by definition, is composed 
of equal proportions of sand, silt, and clay; therefore, it represents 
a combination of each of the physical properties of the individual soil 
textures. Central tendency and high-end values were selected from the 
range of values for loam soil so that each individual soil parameter 
required by the model is consistent with a loam soil. (Sec Section 6.8, 
Fate and Transport Inputs, in the Technical Support Document for the 
Hazardous Waste Identification Rule: Risk Assessment for Human and 
Ecological Receptors for more detail.) The Agency solicits comments its 
approach for characterizing soil in the assessment.
(vi) Soil Pathways
    The Agency seeks comment on the following issues related to the 
modeling of soil pathways:
     Use of the Universal Soil Loss Equation to predict soil 
erosion in a generic application - This is a widely-used model intended 
for site-specific 

[[Page 66364]]
applications where specific input data can be used for relatively small 
fields. Its use in a generic application, and for fairly large waste 
management units, may overestimate quantities of soil eroded.
     Handling of the Soil Loss Constant - This term is the sum 
of loss rates for leaching, erosion, runoff, biodegradation, 
hydrolysis, and volatilization. Possible uncertainties may arise 
because: the assessment assumes that these terms are first-order decay 
rates and therefore can be added together; loss processes are 
calculated independently, even though they may occur simultaneously.
     Use of the Soil Water Content Equation to predict soil 
water content in a generic application - The equation is from the 
Superfund Exposure Assessment Manual (U.S. EPA, 1988x), and was 
developed for site-specific applications.
     Area of garden and agricultural field - No data were 
available on the size of home gardens, gardens on subsistence farms, or 
yards of residential lots (for soil ingestion). Therefore, a single set 
of central tendency and high-end values was estimated for these, based 
on best professional judgment; this set is referred to as garden area, 
even though it might also apply to a yard. Because a larger area leads 
to greater dilution of deposited or eroded contaminant, a high-end 
garden would be one that was relatively small.
     Areas for agricultural fields were estimated from data in 
the 1992 Census of Agriculture (U.S. Department of Commerce, 1992). The 
Census gives average farm acreage by State for 48 States (the data are 
not yet complete for the two missing States). No percentile data were 
available. These data do not distinguish between commercial and 
subsistence farms.
     Mixing Depth--Mixing depth reflects the depth of soil to 
which deposited or eroded contaminant is mixed. It is important to 
distinguish between soil that is tilled for agricultural purposes and 
soil that is untilled in determining appropriate mixing depth values. A 
smaller mixing depth results in less dilution of a constituent, and 
therefore higher soil concentrations; therefore, a high-end mixing 
depth would be smaller than a central tendency mixing depth.
(vii) Surface Water Pathways
    Water column as well as benthic sediment concentrations were 
estimated. Water column concentrations include dissolved, sorbed to 
suspended sediments, and total (sorbed plus dissolved, or total 
contaminant divided by total water volume). Benthic sediment 
concentrations included: Dissolved in pore water, sorbed to benthic 
sediments, and total. The model accounts for three routes of 
constituent entry into the water-body were examined: Sorbed to soils 
eroding into the water-body; dissolved in runoff water; and diffusion 
of vapor phase contaminants into the water-body. Air deposition of 
constituents bound to particles into a water-body was not examined 
because earlier analysis demonstrated that its contribution would be 
negligible when compared to that of eroding particles. Volatilization 
of dissolved constituents and removal of constituents through burial in 
bed sediments were modeled as loss processes.
    Important assumptions made for the surface water modeling included: 
Water-body sufficiently large to support certain ecological receptors; 
sufficient fish to support a subsistence fisher; uniform mixing within 
the water-body (this tends to be more realistic for smaller water-
bodies as compared to large river systems); and equilibrium is 
established between constituents within the water column, bed 
sediments, and air.
    The Agency seeks comment on the following issues related to the 
modeling of surface water pathways:
     Water-body/Watershed Characterization--The water-body 
characterization parameters are another example of a set of parameters 
that are interdependent and therefore were used as a group. Watershed 
characterization relates to the water-body (in the case of the 
assessment, a stream) characterization. Streams are characterized 
(flow, water-body area, watershed area, depth, and various other 
parameters) by their ``order.'' A first-order stream has no tributary 
channels; a second-order stream forms when two first-order streams 
converge, and so on through stream order 10. The Agency used a stream 
order 4 as the high-end estimate because EPA believes this stream order 
would be among the smallest stream orders that would support sufficient 
fish or a subsistence fisher and the receptors assessed. A stream order 
5 was used as the central-tendency estimate based on the number of 
streams within each stream order. (See Section 6.8 in the Technical 
Support Document for the Hazardous Waste Identification Rule: Risk 
Assessment for Human and Ecological Receptors for more detail.)
     Total Suspended Solids--Total suspended solids (TSS) can 
range from 1 to 100 mg/L with a typical value being 10 mg/L for streams 
and rivers. This value is used as the central tendency value. No data 
on frequency of values in actual streams was available to estimate a 
90th percentile value. Since 80 mg/L is believed to be the maximum 
tolerable value for aquatic life; this value was used as the high-end 
value.
     Bed Sediment Concentration--The bed sediment concentration 
term is analogous to the bulk density for soil in that it describes the 
concentration of solids in terms of a mass per unit volume. A single 
value of 1 kg/L was used in the assessment given that this is 
considered a reasonable value in most situations and the range is quite 
narrow, 0.5 to 1.5 kg/L.
     Gas-Phase Transfer Coefficient--The gas-phase transfer 
coefficient is used to estimate volatile losses from the water-body. 
Volatile losses are calculated using a two-layer resistance model that 
incorporates a gas-phase transfer coefficient and a liquid-phase 
transfer coefficient. Both transfer coefficients are controlled by flow 
induced turbulence in flowing systems. The liquid-phase transfer 
coefficient is calculated based on chemical-specific properties. A 
single value of 36,500 m/yr. was used. There is some uncertainty 
related to setting this parameter to a single value that is not 
chemical specific. It is reasonable to assume that chemical properties 
affecting volatility would have some effect on this value, although it 
is not known how large such an effect would be.
     Fraction Organic Carbon in Bottom Sediment--The fraction 
organic carbon in bottom sediment is derived from the fraction organic 
carbon in watershed soils. For a fraction organic carbon of about 0.01 
in the watershed, the fraction organic carbon for bottom sediments is 
typically 0.03 to 0.05. The midpoint of this range, 0.04, divided by 
the fraction organic carbon of the watershed (0.01) derives a 
multiplier of 4 for calculating fraction organic carbon in bottom 
sediments from fraction organic carbon in watershed soils. The fraction 
organic carbon values used of 0.024 and 0.008 correspond to the central 
tendency and high-end values for soil fraction organic carbon of 0.006 
and 0.002, respectively. The fraction organic carbon in the bottom 
sediments was varied with the fraction organic carbon in soil.
(viii) Food-Chain Pathways
    The Agency seeks comment on the following issues related to the 
modeling of food-chain pathways: (Please note the fish uptake 
methodology is described below in Section D.2.c.2), Ecological 
Receptors and Exposure; the littoral methodology is used for humans): 

[[Page 66365]]

     Use of regression equations based on Kow to derive 
biotransfer factors for plants--The biotransfer factors are based upon 
empirical relationships with Kow defined by studies on relatively few 
chemicals.
     The lack of accounting for translocation of contaminants 
within plants--The plant uptake models do not account for translocation 
of contaminants (should such a translocation occur) from one part of a 
plant to another. The Agency is considering two models developed by 
Stephan Trapp, plantx and plantE, and solicits comment on their use.
     Use of regression equations based on Kow to derive 
biotransfer factors for beef and milk--The biotransfer factors for beef 
and milk are based upon empirical relationships with Kow defined by 
studies on relatively few chemicals.
c. Receptors
    Both human and ecological receptors are considered in the 
assessment. The human receptors evaluated were selected to represent a 
range of behaviors and activities that influence exposure levels. The 
Agency believes that these represent typical and more exposed types of 
behaviors and activities that might exist around waste management units 
or media contaminated by releases from waste management units. Each 
receptor was evaluated for individual exposure pathways (i.e., exposure 
to multiple pathways was not included). For ecological receptors, 
populations or communities were selected for the generic terrestrial 
and freshwater ecosystems based on behavior patterns such as dietary 
habits (plant-eater vs. meat-eater) as well as qualities such as 
significance and representativeness with respect to trophic structure 
in the ecosystem (bald eagle). The selection of ecological receptors 
was limited by the level of characterization available such as food 
intake and body weight. Again, the Agency believes that these represent 
the types of organisms that might exist around waste management units 
or media contaminated by releases from waste management units.
(1) Human Receptors and Exposure
    Human receptors assessed in the assessment included the following:
     Adult resident living in the vicinity of a management 
unit--This individual is representative of the general population in 
the United States and is evaluated independently through the following 
potential exposure pathways: Inhalation, ingestion of contaminated 
soil, ingestion of contaminated drinking water, dermal contact with 
contaminated soil, and dermal contact during bathing. In addition, the 
analysis evaluates exposures to an adult resident living on-site of a 
land application unit begining 10 years after closure of the unit.
     Child resident living in the vicinity of a management 
unit--Children are a special population considered in certain pathways 
because of their low body weight compared to high intake rates or 
surface area. A child is evaluated through the following potential 
exposure pathways: ingestion of contaminated soil, dermal contact with 
contaminated soil, and dermal contact during bathing.
     Home Gardener--This individual represents a sub-population 
that supplements their fruit and vegetable consumption with fruits and 
vegetables they grow on contaminated land.
     Subsistence Fisher--This individual represents a sub-
population that subsists on contaminated fish.
     General Fish Consumer--This individual represents a sub-
population that consumes contaminated fish and supplements their intake 
with other non-contaminated foods.
     Subsistence Farmer--This individual represents a sub-
population that grows or raises most of their own food on contaminated 
land. This individual is evaluated independently through the following 
exposure pathways: beef ingestion, milk ingestion, and fruit and 
vegetable ingestion.
     On-site Worker--This individual represents the working 
population that may be found at the waste management units. This 
individual is evaluated during the active phase of the unit for the 
following on-site exposures: Inhalation and dermal contact with 
contaminated soil.
    Each of the receptors has been matched with the most relevant 
exposure routes. Table A-3 in appendix A shows the pathways were 
modeled for each receptor.
    As previously discussed, the assessment begins with a target human 
toxicity benchmark and exposure assumptions tailored to each receptor, 
and back-calculates to constituent-specific concentrations in each 
media. In characterizing the exposure, two exposure parameters are set 
to high-end values and the rest of the exposure parameters are set to 
central tendency or default values. The two high-end exposure values 
were typically exposure duration and a parameter affecting intake of, 
or exposure to, a contaminant (e.g., fraction contaminated, consumption 
rate, inhalation rate).
    The exposure equations used for back-calculating media 
concentrations are based on standard risk equations used in most Agency 
risk assessments. For all inhalation and ingestion pathways, these 
equations were adapted from Risk Assessment Guidance for Superfund 
(RAGS): Volume I--Human Health Evaluation Manual (Part B, Development 
of Risk-based Preliminary Remediation Goals) (U.S. EPA, 1991x; 
hereafter, RAGS Part B) and subsequent modifications. For dermal 
pathways, which are not covered in RAGS Part B, the equations presented 
in Dermal Exposure Assessment: Principles and Applications, Interim 
Report (U.S. EPA 1992x; hereafter, the Dermal document) were used; this 
document reflects the current techniques for assessing dermal exposure. 
The Agency requests comment on the data sources and assumptions used in 
the human exposure portion of the risk assessment, described in detail 
in Section 5.0 of the Technical Support Document for the Hazardous 
Waste Identification Rule: Risk Assessment for Human and Ecological 
Receptors.
    The Agency seeks comment on the following types of human exposure 
that were not examined:
     Ingestion of contaminated water by humans while bathing or 
swimming--The ingestion rate of water while swimming or bathing is 30 
times smaller than the normal consumption rate of water used in the 
drinking water ingestion pathways; therefore, the drinking water 
ingestion pathways should be protective of the incidental water 
ingestion pathways.
     Inhalation of volatiles while bathing--No appropriate, 
chemical-specific equations could be found to address this pathway.
     Ingestion of airborne particulates--The ingestion rate of 
soil used in the soil ingestion pathways is many times larger than the 
ingestion rate from airborne particulates; therefore, the soil 
ingestion pathways should be protective of the ingestion of airborne 
particulates. Also, given the way the soil ingestion rates were 
empirically derived, ingestion of airborne particulates should, in 
effect, be accounted for in the estimated soil ingestion rates.
     Ingestion of contaminated soil by resident on active 
site--While the waste management units are active, it is assumed that 
access is limited to workers.
(2) Ecological Receptors and Exposure
    In addition to the human receptors, ecological receptors were 
evaluated in the assessment. Lacking an Agency precedent for the 
selection of ecological 

[[Page 66366]]
receptors for a generic analysis, a simple framework was developed for 
ecological receptor identification based on EPA's Framework for 
Ecological Risk Assessment (U.S. EPA, 1992x). During the problem 
formulation phase, a suite of ecological receptors was selected to 
include species that represent each of the trophic levels or feeding 
habits within an ecosystem. At best, one can only infer that an 
ecosystem is protected from chemical stressors. In addition, the 
toxicological data support the evaluation of individuals, populations, 
and occasionally communities, but are inadequate to address the 
complexities of an ecosystem in most cases. Thus, the approach taken in 
the assessment was to estimate protective levels for the populations 
and communities (inferred from the measurement endpoints used) found in 
generic ecosystems. The species included in the ecological assessment 
encompass a wide range of dietary preferences, sizes, and trophic 
levels.
    In selecting ecological receptors for the assessment, a number of 
ecosystem types (e.g., lakes, streams, estuaries, deserts, forests, 
grasslands) were considered because the waste could be disposed 
anywhere once it has exited the Subtitle C system. Two generic 
ecosystems were designed: A freshwater-based ecosystem and a 
terrestrial-based ecosystem. Specific details of these ecosystems are 
described in Section 3, Receptors, in the Technical Support Document 
for the Hazardous Waste Identification Rule: Risk Assessment of Human 
and Ecological Receptors. The Agency solicits comment on both the 
adequacy of the design of the ecosystems used in the assessment and the 
use of generic ecosystems to assess potential ecological hazards.
    Generally, ecological receptors were identified at different 
trophic levels as well as at different levels of biological 
organization and included species of relatively low ecological 
significance but high societal relevance (e.g., American kestrel). The 
final selection of receptors was based primarily on the availability of 
data with which to assess the risks to that receptor. As suggested in 
the Framework for Ecological Risk Assessment (1992x), the process of 
selecting appropriate assessment endpoints was iterative, including 
information from the other activities included in the assessment 
phase--the characterization of ecological effects. The ecological 
receptors included in the assessment were:
     Mammals--Mammals were evaluated for both generic 
ecosystems and include upper trophic level predators such as the mink 
or red fox, lower trophic level consumers such as the whitetail deer, 
and insectivores such as the meadow mole; species were selected to 
represent a variety of body sizes, habitats, and dietary habits for 
which data on body weight, food intake, etc., are available. Mammals 
may be exposed by eating contaminated prey items (e.g., fish, other 
vertebrates, insects) or plants, through incidental ingestion of 
contaminated soil while eating or preening, or through lactation or 
placental transfer.
     Birds--Birds were also evaluated for both generic 
ecosystems and include upper trophic level predators such as the red-
tailed hawk and lower trophic level consumers such as the American 
robin; species were selected to represent a variety of body sizes, 
habitats, and dietary preferences for which input parameters (e.g., 
body weight, diet, ingestion rates) are available. Birds are exposed 
through the ingestion of contaminated prey items (e.g., fish, worms), 
through incidental ingestion that occurs while eating or preening, or 
through maternal transfer to eggs.
     Terrestrial Plants--Vascular plants that might be common 
in a generic terrestrial ecosystem were evaluated. The species of 
plants used to represent plants within the terrestrial ecosystem were 
determined by the availability of data and included primarily forage 
grasses and food crops. Plants are exposed through soil-to-root uptake, 
deposition on the surface of leaves or bark, and during air-to-leaf 
transport of volatile or semi-volatile constituents.
     Soil Community--Representative species for the soil 
community were based on six metrics for measuring ecological function: 
(1) Location, (2) size, (3) abundance, (4) taxon richness, (5) trophic 
structure, and (6) energy metabolism. Organisms living in or on the 
soil are exposed through direct contact (e.g., insects), through the 
ingestion of contaminated soil (e.g., earthworms), and through the 
ingestion of other soil dwellers (e.g., centipedes). The Agency 
solicits comment on the representative species selected to comprise the 
soil community.
     Fish--Given the small percentage of freshwater species for 
which toxicological data are available, all species of freshwater fish 
were considered as potential receptors, regardless of size or dietary 
habits. Fish are subject to continuous exposure to contaminated water 
via gill exchange and may be exposed to bioaccumulative chemicals 
through the food chain.
     Aquatic Invertebrates (Daphnids)--Aquatic invertebrates 
are believed to be among the most sensitive aquatic species (Suter, 
1993x), daphnids were selected to represent free living aquatic 
invertebrates. Continuous exposure to contaminated water is considered 
the primary route of exposure.
     Aquatic Plants--Vascular aquatic plants and algae typical 
of aquatic ecosystems were evaluated. Aquatic plants are exposed during 
sediment-to-root uptake and through water-to-leaf transport.
     Benthic Community--Representative species include 
organisms that fall within any of the eight taxonomic genera used in 
the development of the Ambient Water Quality Criteria for the 
protection of aquatic life. Because these organisms spend most (if not 
all) of their lives in the sediment, they are exposed through direct 
contact and ingestion of contaminated sediments as well as through the 
ingestion of other sediment dwellers.
    Each of these receptors has been matched with the exposure pathways 
and waste management units likely to result in exposure. Table A-4 of 
appendix A shows which pathways were modeled for each receptor. The 
Agency solicits comment on the use of a single species to represent 
major trophic elements.
    The development of medium-specific concentrations for the 
protection of ecological receptors was based on ingestion of 
contaminated vegetation, water, soil, or prey or through continual 
contact with a contaminated medium (e.g., aquatic invertebrates with 
water or soil fauna with soil).
    Numerous studies have demonstrated the capacity of hydrophobic 
organic chemicals to bioaccumulate in the food chain that are orders of 
magnitude above the concentration in the contaminated medium (e.g., 
Oliver and Niimi, 1988x). However, it is important to recognize that 
food-chain pathways may be significant even for constituents that do 
not bioaccumulate appreciably. Dietary exposure to constituents that 
concentrate weakly in fish tissue (e.g., bioconcentration factor below 
10) may be more significant than exposure to contaminated drinking 
water simply because a particular animal may ingest relatively more 
fish than water.
    For constituents that bioaccumulate, particularly those that 
biomagnify, benchmarks should account for exposure through the 
ingestion of contaminated prey as well as contact with or ingestion of 
contaminated media. The majority of toxicological studies examined a 
single route of exposure and seldom considered the potential increase 
in exposure concentrations through successive 

[[Page 66367]]
trophic levels. As a result, toxicity benchmarks for bioaccumulative 
constituents cannot be used as acceptable medium exposure 
concentrations; exposure estimates must incorporate the bioaccumulation 
potential in the food chain. For nonbioaccumulating constituents, where 
toxicity benchmarks that are medium specific (i.e., concentration 
units--mg/kg or mg/L)) can be used as acceptable medium concentrations 
for ecological receptors (e.g., Ambient Water Quality Criteria).
    In the aquatic ecosystem, for bioaccumulative chemicals (log 
Kow>4), bioaccumulation factors (BAFs) were estimated using models 
developed by Thomann (1989x) for the limnetic (or pelagic) food chain 
and Thomann et al. (1992x) for the littoral food chain (i.e., sediment-
based). However, for constituents with log Kow above 6.5, only 
measured values were used. The Agency is considering using the Gobas 
model since it can be used for constituents with log Kow above 
6.5. Further, switching to the Gobas model would be consistent with the 
Great Lakes Initiative which recently switched to that model. The 
results produced by either the Thomann models or the Gobas model are 
very similar. The tissue concentration (TC) was estimated for prey 
based on the intake, body weight, and dietary preference (i.e., trophic 
level of fish consumed) of the representative predator species. 
Protective surface water concentration was calculated by dividing the 
tissue concentration (TC) by the bioaccumulation factor for the 
appropriate trophic level. For nonbioaccumulative chemicals, the 
protective surface water concentration for fish and aquatic organisms 
was the Final Chronic Value (FCV) or Secondary Chronic Value (SCV) as 
described in Section 4 of the Technical Support Document for the 
Hazardous Waste Identification Rule: Risk Assessment for Human and 
Ecological Receptors. For upper trophic level aquatic wildlife such as 
mink and osprey, protective surface water concentrations were 
calculated based on the consumption of contaminated fish and water. The 
benthic community was included in the littoral ecosystem. Protective 
sediment concentrations were estimated using the equilibrium 
partitioning (Eqp) methods developed by Di Toro et al. (1991x). As 
explained in Section 4 of the Technical Support Document for the 
Hazardous Waste Identification Rule: Risk Assessment for Human and 
Ecological Receptors, the sediment benchmark was calculated by 
multiplying the FCV (or SCV) by the octanol/carbon partition 
coefficient (Koc) and adjusting for the fraction organic carbon 
(foc) in the sediment. EPA requests comment on the selection of 
the bioaccumulation model, the potential switch to the Gobas model, 
BAFs used, dietary assumptions, and how tissue concentrations were 
calculated.
    For receptors in the generic terrestrial ecosystem, methods used 
represented a range of dietary habits across trophic levels for 
wildlife, including plants and organisms that live in the soil (i.e., 
soil fauna). (See the discussion on the development of soil and plant 
benchmarks elsewhere in today's rule.) For higher trophic level 
wildlife, dietary preferences, daily intake, and bioconcentration 
factors for prey items were identified or estimated to calculate 
protective soil concentrations. The key equation used to back-calculate 
soil concentrations as a function of dietary exposure (including soil 
ingestion), and the exposure inputs (e.g., body weights, daily intake) 
for ecological receptors are discussed in Section 5.3 of the Risk 
Assessment. The Agency requests comment on the equations and inputs 
used in the generic terrestrial ecosystem modeling.
    The following types of exposure were not assessed in the 
assessment:
     Inhalation by ecological receptors--No suitable 
methodology was available.
     Dermal contact with soil--No suitable methodology or 
sufficient toxicity data were available.
     Dermal contact with water--No suitable methodology or 
sufficient toxicity data were available.
3. Groundwater Fate and Transport Modeling
    In the risk analysis previously described in the section, the 
pathways involving groundwater are only modeled (back-calculated) to 
the wellhead, i.e., to the point of exposure at a water well. For 
groundwater modeling from the waste management unit (i.e., surface 
impoundment) to the water well, the Agency used a separate fate and 
transport analysis. This section describes the groundwater model and 
the modeling procedures for the various waste management scenarios for 
the groundwater path. The details of the model and the modeling 
procedures are presented in the background documents (USEPA, 1995 a-f).
    The Agency has developed specialized subsurface fate and transport 
modeling for four waste management options: (1) Landfills; (2) surface 
impoundments; (3) waste piles; and (4) land application units. All four 
waste management scenarios assume that the waste if exempted could be 
managed in the respective RCRA Subtitle D units. In deriving the 
exemption levels, the Agency needs to evaluate the fate and transport 
of constituents from the waste unit to the nearby drinking water wells. 
The potential migration of constituents from a waste unit to the 
leachate at the bottom of the waste unit can be simulated by the 
laboratory test, the Toxicity Leaching Procedure (TCLP), or the 
Synthetic Precipitation Leaching Procedure (SPLP), Method 1312. 
Although one procedure may be more applicable for some wastes than the 
other procedure, as described on page 21483 of the Federal Register 
Notice of May 20, 1992 (57 FR 21450), the Agency is soliciting comments 
on the applicability and use of one test over the other for this 
proposal.
    The fate and transport of constituents in leachate from the bottom 
of the waste unit through the unsaturated zone and to a drinking water 
well in the saturated zone is estimated using a fate and transport 
model. The Agency proposes to use EPACMTP (EPA's Composite Model for 
leachate migration with Transformation Products) for this purpose. The 
EPACMTP considers not only the subsurface fate and transport of 
chemical constituents, but also the formation and the fate and 
transport of transformation (daughter) products. The Agency also 
solicits comments on the technical correctness and applicability of the 
model and the data for this proposal.
    The Agency proposed the use of a subsurface fate and transport 
model (EPASMOD) on June 13,1986 (51 FR 21648) in the Toxicity 
Characteristic (TC) Rule. However, after receiving numerous comments, 
the Agency revised the model and the data used in the model (53 FR 
28692) and the enhanced model (EPACML) was used in the TC Final Rule 
(55 FR 11798). The EPACMTP replaces the EPACML for use in this 
proposal. The EPACMTP was recently published in a refereed journal 
(Kool, Sudicky and Saleem, Journal of Contaminant Hydrology 17(1994) 
69-90) and has been reviewed by the EPA's Science Advisory Board (SAB). 
The SAB commended the Agency for making for its significant 
improvements to the model. They also stated that it represents the 
state of the art for such analyses. However, they also recommended 
additional testing of the model.
    The modeling approach used for this proposed rulemaking includes 
three major categories of enhancements over the EPACML and the approach 
for the TC rule. The enhancements fall into the 

[[Page 66368]]
following categories: (1) Incorporation of additional fate and 
transport processes (e.g., degradation of chemical constituents); (2) 
Use of enhanced flow and transport solution algorithms and techniques 
(e.g., three-dimensional transport); and (3) Revision of the Monte 
Carlo methodology (e.g., site-based implementation of available input 
data). A discussion of the key enhancements which have been implemented 
in the EPACMTP is presented here and the details are provided in the 
background documents (USEPA, 1995a-g). The Agency is soliciting 
comments on the modeling enhancements and the modeling methodology as 
well as on the values derived for individual chemical constituents:
(1) Fate and Transport Processes
    Effects of groundwater mounding underneath waste unit.--The EPACML 
was limited to conditions of uniform groundwater flow. It could not 
handle accurately the conditions of significant groundwater mounding 
and non-uniform groundwater flow due to a high rate of infiltration 
from the waste units. These conditions increase the transverse 
horizontal as well as the vertical spreading of a contaminant plume. 
The EPACMTP accounts for these effects directly by simulating 
groundwater flow in the vertical as well as horizontal directions 
(USEPA, 1995 a).
    Transformation products.--The EPACMTP model has capability to 
simulate the formation and fate of multiple transformation products (up 
to seven) in the unsaturated as well as in the saturated zones. For 
constituents which have toxic transformation products, the EPACMTP can 
provide an assessment of the groundwater impact of the transformation 
products, along with that of the parent constituent. This methodology 
has been implemented for hydrolyzing organic constituents included in 
this proposal.
    Fate and transport of metals.--The EPACMTP can simulate fate and 
transport of metals, taking into account geochemical influences on the 
mobility of metals. The EPA's MINTEQA2 (USEPA, 1995 f) metals 
speciation model is used to generate effective sorption isotherms for 
individual metals, corresponding to a range of geochemical conditions. 
The transport modules in EPACMTP have been enhanced to incorporate the 
nonlinear MINTEQ sorption isotherms. This enhancement provides the 
model with capability to simulate, in the unsaturated and in the 
saturated zones, the impact of Ph, leachate organic matter, natural 
organic matter, iron hydroxide and the presence of other ions in the 
groundwater on the mobility of metals.
(2) Enhanced Solution Algorithms and Techniques
    Linkage between unsaturated zone and saturated zone modules.--The 
saturated zone module implemented in the EPACML was based on a Gaussian 
distribution of concentration of a chemical constituent in the 
saturated zone. The module also used an approximation to account for 
the initial mixing of the contaminant entering at the water table 
underneath the waste unit. The approximate nature of this mixing factor 
could sometimes lead to unrealistic values of contaminant concentration 
in the groundwater close to the waste unit, especially in cases of a 
high infiltration rate from the waste unit. The enhanced model 
incorporates a direct linkage between the unsaturated zone and 
saturated zone modules which overcomes these limitations of the EPACML.
    Numerical transport solution modules.--To enable a greater 
flexibility and range of conditions that can be modeled, the analytical 
saturated zone transport module has been replaced with a numerical 
module, based on the highly efficient state-of-the-art Laplace 
Transform Galerkin (LTG) technique. The enhanced module can simulate 
the anisotropic, non-uniform groundwater flow, and transient, finite 
source, conditions. The latter requires the model to calculate a 
maximum receptor well concentration over a finite time horizon, rather 
than just the steady state concentration which was calculated by the 
EPACML. The saturated zone modules have been implemented to provide 
either a fully three-dimensional solution, or a highly efficient quasi-
3D solution. The latter has been implemented for Monte Carlo 
applications and provides nearly the same accuracy as the fully three-
dimensional option, but is more computationally efficient. Both the 
unsaturated zone and the saturated zone transport modules can 
accommodate the formation and the transport of parent as well as of the 
transformation products.
    Solution for nonlinear metals transport.--A highly efficient semi-
analytical unsaturated zone transport module has been incorporated to 
handle the transport of metals in the unsaturated zone and can use 
MINTEQA2 derived linear or nonlinear sorption isotherms. Conventional 
numerical solution techniques are inadequate to handle extremely 
nonlinear isotherms. An enhanced method-of-characteristic based 
solution has been implemented which overcomes these problems and 
thereby enables the simulation of metals transport in the Monte Carlo 
framework. Non-linearity in the metals sorption isotherms is primarily 
of concern at higher concentration values; for low concentrations, the 
isotherms are linear or close to linear. Because of the attenuation in 
the unsaturated zone, and the subsequent dilution in the saturated 
zone, concentrations in the saturated zone are usually low enough so 
that properly linearized isotherms are used by the model in the 
saturated zone without significant errors.
    Elimination of biases in determination of receptor well location.--
The internal routines in the model which determine placement of the 
receptor well relative to the areal extent of the contaminant plume 
have been revised and enhanced to eliminate bias which was present in 
the implementation in the EPACML. The calculation of the areal extent 
of the plume has been revised to take into consideration the dimensions 
of the waste unit. The logic for placing a receptor well inside the 
plume limits has been improved to eliminate a bias towards larger waste 
unit areas and to ensure that the placement of the well inside these 
limits, for a given radial distance from the unit, is truly randomly 
uniform. However, for this proposal, the closest drinking water well is 
located anywhere on the downgradient side of the waste unit and the 
Agency is soliciting any comments on this procedure.
(3) Revisions of Monte Carlo methodology for nationwide assessment
    Data sources.--The data sources from which parameter distributions 
for nationwide Monte Carlo assessments are obtained have been 
evaluated, and where appropriate, have been revised to make use of the 
latest data available for modeling. Leachate rates for Subtitle D waste 
units have been revised using the latest version of the HELP model with 
the revised data inputs. Source specific input parameters (e.g., waste 
unit area and volume) have been developed for various different types 
of industrial waste units besides landfills. Input values for the 
groundwater related parameters have been revised to utilize information 
from a nationwide industry survey of actual contaminated sites.
    Finite-source methodology.--The original version of the model was 
implemented for Monte Carlo assessments assuming continuous source 
(infinite source) conditions only. This methodology did not take into 
account the finite volume and/or operational life of waste units. The 
EPACMTP model has been 

[[Page 66369]]
implemented for Monte Carlo assessments of either continuous source or 
finite source scenarios. In the latter scenario, predicted groundwater 
impact is not only based on the concentrations of contaminants in the 
leachate, but also on the amount of constituent in the waste unit and/
or the operational life of the unit. The Monte Carlo methodology was 
enhanced to allow determination of regulatory threshold levels for 
these two waste characteristics USEPA, 1995.
    Site-based regional analysis.--The Monte Carlo methodology has been 
fundamentally revised and enhanced to account for the interdependency 
among the various model input parameters based on regional 
distributions. The original methodology simply assumed that a waste 
site could be located anywhere in the US, and that the probability 
distributions of individual model parameters (e.g., infiltration rate, 
depth to groundwater, etc.) at any waste site were mutually independent 
and given by their nationwide frequency distributions. The model 
therefore only had limited capability to account for correlations and 
dependencies among the model parameters. To address this limitation, a 
site-based methodology has been implemented, based on the OSW's surveys 
of existing waste facilities in the US, and their geographical 
locations. The information of geographical location is used in this 
enhanced approach to select the other model parameters, such as 
infiltration rate and hydrogeological characteristics. A number of 
different sources were reviewed for the development of the site-based 
approach. Four of these sets were selected to derive the regional 
characteristics of the more important parameters for each sampled site: 
The OSW's survey of industrial waste management units (EPA, 1986); the 
infiltration and recharge analysis performed for U.S. climatic regions; 
the U.S. Geological Survey inventory of groundwater resources; and the 
API's (American Petroleum Institute) survey of hydrogeologic parameters 
for the different groundwater environments in the U.S.
(4) Implementation of EPACMTP
    The specific modeling options selected for the modeling analyses 
are summarized in Table 3 below. All modeling analyses were conducted 
in the finite source, Monte Carlo mode, for four industrial Subtitle D 
waste management scenarios. The groundwater fate and transport model 
was used to predict the maximum concentration at a receptor well placed 
down gradient from the waste unit. A 10,000 years time limit was 
imposed on the exposure time period, i.e., the calculated concentration 
is the highest exposure concentration occurring within 10,000 years 
following the initial release from the waste unit. The Monte Carlo fate 
and transport simulation provides a probability distribution of 
receptor well exposure concentrations as a function of waste and 
leachate concentrations. For this proposal, the groundwater modeling 
results were used to derive leachate concentration thresholds. For 
carcinogenic constituents, the exposure concentration calculated by the 
model corresponds to the maximum 30-year average receptor well 
concentration. For non-carcinogenic constituents, the peak receptor 
well concentration is used. The regulatory threshold leachate 
concentration limits were determined using a back-calculation 
procedure, to correspond to an approximate 90th percentile protection 
level. This means that the closest downgradient drinking-water wells at 
90% of the industrial Subtitle D waste management units would have 
water concentrations below the HBN/MCL. The wells further away at 90% 
of the sites would be protected at higher protection levels. The wells 
at the other 10% of the sites would be protected at lower protection 
levels.
    The Agency uses a 95th percentile protection level in the RCRA 
Delisting program and the 85th percentile for the toxicity 
characteristic program. These two programs have slightly different 
goals from the exemption proposed today. The recently developed 
Superfund soil-screening levels use a 90th percentile protection level 
to identify sites at which no additional investigation for possible 
remediation is required. The exit proposed today is similar to the 
soil-screening levels program. Today's proposed exit is intended to 
identify wastes no longer needing Subtitle C management. Finally, the 
90th percentile was chosen because it is nearly consistent with the 
protectiveness level in the other pathways of the multipath risk 
assessment performed for today's proposal as far as could be 
identified.
    Table 3 provides a summary of the methodology and/or data sources 
used to obtain values for the source-specific parameters, chemical-
specific parameters, unsaturated zone parameters, saturated zone 
parameters, and receptor well location parameters. Because the 
groundwater pathway analysis was performed in Monte Carlo mode, all 
parameters are in principle described by their probability 
distributions. Details on the actual distributions used are provided in 
the background documents (USEPA, 1995a-g). Probability distributions 
used for the unsaturated zone parameters, the saturated zone 
parameters, and receptor well location parameters were the same for all 
waste management scenarios and individual constituents that were 
analyzed for today's exit.
(5) Waste Management Scenarios
    The waste management unit represents the source term in the fate 
and transport model for the waste management scenarios evaluated for 
groundwater contamination. In the modeling framework, the source is 
defined in terms of four key parameters: (i) Waste unit area, (ii) 
Leachate flux (infiltration) rate, (iii) Leachate concentration, and 
(iv) Duration of leachate pulse. The first of these parameters, waste 
unit area, was determined from the nationwide OSW survey of industrial 
Subtitle D waste management facilities (USEPA, 1995 a-b). After 
screening out records with unreliable waste site area and/or volume, 
the OSW Industrial Subtitle D survey provides data on location, area 
and volume of 790 landfills, 1655 surface impoundments, 774 waste 
piles, and 311 land application sites nationwide. The weighted 
distributions of waste unit characteristics used as input to the model 
are based on the results of the survey.
    The leachate flux, or infiltration rate, and duration of the 
leachate pulse are determined from the design and operational 
characteristics of the waste management scenario being modeled. 
Consideration of a leachate pulse of finite duration is a fundamental 
aspect of the present analysis and distinguishes it from the continuous 
source (infinite source) assumption used for the 1990 Toxicity 
Characteristic (TC) Rule (55 FR 11798). It should be emphasized though 
that the results of the finite source analysis are not necessarily 
different from those of the continuous source analysis. If the source 
leaching duration is long enough to drive the maximum receptor well 
concentration to its steady state value, the finite source and 
continuous source analyses are in fact the same. In practice, the 
distinction between continuous source and finite source analysis is the 
most important for chemicals which are subjects to sorption, 
speciation, and/or degradation, including hydrolyzing organics and 
metals.
    The leachate concentration of specific constituents in the waste 
forms the basis for regulating the wastes. The leachate concentration 
is not specified a-priori, but rather it is back-calculated at the end 
of the Monte Carlo analysis to satisfy the regulatory criterion that 
the 

[[Page 66370]]
maximum groundwater exposure concentration should be at, or below, the 
constituent-specific health-based drinking water standard, in at least 
90 % of the cases.
    The following sections present background on the determination of 
the source parameters for each waste management scenario.
    Landfills.--The key characteristic of the landfill scenario is that 
the duration of the leachate pulse is independent of the operational 
life of the waste management unit, i.e., the period of time required to 
fill the landfill. The landfill is taken to be filled to capacity and 
covered when leaching begins. The time period during which the landfill 
is filled-up, usually on the order of 20 years, is considered to be 
small relative to the time required to leach all of the constituent 
mass out of the landfill. The model simulation results indicate that 
this assumption is not unreasonable; the model calculated leaching 
duration (see below) is typically on the order of several hundred 
years.
    The leachate flux, or infiltration rate, is determined using the 
HELP model. The net infiltration rate is calculated using a water 
balance approach, which considers precipitation, evapo-transpiration, 
and surface run-off. The HELP model was used to calculate landfill 
infiltration rates for a representative subtitle D landfill with 2-foot 
earthen cover, and no liner or leachate collection system, using 
climatic data from 97 climatic stations located throughout the US. 
These correspond to the reasonable worst case assumptions as explained 
in the Risk Assessment Background Document (USEPA, 1995b). The model 
calculates the daily water balance for the total period for which 
climatic data are available. For each waste site in the OSW survey, an 
infiltration rate was calculated using the data from the closest 
climate station (USEPA, 1995b).
    In the landfill scenario, the duration of the leaching period is 
not prescribed. Instead it is calculated as part of the Monte Carlo 
simulation from the total mass of constituent in the landfill, and the 
rate of leaching. This relationship is derived from a straight-forward 
mass balance principles. The methodology is documented in the 
Background Document for the Finite Source Procedure (USEPA, 1995-c); 
only the most salient aspects are presented here.
    The duration of the leachate pulse, Tp, is determined by the 
total mass of constituent that is initially present in the landfill, 
and the rate at which the constituent is removed by leaching:

Aw . d . Fh . Phw . CW=Aw . I . CL . 
TP
or
TP={d . Fh . Phw} over {I} CW over CL where
    Aw=Area of the waste unit (m\2\),
    d=Depth of waste unit (m),
    Fh=Fraction of waste unit volume occupied by this waste,
    Phw=Density of the waste (g/cm\3\),
    I=Leachate flux (Infiltration) rate (m/y),
    CW=Constituent waste concentration (mg/kg), and
    CL=Constituent leachate concentration (mg/L).

    The determination of Tp according to (2) tacitly assumes that 
the constituent does not degrade inside the waste unit, does not 
consider removal by mechanisms other than leaching (e.g., 
volatilization), and assumes that all of the constituent mass will 
eventually leach out. The formulation given above also assumes that the 
leachate concentration, CL, remains constant until all of the 
constituent mass has leached out. The methodology was adapted to handle 
a time-varying leachate concentration, e.g., a gradually diminishing 
leachate concentration to represent the depletion of the contaminant 
mass in the landfill over time. If it is assumed that the leaching of 
the constituent from the waste into the water phase is controlled by a 
linear equilibrium partitioning process, the reduction of the leachate 
concentration with time can be modeled as a first-order decay process 
(EPA, 1995c):

CL(t)=CL0e{-t}
where
    CL0=Initial leaching concentration (mg/L)
    =Apparent decay constant (y-1)
    t=Time (y)

The rate at which the leachate concentration is reduced is determined 
by the coefficient , which is given by:

={I} over [{d FhwPhw}{CW over CL0}]

Using (3), the leachate concentration will gradually and asymptotically 
be reduced to zero. The total amount of constituent that is released 
into the subsurface will be the same whether a constant leachate 
concentration of finite duration, or a gradually diminishing leachate 
concentration is assumed. In the latter case, the duration of the 
release period is longer, but the average leachate concentration lower, 
as compared to the former case.
    It can be seen from either (2) or (4) that the duration of the 
leachate pulse, or the rate of depletion, respectively, can be 
expressed as a function of the initial leachate concentration, CL. 
For the modeling analyses, equation (3) was used for organic 
constituents. The underlying assumption that the concentration is 
controlled by linear equilibrium partitioning is reasonable for organic 
constituents. For metals, the pulse release option (equation 2) with 
constant leaching concentration was used.
    The calculation of Tp (or ) requires a number of 
ancillary source and waste parameters. These are the depth of the waste 
unit (d), the fraction of the waste unit occupied by the waste 
(Fh), and the waste density (Phw). The waste unit depth is 
obtained directly from the OSW waste site survey. The survey provides 
data on both landfill areas and volumes, which allows the depth to be 
calculated for any landfill selected during the Monte Carlo simulation. 
The fraction of waste in the landfill is assigned a uniform 
distribution with lower and upper limits of 0.036 and 1.0, 
respectively, based on analysis of waste composition in Subtitle D 
landfills (EPA, 1995). The lower bound assures that the waste unit will 
always contains a minimum amount of the waste of concern. The waste 
density is assigned a value based on reported densities of hazardous 
waste, and varies between 0.7 and 2.1 g/cm\3\ (EPA, 1995c).
    Surface Impoundment.--The surface impoundment waste management 
scenario is that of a non-hazardous waste industrial impoundment. The 
area of the impoundment is obtained from the OSW Subtitle D Industrial 
Survey (USEPA 1995 b). No direct data is available on the rate of 
infiltration from surface impoundments. The rate of infiltration from 
the impoundment is calculated inside the EPACMTP fate and transport 
model. The rate of infiltration is calculated, using Darcy's Law, as a 
function of surface impoundment depth, and hydraulic conductivity and 
thickness of a low-permeability sediment layer at the base of the 
impoundment.
    Impoundment depth is obtained from the OSW survey, for each 
impoundment site in the survey, in the same way as the landfill depth 
is obtained (see above). The sediment layer at the base of the 
impoundment is taken to be 2 feet thick, and have an effective 
equivalent saturated conductivity of 10-7 cm/s . These values were 
selected in recognition of the fact that most non-hazardous waste 
surface impoundments do have some kind of liners in place (USEPA, 
1995b). During the Monte Carlo fate and transport simulation, the 
infiltration rate is calculated using the impoundment depth value for 
the specific unit selected for each Monte Carlo realization.
    The leachate concentration again is not determined a priori, but is 
determined after the analysis, based on 

[[Page 66371]]
the desired regulatory protection level (90th percentile). The surface 
impoundment is taken to have a 20-year operational life. After this 
period, the impoundment may be filled in, or simply abandoned. In the 
latter case, the waste in the impoundment will drain and/or evaporate 
relatively quickly. In the modeling analysis, the duration of the 
leaching period is therefore set equal to 20-years.
    Waste Pile.--The waste pile management scenario is conceptually 
similar to that of the landfill, but differs in a number of key 
aspects. In contrast to landfills which represent a long-term waste 
management scenario, waste piles represent a more temporary management 
scenario. During the operational life of the waste pile, it may be 
regarded as an uncovered landfill. Typically at the end of the active 
life of a waste pile, the waste material is either removed for land 
filling, or the waste pile is covered and left in place. If the waste 
is removed, there is no longer a source of potential contamination. If 
a waste pile is covered and left in place, it then becomes equivalent 
to a landfill, and consequently is to be regulated as a landfill. For 
the analyses, therefore, only the groundwater impacts associated with 
the period that the waste pile is active, are considered.
    Data on the waste pile area are obtained from the OSW Subtitle D 
survey. Infiltration rates for the waste pile are obtained by treating 
the waste pile as an uncovered landfill. HELP model derived landfill 
infiltration rates assuming a sandy loam soil cover were used to assign 
infiltration rates for waste piles. A sandy loam cover represents the 
most permeable cover considered for the landfill scenario, and most 
closely resembles a situation in which no cover is present. The 
methodology for assigning an infiltration rate to any specific waste 
pile in the OSW survey follows that used for landfills (see above).
    An active life of 20 years is assumed for the waste pile. This also 
determines the duration of the leaching period. As with the landfill 
and surface impoundment scenario, the leachate concentration is 
determined at the end of the analysis, to satisfy the regulatory 
protection level.
    Land Application Units.--Data on the location, area and waste 
application rates at industrial land application sites were obtained 
from the OSW survey of industrial Subtitle D sites. Location-specific 
infiltration rates were estimated for each land application site by 
applying the HELP model, using climatic data from the nearest climate 
station. Because wastes applied at land application sites typically 
have a high liquid content, this factor was accounted for in the water 
balance calculations. An annual waste application rate of six inches of 
waste, containing 85% water was assumed. This is typical of sludges 
which constitute a large fraction of waste at land application sites. 
Therefore, an additional 5.1 inches of water were added to the natural 
precipitation for the water balance evaluation at each land application 
site.
    The leaching duration for the land application unit was set to 40 
years, consistent with the release period modeled for the air pathway. 
No reliable data were available for the active life of land application 
units. Using a longer value than for surface impoundments and waste 
piles is warranted because part of the applied waste material may 
remain in the soil at the end of the active life of a land application 
unit, and may continue as a source of contaminant leaching.
(6) Determination of Regulatory Waste and Leachate Concentration Limits
    The objective of the Monte Carlo fate and transport analysis is the 
determination of regulatory limits for the concentration of individual 
toxic constituents in the leachate, CL. These limits are 
determined so as to satisfy the regulatory criterion that disposal of a 
waste in a subtitle D waste management unit should not lead to an 
exceedance of the health-based value or the drinking water standard, at 
a receptor well placed down gradient from the waste unit, in at least 
90% of the cases.
    The CL limits are specific to each waste management scenario, 
and are also constituent specific. CL limits are constituent 
specific because of their dependence on constituent specific health-
based standards, as well as on constituent specific fate and transport 
characteristics that affect the concentration received at the receptor 
well. The latter factors are discussed in the following section; this 
section discusses the determination of regulatory CL thresholds.
    Using Equation (2) or (3) and (4), the groundwater exposure 
concentration calculated by the fate and transport model can be 
expressed as a function CL. All other parameters used in the 
modeling analysis are obtained from prescribed probability 
distributions. Consequently, by comparing the predicted exposure 
concentration to the appropriate regulatory standard, e.g., health-
based value or a drinking-water standard, threshold levels of CL, 
can be calculated. Wastes for which the leachate concentration exceeds 
the CL threshold would not be exempted. Because the Monte Carlo 
analysis produces a probability distribution of exposure 
concentrations, the back-calculation of CL threshold levels can be 
performed for any desired level of protection.
     For those constituents that degrade (see next subsection) and 
produce toxic degradation products, the development of regulatory 
threshold values for CL considers not only the exposure 
concentration and toxicity of the parent constituent, but also the 
exposure concentration and toxicity of toxic transformation products. 
For instance, consider two waste constituents that have similar 
toxicity values, i.e., similar health-based levels, as well as similar 
fate and transport characteristics, so that they show comparable values 
for the model simulated receptor well exposure concentration. However, 
if one of the two chemicals produces toxic off-spring, but the other 
chemical does not, the chemical which has toxic daughter products will 
have more stringent limits for CL.
(7) Chemical--Specific Fate and Transport Processes
    The Monte Carlo fate and transport analysis considers chemical-
specific sorption and hydrolysis (degradation) characteristics. These 
characteristics directly affect the model-predicted groundwater 
exposure concentration. Chemicals which are subject to sorption and/or 
hydrolysis will exhibit lower exposure concentration as compared to 
non-sorbing, non-degrading chemicals. This translates into higher 
regulatory waste and concentration limits. Two broad groups of 
chemicals are considered under today's proposal. They are organic 
constituents and metals.
    Organic Constituents.--Organic constituents account for the largest 
group of chemicals addressed under today's proposal. The groundwater 
pathway analyses were performed for a total of 222 organic 
constituents. The fate and transport analysis accounts for sorption of 
organics onto soil and aquifer organic matter, as expressed by a 
chemical-specific organic-carbon partition coefficient (Koc), and 
degradation due to hydrolysis reactions, as expressed by chemical-
specific hydrolysis constants. Sorption is modeled as a reversible, 
linear equilibrium process. Degradation due to hydrolysis is modeled as 
a first-order kinetic process. The groundwater pathway analysis 
utilizes a comprehensive set of Koc values and hydrolysis rate 
constants compiled by the EPA-ORD (Environmental Fate 

[[Page 66372]]
Constants for Organic Chemicals Under Consideration for EPA's Hazardous 
Waste Identification Projects , EPA/600/R-93/132). Chemicals with 
identical Koc values and hydrolysis constants will exhibit the same 
fate and transport behavior, and given the same leachate concentration 
and leaching period, they will result in the same exposure 
concentration. Note, however, that they may still have different 
regulatory leachate concentration limits, if they have different 
health-based drinking water standards and/or produce toxic 
transformation products.
    For the groundwater pathway analysis, organic constituents with a 
hydrolysis half-life of 6,900 years or less (first-order degradation 
rate of 10-4 or greater) were classified as degraders, the 
remainder were classified as non-degraders. The EPACMTP can simulate 
the formation and subsequent fate and transport of transformation 
daughter products, enabling the groundwater exposure concentrations of 
any toxic transformation products to be determined and, therefore, 
included in the determination of leachate concentration thresholds.
    It has been established, by analyzing modeling results for 
different constituents with a range of sorption and degradation 
characteristics that, after normalizing the results against the 
chemical-specific HBN/MCL, the effect of sorption and degradation on 
the regulatory values can be expressed as a function of the Koc and 
hydrolysis rate coefficients, using a straight-forward scaling 
relationship. After these relationships have been established, it is 
not actually necessary to conduct the Monte Carlo fate and transport 
computer simulations for each individual constituent. Instead, for each 
waste management scenario of concern, a set of reference CL values 
are generated by running the Monte Carlo model for a selected range of 
values of Koc and hydrolysis rate coefficients using a normalized HBN/
MCL of 1 mg/L. Constituent-specific CLMIN values are then 
determined in two steps: First, the reference curves are scaled to the 
constituent specific Koc value, and (for degraders) hydrolysis rate 
coefficients. Secondly, an adjustment is made for the constituent-
specific value of the drinking water standard. The final values of 
CLMIN are obtained by multiplying the concentration limits 
based on the normalized drinking water standard, by the actual value of 
the drinking water standard of that particular constituent. For 
constituents with toxic transformation products, this procedure is 
repeated for the transformation products, to find the minimum values of 
CL (CLMIN) which ensure that the exposure concentrations 
of the parent constituent and any daughter products will not be 
exceeded. The benefit of this approach is that if additional 
constituents are to be regulated, or a different value of the drinking 
water standard HBN/MCL, the appropriate CLMIN can be 
determined with less effort, because it is not necessary to repeat the 
time-consuming complete Monte Carlo simulation.
    Metals.--Fate and transport of metals in the subsurface may be 
controlled by complex geochemical interactions. To account for these 
processes, the OSW has developed and implemented a modeling approach 
which utilizes the MINTEQA2 metals speciation model in conjunction with 
the EPACMTP subsurface fate and transport model. The MINTEQ model has 
been applied to generate effective sorption isotherms reflecting 
variations in four geochemical master variables affecting metals fate 
and transport. These factors are: Ph, leachate organic matter natural 
organic matter in the soil or aquifer, and ironhydroxide content. Each 
of these parameters has a range of values, reflecting their nationwide 
probability.

                                       Table 3.--EPACMTP Modeling Options                                       
----------------------------------------------------------------------------------------------------------------
                                                                                                                
----------------------------------------------------------------------------------------------------------------
Management Scenarios..........................................................  Industrial Subtitle D: (i)      
                                                                                 Landfill; (ii) Surface         
                                                                                 Impoundment; (iii) Waste Pile; 
                                                                                 and (iv) Land Application Unit.
Modeling Scenario.............................................................  Finite Source Monte Carlo.      
Regulatory Protection Level...................................................  90% (yields an approximate DAF  
                                                                                 of 10 for a continuous source  
                                                                                 landfill).                     
Source Parameters:                                                                                              
    Waste Unit Area...........................................................  Site based, form OSW Industrial 
                                                                                 Subtitle D Survey.             
    Waste Unit Volume.........................................................  Site based, from OSW Industrial 
                                                                                 Subtitle D Survey.             
    Infiltration Rate:                                                                                          
        Landfill..............................................................  Site-based, derived from water  
                                                                                 balance using HELP model.      
        Surface Impoundment...................................................  Site-based, derived from        
                                                                                 impoundment depth using Darcy's
                                                                                 law.                           
        Waste Pile............................................................  Site-based derived from water   
                                                                                 balance using HELP model.      
        Land Application Unit.................................................  Site-based, derived from water  
                                                                                 balance using HELP model.      
    Leaching Duration:                                                                                          
        Landfill..............................................................  Derived, continues until all    
                                                                                 constituent has leached out.   
        Surface Impoundment...................................................  20 years (operational life of   
                                                                                 waste unit).                   
        Waste Pile Land.......................................................  20 years (operational life of   
                                                                                 waste unit).                   
        Application Unit......................................................  40 years.                       
Chemical Specific Parameters:                                                                                   
    Decay Rate:                                                                                                 
        Organics..............................................................  Hydrolysis rates based on       
                                                                                 measurements or based on       
                                                                                 appropriate structure-activity 
                                                                                 relationships.                 
        Metals................................................................  No decay.                       
    Sorption:                                                                                                   
        Organics..............................................................  Koc estimated from Kow, which is
                                                                                 based on measurements or based 
                                                                                 on appropriate structure-      
                                                                                 activity relationships.        
        Metals................................................................  MINTEQ sorption isotherms (Pb,  
                                                                                 Hg, Ni, Cr (III), Ba, Cd).     
                                                                                pH dependent isotherms (As, Cr  
                                                                                 (VI), Se (VI), Th)             
Unsaturated Zone Parameters:                                                                                    
    Depth to groundwater......................................................  Site-based, from API/USGS       
                                                                                 hydrogeologic database.        
    Soil Hydraulic Parameters.................................................  National distribution for the   
                                                                                 main soil types.               
    Fraction Organic Carbon...................................................  National distribution for the   
                                                                                 main soil types.               
    Bulk Density..............................................................  National distribution for the   
                                                                                 main soil types.               
Saturated Zone Parameters:                                                                                      
    Recharge Rate.............................................................  Site-based, derived from        
                                                                                 precipitation/evaporation and  
                                                                                 soil type.                     

[[Page 66373]]
                                                                                                                
    Saturated Thickness.......................................................  Site-based, from API/USGS       
                                                                                 hydrogeologic database.        
    Hydraulic Conductivity....................................................  Site-based, from API/USGS       
                                                                                 hydrogeologic database.        
    Porosity..................................................................  Effective porosity derived from 
                                                                                 national distribution of       
                                                                                 aquifer particle diameter.     
    Bulk Density..............................................................  Derived from porosity.          
    Dispersivity..............................................................  Derived from a national         
                                                                                 distribution and is based on   
                                                                                 distance to the receptor well. 
    Groundwater Temperature...................................................  Site-based, from USGS regional  
                                                                                 temperature map.               
    Fraction Organic Carbon...................................................  National distribution, from EPA 
                                                                                 STORET database.               
    pH........................................................................  National distribution, from EPA 
                                                                                 STORET database.               
Receptor Well Location:                                                                                         
    Radial Distance...........................................................  Nationwide distribution based   
                                                                                 the survey.                    
    Angle Off-Center..........................................................  Uniform within  90  
                                                                                 deg. from plume centerline.    
    Depth of Intake Point.....................................................  (No restriction to be within    
                                                                                 plume) Uniform throughout      
                                                                                 saturated thickness of aquifer.
----------------------------------------------------------------------------------------------------------------



4. Other Risk Assessment Issues
a. Differences Between the Groundwater and Non-groundwater Analyses
    As mentioned previously, the Agency conducted separate analyses for 
the evaluation of risks from groundwater and non-groundwater pathways. 
The groundwater pathways relied on a full Monte Carlo analysis; whereas 
the non-groundwater pathway analyses were performed using high-end and 
central tendency parameters, consistent EPA's risk characterization 
guidance (EPA 1995).
    Although the approaches to the modeling differed, the Agency used 
the same data for parameter inputs (i.e., OSW's Industrial Subtitle D 
Survey, U.S. EPA 1986) to describe the waste management units common to 
both analyses (i.e, surface impoundments, waste piles, and land 
application units). However, even though the same data were used, some 
differences exist based on the different modeling approaches. These 
differences are discussed below.
(1) Infiltration
    For the groundwater pathway analysis, the Agency used the HELP 
model to calculate the net infiltration rate for landfills, land 
application units and waste piles, as a function of regional climatic 
conditions and waste unit design characteristics (see EPACMTP 
background Document). The analysis used the meteorological data from 93 
meteorological stations located throughout the United States to develop 
infiltration rate distributions using the HELP model.
    For the non-groundwater analysis, the Agency used rainfall to 
calculate the recharge rate. The rainfall was selected from 29 
meteorological stations distributed among 9 climate regions. However, 
the method for selecting the rainfall factor differed between the air 
release pathways and the overland release pathways.
     For the air release pathways, the Agency conducted a 
sensitivity analysis for each waste management unit type to rank the 29 
meteorological stations with respect to several air modeling outputs, 
including maximum air concentration of pollutants, average air 
concentrations over the agricultural field and water body, and average 
deposition over the agricultural field and water body. Based on these 
sensitivity analyses, the Agency selected a central tendency location 
and high-end location for the air pathway for each of the waste 
management units. Thus, locations with meteorologic data, including the 
rainfall factor, approaching the central tendency and high-end values 
were selected for each waste management unit.
     For the overland release pathways, the Agency ranked the 
rainfall factors from the 29 meteorological stations and selected the 
50th and 90th percentile based on the distribution of the 29 
meteorological stations.
(2) Density of Waste Applied to the Land Application Unit
    The approach used in the groundwater analysis assumed the bulk 
density of the applied waste to be 1 gram per cubic centimeter (g/cc) 
because the waste was assumed to be comprised predominantly of water. 
However, changes in the density of applied waste do not significantly 
affect the results of the groundwater modeling results.
    The approach used in the non-groundwater analysis assumed the bulk 
density of waste to be analogous to the density of sewage sludge (i.e., 
1.4 g/cc). The waste in the LAU is a mixture of industrial waste and 
soil. The central tendency bulk density for soil (i.e., 1.5 g/cc) is 
similar to the bulk density assumed for industrial waste. Because the 
waste is incorporated into soil, the properties of the waste/soil 
mixture are needed. There is little variability in bulk density for the 
type of soil used in the analysis (i.e., loam), thus, the same value 
was used for central tendency and high-end estimates of the waste/soil 
mixture bulk density.
(3) Unsaturated Zone Characteristics
    The groundwater pathway analysis used the characteristics (e.g., 
percent organic matter, saturated hydraulic conductivity) of the entire 
unsaturated zone as input into the modeling analysis. The non-
groundwater pathway analysis used as input the characteristics of only 
the upper portions of the unsaturated zone because these 
characteristics were those significant for the surface exposure 
pathways.
(4) Hydrolysis Rates
    The hydrolysis rate for a chemical constituent is used in the Monte 
Carlo groundwater pathway analysis as a function of temperature and pH 
of the groundwater at the Monte Carlo realized site. The Agency used 
hydrolysis rates for constituents that have been measured through 
appropriate structure activity relationships. They have been reviewed 
by a panel of experts from the Agency's Office of Research and 
Development (USEPA, 1993). The non-groundwater pathway analysis used 
hydrolysis rates from the ``Handbook of Environmental Fate and Exposure 
Data for Organic Chemicals'' (Howard et. al, 1993).
b. Other Groundwater Pathway Analysis Issues
(1) Use of 1,000 Year Versus 10,000 Year Exposure Time Horizon
    The Agency's proposal is based on a 10,000 year time horizon for 
the groundwater pathway. This means that the determination of leachate 
concentration limits is based on the highest (30-year average) 
concentration that occurs within 10,000 years from the start of the 
release. Although this longer time horizon has been used in other 
programs (U.S. Nuclear Regulatory 

[[Page 66374]]
Commission and U.S. Department of Energy), the Agency is considering 
using 1,000 years as an alternative time horizon. The Agency requests 
comment on this issue which is described in more detail below.
    Using this shorter time horizon results in an increase of the 
leachate concentration limit for a number of constituents. The 
constituents affected are those which are strongly sorbed in the 
subsurface, and which therefore tend to migrate slowly. These 
constituents include organics with retardation factors (R) 
significantly greater than one. The organic carbon partition 
coefficient (koc) values for these constituents are about 3,500 g/
cm3 or greater, and certain metals such as lead and chromium(III). 
For organic constituents with koc values less than about 3,500 g/
cm3, the highest receptor well exposure concentration is generally 
reached in less than 1,000 years. Reducing the modeling time horizon 
from 10,000 to 1,000 years therefore does not affect the results of the 
pathway analysis for these constituents. The effect of using a 1,000 
year versus a 10,000 year time horizon is illustrated in Table 4. The 
constituent-specific differences are shown in Table B-1 of appendix B 
to the preamble. The table is based on a landfill waste management 
scenario, and all constituents are assumed to have identical toxicity 
values and not be subject to hydrolysis. For reference, the leachate 
concentration limit for constituents with koc=0 (no sorption, 
R=1), and a 10,000 year time horizon is equal to 1.0 mg/L. This table 
shows that the increase in leachate concentration limit for organic 
constituents is affected for a shorter modeling horizon (1,000 years) 
only when koc values (or R values) are very large. (About fifteen 
percent, out of a total of approximately 200, including eight metals, 
fall into this category.) The effect of hydrolysis rate is not 
considered in results shown in the table. While hydrolysis influences 
the magnitude of the exposure concentration at a receptor well, the 
time that it takes for a contaminant to reach the receptor well is 
independent from the chemical-specific hydrolysis rate. It is, however, 
strongly influenced by chemical-specific sorption characteristics, 
which for organics are expressed in terms of koc or R values.

 Table 4.--Effect of 1,000 Year Versus 10,000 Year Modeling Time Horizon
                     on Leachate Concentration Limit                    
------------------------------------------------------------------------
                                                      10,000     1,000  
                    koc (cm3/)                        years      years  
------------------------------------------------------------------------
0.0...............................................        1.0        1.0
3,384.............................................        1.0        1.0
(R=10)                                                                  
37,224............................................        1.0         60
(R=100)...........................................                      
------------------------------------------------------------------------

(2) Implementation of Parameter Bounds in Monte Carlo Procedure
    The Monte Carlo modeling procedure used in the groundwater pathway 
analysis uses data on waste site location from the EPA's Industrial 
Subtitle D Survey (USEPA, 1986). These data are combined with other 
data sets for climatic and hydrogeological parameters. Auxiliary 
parameters for which no direct data is available are calculated 
internally in the model. For instance, ground-water velocity is 
calculated from hydraulic conductivity, gradient and effective 
porosity, and the dispersivity is calculated from the receptor well 
distance (See EPACMTP Background Document and User's Manual). Each 
parameter furthermore can have specified upper and lower bounds to 
guard against the possibility that physically infeasible parameters 
and/or parameter combinations are not used. When the latter condition 
occurs, the particular Monte Carlo realization is rejected, and another 
realization is generated. The Agency is considering an alternative 
procedure in which only the offending parameter is regenerated, or, if 
necessary, set equal to its upper or lower bound to avoid selection of 
values beyond the minimum to the maximum values range. In first case, 
the frequency distribution of parameter values generated by the Monte 
Carlo module, may be different from its input distribution. The Agency 
has determined that the two alternative procedures have little impact 
on the overall modeling results in the case of landfills and land 
application units, but that the default procedure tends to favor the 
selection of sites with larger waste unit area in the case of waste 
piles and surface impoundments. Therefore it produces more conservative 
(lower) values for the final leachate concentration limits. The 
analysis results show that for the two alternative Monte Carlo 
procedures for surface impoundments, the default procedure results in a 
leachate concentration limit of 1.0 mg/L, the alternative procedure 
results in a concentration limit of about 31 mg/L for a chemical with 
R=1. The effect of changes in the hydrolysis rate or the R value on the 
resultant regulatory leachate concentration do not impact the results 
obtained by using the alternative Monte Carlo procedure described in 
this subsection. The Agency is also soliciting comments on the Monte 
Carlo parameter rejection procedure used for the results presented in 
this subsection.
(3) Hydraulic Conductivity of Surface Impoundment Bottom Layer
    The surface impoundment scenario modeled in the groundwater pathway 
analysis incorporates a 2 feet thick layer at the base of the 
impoundment. In the base case for this proposal, the layer is assigned 
a hydraulic conductivity of 10-7 cm/sec. The Agency recognizes that 
this value may or may not be appropriate value for bottom sediments as 
a nationwide typical for industrial Subtitle D surface impoundments. To 
evaluate the impact of varying this parameter, the Agency has compared 
modeling results obtained using a 10 times higher conductivity of 10-6 
cm/sec. A higher conductivity value corresponds to a greater leachate 
flux from the impoundment, and generally higher receptor well 
concentrations, which translates into a more conservative (lower) 
regulatory leachate concentration limit. The regulatory limit 
calculated for a conductivity value of 10-7 cm/sec is 1.0 mg/L, 
the corresponding value for a conductivity of 10-6 cm/sec would be 
0.35 mg/L. The effect of changes in hydraulic conductivity on the 
results is believed to be independent of the sorption or the hydrolysis 
characteristics of the chemical. The Agency is inviting comments on the 
appropriate value for the hydraulic conductivity of the bottom sediment 
layer for industrial D surface impoundments. In addition, the Agency 
requests the submission of hydraulic conductivity data for industrial 
Subtitle D surface impoundment bottom sludges.
(4) Waste Pile Infiltration Rates
    The Agency used the HELP model to calculate the net infiltration 
rate for landfills, land application units and waste piles, as a 
function of regional climatic conditions and waste unit design 
characteristics (see EPACMTP background Document). For waste piles, the 
Agency considered two alternatives. The procedure used in the base case 
considered a waste pile, for the purpose of estimating infiltration 
rates, to be similar to an uncovered landfill. The Monte Carlo modeling 
analysis therefore used landfill infiltration rates corresponding to 
the most permeable (sandy loam) of the three cover types 

[[Page 66375]]
used for landfill modeling. As an alternative, the Agency has used the 
HELP model to calculate infiltration rates for waste piles directly. In 
the initial evaluation, the runoff used in the water balance 
calculation was computed by the HELP model as a function of soil 
texture and vegetative cover (bare ground).The Agency has evaluated the 
impact of representative bare, but unevenly surfaced, waste piles on 
simulated runoff using the HELP model. A comparison of the impact of 
using this alternative procedure against the values used in this 
proposal for the base case, on the regulatory leachate concentration 
limit, was conducted. The comparison of regulatory leachate 
concentration limits is based on a non-degrading, non-sorbing 
constituent, which has a concentration limit of 1.0 mg/L in the 
proposal. Using the alternative procedure, the corresponding leachate 
concentration level changes to 0.77. The Agency is inviting comments on 
the two methods for the waste piles for the estimation of infiltration 
rates through them. If you have any data and other information to 
support your comment, send it along with your comments to the Docket.
(5) Land Application Unit Infiltration Rates
    In the calculation of infiltration rates for land application units 
for the base case in the proposal, it was assumed that land application 
units receive, on average, 1,295.4 m\3\ha (5.1 inches) of water 
annually through the application of the waste. This amount of water was 
included in the HELP model water balance calculation, resulting in an 
increased net infiltration as compared to ambient conditions. The waste 
application rate may or may not represent true field situations. As an 
alternative to the modeling procedure used for the base case of this 
proposal, the Agency evaluated the effect of using ambient recharge 
rates, i.e., the application of waste does not significantly alter the 
water balance, on the calculated leachate concentration limits. The 
comparison of this alternative with the procedure used for the base 
case shows that the regulatory leachate concentration limits for a non-
degrading, non-sorbing constituent in land application units changes to 
1.12 mg/L from 1.0 mg/L for the procedure used in the base case.
    (6) Aggregate Effects of Alternative Groundwater Modeling 
Procedures and Data
    The preceding sections have presented the effect of alternative 
modeling options and data sources that have been considered by the 
Agency. A consequence of the Monte Carlo exposure modeling approach is 
that the effects of changes in model parameters are not always linearly 
additive; rather the aggregate effect of changing multiple parameters 
or options may be to either magnify or reduce the effect of the 
individual changes. The Agency, therefore, has conducted modeling 
analyses of the aggregate effect of the alternatives discussed above 
for each of the four waste management scenarios. In addition to the 
alternatives presented in the preceding subsections, a modification was 
also made in the procedure for modeling waste sites for which the 
corresponding hydrogeological region was initially assigned as ``not 
classifiable''. Rather than ignoring the small fraction of sites 
involved, they were incorporated into the analysis by assigning them 
nationwide average values for the groundwater parameters. Table 5 
presents the aggregate effect of all changes for each of the four waste 
management scenarios modeled. The modeling results correspond to a non-
degrading, non-sorbing constituent. The leachate concentration limits 
are normalized with respect to a value of 1.0 mg/L for the landfill 
scenario, under the modeling procedure for the base case of this 
proposal. The results are presented for a 1,000 year time horizon; 
however for a non-sorbing constituent, these same results also hold for 
the 10,000 year time horizon.

     Table 5.--Aggregate Effect of Modeling Alternatives on Leachate    
  Concentration Limits for Non-Degrading, Non-Sorbing Constituents for  
                     Four Waste Management Scenarios                    
------------------------------------------------------------------------
                                                     HWIR    Alternative
            Waste management scenario              proposal    Options  
------------------------------------------------------------------------
Landfill........................................        1.0        0.71 
Surface Impoundment.............................       0.22        0.27 
Waste Pile......................................       0.29         484 
Land Application Unit...........................       0.08        0.22 
------------------------------------------------------------------------

    Table 5 shows that, except for landfills, the aggregate effect of 
the combined alternative options is a less conservative (higher) 
leachate concentration limit. For landfills, adoption of the 
alternative modeling options would have resulted in a 30 % less 
stringent regulatory leachate limit for the groundwater pathway for 
non-sorbing and non-degrading constituents. For surface impoundments, 
there is little overall impact because the opposing effects of 
increasing the impeding layer hydraulic conductivity, and the 
alternative Monte Carlo procedure for handling parameter bound 
exceedances, nearly cancel out. For waste piles on the other hand, the 
procedure used for the base case, results in a significantly more 
conservative leachate concentration limit as compared to the 
alternative modeling options. This is due to the handling of parameter 
exceedances in the Monte Carlo simulation. Because many waste piles 
have very small sizes (surface areas), the alternative Monte Carlo 
procedure has a large impact. For land application units, the 
procedures used in the proposal for the base case also result in a more 
conservative regulatory limit as compared to the alternative modeling 
options. The contributing factors are much the same as for waste piles, 
but the overall impact is much smaller, primarily because there are 
only few land application units with very small areas.

F. Additional Eco-Receptor Considerations

    EPA considered two different policy goals with respect to 
protection of terrestrial ecological receptors (i.e., soil fauna, 
birds, mammals, and plants). One goal protected terrestrial ecological 
receptors outside the boundaries of the waste management site, thus, 
the constituent had to travel off-site before exposures would be 
assessed. The alternative goal protected terrestrial ecological 
receptors on the closed land application site.
    The Agency chose to propose exit levels based on off-site impacts 
for several reasons. One reason is that there are many land use 
decisions that significantly affect terrestrial ecological receptors on 
the property of a party making those decisions (e.g., a decision to 
pave a portion of land as a parking lot). EPA does not generally 
regulate those sort of decisions. However, many impacts are judged 
through local zoning regulations. Congress has typically asked EPA or 
other Federal entities to regulate activities on a property when there 
are significant off-site impacts, such as a groundwater plume that 
migrates, an air release that moves beyond the property, a wetland 
(located on the property) that is a significant resource for migratory 
birds and has broader ecological significance, or an endangered species 
with social values beyond the impact on a specific landowners purview.
    EPA asks for comment, however, on the alternative of protecting 
terrestrial ecological receptors on-site. The rationale for this 
alternative approach would relate to protection from impacts on bird 
and mammal populations, and 

[[Page 66376]]
other ecological receptors, and to the regulation of certain 
constituents that could potentially result in environmental 
consequences that go significantly beyond the bounds of a current waste 
management unit.

G. Background Concentrations in Soils and Other Issues Relating to 
Results

    EPA has compared the exit levels for nonwastewaters to data on the 
variation in mean background concentrations found in soils. For some 
metals, the exit levels calculated based on risks at land application 
units are below 4 mean soil concentrations. One reason exit 
criteria may be below soil concentrations is that these metals 
bioaccumulate, causing greater exposure for higher trophic levels. 
Also, the acceptable levels for some of the metals that would be 
calculated for practices other than land application are significantly 
higher and not below mean soil concentrations.

    \4\ When compared with mean soil background levels provided by 
the USGS, the exit levels are not more that 1 order of magnitude 
more restrictive.
---------------------------------------------------------------------------

    If the final exit levels are below typical soil levels, EPA would 
consider promulgating levels based on concentrations that are either 
typical soil concentrations (national mean levels) or some percentile 
or portion of the naturally-occurring range such as the 10th 
percentile. If the effect of concern is an ecological impact, the 
rationale for using the 10th percentile (or similar figure if the data 
available does not allow that precision) would be that in 90 percent of 
locations, if the soil already contains those or greater levels, the 
ecological receptors existing in the area should already reflect the 
toxicity of the waste material; the rational for using the 10th 
percentile (or similar value) value is that human behavioral practices 
(e.g., treatment of groundwater prior to use) may already reflect 
protection from the potential toxicity of concern. EPA asks for comment 
on whether these are reasonable arguments.
    EPA is concerned, however, that there are also issues of the 
chemical and physical form in which compound or chemicals exist, in 
both natural conditions and in the waste and that a simple comparison 
of total concentrations in soils and in wastes might be misleading 
about potential ecological or human impacts. EPA requests comment on 
these issues. EPA's first preference will be to reexamine the risk 
modeling to identify any inappropriate assumptions or modeling issues 
that may explain the low proposed exit level, and to look more 
carefully at those constituents where this issue only arises from the 
modeling of risks from land application units, to identify potential 
contingent management solutions to this problem.
    Finally, EPA requests comment on whether these arguments could be 
extended to site-specific determinations where information on local 
background constituent concentrations and form in soil are available 
and have been reviewed by a State regulatory authority. EPA assumes 
that such an approach would only apply if the background concentrations 
were more than very localized and the concentrations were naturally-
occurring rather than due to past contamination. If a site-specific 
determination were adopted, two approaches are available that have been 
used in other contexts. One statistical technique for determining 
whether background data conform to a normal distribution assumption 
includes combining the Student-t difference of means test, presented in 
the Permit Guidance Manual on Unsaturated Zone Monitoring for Hazardous 
Waste Land Treatment Units, (EPA, 1986) with the normal tolerance 
interval approach found in Statistical Analysis of Ground Water at RCRA 
Facilities-Interim Final Guidance, (EPA, April 1989). The Student-t 
test compares averaged waste/media concentrations to background 
concentrations, and is used to determine if the waste/media as a whole 
is within a specified criteria. However, even if the waste/media passes 
the Student-t test, individual sample concentrations may still exceed 
the tolerance interval limit. The normal tolerance interval approach is 
used to compare sample concentrations to an upper tolerance value based 
on the background mean, standard deviation, and sample size.
    If such an approach is incorporated into the final rule, it would 
include criteria for defining and collecting adequate background 
samples. More specifically, the facility would be required to identify 
background locations, sample size, soil depth, etc. for at least four 
samples in a ``difference of means'' demonstration, and six to eight 
samples for a ``tolerance of means'' demonstration. The facility would 
also need to demonstrate the normalcy of the sample distribution. The 
Agency would require that this information be included as part of the 
facility's sampling and analysis plan and subject to review by the 
appropriate overseeing authority.
    A more simplified approach would be to establish exit levels at \1/
10\ of the naturally occurring background level. The rationale for 
using \1/10\ is that these levels would not appreciably contribute to 
the overall risk posed by elevated levels in the environmental media. 
EPA requests comment of this approach as well as the rationale.
    Alternatively, the rule could defer any background level 
demonstrations to an omnibus authority for the overseeing agency. Under 
this concept, a claimant could submit information on naturally 
occurring background level and a request for modified exit levels to 
the agency overseeing the exemption process, which would have 
discretion to grant modifications where they are clearly justified. 
Comment is requested on the need for this authority.
    The Agency solicits comments on other appropriate and generic ways 
(1) to identify background levels in soils, and (2) to incorporate the 
existing 40 CFR part 264, subpart F standards for establishing 
background levels for groundwater. Other suggestions that address the 
Agency's intent to promulgate a simplified exemption with little 
reliance on site-specific considerations but also allow for 
consideration of elevated background levels will be considered.
    EPA also observed that some of the exit levels for organic 
chemicals appear relatively high (see, for example, the level for 
xylene). EPA believes that these results occurred primarily because 
these chemicals either are toxic only at relatively high concentrations 
or undergo high dilution during transport. EPA, however, requests 
comment on whether these chemicals are frequently co-disposed and, if 
so, whether they might pose cumulative risks not assessed by the risk 
analysis. EPA is interested in information on issues such as whether a 
waste containing one or more of these constituents at concentrations 
near exit levels would be ignitable or threaten the integrity of 
control measures such as liners.

H. Constituents with Extrapolated Risk-based Levels

    EPA was unable to conduct the risk assessment for 187 of the 376 
constituents on the exit list. In most of these cases, EPA was unable 
to find acceptable human health benchmarks to serve as the starting 
place for the assessment. In a few cases, EPA could not find values for 
critical physical or chemical properties, such as log Kows. Based 
on its past experience, EPA believes it would need at least a year to 
develop a new human health benchmark value for any constituent. EPA has 
less experience with the type of research and peer review needed to 
develop values for physical and chemical properties, but it believes 
that this process also would be time-consuming. 

[[Page 66377]]

    Rather than not consider the 187 constituents for which EPA was 
unable to conduct the risk assessment as potential candidate 
constituents for exit criteria, EPA developed an approach for 
establishing exit criteria for these constituents. The Agency grouped 
the constituents on the exit list into classes, based on chemical 
structure. EPA selected the 50th percentile value from the range of 
modeled risk levels for each chemical class. This 50th percentile value 
serves as the extrapolated risk-based level for the un-modeled 
constituents in the corresponding chemical class. The constituents and 
their 50th percentile extrapolated risk-based levels are presented in a 
background document Background Document to Support the Methodology used 
in Extrapolating Exit Levels to Constituents with no Health-Based 
Benchmarks. EPA is proposing the 50th percentile level to avoid adding 
another conservative assumption to the derivation of exit levels for 
these constituents. EPA believes that the multipathway approach is 
already sufficiently conservative to protect human health and the 
environment even for these chemicals. EPA, however, requests comment on 
the alternative of using the 10th percentile or a different percentile 
from the modeled exit levels from each class. Such an approach would 
reduce the chances that the actual health benchmark for a particular 
level was lower than the extrapolated estimate. However, it would also 
increase the odds that the extrapolated level was higher than needed 
for many constituents. A complete list of extrapolated constituents and 
associated risk levels may be found in appendix C to today's preamble.
    EPA recognizes that this approach to generating exit levels is much 
less sophisticated and precise than the multipathway analysis. 
Nonetheless, EPA prefers it to any of the available alternatives. If 
EPA set no exit levels and made wastes containing any of these 
constituents ineligible for exit, a significant number of waste streams 
would probably be ineligible, even though they may pose no significant 
threat to human health and the environment. EPA's RIA data shows that 
some of these constituents, such as Cyanide and Anthracene, are fairly 
prevalent. Although other constituents, such as those found in the 
commercial chemical products on the P and U lists of hazardous wastes, 
are not very prevalent, they may be significant for generators that 
manage multiple waste streams in centralized wastewater treatment 
plants. In the absence of extrapolated exit criteria, a generator would 
lose its opportunity to claim an exit for an entire combined stream if 
any of these constituents is found in the waste stream. Furthermore, it 
would take a long time to complete the work necessary to conduct 
exposure pathway assessments for any significant number of these 187 
constituents.
    Alternatively, EPA could propose to allow wastes to exit without 
testing for constituents lacking modeled exit levels. EPA, however, 
finds this approach insufficiently protective, especially when it can 
at least approximate likely risk levels as described above.
    Finally, EPA considered the alternative of basing exit levels for 
these constituents on quantitation limits. As explained below, EPA is 
proposing to use EQCs as exit levels where they are higher than a 
constituent's multipathway or extrapolated exit level. (EPA is also 
proposing that wastes with such constituents meet the technology-based 
LDR standards for those constituents prior to exit.) EPA considered 
using this EQC and LDR approach for constituents lacking multipathway 
levels. Such an approach would actually produce more conservative exit 
levels, because EPA would not use extrapolated levels that are higher 
than EQCs. EQCs (and technology-based LDRs), however, are not based on 
risk. EPA prefers the extrapolated approach because it takes into 
account the toxicity and fate and transport of structurally similar 
chemicals. EPA believes it would be unreasonable to continue to 
regulate a chemical because chemistry can detect it, where the 
extrapolation described above suggests that the chemical poses no 
significant risks at the EQC level.
    EPA finds the option of basing exit levels on the extrapolation 
procedure described above to strike a reasonable balance between the 
goals of protecting human health and the environment and eliminating 
regulation of low-risk wastes. EPA, however, requests comment on all of 
the alternatives described in this section.

I. Analytical Considerations

    Some of the proposed exit levels established by the risk assessment 
and the extrapolation methodology are low. In some cases, existing 
analytical methods cannot routinely detect the constituents at those 
levels. EPA is proposing to cap these potential exit levels with 
reasonable analytical quantitation limits. The Agency is proposing 
quantitation limits that represent the lowest levels that can be 
reliably measured within acceptable limits of precision and accuracy 
during routine laboratory operating conditions using appropriate 
methods. These concentrations are referred to as ``exemption 
quantitation criteria,'' or EQCs. It is necessary to specify EQCs 
because a number of the constituents on the exemption list have either 
modeled or extrapolated risk-based levels that are not analytically 
achievable in all matrices. Appendix C to today's preamble lays out the 
comparison between the modeled or extrapolated risk level and the EQC 
for every constituent. Approximately one-quarter of the constituents 
have proposed modeled or extrapolated risk-based levels lower than EQC.
1. Development of Exemption Quantitation Criteria (EQC)
    To develop the EQCs proposed in today's notice, EPA compiled a 
master list of the quantitation limits published for the identified 
constituents in the Third Edition of Test Methods for Evaluating Solid 
Waste, (SW-846), including the first and second updates (both of which 
are widely distributed throughout the regulated community). The Agency 
believes that the resultant EQCs present achievable quantitation limits 
for the proposed exemption constituents in most matrices. The Agency 
requests comment on the proposed quantitation limits as well as any 
data supporting those comments.
    A regulatory action level (e.g., exit levels) must provide a clear 
distinction between those wastes subject to the regulation and those 
excluded. Action levels based on analytical determinations within a 
methods quantitative range can be used to determine regulatory status 
with a high degree of confidence. On the other hand, when an analyte is 
present at a concentration equal to the detection limit (DL) it will be 
detected only half the time. In other words there is a 50% risk of a 
false negative result when the analyte is present at the DL 
concentration. There is, however, a less than 1% risk of false positive 
results at this level. Therefore, regulations set at the detection 
limit would not identify non-compliance reliably.
    The Agency is in the process of re-evaluating EQCs for some 
constituents. Preliminary updated EQCs could not be incorporated into 
today's proposed rule, but have been included in the docket for 
comment.
2. EQCs and LDR Requirements as Exit Levels
    A comparison of the modeled or extrapolated risk-based levels with 
the EQCs reveals a number of cases where 

[[Page 66378]]
quantitative measurement of analyte concentration at the modeled or 
extrapolated risk-based level cannot be reliably achieved, using 
standardized analytical methods. In today's proposed rule, for wastes 
containing constituents with a modeled or extrapolated risk-based level 
lower than the EQC, exit criteria include meeting the EQC along with an 
additional requirement that the waste meet Land Disposal Restrictions 
(LDR) treatment standards from part 268, regardless of whether or not 
the waste is to be land disposed. The exit table for constituents with 
EQCs as exit levels is proposed appendix X of 40 CFR part 261, Table B.
a. EQCs as exit levels
    Only when the comparison between the modeled or extrapolated risk-
based level with that constituent's EQC level reveals that the 
constituent cannot be quantitated at the modeled or extrapolated risk-
based level, does the EQC become the exit level. For example, the 
modeled risk-based level for 2-nitropropane in wastewaters is 0.00019 
g/L. The EQC for 2-nitropropane in wastewaters is 0.0058 
g/L. 2-nitropropane is listed in appendix X, Table B, with an 
exemption level of 0.0058 g/L. In other words, the exemption 
level for 2-nitropropane has been met if the claimant demonstrates that 
the method used can achieve the EQC of 0.0058 g/L in the waste 
matrix, and the level detected by the method does not exceed 0.0058 
g/L.
    The Agency believes that, for those constituents that have a 
modeled or extrapolated risk-based level lower than the achievable 
quantitation limit, demonstration that the constituent is not present 
above the EQC is the most reasonable approach to setting a national 
exemption level. The Agency is proposing that quantitation limits cap 
the modeled or extrapolated risk-based levels because a reliable, 
consistent measure of the constituent below the quantitation limit is 
not achievable. By establishing EQCs as benchmarks (or maximum 
allowable quantitation limits), the Agency is ensuring that all 
exemption demonstrations will achieve acceptable analytical 
sensitivity, and that wastes with high levels of contamination that 
tend to confound analytical protocols are not exempted.
    The Agency requests comments on whether an exemption demonstration 
should be considered adequate if all proper method selection and QC 
procedures are followed and the constituents are not detected, even 
though the EQC level has not been analytically attained. This situation 
could arise even in relatively clean matrices if the constituents bind 
strongly to the matrix or if the constituents degrade rapidly during 
the analysis. However, the Agency would not want the exemption to be 
allowed if the EQC could not be achieved because of interference from 
other contaminants in the matrix, or if inappropriate methodology, 
i.e., sample preparation, cleanup (if necessary), or determinative, was 
used.
    EPA is not proposing that any exit level based on an EQC can serve 
as a ``minimize threat'' level capping current 40 CFR part 268 
treatment standards. Such levels are not sufficiently related to a 
constituent's risk.
b. LDR Requirements for Constituents With EQC Exit Levels
    EPA considered the option of setting exit levels for all 
constituents at their modeled or extrapolated levels, regardless of 
analytical considerations. EPA also considered the alternative of 
making wastes containing constituents with analytical limitations 
ineligible for exit. Both of these options, however, are likely to 
constrain significantly the number of waste streams eligible for exit. 
Approximately one-quarter of the constituents on the exit list have 
EQCs above risk-based or extrapolated levels. Some of these 
constituents, such as Beryllium and Arsenic, are fairly prevalent. For 
less prevalent constituents, EPA has the same concerns about limiting 
exit for wastes managed in centralized wastewater treatment systems 
that it described above in the section on extrapolated risk levels. 
Further, this approach would overregulate wastes where constituents 
were in fact below risk levels. EPA prefers options which would not 
prohibit all wastes with these constituents from exiting.
    The most promising alternative EPA found was setting exit levels 
for these constituents at EQC levels, and also requiring all wastes 
containing these constituents to comply with LDR treatment standards, 
even where such waste are not destined for land disposal. This 
alternative offers the possibility of additional risk reductions and, 
therefore, reduces the possibility that wastes posing significant 
threats will escape Subtitle C control.
    EPA is unable to characterize the amount of additional risk 
reduction for a number of reasons. First, as explained in more detail 
in the Minimize Threat section of the preamble, compliance with LDRs 
already will be required after exit before land disposal for all wastes 
(except those that are below exit levels at their point of generation). 
The LDR requirement for constituents with EQC exit levels may provide 
additional risk reduction, even for those constituents that are not 
managed in land disposal units. EPA currently does not know how 
frequently nonhazardous wastes are burned as fuel, incinerated, or 
otherwise managed outside of land disposal.
    Additionally, the Universal Treatment Standards (UTS) for 
nonwastewaters, were developed based on similar analytical chemistry 
considerations of detection limits. The majority of the UTS limits for 
nonwastewaters were based, however, on analysis of residuals from the 
treatment of what EPA determined to be the most difficult to treat 
wastes and, as a result, this often represented the most difficult to 
analyze treated matrix (i.e., higher detection limits than those 
represented by the EQCs). The majority of the UTS limits for 
wastewaters, on the other hand, were not developed based on limits of 
detection but rather they were based on analysis of treated effluents 
regulated under EPA's National Pollution Discharge Elimination System 
(NPDES).
    LDR requirements for all wastes subject to the UTS would be equal 
to or higher than the EQC exit levels themselves. However, for wastes 
subject to treatment standards based on application of specified 
treatment methods under Sec. 268.40, extending LDR requirements may 
provide additional risk reduction.
    EPA believes that the combined approach of requiring non-detection 
at EQC levels and compliance with LDR standards for all waste streams, 
regardless of whether or not the waste will be land disposal, offers a 
reasonable balance between the goals of reducing overregulation and 
ensuring that wastes with significant risks remain subject to Subtitle 
C. EPA, however, requests comment on all of the alternatives described 
above. EPA also requests comment on the option of basing exit levels 
for these constituents on EQCs alone and relying on continued, 
independent applicability of LDR requirements for wastes that exit and 
are destined for land disposal.
3. Exemption for Constituents Without EQCs
    There are several constituents covered in today's notice for which 
EQCs could not be developed. The universe of these constituents 
includes 78 constituents, most of which are not widely prevalent in 
wastes. Most are also found only in P and U listed wastes. These 
constituents are listed in table B to appendix X without associated 
exemption levels. The background document Background Document to 
Support the Development of Exemption 

[[Page 66379]]
Quantitation Criteria (EQCs) and Description of Analytical Methods 
under the Waste Exit Rule explains why EQCs could not be created.
    EPA is proposing that wastes containing these constituents (i.e., 
where an applicant has not documented that these constituents are not 
present--see section VIII.A.1.b.,) may remain eligible for an exemption 
under today's proposed rule by complying fully with LDR treatment 
standards applicable to the waste, as codified in 40 CFR part 268, 
regardless of whether the waste is to be land disposed. The Agency 
believes that any potential risks posed by these constituents are 
likely to be further reduced by applying LDR standards from part 268 to 
the waste, before the waste may be exempt, regardless of whether or not 
the waste is destined for land disposal. The Agency asks for comment on 
this approach.
    An alternative approach would be to allow wastes with these 
constituents to exit without additional LDR obligations, but relying on 
continued, independent applicability of LDR treatment requirements to 
wastes destined for land disposal only. Another approach would be to 
prohibit wastes containing these constituents from being eligible for 
exemption under today's proposed rule. An additional approach would be 
that these constituents could be deleted from the exit table. The 
Agency requests comment on each of these alternatives.
    EPA is not willing to propose to use LDR standards as exit levels 
for any other group of constituents. The technology-based LDR standards 
are not based on any risk assessment. A comparison of these standards 
with the multipathway risk levels that EPA produced shows that the LDR 
standards are sometimes more stringent and sometimes less stringent 
than risk-based levels. EPA believes that it is more prudent to base 
exit levels on risk assessment where possible because this better 
assures protection of human health and the environment. EPA views use 
of the LDR standards as the option of least preference, but necessary 
for exit for this group of constituents. EPA is willing to consider it 
only where there is no alternative to prohibiting a constituent from 
being eligible for exit.

V. Presentation of Exit Levels

    Today's proposed exemption criteria involves setting exemption 
levels for toxicants in listed waste, and in some cases requiring 
additional compliance with the requirements set forth at 40 CFR part 
268. To exit Subtitle C regulation as a listed hazardous waste, all the 
hazardous constituents listed in appendix X of part 261 would be 
required to be in concentrations less than or equal to the numeric exit 
levels and when specified, the waste would have to meet the applicable 
requirements at 40 CFR part 268. Appendix C to the preamble presents 
constituents, distinguishes between modeled and extrapolated 
constituents, and includes EQCs for each constituent.

A. Constituents With Modeled or Extrapolated Risk-Based Exit Levels

    The Table A of proposed appendix X to part 261 presents exit levels 
for constituents with modeled or extrapolated risk-based levels which 
can be reliably quantified. See section IV.H. for a description of how 
this was determined. Listed hazardous waste would be required to 
contain concentrations at or below the specified exit levels to be 
eligible to be exempted from Subtitle C requirements other than LDR. In 
some cases we are proposing to change the land disposal restriction 
requirements at 40 CFR part 268 as well. A totals analysis would be 
required for both wastewaters and nonwastewaters to show that the 
constituent does not exist in the wastestream at levels above the 
exemption level.
    For nonwastewaters, the Agency is also proposing that generators 
either use the TCLP test or a calculational screen to measure or 
calculate constituents' leachate from wastes. If the TCLP test shows 
leachate concentration in the waste is below the leach exit level, the 
waste would be considered to not pose a hazard to groundwater.
    The Agency has in the past experienced difficulty in using the TCLP 
test for some types of waste. The Agency solicits comment on how to 
consider oily wastes and other wastes that are difficult to filter in 
the TCLP test or whose impact on groundwater is believed to be 
underestimated by the TCLP (such as materials subject to non-aqueous 
phase transport). Comment on alternative tests for these wastes, as 
well as comment on how to define such wastes for regulatory purposes is 
sought. A more complete discussion of oily waste can be found in 
VIII.A.1.a.iv.
    Table A of appendix X of 40 CFR part 261 presents results of two 
alternatives for establishing the exit levels. These alternatives 
differ only in the benchmark used to calculate the modeled risk-based 
levels. For certain constituents there exists both a risk-based 
toxicity benchmark and a maximum concentration level (MCL) established 
under the Safe Drinking Water Act (SDWA). These numbers may differ 
because the MCLs are established using some non-risk considerations 
such as the cost of treatment and the availability of technology and 
consider exposure contributions from other sources for non-carcinogens. 
See section IV.D. of today's proposal for a complete discussion of 
toxicity benchmarks and MCLs.

B. Constituents With Quantitation-Based Exit Levels; Table B to 
Appendix X

    Table B of proposed appendix X to part 261 presents quantitation-
based exit levels for constituents with methods that cannot reliably 
quantify the modeled or extrapolated risk-based levels. All exit levels 
on Table B of appendix X to 40 CFR part 261 are based on EQCs. (See 
section IV.I.) Wastes containing any of these constituents must also 
comply with the applicable treatment standards set forth at 40 CFR part 
268, the Land Disposal Restrictions (LDR) in order to meet today's 
proposed exemption, regardless of whether or not the waste is to be 
land disposed.
    Some constituents on Table B of appendix X of 40 CFR part 261 do 
not have associated exit levels. Waste with these constituents may exit 
only after complying with the LDR treatment standards for the waste. 
(See section IV.I.2.b.)

C. How To Read the Exit Level Tables

    For a waste to be eligible to exit Subtitle C under the exit 
proposed in today's rulemaking, every constituent in the waste must be 
below its exit level. Proposed appendix X of 40 CFR part 261, Tables A 
and B are the exit constituents and the exit levels. The following is a 
description of how to read the tables.
     The constituent list is derived from constituents listed 
in appendix VII, Basis for Listing Hazardous Waste; Appendix VIII, 
Hazardous Constituents; and appendix IX of part 264, the Ground-Water 
Monitoring List. (See section IV.C.)
     Table A represents constituents and their risk exit 
values--where the risk values can be measured analytically. (See 
sections IV.E., and IV.I.)
     Table B represents constituents with quantitation limits 
(EQCs) as exit levels--where the constituent cannot be measured at the 
modeled or extrapolated risk value. An additional condition of exit, 
compliance with treatment standards in 40 CFR part 268, exists for any 
waste becoming exempt under today's rulemaking by using a constituent 
exit level on Table B. (See section IV.I.2.b.)
     There will be overlap for some constituents between Tables 
A & B. For 

[[Page 66380]]
example, the wastewater exit level for a constituent may be on Table A, 
whereas the nonwastewater exit level may be on Table B.
     Where an exit level does not exist on Table A or B for a 
particular constituent, the waste need not be tested for that 
constituent. For example, some constituents that are hydrolyzers have 
exit levels for nonwastewaters, but not for wastewaters. A complete 
discussion of deletions to the master constituent list can be found in 
section IV.C.
    The tables' columns:
     Columns 1 and 2 are the CAS numbers & constituent names.
     There are two proposed options for the development of 
today's proposed exit levels. Option 1 is the option whereby Maximum 
Contaminant Levels (MCLs) from the Drinking Water program are used as 
an acceptable toxicity exposure for human drinking water exposure and 
toxicity benchmarks are used for other exposures. Option 2 is the 
option whereby toxicity benchmarks are used as acceptable exposure 
levels for all exposures. A more complete discussion of these two 
options is found in section IV.D. of today's proposed rule. The effect 
of co-proposing these two options is that there are two independent 
sets of proposed exit levels.

--Columns 3, 4, and 5 represent the exit levels that were derived by 
using an MCL benchmark for drinking water ingestion & using toxicity 
benchmarks for all other routes of exposure.
--Columns 6, 7, and 8 represent the exit levels that were derived by 
using toxicity benchmarks for all routes of exposure.

     The definitions of wastewater and nonwastewater are 
discussed in VIII.A.1.a.ii.
     Columns 3 & 6 represent wastewater exit values. If a 
generator determines he/she has a wastewater, if each constituent in 
the waste meets these wastewater exit levels, it is eligible for 
exemption.

--Values in columns 3 & 6 were derived from the most limiting of non-
groundwater-ecological receptor, non-groundwater-human receptor, and 
groundwater pathway values from surface impoundments and tanks (the 
risk assessment's wastewater units).

     Columns (4 and 5) and (7 and 8) represent nonwastewater 
exit values. If a generator determines he/she has a non-wastewater, if 
each constituent in the waste meets both of these nonwastewater values, 
it is eligible for exemption. The totals level must be met by a totals 
analysis. The leach level must be met by a TCLP test or the 
calculational screen.

--Values in columns 4 & 7 were derived from the most limiting of the 
non-groundwater-ecological receptor and non-groundwater-human receptor 
pathway values from land application units, ash monofills, and waste 
piles (the risk assessment's nonwastewater units).
--Values in columns 5 & 8 were derived from the most limiting of the 
groundwater pathway values from land application units, landfills, and 
waste piles (the risk assessment's nonwastewater units).

VI. Minimize Threat Levels

A. Background

1. Summary of the Hazardous and Solid Waste Amendments of 1984
    The Hazardous and Solid Waste Amendments (HSWA), enacted on 
November 8, 1984, allow hazardous wastes to be land disposed of only if 
they satisfy either of two conditions: (1) They can either be treated 
or otherwise satisfy the requirements of section 3004(m), which 
requires EPA to set levels or methods of treatment, if any, which 
substantially diminish the toxicity of the water or substantially 
reduce the likelihood of migration of hazardous constituents from the 
water so that short term and long term threats to human health and the 
environment are minimized; or (2) they can be land disposed in units 
satisfying the so-called no migration standards in sections 3004(d)(1), 
(e)(1), and (g)(5). Land disposal includes any placement of hazardous 
waste in a landfill, surface impoundment, water pile, injection well, 
land treatment facility, salt dome formation, underground mine or cave. 
See RCRA section 3004(k).
    EPA was required to promulgate land disposal prohibitions and 
treatments standards by May 8, 1990 for all wastes that were either 
listed or identified hazardous at the time of the 1984 amendments, a 
task EPA completed within the statutory time frames. See RCRA section 
3004(d), (e), and (g). EPA is also required to promulgate prohibitions 
and treatment standards for wastes identified or listed after the date 
of the 1984 amendments within six months after the listing or 
identification takes effect. See RCRA section 3004(g)(4).
    The land disposal restrictions are effective on promulgation. See 
RCRA section 3004(h)(1). However, the Administrator may grant a 
national capacity variance from the effective date and establish a 
later effective date (not to exceed two years) based on the earliest 
date on which adequate alternative treatment, recovery, or disposal 
capacity that protects human health and the environment will be 
available. (RCRA section 3004(h)(2).) The Administrator may also grant 
a case-by-case extension of the effective date for up to one year, 
renewable once for up to one additional year when an applicant(s) 
successfully makes certain demonstrations. (RCRA section 3004(h)(3).) 
See 55 FR 22526 (June 1, 1990) for a more detailed discussion on 
national capacity variances and case-by-case extensions.
    As explained in the legislative history, the purpose of the land 
disposal restrictions is to reduce the risks associated with land 
disposal. Congress also intended the restrictions to reduce reliance on 
land disposal and promote waste minimization since land disposal was 
its least favored method of managing hazardous wastes.
2. EPA's Interpretation of Standard for Treatment Requirements
    The heart of the LDRs are the standards for treatment prior to land 
disposal, which must meet the statutory requirement to ``substantially 
diminish the toxicity of the water or substantially reduce the toxicity 
of the waste so that short term and long term threats to human health 
and the environment are minimized.'' RCRA Section 3004(m): EPA's 
interpretation of this ``minimize threat'' requirement has evolved 
through a long series of rulemakings.
    When EPA proposed its first set of LDR treatment standards it took 
the position that the most effective way to minimize threats was to 
base standards on the capabilities of generally available treatment 
technologies. (51 FR 16011 (January 14, 1986).) To avoid unnecessary 
treatment, however, EPA also proposed to ``cap'' the technology based 
standards with risk-based screening levels based on human health 
toxicity thresholds for individual hazardous constituents and modeling 
of the groundwater route for exposure. (51 FR 16011-13.)
    In the final rule EPA promulgated only the technology based 
standards. EPA explained that although it believed it had authority to 
promulgate risk-based standards, it was not promulgating the proposed 
risk-based caps because of extensive comments raising concerns about 
the scientific uncertainties of risk analysis. (52 FR 40578 (November 
7, 1986).) Industry challenged the final standards, claiming that they 
required treatment to concentrations below ``minimize threat'' levels. 
On review, the Court held that section 3004(m) authorized both 

[[Page 66381]]
technology based and risk-based standards, but remanded the rule to EPA 
for a fuller explanation of its decision to rely on technology-based 
standards alone. (Hazardous Waste Treatment Council v. EPA, 886 F. 2d 
355 (D.C. Circ. 1989). (``HWTC III'').) The court also held that EPA 
was not obligated to adopt either the RCRA characteristic test levels 
or the Safe Drinking Water Act Maximum Contaminant levels (MCLs) as 
``minimize threat'' levels because neither ``purports to establish a 
level at which safety is assured or `threats to human health and the 
environment are minimized'.'' (886 F. 2d at 363.)
    In its response to the remand, EPA stated that the best way to 
fulfill the requirements of section 3004(m) would be to ensure that no 
technology-based treatment standard required treatment of hazardous 
waste containing levels of hazardous constituents posing insignificant 
risks. (55 FR 6641 (Feb. 26, 1990).) EPA, however, explained that it 
was not yet able to promulgate such levels. EPA believed that it lacked 
a reliable predictive model for ground- water exposure, needed to 
assess exposure scenarios for air pathways, needed to consider impacts 
on ecological receptors, needed to develop additional analytic methods 
for hazardous constituents, and needed to develop an approach for 
constituents with threshold effect levels lower than detection limits. 
(Id. at 6642.)
    In the same notice, EPA noted that the ``minimize threat'' language 
of section 3004(m) could reasonably be interpreted to require more 
protection than the ``normal subtitle C command that standards be those 
necessary to protect human health and the environment.'' (Id. at 6641.) 
EPA found that the many portions of the 1984 amendments stressing the 
inherent uncertainties of land disposal buttressed this interpretation. 
See, e.g., RCRA sections 1002(b)(7), 3004(d)(1)(A), 3004(e)(i)(A), 
3004(g)(5). EPA also found support in the legislative history. For 
example, the Senate amendment containing the ``minimize threat'' 
standards replaced a committee bill that only would have required 
treatment to be ``protective of human health and the environment.'' See 
S. 757, section 3004(b)(7), printed at S. Pep. No. 284, 98th Cong., 2nd 
Session 86. Further, EPA noted that the ``no threat'' levels it had 
been using in site-specific and waste stream specific contexts, such as 
clean closures, delistings, and no-migration petitions, would not 
necessarily be appropriate for generally applicable standards required 
to minimize threats to health and the environment. (55 FR 6641, note 
1.)
    At the same time, EPA took the position that section 30004(m) does 
not require the elimination of every conceivable threat posed by land 
disposal of hazardous waste, citing a statement by Senator Chafee that 
``[i]t is not intended that every waste receive repetitive levels of 
treatment, nor must all inorganic constituents be reclaimed.'' 130 
Cong. Rec. S.9179 (daily ed., July 25, 1984). (55 FR 6641, note 1.) 
Clearly EPA did not interpret the minimize threat language to require 
the elimination of all threats.
    Today, the Agency is proposing to re-evaluate the basis for some of 
the existing performance standards established for listed wastes. Since 
EPA's response to the HWTC III remand in 1990, the state-of-the-art in 
making quantitative determinations of risk has advanced and available 
methods have improved significantly. In addition, the increased 
sensitivity of analytical methods has lowered achievable detection 
limits, better bioassays exist than in the past, and more extensive 
biological data is available for extrapolation. As a result, the 
universe of available health-based and ecological data has grown 
significantly, and the reliability of this information has improved. 
The Agency now believes that these data can be used to establish levels 
that minimize threats to human health and the environment.

B. Risk Assessment and Minimize Threat Levels

1. Rationale
a. Overview
    Today the Agency is proposing to establish risk-based LDR treatment 
requirements for some of the hazardous constituents for which exit 
levels are being proposed. These risk-based LDR requirements will 
minimize the short-term and long-term threats to human health and the 
environment posed by the hazardous waste constituents. The risk-based 
LDR levels (or ``minimize threat'' levels) would have the effect of 
capping, or limiting, treatment of those waste constituents where the 
current technology-based UTS standards require lower concentrations. 
EPA also hoped to propose most of these constituent-specific levels as 
``minimize threat'' levels under section 3004(m) of RCRA that would cap 
current technology-based treatment standards under at these levels the 
LDR program. However, EPA is proposing ``minimize threat'' levels only 
for those constituents that were evaluated under the multipathway risk 
analysis and are not capped by quantitation (EQC) limitations. EPA is 
proposing to promulgate such levels as replacements for the 
constituent-specific treatment levels in the LDR Universal Treatment 
Standards (UTS). (As explained in more detail in Section VI, EPA is not 
proposing to cap any LDR standards requiring the use of specified 
technologies.) As shown on Table 1, Sec. 268.60, EPA is proposing 
``minimize threat'' levels to cap UTS treatment requirements for either 
the wastewater or nonwastewater (or both) for approximately 70 
wastewater constituents and 90 nonwastewater constituents.
    EPA, however, is not proposing that any extrapolated levels serve 
as ``minimize threat'' levels for LDR purposes. EPA does not have as 
much confidence that this alternative methodology provides enough 
information on risks to human health and the environment to enable EPA 
to determine that risks have been minimized. Similarly, EPA is not 
proposing that any levels based on quantitation limits serve as 
``minimize threat'' levels. Such levels are not based on any analysis 
of risks to human health and the environment. In fact, as explained 
above, EPA is proposing to require compliance with technology-based LDR 
standards for all wastes which contain such constituents.
    If a claimant finds that all constituents in a waste are below exit 
levels at the waste's point of generation and if the claimant meets all 
of the requirements for filing an exit claim, EPA will not require 
compliance with the LDR treatment standards for the waste. EPA will 
take the position that such as waste never became subject to subtitle C 
regulations, so that LDR standards never applied to the waste. EPA is 
proposing to take this position for all exit levels, regardless of 
whether they were generated by the multipathway analysis, the 
extrapolation method, or EQC limitations. For further explanation, see 
section VI.D.
    EPA, however, is proposing that all listed wastes which as 
generated contain constituents exceeding exit levels must meet LDR 
requirements (current or as modified by this proposal), even if the 
waste subsequently becomes exempt from hazardous waste regulation under 
this rule. This requirement resembles EPA's current rules for ``de-
characterized'' wastes, which must meet LDR requirements even after 
they cease to exhibit the hazardous characteristic that made them 
subject to Subtitle C in the first place. 

[[Page 66382]]

b. ``Minimize Threat'' requirement of Section 3004(m)
    EPA continues to believe that the minimize threat language of 
section 3004(m) does not require the elimination of every conceivable 
threat posed by land disposal of a hazardous waste. The legislative 
history of LDR indicates that Congress did not intend to require wastes 
to undergo repetitive or ultimate levels of treatment. Rather, Congress 
wanted to require use of effective, but widely available treatment 
technologies. See 130 Cong. Rec. S 9178 (daily ed. July 25, 1984) 
(statement of Senator Chafee introducing the amendment that became 
section 3004(m).)). Requiring elimination of all conceivable threats 
would almost certainly require use of the most effective treatment 
methods available, and this appears to conflict with Congresses' 
treatment goals. Moreover, although the DC Circuit has cited the 
dictionary definition of ``minimize'' to uphold technology-based 
treatment standards below EPA standards such as MCLs and TC levels, EPA 
does not believe that the court meant that EPA literally must reduce 
threats to the maximum extent possible. (See Hazardous Waste Treatment 
Council III, 886 F.2d at 361; Chemical Waste Management II, 976 F 2d. 
at 14.) EPA notes that the court indicated that risk-based treatment 
standards would satisfy section 30004(m). Hazardous Waste Treatment 
Council III, 866 F.2d at 364-65. Further, in his concurring opinion, 
Judge Silberman stated that Congress would allow EPA to exercise 
reasonable amounts of discretion in determining the level of risk 
reduction needed to meet the minimize threat requirement. Id. at 372.
    The Agency believes that today's exit concentrations can serve as 
risk-based land disposal restriction levels for several reasons. First, 
the risk assessment, described in Section IV of today's proposal, 
significantly expands beyond the scope of past Agency risk assessment 
for wastes and waste constituents. Where adequate data are available, 
the analysis can evaluate the potential for waste constituent migration 
through almost all significant environmental fate and transport 
pathways leading to exposure for human and ecological receptors. As 
explained in more detail below, the Agency is also relying on 
reasonable conservative risk targets for both humans and ecological 
receptors in developing this risk assessment. The Agency believes that 
the proposed exit levels represent levels below which further treatment 
would not be needed to minimize threats to human health and the 
environment.
c. Scope of Risk Assessment
    The broad scope of the risk analysis is a critical factor in the 
Agency's conclusion that proposed exit levels minimize both short term 
and long-term threats to human health and the environment, for those 
constituents where data are relatively complete.
    The risk analysis evaluates all of the most common non-Subtitle C 
disposal options available to waste generators and treaters. These 
include disposal in landfills/monofills and by land farming, and 
management in surface impoundments, tanks and waste piles. The risk 
analysis assumes no minimum level of regulation of these facilities, 
and relies on available data to characterize them. As described in 
detail in Section IV and in the risk analysis report (EPA 1995), EPA 
modeled each disposal alternative using median values for most inputs, 
and high-end or conservative values for the two fate and transport and 
two exposure parameters for which the modeling outcome is most 
sensitive. The Agency believes that the modeling will also protect 
against exposures from similar disposal alternatives not specifically 
modeled.
    The risk analysis evaluates the movement of waste constituents from 
each of these disposal options through numerous environmental fate and 
transport pathways. These include pathways involving volatiles and 
respirable (PM10) particulates, particulate deposition on soil and 
plant surfaces, vapor phase diffusion into surface water and plants, 
and surface run-off and soil erosion. Many of these pathways can result 
in waste constituent movement through the food-chains. Therefore, human 
exposures resulting from these fate and transport pathways include 
inhalation, soil or groundwater ingestion, and dermal contact, as well 
as exposure through consumption of contaminated foods such as fish, 
beef or vegetables.
    EPA screened all multipathway constituents for potential to pose 
threats to ecological receptors. For 45 constituents, EPA 
quantitatively assessed likely risk to selected ecological receptors. 
Risks to both fresh water aquatic and terrestrial organisms were 
evaluated, representing different trophic levels and feeding habits of 
the ecosystem. Fish, daphnids, and benthic organisms, mammals, birds, 
plants, and soil organisms (nematodes, insects, etc.) were evaluated. 
The sustainability of the ecosystem and reproducing populations within 
the aquatic and terrestrial ecosystems was selected as an assessment 
endpoint, as described in Section IV of this Notice and in detail in 
Chapter 3 of the risk analysis support document (EPA 1995).
    In addition, as part of this overall risk assessment effort, the 
Agency has reviewed and reevaluated its modeling of waste and waste 
constituent movement through groundwater. As described in Section IV 
above, this responds to comments by interested parties on the original 
HWIR proposal, as well as incorporates additional data submitted to the 
Agency (API data base), and updated modeling of leaching from wastes 
(new HELP model; get Cite).
    In evaluating groundwater, the Agency examined both wells located 
on the landfill edge and closest wells anywhere down-gradient. Also, 
both finite source type and infinite-source type constituents (which 
behave as though there is an infinite supply of the constituent in the 
landfill, and will continue to leach forever) were evaluated. For 
finite source type constituents, the available constituent was not 
apportioned over the groundwater and other pathways, i.e., groundwater 
was modeled separately. Adsorption to soil and degradation of waste 
constituents (but not biodegradation) is modeled, and the toxicity of 
constituent daughter products (either more or less toxic than the 
parent compounds) is included. (There is a biodegradation module to the 
model; however, data to run that module for national conditions are not 
adequate at this time, although data were available for some sites. The 
Agency will continue to evaluate biodegradation data as they become 
available, and assess in the future whether national biodegradation 
estimates can be defensibly made). Leaching and groundwater migration 
from disposal in unregulated industrial landfills, surface 
impoundments, and waste piles have been modeled.
    In evaluating the results of this series of groundwater modeling 
exercises, the Agency selected the approximate 90th percentile from a 
distribution of wells closest to modelled sites. This means that there 
is about a 90% probability that the drinking water well closest to the 
landfill would be protected at the target concentration (MCL or HBN). 
All wells more distant would be protected to a greater extent.
    As described in section VI.E. above, the Agency then reviewed the 
risk assessment for groundwater and the pathways for each constituent, 
and selected as the exit level the concentration, back-calculated to 
the waste, from the most limiting (or highest risk) pathway. By using 
the most 

[[Page 66383]]
limiting pathway as the basis for the risk criterion, the Agency 
believes it has accounted for all significant risks resulting from 
disposal and management of the waste outside of Subtitle C.
    The agency believes it is also important to identify and discuss 
some of the limitations of the risk assessment, especially as they 
relate to determining whether short term and long-term threats to human 
health and the environment have been minimized.
    The analysis does not account for additivity of risk for exposure 
to multiple constituents. Evaluation of risk additivity can be a 
complex analysis when even a few constituents are included. In the case 
of multiple waste constituents, potentially occurring in one or more 
waste streams that might be considered for exit, the complexity of 
conducting and analysis of additivity of risk quickly becomes 
overwhelming. However, EPA believes it will often be the case that one 
constituent typically drives determinations of whether waste streams 
exit and additivity would often make little difference with respect to 
the calculated exit levels.
    Exposures to the same constituent from several pathways also are 
not added together, even though the risk analysis does apportion the 
available quantity of waste constituents over the different pathways 
evaluated. Again, EPA believes that often one result (in this case, one 
pathway) would contribute most of the risk and little would be gained 
from adding across pathways. EPA requests comment on this issue.
    Data also were not available for all human exposure routes for all 
constituents, although data for high-risk pathways were usually 
available. Nonetheless, the Agency believes the exit levels can be 
considered to represent levels that minimize threats to human health 
and the environment because of the comprehensive evaluation of possible 
exposure routes, consideration of both human and ecologic risk, 
selection of the most restrictive pathway overall, and the relatively 
conservative risk target, 10-6, used in setting the exit levels 
derived from cancer risk estimates.
    As mentioned above, EPA conducted a screening analysis to identify 
47 high priority constituents for ecological assessment. EPA did not 
model the ecological impacts for 36 additional constituents that 
displayed one characteristic indicating potential ecological impacts. 
EPA is proposing to set minimize threat levels for 19 of these 
constituents.
    EPA believes that it has adequately assured that the caps to BDAT 
treatment standards proposed today minimize threats to the environment. 
The specific ecological risk assessment conducted for 45 constituents 
(19 of which have minimize threat levels under this proposal) is the 
most extensive EPA has ever conducted under the RCRA program to date. 
EPA did not find threshold effects data for all seven groups of 
ecological receptors for any constituent evaluated for ecological 
risks. Rather, EPA typically had benchmarks for three to five groups. 
Nevertheless, its consideration of a broad range of species and use of 
reasonably conservative endpoints ensures that threats to ecological 
receptors are minimized.
    With regard to chemicals that did not undergo this detailed 
assessment, EPA has conducted an extensive review of risks to human 
health, including a thorough review of risks posed by indirect pathways 
and risks posed by constituents that bioaccumulate in plants and 
animals consumed by humans. (Bioaccumulation is a key concern for 
protection of many ecological species.) EPA believes that it is 
reasonable to assume that the exit levels identified by this analysis 
also minimize threats to ecological receptors unless it has some 
definite data indicating that additional protection is warranted. 
Reliance on these levels is particularly appropriate for those 
chemicals that did not display one of EPA's ecological screening 
characteristics. EPA finds it also appropriate for the 15 ``minimize 
threat'' chemicals which exhibited one ecological screening 
characteristic. EPA acknowledges that conducting a specific assessment 
of ecological risks for these 15 constituents would have provided 
additional assurance that threat to ecological receptors were 
minimized. EPA solicits comment on the option of declining to set 
minimize threat levels for these 15 constituents until it can complete 
an ecological assessment for them.
d. Risk Targets Minimize Threats
    The Agency believes that the risk targets used in the risk analysis 
to back calculate to waste concentrations minimize threats to human 
health and the environment. For cancer risks to human, a risk target of 
one in one million, over a lifetime is the risk target. For non-
carcinogens, a hazard quotient (HQ) based on a reference dose or other 
comparable value from the literature could not exceed one (hazard 
quotient (HQ)=1). Reference doses or comparable values are based on 
studies of toxicity and no-effect levels in test animals and 
extrapolated, using safety factors, to humans. For ecological 
receptors, population effects inferred from individual effects and 
effects on a substantial number of both aquatic and terrestrial species 
were evaluated.
    Other risk targets may be considered in establishing minimize 
threat levels. The Agency solicits comment on whether apportionment of 
the RfD ought to be used in establishing minimize threat levels (i.e., 
HQ<1). The Agency uses 20% of the Rfd in setting drinking water 
standards; a similar approach might be appropriate in establishing 
minimize threat levels and in establishing exit levels. EPA requests 
comment on this issue.
2. Public Policy Considerations
    Finally, the Agency believes that it represents good public policy 
to reduce or eliminate unneeded or duplicative regulatory requirements. 
In this case, the Agency believes that for the initial list of 
constituents listed in Table 1 of 40 CFR 268.60, treatment to the UTS/
LDR standard is no longer required beyond waste constituent 
concentrations where risks to human health and the environment are 
insignificant. Because there is no purpose in terms of protecting human 
health and the environment for retaining the more stringent LDR 
requirements, the Agency is proposing to revise them to the risk-based 
levels. This would reduce the overall number of different and distinct 
regulatory requirements on waste generators and treaters, would 
rationalize the RCRA regulations, and will provide significant 
pollution prevention opportunities and incentives. Waste generators 
would have only one target level to direct their pollution prevention 
effort toward. If generators met the LDR/exit levels, the waste would 
not be considered hazardous, and no additional treatment would be 
required before disposal in a subtitle D facility. Where waste 
continues to exceed one or more exit levels after LDR requirements are 
met, subtitle C disposal would be required.

C. Risk-based LDR Levels

1. List of Constituents and Minimize Threat Concentrations
    As was mentioned earlier in this section, only modeled 
constituents' risk-level results are eligible to serve as risk-based 
LDR levels meeting the statutory requirement of minimize threat. In 
addition, minimize threat levels are only proposed for those 
constituents where the risk level is higher (less stringent) than the 
associated 

[[Page 66384]]
technology-based treatment standard in Sec. 268.40 or the UTS level in 
Sec. 268.48.
    First, the Agency repeats that it is not proposing to set any 
alternative risk-based LDR standards expressed as specified 
technologies (rather than constituent concentrations.) Consequently, 
the option of complying with minimize threat levels in lieu of levels 
specified in part 268 will be available only for wastes with treatment 
standards expressed as constituent concentrations. This includes both 
wastes subject to waste-specific treatment requirements under the table 
to Sec. 268.40 and wastes subject to the Universal Treatment Standard 
levels in the table to Sec. 268.48
    The Agency proposes that for purposes of establishing nonwastewater 
and wastewater minimize threat values for wastes with BDAT treatment 
standards expressed as constituent concentrations, the levels proposed 
would utilize the LDR definitions of nonwastewater and wastewater from 
40 CFR 268.2(d) and (f). Therefore, any exit levels that are considered 
nonwastewater for purposes of exit will also be considered 
nonwastewater for purposes of minimize threat. Likewise, wastewater 
exit levels will be considered wastewater LDR levels. The Agency 
believes that consistent definitions of nonwastewater and wastewater is 
the only practical means to establish minimize threat levels. The 
Agency realizes, however, that the modeling and subsequent development 
of exit levels for today's proposed exit did not use the part 268 
definition of nonwastewater and wastewater. (A complete discussion of 
this may be found in section VIII.A.1.a.ii.) The effect of this would 
be that some wastes that would be defined as wastewaters under today's 
proposed exit scheme would be considered LDR non-wastewaters. The 
Agency requests comment on whether the definition in Part 268 should be 
adopted for purposes of establishing minimize threat levels.
    The Agency compared the exit levels to the current LDR treatment 
levels to determine whether a constituent's risk level should be 
proposed as a minimize threat level. For wastewater values, the LDR 
wastewater value was directly compared to the wastewater exit value. 
Where the UTS nonwastewater level is a total level, the comparison was 
made to the nonwastewater totals exit level. Where the LDR 
nonwastewater level is a leach level, the comparison was made to the 
nonwastewater leach exit level. However, for the reasons explained 
below, the nonwastewater minimize threat level would contain both a 
leach level and a totals level. For both wastewater and nonwastewater, 
where the most comparable exit level is higher (less stringent) than 
the current LDR level, the constituent's risk level is proposed as an 
optional minimize threat level. The Agency requests comment on this 
approach to determining which exit levels are higher than current LDR 
levels.
    The Agency is proposing that testing requirements when using 
minimize threat levels would be consistent with the current LDR testing 
requirements found in Sec. 268.7. The Agency proposes that if a 
claimant wishes to meet LDR requirements by complying with a minimize 
threat level, the claimant must meet the minimize threat levels with a 
totals analysis, and where specified, the waste must meet the leach 
level with a leachate analysis. The Agency believes that a totals 
analysis is preferable to a leach analysis for establishing minimize 
threat levels, as it more directly pertains to all pathways, not only 
the groundwater pathway.
    Today's proposed exit levels for nonwastewaters consist of two risk 
levels for each constituent. The totals (mg/kg) nonwastewater risk 
level is the result of the most limiting non-groundwater pathway. The 
leach (mg/L) nonwastewater risk level is the result of the most 
limiting groundwater pathway. The Agency believes it would be 
preferable to have one exit level, but the groundwater model results 
are a leach (mg/l), whereas the results from the multipathway analysis 
are a totals (mg/kg), and the science to extrapolate from a leach to 
totals is highly variable. Using only the leach or only the total risk 
level would reflect only a portion of the risks presented by the waste. 
A waste must meet both of these limits before it minimizes threats to 
human health and the environment. Consequently, EPA is proposing to 
include both levels in the minimize threat standards for 
nonwastewaters. The Agency proposes to allow generators to either use a 
calculational screen or perform the TCLP to make a determination that 
constituent concentrations do not exceed nonwastewater leach minimize 
threat levels. A full discussion and explanation of the calculational 
screen can be found in section VIII.A.1.a.iii. of today's proposal.
    Because extrapolating from a leach to a total varies with each 
constituent and is not easily measured, EPA has not directly compared 
both of the minimize threat levels with the LDR standard. The Agency 
requests data on specific constituents where the second, less easily-
compared nonwastewater minimize threat level may be harder to achieve 
than the current LDR standard. If such results occur, waste handlers 
will not be required to use the new minimize threat levels. The levels 
in the tables to Sec. 268.40 and Sec. 268.48 will continue to satisfy 
LDR requirements as they always have. The minimize threat levels will 
be located in Table 1 of Sec. 268.60, are optional, and are intended to 
be used to provide treatment relief. The Agency believes that minimize 
threat levels will only be used where they are less stringent than 
current LDR levels. The Agency requests comment on the proposed 
revisions to part 268 with respect to minimize threat levels.
    Table D-1 of appendix D to the preamble presents for comparison 
current LDR UTS standards and proposed minimize threat levels. The 
Agency is proposing that for the constituents listed below, the risk 
levels may substitute for current UTS treatment levels in 40 CFR 268.48 
or for treatment standards for these constituents in 40 CFR 268.40. A 
table of the proposed minimize threat levels can be found at proposed 
40 CFR 268.60 subpart F in the regulatory text following this preamble.
2. Constituents for Which Exit Levels Are Not Minimize Threat Levels
    As an alternative to the approach described in C.1 above, the 
Agency solicits comment on the background data underlying the risk 
evaluations for these constituents. The Agency believes, in general, 
that the constituents evaluated in the risk analysis have relatively 
complete assessments of risk. The Agency recognizes, however, that data 
quality and completeness can vary among constituents, even for those 
for which risk can be assessed. The Agency solicits comment on both 
general criteria for assessing completeness of data, and also specific 
constituents for which use as minimize threat levels to cap LDR 
requirements may be inappropriate.

D. Meeting LDR Requirements

1. Wastes Below Exit Levels as Generated
    EPA proposes that, if a generator samples a listed waste stream at 
its point of generation and analysis of the sample shows all 
constituents to be below exit levels, LDR requirements would not apply 
to the waste. EPA is proposing this result both for constituents with 
exit levels based on multipathway analysis (where, since exit levels 
can serve as LDR ``minimize threat'' levels that cap current treatment 
requirements, the LDR program will never require treatment to levels 
lower than exit levels) and constituents with 

[[Page 66385]]
exit levels based on extrapolation from the multipath analysis or 
quantitation levels (where, since EPA has not proposed to make exit 
levels into LDR minimize threat levels,the LDR programs may require 
treatment to levels lower than exit levels).
    To claim this relief generators would have to certify that they 
sampled their wastes at the point of generation. In the interim between 
sampling and receipt of analytical results, the generator would be 
required to manage the waste as hazardous. However, EPA would take the 
position that this brief period of Subtitle C regulation would not 
subject the waste to LDR requirements.
    EPA believes that position is consistent with its prior 
interpretations of LDR provisions and the D.C. Circuit's opinion in 
Chemical Waste Management II. At issue in that case was EPA's 
determination that LDR treatment standards apply to wastes that are 
characteristically hazardous at the point of generation but that 
subsequently cease to exhibit characteristics and become nonhazardous 
wastes. EPA took that position to ensure that characteristic wastes 
receive effective treatment. Without this requirement, for example, it 
would be possible to dilute characteristic wastes and evade LDR 
treatment requirements. The Court held that EPA must apply this 
interpretation consistently to characteristic wastes.
    It is not necessary, however, to follow this interpretation for 
wastes that are generated with all constituent concentrations below 
exit levels. EPA can reasonably distinguish between wastes that are 
below exit levels at the point of generation and wastes which achieved 
such levels at some subsequent time. Only wastes which exceed exit 
levels at the point of generation need continued LDR applicability to 
ensure that they reduce constituent concentration or constituent 
mobility by complying with LDR standards rather than using dilution or 
some other inferior form of treatment. A generator of wastes that meet 
exit levels as generated would not use waste treatment to evade LDR 
requirements. Rather, he or she might use waste minimization techniques 
to reduce concentration or mobility of constituents in the precursor to 
his waste.
    EPA notes that it is proposing to require listed wastes which 
exceed exit levels at the point of generation to meet LDR treatment 
requirements, even if the waste later meets exit levels. EPA believes 
that this requirement carries out the LDR requirements set out in the 
Third Third rule and the Chemical Waste decision.
    Finally, EPA notes that it would be possible to articulate 
alternative rationales for exempting from LDR requirements wastes which 
meet today's exit levels as generated. For exit levels based on 
extrapolations from the multipathway analysis, EPA could argue that 
extrapolated levels are LDR ``minimize threat'' levels. EPA, however, 
thinks protection of the environment is better served by refraining 
from such a step and requiring wastes which exceed such levels at the 
point of generation to meet current technology-based LDR standards. (As 
explained above, EPA is not entirely certain that these extrapolated 
levels actually minimize risks for all constituents.) For exit levels 
based on quantitation limits, imposing LDR requirements would not have 
any practical impact. LDR treatment standards are limited by the same 
quantitation limits proposed for this rule. Consequently, treatment 
standards for constituents limited by analytical capabilities are not 
lower than the exit levels.
2. Wastes Above Exit Levels as Generated
    Listed wastes that are above exit levels as generated would be 
required to be treated to the LDR standards in force at the time if 
they are placed on the land.

VII. Dilution

    The 1984 RCRA Amendments (HSWA) established a vigorous national 
policy for minimizing the generation of hazardous wastes. Section 1003 
of RCRA, as amended in 1984, established a national waste minimization 
policy stating that ``wherever feasible, the generation of hazardous 
waste is to be reduced or eliminated as expeditiously as possible''. 
The policy also cited the need to reduce the volume and toxicity of 
hazardous wastes which is nevertheless generated. Similarly, section 
3005(h) prescribed that effective September 1, 1985, all RCRA 
permittees who generate waste disposed of, treated, or stored on-site 
certify, on an annual basis, that the facility has waste minimization 
programs in place. In addition, section 3002(b) mandates that hazardous 
waste generators include a certification with their hazardous waste 
manifests that the generator has a waste minimization program in place 
and that the proposed method of off-site management minimizes threats 
to human health and the environment. In concert with these HSWA 
mandates, it is the Agency's policy to encourage source reduction 
(i.e., waste minimization) and waste treatment as preferable to 
disposal and dilution.
    EPA has recognized that successful implementation of the land 
disposal restrictions requires that, in general, dilution be prohibited 
as a partial or complete substitute for adequate treatment of 
restricted wastes. The legislative history indicates that such a 
prohibition ``is particularly important where regulations are based on 
concentrations of hazardous constituents'' (H.R. Rep. no. 198, Part I, 
98th Congress, 1st Session 38 (1983)).
    The Agency also opposes the dilution of hazardous wastes for 
several technical reasons. Most importantly, dilution is an 
environmentally inappropriate means to reduce toxicant concentrations 
because it does not reduce toxicant loadings to the environment. The 
same mass of toxicant is released to the environment when a diluted 
waste is disposed as would be if that same waste, prior to dilution, 
were to be disposed. While mass loading of the environment is itself a 
serious concern, the potential for environmental damage is magnified 
when toxicants (for example, pesticides and metals) bioaccumulate in 
the food chain. In addition, diluted wastes can create an unnecessary 
demand for scarce solid waste disposal capacity.
    For these reasons, dilution is generally prohibited as a means to 
achieve the exemption levels under today's proposal. Because today's 
rule proposes to amend the some of the current LDR levels by 
establishing minimize threat levels, allowing dilution as a means of 
achieving exemptions would be inconsistent with the ban on dilution 
included in the land disposal restrictions rule (40 CFR 268.3). In 
addition, dilution would be inconsistent with the Congressional purpose 
of encouraging waste minimization. Thus, today's proposed rule 
specifically prohibits dilution as a means of attaining the exemption 
levels except as provided under the LDR program under 40 CFR 268.3(b).

VIII. Implementation

    Today's proposed rulemaking would establish a generic set of 
constituent-specific exemption levels for listed hazardous wastes. 
Wastes with hazardous constituent concentrations below the generic 
exemption levels would be conditionally exempt from Subtitle C.5 
Today's proposed 

[[Page 66386]]
rulemaking would be self-implementing; that is, no prior governmental 
approval or review of documentation would be required before wastes are 
eligible to exit. Claimants of an exemption, however, would be required 
to meet certain prerequisites in addition to the generic constituent 
concentration levels before the wastes would be considered non-
hazardous. These testing and notification requirements are necessary to 
ensure that only those hazardous wastes which truly meet the exemption 
criteria exit the subtitle C system. In addition, certain testing and 
record-keeping conditions would be imposed to maintain the exemption to 
ensure that the waste continued to be eligible for the exemption. 
Failure to satisfy the conditions would void the exemption.

    \5\ Exempted wastes would continue to be solid wastes, and as 
such would require proper management under subtitle D and other 
applicable state laws.
---------------------------------------------------------------------------

A. Implementation Requirements

    To make an effective claim, persons would need to comply with the 
following requirements:

--The waste must be sampled and tested in accordance with a 
comprehensive sampling and analysis plan prepared prior to conducting 
sampling and analysis (EPA recommends, as guidance, using the basic 
elements of sampling and analysis plans described in Chapters One and 
Nine of SW-846);
--Representative samples collected in support of an exemption proposed 
in today's notice must consist of a sufficient number of samples to 
represent the spatial and temporal variability of the waste 
characteristics;
--The waste must be tested for all hazardous constituents except those 
that should not be present in the waste as defined by this rule, with 
documentation supporting determination not to test any constituent 
available on-site at the time of the notification;
--If the claimant must test for any hazardous constituents on table B 
of appendix X of 40 CFR part 261, the waste must also meet treatment 
standards for those constituents listed on UTS table of 40 CFR 268.48;
--A notification must be submitted to the Regional Administrator (or 
authorized State) (hereafter referred to as the implementation 
authority), along with
--A certification signed by the claimant's authorized representative 
attesting to the completeness and accuracy of the notification, and
--Verification that a notice of the exemption claim has been placed in 
a major local newspaper of general circulation.

    Any deficiencies in compliance with these requirements would 
prevent the exemption from being valid; that is, the waste would not 
exit the subtitle C system. Claimants would not be able to use their 
knowledge of the waste alone to make a determination. Furthermore, in 
order to defend a claim that a waste was exempt under today's proposed 
rule and thus exempt from hazardous waste regulation, claimants would 
bear the burden in an enforcement action of establishing that the waste 
in question met the exit levels and the other requirements for the 
exemption.
1. Testing Requirements
    In today's notice, the Agency is proposing concentration-based 
exemption criteria below which a listed hazardous waste would be 
conditionally exempt from subtitle C compliance. To best ensure 
accurate characterizations of constituent concentrations in these 
wastes, the Agency is also proposing sampling and analysis requirements 
for the exemption determination proposed today. Adherence to these 
requirements, however, does not ensure that the characterization is 
accurate and representative of a waste on a continual basis. It is the 
generator's responsibility to ensure that a waste always meets the 
exemption requirements proposed today for all appendix X of 40 CFR part 
261 constituents, regardless of which constituents the facility is 
required to test and how often testing is performed.
    To be eligible for an exemption, EPA is proposing that facilities 
must (1) demonstrate that each constituent of concern is not present 
above the specified exemption level in the waste, (2) demonstrate that 
the analysis could have detected the presence of the constituent at or 
below the specified exemption level, and, (3) where specified, comply 
with the LDR standards applicable to the waste. Today's proposed rule 
allows that any reliable analytical method may be used to demonstrate 
that no constituent of concern is present at concentrations above the 
exemption levels. It is the responsibility of the generator to ensure 
that the sampling and analysis is unbiased, precise, and representative 
of the waste.
    The Agency will consider that the exemption level was achieved in 
the waste matrix if an analysis in which the constituent is spiked at 
the exemption level indicates that the analyte is present at that level 
within analytical method performance limits (e.g., bias and precision). 
The Agency prefers this empirical demonstration of method performance 
through the successful analysis at the exemption level. The Agency 
requests comment on this and any other approaches to demonstrate method 
performance.
    In general, the Agency is proposing testing requirements that would 
consist of an initial test to characterize the waste as exempt, 
followed by subsequent testing to ensure ongoing compliance with 
constituents of concern. A generator of a listed waste on a one-time 
basis will only be required to comply with initial testing 
requirements. Wastes produced on an infrequent (batch) or continuous 
basis will have to comply with initial testing requirements and 
subsequent testing requirements as appropriate based on the volume of 
the waste. The Agency asks for comment on this general approach to 
testing requirements.
a. Data Evaluation
i. Compliance With the Exit Levels
    The Agency is requesting comment on three approaches of data 
evaluation.
    First, the Agency is proposing that, for exemptions under today's 
proposed rule, generators would be required to evaluate their waste 
based on the maximum detected concentrations of the exemption 
constituents. If any constituent concentration is greater than its 
specified exit level, then the waste would be ineligible for exemption 
under today's proposed rule. One advantage of this approach is that 
facilities can use process and waste knowledge to determine the 
appropriate number of representative samples without relying on a 
complex, potentially costly statistical approach to determine an 
appropriate number of samples. However, generators will need to be 
sufficiently knowledgeable about their waste and process to make an 
unbiased determination regarding the appropriate number of samples. 
Actual sample representativeness might be difficult to verify or 
otherwise assess (on a statistical basis). Finally, the level of 
uncertainty associated with the results cannot be defined. Because of 
this, under this approach, a single composite sample that validly 
exceeds the HWIR exit levels would indicate that the waste is hazardous 
and must be handled in Subtitle C.
    Second, the Agency requests comment on also allowing a second data 
evaluation method whereby the analytical results are evaluated in terms 
of an upper confidence limit around an average concentration. An 
example of one method for determining an upper confidence limit is 
presented in the statistical approach found in Chapter Nine of SW-846 
(Third Edition, as amended by Updates I, II, IIA, and IIB), 

[[Page 66387]]
where, for the purpose of evaluating solid wastes, the probability 
level (confidence interval) of 80 percent is used. Sample measurements 
for which the upper limit of the 80 percent confidence interval about 
the sample mean is below the regulatory level for the chemical 
contaminant are not considered to be present at levels of regulatory 
concern. One main advantage of this approach is that the number of 
samples is statistically determined and thus it eliminates any bias 
that might otherwise be introduced when using knowledge to determine 
the appropriate number of samples. In addition, the level of 
uncertainty associated with the results can be determined. However, the 
main disadvantage of this approach is that it could be more costly for 
some facilities than the proposed approach. For example, it might 
require multiple rounds of sampling to determine the mean and variance. 
Highly variable wastes may require the collection of many more 
additional samples than might otherwise be determined to be necessary 
using the first approach. However, this statistical approach allows 
occasional samples to be above exemption level, as long as the upper 
confidence limit of the data overall is below the exit level.
    The Agency also requests comment on a third data evaluation method 
that would allow facilities to use long-term average data to 
demonstrate compliance without consideration of the upper confidence 
limit. A rolling average of samples would be taken over the course of a 
year on a schedule determined by the initial sampling and analysis 
plan. As long as the average of the samples was below the HWIR exit 
level, the waste stream would be considered non-hazardous. This 
approach would have the advantage of being simpler than the second 
option, while allowing occasional exceedences of the exit levels by 
single samples, as long as the average concentration is below exit 
levels.
    EPA has modelled risk with the assumption that the constituents of 
concern are uniformly distributed within the waste at the exit 
concentrations. In discussion with the Hazardous Waste Identification 
Dialogue Group, some representatives noted that actual levels might 
need to average significantly below the exit levels if the exit 
criteria are to be consistently met. The second and third data 
evaluation methods discussed above help address this issue.
    However, EPA and the States have noted that the only practical 
approach for enforcement purposes is to independently collect samples 
for analysis (which may represent a composite of materials spatially or 
over a short time span) and to set up the regulation so that an 
exceedence by any single composite sample during an inspection could 
constitute a violation. It would then be the responsibility of the 
generator to refute this, using historic sampling data and possibly 
additional samples to show that the sample exceedence does not 
constitute an overall violation of the HWIR levels.
    EPA believes it is important to retain the practical approach 
whereby a single composite sample of a waste at some arbitrary point in 
time or space during a short visit is considered sufficient for 
enforcement purposes. However, because the exit numbers were modeled 
based on long-term average concentrations, the Agency requests comment 
on allowing occasional exceedences as long as the average concentration 
meets the exit level.
    In addition to the concern about enforceability, however, EPA has 
identified two additional concerns about using average concentration to 
determine compliance. First, not all waste streams would be disposed of 
in the same place. Thus the wastes may on average be in compliance when 
they are generated, but the wastes arriving at the disposal site 
(possibly from multiple sources) may not be, on average, below the exit 
levels. Second, EPA has not modeled the constituents for acute risk. 
While the average concentration of constituents may be below the exit 
levels, the occasional ``high'' concentration may be of concern due to 
acute health or ecological effects.
    One possible way to address some of these concerns is, in addition 
to requiring that the average meet the exit levels (as in the second 
and third data evaluation methods), EPA could require that all samples 
be below some ``peak'' concentration.
    Under this approach, if the average concentrations are below the 
exit levels, and all individual samples are below the higher peak 
level, then the generator would be in compliance and need take no 
further action to support the exemption. EPA or a State would then be 
able to confirm waste status without total reliance on the generator's 
data and without the expense of periodic sampling by EPA or the State. 
EPA requests comment on this issue, including any information on 
setting peak levels.
    For any of the three data evaluation approaches, representative 
samples must be collected in support of exemption under today's 
proposed rule, consisting of a sufficient number of samples to 
represent the spatial and temporal variability of the waste 
characteristics, regardless of how the sample number is determined.
    For the identification and handling of ``outliers'', the Agency is 
recommending that testing for outliers should be done if an observation 
seems particularly high or low compared to the rest of the data set. If 
an outlier is identified, the result should not be treated as such 
until a specific reason for the abnormal measurement can be determined 
(e.g. contaminated sampling equipment, laboratory contamination, data 
transcription error). If a specific reason is documented, the result 
should be excluded from further data evaluation. If a plausible reason 
cannot be found, the observations should be treated as a true, albeit 
extreme, value and not excluded from the data evaluation, as waste 
composition can vary. The Agency solicits comments on implementable 
techniques for the identification of analytical outliers.
    The results of the tests of all of the constituents on the 
exemption list would be required to show the constituent concentration 
to be at or below the exit level in order for the claimant to be 
eligible for an exemption. In the case where a constituent's exit level 
is based on the quantitation criteria (EQC, as described in section 
IV.E.), in addition to showing a non-detect at the exit level, the 
waste would be required to meet applicable requirements set forth at 40 
CFR part 268. Certain facilities may have difficulty quantifying a 
constituent at the exit level due to matrix interference effects, but 
the Agency expects exempted wastes to have relatively clean matrices 
such that exit levels should be able to be achieved. The Agency 
believes that the exit level must be met in order for a waste to exit 
Subtitle C; therefore, waste streams that cannot meet exit levels would 
not exit under today's rule. The Agency asks for comment on this 
approach.
ii. Wastewater and Nonwastewater Categories
    Throughout today's proposal and background documentation, all of 
the exit levels have been described as being applicable to two 
categories of wastes using the terms wastewater and non-wastewater 
6. EPA used these terms as an initial means of distinguishing two 
waste categories that are inherent to how the exit levels were 
developed, by taking into account how these wastes 

[[Page 66388]]
will be managed (i.e., stored, treated, and disposed), and also how the 
wastes would be expected to behave in the environment. In the 
development of the exit levels, several waste management units were 
evaluated in the underlying risk analysis. The units chosen for 
evaluation were those that are considered most likely to manage the 
types of wastes that would be expected to exit Subtitle C regulation 
under today's exemption. Although these units will likely receive to 
some degree both forms of waste, in general there are technical, 
physical, and sometimes legal constraints on what types of waste are 
managed in each. The Agency considered ash monofills, waste piles, and 
land application units as typically managing waste materials that can 
be considered ``solid'' or ``non-wastewater,'' while tanks and surface 
impoundments typically manage ``liquid'' or ``wastewater.'' Based on 
these assumptions, results from the analysis of risk from these 
specific waste management units were then used to generate the 
corresponding exit levels for non-wastewater and wastewater.

    \6\ The terms ``wastewater'' and ``non-wastewater'' are used 
generically in today's preamble and rule, and do not represent the 
land disposal restriction definitions in 40 CFR 268.2(d) and (f), 
although one option EPA is requesting comment on in this section is 
the use of those definitions.
---------------------------------------------------------------------------

    In considering how to develop final definitions and terms for these 
two waste categories, the Agency's goal is to establish definitions 
that are clear, concise, and easily distinguishable from other similar 
terms such that a generator can readily determine which set of exit 
levels to apply to the waste being evaluated for the exemption. EPA 
requests comment on three options for defining these two waste 
categories to determine which set of exit levels to apply to a listed 
waste eligible for today's proposed exemption. EPA emphasizes that 
these definitions will only apply in the context of today's exit rule.
    The Agency also requests comment on whether it is reasonable in all 
three options to allow a generator the alternative options of 
separating in the laboratory the solid (or nonwastewater) portion of 
the waste from the liquid (or wastewater) portion of the waste, 
analyzing the resultant portions, comparing the results to the 
corresponding exit levels, and treating the waste as exempt if all exit 
levels are met in both portions.
    Option 1: Using Percent Solids--EPA prefers the option of defining 
the two categories of exit levels as ``solid'' and ``liquid'' exit 
levels, where the distinction between solids and liquids is based upon 
the percent solids content of the waste, as determined using Section 
7.1 of the Toxicity Characteristic Leach Procedure (TCLP) in SW-846. 
Specifically, the option would define wastes containing 15 percent 
solids by weight or greater as solids,7, while wastes with less 
than 15 percent solids by weight be defined as liquids. EPA believes 
that the 15 percent cutoff is a reasonable distinction between the two 
categories of exit levels, for the following reasons. Because there are 
general prohibitions on liquids or wastes containing free liquids in 
non-hazardous waste landfills accepting municipal wastes, the Agency 
does not envision wastes containing less than 15 percent solids being 
managed in these units. Similarly, it is unlikely that waste containing 
less than 15 percent solids will be stored in waste piles due to 
obvious physical limitations. For land application units, EPA believes 
that 15 percent solids content by weight is a reasonable lower limit 
for the types of wastes typically managed in these units; indeed, this 
was the value used in the land application unit scenario in the 
groundwater modeling portion of the risk assessment underlying today's 
exit levels.

    \7\ EPA will avoid use of the term ``solid waste'' when 
describing the category of exit levels that are defined as solids 
under this option in today's proposal. This is to avoid confusion 
with the existing term ``solid waste'' in the RCRA program, which 
has specific statutory and regulatory definitions, which have no 
relationship to whether a waste is a physically a solid or a liquid.
---------------------------------------------------------------------------

    Because of these limitations, EPA believes that wastes containing 
less than 15 percent solids will more frequently be managed in the 
types of units associated with wastewater treatment, such as tanks and 
surface impoundments. In fact, EPA believes that many wastes falling 
into the liquid category under this definition, that can realistically 
exit under today's proposed exit rule, will likely be wastewaters that 
have undergone treatment and that contain much less than 15 percent 
solids. EPA presumes that in many cases the separation of water from 
solids will be occurring as part of routine wastewater treatment, and 
generators will be either be evaluating the solid residues (which would 
clearly meet our solid definition), or the treated water, much of which 
is currently discharged under the Clean Water Act and therefore likely 
has limits on the amount of solids present.
    EPA also requests comment on alternative ways of determining 
percent solids content, including generator knowledge of the waste or 
results of previous analyses. The Agency believes that in many cases, 
particularly for fairly dry or fairly wet wastes, the generator can 
immediately ascertain from a visual inspection that the percent solids 
content is well above or well below the 15 percent solids value.
    Option 2: Using LDR Definitions--EPA also requests comment on the 
use of the same terms and definitions currently used under the land 
disposal restrictions. Wastewater is defined as waste containing less 
than 1 percent total suspended solids (TSS) and less than 1 percent 
total organic carbon, or TOC (40 CFR 268.2(f)). Non-wastewater is 
defined as any waste that is not a wastewater (40 CFR 268.2(d)). The 
principle advantage of this approach is it allows the use of consistent 
definitions for wastewater and nonwastewater in both today's exit 
system for listed wastes, and the LDR program. The advantage of this 
consistency is particularly apparent for those cases where LDR 
treatment standards are conditions of exit under today's rule. One 
disadvantage of this approach is that it defines wastes containing 
greater than 1 percent TSS as non-wastewater, even though these wastes 
will likely be managed in wastewater treatment systems using tanks and 
surface impoundments, which is inconsistent with the way in which the 
results from the risk analysis were used in developing exit levels. The 
Agency requests comment on this approach as an alternative to Option 1.
    Option 3: Using the Paint Filter Liquids Test--The third option is 
to use the terms ``liquid'' and ``solid'' as in Option 1, but to use 
EPA Method 9095 from SW-846, the Paint Filter Liquids Test, to 
determine whether the waste being evaluated for exit is a liquid or a 
solid. Under this option, any waste determined to contain free liquids 
using Method 9095 would be considered a liquid, and the exit numbers 
currently in the wastewater category would apply to that waste. 
Conversely, a waste would be defined as a solid, and the nonwastewater 
exit levels would apply, if the waste does not contain free liquids 
using Method 9095. Under this option, EPA realizes that many wastes 
appearing like solid materials would actually be defined as liquids.
    Method 9095 is presently used in defining the term ``liquid waste'' 
in the solid waste disposal facility criteria, for determining 
compliance with the prohibition on disposing of bulk or containerized 
liquid in municipal solid waste landfills (see 40 CFR 258.28). Method 
9095 is also used in determining compliance with the prohibition on 
bulk or containerized liquids in hazardous waste landfills 
(264.314(c)).
iii. Totals and TCLP Analyses
    Today's rule proposes that the claimant would be required to test 
the waste for which today's exemption is 

[[Page 66389]]
being claimed to prove that constituent concentrations in the waste do 
not exceed the exit level(s) for each constituent that should be 
present in the waste.
    The claimant would determine which category of exit levels would 
apply (e.g., wastewater or nonwastewater) to his waste. In a previous 
section of today's rule, the Agency requests comment on several options 
to define these two categories. For a wastewater waste to be eligible 
for exit, every constituent in the waste must comply with the 
wastewater total constituent exit concentration. For a nonwastewater 
waste to be eligible for exit, every constituent in the waste must 
comply with the nonwastewater total constituent exit level as well as 
the nonwastewater leach exit level.
    A test for total concentration would be required for each 
constituent in the waste regardless of whether the waste is a 
wastewater or a nonwastewater to determine that the total constituent 
exit concentration has not been exceeded. For non-wastewaters, a 
claimant must also prove that the measurable leachate concentrations do 
not exceed the nonwastewater leach exit levels. The Agency proposes to 
allow claimants to either use a calculational screen or to use the 
Toxicity Characteristic Leaching Procedure (TCLP, Test Method 1311 in 
``Test Methods for Evaluating Solid Waste, Physical/Chemical Methods,'' 
EPA Publication SW-846) to make a determination that constituent 
concentrations do not exceed nonwastewater leach exit levels. 
Discussion concerning the methodology of a calculational screen is 
described below.
    Section 1.2 of the TCLP allows for a compositional (total) analysis 
in lieu of the TCLP when the constituent of concern is absent from the 
waste, or if present, is at such a low concentration that the 
appropriate regulatory level could not be exceeded.
    For wastes that are 100% solid as defined by the TCLP, the maximum 
theoretical leachate concentration can be calculated by dividing the 
total concentration of the constituent by 20. The dilution factor of 20 
reflects the liquid to solid ratio employed in the extraction 
procedure. This value then can be compared to the appropriate 
regulatory concentration. If this value is below the regulatory 
concentration, the TCLP need not be performed. If the value is above 
the regulatory concentration, the waste may then be subjected to the 
TCLP to determine its regulatory status.
    The same principal applies to wastes that are less than 100% solid. 
In this case, however, both the liquid and solid portion of the waste 
are analyzed for total constituency and the results are combined to 
determine the maximum leachable concentration of the waste. The 
following may be used to calculate the maximum theoretical 
concentration in the leachate.
[GRAPHIC][TIFF OMITTED]TP21DE95.000

where:

A = Concentration of the analyte in liquid portion of the sample (mg/L)
B = Volume of the liquid portion of the sample (L)
C = Concentration of the analyte in the solid portion of the sample 
(mg/kg)
D = Weight of the solid portion of the sample (kg)
E = Maximum theoretical concentration in leachate (mg/L)
If:

Eleach

Then: A TCLP need not be performed for this constituent because, even 
if 100% of the constituent leaches, the TCLP results would be less than 
the regulatory leach standard. This calculation is adequate proof that 
this waste is at or below its leach exit level.

    The above calculational screen may be used by a claimant in order 
not to perform the TCLP. The screen may be used to determine that a 
total analysis of the waste demonstrates that individual contaminants 
are at such low concentrations that the nonwastewater leach exit level 
could not possibly be exceeded, thus eliminating the need to run the 
TCLP.
    Example: To illustrate the calculational screen, the following 
example is provided: An analyst wishes to determine if a leach 
processing sludge could fail the nonwastewater leach exit level for 
lead. The sludge is reported to have a low concentration of lead, and 
the analyst decides to perform a compositional analysis (totals test). 
A representative sample of waste is subjected to a preliminary percent 
solids determination as described in the TCLP. The percent solids is 
found to be 90%. Thus, for each 100 grams of this waste filtered, 10 
grams of liquid and 90 grams of solid are obtained. It is assumed for 
the purpose of this calculation that the density of the filterable 
liquid is equal to one. The liquid and solid portion of the sample are 
then analyzed for total lead. The following data are generated:

Percent solids = 90%
Concentration of lead in the liquid phase = 0.023 mg/l
Volume of filtered liquid = 0.010 L
Concentration of lead in the solid phase = 85 mg/kg (wet weight)
Weight of the solid phase = 0.090 kg.
The calculated concentration is as follows:
[GRAPHIC][TIFF OMITTED]TP21DE95.001

    In this case, the maximum leachable concentration is below the 10 
mg/L regulatory concentration for lead, and the TCLP need not be 
performed.
iv. Oily Wastes
    In this proposed rulemaking, the Agency has modelled the transport 
of solutes in groundwater as well as movement along other environmental 
pathways. This groundwater modeling involves predicting rates of 
constituent leaching from wastes in land-based waste disposal units. In 
using this fate and transport modeling to develop regulatory exit 
levels, the Agency is proposing to rely on the use of leach tests to 
ensure that groundwater is not contaminated. Among the test methods 
that have been developed and employed to identify wastes which might 
pose an unacceptable hazard are: Methods 1310 (Extraction Procedure), 
1311 (Toxicity Characteristic Leaching Procedure, TCLP), 1320 (Multiple 
Extraction Procedure, MEP), and 1330 (Oily Waste Extraction Procedure, 
OWEP).
    However, these leach test procedures all have deficiencies in 
predicting the mobility of toxic chemicals from oily 

[[Page 66390]]
wastes. Method 1311 underestimates the mobility of constituents from 
many oily wastes due to filter clogging problems, can be imprecise for 
oily wastes, and has several operational problems. Conversely, Method 
1330 is believed to overestimate mobility of constituents from oily 
wastes since it emulates a worst case scenario by using solvents to 
extract contaminants from the oil. None of the available laboratory 
procedures is fully satisfactory. Rather, they bracket the range of 
possible leaching for oily wastes.
    In addition, EPA does not have a good definition for what 
constitutes an oily waste. EPA originally defined oily wastes as those 
materials that clogged the filter during Method 1311 (TCLP) extraction. 
EPA requests comment on how to better define what an oily waste is.
    EPA also requests comment on which of the two tests methods (1311 
or 1330) should be used and why should one test be chosen over the 
other for predicting the concentrations of contaminants in leachate 
from wastes being managed in landfills. EPA also requests comment on 
whether there are any alternative test methods or models that could be 
used for predicting the mobility of oily materials. Such procedures 
need to be both scientifically credible and environmentally protective. 
Methods need to identify material that might be released from the waste 
and enter the soil. Release is defined as movement of either the liquid 
phase of the waste or leached contaminants through the bottom of the 
waste unit to the subsurface soil immediately underlying the disposal 
point. Once contaminants pass this point their ultimate fate in terms 
of impact on down-gradient water supplies can be estimated by the 
ground-water fate and transport model (EPACMOW model).
    EPA also requests comment on any additional problems with oily 
waste leachability not covered here, and whether the volatilization or 
other attributes of constituents should be considered in the 
development of a test.
    Oily wastes also pose modeling challenges in groundwater because 
they do not disperse in the same pattern as aqueous liquids. This 
affects the movement of the constituents in the material. In the event 
of a release of waste at or near the soil surface, the waste will 
migrate downward until it reaches the water table. Light non-aqueous 
phase liquids (LNAPLs) will then tend to migrate laterally, forming a 
pancake on top of the water table. Dense non-aqueous phase liquids 
(DNAPLs) on the other hand will sink to the base of an aquifer and not 
show much lateral spreading until an impermeable layer is reached. EPA 
is requesting comment on what sort of wastes or what constituents 
exhibit these behaviors and how to define that set of wastes. 
Constituents that have been associated with DNAPLs include 
dichlorobenzenes, PCBs, napthalenes, chloroform, carbon tetrachloride 
pentachlorophenol, cresols, and several PAHs. However, trace amounts of 
these constituents are unlikely to pose a DNAPL problem. A DNAPL 
problem is likely to occur when there is sufficient concentration to 
flow as undissolved liquid that would then form the sort of complex 
reservoirs that subsequently slowly dissolve into groundwater. The 
Agency requests comment on concentrations of these or similar chemicals 
that are likely to pose DNAPL problems and whether the proposed exit 
levels in totals or, for nonwastewaters in leach levels, are sufficient 
to limit wastes exiting for which a DNAPL or LNAPL problem would need 
to be explicitly evaluated.
    The Agency is continuing to work on developing tests and models for 
determining the leaching potential of oily materials and may propose 
them in future rulemaking. In the meantime, EPA is today proposing to 
apply the levels as proposed in this rule to oily wastes, but seeks 
comment on whether instead there is a definable class of wastes for 
which these levels cannot reasonably be concluded to be protective.
b. Initial Test
    The Agency is proposing in today's rule that there would be an 
initial test before a facility would be eligible for an exemption. The 
initial test would be the primary tool to characterize the waste as 
exempt. Results from this initial test would be sent to the 
implementing agency. The public could request the implementing agency 
to make the results available.
    EPA is proposing to require initial testing of all of the 386 
constituents on appendix X of 40 CFR part 261 except those that the 
claimant determines should not be present in the waste. EPA would 
require the claimant to document the basis of each determination that a 
constituent should not be present. The claimant must submit the 
documentation to the implementing agency and retain a copy on site for 
three years. No claimant may determine that any of the following 
categories of constituents should not be present:

--Constituents set out in appendix VII to part 261 as the basis for 
listing the wastestream for which exemption is sought;
--Constituents listed in the table to 40 CFR 268.40 as regulated 
hazardous constituents for LDR treatment of the waste stream ;
--Constituents detected in any previous analysis of the same 
wastestream conducted by or on behalf of the claimant;
-- Constituents introduced into the process which generates the 
wastestream; and
--Constituents which the claimant knows or has reason to believe are 
byproducts or side reactions to the process that generates the 
wastestream.

The Agency requests comment on whether these are the appropriate 
criteria to be used to determine what should not be present in the 
waste. The Agency also requests comment on requiring claimants who are 
not waste generators to consult the generator prior to determining that 
a constituent is not introduced into the process or that a constituent 
is not a byproduct or side product of the process. EPA believes that it 
is unlikely that a non-generator claimant would have sufficient 
knowledge of the production process to make adequate determinations on 
these issues. EPA requests comment on the type of documentation that it 
should require. The generator could co-sign the document that sets out 
the reasons for determining that the claimant need not test for a 
constituent, or the generator could prepare a separate supporting 
document that would be attached to the document for submission to the 
implementing agency and retention in the claimant's files.
    The Agency is soliciting comment on whether the absence of 
constituents in the following documents could constitute sufficient 
justification for not analyzing all of the constituents listed in 40 
CFR part 261 appendix X.

--40 CFR part 261 appendix VII highlighted to show which constituents 
are listed for each waste code applicable to that waste;
--40 CFR 268.40 highlighted to show which constituents are regulated 
under the land disposal restrictions for each waste code applicable to 
that waste;
--EPCRA Toxic Release Inventory reports highlighted to show which 
constituents are reported as being ``used'' in the manufacturing 
process from which that waste is generated (based on the EPCRA 
definition of ``use'');
--NPDES discharge permits highlighted to show which constituents are 
required to be monitored in wastewaters with which that waste is 
commingled or will be commingled; 

[[Page 66391]]

--State or Local emissions monitoring permits or documents (e.g., stack 
emissions, fugitive emissions, groundwater monitoring, wastewater 
discharges, etc.,) highlighted to indicate which constituents are 
required to be monitored as potential emissions from units in which 
that waste is managed or will be managed;
--Responses to government and/or trade group data collection efforts 
(e.g., biennial reports, TSD surveys) that require submission of waste-
specific constituent information;
--Published literature (e.g., journals, presentations, chemical and 
engineering reference documents, health and safety handbooks, material 
safety data sheets, etc.,) highlighted to indicate constituents that 
are formed or potentially formed from side reactions, degradation, or 
reactivity of the products, reactants, or solvents used in the 
manufacturing process generating that waste;
--Plant-specific process flow diagrams or process descriptions 
highlighted to indicate constituents that are formed or potentially 
formed from side reactions, degradation, or reactivity of the products, 
reactants, or solvents used in the manufacturing process generating 
that waste;
--Product specifications or constituent-specific labeling requirements 
under federal regulations, state regulations, or non-governmental 
standards (i.e, per product-grade) that identify constituents that are 
expected to be present in the products from which the waste was 
generated, highlighted to indicate those constituents identified as 
part of these specifications or standards (excluding chemical additives 
or preservatives that are placed in the products subsequent to the 
generation of the waste for which exit is claimed);
--Waste profile data sheets, such as those submitted to commercial 
waste handlers, highlighted to show the constituents that were found or 
expected to be present in that waste; and/or
--A certified, third party engineering analysis of the process 
generating that waste that provides qualitative verification of the 
theories behind the anticipated absence of certain chemical classes or 
groups of Appendix X of 40 CFR 261 constituents such as pesticides, 
pharmaceutical, halogenated solvents, carbamate, organo-sulfur 
compounds, known gases, cyanides, etc.;
--Any other available quantitative or qualitative constituent 
information specific to that waste

    Relevant information includes not only those document sections that 
indicate which constituents are present, but also cover pages that 
indicate the source of the document segments and signature pages to 
verify authenticity of government-approved documents (where 
appropriate). For the verification purposes, page numbers should also 
be clearly identified for each document. EPA is also soliciting 
information on additional readily available documentation that could be 
added to this list that would not impose an unreasonable records burden 
on both the generator and enforcement officials (for example, the 
Agency believes that requiring highlighted copies of copious amounts of 
monitoring data would be redundant and would significantly impede 
enforcement review). EPA believes that requiring copies of only 
relevant portions of these documents, highlighted to indicate the 
chemicals present, should minimize the burden associated with this 
documentation requirement significantly.
    Regardless of which constituents a facility tests, the facility is 
responsible for ensuring that each constituent in the waste meets its 
applicable exit level.
    The Agency believes that the tailored initial test described above 
will ensure accurate waste characterizations of the waste streams while 
focusing testing requirements to those constituents that are of 
concern. A facility could determine whether a constituent would be 
present. A facility would not be authorized to determine that the 
constituents in the waste meet the exemption levels based on knowledge 
of the waste or material. This approach both reduces unnecessary 
testing costs and allows for more frequent monitoring of those 
constituents that are of concern.
    The Agency is soliciting comment on whether this proposed approach 
to an initial test is appropriate.
    The Agency asks for comment on taking the opposite approach: 
requiring each claimant to test only for those constituents that the 
claimant determines ``could be present'' for that waste. This would be 
a systematic way for facilities to focus the list of hazardous 
constituents to those that are mostly to be present in the waste. EPA 
requests comment on requiring at a minimum testing of the following 
categories of constituents:
--Constituents set out in appendix VII to part 261 as the basis for 
listing the wastestream for which exemption is sought;
--Constituents listed in the table to 40 CFR 268.40 as regulated 
hazardous constituents for LDR treatment of the waste stream ;
--Constituents detected in any previous analysis of the same 
wastestream conducted by or on behalf of the claimant;
--Constituents introduced into the process which generates the 
wastestream; and
--Constituents which the claimant knows or has reason to believe are 
byproducts or side reactions to the process that generates the 
wastestream.

    The Agency asks for comment on the completeness of the proposed 
mandatory testing criteria. In addition, the Agency requests comment on 
whether testing should be required for those constituents that do not 
meet any of the criteria of ``could be present.'' The Agency also 
requests comment on whether documentation should be required to 
demonstrate that those constituents that were not tested did not meet 
any of the ``could be present'' criteria.
    EPA requests comment on another approach to determining which 
constituents need to be analyzed by a claimant. The approach would be 
that the claimant needs to provide data on all additional constituents 
listed in appendix X of 40 CFR part 261 of today's rulemaking for which 
a method used by the generator to detect other constituents which the 
claimant is required to test can easily determine concentrations. Thus, 
for example, if a waste was listed for a constituent for which GC/MS is 
an appropriate method used by the claimant, the claimant would also be 
required to ask the laboratory to provide information on all other 
constituents listed in appendix X of 40 CFR part 261 of today's 
proposed rulemaking for which the GC/MS is also an appropriate method.
    EPA did not use this in its primary proposal because the Agency 
realized that implementation of this concept become more complex than 
it appears. For example, even when using GC/MS, there may be sample 
preparation techniques, dilutions, and similar issues that determine 
which constituents can be measured in the appropriate concentration 
ranges using the method.
    However, there is something intuitively reasonable and attractive 
in asking claimant to gather and provide information that is easily 
obtainable and would provide additional confidence and certainty. EPA 
solicits comments on this idea and ways to implement it.
    The Agency requests comment on whether there is some other way to 
focus the scope of testing requirements or if the only way to ensure 
accurate waste characterizations would be to require testing for all 
386 constituents.

[[Page 66392]]

    The FACA suggested EPA should define, for major waste streams, a 
set of constituents that it believes would fairly characterize those 
waste streams. The Agency believes such an approach may be desirable. 
However, the Agency notes that this could require it to expend 
significant resources. The Agency requests comments on the feasibility 
or need for this approach in the long term.
    EPA recognizes that some generators may wish to assert claims for 
protection of confidential business information (CBI) for some to the 
information that supports an exit claim. Material that is classified as 
CBI may be reviewed by EPA, but may not be released to the public. 
States may have similar provisions under state law. EPA requests 
comments on two options for addressing CBI information.
    First, EPA requests comment on the option of prohibiting any person 
from asserting a claim of exit under this rule if that person wishes to 
claim CBI protection for any data or information used to support the 
exit claim, including all information submitted to the implementing 
agency in the notification package and all information required to be 
maintained by the claimant on site and furnished to the agency on 
request. A generator who wished to rely on CBI data to support an 
exemption claim for a listed hazardous waste would need to file a 
delisting petition with EPA or a state authorized for delisting.
    EPA believes such an approach may be necessary because the exits 
proposed today are self-implementing. The public would not have the 
assurance of knowing that EPA or a state agency had reviewed the 
claimant's data and determined that it showed that the claimant's waste 
posed low risks to human health and the environment. Members of the 
public may not feel that they are adequately protected by the fact that 
EPA and authorized states could obtain the CBI data and use it (with 
appropriate precautions against disclosure) in an enforcement action if 
warranted. They may feel that the number of claims will strain agency 
inspection and enforcement resources, making it important for them to 
be able to bring their own citizen enforcement actions under section 
7002 of RCRA.
    At the same time EPA is sensitive to potentially legitimate 
business needs to protect information supporting an exit claim. Some 
firms may not wish to release detailed information about the chemical 
composition of their process waste streams. EPA also recognizes that 
the federal delisting process is considerably slower and imposes more 
procedural burdens than the self-implementing exit scheme. EPA requests 
comment on the alternative of creating a limited prior approval process 
for exit claims involving CBI claims. EPA anticipates that rulemaking 
would not be required. However, states that wish to obtain 
authorization for today's exit program might not be required to adopt 
this feature because they could argue that failure to provide a review 
process for CBI claims would not make their programs less stringent 
than the federal program.
    EPA also notes that CBI protection is not absolute. EPA has 
authority under RCRA to release CBI information to the public as 
necessary to support rulemaking proceedings. (In fact, EPA could try to 
support the first option above by arguing that it was exercising in 
this proceeding its authority to waive protection for all of the 
individual exit claims that ``implement'' the rule.) Also, a citizen 
that has sufficient evidence of a violation to file a complaint in 
court may be able to persuade the court to order a limited release of 
the data for use in the enforcement proceedings.
2. Notification Requirements
    The Agency is proposing that the required notification to the 
implementing authority would include the following information:

--The name, address, and RCRA ID number of the person claiming the 
exemption;
--The applicable EPA Hazardous Waste Codes;
--A brief description of the process that generated the waste;
--An estimate of the average and maximum monthly and annual quantities 
of each waste claimed to be exempt;
--Documentation for any claim that a constituent is not present;
--The results of all analyses and estimates of constituent 
concentrations and all quantitation limits achieved;
--Documentation that any constituents on Table B to appendix X of 40 
CFR part 261 have met the applicable treatment standards in 
Sec. 268.48, unless the claimant is claiming the exemption under 
Sec. 261.36(e);
--Evidence that the public notification requirements have been 
satisfied; and
--A certification signed by the person claiming the exemption or his 
authorized representative.

    The Agency is taking comment on whether the following additional 
information should also be sent to the implementing authority:

--The name and address of the laboratory which performed the analysis;
--A copy of the sampling and analysis plan used for making the 
exemption determination;
--A description of any chain-of-custody procedures;
--Whether the identity of the disposal facility should be included in 
the notification package;
--Dates of sampling and analysis; and
--A description of the (temporal and) spatial locations of the 
demonstration samples.

Also, the Agency is taking comment on whether, if the disposal facility 
is different than the claimant's facility, the claimant should also 
include as part of the notification package documentation that the 
claimant informed the disposal facility of the exempt status of the 
waste.
    A complete notification package would include all required 
information in the notification and all required certifications signed 
by the appropriate individual, as identified in the regulations. 
Failure to submit a notification package if the exemption is being 
claimed or submission of an incomplete notification package would be a 
violation of RCRA requirements and thus subject to penalties and 
injunctive relief under section 3008(a) of RCRA and possible criminal 
liability under section 3008(d) of RCRA. As a necessary prerequisite to 
claiming an exemption, the burden would be on the claimant to establish 
that a complete notification package was submitted to the implementing 
authority to assert in an enforcement action that the waste is exempt.
    It should be noted that, regardless of whether the sampling and 
analysis plan must be included with the notification to the 
implementing agency, a current sampling and analysis plan must be 
developed and used to establish the waste's eligibility for exemption, 
and must be available upon request to the implementing authority at the 
time the notification package is submitted and at least for three 
years. The sampling and analysis plan must demonstrate that the samples 
to be taken and analyzed will be representative of any spatial and 
temporal variations in the subject waste.
    Furthermore, it should be noted that submission of sampling and 
analysis plans with the notification to the implementing authority does 
not change the self-implementing nature of the exemption. Submission of 
such plans would not be for review or approval of exemption claims 
prior to the exemption becoming effective. The implementing agency 
would be under no obligation to undertake such review or approval prior 
to the exemption 

[[Page 66393]]
becoming effective, and failure to undertake such prior review would 
not preclude a subsequent enforcement action should the exemption claim 
later be determined to be inaccurate or otherwise invalid.
    As proposed, the certification required to accompany the 
notification must attest that the waste in question meets all relevant 
constituent concentration exit levels and that the information in the 
notification package is true, accurate, and complete. The Agency is 
taking comment on whether this certification is sufficient assurance 
that the claimant has made best efforts to accurately characterize the 
waste or if additional certification language or additional 
certifications (e.g., from an analytical laboratory) are necessary.
    The notification package would be required to be submitted by 
certified mail with return receipt requested, or other commercial 
carrier that provided written confirmation of delivery. No claim would 
be effective until the claimant received the return notification 
indicating that the package had been delivered.
    Submission of the notification package to the implementing 
authority, however, is not equivalent to approval or verification of 
the exemption claim. Submission of a notification package would not 
preclude or in any way limit the implementing authority's ability to 
take a subsequent enforcement action should it determine that the 
initial requirements of exemption were never met or that the conditions 
for maintaining the exemption are not satisfied.
    The Agency is taking comment on whether, instead of the exemption 
becoming effective upon confirmation of delivery of the notification 
package, there should be some brief waiting period prior to the 
exemption becoming effective.
    Such a period (e.g., 30 or 60 days) could be used by the 
implementing authority to review notification packages for completeness 
or for indicia of concerns that would lead to prioritized enforcement, 
although the exemption would still become automatic after the period 
regardless of whether any action was taken by the implementing 
authority. As an alternative, the period could be designed to provide 
the implementing authority an opportunity to determine that a claimant 
should not be able to avail itself of the exemption without some 
further review and to notify the claimant of its views.
    Under either approach, governmental review would be discretionary 
and the lack of such review would not be an indication of governmental 
approval of the exemption claim. To ensure that there would be no 
confusion on this point, the certification could include a statement of 
recognition that expiration of the delay period without comment by the 
overseeing agency is not the equivalent of agency approval that the 
claim is accurate. The Agency has not chosen to propose a delayed 
implementation approach because it believes a short time frame, 
particularly combined with an automatic effective date, would not 
provide an opportunity for thorough prior review and would, at best, 
provide only marginal benefits as a screening device for potentially 
problematic claims. The Agency, however, requests comment on whether 
such a delay would be beneficial to monitoring claims and if there are 
procedural or other concerns relating to such a delay.

B. Implementation Conditions

    After the exit claim has become effective, the claimant would have 
to continue to meet certain conditions to maintain the exemption. 
Failure to satisfy any of the conditions would void the exemption and 
subject the waste to applicable subtitle C requirements.
    Under this proposal, wastes must continue to meet the generic 
exemption levels established for exit to remain non-hazardous. Separate 
and distinct from any requirement or condition that might be 
established under this rulemaking, all generators--including claimants 
of today's proposed exemption--would have a continuing obligation to 
identify whether they are generating a hazardous waste and to notify 
the appropriate governmental official if they are generating a 
hazardous waste. Section 3010; 40 CFR 261.11. If wastes claimed as 
exempt under today's proposed rule test above exit levels at any time, 
that waste and subsequently generated waste would have to be managed as 
hazardous waste--including compliance with all notification 
requirements--until testing demonstrated that the waste was below exit 
levels.8

    \8\ Compliance with HWIR exemption levels will be measured from 
the last available test data or from the latest representative 
samples taken from the waste in question. Testing which shows 
constituent concentration levels above exemption levels will not 
affect wastes previously generated under a valid claim of exemption 
based upon representative samples. Similarly, testing, which shows 
that a waste which tested above exit levels once again tested below 
all relevant exit levels will exempt all waste generated on or after 
the date the samples were taken. Waste which exceeded the exit 
levels would not be able to requalify for the exemption.
---------------------------------------------------------------------------

1. Records Maintained on Site
    In addition to the information described in the Notification 
Section above, the Agency is also proposing that the following 
information concerning the initial testing and retesting be maintained 
in the files on site at the facility making the exemption claim for at 
least three years:

--All information required to be submitted to the implementing 
authority as part of the notification of the claim;
--The dates and times waste samples were obtained, and the dates the 
samples were analyzed;
--The names and qualifications of the person(s) who obtained the 
samples;
--A description of the (temporal and) spatial locations of the samples;
--The name and address of the laboratory facility at which analyses of 
the samples were performed;
--A description of the analytical methods used, including any clean-up 
and extraction methods;
--All quantitation limits achieved and all other quality control 
results for the analyses (including method blanks, duplicate analyses, 
matrix spikes, etc.), laboratory quality assurance data, and a 
description of any deviations from published analytical methods or from 
the plan which occurred;
--All laboratory documentation that support the analytical results, 
unless a contract between the claimant and the laboratory provides for 
the documentation to be maintained by the laboratory for the period 
specified in Sec. 261.36(b)(2) and also provides for the availability 
of the documentation to the claimant upon request;
--If the generator claims a waste is exempt from part 268 requirements 
pursuant to Sec. 261.36(e), documentation to substantiate such a claim.

    The Agency requests comment on the proposed information maintenance 
requirements and comment on additional information that may be 
necessary.
    In addition, claimants will be required to retain certain 
information concerning retesting of wastes as described below and set 
out in the text of proposed 40 CFR 261.36(d)(6)(ii).
2. Testing Conditions
    Claimants would continue to periodically test their wastes as a 
condition of the exemption.9 Failure to test and maintain 
documentation of the 

[[Page 66394]]
testing in accordance with the requirements of proposed 40 CFR 
261.36(d) would void the exemption. The Agency believes that required 
subsequent testing is necessary to maintain accurate waste 
characterizations. Subsequent testing would be an ongoing exemption 
condition and would be the minimum testing required to maintain an 
exemption. A tailored constituent list setting out minimum requirements 
for testing purposes should not be confused with the facility's ongoing 
requirement to maintain constituent concentrations below exit levels 
for all constituents on appendix X of 40 CFR part 261. Results from 
subsequent testing would be required to be maintained on-site.

    \9\  Wastes generated on a one-time basis would not be subject 
to this requirement.
---------------------------------------------------------------------------

    The scope of subsequent testing would focus primarily on those 
constituents from appendix X of 40 CFR part 261 that are of concern 
based on the initial test. The list of constituents for which a 
claimant would be required to test would, at a minimum, include each 
constituent that was detected in the initial test within an order of 
magnitude below the exit level for that constituent, and any 
constituent listed in Table B of appendix X of 40 CFR part 261 that is 
also identified as a basis for listing the waste or appendix VII to 
part 261 or listed as a regulated hazardous constituent for the waste 
in the table to 40 CFR 268.40. The claimant would also be required to 
test for any other constituent which the claimant had reason to believe 
was newly present in the waste since the most recent previous test.
    The Agency proposes that the frequency with which a facility would 
be required to perform subsequent testing would be determined based on 
the volume of waste which the facility is declaring exempt. Those 
facilities with large-volume waste streams would perform subsequent 
testing more often than those facilities with low- or medium- volume 
waste streams. The claimant would be responsible for determining the 
volume of annual exempt waste. The Agency asks for ideas and comments 
on whether guidance should be made available for claimants on how to 
measure annual volumes. Justification of annual volumes would be sent 
to the Director in the notification package. The Agency believes that 
accurate waste characterizations are important for waste volumes of all 
sizes; however, inaccurately characterized large-volume wastes have 
greater potential to harm the environment than do smaller-volume 
wastes. In today's rule, the Agency is proposing the following 
requirements for the first three years of subsequent testing:

--Wastes generated at the time of exemption is initially claimed in 
volumes greater than 10,000 tons/year would be tested four times a year 
for the first three years of the exemption.
--Wastes generated at the time of exemption is initially claimed in 
volumes greater than 1000 tons/year but less than 10,000 tons/year 
would be tested twice a year for the first three years of the 
exemption.
--Wastes generated at the time of exemption is initially claimed in 
volumes less than 1000 tons/year would be tested once a year for the 
first three years of the exemption.

    EPA requests comment on whether it should allow the Agency proposes 
that if a waste maintains exempt status for three years, the frequency 
of subsequent testing would then be reduced to once a year, regardless 
of the volume produced. The Agency believes that three years of 
subsequent testing should provide a facility with adequate data to 
assess the potential for variability in the waste. The Agency requests 
comment on the frequency of subsequent testing.
    The Agency requests comment on an approach that the FACA suggested. 
The approach consisted of a comprehensive test, similar to an initial 
test, that is required every 3 or 5 years of an exemption because of 
the strong reliance on the initial test's results in determining the 
scope of subsequent testing.
    The Agency also requests comment on whether follow-up testing 
should be eliminated entirely after the first three year period. In 
addition, the Agency asks if a certification of compliance with all 
relevant exit levels could suffice in lieu of testing at the end of 
three years.
3. Testing Frequency and Process Change
    Under today's proposal, the claimant has a continuing obligation to 
verify that the waste continues to meet the exemption criteria, 
including meeting the exemption constituent concentration levels. 
Process changes that may either increase the number of hazardous 
constituents in the exempted waste or increase the concentration of 
hazardous constituents already present, should put a claimant on notice 
that there may be changes in the waste that may affect its continued 
eligibility for exemption. The Agency, however, is not proposing to 
require new sampling and analysis whenever there is a process change 
that may affect the exempt status of the waste.
    The Agency is taking comment on whether it is necessary to require 
as a condition of maintaining the exemption that wastes be re-tested 
after a process change and, if so, what the scope of such re-testing 
should be. The Agency would like to know if the testing frequency 
proposed or more frequent testing would provide a clearer indicator of 
waste changes of concern than triggering re-testing through a narrative 
description of a process change. Another alternative is to require the 
claimant to notify the implementing authority that a process change has 
occurred and to certify that the exemption criteria continue to be met 
if the claimant determines that the waste still maintains its exempt 
status. The Agency is taking comment on how process change should be 
defined in the event one of the alternatives is chosen. It should be 
noted that if waste for which an exemption has been claimed at any time 
tests above exemption levels, that waste and all subsequently generated 
waste is hazardous. The claimant could not assert a new exit claim 
until a new batch of waste tests below the exit levels. The exemption 
proposed today would not relieve generators of their responsibility 
under Sec. 262.11, nor would any test data previously obtained prevent 
a claimant from failing to satisfy the exemption criteria should an 
inspector conduct waste sampling that establishes hazardous 
constituents at concentrations above exit levels.

C. Public Participation

    As a self-implementing exemption effective upon receipt of the 
notification by the implementing authority, there is no decision prior 
to exit being made by the implementing authority regarding the waste. 
The opportunity for public participation in an exemption claim is the 
opportunity that exists at all times for the public to bring to the 
implementing authority's attention any circumstance that might aid that 
authority in its monitoring and enforcement efforts. The public, 
furthermore, would have the ability to bring a citizen suit for a 
claimant's failure to comply with any requirement of the exemption.
    The Agency is proposing to require that the public be notified by 
the claimant that an exemption claim is being asserted. This 
notification would be accomplished by publication of a notice in a 
major newspaper, local to the claimant and of general circulation, that 
contains the information required by the regulations. Evidence that the 
notice has been submitted for publication must be part of the 
notification package submitted to the implementing facility. 

[[Page 66395]]

    The Agency is requesting comment on whether such a notice should be 
placed in a newspaper local to the claimant's facility or to the 
disposal facility or both, should those facilities be located in 
different areas not served by the same newspaper.
    Requiring notification of facilities receiving exiting wastes has 
also been raised to the Agency in discussions. The Agency solicits 
public comment on the need for and possible approaches to requiring 
that waste generators that are exiting their listed waste, notify 
receiving facilities that wastes are HWIR exited wastes. Additional 
discussion of this issue appears in the docket under ``Receiving 
Facility Notification Process.''
    As discussed above, the Agency is also taking comment on whether 
providing a ``delay'' in the effective date when the exemption attaches 
(e.g., 30 or 60 days) would provide a significant and meaningful 
opportunity for public comment prior to the waste having exited the 
subtitle C system. Possible benefits of a waiting period before 
effectiveness of the exit could include greater opportunity for State 
review or citizen comment before waste is actually disposed outside of 
Subtitle C. Under such an approach, the waiting period would begin with 
receipt by the State of a complete certification package, and would run 
for the designated time (30 or 60 calendar days).
    The Agency is taking comment on whether access to claim 
documentation through the appropriate implementing agency will be 
sufficient to provide public access to documentation. One alternative 
would be to require the claimant to provide access to the information. 
If that option is selected, the Agency requests comment on how, and for 
how long, the claimant should be required to provide access to the 
documentation, and on what kind of protection for CBI would be 
appropriate.

IX. Request for Comment on Options for Conditional Exemptions

    The Agency has at different times considered contingent management 
approaches to disposal of hazardous wastes. Under such approaches, 
wastes that would be considered hazardous if managed in an uncontrolled 
manner, could be considered non-hazardous if managed in a sufficiently 
controlled manner. The following section discusses and requests public 
comment on several approaches to setting higher exit levels tied to 
meeting certain management requirements. These approaches would allow 
wastes with higher concentrations of hazardous constituents to be 
managed safely outside of Subtitle C.
    Many Subtitle C requirements were written generically to address 
all hazardous wastes and, consequently, provide protection for those 
wastes that pose the greatest risks. Others are either explicitly or 
implicitly technology-based rather than risk-based. Some of these 
requirements are statutory and cannot easily be adjusted to take risk 
into account. Nevertheless, EPA generally believes that it would be 
desirable to tailor waste management requirements to more closely 
coincide with risks. The exit levels proposed today take an initial 
significant step in this process by allowing very low-risk hazardous 
wastes to be exempt from Subtitle C requirements, leaving them subject 
only to less prescriptive federal and state controls for nonhazardous 
wastes. They also take an initial step towards setting different exit 
levels for different situations by recognizing that wastewater and non-
wastewaters are typically handled in different ways and pose different 
risks, hence today's notice proposes different exit levels for 
wastewaters and non-wastewaters.
    Within the time constraints imposed by the court-ordered deadline 
for this proposal, EPA has begun exploring whether it would be possible 
to create additional exemptions to allow more flexible management of 
additional wastes now classified as hazardous without compromising 
protection of human health and the environment. These options are 
premised on the theory that a waste's risk is due not only to its 
chemical composition, but also the manner in which it is managed, which 
can greatly affect the amount of chemical constituents that ultimately 
reach a human or environmental receptor. The multipathway analysis 
prepared to support the exit levels shows that the concentration at 
which a hazardous constituent threatens human health or the environment 
varies significantly with the type of management that a waste 
receives--some forms of management appear to present greater risks than 
others. The following discussion presents the legal framework for 
management-based exemptions, and outlines in some detail the options 
which EPA finds to be most promising for rapid promulgation.

A. Legal Basis for Conditional Exemptions

    EPA originally interpreted RCRA's definition of hazardous waste to 
focus on the inherent chemical composition of the waste and to assume 
that mismanagement would occur so that people or organisms would come 
into contact with the waste's constituents. See 45 FR 33113 (May 19, 
1980). However, EPA even in the past tried to consider ``reasonable'' 
mismanagement scenarios, scenarios that where reasonably likely or 
plausible even if not proven to necessarily have occurred or be typical 
for a specific waste. However, after more than a decade of experience 
with waste management, EPA believes that it may no longer be accurate 
or necessary to assume that worst-case mismanagement will occur. In 
recent hazardous waste listing decisions, for example, EPA has 
identified some likely ``mismanagement'' scenarios that are reasonable 
for almost all wastewaters or non-wastewaters, and looked hard at 
available data to then determine if any of these are for some reason 
very unlikely for the specific wastes being considered, or if other 
scenarios are likely given available information about current waste 
management practices. As a further extension of that logic, EPA now 
believes it may be appropriate to find that, where mismanagement is not 
likely or has been adequately addressed by other programs, EPA need not 
classify a waste as hazardous and that there may be ways to recognize 
situations where the limitations on likely ``mismanagement'' are 
specific to a State, a type of waste, or a facility-specific condition 
on how a waste is managed.
    EPA believes that it can interpret the definition of ``hazardous 
waste'' in RCRA section 1004(5) to authorize this approach to 
classifying wastes as hazardous. Section 1004(5)(B) defines as 
``hazardous'' any waste which may present a substantial present or 
potential hazard ``when mismanaged''. EPA reads this provision to allow 
it to determine the circumstances under which a waste may present a 
hazard and to regulate the waste only when those conditions occur. 
Support for this reading can be found by contrasting section 1004(5)(B) 
with section 1004(5)(A), which defines certain inherently dangerous 
wastes as ``hazardous'' no matter how they are managed. The legislative 
history of Subtitle C of RCRA also appears to support this 
interpretation, stating that ``the basic thrust of this hazardous waste 
title is to identify what wastes are hazardous in what quantities, 
qualities and concentrations, and the methods of disposal which may 
make such wastes hazardous.'' H.Rep. No. 94-1491, 94th Cong., 2d Sess.6 
(1976), reprinted in A Legislative History of the Solid Waste Disposal 
Act, as Amended, Congressional Research Service, Vol.1, 567 (1991) 
(emphasis added).
    EPA also believes that section 3001 provides it with flexibility to 
consider 

[[Page 66396]]
the need to regulate wastes as hazardous. Section 3001 requires that 
EPA, in determining whether to list or otherwise identify a waste as 
hazardous waste, decide whether a waste ``should'' be subject to the 
requirements of Subtitle C. Hence, section 3001 authorizes EPA to 
determine that Subtitle C regulation is not appropriate where a waste 
is not likely to be managed in such a way that it will threaten human 
health or the environment. Moreover, regulation of such waste under 
Subtitle C would not appear ``necessary to protect human health or the 
environment'' under RCRA sections 3002(a), 3003(a) and 3004(a). As 
noted elsewhere in this proposal, EPA interprets these provisions to 
give it broad flexibility in fashioning criteria to allow hazardous 
wastes to exit the Subtitle C regulatory system. EPA's existing 
regulatory standards for listing hazardous wastes also allow 
consideration of a waste's potential for mismanagement. See 
Sec. 261.11(a)(3) (incorporating the language of RCRA section 
1004(5)(B)) and Sec. 261.11(c)(3)(vii) (requiring EPA to consider 
plausible types of mismanagement). Where mismanagement of a waste is 
implausible, the listing regulations do not require EPA to classify a 
waste as hazardous.
    Two decisions by the U.S. Court of Appeals for the District of 
Columbia Circuit provide potential support for this approach to 
defining hazardous waste. In Edison Electric Institute v. EPA, 2 F.3d 
438, (D.C. Cir. 1993) the Court remanded EPA's RCRA Toxicity 
Characteristic (``TC'') as applied to certain mineral processing wastes 
because the TC was based on modeling of disposal in a municipal solid 
waste landfill, yet EPA provided no evidence that such wastes were ever 
placed in municipal landfills or similar units. This suggests that the 
Court might approve a decision to exempt a waste from Subtitle C 
regulation if EPA were to find that mismanagement was unlikely to 
occur. In the same decision the Court upheld a temporary exemption from 
Subtitle C for petroleum-contaminated media because such materials are 
also subject to Underground Storage Tanks regulations under RCRA 
Subtitle I. The court considered the fact that the Subtitle I standards 
could prevent threats to human health and the environment to be an 
important factor supporting the exemption. Id. at 466. In NRDC v. EPA, 
25 F.3d 1063 (D.C. Cir. 1994) the Court upheld EPA's finding that 
alternative management standards for used oil promulgated under section 
3014 of RCRA reduced the risks of mismanagement and eliminated the need 
to list used oil destined for recycling. (The Court, however, did not 
consider arguments that taking management standards into account 
violated the statute because petitioners failed to raise that issue 
during the comment period.)

B. Improvements in Management of Non-Hazardous Waste and in Risk 
Assessment Methodology

    EPA's early regulations defining hazardous waste reached broadly to 
ensure that wastes presenting hazards were quickly brought into the 
system. When EPA promulgated its first listings and characteristic 
rules in 1980, its knowledge of toxic constituents, constituent 
transport pathways, and waste management options was more limited than 
it is today.
    In addition, significant changes and improvements in waste 
management have occurred since the early 1980's. Many states have 
established or strengthened industrial nonhazardous waste programs 
since that time. For example, currently 26 states require liners and 28 
states require ground-water monitoring for at least some surface 
impoundments. Up to 45 states require ground-water monitoring and 38 
states require liners for at least some landfills. It is important to 
recognize however, that within a state, applicable requirements may 
vary according to a number of factors, including unit type, waste 
source, and location. See ``State Requirements for Industrial Non-
Hazardous Waste Management Facilities'' EPA 1994. At the same time, 
industries have gained experience in managing wastes and many have 
improved waste management practices under incentives such as public 
access pursuant to the Emergency Preparedness and Community Right to 
Know Act, and avoiding liabilities under Superfund, RCRA corrective 
action and state cleanup programs.
    EPA's ability to predict the risks that a waste may pose has also 
improved significantly. EPA has collected much more data on a variety 
of waste management units and other factors that impact the ability of 
waste constituents to reach a receptor. Models such as the EPACMTP and 
the models used in the multipathway analysis provide more sophisticated 
means of assessing the risks of a range of waste management options. As 
a result of all these changes, EPA is now in a position to begin to 
implement a more carefully tailored risk-based approach to regulating 
hazardous wastes.

C. Overview of Options for Conditional Exemptions

    The Agency has identified several different approaches to providing 
conditional exemptions that would allow more wastes to exit the 
Subtitle C system. These options fall into two broad categories: (1) 
Establishing national conditional exemptions based on unit type either 
with or without assuming additional management controls; and (2) 
granting conditional exemptions to qualified state programs that ensure 
additional management controls.
1. National Approach: EPA Would Establish National Exit Levels for 
Contingently Managed Waste
    The contingent management program could be adopted by any state 
that wants to implement it, without consideration of state programs for 
non-hazardous waste. The contingent exit levels would differ according 
to the degree of management/disposal restrictions imposed as a 
condition of exit. The possible options would include progressively 
more restrictive requirements, and allow progressively higher exit 
levels as disposal options are further restricted. The options under 
this approach are:
a. Distinguish Between Disposal in Land Application Units and Other 
Units
    The multipathway risk assessment methodology used for this 
rulemaking takes into account management scenarios (such as land 
treatment of a waste), or exposure pathways (such as wind transport 
from an uncovered pile or volatilization from an open tank), resulting 
in calculated exit levels based on the riskiest scenario. In some cases 
this exit level may be significantly lower than the next most risky 
exposure pathway. The riskiest exposure pathway may not be applicable 
to some management situations. On review of the risk analysis results, 
the Agency determined that disposal in a land application unit is 
frequently the highest risk disposal option in both the multipath and 
groundwater modeling.
    As described in detail in Section X. below, the Agency has 
developed for proposal an approach to contingent management relying on 
the multipathway exposure analysis, risk level of 10-6 and HQ of 1, and 
using the base case uncontrolled management scenarios, but with land 
application units removed from the analysis. Exit concentrations would 
still be protective across a wide variety of conditions nationally, for 
all non-land application unit disposal. The Agency is proposing 

[[Page 66397]]
one national exit level for each constituent based on the next riskiest 
pathway, on condition that wastes are not disposed in land application 
units.
     This option was considered by the Agency to be the simplest 
approach to contingent management. It would be somewhat easier to 
enforce than other options described below, since there would still be 
only one conditional exit level for each constituent. Implementation 
mechanisms to assure that the wastes go only to allowable unit types 
are described below.
b. Unit-Specific Exit Levels for Each Disposal
    Another approach to contingent management considered by the Agency 
would be to establish a set of exit levels for each waste management 
unit evaluated based on risks at unregulated units of that type. Units 
that would be evaluated, at HQ 1 and 1 E-6 risk, would be land 
application units, waste piles, landfills, surface impoundments and 
tanks. Base case assumptions would be used to describe the units. The 
Agency has not included specific exit levels for this approach here, 
but solicits comment on its potential benefits, and potentially greater 
complexity of implementation and compliance assurance.
    Under option 2 the Agency would set separate exit levels for each 
type of waste management unit. Generators would be allowed to choose 
the type of non-subtitle C waste management unit in which to manage 
their waste, and would be required to meet the unit-specific exit 
levels for all constituents in order to manage the waste in that unit. 
Testing and implementation would be similar to the requirements for 
exit based on the most limiting pathway. However, the Agency believes 
this option would increase the complexity of tracking wastes that met 
the varying concentration exit levels tied to specific allowable units.
    The Agency believes allowing use of exit levels tailored to waste 
management can be a practical and appropriate way to allow greater 
volumes of waste to exit Subtitle C without increasing risks to above 
the toxicity benchmarks described in Section IV.D, providing that 
characteristics of various waste unit types can be clearly defined 
(such as the difference between surface impoundments, tanks, and 
perhaps covered tanks for the management of wastewaters), and providing 
the Agency can design a viable implementation scheme that does not rely 
primarily on statements of proposed future disposal. Tracking and 
monitoring of actual waste management could be one way to assure 
disposal in the appropriate facilities. Limiting disposal to on-site 
facilities could also better assure proper disposal, although this 
would limit the usefulness of contingent management approaches. The 
Agency requests comment on additional implementation requirements that 
might be needed to assure the waste is managed in the designated unit 
type only.
    EPA has not developed this as a general approach in this rulemaking 
because the risk modelling that was done, while more multifaceted and 
comprehensive than many past analyses, was not designed for this 
purpose. For efficiency in modelling, EPA did not always model each 
pathway for each specific unit. EPA sometimes only modelled an exposure 
pathway of concern (such as air emissions) from certain types of units 
that EPA thought might be the limiting scenario, and risk from organic 
constituents in a landfill were not modeled. Therefore the modelling 
work to date may not identify the most limiting pathway if each unit is 
judged individually. To fully develop exit levels for a full range of 
unit types, EPA believes it would have to do supplemental risk analysis 
to fill in the gaps in modeling for each of the waste management units, 
or at least evaluate whether the risk analysis done to date is 
sufficiently representative. Tables 21-39 in the November 1995 
Supplement to the multipath analysis present the modeled risk values 
for each constituent disposed in each of the five options modeled, and 
for each pathway. These tables can aid commenters in understanding what 
a unit-specific exit value for any particular constituent could be.
c. Consideration of Additional Management Unit Design or Management 
Practices
    A third option is that EPA would use a somewhat modified 
multipathway exposure model to evaluate whether adding additional 
specific design or operating controls for particular unit types, would 
allow less conservative exit levels. These conditional exit 
concentrations would be promulgated on a unit-type specific basis, and 
could be used only by units employing the specified additional controls 
that would reduce the risk level to 10-6. Such an approach could be 
self-implementing for a facility owner/operator, and would not 
necessarily be tied into a permitting authority.
    While such an approach could take into account the effects of a 
combination of added controls on each unit type (such as size of the 
unit, ground-water monitoring, liners, caps, etc.) the Agency believes 
that there are a number of significant implications associated with 
this approach. It could be interpreted by industries and states as an 
indirect way to define a broader set of management standards for 
industrial non-hazardous waste management units. Also, if the approach 
were self-implementing, it could be extremely difficult to ascertain 
that a particular unit meets a complex set of controls and therefore to 
assure compliance with the conditional exit levels. The more complex a 
judgement required to determine compliance with the conditions (such as 
whether a liner that is hard to inspect during operation is properly 
installed and protected from tears), the more appropriate it is likely 
to be that such determinations be made in the context of a permitting 
authority or prior approval rather than as a condition on a self-
implementing exemption.
    As a variation on this approach, The Agency could take into account 
certain regional, local, or site-specific factors in establishing exit 
levels. These could include the effect of local rainfall, regional 
hydrogeology, or size of facility on exit values. These issues are 
described in greater detail in section 3 below.
    Because of the complexity of implementation, the Agency would 
attempt to define very limited additional control(s) to limit exposures 
and reduce risks to 10-6 level. EPA particularly asks for comments on 
unit design attributes that are easily ascertainable in a spot 
inspection versus those that require more detailed engineering review, 
or review or monitoring of operations. For this option, as with options 
one and two, the Agency would have to conduct additional risk modelling 
work to adequately evaluate additional parameters on a unit specific 
basis.
    One issue common to all of the options discussed above is the legal 
status of wastes subject to such conditioned exemptions when there is a 
violation of the conditions. The Agency requests comments on how to 
make them enforceable in a practical way that is fair to those 
involved. If the waste concentration/unit requirements are conditions 
of an exemption, any violation of a condition means that the waste 
generator, or other individual managing the waste, has violated the 
full range of RCRA requirements and has been illegally managing a 
``hazardous waste'' as a ``nonhazardous'' waste. Because the 
conditional requirements are not clearly tied to other non-hazardous 
waste authorities, 

[[Page 66398]]
there would not be a remedy for the violations outside of the hazardous 
waste program. An alternative approach is discussed in the following 
options allowing conditional exit levels in states with qualified 
industrial non-hazardous waste programs. As long as the state has clear 
enforcement authority under its non-hazardous waste management program, 
these conditions could be crafted so that a violation of the condition 
was not illegal disposal of hazardous waste involving multiple RCRA 
counts. Rather it would be enforced as a violation of the relevant 
State authorities. The Agency requests comment on the advantages and 
disadvantages of these approaches, as well as whether there might be 
other approaches to ensure adequate legal remedies for violations of 
the conditional exit requirements, when the contingencies are not based 
on qualified state industrial non-hazardous waste programs.
2. State Program Approach
    As noted earlier in this section, many state industrial non-
hazardous waste programs have improved significantly since the early 
days of Subtitle C. State programs may offer the advantages both of 
requiring management controls which ensure protection of human health 
and the environment and ongoing oversight on a facility specific basis 
through permitting, inspection and enforcement activities. While every 
state program may not be operating at the same level, the Agency 
believes that a number of state programs may offer reasonable, 
protective systems to serve as the basis for less stringent exit 
levels. Qualified state programs would be allowed to manage listed 
waste in their non-hazardous waste management program under certain 
conditions. These qualified state programs would ensure that risks were 
reduced to protect human health and the environment.
    There are three key factors the Agency believes would need to be 
considered in establishing state-based contingent management programs. 
These are (1) establishing a risk-based cap on waste constituent 
concentrations that can be managed contingently; (2) the type of 
program review of a state program that EPA would perform to identify 
qualified state programs, and (3) the breadth of state program 
controls.
    For the risk cap, the Agency has considered using either a 1 E-4 
cancer risk and HQ 1, or 1 E-3 cancer risk and HQ 10 as options. The 
caps would be modeled based on management in unregulated disposal 
facilities, as in the base-case exit level modeling.
    Regarding program review, the Agency would either conduct a 
qualitative review of the State program, examining it to ensure it 
addresses key considerations, or would require states to conduct 
quantitative risk assessment of planned management practices to 
demonstrate their safety down to 1 E-6 cancer risk and HQ 1 or an 
alternative risk target.
    For the qualitative review, EPA would specify environmental and 
administrative performance goals and the state would have to submit a 
narrative description demonstrating how the particular combination of 
technical standards and administrative requirements in their program 
protects human health and the environment and meets those performance 
goals, for example:
     Ground-water protection: A state program must address 
adequately contamination of groundwater from a facility.
     Surface water protection: A state program must address 
adequately prevention of contamination of surface water which may occur 
through the run-off of pollutants from the disposal facility to surface 
waters.
     Address other environmental and performance goals such as 
controlling air exposures, siting, ensuring long-term integrity of the 
site, etc.
     Permitting and enforcement authorities and public 
participation: A state program has appropriate authorities and a system 
for prior approval of waste management facilities, and public 
participation either on a site-specific basis or for input to 
development of class permits.
     Adequate resources: A state program has adequate resources 
for administration of the program including permitting, inspections and 
enforcement.
    Under a quantitative risk review approach, a state would have to 
document their permitting and enforcement authorities and public 
participation requirements, as well as the adequacy of their program 
resources. The state would also have to demonstrate to EPA how the 
particular combination of technical management controls or design 
standards in its industrial non-hazardous waste program would ensure 
meeting 10-6 risk levels. In order to do this, EPA would have to refine 
or expand the multipathway exposure model. EPA would then either make 
its multipath model available to states or work with them to 
demonstrate that unit-specific state program controls would meet the 
10-6 risk level for a particular class of facilities receiving 
conditionally exited wastes. The Agency solicits public comment on 
whether states can propose alternative risk targets for use in state 
contingent management programs.
    Regarding program breadth, the Agency believes either broad, state-
wide programs, or more narrowly focused contingent management programs 
could be developed. Under a broad-based state program approach, the 
Agency would approve as qualified only those state subtitle D programs 
that adequately regulate all state non-hazardous waste management and 
wastes. Under this approach, states with programs deficient in certain 
aspects would be required to upgrade before participating in the 
contingent management program. However, the Agency recognizes that 
state subtitle D programs vary widely in the particular units and waste 
types that are covered, among other factors. Therefore, as an 
alternative approach, EPA might determine that a program qualifies for 
conditional exit only for particular units (i.e. for landfills only, or 
for landfills and surface impoundments, etc.). In other cases, a state 
program might focus narrowly on developing appropriate contingent 
management for particular waste streams generated by key industries in 
the state.
    In considering how to use these key factors in developing 
contingent management regulations, the Agency identified three options 
in addition to the three options described above under the national 
programs. These will be identified in this discussion as options four, 
five and six.
    Under option four, the Agency would use the 1 E-4 and HQ 1 risk cap 
on waste and would conduct a qualitative review of the state program 
using the criteria described above. This could be done either on a 
narrow program basis, or based on a program that qualifies broadly.
    Under option five, the Agency would also use the 1 E-4 and HQ 1 
risk cap for waste being contingently managed, but would require that 
states conduct risk modeling of proposed disposal to demonstrate that 
risks from the waste as disposed would be not greater than the 1E-6 and 
HQ1 risk targets of the base case. This approach could be taken either 
with the entire state program, or only certain waste management 
practices. In particular, site-specific factors, as described below, 
could be considered under this approach. These could include facility 
size, local rainfall, or local hydrogeology, among others. Location of 
the nearest drinking water well might also be considered by the state 
in evaluating risks, if allowed under state regulations and regulatory 
policies. In this case, the state would be 

[[Page 66399]]
required to demonstrate to EPA, using the multipathway analysis or 
another risk assessment model, how they would ensure on a site-specific 
basis that facilities disposing of conditionally exited wastes meet a 
10-6 risk level. Development of this approach might also require quite 
different risk models, since the multipathway model as it currently 
exists incorporates a number of simplifying assumptions to capture a 
broad range of possible conditions. The Agency would have to ensure 
that a model used for this analysis can incorporate complex site-
specific variables, or develop a set of simplified models that could be 
applied by states. However, this approach would provide maximum 
flexibility to states and generators to tailor exit levels to 
particular waste and site characteristics.
    Under option six, the Agency would allow wastes posing up to 1 E-3 
cancer risk and HQ 10 (in an unregulated management setting), and allow 
either a qualitative or quantitative review of the state program, but 
allow participation only by state programs that are broadly qualified, 
i.e., that are qualified in all aspects of the program, for currently 
managed industrial non-hazardous waste. The Agency would be more 
comfortable with this approach because it would be more assured of safe 
management of the waste regardless of where in the state it is 
disposed.
    The Agency also solicits public comment on whether more than one of 
the options discussed above should be developed at the same time. For 
example, the Agency might establish both the option 1 proposal 
described below, and establish a state-based contingent management 
program based on any of options four, five or six. By doing so, the 
Agency would establish option 1 as a minimum national standard, but 
this approach would allow that states to go further they choose to do 
so.
3. Establish Exit Levels That Consider Regional or Site-Specific 
Factors That Might Affect Constituent Fate and Transport'
    In addition to facility design factors, there are other location-
specific factors that may substantially affect the risks and the 
appropriate exit levels for waste management units. Examples of such 
factors include: Rainfall and hydrogeology at the site and the distance 
to off-site receptors. The average amount of precipitation falling on 
these waste management units may affect both the amount of leachate to 
groundwater and soil run off to off-site receptors. Thus, the Agency 
could determine geographic regions based upon climatic zones, could 
require precipitation data from the most appropriate certified rain 
gauge, or could require site specific precipitation information. 
However, in order to do this the Agency would need to verify that the 
other model inputs are appropriate for each of the regions or else 
develop new region-specific inputs. Therefore, the Agency solicits data 
and comment on technically appropriate ways to establish exit levels 
based on rainfall levels.
    Other site-specific factors that may significantly affect the 
groundwater pathway are the hydraulic conductivity of the soil 
surrounding the waste management unit and the distance to the nearest 
drinking water wells. If the hydraulic conductivity of surrounding soil 
is relatively low--such as in soils dominated by clays--then the flow 
of any potentially contaminated leachate to ground water could be 
effectively retarded for long periods of time (though flow to surface 
waters or other pathways might change, perhaps increasing). Landfills 
located in soils with low hydraulic conductivities (for example, 10-6 
cm/sec or lower) could provide an extra level of environmental 
protectiveness for ground water that could be considered in developing 
this approach. For example, the Agency might address this effect by 
developing exit levels corresponding to different classes of hydraulic 
conductivity. Alternatively, differences in hydraulic conductivity 
could be considered through a site-specific process. This approach 
would not be relying on engineered controls, but on natural attributes 
of the location. EPA solicits comments on whether such attributes can 
be readily determined or in what circumstances they can be readily 
determined and relied upon.
    The Agency did some limited sensitivity analysis with respect to 
ground water risk modelling to look at the concept of developing 
different exit levels depending on broad hydrogeological regions. The 
results of that analysis are in the docket. The Agency requests comment 
as to the value of investing in this approach and practical 
considerations the Agency should weigh in deciding whether to pursue 
this approach.
    Finally, where the nearest drinking water wells are at an unusually 
great distance from the waste management unit, corresponding exit level 
concentrations associated with groundwater exposures that took that 
distance into account could be significantly lower if the Agency's goal 
were solely the prevention of current exposure to groundwater 
contamination. However, many states have policies to not degrade 
groundwater and EPA believes it is quite difficult to predict future 
needs for uncontaminated groundwater. EPA believes that the groundwater 
modelling done for this rule reflects a balanced view by using the 
distribution of nearest wells. However, EPA expects it will receive 
comments suggesting that it should consider allowing facilities with no 
moderately nearby drinking water wells to take that into account. The 
Agency seeks comment on the implementation issues associated with 
taking these factors into account and the related policy judgement as 
to whether the goal of more site-specific assessment should be 
prevention of risk based on current ground water use, reasonably 
foreseeable use, or based on distances that would be more protective of 
the potential future use of ground water.
    The Agency also seeks comment on other location-specific factors or 
combinations of factors that may be particularly important in 
mitigating the risks associated with waste disposal. The Agency also 
requests comment on alternative approaches for taking these location-
specific factors into consideration in developing exit levels for waste 
management. One option for doing so would be to develop additional 
tables of exit levels (in addition to Option 2) for waste management 
units that reflect the effect of some of the most important location-
specific factors (e.g., exit levels for areas with low annual rainfall, 
or indexed to landfill size). As an alternative option, the Agency 
could develop ``reduced form'' equations that specifically relate the 
exit level concentration to critical location-specific factors (such as 
annual rainfall). The Agency requests comment on the merits of these 
approaches and on alternative options that might be used to better 
accommodate the effect of location-specific factors on exit levels.

D. Land Disposal Restrictions for Contingent Management Options

    Any conditional exemption would offer much more significant relief 
if it eliminated or reduced the need to comply with more stringent LDR 
treatment requirements. As explained above in Section VI of today's 
proposed rulemaking, however, under Chemical Manufacturers Association 
v. EPA (the ``Third Third'' decision) LDR treatment standards generally 
continue to apply even if a waste ceases to be classified as a 
hazardous waste. If an LDR treatment standard were lower (more 
stringent) than a contingent management exit level, the waste would 
still need to meet the LDR standard.

[[Page 66400]]

    EPA has proposed two approaches to integrating HWIR exit levels and 
LDR treatment requirements for the base option. First, EPA is proposing 
that LDR treatment requirements will never apply to wastes that meet 
all applicable exit levels at the point of generation. Second, for 
wastes which meet exit levels subsequent to the point of generation 
and, consequently, remain subject to the LDR regime, EPA is proposing 
to allow some exit levels to serve as alternative risk-based treatment 
standards meeting the ``minimize threat'' standard under RCRA section 
3004(m). EPA expects these proposals to reduce the burden of complying 
with LDR requirements.
    As explained more fully in the detailed presentation of option 1 
below, EPA is proposing both of these approaches for contingent 
management option 1 (relaxed exit values for wastes that are not placed 
in land application units). EPA's rationales are set out in that 
discussion.
    EPA anticipates that it might also be willing to propose to use 
exit levels developed under option 2 (separate exit levels for each 
major type of waste management unit) to serve as risk-based ``minimize 
threat'' standards. If EPA filled the gaps in its current multipathway 
risk assessment, it would feel fairly confident that the multipathway 
analysis plus the groundwater analysis identified constituent 
concentrations that minimize threats to human health and the 
environment for each class of waste management units. The modeling for 
both analyses would assume each type of unit was located in a 
``reasonable worst case'' physical setting and was subject to minimal 
management controls. EPA, however, would expect some members of the 
public to argue that unit-specific exit levels should not be considered 
``minimize threat'' levels because risks to human health and the 
environment would not be minimized if exempted waste ended up in the 
wrong type of management unit. EPA might try to address such concerns 
by imposing conditions such as tracking or reporting systems on persons 
claiming the exemptions.
    EPA would expect similar objections to the option of allowing 
wastes that meet option 2 levels to exit if their constituent 
concentrations met unit-specific exit levels at the point of 
generation. Members of the public might again be concerned about the 
possibility that wastes could be placed in a unit type requiring lower 
(more restrictive) exit levels. As suggested above, however, EPA could 
impose conditions to help ensure that exempted waste goes only to a 
unit where the exit levels in fact minimize threats.
    Providing LDR relief for the remaining options for conditional 
exemptions would raise additional legal and practical issues. All of 
the remaining national and state-based options rely on design or 
operating controls (such as liners) to help prevent dangerous 
concentrations of hazardous constituents from reaching human or 
environmental receptors. EPA, for example, would be reluctant to take 
into account control measures that would be difficult for inspectors to 
verify during site visits.
    It might be somewhat easier to take into account factors--such as 
annual rainfall, depth to groundwater, and subsurface soil and rock 
formations--that relate to a unit's physical setting. EPA has already 
proposed to interpret section 3004(m) to allow consideration of a 
unit's physical setting in making site-specific minimize threat 
findings. See the proposed LDR standards for contaminated soil, 58 Fed. 
Reg. 48123 and 48155 (Sept. 14, 1993). EPA requests comments on all of 
these issues related to the integration of conditional exemption 
options to the LDR standards.

E. Contingent Management of Mixed Waste

    The Department of Energy (DOE) has also expressed interest in EPA's 
contingent management approaches to managing waste that is mixed 
radiologic and RCRA hazardous waste (``mixed waste''). Mixed waste may 
be managed by DOE-regulated facilities or commercial facilities 
regulated by the Nuclear Regulatory Commission (NRC). EPA expects that 
the general approach in today's proposed regulation would be applicable 
to mixed wastes as well as listed-only hazardous wastes. DOE has 
suggested that because mixed wastes subject to RCRA are also subject to 
AEA disposal requirements which control releases of and exposure to 
radioactive hazards, these AEA requirements may address releases of 
chemically hazardous constituents as well, and it would be reasonable 
to allow more mixed wastes to exit Subtitle C because of the AEA 
requirements. DOE believes these AEA requirements would also provide 
adequate protection of human health and the environment from 
chemically-hazardous constituents. DOE has submitted several studies to 
EPA in support of their views, and the Agency has placed those 
documents in the public docket for review. The Agency will also 
undertake a review of these data to better understand the additional 
increment of protection provided by AEA low-level waste site 
performance standards. With that review ongoing, the Agency is 
proposing, and requesting public comment on, adaption of option four 
above to DOE's special circumstances. The Agency requests comment on 
allowing mixed waste meeting conditional exit levels for chemical 
toxicity estimated at 10-4 cancer risk and HQ 1 (modeled at an 
uncontrolled site), to exit Subtitle C if managed in AEA disposal 
facilities.
    DOE has also urged the Agency to consider establishing a 
categorical exclusion from RCRA requirements for mixed waste debris 
that is immobilized. One of several macro- or microencapsulation 
methods could be used to immobilize the debris, including use of 
portland or other cement products, or various polymer products. Under 
such an exclusion, all immobilized mixed debris could be managed 
outside of Subtitle C, but would still be required to be disposed in 
AEA disposal facilities. No testing of the debris would be required to 
identify toxic constituents or the levels at which they might be 
present. DOE has conducted a study of leaching rates for certain toxic 
constituents from stabilized debris and submitted it to the Agency for 
review in support of DOE's conclusion that immobilized debris can be 
managed safely outside of subtitle C if disposed in an AEA facility. 
Because the Agency has only recently received this study, it has been 
unable to adequately review and evaluate the data presented. The Agency 
solicits public comment on this approach, the DOE study, and solicits 
any other available data that are relevant to this topic.
    Finally, DOE has developed data on vitrified waste, and requested 
that the Agency consider the environmental protection conferred by this 
treatment process. Again, the Agency has not had adequate time to 
review and evaluate the DOE data, but has placed it in the public 
docket and solicits public comment on the data and DOE's preferred 
approach to mixed waste management.
    In soliciting comment on these exit procedures for mixed waste, the 
Agency recognizes that a number of states hosting DOE facilities have 
expressed concern over the proposal's effect on their states ability to 
adequately regulate mixed waste under states and federal law as 
intended by RCRA and the Federal Facilities Compliance Act. These 
states also believe that significant details of the DOE proposal are 
lacking and additional analysis would need to occur before the 
procedures can receive adequate comment. Therefore, the Agency intends, 
to the extent consistent 

[[Page 66401]]
with the schedule negotiated in the consent decree for this rulemaking, 
to publish a supplemental proposal on HWIR mixed waste exit criteria 
after initial comments have been received. The supplemental proposal 
would further describe the regulatory options being considered and will 
solicit additional comment on more specific options.

X. Implementation of Conditional Exemption Option 1

A. Introduction

    Using the concept of contingent management, EPA is proposing to 
create a second, alternative set of exit levels for nonwastewaters that 
are managed in landfills or monofills, but not land treatment units. 
Persons wishing to utilize this alternative exit scheme would not only 
have to meet the recalculated concentration limits for all constituents 
in their wastes, but also comply with conditions prohibiting land 
treatment. Compliance with notification and tracking requirements 
described in more detail below will also be necessary. The exit levels 
for this alternative are set out in appendix XI of 40 CFR part 261; the 
requirements and conditions are set out in proposed Sec. 261.37. 
Nonwastewaters that do not meet the exit levels in appendix X to 40 CFR 
part 261 will be eligible for exit only if they meet the more relaxed 
levels in appendix XI of 40 CFR part 261 and comply with all relevant 
conditions.
    EPA derived the levels for this alternative by deleting all of the 
modeling results for the land treatment scenario from its risk 
assessment data base, and selecting the lowest remaining exit value 
from the remaining modeling results for other types of waste management 
units. The same approach used to establish exit levels presented in 
Section V. of today's proposed rulemaking was used to establish exit 
levels under this option. That is, where complete risk data was not 
available, surrogates were used to extrapolated exit levels (see 
Section IV.H) and where analytical limitations existed, EQCs were used 
as exit levels (see Section IV.I). As a practical matter, this approach 
affects only the exit levels for nonwastewaters. As explained above in 
section IV, EPA created the original exit levels for nonwastewaters by 
grouping the modeling results for the unit types typically used to 
manage solid materials (ash monofills, piles, and land treatment units) 
and selecting the lowest value from all pathways modeled for these 
scenarios. EPA created the separate wastewater exit levels by grouping 
the results from units typically used to manage liquid wastes (tanks 
and surface impoundments). Consequently, the wastewater exit levels are 
not based on the modeling of land treatment units, and these levels are 
not affected by the decision to exclude results from the land treatment 
scenario.
    The Agency is proposing that the contingent management exemption be 
self-implementing. Therefore, the claimant would have the burden of 
demonstrating that all of the provisions for the contingent management 
exemption described herein have been met. In an enforcement action, a 
waste for which a contingent management exemption is claimed would be 
considered a Subtitle C hazardous waste unless the claimant was able to 
produce evidence that all of the conditions of the exemption have been 
met.

B. When Contingent Management Exemptions Become Effective

    The Agency is proposing two options for the point at which the 
contingent management exemption would become effective.
1. Option 1A--Placement of the Waste in a Qualifying Unit
    Under the first option, the conditional exemption for ``contingent 
management'' nonwastewaters would not become effective until the waste 
had been placed in a qualifying unit. Prior to actual disposal, the 
nonwastewater would be managed as a hazardous waste according to all 
applicable RCRA provisions, including 40 CFR parts 262 (for generators) 
and 263 (for transporters) and part 268 (regarding treatment prior to 
land disposal). These requirements include compliance with the waste 
manifest provisions of 40 CFR part 262, subpart B, and the pre-
transport provisions of 40 CFR part 262, subpart C, which contains, 
among other provisions, the provisions governing hazardous waste 
accumulation. Treatment and storage prior to disposal would remain 
subject to parts 264, 265, and 270.
    The Agency believes this approach makes it easier to ensure 
consistent implementation and safe management of the waste. It also 
decreases the potential implementation concerns that may arise if some 
states adopt this rule as part of their authorized programs and others 
do not. For example, this approach would reconcile transportation 
concerns that could arise if waste, conditionally-exempt in one state, 
were transported through a state that had not adopted the contingent 
management exemption as part of its authorized program.
    Under this option, the Agency is considering and requesting comment 
on the applicability of amending 40 CFR 264.1 and 265.1 to allow off-
site disposal facilities to store candidate contingent management 
exempt wastes for up to 10 days without becoming a subtitle C 
treatment, storage, and disposal facility, prior to ultimate disposal 
in a monofill or landfill. The Agency requests comment on whether 10 
days is a sufficient or appropriate length of time, and if not, what 
time period may be appropriate.
    Under the above approach, contingent management exempt 
nonwastewaters being disposed of on-site also would not become exempt 
until placed in a disposal unit meeting the requirements established 
under this rule. However, since the current waste accumulation 
provisions of 40 CFR 262.34, allow a generator to store hazardous waste 
on-site in tanks, containers or containment buildings for 90 days 
without becoming a Subtitle C storage facility, EPA believes that this 
approach should not place undue burdens on a generator. EPA requests 
comment on whether Sec. 262.34 will in fact enable generators of exempt 
nonwastewaters to store wastes on-site in unpermitted units for a 
reasonable period of time prior to land disposal. EPA acknowledges that 
nonwastewaters are typically not stored in tanks.
2. Option 1B--Effective Upon Meeting the Exit Levels
    The second option that EPA is considering would allow a 
nonwastewater to become exempt from all hazardous waste requirements 
except part 268 as soon as it meets appendix XI of 40 CFR part 261 exit 
levels and the claimant has met all the requirements and conditions of 
the exemption, including certifying that the waste will be managed in a 
monofill or land disposal unit. The goal of this approach is to ensure 
nonwastewaters will not be managed in a land treatment unit, which was 
found to pose the greatest risk for many routes of exposure. Under this 
approach, storage, treatment and transportation of the nonwastewater 
could take place outside of Subtitle C control upon meeting the 
requirements and conditions for the exemption. If EPA were to adopt 
such an approach, it would impose conditions to ensure that the 
exempted nonwastewater reached the types of units for which the 
exemption was designed. Various options are suggested below in Section 
D.1.
    Finally, EPA notes that the proposed approaches have different 
implications for LDR relief. These differences, which 

[[Page 66402]]
principally concern the availability of LDR relief for nonwastewaters 
which meet the appendix XI of 40 CFR part 261 exit levels at their 
point of generation, are discussed in more detail in section H. below.

C. Requirements for Obtaining an Exemption

    The following requirements would be applicable to both of the 
approaches discussed above. Requirements for meeting the contingent 
management exemption would include the sampling and testing 
requirements of Sec. 261.37 (b)(1), the public notice requirements of 
Sec. 261.37 (b)(3) and the notification to the implementing Agency 
requirements of Sec. 261.37 (b)(4), similar to those respective 
requirements for the base exemption in Secs. 261.36 (b) (1), (3) and 
(4). The Agency notes that these provisions would be directly 
enforceable Subtitle C requirements imposed prior to obtaining an 
exemption rather than conditions for maintaining the exemption.
1. Sampling and Testing Requirements for Contingent Management 
Exemptions
    The Agency is proposing that the sampling and testing requirements 
for the contingent management exemption be the same as those proposed 
for the base exemption in Section 261.36 (b)(1). The Agency requests 
comment on whether the sampling and testing requirements for the base 
exemption would be appropriate for the contingent management exemption.
2. Requirements for Public Participation in Contingent Management 
Exemptions
    To provide the public with access to information, the Agency is 
proposing to require compliance with the public notice requirements in 
proposed Sec. 261.37(b)(3), similar to those in Sec. 261.36(b)(3). The 
first time a claimant provides the Agency with notification of an 
exemption claim for contingent management wastes, he will be required 
to publish a notice of the claim in a major local newspaper general 
circulation. The notice must include the name and address of the 
facility, the description of the waste (as contained in the 
notification), a brief general description of the process producing the 
waste, an estimate of the quantities of waste claimed to be exempt, and 
information about the Agency where the claimant has sent the 
notification and supporting information. In addition, the public notice 
must include that the waste meets the contingent management exemption 
levels in appendix XI of 40 CFR part 261 and that the waste will be 
disposed of in a monofill or land disposal unit.
3. Notification Requirements for Contingent Management Exemptions
    To qualify for a contingent management exemption, a claimant would 
need to submit to the authorized State Agency Director a formal 
notification of its claim that waste meets the contingent management 
exemption levels in Appendix XI of 40 CFR part 261 and will be managed 
in accordance with the management conditions. In addition to the 
requirements under Sec. 261.36 (b)(4), the contingent management 
exemption notification to the implementing Agency must include an 
accompanying certification that the waste meets the contingent 
management exemption levels in appendix XI of 40 CFR part 261 and that 
the waste will be disposed of in a monofill or land disposal unit.
    The Agency requests comment on whether these requirements, similar 
to Sec. 261.36 (b)(1),(3) and (4), will provide adequate information to 
the implementing agency and the public on what exemption levels, i.e., 
appendix X to 40 CFR part 261 or appendix XI of 40 CFR part 261, are 
being claimed and on how the waste is being managed. These provisions 
would be requirements rather than conditions.

D. Implementation Conditions

    As set out in Sec. 261.37 (d) and explained in the base exemption 
implementation preamble (section VIII. B., Implementation Conditions) 
certain conditions have to be met to maintain the exemption after the 
claim has become effective. Under both option 1A and 1B, the following 
conditions would have to be met to maintain the contingent management 
option: Submitting changes in notification information to the Director 
within 10 days of the change, following the schedule for retesting, 
preparing and complying with a sampling and analysis plan for every 
retest, maintaining constituent concentrations in the nonwastewater at 
or below the exemption levels in appendix XI, meeting applicable 
treatment levels under Sec. 268.40, and maintaining records on-site for 
three years. These conditions are very similar to those proposed for 
the base exit in Section VIII of today's proposed rulemaking. In 
addition to those conditions established for the base exemption, the 
claimant would also have to ensure that the waste was managed in a 
qualifying unit.
    Claimants, under both options, always have the obligation to 
identify whether they are generating a hazardous waste and to notify 
the appropriate government official if they are generating a hazardous 
waste. (Section 3010; 40 CFR 261.11.) If any nonwastewater claimed as 
exempt under the contingent management proposal tested above the exit 
levels in appendix XI to 40 CFR part 261 at any time, that waste and 
any mixture or derived-from forms of that waste would have to be 
managed as hazardous waste, including compliance with all notification 
requirements, until testing demonstrated that the waste was below the 
exit levels.
1. Tracking Conditions
    EPA is proposing to modify the manifest regulations to reflect the 
fact that wastes exiting under this exemption need not be disposed of 
in treatment, storage or disposal facilities that are subject to the 
requirements of Sec. 264.71-264.72 or Section 265.71-264.72 requiring 
the facility that receives the waste to sign and return the manifest. 
EPA is not proposing to require the owners and operators of 
nonhazardous waste facilities that accept wastes exempted under this 
option to comply with these duties. As EPA concluded when it decided 
not to extend recordkeeping duties related to the LDR program to 
nonhazardous waste facilities accepting de-characterized hazardous 
wastes, it would probably be difficult to provide reasonable notice to 
all the members of this diverse universe, which has little or no other 
contact with the hazardous waste management regime, of these Subtitle C 
responsibilities.
    EPA is proposing instead that the claimant of the exemption be 
responsible for ensuring that the manifest is returned and that it--or 
some other document--provides information showing that the facility 
designated on the manifest did in fact receive the waste and did place 
it in a landfill or monofill (and not a land treatment unit). Billing 
documents may already supply some of the needed information. Where they 
do not, EPA believes that claimants should generally be able to 
contract with the receiving facilities to obtain the necessary 
information. In some states, nonhazardous waste rules may also require 
disposers to furnish generators with some of the necessary information. 
EPA proposes to revise the manifest document as necessary to ensure 
that nonhazardous waste facilities can be designated as receiving 
facilities for listed wastes meeting all of the other requirements for 
obtaining an exemption under this option.

[[Page 66403]]

    The alternative to this approach would be to require owners and 
operators of nonhazardous waste facilities to sign and return manifests 
as a condition of the exemption. Failure to satisfy this condition 
would void the exemption and return the waste to the hazardous waste 
management regime, even if it were in fact safely placed in an 
appropriate waste management unit. EPA requests comment on this 
alternative.
    Under option 1A, where all Subtitle C regulations apply until 
placement of the nonwastewater in a monofill or landfill, EPA is 
proposing conditions that make the claimant responsible for obtaining a 
copy of the manifest to ensure the waste has reached its destination. 
The claimant would also have the burden of acquiring evidence from the 
receiving facility that the waste was placed in either a monofill or 
land disposal unit.
    Under Option 1B, where the exemption becomes effective upon the 
waste meeting the appendix XI of 40 CFR part 261 exit levels, any 
tracking system established would be a condition that the claimant 
would have to meet to maintain the contingent management exemption. To 
ensure that listed wastes exempted under this option actually go to a 
landfill or monofill, EPA is proposing to require exemption claimants 
to comply with the requirements of part 262 (with the modification 
discussed above) relating to the uniform hazardous waste manifest.
    Since this option allows wastes to go to facilities that are not 
subject to the duty to return the manifest under Sec. 264.71-264.72 or 
Sec. 265.71-264.72, EPA is proposing to require the claimant to ensure 
that the manifest is returned and that it--or some other document--
provides information showing that the facility designated on the 
manifest did in fact receive the waste and did place it in a landfill 
or monofill (and not a land treatment unit). The duties would be 
identical to those proposed above for claimants under the first option. 
The rationale for imposing the duties on the claimant--and not the 
receiving facility--is also the same.
    An alternative which EPA requests comment on is the concept of 
imposing conditions that require a uniform, national tracking document 
similar to the current uniform manifest to accompany the waste until it 
reaches its final destination. This document could inform transporters 
and other waste handlers that the waste is an exempt hazardous waste 
that must be managed in a monofill or land disposal facility and loses 
its exemption if it is managed in a land treatment unit. EPA could 
further require that the disposal facility certify that the 
nonwastewater was disposed in a monofill or land disposal unit and 
return the tracking document and certification to the original 
exemption claimant. EPA could also ensure that the implementing agency 
(EPA or an authorized state) received notice of any problems in waste 
disposal by imposing requirements similar to the current Sec. 262.42 
exception reporting provisions.
    Another alternative would be to require, in lieu of a tracking 
document, a contractual agreement between the exemption claimant and 
the receiving facility specifying the type of waste the receiving 
facility will accept, the type of units it will use, and information on 
the volume and frequency of deliveries. EPA could require either the 
claimant or the receiving facility (or both) to maintain a copy of the 
agreement on-site and make it available to state or EPA inspectors. EPA 
also could require exemption claimants and transporters to create and 
keep similar contracts. EPA, however, requests comment on whether 
transporters would require claimants to provide information on the 
exempted waste's origin and the regulatory limits on its disposal 
options even without federal regulation.
    EPA requests comment on whether any of these alternatives can 
adequately ensure that mismanagement will not occur so that these 
wastes managed under this option 1B approach would not need to be 
classified as hazardous.
2. Qualifying Unit
    A ``qualifying unit'' for today's contingent management proposal is 
a landfill or monofill. For purposes of today's proposal, a landfill is 
defined in Sec. 260.10 as being ``a disposal facility or part of a 
facility where hazardous waste is placed in or on land and which is not 
a pile, a land treatment facility, a surface impoundment, an 
underground injection well, a salt dome formation, a salt bed 
formation, an underground mine, a cave or a corrective action 
management unit.'' The Agency is proposing a definition for monofill in 
Sec. 260.10 as a landfill where waste of only one kind or type is 
placed in or on land and which is not a pile, a land treatment 
facility, a surface impoundment, an underground injection well, a salt 
dome formation, a salt bed formation, an underground mine, a cave, or a 
corrective action management unit. Also, for today's proposal, a land 
treatment facility is defined in Sec. 260.10 as being ``a facility or 
part of a facility at which hazardous waste is applied onto or 
incorporated into the soil surface; such facilities are disposal 
facilities if the waste will remain after closure.'' The Agency 
requests comment on whether other units could be considered 
``qualifying units'' for contingent management exempt waste and whether 
additional modeling is needed to assess risks from management of 
nonwastewaters from other units.
    The Agency modeled risks from waste piles in both its multipathway 
and groundwater analyses. It modeled only groundwater risks form 
landfills. As explained elsewhere in this preamble, EPA believes that 
the nongroundwater risks posed by piles generally are higher than the 
nongroundwater risks posed by landfills. EPA, however, is not proposing 
to allow wastes placed in piles to be exempt under the exit levels for 
contingent management option 1. Piles, as defined in Part 260, are 
temporary units. To ensure that exempted wastes removed form piles went 
only to landfills or monofills, EPA would have to impose additional 
tracking conditions. These could be difficult to craft and enforce 
effectively. EPA currently thinks that excluding piles from eligibility 
will provide much better assurance that exempted wastes will not be 
mismanaged.
    EPA acknowledges that the exit levels for this option, which are 
based in many cases on the evaluation of waste piles, may, for some 
pathways, be more restrictive than levels for landfills. If EPA later 
completes a multipathway analysis of landfill units, it will be able to 
use the levels from that modeling in lieu of the modeling from piles to 
derive exit levels for this option.
    The Agency requests comment on the proposal to exclude wastes 
placed in piles from being eligible for exemption under this option. 
The Agency also requests comment on the alternatives of allowing wastes 
to be exempt either permanently or temporarily (e.g., for one year) 
after they are placed in piles.
3. Claimant's Duty To Ensure Compliance With All Requirements and 
Conditions
    Today's proposal requires that, in order to claim a contingent 
management exemption, the person submitting the claim must manage the 
waste for which the exemption is claimed in accordance with the 
requirements and conditions established by this rule. To satisfy this 
rule, the claimant must ensure that the waste is actually disposed of 
in a qualifying unit. The burden of satisfying all conditions for the 
exemption falls on the claimant as the person in the best position to 
determine eligibility of a waste for an exemption and to ensure 
informed waste management decisions. The claimant may enter into 
contractual 

[[Page 66404]]
arrangements with receiving facilities to allocate responsibility for 
satisfaction of the conditions among themselves although such 
arrangements will not relieve the claimant of liability if the 
receiving facility manages the waste improperly. It should be noted, 
however, that facilities receiving contingent management exemption 
wastes could also become liable for violations of permitting, Subtitle 
C treatment, storage and disposal standards should they dispose of the 
nonwastewaters that do not qualify.
    Under today's proposal, Sec. 261.37(g), the burden of proof to 
establish conformance with the exemption criteria is on the claimant in 
the event of an enforcement action. One alternative for simplifying the 
claimant's burden of proving compliance with all conditions would be to 
set out in the rule certain documentation that, while not necessarily 
required of the claimant, presumptively would be sufficient evidence of 
satisfaction of the management condition. Of course, EPA could rebut 
this presumption regarding actual disposal through evidence that the 
claimant's documentation is deficient or inaccurate. For example, 
claimants might be able to develop rebuttable evidence of proper off-
site disposal by keeping correspondence with the receiving facility, 
indicating that the waste went to a landfill or monofill, and by 
keeping a returned manifest which indicates that the waste reached that 
facility. The Agency is taking comment on whether establishing certain 
evidentiary standards would provide useful guidance to claimants on how 
to satisfy the management condition and provide helpful incentive for 
claimants to maintain proper documentation of their exemption claims.
    Comment is also requested on whether any additional conditions or 
requirements, substantive or procedural, should be imposed on claimants 
to ensure that the contingent management exemption waste is actually 
managed in a qualifying unit.

E. Retesting and Recordkeeping Conditions for Contingent Management 
Exemptions

    Claimants continuing to generate or otherwise manage waste for 
which they continue to claim a contingent management exemption would be 
required, under Sec. 261.37(d)(2), to retest the waste with the same 
frequency and under the same conditions as is being proposed for the 
base exemptions, Sec. 261.36(d)(2). If a claimant finds that the 
exempted waste no longer meets the constituent concentration levels on 
Appendix XI of 40 CFR part 261 for the contingent management exemption, 
or that the waste has not been placed in a landfill or monofill, the 
claimant must comply with all applicable requirements for generators of 
listed wastes (including disposal of waste at a Subtitle C facility) 
and the disposal facility would have to comply with all of the 
requirements for owner/operators of treatment, storage, and disposal 
facilities under 40 CFR parts 262-270. The generator and disposal 
facility's obligations would also include renotifying the Agency of 
hazardous waste management activity using EPA form 8700-12.
    Under Sec. 261.37(d)(6), claimants also would be required to 
maintain on-site, for at least three years after Agency receipt of the 
notification and certification, all documentation required under this 
rule including, but not limited to, the sampling and analysis plan and 
test data and the accompanying notification and certification. These 
requirements are similar to those proposed for the ``base'' exemption 
in Sec. 261.36.
    The Agency requests comment on alternative record retention periods 
for claimants such as 5 years, which corresponds to the applicable 
statute of limitations period at 28 U.S.C. 2462. An extended record 
retention period may assist claimants in substantiating their 
conformance with the contingent management exemption criteria. The 
documentation must be available for review by the Agency or an 
authorized State at the time of site inspection. The three-year 
claimant record retention period will be automatically extended during 
the course of any unresolved enforcement action regarding the regulated 
activity.

F. Compliance Monitoring and Enforcement for Contingent Management 
Exemptions

    Since contingent management exemptions are self-implementing, the 
Agency needs to rely on its enforcement authorities to ensure that the 
exemptions are being applied in an appropriate manner and that only 
those wastes that are truly nonhazardous are relieved from Subtitle C 
disposal requirements. Compliance monitoring and enforcement of the 
contingent management program would be carried out under existing 
authorities and conditions with which the regulated community should 
already be familiar.
    Claimants must comply with all of the previously described 
conditions of the exemptions to qualify for the exemptions. All persons 
who manage waste for which an exemption has been claimed must manage 
the waste as required under Subtitle C during periods when any of those 
conditions are not met. Claimants that fail to comply with the 
applicable conditions of the contingent management exemption risk 
enforcement action for violations of Subtitle C requirements, including 
administrative, civil and criminal penalties.
1. Compliance Monitoring
    The Agency is proposing that compliance monitoring of the 
contingent management exemption occur through EPA and State oversight, 
primarily through review of notifications and inspections.
    The Agency has the authority, under section 3007 of RCRA, to 
require submission of information and to conduct inspections of 
facilities which EPA has reason to believe may be generating or 
managing a hazardous waste. EPA and States may do confirmatory sampling 
and analysis to determine whether a waste meets the exemption levels. 
Under this authority, the Agency would be able to inspect a non-
Subtitle C facility receiving contingent management exemption waste.
    Inspections of off-site laboratories may also be performed.
2. Enforcement
    The contingent management exemption criteria proposed today would 
create an exit from the Subtitle C system only so long as the 
requirements and conditions established for the exemption are met. 
Failure to comply with any of the conditions for the exemption would 
mean that the wastes would not be exempt from Subtitle C, and the 
claimant could be subject to immediate enforcement action for violation 
of Subtitle C requirements.
    The Agency has the authority under this regulation and RCRA Section 
3007 to require submission of information on the management of exempted 
wastes in a situation where the Agency suspects the claimant has not 
satisfactorily determined whether a waste meets the appropriate 
exemption levels. Alternatively, the Agency may require improved 
analysis using an administrative or civil action under section 3013. 
Failure to manage the contingent management exemption waste in 
accordance with the conditions would void the exemption and the 
conditionally exempt waste would be subject to full Subtitle C 
regulation. The receiving facility, therefore, would become a Subtitle 
C treatment, storage, and/or disposal facility requiring a permit. 

[[Page 66405]]

    In an enforcement action, compliance with the terms and conditions 
of the exemption may be raised as an affirmative defense, but the 
burden will be on the defendant to establish eligibility for the 
exemption and compliance with the conditions necessary to maintain the 
exemption. See 50 FR 642 (Jan. 4, 1985) for a discussion of EPA's 
authority to place such burdens on defendants.
    Claimants may not use the contingent management exemption as a 
means of avoiding enforcement actions. For example, a generator who is 
the subject of an Agency enforcement action cannot claim that the waste 
in question is exempted from Subtitle C under the contingent management 
exemption unless a valid exemption notification for that waste has been 
previously submitted to the Agency and the required documentation to 
support the claim exists at the facility and satisfies the requirements 
of the regulations. The contingent management exemption cannot be used 
in a retroactive fashion to avoid enforcement actions. Similarly, these 
exemptions cannot be used as a legal defense prior to the effective 
date of promulgation of this rule.

G. Exports of Wastes Eligible for Contingent Management Exemptions

    Under option 1A of today's proposal, contingent management 
exemption wastes would remain hazardous until actually disposed of in a 
qualifying unit. The waste would thus remain subject to all applicable 
requirements of 40 CFR parts 262 and 263, including export 
requirements.
     Under option 1B where the waste becomes exempt upon meeting the 
contingent management exit levels, comment is requested on whether 
these exempt wastes should still remain subject to the export 
requirements of 40 CFR part 262. Comment is requested on whether these 
export requirements are necessary to ensure that the contingent 
management exemption waste will be properly managed in the receiving 
country.

H. Land Disposal Restrictions

    As discussed above in section VI, EPA is proposing two approaches 
to integrating LDR requirements with the exit levels for the base 
option. First, EPA is proposing that LDR treatment requirements will 
never apply to wastes that meet exit levels for the base option at the 
point of generation. Second, for wastes which remain subject to LDR 
requirements, EPA is proposing to allow exit levels based solely on the 
combined multipathway and groundwater analyses to serve as alternative 
risk-based LDR standards meeting the ``minimize threat'' standard in 
section 3004(m) of RCRA. EPA believes that both approaches are 
appropriate for contingent management option 1.
    To eliminate the duty to comply with the LDR rules for wastes that 
meet the base option exit level at the point of generation, EPA is 
taking the position that such wastes are defined as hazardous waste 
pursuant to their listing descriptions for such a brief period of time 
that they effectively never become subject to Subtitle C requirements, 
and LDR requirements never apply. It is relatively easy to apply this 
theory to option 1B presented above in section B.2. that allows 
nonwastewaters to exit as soon as they have met the appropriate 
concentration limits and to remain exempt so long as they are managed 
in landfills or monofills. Such wastes need only meet the exit levels 
to obtain their exemption. If they meet them at the point of 
generation, they would appear just as entitled to LDR relief as wastes 
meeting the exit levels for the base option.
    Under option 1A, however, nonwastewaters will not exit until they 
both meet the exit levels and are placed in a landfill or monofill. 
Such wastes would not be eligible for exit at the point of generation 
even if their constituent concentrations were low enough. Rather, they 
would be subject to Subtitle C regulation for a significant portion of 
their ``cradle-to-grave'' management cycle. It would be difficult to 
argue that these wastes had never really been regulated as hazardous 
wastes, and that LDR treatment requirements did not apply. 
Consequently, EPA is not proposing to allow nonwastewaters to become 
exempt from LDR requirements at the point of generation under this sub-
option. EPA requests comment on alternative legal theories that would 
provide a better basis for arguing that nonwastewaters subject to this 
sub-option could be exempt for the LDR rules if they meet exit levels 
at the point of generation.
    Both options 1A and 1B have identical exit levels based on removing 
the predictions for land treatment units and using the next-highest 
concentration as the exit level. EPA is proposing to allow the exit 
levels that are based solely on the multipathway/groundwater risk 
analyses to serve as minimize threat levels for both options 1A and 1B. 
These levels represent concentrations posing minimal low threats for 
nonwastewater placed in landfills, monofills and waste piles. They are 
based on the same risk assessment used for the assessment for the base 
option. They make the same ``reasonable worst case'' assumptions about 
the units' physical setting and the same minimal assumptions about 
control measures. Hence, EPA believes that these exit levels 
sufficiently reduce threats to human health and the environment to meet 
section 3004(m)'s ``minimize threat'' standard.
    EPA acknowledges that option 1B, allowing wastes to exit Subtitle C 
before they are placed in the right kind of land disposal unit, 
presents an additional type of risk. Under option 1B, it may be more 
difficult for EPA to ensure that exited wastes will not be placed in 
land treatment units. (Under the alternative option, option 1A, 
Subtitle C manifest and tracking requirements would apply.) As 
explained above in section B., however, EPA will create conditions for 
option 1B to help ensure that exempted wastes are not disposed of in 
land treatment units. EPA believes that these conditions will 
sufficiently reduce the risk of inappropriate disposal that the exit 
levels will continue to minimize threats. EPA requests comment on this 
aspect of the proposal.

XI. Relationship to Other RCRA Regulatory Programs

    Today's rule proposes specific conditions and exit criteria that 
would exempt listed hazardous wastes, including waste mixtures and 
derived-from wastes, from Subtitle C regulation. Below is a discussion 
of how this proposed rule would affect other relevant RCRA regulatory 
programs.

A. Hazardous Waste Determination

    Under current RCRA regulations, any person who generates a solid 
waste must determine if that waste is a hazardous waste in accordance 
with the procedures outlined in 40 CFR 262.11. According to 262.11, 
generators must first determine if their waste is excluded from 
regulation under 40 CFR 261.4. Generators must then determine if the 
waste is listed in subpart D of part 261. If the waste was not listed, 
or for purposes of compliance with 40 CFR part 268, generators must 
then determine if the waste exhibits a characteristic defined in 
subpart C of part 261.
    Today's proposed rule is an exemption for listed wastes meeting the 
exit criteria, and does not change the general requirements for 
generators making hazardous waste determinations under Sec. 262.11 (see 
discussion of characteristic waste below).

B. Characteristic Hazardous Waste

    Today's proposed rule establishes exemption criteria for hazardous 

[[Page 66406]]
    constituents in eligible listed wastes, waste mixtures, or derived-from 
wastes. If the waste satisfies the exemption criteria proposed today, 
the waste would not be considered listed hazardous waste. However, the 
generator must still determine whether the waste exhibits any 
characteristics of a hazardous waste as specified in 40 CFR 261.21 
through 261.24 and continue to meet hazardous waste requirements if the 
waste does exhibit a characteristic.

C. Toxicity Characteristic Level for Lead

    Toxicity characteristic constituents are among those evaluated for 
exit values in this proposal. In developing the risk assessment for all 
constituents, including the TC constituents, the Agency examined risks 
via groundwater and other pathways to humans, and also environmental 
receptors. In evaluating risks resulting from the groundwater pathway, 
the Agency used its newly developed CMTP model, and the MINTEQ metals 
speciation component. The CMTP model estimates groundwater transport 
using finite source assumptions, and accounting for hydrolysis and 
adsorption of chemicals to soils. The MINTEQ component estimates 
dissolution and speciation of metals in groundwater. Using these 
models, the Agency has developed and is proposing estimates of 
transport through groundwater specific to each constituent. These 
estimates are analogous to constituent-specific dilution and 
attenuation factors (DAFs). These constituent-specific DAFs were 
contemplated for several constituents proposed for regulation in the TC 
rulemaking, but not finalized, because the modeling work was not 
complete. TC levels were set using generic DAFs of 100.
    In developing the constituent-specific DAFs, the Agency estimated 
that lead moves through groundwater much more slowly than predicted by 
the generic DAF of 100. While the modeling analyses supporting the TC 
rule and today's proposed rule are somewhat different from one another, 
the constituent-specific DAF for lead leaching from a landfill was 
estimated as 5000 rather than the 100 used in the TC rule. Higher 
leaching rates (giving lower DAF values) were estimated for some other 
disposal options evaluated in the updated modeling, such as land 
application and management in surface impoundments. This analysis 
raised the question of how the TC and today's proposed rules would 
relate to one another, and whether these results warranted 
consideration of a change to the TC level of 5 mg/l for lead (updated 
groundwater modeling of other TC constituents did not show the large 
disparity between the TC and exit level proposed in today's notice for 
lead).
    In considering these issues, the Agency reviewed several factors. 
First, the human health risk evaluation for lead has changed since the 
TC rule was promulgated, resulting in the MCL (on which the TC is 
based) for lead being reduced from 50 ppb to 15 ppb. Using the new DAF 
from the landfill scenario plus the new drinking water standard could 
raise the TC level to 75 mg/l from the current 5 mg/l. However, when 
lead movement from a land treatment scenario was modeled, a DAF of 
approximately 770 resulted, and a TC level based on this and the new 
drinking water standard could be approximately 10 mg/l. Another 
relevant reference point for lead in the environment includes the 
current OSWER soil direct ingestion level for lead of 400 ppm (as a 
total concentration, not leachate).
    The Agency considered several approaches to potentially proposing 
revisions to the TC level, including basing a new TC level on 
groundwater modeling only, basing it on the soil ingestion estimate, or 
basing it on the driving pathway value and exit level, which considers 
adverse ecologic effects.
    After carefully considering the issue, the Agency concluded that 
the issue of lead toxicity and movement through the environment is very 
complex and changes to existing rules could have significant impacts on 
management of lead-bearing waste and public health. The agency believes 
regulation of lead-bearing wastes warrants careful consideration and 
full evaluation of and review of the policy issues associated with 
considering all potential exposure pathways and risk to human health 
and the environment. Questions include whether the TC level would be a 
leachate or totals value, and whether it would be based on groundwater 
only or other exposure routes and whether it would be human health 
based or based on ecological risk considerations. Such a comprehensive 
evaluation is not feasible in the context of the rulemaking proposed 
today, and so the agency has determined to defer any action on the lead 
TC level. The Agency recognizes that this is an issue of considerable 
interest to the public, and will consider review of management of lead-
bearing waste at the soonest practical time. In the interim, the lead 
TC regulation and the exemption regulation proposed today (when 
finalized) would co-exist as independent regulations.
    As described in Section IV.E.3, the Agency has developed 
groundwater modeling based on both 10,000 year and 1000 year time 
frames. Today's proposal is based on the 10,000 year modeling time 
horizon, and the Agency is soliciting public comment on the alternative 
of using 1000 years. One aspect of the 1000 year modeling results is 
that the groundwater-based exit levels for more constituents would be 
above current TC levels for those constituents. These constituents 
include, in addition to lead, chromium, cadmium, selenium, and mercury. 
The Agency seeks public comment on this aspect of using the 1000 year 
time horizon modeling for risk assessment in the HWIR rule.

D. Hazardous Waste Listings

    The Agency evaluated the likelihood that untreated hazardous wastes 
would be able to meet the exemption criteria in an ``pure'' state 
(e.g., untreated and unmixed) and determined that it is unlikely that 
the constituent concentrations in many untreated hazardous wastes would 
be below today's proposed exemption levels or the applicable BDAT 
standards, particularly for nonwastewaters. Specifically, the Agency's 
hazardous waste characterization data indicate that the concentrations 
of toxicants of concern in untreated listed wastes are typically 
present at levels many times higher than health-based levels or BDAT 
values. Therefore, it is unlikely that the Agency's current criteria 
for listing wastes as hazardous will change as a result of the 
introduction of today's exit criteria into the RCRA regulations. 
However, EPA has been utilizing a more comprehensive risk analysis in 
the listing program, looking at multiple pathways for the movement of 
constituents through the environment, similar to the approach taken in 
today's proposal. Today's proposed approach may also provide the Agency 
with a means of assessing whether or not future listings might 
inadvertently bring into the RCRA system the types of low-concentration 
wastestreams that would subsequently be eligible for exit under today's 
proposal.

E. Delisting

    The evaluation criteria used for delisting may vary from today's 
exemption criteria for various reasons. First, delisting is an 
interactive process that considerable oversight by EPA or authorized 
State agencies. In delisting, the overseeing agency evaluates the 
processes generating a specific wastestream in order to determine the 
constituents likely to be present, as well as the potential variability 
in the waste. 

[[Page 66407]]
EPA (or the State) closely reviews sampling procedures, analytical test 
results, and the accompanying QA/QC data. This oversight increases the 
confidence in the quality and representativeness of the waste analysis.
    Second, delisting is specific to one wastestream, which decreases 
uncertainties that arise in the more generic approach proposed today. 
For example, a delisting petition will typically provide the annual 
generation volume of the waste. Using a specific waste volume as an 
input to various models has allowed EPA to calculate exit levels that 
may be somewhat higher than the levels proposed in today's rule. EPA 
believes that it is reasonable to use higher exit levels for the 
smaller waste volumes in delisting petitions (see 56 FR 32993 (Reynolds 
Metals) for further description of volume impact).
    The delisting process also allows more certainty in the plausible 
management scenarios that are modeled to generate exit levels. For 
example, the characteristics of the waste may dictate the likely 
disposal method (e.g., disposal in a landfill of de-watered process 
sludge). In some cases, special management standards may also be a 
factor (e.g., radioactive wastes are regulated under the Atomic Energy 
Act, therefore if such a hazardous waste were delisted, disposal 
options would be severely limited (see 60 FR 6054 (Hanford delisting)).
    EPA also considers the applicability of available groundwater 
monitoring data from land-based waste management units that have 
received the petitioned waste. Such data are typically required under 
permitting regulations for hazardous waste facilities (see 40 CFR parts 
264 and 265). If any contamination of groundwater appears to be due to 
constituents from the petitioned waste, EPA will consider this as a 
basis to deny the petition. The more generic waste identification rule 
proposed today does not incorporate this additional evaluation 
criterion.
    EPA may also require special testing regimes to ensure waste 
consistently meets delisting criteria (e.g., see (cite Reynolds Metals, 
CSI, Hanford)). Because the overseeing agency reviews the petition in 
some detail, the testing frequency may be closely tied to the potential 
variability of the waste. A facility that accepts and treats waste from 
diverse sources would typically have frequent testing requirements (see 
40 CFR part 261 appendix IX (Envirite)). In other cases, the testing 
requirements for some initial period will be extensive, but the 
subsequent testing may be reduced.
    Delisting petitions for wastes that contain toxic constituents 
which exceed the exemption levels proposed today will continue to be 
accepted and reviewed by the Agency after promulgation of today's rule. 
With the exception of a potentially reduced petition review burden, the 
Agency does not anticipate any changes in the current review of 
delisting petitions as a result of the implementation of today's 
proposed exemption. EPA does request comment on which risk models 
should be used to evaluate future delisting petitions.

F. Requirements for Treatment, Storage, and Disposal Facilities and 
Interim Status Facilities

    In order to implement the changes proposed today, owners or 
operators of RCRA permitted or interim status facilities may have to 
amend their waste analysis plans if required under 40 CFR 264.13 and 
265.13. Such changes will most likely include the addition of the 
appropriate analysis methods and changes that may be required in the 
frequency of testing.
    Permitted facilities, in unauthorized States, who elect to employ 
the exemption procedures and who subsequently prepare changes to their 
waste analysis plans should, following promulgation of this rule, 
submit a Class I permit modification to EPA. (EPA is aware that 
although most States have either become authorized for, or have 
adopted, the 3-class permit modification regulations, some states may 
still be operating under the older ``major/minor'' permit modification 
procedures. Under those procedures, changes to the waste analysis plan 
would be considered a major modification).

G. Closure

    Under today's proposed rule, a hazardous waste management unit that 
receives wastes that are exempt under today's exit criteria would 
continue to be a regulated Subtitle C unit subject to the requirements 
of 40 CFR parts 264 or 265, including closure requirements, until the 
owner/operator completed clean closure of the unit or unless all of the 
waste in the unit were delisted. A unit receiving only waste that is 
exempt under today's proposal would no longer be receiving hazardous 
waste upon the effective date of the exemption; such a unit would 
normally become subject to Subtitle C closure requirements, which are 
triggered by the final receipt of hazardous waste by the unit. The 
facility owner or operator is required to complete closure activities 
within 180 days after receiving the final volume of hazardous waste. 40 
CFR 264.113(b) and 265.113(b). However, RCRA closure requirements do 
allow certain waste management units to delay closure, while continuing 
to receive non-hazardous waste (such as waste exempt under today's 
proposed rule), provided certain conditions are met.
    The RCRA delay-of-closure regulations, promulgated on August 14, 
1989 (54 FR 33376), allow owners or operators to delay the closure of 
landfills, land treatment units, and surface impoundments in cases 
where the unit stops receiving hazardous waste but the owner or 
operator wishes to continue using the unit to manage only non-hazardous 
waste. These requirements are outlined in 40 CFR 264.113(d) and (e) and 
265.113(d) and (e). Owners or operators wishing to delay closure must 
request a permit modification at least 120 days prior to final receipt 
of hazardous wastes, or, if the facility is in interim status, submit 
an amended part B application at least 180 days prior to the final 
receipt of hazardous wastes. The request for a permit modification or 
the amended part B application must include demonstrations that the 
unit has the existing design capacity to manage non-hazardous wastes, 
and that the non-hazardous wastes are not incompatible with any wastes 
in the unit. In addition, certain facility information including the 
waste analysis plan, groundwater monitoring plans, closure and post-
closure plans, cost estimates, and financial assurance demonstrations 
must be updated as necessary to account for receipt of only non-
hazardous waste. Sections 264.113(d) and 265.113(d). In addition, 
surface impoundments that do not meet the minimum technological 
requirements (MTRs) for liners and leachate collection of RCRA 3004(o) 
must comply with additional requirements in order to delay closure, 
including the removal of hazardous wastes to the extent practicable 
from the unit. Sections 264.113(e) and 265.113(e).
    The delay of closure regulations apply only to landfills, land 
treatment units, and surface impoundments. In the case of other RCRA 
units such as tanks and waste piles, the Agency did not feel that the 
delay-of-closure regulations were necessary for these types of units in 
order to receive only non-hazardous wastes (54 FR 33383). The closure 
requirements in subpart G for these units include removal or 
decontamination of waste residues, containers, liners, bases and 
contaminated soils, equipment, and other containment system components; 
these closure requirements are not incompatible with the reuse of these 


[[Page 66408]]
units for receipt of only non-hazardous waste. Once the unit has been 
emptied of all hazardous wastes and decontaminated, it could receive 
non-hazardous waste. However, the Agency also recognizes that some 
flexibility may be warranted in converting the use of a unit such as a 
tank from hazardous to non-hazardous waste management. EPA solicits 
comment on whether an owner or operator might demonstrate removal of 
hazardous waste residues from the tank by demonstrating that all waste 
in the tank is below exemption levels, without removing the waste from 
the tank. In cases where the owner or operator could not demonstrate 
that all wastes in the tank were below exemption levels, he or she 
would have to remove the hazardous waste in order to achieve closure of 
the unit. In some cases, the facility owner or operator may be able to 
demonstrate that a tank no longer managed hazardous waste (because the 
waste met today's proposed exemption criteria), but did not achieve 
clean closure because of soil and perhaps groundwater contamination. In 
this case, EPA solicits comment on whether the facility owner or 
operator should be required to remove the contamination to clean 
closure levels, or close the area as a landfill while using the tank to 
manage nonhazardous wastes, as long as this activity did not interfere 
with cleanup activities or control of the contaminated areas.
    The Agency also believes that the availability of a delay-of-
closure option provides much of the flexibility needed to allow for the 
uninterrupted management of exempt waste, while providing assurance 
that the protections afforded by the closure regulations for Subtitle C 
units (e.g., evaluation of soil and groundwater at closure) are not 
lost. This approach makes sense in light of the fact that today's 
proposed exemption is self-implementing, which the Agency feels is 
appropriate for waste identification purposes, but not necessarily so 
for determining whether a Subtitle C unit may become a Subtitle D unit 
without first undergoing closure.

H. HWIR-Media Rule/Subtitle C Corrective Action

    The Agency is currently planning on proposing a rule (``HWIR 
Media'') addressing waste management issues relating to environmental 
media (e.g., soil, groundwater, and sediments). The goal of this rule 
is to allow more effective cleanups at contaminated sites. As currently 
drafted, the media proposal will supplement the regulatory system under 
RCRA for the management of RCRA hazardous contaminated media, 
applicable to sites that are undergoing cleanup overseen by EPA or 
authorized States. Such sites include cleanups at RCRA corrective 
action sites, State cleanups, and Superfund remedial actions. The media 
rule will propose a ``bright-line'' distinction between hazardous 
contaminated media (i.e., media containing hazardous waste that is 
therefore regulated as hazardous) subject to modified Subtitle C 
standards, and less contaminated media subject to more site-specific, 
flexible standards implemented by State agencies. This new system will 
supplement the current approach(es) to identifying RCRA applicability 
to the management of contaminated media. The rule will also propose 
streamlined permit requirements for cleanups. It will not specify 
cleanup standards.
    Today's proposal applies to listed hazardous wastes (e.g. process 
wastes, sludges, discarded commercial chemical products, etc.), 
including mixtures of one or more listed wastes with other solid 
wastes, and residues derived from the treatment, storage, or disposal 
of one or more listed hazardous wastes. Media that contain listed 
hazardous wastes, mixtures, or derived-from wastes with constituent 
concentrations below today's proposed exemption levels will be eligible 
for exemption under the procedures proposed today. EPA or an authorized 
State may continue to assess contaminated media with concentrations 
higher or lower than the exit levels proposed today on a case-by-case 
basis by making site-specific determinations as to whether a media 
``contains'' a RCRA hazardous waste.

I. Land Disposal Restriction Program

    Today's rule contains several important areas of overlap with the 
RCRA Land Disposal Restrictions (LDR) program that are discussed 
elsewhere in today's rule. First, as described in more detail elsewhere 
in this notice, EPA is proposing that exit levels produced under the 
multipathway analysis for constituents with adequate analytical methods 
should ``cap'' existing technology-based LDR standards, where the exit 
levels are less stringent than the current LDR values. If a waste 
contains only constituent with ``capped'' LDR values, it should be able 
to satisfy LDR requirements and exit Subtitle C for all other purposes 
as soon as the waste achieved those levels.
    Under today's proposal the uncapped LDR requirements for listed 
hazardous wastes continue to apply to a waste even after the waste 
becomes exempt from Subtitle C under the exemption criteria. 
Furthermore, for listed wastes containing certain constituents with 
analytical problems, compliance with the LDRs (either numerical levels, 
specified treatment, or both) is part of the criteria for exempting 
that waste under today's proposal. Specifically, for constituents where 
there are no adequate analytical methods for determining whether or not 
the exit levels have been met, a combination of meeting applicable LDR 
standards and a showing of non-detect estimated quantitation 
concentration is required to satisfy the exit criteria for these 
constituents. This is explained in more detail in Section IV.I of 
today's rule.
    If, however, a listed waste is below the exit concentrations 
proposed today at the point where the waste is ``first'' generated, 
that is, the point where the waste first meets the listing description 
and is potentially subject to Subtitle C, then a hazardous waste is 
never really ``generated'' and the LDR requirements do not attach to 
the waste. The EPA does not expect many listed wastes to be at or below 
the exit criteria at the point of first generation, where waste 
characterization data indicate that this is where wastes contain higher 
concentrations of hazardous constituents. Nonetheless, where a 
particular process generates a waste that is perhaps inappropriately 
captured by a listing, or where pollution prevention efforts by the 
generator result in a waste of lower constituent concentrations, if the 
waste meets the exemption criteria at the moment it is first generated, 
the LDR requirements would not apply. In contrast, once a listed waste 
is generated and managed the LDR requirements attach, and remain even 
after the waste exits Subtitle C under today's exemption (unless, as 
stated, where the exit levels are considered equivalent to a minimize 
threat standard). This issue is discussed in more detail in Section VI 
in today's proposal.
    It should be noted that the Agency is currently reviewing the 
definition of ``point-of-generation'' with respect to the application 
of the LDRs. Since November 1986 (51 FR 40620), EPA has required LDR 
determinations to be made at the point which hazardous wastes are 
generated. In the Phase III LDR rule (March 2, 1995, 60 FR 11702), EPA 
solicited comment on the issue of where the point of generation should 
be defined. EPA presented three options to narrowly redefine the point 
at which the land disposal prohibitions attach: (1) Similar 
wastestreams generated by similar processes, (2) wastestreams from a 
single process, and (3) ``battery limits.'' With Option 1 the point of 
generation would be defined at the point after which like wastestreams 
are generated from like processes and combined as a matter of routine 

[[Page 66409]]
practice. Option 2 would consider the point of generation to occur when 
wastestreams from a single process are combined (e.g., residual 
wastestreams collected in a common unit such as a sump). In many cases, 
these wastestreams are similar in composition because they all come 
from a common unit process. The Option 3 ``battery limits,'' is similar 
to Option 2; however instead of limiting aggregation to that normally 
occurring within a single unit process, the facility would view an 
entire battery of processes (associated with making a single product or 
related group of products) as a single manufacturing step. In the Phase 
III LDR proposal, EPA identified listed hazardous wastes as situations 
where existing point of generation determinations may remain 
appropriate. This is because EPA has carefully reviewed the various 
waste streams and has defined the point of generation as part of the 
listing description. Therefore, it may be inappropriate to modify that 
description with a more generic ``point of prohibition'' rule. This is 
important because today's rule applies only to listed hazardous wastes.
    Lastly, under today's proposal, mixtures containing listed 
hazardous waste and residues from the treatment, storage, or disposal 
of listed hazardous waste that contain some constituents with 
concentrations below exit levels and some constituents with 
concentrations above exit levels would continue to be managed as listed 
hazardous wastes. Today's notice does not allow for partial exemptions, 
because the Agency does not believe that a self-implemented exemption 
process is well suited to partial exemptions. It is not always clear 
what the origin of a hazardous constituent is, particularly for 
constituents that are formed as by-products of treatment or waste 
interactions. Further, the proposed exemption criteria are not waste-
specific, and thus are not suited to waste-specific or partial 
exemptions. Thus, the determination that a waste that carries two 
listing numbers should no longer bear one of the listing numbers is not 
always a straight-forward decision. The Agency has designed the 
exemption process proposed today to remove as much subjective decision 
making from the process as possible.
    However, while the Agency is not today proposing an alternative 
that would allow these wastes to use only the hazardous waste codes for 
those listed wastes that are the origin of the constituents above the 
exit levels, the Agency believes that there could be merit in the 
concept for a future proposed rulemaking should the implementation 
concerns stated above be overcome. Therefore, the Agency requests 
information on actual cases with waste characterization data where a 
waste bears more than one waste code which results in conflicting 
treatment standards under the land disposal restrictions rules. If the 
Agency finds that there is a serious compliance issue for multiple 
listing wastes, the Agency may reconsider this decision, as well as 
other potential solutions to any documented problems.

J. RCRA Air Emission Standards

    Today's proposed rule, when promulgated, may have an impact on the 
effectiveness of two other RCRA rules developed by the Agency under 
HSWA authority. Section 3004(n) of HSWA directed the Agency to 
promulgate regulations controlling air emissions from hazardous waste 
TSDFs ``as necessary to protect human health and the environment.'' 
Subsequent Agency analysis demonstrated that air emissions from TSDFs 
do pose substantial risk in the absence of controls, and that controls 
were therefore required under the HSWA mandate. The Agency is 
fulfilling this mandate in phases; EPA completed the first phase when 
it promulgated RCRA air standards that control organic emissions vented 
from certain hazardous waste treatment processes, as well as from leaks 
in certain ancillary equipment used for hazardous waste management 
processes (55 FR 25454, June 21, 1990; 40 CFR part 264/265, subparts AA 
and BB). More recently, EPA completed the second phase when it 
promulgated RCRA air standards for tanks, surface impoundments, 
containers, and miscellaneous units operated at TSDFs (59 FR 62896, 
December 6, 1994; 40 CFR part 264/265, subpart CC). Together, these 
rules would reduce the risk from air emissions from the vast majority 
of these facilities to well within the risk range of other RCRA 
standards. After more thorough analysis, the Agency may issue a third 
phase of these regulations to address any residual risk. The emission 
reductions achieved by these rules would also significantly reduce the 
formation of ozone, which has adverse effects on human health and the 
environment.
    Hazardous waste that satisfies the exemption criteria proposed 
today (including any constituent-specific exit concentrations for 
volatile organic chemicals, or VOCs), would be exempt from Subtitle C 
regulations, including regulations promulgated to date under RCRA 
3004(n). In other words, once a waste is no longer regulated as 
hazardous, any unit in which the waste is managed (assuming no other 
hazardous wastes are being/have been managed in the unit) is not 
subject to Subtitle C regulations, including 40 CFR parts 264 and 265, 
subparts AA, BB, and CC. However, the Agency believes that it is 
important to ensure that the risks associated with air emissions both 
from hazardous wastes, and from wastes that would be eligible for exit 
under today's proposal, are adequately addressed. In the final rule 
establishing air emission controls for tanks, surface impoundments, 
containers, and miscellaneous units (the ``Subpart CC'' rule), the 
Agency established a threshold level of 100 ppmw (parts per million by 
weight) for total volatile organics in a waste, a concentration which 
if equaled or exceeded that would trigger the emission control 
requirements for these units. Because there are examples of exit levels 
proposed today for specific volatile organic constituents that exceed 
this 100 ppmw threshold, the Agency considered whether today's exit 
levels adequately addressed the air emission concerns of 3004(n) in 
allowing waste to exit Subtitle C. There are important differences in 
the underlying risk modeling between the two rules. However, the Agency 
believes that the constituent-specific risk evaluation done for this 
rulemaking results in proposed exit levels that for VOCs will not be 
less protective than the standards established to date under RCRA 
3004(n). Despite these differences, the Agency requests comment on 
whether or not a total VOC concentration of 100 ppmw (parts per million 
weight), which is the concentration that triggers air emission controls 
under the Subpart CC rule, would be appropriate for use in the exit 
rule proposed today, and if so, how this level would be used.

K. Hazardous Debris

    Hazardous debris that contains one or more listed hazardous wastes 
is eligible for exiting Subtitle C under today's proposed rule. The EPA 
notes, however, that certain exemptions already exist relating to 
hazardous debris. On August 18, 1992, the EPA published a final rule on 
the Land Disposal Restrictions for Newly Listed Wastes and Hazardous 
Debris (57 FR 37194). In that rule, EPA required that hazardous debris 
be treated prior to land disposal, using specified treatment 
technologies from the treatment categories of extraction, destruction, 
or immobilization. (See 40 CFR 268.45, Table 1.) EPA also added a 
conditional exemption at Sec. 261.3(f) for non-characteristic hazardous 
debris (i.e., 

[[Page 66410]]
debris that is hazardous solely because it contains one or more listed 
hazardous wastes). Section 261.3(f)(1) exempts debris from Subtitle C 
regulation provided that the debris is treated using one of the 
extraction or destruction technologies specified in Table 1 of 
Sec. 268.45. Alternatively, non-characteristic hazardous debris can be 
exempt under Sec. 261.3(f)(2) if it is determined to be no longer 
hazardous by the Regional Administrator, after considering the extent 
of contamination of the debris, i.e., after a ``contained-in'' 
determination is made. However, non-characteristic hazardous debris 
contaminated with a listed waste, that is treated by a specified 
immobilization technology is not eligible for the conditional exemption 
in Sec. 261.3(f)(1), and therefore remains subject to Subtitle C 
regulation after treatment.
    In today's rule, EPA is not proposing to change the current 
exemption under Sec. 261.3(f); therefore, non-characteristic hazardous 
debris that requires LDR treatment by extraction or destruction 
technologies will be exempt from Subtitle C regulation, once treated. 
As was explained more thoroughly in the final rule for hazardous 
debris, the Agency gave careful consideration to many factors before 
exempting certain treated debris, including whether each debris/
contaminant type would be effectively treated by each BDAT technology 
to levels that would no longer pose a hazard to human health or the 
environment (57 FR 37240). However, hazardous debris that contains 
listed waste, and for which immobilization is the specified LDR 
treatment, may exit using today's proposed exit criteria. See also the 
discussion of a contingent management option above for a description of 
an alternative for encapsulated debris contaminated by radioactive 
``mixed'' hazardous wastes. Finally, EPA is not proposing to change the 
contained-in exemption under Sec. 261.3(f)(2) for hazardous debris; 
that is, the Regional Administrator may continue to determine on a 
case-by-case basis that hazardous debris no longer contains listed 
hazardous waste, and should therefore be exempt from RCRA Subtitle C.

L. Hazardous Wastes Used in a Manner Constituting Disposal

    Section 266.20 (b) of the regulations states that hazardous wastes 
and hazardous waste-derived products that are legitimately recycled by 
being applied to or placed on the land are largely exempt from subtitle 
C regulation provided they satisfy three conditions: the recyclable 
materials must have undergone a chemical reaction so as not to be 
separable by physical means, the product must be produced for the 
general public's use, and land disposal restriction treatment standards 
for every hazardous waste in the hazardous waste-derived product must 
be satisfied. (The shorthand for this type of recycling is ``use in a 
manner constituting disposal''. See Sec. 261.2(c)(1).) EPA developed 
Sec. 266.20(b) largely as a stop-gap to provide some modicum of safety 
while EPA studied further whether various disposal-like uses of 
hazardous waste-derived products in fact were safe or warranted 
control. 50 FR 614, 628-29, 647 (Jan,. 4, 1985). Since then, the Agency 
has studied particular use constituting disposal practices and 
determined, or proposed, that such uses either be prohibited or allowed 
based on more individualized determinations of risk. See 53 FR 31138, 
31164 (August 17, 1988) (allowing use of fertilizers derived from waste 
K 061 because of similarity to other zinc-containing fertilizers); 59 
FR 43496, 43500 (August 24, 1994) (prohibiting anti-skid uses of K 061-
derived sags); 59 FR 67256 (Dec. 29, 1994) (proposing to allow certain 
uses of K 061 if risk-based criteria are satisfied); 60 FR 11702, 11732 
(March 2, 1995) (proposing to prohibit hazardous waste use as fill 
material).
    EPA solicits comment today on the relationship of today's proposed 
exit levels and the general use constituting disposal provisions in 
Sec. 266.20(b) stating that such uses can occur if land disposal 
restriction treatment standards are satisfied. These land disposal 
restriction standards are not fully protective in all cases: the 
standards are technology-based rather than risk-based, and, for metal 
hazardous constituents, only control leachable amounts of the metal. 
Yet in many situations, total metal levels, rather than leachable 
levels, will be the critical factor because of the possibilities of 
direct contact through inhalation of abraded or wind-dispersed 
contaminants, or surface runoff. These exposure pathways are critical 
for uses constituting disposal because the hazardous waste are not 
placed in a confined unit. 60 FR at 11733, 59 FR at 43499.
    The exit levels proposed today, on the other hand, are risk-based 
(although some are capped by quantitation limits), are expressed as 
both total and leachable concentrations, and consider exposure pathways 
in some cases similar to those relevant in analyzing uses constituting 
disposal. The Agency solicits comment as to the appropriateness of 
applying these levels to hazardous wastes used in a manner constituting 
disposal (or at least to those uses where the hazardous waste-derived 
products are not comparable to non-hazardous waste based products that 
would be used in their place). One approach would be to replace the 
requirement to meet LDR treatment standards with a requirement to meet 
the exit levels proposed today. This approach should assure that exit 
levels for unconfined hazardous wastes (i.e. hazardous wastes used in a 
manner constituting disposal) are never less stringent than exit levels 
for hazardous wastes placed in confined units. EPA believes that the 
risk assessment it conducted for the exit levels considered scenarios 
sufficiently similar to use constituting disposal scenarios to ensure 
that the exit levels would be reasonably protective for uses (and more 
protective than LDR levels, in many cases, because of the analysis of 
impacts from total concentrations of constituents). EPA, however, 
requests comment on the reasonableness of this approach.
    Another option would be to require persons wishing to use hazardous 
wastes in a manner constituting disposal to meet the lower of the LDR 
treatment standards and the exit levels. Because EPA is today proposing 
setting exit levels for both total and leachable concentrations, and 
because LDR standards are expressed as either total or leachable 
levels, however, EPA is not certain how to meaningfully compare 
relative stringency.
    With respect to the current requirement in Sec. 266.20(b) that 
persons wishing to use waste in a manner constituting disposal meet the 
treatment standards from the LDR program, EPA notes that compliance 
with LDR tracking and recordkeeping rules is not required. EPA proposes 
today to require compliance only with the exit levels where they 
substitute for LDR treatment levels, although it requests comment on 
the option of requiring persons using wastes in this manner also to 
file the exit notification package proposed today. EPA does not intend 
that such persons be required to comply with conditions that continue 
to apply after exit, such as periodic retesting.
    Finally, EPA proposes to eliminate the requirement that wastes to 
be used in a manner constituting disposal undergo a chemical reaction 
so as to be inseparable by physical means. EPA does not believe it is 
necessary to retain this requirement since wastes will be evaluated for 
total constituent concentrations. (EPA, however, will retain this 
requirement for wastes with treatment standards expressed as a 
specified technology, rather than concentration levels.) 

[[Page 66411]]

    Were EPA to proceed on this course, the Agency would adjust the 
timing of any regulatory action so that it does not supersede the 
separate rulemaking the Agency is now conducting on certain uses of 
residues derived from K 061 recovery facilities. 59 FR 67256. Thus, the 
Agency does not intend to take final action affecting these uses until 
the analysis begun in that rulemaking is completed on the schedule 
established in that rulemaking.
    With respect to the other pending proposal, involving a prohibition 
on placement of hazardous waste as fill material, the Agency requests 
comment on whether it should substitute permission to use waste that 
has met the proposed exit levels for the proposed prohibition. The risk 
assessment underlying today's proposal addressed the major pathways 
that would arise from use as fill, but may not have used input values 
that fully reflect the fill scenario for some important parameters. For 
example, unit depths may be greater for fill sites than for land 
application units. At the same time, use of hazardous waste as fill is 
a proven cause of human health and environmental harm, contributing 
significantly to a number of Superfund sites. See Docket F-95-PH3P-
FFFFF (record for the pending proposal). In light of this, the Agency 
questions whether to substitute today's proposed exit approach for the 
proposed prohibition.

XII. CERCLA Impacts

    All listed hazardous wastes are listed as hazardous substances 
under section 101(14)(C) of the Comprehensive Environmental Response, 
Compensation, and Liability Act (CERCLA) of 1980, as amended. Under 
section 103(a) of CERCLA, notification must be made to the Federal 
government of a release of any CERCLA hazardous substance in an amount 
equal to or greater than the reportable quantity (RQ) assigned to that 
substance within a 24 hour period. (See 40 CFR part 302 for a list of 
CERCLA hazardous substances and their Rqs.) If a specific waste from a 
particular facility meets the exemption criterion in this rule, the 
waste is not a listed hazardous waste and therefore not a hazardous 
substance by virtue of its hazardous waste listing. Thus, notification 
under CERCLA of a release of the exempted waste may not be necessary. 
In this situation, CERCLA notification of releases of the waste would 
only be required if the waste or any of the constituents of the waste 
are CERCLA hazardous substances by virtue of Section 101(14) (A), (B), 
(D), (E), or (F) of CERCLA or 40 CFR 302.4(b), and are released in 
amounts greater than or equal to their Rqs. The Agency requests comment 
on this approach.
    Exit levels also may be applicable to the CERCLA program where it 
has been documented that RCRA listed hazardous waste has been disposed 
of at the site. Section 121(d) of CERCLA, as amended by the Superfund 
Amendments and Reauthorization Act (SARA) of 1986, requires that CERCLA 
actions comply with, or justify a waiver of, applicable or relevant and 
appropriate requirements (ARARs) under federal and state environmental 
laws. The options proposed in this rule would determine the legal 
applicability of federal RCRA managements requirements to remediation 
wastes generated at Superfund sites. They may also be considered in 
determining whether RCRA is relevant and appropriate in cases where it 
is not applicable.
    At sites undergoing CERCLA remedial activities where no listed 
hazardous wastes have been identified, the Agency will generally use a 
site-specific risk assessment for all chemicals for which there are no 
ARARs. In some cases, these health-based cleanup levels will be higher 
than the exemption levels, based on a reasonably conservative exposure 
scenario which does not include leachate ingestion. In other cases, the 
CERCLA health-based clean-up levels will be lower than exemption levels 
when additive effects are considered or when specialized analytical 
techniques are required in order to lower quantitation limits. The 
CERCLA health-based clean-up levels may also be different than 
exemption levels based on the consideration of site-specific factors.

XIII. State Authority

A. Applicability of Rules in Authorized States

    Under section 3006 of RCRA, EPA may authorize qualified States to 
administer and enforce the RCRA program within the State. (See 40 CFR 
part 271 for the standards and requirements for authorization.) 
Following authorization, EPA retains enforcement authority under 
sections 3008, 7003, and 3013 of RCRA, although authorized States have 
primary enforcement responsibility.
    Prior to the Hazardous and Solid Waste Amendments (HSWA) of 1984, a 
State with final authorization administered its hazardous waste program 
entirely in lieu of EPA administering the Federal program in that 
State. The Federal requirements no longer applied in the authorized 
State and EPA could not issue permits for any facility in the State 
that the State was authorized to permit. When new, more stringent 
Federal requirements were promulgated or enacted, the State was obliged 
to enact equivalent authority within specified time frames. New Federal 
requirements did not take effect in an authorized State until the State 
adopted the requirements as State law.
    In contrast, under section 3006(g) of RCRA, 42 U.S.C. 6926(g), new 
requirements and prohibitions imposed by the HSWA take effect in 
authorized States at the same time that they take effect in non-
authorized States. EPA is directed to implement HSWA requirements and 
prohibitions in an authorized State, including the issuance of permits, 
until the State is granted authorization to do so. While States must 
still adopt HSWA-related provisions as State law to retain final 
authorization, HSWA applies in authorized States in the interim.

B. Effect of State Authorizations

    Today's proposal, if finalized, will promulgate regulations that 
are not effective under HSWA in authorized States. Thus, the exemption 
will be applicable only in those States that do not have final 
authorization.
    Authorized States are only required to modify their programs when 
EPA promulgates Federal regulations that are more stringent or broader 
in scope than the authorized State regulations. For those changes that 
are less stringent or reduce the scope of the Federal program, States 
are not required to modify their programs. This is a result of section 
3009 of RCRA, which allows States to impose more stringent regulations 
than the Federal program. Today's proposal for exit levels is 
considered to be less stringent than, or a reduction in the scope of, 
the existing Federal regulations because it would exempt certain wastes 
now subject to RCRA Subtitle C. Therefore, authorized States are not 
required to modify their programs to adopt regulations consistent with 
and equivalent to today's proposal.
    Even though States are not required to adopt most options in 
today's proposal, EPA strongly encourages States to do so as quickly as 
possible. As already explained in this preamble, today's proposal will 
reduce over-regulation of dilute wastes and will provide an alternative 
to delisting. States are therefore urged to consider the adoption of 
today's proposal (when promulgated); EPA will expedite review of 
authorized State program revision applications.

C. Streamlining Issues

    EPA is considering a new approach to state authorization for rules 
revising the 

[[Page 66412]]
RCRA program. Under this new approach EPA would vary the requirements 
for state submissions and for EPA's review to reflect differences in 
the scope and complexity of various program revisions. This 
differential approach to authorization also would recognize the fact 
that many states now have more than a decade of experience in 
implementing large portions of the RCRA program and commensurate 
experience in obtaining authorization for program revisions. EPA 
believes that adjusting authorization requirements will strike an 
appropriate balance between recognizing state experience and ensuring 
environmental protection.
    EPA recently proposed a greatly streamlined set of procedures for 
the least complex changes to the LDR program in the ``LDR Phase IV'' 
rulemaking. EPA, however, proposed to retain the current authorization 
process for other portions of the rule that presented more complex and 
novel regulations.
    EPA is also developing a different approach to streamlining 
authorization for the ``HWIR media'' proposal scheduled for publication 
later in 1995. Although EPA expects some aspects of these state 
authorization procedures to be unique to the HWIR- media rulemaking, 
EPA will determine whether some of the concepts can be used to craft 
streamlined procedures for additional RCRA rules.
    EPA was not able to develop a streamlined authorization process for 
this rule in time to include it in this proposal. EPA, however, intends 
to describe such a process in more detail in the preamble to the 
proposed HWIR-media rule. EPA anticipates that most elements of the 
basic waste exit scheme proposed in today's notice would be eligible 
for a greatly streamlined approach to authorization. For example, the 
new LDR standards based on ``minimize threat'' findings would be good 
candidates for streamlined authorization because states that are 
already authorized for significant portions of the LDR program are 
familiar with the type of rule changes needed, have adopted all or most 
of the underlying LDR program, and have experience in implementing and 
enforcing the rules. The exit levels, along with the self-implementing 
approach to exit determinations, are also likely to be eligible for a 
greatly streamlined approach. The scheme is very similar to the 
existing program for determining whether a waste exhibits any of the 
hazardous waste characteristics, particularly the 1980 EP Toxicity 
Characteristic and the expanded 1990 Toxicity Characteristic. Under 
both the characteristic rules and today's proposal, generators are 
responsible for determining whether or not a waste meets a numerical 
definition of ``hazard''. States must then enforce by reviewing records 
of determinations and/or conducting their own analysis of wastes 
determined not to be hazardous. Consequently, States which have been 
authorized for the base program already have experience in adopting and 
enforcing rules which resemble the exit scheme proposed today. EPA, 
however, notes that adopting the exit scheme proposed in today's notice 
will place additional demands on state inspection and enforcement 
resources. EPA will give careful consideration to balancing the need to 
ensure that a state has sufficient resources to implement an exit 
program with the goal of streamlining the authorization process.
    Today's scheme does differ from the original characteristics and 
the 1990 Toxicity Characteristic by including some requirements which 
must be enforced as conditions of exit. These requirements, however, 
are requirements for testing, notification and recordkeeping that are 
relatively easy to meet and relatively easy to detect if violated. 
Accordingly, EPA does not at this time anticipate that these conditions 
would require it to retain the current authorization process.
    EPA currently finds it unlikely that it will propose a greatly 
streamlined authorization process for any of the contingent management 
options presented for discussion in today's proposal. These options 
will raise novel legal, implementation and enforcement issues. A more 
conventional approach to the review of state authorities and 
capabilities may be warranted. If EPA proposes any of these options in 
the future, it will consider the possibility of adapting the approach 
to authorization that it is currently developing for the HWIR-media 
proposal.

XIV. Regulatory Requirements

A. Analytical Requirements

1. Executive Order 12866
    Under Executive Order 12866, (58 FR 51735 (October 4, 1993)) the 
Agency must determine whether this regulatory action is 
``significant.'' A determination of significance will subject this 
action to full OMB review and compliance under Executive Order 12866 
requirements. The order defines ``significant regulatory action'' as 
one that is likely to result in a rule that may:
    (a) Have an annual effect on the economy of $100 million or more, 
adversely affect in a material way the economy, a sector of the 
economy, productivity, competition, jobs, the environment, public 
health or safety, or state, local, or tribal governments or 
communities;
    (b) Create a serious inconsistency or otherwise interfere with an 
action taken or planned by another agency;
    (c) Materially alter the budgetary impact of entitlement, grants, 
user fees, or loan programs, or the rights and obligations of 
recipients thereof; or
    (d) Raise novel legal or policy issues arising out of legal 
mandates, the President's priorities, or the principles set forth in 
the terms of the Executive Order.
    The proposed rule is expected to have an annual effect on the 
economy greater than $100 million. Furthermore, although voluntary, the 
adoption of this action may burden state or tribal governments with 
increased regulatory review requirements. Today's action may also raise 
novel legal or policy issues as they relate to the President's 
priorities for environmental protection within a regulatory system 
facing resource limitations. The Agency, therefore, has determined that 
today's proposed rule is a ``significant regulatory action.'' As a 
result, this rulemaking action, and supporting analyses, are subject to 
full OMB review under the requirements of the Executive Order. The 
Agency has prepared an Assessment of The Potential Costs and Benefits 
of The Hazardous Waste Identification Rule for Industrial Process 
Wastes, as Proposed, in support of today's action. A summary of this 
Assessment and findings is presented in section D below.
2. Regulatory Flexibility Analysis
    Pursuant to the Regulatory Flexibility Act of 1980, 5 U.S.C. 601 et 
seq., when an agency publishes a notice of rulemaking, for a rule that 
will have a significant effect on a substantial number of small 
entities, the agency must prepare and make available for public comment 
a regulatory flexibility analysis. This analysis shall consider the 
effect of the rule on small entities (i.e.: Small business, small 
organizations, and small governmental jurisdictions).
    Under the Agency's revised Guidelines for Implementing the 
Regulatory Flexibility Act, dated May 4, 1992, the Agency committed to 
considering regulatory alternatives in rulemakings when there were any 
economic impacts estimated on any small entities. Previous guidance 
required alternatives to be examined only when significant economic 
effects were estimated for a substantial number of small entities. The 
Agency has 

[[Page 66413]]
prepared a Regulatory Flexibility Analysis in support of today's 
action. A summary of this analysis and findings is presented in section 
E below.
3. Environmental Justice
    Executive Order 12898, ``Federal Actions to Address Environmental 
Justice in Minority Populations and Low-Income Populations,'' directs 
each Federal Agency to ``make achieving environmental justice part of 
its mission by identifying and addressing, as appropriate, 
disproportionately high and adverse human health and environmental 
effects of its programs, policies, and activities on minority 
populations and low-income populations * * *''
    The Executive Order requires that where environmental justice 
concerns or the potential for concerns are identified, appropriate 
analysis of the issue(s) be evaluated. To the extent practicable, the 
ecological, human health (taking into account subsistence patterns and 
sensitive populations) and socio-economic impacts of the proposed 
decision-document in minority and low-income communities should also be 
evaluated.
    The Agency has examined Environmental Justice concerns relevant to 
today's action. A summary of this analysis and findings is presented in 
section F below.
4. Paperwork Reduction Act
    The information collection requirements in this proposed rule have 
been submitted for approval to the Office of Management and Budget 
(OMB) under the Paperwork Reduction Act, 44 U.S.C. 3501 et seq. An 
Information Collection Request (ICR) document has been prepared by EPA 
(ICR No. 1766.01) and a copy may be obtained from Sandy Farmer, OPPE 
Regulatory Information Division; U.S. Environmental Protection Agency 
(2137); 401 M St., SW.; Washington, DC 20460 or by calling (202) 260-
2740.
    This information collection is required to provide documentation of 
solid waste exemptions from Subtitle C requirements, and will allow for 
certification and verification as the program evolves. Exemptions under 
today's action require no formal preapproval. As such, information 
collection, maintenance and reporting issues are especially important 
due to the self-implementing nature of this action. Successful 
implementation of today's proposal will depend upon the documentation, 
certification, and verification provided by the information collection.
    The general authority for this proposal is sections 2002(a), 3001, 
3002, 3004, and 3006 of the Solid Waste Disposal Act of 1970, as 
amended by the Resource Conservation and Recovery Act of 1976 (RCRA), 
as amended by the Hazardous and Solid Waste Amendments of 1984 (HSWA), 
42 U.S.C. 6912(a), 6921, 6922, 6924, and 6926. The specific authority 
for the collection of information is 40 CFR 261.36, Exemption for 
Listed Hazardous Wastes Containing Low Concentrations of Hazardous 
Constituents.
    The Agency has prepared a full Information Collection request (ICR) 
in support of today's action. A summary of the methodology and findings 
from this document is presented in section G below.

B. Background

    In 1976, Congress passed the Resource Conservation and Recovery Act 
(RCRA) to address problems associated with annual nationwide generation 
of large quantities of municipal and industrial solid waste. This Act 
was significantly amended in 1984 by the Hazardous and Solid Waste 
Amendments (HSWA). Under RCRA, the Agency regulates non-hazardous solid 
waste through the Subtitle D program, and hazardous solid waste under 
the Subtitle C program. Subtitle C regulations differ from Subtitle D 
in two important areas. First, Subtitle C regulations are developed and 
promulgated by EPA, while Subtitle D requirements have been largely 
delegated to the states. Second, non-hazardous wastes regulated under 
Subtitle D are generally subject to standards that are considerably 
less stringent and less costly than those under Subtitle C. All wastes 
addressed under this action are currently managed under Subtitle C 
regulations.
    RCRA is divided into four programs: Underground storage, medical 
waste, nonhazardous solid waste, and hazardous solid waste. Under RCRA 
3001(a), Congress has required EPA to identify those wastes that should 
be classified as hazardous. In accordance with this provision, the 
Agency has designated wastes as hazardous in two ways: 
``characteristic,'' or ``listed.'' Hazardous waste is considered 
characteristic if it has any of the properties or characteristics that 
would present a potential hazard if managed improperly. The Agency has 
identified four characteristics which, if exhibited, lead to hazardous 
classification. These are: Ignitability, corrosivity, reactivity, and 
toxicity. Under the toxicity characteristic, specific health-based 
concentration standards have been developed for approximately forty 
(40) constituents. Wastes exhibiting any of these characteristics are 
subject to Subtitle C regulation. Hazardous wastes are identified as 
listed based on an extensive listing procedure. This procedure may 
identify a waste as hazardous under three broad categories: if it 
exhibits one of the characteristics identified above but has not been 
classified as characteristically hazardous, if it is determined to be 
acutely toxic or hazardous, or if the waste meets the statutory 
definition of a hazardous waste.
    The Agency, however, was concerned that generators and managers of 
hazardous waste might avoid regulatory requirements in two major ways: 
(1) By mixing listed hazardous waste with non-hazardous solid waste, 
and, (2) by minimal processing and treatment of hazardous waste. These 
activities could result in a waste or residual material that was no 
longer legally defined as hazardous under Subtitle C. In many cases, 
the Agency believed these materials could continue to pose unacceptable 
hazards to human health and the environment. The Agency promulgated 
mixture and derived-from rules in May of 1980, in response to these 
potential loopholes.

C. Need for Regulation

    The mixture and derived-from rules created what was perceived as 
being federal over-regulation, where listed hazardous waste continued 
to remain under Subtitle C jurisdiction regardless of constituent 
concentration or presence in the waste, either before or after 
treatment. This problem was exacerbated with the passage of HSWA in 
1984. HSWA set Land Disposal Restrictions (LDR) requiring best 
demonstrated available technology (BDAT) treatment for all listed 
hazardous wastes prior to disposal. In cases where a specific listed 
wastestream contained relatively innocuous constituents, or very low 
concentrations, BDAT treatment requirements were felt to be overly 
protective, and unnecessarily expensive.
    By requiring Subtitle C management for some low risk wastes, the 
current RCRA regulatory system may inhibit the efficient allocation of 
limited societal resources. From a social perspective, too many 
resources devoted to managing low risk wastes may reduce resource 
availability for managing higher risk wastes. Resource availability for 
general productivity investments and innovative technologies are also 
reduced. The Agency's delisting program has not provided an efficient 
solution to this problem. The delisting process has proven to be overly 
time 

[[Page 66414]]
and resource intensive for both industry and EPA.
    The Agency believes that a simpler exemption process is necessary 
to reduce the over-regulation of low risk hazardous waste while, at the 
same time, reducing the time and resource burden on industry and 
government. This revised exemption process would also reduce the burden 
on the delisting program which will continue under current regulations. 
To meet these goals, the Agency is proposing the current action that 
would establish a single set of exit levels for constituents found in 
listed hazardous waste. This action would cover wastes as-generated, 
derived-from wastes, including BDAT treatment residuals, mixtures with 
solid wastes, and environmental media that contain hazardous wastes.

D. Assessment of Potential Costs and Benefits

1. Introduction and Summary
    The U.S. Environmental Protection Agency (EPA) has prepared an 
Assessment of The Potential Costs and Benefits (Assessment) to 
accompany today's proposed rulemaking action. This action will 
establish concentration-based exemption criteria for certain hazardous 
wastes, creating a mechanism to exclude from Subtitle C regulation 
those listed industrial process wastes that the Agency believes are 
clearly not of Federal regulatory concern. Today's proposed rule 
addresses low hazard wastes, mixtures, treatment residuals, and media 
that contain hazardous wastes.
    The Agency anticipates that the proposed rule will provide cost 
savings to selected generators and managers of low hazard wastes. Under 
the preferred option, annual nationwide treatment and disposal cost 
savings for exempted wastes may be as high as $75 million. Annual cost 
savings for a single facility may be as high as $5.03 million. 
Potential cost reductions beyond treatment and disposal savings may be 
associated with waste minimization incentives, avoided treatment costs 
for wastes remaining within Subtitle C, and administrative cost 
savings.
    Exemption of eligible wastes from Subtitle C management 
requirements is projected to have negligible effects on human health 
and the environment. The proposed exemption levels are based on 
detailed analysis of numerous possible routes of exposure. These 
exemption levels are designed to be protective of both human health and 
ecological systems when exempted wastes are managed under Subtitle D, 
including state regulated waste disposal systems.
    The Agency has also evaluated other impacts of the proposed rule. 
These include: Environmental justice, unfunded mandates, regulatory 
takings, and waste minimization incentives. Environmental justice 
concerns associated with today's proposed action may be in the form of 
economic benefits and/or human health effects. Today's proposal 
implements no enforceable requirements on states. Federal unfunded 
mandates, therefore, are not relevant to today's proposed rulemaking. 
Regulatory takings under today's proposed rulemaking will not approach 
land or productive value impacts discussed in past House and Senate 
Bills presented on this issue. This rulemaking provides opportunities 
for generators to implement waste minimization procedures to gain 
additional savings.
    The complete document, Assessment of The Potential Costs and 
Benefits of The Hazardous Waste Identification Rule for Industrial 
Process Wastes, as Proposed (Assessment), is available in the docket 
established for this proposed rule. This document details the data, 
methodology, findings, regulatory issues, and analytical limitations 
associated this Assessment. The rapid evolution of this action resulted 
in continuous technical modifications throughout the development of 
this proposal. An Addendum to the Assessment document that details 
final quantity and cost savings estimates is included in the docket 
materials. Findings presented in this preamble present final estimates.
    A summary of the Assessment methodology and findings is presented 
below. The analysis conducted for this Notice of Proposed Rulemaking is 
to be considered preliminary. The Agency welcomes review and comment of 
this document and urges the submission of data in support of any 
comment or response.
2. Regulatory Options
    The Agency's Assessment, conducted in support of today's action, 
addresses the costs, benefits, and other potential impacts of the 
preferred option. The Assessment also examines various other regulatory 
options based on exit levels that are both more and less stringent. 
Findings presented in this preamble discuss the preferred option and 
one primary alternative. A full discussion of findings associated with 
various alternative regulatory options is presented in the Assessment 
and Addendum.
a. Preferred (Proposed) Option
    Under the preferred option, exit criteria are established for 
approximately 400 constituents, allowing hazardous wastes (including 
waste mixed with or derived-from listed wastes) to exit Subtitle C if 
the concentration of all constituents is less than or equal to the 
exemption criteria. The exit levels apply to all listed wastes, 
regardless of origin.
    Exit levels for most constituents are based on risks posed to human 
health and the environment. The Agency's goal is to ensure, through 
Federal or State management requirements, that humans are not exposed 
to carcinogens in concentrations that will increase the statistical 
risk of cancer by more that one-in-one-million (1 x 10-6). For 
non-carcinogens, the Agency's goal is to ensure that humans are not 
exposed to concentrations where the hazard quotient exceeds one (1). 
The Agency feels that, above this level, selected populations may 
experience carcinogenic effects at a 10-6 risk level and non-
carcinogenic effects at a hazard quotient greater than one (1).
    To determine the concentrations at which exempt wastes would not 
pose human health risks in excess of these target levels, EPA conducted 
a ``Multipathway'' Analysis that included ecological exposure pathways. 
In addition, EPA considered the effects of direct exposure to 
contaminants in groundwater. The analyses consider several types of 
waste management units. For non-wastewaters these unit types include 
landfills, land application units, waste piles, and ash monofills. For 
wastewaters management units included tanks and surface impoundments.
    The concentrations from all other pathways were compared to the 
groundwater concentrations in determining the exit level. The more 
stringent of the multipathway or groundwater numbers was chosen as the 
exit level. Exit levels for some constituents are based on surrogates, 
or Exemption Quantitation Criteria (EQCs). MCLs were not used in the 
development of exit levels analyzed for this option. The Agency 
believes that levels established under this process will ensure 
protection of human health and the environment. These exit levels are 
presented in the regulatory language for this proposed rulemaking.
b. Other Options
    In developing the preferred option, the Agency compared the 
proposed rule to several alternative regulatory options. These are 
discussed in the full 

[[Page 66415]]
document, Assessment of The Potential Costs and Benefits of The 
Hazardous Waste Identification Rule for Industrial Process Wastes, as 
Proposed. Additional options are discussed in the supporting Addendum 
to the Assessment document. These options consider alternative waste 
management requirements, target risk levels, dilution and attenuation 
factors (DAFs), and exposure pathways. This Preamble discusses one 
primary alternative to the preferred option. This alternative is the 
same as the preferred option but drops land application units from 
consideration as a management source. Exempt nonwastewater wastestreams 
could not be land applied. There would be no change for wastewaters.
3. Implementation Requirements
    Implementation requirements include the steps that generators (or 
waste managers) must take to achieve exemption of their wastes, 
regardless of the exit levels selected. These requirements include 
waste sampling and analysis, and related recordkeeping and reporting. 
Under the proposed rule, the facility must first perform a 
comprehensive analysis of the waste, testing for all constituents 
identified in appendix X to 40 CFR part 261. Reduced initial testing 
may be possible only if a facility is able to document that such 
constituents are not present in the waste. The generator must then 
prepare a notification/certification package and submit it to the EPA 
Regional Administrator or authorized state agency. The generator must 
repeat a comprehensive analysis periodically according to the schedule 
established in the proposed rule, along with more frequent tailored 
scans that focus on the constituents of concern. Related documentation 
must be maintained on-site and be available for review.
    The Agency has estimated annual sampling, analysis, recordkeeping, 
and reporting costs (collectively referred to as ``implementation 
costs'') that may be required under this rule. These estimates range 
from approximately $21,000 for a less complex, solvent wastestream with 
testing every 12 months, to $169,000 for a complex high quantity F039 
wastestream with testing every three months.
4. Analysis and Findings
    Under the proposed rule, listed wastes from industrial processes 
may be eligible for exemption from Subtitle C hazardous waste 
requirements if they contain low concentrations of contaminants. This 
exemption may allow generators and waste managers to avoid some or all 
costs associated with Subtitle C requirements. The most significant 
cost savings relate to waste treatment and disposal; this rule will 
allow generators to avoid the costs of treatment required for 
compliance with the Land Disposal Restrictions as well as the costs of 
disposing wastes in highly protective Subtitle C facilities.
    In addition to assessing these cost savings, the Assessment 
addresses a number of other potential effects of the regulations. It 
analyzes the relative effects of the regulatory options on human health 
and the environment and considers issues related to ensuring 
environmental justice, eliminating federal mandates, encouraging waste 
minimization, and providing flexibility for small businesses.
a. Eligible Waste
    The universe of annual listed waste generation, both wastewaters 
and nonwastewaters, potentially affected by today's proposed rulemaking 
is estimated to total 303.6 million tons. The universe of potentially 
affected wastes includes approximately 25,300 wastestreams from 10,700 
facilities. Wastewaters account for the vast majority of total waste 
quantity (99 percent).
    To determine whether these wastes are likely to be eligible for 
exemption, EPA developed the Process Waste Model. This model uses data 
on the characteristics of individual listed waste-streams first 
collected in 1986 for EPA's National Survey of Hazardous Waste 
Generators, which has since been updated, refined, and in some cases, 
corrected. The model first compares the reported concentrations of 
constituents in each wastestream to the proposed rule exit levels to 
determine whether the waste is likely to be eligible for exemption 
without further treatment. If the waste is not eligible as-reported, 
the model then considers whether it may be eligible after treatment. In 
this comparison, the concentration standards established under EPA's 
Land Disposal Restrictions (which are based on the use of the best 
demonstrated and available technology) are used as a proxy for the 
lowest concentrations achievable by treatment. If the waste is not 
eligible for exemption as-reported or after treatment, EPA assesses 
whether waste minimization or pollution prevention methods could be 
used to cost-effectively achieve the exit levels. This model does not 
address contaminated media.
    The analysis indicates that:
     Under the preferred option, total nonwastewater quantity 
exempted, including BDAT treatment residuals and sludge from 
wastewater, is estimated at 0.40 million tons. Total wastewater 
(liquid) quantity exempted is approximately 64 million tons.
     Under the primary alternative option (no land 
application), approximately 65 million tons of wastewaters, and 0.60 
million tons of nonwastewaters, including BDAT treatment residuals and 
sludge from wastewaters, may be eligible for exemption.
b. Cost Savings
    The proposed rule will allow waste generators and managers to avoid 
costs associated with Subtitle C requirements. Specifically, this 
exemption will allow them to avoid treatment costs and/or costs of 
disposing wastes in Subtitle C facilities. Wastes which meet exit 
levels at the point of generation may accrue treatment cost savings 
because the wastes will not require any treatment that would have been 
needed to comply with the Subtitle C Land Disposal Restrictions prior 
to disposal. All exempt wastes are likely to accrue disposal cost 
savings because the costs of disposing wastes in non-Subtitle C 
facilities are generally lower than the cost of more protective 
Subtitle C facilities.
    The analysis indicates that:
     Under the preferred option, the high-end estimate of 
annual treatment and disposal cost savings is approximately $75 
million.

--A large portion of these savings are attributable to avoided 
treatment costs.

     Under the primary alternative, the high-end estimate of 
cost savings is $99 million.
    The above estimates for quantities exempted and cost savings assume 
zero implementation costs. The incorporation of implementation costs 
into the analytical model will have a significant impact on facilities 
and wastestreams affected, while having only a marginal impact on total 
quantities exempted.
c. Affected Wastestreams and Facilities
    Under the preferred option (unconditional exemption), as high as 41 
percent (10,300) of the potentially affected wastestreams may be 
eligible for exemption. These eligible wastestreams are generated by 56 
percent (6000) of the facilities producing listed waste. Total 
wastestreams and facilities potentially eligible for exemption under 
the primary alternative option (no land application) are estimated at 
12,200 (48 percent), and 7,000 (65 percent), respectively. 

[[Page 66416]]

    The majority of the wastestreams eligible for exemption under the 
preferred option are very small in quantity. The median annual 
generation size of an eligible wastewater wastestream is 20 tons. The 
median for eligible nonwastewaters is 2.0 tons. For small wastestreams, 
the costs accrued due to the exemption are likely to be counterbalanced 
by the costs associated with gaining the exemption.
    While a relatively large number of wastestreams and facilities meet 
the eligibility criteria for exemption, many may not gain exemption 
because the costs of exemption may outweigh the estimated cost savings 
from exemption. For example, if implementation costs average $35,000 
annually per wastestream, the estimate of facilities generating an 
exempted wastestream may be overstated by as much as 90 percent. 
However, small generators may choose to aggregate their wastes to avoid 
this problem.
d. Relative Impacts on Human Health and the Environment
    Today's proposed rule will allow low concentration hazardous wastes 
to exit RCRA Subtitle C regulation and be disposed of in Subtitle D 
nonhazardous waste units. The Agency believes that today's proposed 
rule will have little effect on human health for the following reasons:
     The acceptable daily exposure levels used to set the exit 
levels are based on maximum risk levels for carcinogens of 10-6 
and on acceptable daily doses for non-carcinogens at which no adverse 
effects are likely to occur.
     The waste management units modeled in the Multipathway 
Analysis provide high potential release rates for the various groups of 
constituents being considered in the analysis based on their physical 
and chemical properties.
     The pathways included in the Multipathway Analysis are 
generally considered to be the most critical.
     The Multipathway Analysis includes populations that are 
likely to be exposed more than the average adult due to proximity to a 
contaminant source, behavior patterns, activities, and body size.
     High-end values were used for selected parameters in the 
Multipathway Analysis to calculate acceptable waste concentrations.
     Exit levels represent acceptable constituent concentration 
levels for Subtitle D waste management based on all of the potential 
combinations of management units, and receptors in the Multipathway 
Analysis.
     Exit levels for several constituents are below the 
acceptable waste concentrations for human health due to the inclusion 
of ecological receptors.
    Ecological risks were also evaluated for selected key constituents. 
The inclusion of such risk in solid waste regulation at a national 
level is an important step, and is preferable to establishing exit 
criteria based only on human health risks.
5. Other Regulatory Issues
a. Environmental Justice
    Economic benefits may occur to selected communities as affected 
local facilities reinvest cost savings derived from reduced treatment 
and/or disposal costs. Human health effects are expected to be 
negligible due to the stringency of the exit levels. Included in these 
exit levels are pathways of particular concern for selected low income 
populations such as subsistence fishing and farming.
b. Other Issues
    Today's proposal is expected to have no impact in the area of 
Unfunded Federal Mandates or Regulatory Takings. Waste minimization 
procedures are likely to be stimulated under this proposal.
6. Implications and Conclusions
    The analysis indicates that approximately 11 percent of the 
quantity of all nonwastewaters containing listed codes, and 21 percent 
of all such wastewaters may be eligible for exemption under the 
proposed rule. This exempt quantity is dominated by a small number of 
very large wastestreams, and includes a large number of very small 
wastestreams. For some small wastestreams, exemption may not be cost 
effective unless generators aggregate their wastes or otherwise work 
cooperatively to minimize the costs of gaining the exemptions.
    Today's proposal could also provide incentives for industry to 
implement process changes and increased recycling in an effort to gain 
additional savings. Preliminary estimates indicate that savings from 
these activities, when combined with treatment and disposal savings 
from the preferred option, are likely to result in total annual cost 
savings greater than $100 million. However, limitations of our analysis 
suggest that the cost savings estimates from such activities are highly 
uncertain. Additional savings related to administrative requirements 
and reduced treatment for hazardous wastes may also accrue. These 
potential additional cost savings are discussed in greater detail in 
the Assessment document.
    The Agency believes that today's proposal will result in a net 
benefit to society. Wastes gaining exemption under the preferred option 
will not pose unacceptable incremental risks to human health and the 
environment because the exit levels are based on extensive analysis of 
possible human and ecological risks associated with exempt wastes.
    EPA's analysis of the impact of today's proposal on industry groups 
indicates that a limited number of industries are likely to benefit 
from exemption. Under the preferred option (unconditional exemption), 
three industries account for 51 percent of eligible nonwastewater and 
wastewater sludge quantity and 53 percent of total treatment and 
disposal cost savings. These industries are: Chemicals and allied 
products (SIC 28); fabricated metals (SIC 34); and primary metals (SIC 
33).
    The Agency also compared benefits gained from exemption to key 
industry data such as national pollution abatement expenditures and 
considered facility level impacts of the proposal. To evaluate the 
relative magnitude of cost savings that would accrue under the proposed 
rule, EPA compared cost savings estimates to total pollution abatement 
expenditures and the total value of industry shipments. Total treatment 
and disposal cost savings under the preferred option account for 
approximately 3.5 percent of annual operating costs for hazardous waste 
pollution abatement activities, and less than 0.002 percent of the 
total value of industry shipments. The facility-level impacts of the 
proposal vary greatly.

E. Regulatory Flexibility Analysis.

    The Regulatory Flexibility Act requires analysis of the impact of 
regulations on small entities. Because today's proposal is 
deregulatory, it is not expected to have adverse impacts on small 
businesses. In general, generators of large quantity wastestreams 
posing low hazards will benefit substantially from the regulations. The 
impacts on small quantity generators is less certain and depends on the 
degree to which they aggregate their wastes and work cooperatively to 
cost-effectively gain exemption.

F. Environmental Justice

    It is the Agency's policy that environmental justice be considered 
as an integral part in the development of all policies, guidance and 
regulations. Further, Executive Order 12898, ``Federal Actions to 
Address 

[[Page 66417]]
Environmental Justice in Minority Populations and Low-Income 
Populations'', directs each Federal Agency to ``make achieving 
environmental justice part of its mission by identifying and 
addressing, as appropriate, disproportionately high and adverse human 
health and environmental effects of its programs, policies, and 
activities on minority populations and low-income populations * * * ''
    The Executive Order requires that where environmental justice 
concerns or the potential for concerns are identified, appropriate 
analysis of the issue(s) be evaluated. To the extent practicable, the 
ecological, human health (taking into account subsistence patterns and 
sensitive populations) and socio-economic impacts of the proposed 
decision-document in minority and low-income communities should also be 
evaluated. Examples include how a policy on future land use would 
impact minority or low-income communities versus non-minority, affluent 
communities, or how subsistence farming or fishing patterns relate to 
risk-assessment policies.
    For the purposes of today's proposed rulemaking, the Agency has 
taken an approach for proposal consistent with Executive Order 12898. 
As currently drafted, the multipathway analysis which was used to 
develop the exit levels takes into account subsistence farmers and 
subsistence fishers; however, subsistence fishers were evaluated using 
a recreational fisher database (one does not exist for subsistence 
fishers). Sensitive populations are accounted for in the RfDs, RfCs, 
and slope factors and ecological receptors were also evaluated.

G. Paperwork Reduction Act

    As stated earlier, the level of implementation costs (i.e. 
sampling, analysis, recordkeeping, and reporting) will have a 
significant impact on the number of wastestreams and facilities 
affected by this proposal. Assuming annual implementation costs of 
$35,000 per wastestream, as many as 269 facilities, generating up to 
285 different wastestreams may seek exemptions, and therefore be 
affected by the recordkeeping and reporting requirements. The actual 
number of facilities and wastestreams affected will depend upon the 
level of implementation costs. The higher the implementation cost to 
the facility, the fewer the number of facilities expected to 
participate in the HWIR program.
    The estimated hour burden ranges from 382 hours to 573 hours per 
wastestream in the first year, and from 31 hours to 146 hours per 
wastestream in years two and three. The variation in burden estimates 
results from different assumptions in (1) the complexity of the waste 
(and therefore of the test methods required), and (2) the frequency of 
reporting. The estimated total hour burden over the first three years 
ranges from 206,900 to 293,465 hours, averaging 68,967 to 97,821 hours 
per year.
    The estimated total start-up cost of recordkeeping and reporting in 
the first year ranges from $55,000 to $235,000 per wastestream. The 
annual cost in the second and third years is estimated to be $9,000 to 
$209,000 per wastestream (of which $8,000 to $203,000 is the cost of 
shipping samples to a laboratory and paying to have them tested). In 
years four and five the high-end cost drops to $53,000. The estimated 
annual recordkeeping and reporting cost per wastestream, annualized at 
seven percent over five years, is $21,000 to $170,000. The total 
recordkeeping and reporting cost burden over the first three years is 
$28,000,000 to $32,000,000.
    Burden means the total time, effort, or financial resources 
expended by persons to generate, maintain, retain, or disclose or 
provide information to or for a Federal agency. This includes the time 
needed to review instructions; develop, acquire, install, and utilize 
technology and systems for the purposes of collecting, validating, and 
verifying information, processing and maintaining information, and 
disclosing and providing information; adjust the existing ways to 
comply with any previously applicable instructions and requirements; 
train personnel to be able to respond to a collection of information; 
search data sources; complete and review the collection of information; 
and transmit or otherwise disclose the information.
    An Agency may not conduct or sponsor, and a person is not required 
to respond to a collection of information unless it displays a 
currently valid OMB control number. The OMB control numbers for EPA's 
regulations are listed in 40 CFR part 9 and 48 CFR chapter 15.
    Comments are requested on the Agency's need for this information, 
the accuracy of the provided burden estimates, and any suggested 
methods for minimizing respondent burden, including through the use of 
automated collection techniques. Send comments on the ICR to the 
Director, OPPE Regulatory Information Division; U.S. Environmental 
Protection Agency (2137); 401 M St., SW.; Washington, DC 20460; and to 
the Office of Information and Regulatory Affairs, Office of Management 
and Budget, 725 17th St., NW., Washington, DC 20503, marked 
``Attention: Desk Officer for EPA.'' Include the ICR number in any 
correspondence. Since OMB is required to make a decision concerning the 
ICR between 30 and 60 days after December 21, 1995, a comment to OMB is 
best assured of having its full effect if OMB receives it by January 
22, 1996. The final rule will respond to any OMB or public comments on 
the information collection requirements contained in this proposal.

List of Subjects in 40 CFR 261 and 268

    Identification and listing of hazardous waste. Land disposal 
restrictions.

    Dated: November 13, 1995.
Carol Browner,
Administrator.

XV. References

U.S. Environmental Protection Agency, Environmental Monitoring 
Systems Laboratory; ``Performance Testing of Method 1312--QA Support 
for RCRA Testing.'' EPA/600/4-89/022, June 1989.
Research Triangle Institute; ``Interlaboratory Comparison of Methods 
1310, 1311, and 1312 for Lead in Soil''. U.S. EPA Contract 68-01-
7075, November 1988.
U.S. Environmental Protection Agency, Office of Solid Waste and 
Emergency Response; OSWER Directive No. 9285.7; ``Human Health 
Evaluation Manual, Part B: Development of Risk-based Preliminary 
Remediation Goals;'' from Henry Longest II, Director, Office of 
Emergency and Remedial Response; and Bruce Diamond, Director, Office 
of Waste Programs Enforcement; to Regional Waste Management Division 
Directors; December 13, 1991.
U.S. Environmental Protection Agency, Office of Solid Waste and 
Emergency Response; OSWER Directive No. 9850.4; ``Interim Final 
Guidance for Soil Ingestion Rates;'' from J. Winston Porter, OSWER 
Assistant Administrator; to Regional Administrators (I-X); January 
27, 1989.
U.S. Environmental Protection Agency, Office of Research and 
Development, Office of Health and Environmental Assessment; 
``Exposure Factors Handbook;'' EPA/600/8-89/043, March 1990.
U.S. Environmental Protection Agency, Office of Solid Waste: EPA's 
Composite Model for Leachate Migration with Transformation Products 
(EPACMTP), Background Document, 1995a.
U.S. Environmental Protection Agency, Office of Solid Waste: EPA's 
Composite Model for Leachate Migration with Transformation Products 
(EPACMTP), User's Guide, 1995b.
U.S. Environmental Protection Agency, Office of Solid Waste: Finite 
Source Methodology for Non-Degrading and Degrading Chemicals with 
Transformation Products, 1995c.
U.S. Environmental Protection Agency, Office of Solid Waste: 
Background 

[[Page 66418]]
Document for EPACMTP: Fate and Transport Modeling of Metals, 1995d.
U.S. Environmental Protection Agency, Office of Research 
Development. Finite Source Methodology for Wastes Containing Metals, 
1992.
U.S. Environmental Protection Agency, Office of Research Development 
MINTEQA2/PRODEFA2, A Geochemical Assessment Model for Environmental 
Systems: Version 3.0 User's Manual. EPA/600/3-91/021, March 1991.
U.S. Environmental Protection Agency, Office of Research 
Development. Environmental Fate Constants for Chemicals Under 
Consideration for EPA's Hazardous Waste Identification Projects, 
compiled by Heinz Kollig, 1993.

Appendix A

                                       Table A-1.--Human Exposure Pathways                                      
----------------------------------------------------------------------------------------------------------------
       Exposure medium              Route of exposure        Type of fate and transport         Pathway a       
----------------------------------------------------------------------------------------------------------------
Groundwater.................  Ingestion...................  Groundwater................  1                      
                                                                                         WMU           
                                                                                          groundwater  
                                                                                          humans                
                                                                                         Ingestion of           
                                                                                          contaminated          
                                                                                          groundwater as a      
                                                                                          drinking water source.
Air.........................  Inhalation..................  Direct air.................  2a (on site or off     
                                                                                          site)                 
                                                                                         WMU  air  humans         
                                                                                         Inhalation of volatiles
Air.........................  Inhalation..................  Direct air.................  2b (on site or off     
                                                                                          site)                 
                                                                                         WMU  air  humans         
                                                                                         Inhalation of suspended
                                                                                          particulates          
Soil........................  Ingestion...................  Direct soil................  3 (on site)            
                                                                                         WMU  humans   
                                                                                         Ingestion of           
                                                                                          contaminated soil     
Soil........................  Ingestion...................  Overland...................  3 (off site)           
                                                                                         WMU  overland 
                                                                                           humans      
                                                                                         Ingestion of           
                                                                                          contaminated soil     
Soil........................  Ingestion...................  Air deposition.............  4                      
                                                                                         WMU  air  deposition to  
                                                                                          soil  humans 
                                                                                         Ingestion of           
                                                                                          contaminated soil     
Soil........................  Dermal......................  Direct soil................  5 (on site)            
                                                                                         WMU  humans   
                                                                                         Dermal contact with    
                                                                                          contaminated soil     
Soil........................  Dermal......................  Overland...................  5 (off site)           
                                                                                         WMU  overland 
                                                                                           humans      
                                                                                         Dermal contact with    
                                                                                          contaminated soil     
Soil........................  Dermal......................  Air deposition.............  6                      
                                                                                         WMU  air  deposition to  
                                                                                          surface soil 
                                                                                          humans                
                                                                                         Dermal contact with    
                                                                                          contaminated soil     
Plant (veg/root)............  Ingestion...................  Air deposition.............  8                      
                                                                                         WMU  air  deposition to  
                                                                                          soil/gard crops  garen crops  humans         
                                                                                         Consumption of         
                                                                                          contaminated crops    
                                                                                          grown in home gardens 
Plant (veg).................  Ingestion...................  Air diffusion..............  8a                     
                                                                                         WMU  air  garden crops  humans         
                                                                                         Consumption of         
                                                                                          contaminated crops    
                                                                                          grown in home gardens 
Plant (veg/root)............  Ingestion...................  Direct soil................  9 (on site)            
                                                                                         WMU  garden   
                                                                                          crops  humans
                                                                                         Consumption of         
                                                                                          contaminated crops    
                                                                                          grown in home gardens 
Plant (veg/root)............  Ingestion...................  Overland...................  9 (off site)           
                                                                                         WMU  overland 
                                                                                           garden crops
                                                                                           humans      
                                                                                         Consumption of         
                                                                                          contaminated crops    
                                                                                          grown in home gardens 
Animal (beef/milk)..........  Ingestion...................  Air deposition.............  10                     
                                                                                         WMU  air  deposition to  
                                                                                          soil/feed crops  cattle  humans         
                                                                                         Consumption of animal  
                                                                                          products with elevated
                                                                                          levels of toxicant    
                                                                                          caused by eating      
                                                                                          contaminated feed     
                                                                                          crops and soil        
Animal (beef/milk)..........  Ingestion...................  Air diffusion..............  10a                    
                                                                                         WMU  air  feed crops  cattle  humans         
                                                                                         Consumption of animal  
                                                                                          products with elevated
                                                                                          levels of toxicant    
                                                                                          caused by eating      
                                                                                          contaminated feed     
                                                                                          crops                 
Animal (beef/milk)..........  Ingestion...................  Direct soil................  11 (on site)           
                                                                                         WMU  feed     
                                                                                          crops  cattle
                                                                                           humans      
                                                                                         Consumption of animal  
                                                                                          products with elevated
                                                                                          levels of toxicant    
                                                                                          caused by eating      
                                                                                          contaminated feed     
                                                                                          crops and soil        
Animal (bedf/milk)..........  Ingestion...................  Overland...................  11 (off site)          
                                                                                         WMU  overland 
                                                                                           feed crops/ 
                                                                                          soil  cattle 
                                                                                           humans      
                                                                                         Consumption of animal  
                                                                                          products with elevated
                                                                                          levels of toxicant    
                                                                                          caused by eating      
                                                                                          contaminated feed     
                                                                                          crops and soil        
Groundwater.................  Dermal (bathing)............  Groundwater................  14                     
                                                                                         WMU           
                                                                                          groundwater  
                                                                                          humans                
                                                                                         Ingestion of           
                                                                                          contaminated surface  
                                                                                          water as a drinking   
                                                                                          water source          
Surface water...............  Ingestion...................  Air diffusion..............  17                     
                                                                                         WMU           
                                                                                          groundwater  
                                                                                          humans                
                                                                                         Dermal bathing contact 
                                                                                          with contaminated     
                                                                                          groundwater           

[[Page 66419]]
                                                                                                                
Surface water...............  Ingestion...................  Overland...................  19                     
                                                                                         WMU  overland 
                                                                                          flow  surface
                                                                                          water  humans
                                                                                         Ingestion of           
                                                                                          contaminated surface  
                                                                                          water as a drinking   
                                                                                          water source          
Surface water...............  Ingestion...................  Air deposition.............  20                     
                                                                                         WMU  air  deposition to  
                                                                                          soil         
                                                                                          overland flow  surface water  
                                                                                           humans      
                                                                                         Ingestion of           
                                                                                          contaminated surface  
                                                                                          water as a drinking   
                                                                                          water source          
Fish........................  Ingestion...................  Air diffusion..............  21                     
                                                                                         WMU  air  surface water  
                                                                                           fish  humans         
                                                                                         Consumption f fish     
                                                                                          contaminated by       
                                                                                          toxicants in surface  
                                                                                          water                 
Fish........................  Ingestion...................  Overland...................  23                     
                                                                                         WMU  overland 
                                                                                           surface     
                                                                                          water  fish  
                                                                                           humans      
                                                                                         Consumption f fish     
                                                                                          contaminated by       
                                                                                          toxicants in surface  
                                                                                          water                 
Fish........................  Ingestion...................  Air deposition.............  24                     
                                                                                         WMU  air  deposition to  
                                                                                          surface soil 
                                                                                          overland flow  surface water  
                                                                                           fish  humans         
                                                                                         Consumption f fish     
                                                                                          contaminated by       
                                                                                          toxicants in surface  
                                                                                          water                 
Animal (beef/milk)..........  Ingestion...................  Air diffusion..............  33                     
                                                                                         WMU  air  suface water  cattle  humans         
                                                                                         Consumption of animal  
                                                                                          products with elevated
                                                                                          levels of toxicant    
                                                                                          caused by drinking    
                                                                                          contaminated surface  
                                                                                          water                 
Animal (beef/milk)..........  Ingestion...................  Overland...................  35                     
                                                                                         WMU  overland 
                                                                                          flwo  surface
                                                                                          water  cattle
                                                                                           humans      
                                                                                         Consumption of animal  
                                                                                          products with elevated
                                                                                          levels of toxicant    
                                                                                          caused by drinking    
                                                                                          contaminated surface  
                                                                                          water                 
Animal (beef/milk)..........  Ingestion...................  Air deposition.............  36                     
                                                                                         WMU  air  deposition to  
                                                                                          soil         
                                                                                          overland flow  surface water  
                                                                                           cattle  humans         
                                                                                         Consumption of animal  
                                                                                          products with elevated
                                                                                          levels of toxicant    
                                                                                          caused by drinking    
                                                                                          contaminated surface  
                                                                                          water                 
Surface water...............  Dermal (bathing)............  Air diffusion..............  37                     
                                                                                         WMU  air  surface water  
                                                                                           humans      
                                                                                         Dermal bathing contact 
                                                                                          with contaminated     
                                                                                          surface water         
Surface water...............  Dermal (bathing)............  Air deposition.............  38                     
                                                                                         WMU  air      
                                                                                          deposition to soil  overland flow  
                                                                                           surface     
                                                                                          water  humans
                                                                                         Dermal bathing contact 
                                                                                          with contaminated     
                                                                                          surface water         
Surface water...............  Dermal (bathing)............  Overland...................  42                     
                                                                                         WMU  overland 
                                                                                          flow  surface
                                                                                          water  humans
                                                                                         Dermal bathing contact 
                                                                                          with contaminated     
                                                                                          surface water         
----------------------------------------------------------------------------------------------------------------
Overland = Soil erosion; Overland flow = Both runoff and sold erosion; or, for surface impoundments, a spill    
  directly to surface water. Veg = Aboveground fruits and vegetables. Root = Belowground (or root) vegetables.  
                                                                                                                
a Some pathway numbers are missing, reflecting pathways that have been eliminated from the analysis or combined 
  with other pathways.                                                                                          



                                                        Table A-2.--Ecological Exposure Pathways                                                        
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                  Exposure medium                 Route of exposure            Type of fate and transport             Pathways a        
--------------------------------------------------------------------------------------------------------------------------------------------------------
Terr I..................  Soil...........................  Ingestion......................  Direct soil....................  3 (on site)                
                                                                                                                             WMU  mammals,     
                                                                                                                              birds, soil fauna         
                                                                                                                             Ingestion of contaminated  
                                                                                                                              soil                      
                          Soil...........................  Direct contact.................  Direct soil....................  5 (on site)                
                                                                                                                             WMU  plants, soil 
                                                                                                                              fauna                     
                                                                                                                             Direct contact with        
                                                                                                                              contaminated soil         
                          Plant..........................  Ingestion......................  Direct soil....................  9 (on site)                
                                                                                                                             WMU  vegetation  mammals, birds     
                                                                                                                             Consumption of contaminated
                                                                                                                              vegetation (e.g., forage  
                                                                                                                              grasses)                  
                          Soil fauna.....................  Ingestion......................  Direct soil....................  11a (on site)              
                                                                                                                             WMU  soil fauna  mammals, birds     
                                                                                                                             Consumption of soil fauna  
                                                                                                                              (e.g., earthworms,        
                                                                                                                              insects) with elevated    
                                                                                                                              levels of toxicant        
                          Animals........................  Ingestion......................  Direct soil....................  11b (on site)              
                                                                                                                             WMU  soil fauna/  
                                                                                                                              vegetation       
                                                                                                                              animals          
                                                                                                                              predatory mammals, birds  
                                                                                                                             Consumption of animals with
                                                                                                                              elevated levels of        
                                                                                                                              toxicant                  
Terr II.................  Soil...........................  Ingestion......................  Overland.......................  3 (off site)               
                                                                                                                             WMU  overland  mammals, birds,    
                                                                                                                              soil fauna                
                                                                                                                             Ingestion of contaminated  
                                                                                                                              soil                      

[[Page 66420]]
                                                                                                                                                        
                          Soil...........................  Direct contact.................  Overland.......................  5 (off site)               
                                                                                                                             WMU  overland  plants, soil fauna 
                                                                                                                             Direct contact with        
                                                                                                                              contaminated soil         
                          Plant..........................  Ingestion......................  Overland.......................  9 (off site)               
                                                                                                                             WMU  overland  vegetation  mammals, birds     
                                                                                                                             Consumption of contaminated
                                                                                                                              vegetation (e.g., forage  
                                                                                                                              grasses)                  
                          Soil fauna.....................  Ingestion......................  Overland.......................  11c (off site)             
                                                                                                                             WMU  overland  soil fauna  mammals, birds     
                                                                                                                             Consumption of soil fauna  
                                                                                                                              (e.g., earthworms,        
                                                                                                                              insects) with elevated    
                                                                                                                              levels of toxicant        
                          Animals........................  Ingestion......................  Overland.......................  11d (off site)             
                                                                                                                             WMU  soil fauna/  
                                                                                                                              vegetation       
                                                                                                                              animals          
                                                                                                                              predatory mammals, birds  
                                                                                                                             Consumption of animals with
                                                                                                                              elevated levels of        
                                                                                                                              toxicant                  
Terr III................  Soil...........................  Ingestion......................  Air deposition.................  4                          
                                                                                                                             WMU  air 
                                                                                                                              deposition to soil  mammals, birds,    
                                                                                                                              soil fauna                
                                                                                                                             Ingestion of contaminated  
                                                                                                                              soil                      
                          Soil...........................  Direct contact.................  Air deposition.................  6                          
                                                                                                                             WMU  air 
                                                                                                                              deposition to surface soil
                                                                                                                               plants, soil    
                                                                                                                              fauna                     
                                                                                                                             Direct contact with        
                                                                                                                              contaminated soil         
Terr IV.................  Plant..........................  Ingestion......................  Air deposition.................  8                          
                                                                                                                             WMU  air 
                                                                                                                              deposition to soil  vegetation  mammals, birds     
                                                                                                                             Consumption of contaminated
                                                                                                                              vegetation (e.g., forage  
                                                                                                                              grasses)                  
Terr V..................  Plant..........................  Ingestion......................  Air diffusion..................  8                          
                                                                                                                             WMU  air 
                                                                                                                              vegetation       
                                                                                                                              mammals, birds            
                                                                                                                             Consumption of contaminated
                                                                                                                              vegetation (e.g., forage  
                                                                                                                              grasses)                  
Aq I....................  Surface water..................  Ingestion......................  Air diffusion..................  17                         
                                                                                                                             WMU  air 
                                                                                                                              surface water    
                                                                                                                              mammals, birds            
                                                                                                                             Ingestion of contaminated  
                                                                                                                              surface water as a        
                                                                                                                              drinking water source     
                          Fish...........................  Ingestion......................  Air diffusion..................  21                         
                                                                                                                             WMU  air 
                                                                                                                              surface water    
                                                                                                                              fish  mammals,   
                                                                                                                              birds, fish               
                                                                                                                             Consumption of fish        
                                                                                                                              contaminated by toxicants 
                                                                                                                              in surface water          
                          Surface water..................  Direct contact.................  Air diffusion..................  37                         
                                                                                                                             WMU  air 
                                                                                                                              surface water    
                                                                                                                              fish, daphnids, benthos   
                                                                                                                             Direct contact with        
                                                                                                                              contaminated surface      
                                                                                                                              water, sediments          
Aq II...................  Surface water..................  Ingestion......................  Air deposition.................  37                         
                                                                                                                             WMU  air 
                                                                                                                              deposition to soil  overland flow  surface water  mammals, birds     
                                                                                                                             Ingestion of contaminated  
                                                                                                                              surface water as a        
                                                                                                                              drinking water source     
                          Fish...........................  Ingestion......................  Air deposition.................  24                         
                                                                                                                             WMU  air 
                                                                                                                              deposition to surface soil
                                                                                                                               overland flow  surface water  fish      
                                                                                                                              mammals, birds, fish      
                                                                                                                             Consumption of fish        
                                                                                                                              contaminated by toxicants 
                                                                                                                              in surface water          
                          Surface water..................  Direct contact.................  Air deposition.................  38                         
                                                                                                                             WMU  air 
                                                                                                                              deposition to soil  overland flow  surface water  fish, daphnids,    
                                                                                                                              benthos                   
                                                                                                                             Direct contact with        
                                                                                                                              contaminated surface      
                                                                                                                              water, sediments          
Aq III..................  Surface water..................  Ingestion......................  Overland.......................  19                         
                                                                                                                             WMU  overland flow
                                                                                                                               surface water  mammals, birds     
                                                                                                                             Ingestion of contaminated  
                                                                                                                              surface water as a        
                                                                                                                              drinking water source     
                          Fish...........................  Ingestion......................  Overland.......................  23                         
                                                                                                                             WMU  overland flow
                                                                                                                               surface water  fish      
                                                                                                                              mammals, birds, fish      
                                                                                                                             Consumption of fish        
                                                                                                                              contaminated by toxicants 
                                                                                                                              in surface water          
                          Surface water..................  Direct contact.................  Overland.......................  42                         
                                                                                                                             WMU  overland flow
                                                                                                                               surface water  fish, daphnids,    
                                                                                                                              benthos                   
                                                                                                                             Direct contact with        
                                                                                                                              contaminated surface      
                                                                                                                              water, sediments          
--------------------------------------------------------------------------------------------------------------------------------------------------------
Overland=Soil erosion. Overland flow=Both runoff and soil erosion; or, for surface impoundments, a spill directly to surface water.                     

[[Page 66421]]
                                                                                                                                                        
a Some pathway numbers are missing, reflecting pathways that have been eliminated from the analysis.                                                    



                          Table A-3.--Summary of Human Receptors for Exposures Pathways                         
----------------------------------------------------------------------------------------------------------------
                                                                   Receptor                                     
                             -----------------------------------------------------------------------------------
           Pathway                                       Subs.       Home        Subs.       Fish               
                                 Adult       Child      farmer     gardener     fisher     consumer     Worker  
----------------------------------------------------------------------------------------------------------------
1: Groundwater-ingestion....                                                                           
                                      a   ..........  ..........  ..........  ..........  ..........  ..........
2a: Direct air-inhalation of                                                                                    
 violates (on site).........                                                                           
                                      a   ..........  ..........  ..........  ..........  ..........   
2a: Direct air-inhalation of                                                                                    
 volatiles (off site).......     ..........  ..........  ..........  ..........  ..........  ..........
2b: Direct air-inhalation of                                                                                    
 particles (on site)........                                                                           
                                      a   ..........  ..........  ..........  ..........  ..........   
2b: Direct air-inhalation of                                                                                    
 particles (off site).......     ..........  ..........  ..........  ..........  ..........  ..........
3: Direct soil-soil                                                                                             
 ingestion (on site)........                                                                           
                                      a                                                                
                                                  a   ..........  ..........  ..........  ..........  ..........
3: Overland-soil ingestion                                                                                      
 (off site).................        ..........  ..........  ..........  ..........  ..........
4: Air deposition-soil                                                                                          
 ingestion..................        ..........  ..........  ..........  ..........  ..........
5: Direct soil-dermal (soil)                                                                                    
 (on site)..................                                                                           
                                      a                                                                
                                                  a   ..........  ..........  ..........  ..........   
5: Direct Soil-dermal (off                                                                                      
 site)......................        ..........  ..........  ..........  ..........  ..........
6: Air deposition-dermal                                                                                        
 (soil).....................        ..........  ..........  ..........  ..........  ..........
8: Air deposition-veg/root                                                                                      
 ingestion..................  ..........  ..........           ..........  ..........
8a: Air diffusion-veg/root                                                                                      
 ingestion..................  ..........  ..........        ..........  ..........  ..........
9: Direct soil-veg/root                                                                                         
 ingestion (on site)........  ..........  ..........                                                   
                                                              a                                        
                                                                          a   ..........  ..........  ..........
9: Overland-veg/root                                                                                            
 ingestion (on site)........  ..........  ..........        ..........  ..........  ..........
10: Air deposition-beef/milk                                                                                    
 ingestion..................  ..........  ..........     ..........  ..........  ..........  ..........
10a: Air diffusion-beef/milk                                                                                    
 ingestion..................  ..........  ..........     ..........  ..........  ..........  ..........
11: Direct soil-bee/milk                                                                                        
 ingestion (on site)........  ..........  ..........                                                   
                                                              a   ..........  ..........  ..........  ..........
11: Overland-beef/milk                                                                                          
 ingestion (off site).......  ..........  ..........     ..........  ..........  ..........  ..........
14: Groundwater-dermal                                                                                          
 (bathing)..................        ..........  ..........  ..........  ..........  ..........
17: Air diffusion-drinking                                                                                      
 water ingestion............     ..........  ..........  ..........  ..........  ..........  ..........
19: Overland-drinking water                                                                                     
 ingestion..................     ..........  ..........  ..........  ..........  ..........  ..........
20: Air deposition-drinking                                                                                     
 water ingestion............     ..........  ..........  ..........  ..........  ..........  ..........
21: Air diffusion-fish                                                                                          
 ingestion..................     ..........  ..........  ..........        ..........
23: Overland-fish ingestion.     ..........  ..........  ..........        ..........
24: Air deposition-fish                                                                                         
 ingestion..................     ..........  ..........  ..........        ..........
33: Air diffusion (SW)-beef/                                                                                    
 milk ingestion.............  ..........  ..........     ..........  ..........  ..........  ..........
35: Overland (SW)-beef/milk                                                                                     
 ingestion..................  ..........  ..........     ..........  ..........  ..........  ..........
36: Air deposition (OF/SW)-                                                                                     
 beef/milk ingestion........  ..........  ..........     ..........  ..........  ..........  ..........
37: Air diffusion (SW)-                                                                                         
 dermal (bathing)...........        ..........  ..........  ..........  ..........  ..........
38: Air deposition (OF/SW)-                                                                                     
 dermal (bathing............        ..........  ..........  ..........  ..........  ..........
42: Overland (SW)-dermal                                                                                        
 (bathing)..................        ..........  ..........  ..........  ..........  ..........
----------------------------------------------------------------------------------------------------------------
a On-site pathways for receptors other than workers are modeled only for the land application unit after        
  closure.                                                                                                      


                        Table A-4.--Summary of Ecological Receptors by Exposure Pathways                        
----------------------------------------------------------------------------------------------------------------
                                                                   Receptor                                     
           Pathway           -----------------------------------------------------------------------------------
                                Mammals      Birds      Plants    Soil fauna     Fish      Daphnids     Benthos 
----------------------------------------------------------------------------------------------------------------
3: Direct soil-soil                                                                                             
 ingestion (on site)........                                                                           
                                      a                                                                
                                                  a   ..........     ..........  ..........  ..........
3: Direct soil-soil                                                                                             
 ingestion (off site).......        ..........     ..........  ..........  ..........
4: Air deposition-soil                                                                                          
 ingestion..................        ..........     ..........  ..........  ..........
5: Direct soil-dermal soil                                                                                      
 (on site)..................  ..........  ..........        ..........  ..........  ..........
5: Direct soil-dermal soil                                                                                      
 (off site).................  ..........  ..........        ..........  ..........  ..........
6: Air deposition-dermal                                                                                        
 soil.......................  ..........  ..........        ..........  ..........  ..........
8: Air deposition-veg/root                                                                                      
 ingestion..................        ..........  ..........  ..........  ..........  ..........
8a: Air diffusion-veg                                                                                           
 ingestion..................        ..........  ..........  ..........  ..........  ..........
9: Direct soil-veg/root                                                                                         
 ingestion (on site)........        ..........  ..........  ..........  ..........  ..........
9: Overland-veg/root                                                                                            
 ingestion (off site).......        ..........  ..........  ..........  ..........  ..........
11a: Direct soil-soil fauna                                                                                     
 ingestion (on site)........        ..........  ..........  ..........  ..........  ..........
11b: Direct soil-animals                                                                                        
 ingestion (on site)........        ..........  ..........  ..........  ..........  ..........
11c: Overland-soil fauna                                                                                        
 ingestion (off site).......        ..........  ..........  ..........  ..........  ..........
11d: Overland-animals                                                                                           
 ingestion (off site).......        ..........  ..........  ..........  ..........  ..........
17: Air diffusion-drinking                                                                                      
 water ingestion............        ..........  ..........  ..........  ..........  ..........
18: Groundwater (SW)-                                                                                           
 drinking water ingestion...        ..........  ..........  ..........  ..........  ..........
19: Overland-drinking water                                                                                     
 ingestion..................        ..........  ..........  ..........  ..........  ..........
20: Air deposition-drinking                                                                                     
 water ingestion............        ..........  ..........  ..........  ..........  ..........
21: Air diffusion-fish                                                                                          
 ingestion..................        ..........  ..........     ..........  ..........
22: Groundwater (SW)-fish                                                                                       
 ingestion..................        ..........  ..........     ..........  ..........
23: Overland-fish ingestion.        ..........  ..........     ..........  ..........
24: Air deposition-fish                                                                                         
 ingestion..................        ..........  ..........     ..........  ..........
37: Air diffusion (SW)-                                                                                         
 direct contact.............  ..........  ..........  ..........  ..........         
38: Air deposition (OF/SW)-                                                                                     
 direct contact.............  ..........  ..........  ..........  ..........         
40: Groundwater (SW)-direct                                                                                     
 contact....................  ..........  ..........  ..........  ..........         

[[Page 66422]]
                                                                                                                
42: Overland (SW)-direct                                                                                        
 contact....................  ..........  ..........  ..........  ..........         
----------------------------------------------------------------------------------------------------------------
a On-site pathways are modeled only for the land application unit after closure.                                



                           Table A-5.--Pathways Modeled for Each Waste Management Unit                          
----------------------------------------------------------------------------------------------------------------
                                                                   Waste management unit                        
                                         -----------------------------------------------------------------------
                 Pathway                      Ash     Land appl.                Surface                         
                                           monofill      unit      Wastepile   impound.      Tank      Water use
----------------------------------------------------------------------------------------------------------------
1: Groundwater-ingestion................  ..........           ..........  ..........
2a: Direct air-inhalation volatiles.....  ..........              ..........
2b: Direct air-inhalation particles.....           ..........  ..........  ..........
3: Direct soil-soil ingestion...........  ..........        ..........  ..........  ..........
4: Air deposition-soil ingestion........           ..........  ..........  ..........
5: Direct soil-dermal (soil)............  ..........        ..........  ..........  ..........
6: Air deposition-dermal (soil).........           ..........  ..........  ..........
8: Air deposition-veg/root ingestion....           ..........  ..........  ..........
8a: Air diffusion-veg/root ingestion....  ..........              ..........
9: Direct soil or overland-veg/root                                                                             
 ingestion..............................  ..........        ..........  ..........  ..........
10: Air deposition-beef/milk ingestion..           ..........  ..........  ..........
10a: Air diffusion-beef/milk ingestion..  ..........              ..........
11: Direct soil or overland-beef/milk                                                                           
 ingestion..............................  ..........        ..........  ..........  ..........
14: Groundwater-dermal (bathing)........  ..........  ..........  ..........  ..........  ..........   
17: Air diffusion-drinking water                                                                                
 ingestion..............................  ..........              ..........
19: Overland-drinking water ingestion...  ..........           ..........  ..........
20: Air deposition-drinking water                                                                               
 ingestion..............................           ..........  ..........  ..........
21: Air diffusion-fish ingestion........  ..........              ..........
23: Overland-fish ingestion.............  ..........           ..........  ..........
24: Air deposition-fish ingestion.......           ..........  ..........  ..........
33: Air diffusion (SW)-beef/milk                                                                                
 ingestion..............................  ..........              ..........
35: Overland (SW)-beef/milk ingestion...  ..........           ..........  ..........
36: Air deposition (OF/SW)-beef/milk                                                                            
 ingestion..............................           ..........  ..........  ..........
37: Air diffusion (SW)-dermal (bathing).  ..........              ..........
38: Air deposition (OF/SW)-dermal                                                                               
 (bathing)..............................           ..........  ..........  ..........
42: Overland (SW)-dermal (bathing)......  ..........           ..........  ..........
----------------------------------------------------------------------------------------------------------------
OF=Overland flow.    SW=Surface water.                                                                          

Appendix B

                                                                                                                

[[Page 66423]]
                   Table B-1.--Comparison of Groundwater Modeling Results for 1000 vs. 10,000 Years Time Horizon (HQ=1 and Risk=10-6)                   
                                   [Threshold Chemical Concentrations for 1000 and 10,000 years Groundwater Modeling]                                   
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                  1000 yrs time horizon        10,000 yrs time horizon  
                                                                                             -----------------------------------------------------------
   No.      CAS No.                              Name of Chemical                             Nonwastewater*  Wastewater**  Nonwastewater*  Wastewater**
                                                                                                leach mg/l     leach mg/l     leach mg/l     leach mg/l 
--------------------------------------------------------------------------------------------------------------------------------------------------------
1........      83329  Acenaphthene..........................................................       6.30E+00       3.60E+02       4.90E+00       3.10E+01
2........      67641  Acetone (2-propanone).................................................       6.00E+00       1.56E+01       6.00E+00       1.56E+01
3........      75058  Acetonitrile (methyl cyanide).........................................       3.00E-01       7.80E-01       3.00E-01       7.80E-01
4........      98862  Acetophenone..........................................................       6.40E+00       1.68E+01       6.40E+00       1.68E+01
5........     107028  Acrolein..............................................................       1.00E+06       1.00E+06       1.00E+06       1.00E+06
6........      79061  Acrylamide #..........................................................       3.80E-05       2.80E-04       3.80E-05       2.60E-04
7........     107131  Acrylonitrile #.......................................................       3.40E-04       1.10E-03       3.40E-04       1.10E-03
8........     309002  Aldrin #..............................................................       6.70E-04       6.50E-02       3.70E-06       4.70E-03
9........     107051  Allyl Chloride........................................................  ..............  ............  ..............  ............
10.......      62533  Aniline #.............................................................       1.70E-02       5.30E-02       1.70E-02       5.30E-02
176......    7440360  Antimony..............................................................       4.57E+01       1.18E+02       5.30E-02       1.36E-01
177......    7440382  Arsenic #.............................................................       3.08E-02       7.92E-02       1.48E-04       3.84E-04
178......    7440393  Barium................................................................       1.67E+01       4.29E+01       1.55E+01       3.32E+01
12.......      71432  Benzene #.............................................................       5.40E-03       1.80E-02       5.40E-03       1.77E-02
13.......      92875  Benzidine #...........................................................       6.80E-07       2.24E-06       6.80E-07       2.24E-06
14.......      50328  Benzo[a]pyrene #......................................................       5.50E-04       5.50E-02       7.00E-06       3.60E-03
15.......     205992  Benzo[b]fluoranthene #................................................       1.10E-02       4.90E-01       6.60E-05       1.60E-02
16.......     100516  Benzyl alcohol........................................................       1.50E+01       4.00E+01       1.50E+01       3.90E+01
17.......     100447  Benzyl chloride #.....................................................       1.00E+06       1.00E+06       1.00E+06       1.00E+06
11.......      56553  Benz[a]anthracene #...................................................       1.10E-04       1.10E-02       4.30E-06       7.20E-04
179......    7440417  Beryllium #...........................................................       1.06E-03       2.72E-03       3.20E-04       8.27E-04
18.......     111444  Bis(2-chloroethyl)ether #.............................................       3.68E-04       1.92E-02       3.60E-04       6.48E-04
19.......      4E+07  Bis(2-chloroisopropyl)ether #.........................................       1.90E-03       7.90E-03       1.90E-03       7.00E-03
20.......     117817  Bis(2-ethylhexyl)phthalate #..........................................       1.80E+00       1.80E+02       1.10E-03       1.20E+01
21.......      75274  Bromodichloromethane #................................................       2.52E-03       1.05E-02       2.52E-03       8.54E-03
22.......      74839  Bromomethane..........................................................       2.87E+03       5.63E+04       2.87E+03       4.13E+04
23.......      71363  Butanol...............................................................       6.00E+00       1.56E+01       6.00E+00       1.56E+01
24.......      85687  Butyl benzyl phthalate................................................       1.10E+02       1.10E+04       6.40E+01       4.40E+02
25.......      88857  Butyl-4,6-dinitrophenol,2-sec-........................................       6.40E-02       1.92E-01       6.40E-02       1.92E-01
180......    7440439  Cadmium...............................................................       1.18E+01       3.05E+01       1.10E-01       2.40E-01
26.......      75150  Carbon disulfide......................................................       6.40E+00       2.08E+01       6.40E+00       1.84E+01
27.......      56235  Carbon tetrachloride #................................................       1.61E-03       1.40E-02       1.61E-03       1.40E-02
28.......      57749  Chlordane #...........................................................       1.50E-02       1.50E+00       1.60E-04       1.00E-01
29.......     126998  Chloro-1,3-butadiene 2-(Chloroprene)..................................  ..............  ............  ..............  ............
30.......     106478  Chloroaniline p-......................................................       1.60E-01       4.20E-01       1.60E-01       4.20E-01
31.......     108907  Chlorobenzene.........................................................       1.33E+00       4.83E+00       1.33E+00       4.76E+00
32.......     510156  Chlorobenzilate #.....................................................       7.50E-03       1.02E+00       5.70E-03       5.40E-02
33.......     124481  Chlorodibromomethane #................................................       1.80E-03       6.90E-03       1.80E-03       6.60E-03
34.......      67663  Chloroform #..........................................................       1.70E-02       5.80E-02       1.70E-02       5.70E-02
35.......      74873  Chloromethane.........................................................  ..............  ............  ..............  ............
36.......      95578  Chlorophenol 2-.......................................................       3.20E-01       9.00E-01       3.20E-01       9.00E-01
181......   16065381  Chromium (+3).........................................................       1.32E+05       3.40E+05       2.37E+04       6.12E+04
182......    7440473  Chromium (+6).........................................................       1.88E+01       4.85E+01       4.76E-01       1.24E+00
37.......     218019  Chrysene..............................................................       2.70E-02       2.90E+00       1.20E-03       1.00E-01
183......    7440508  Copper................................................................       1.32E+05       3.40E+05       1.08E+03       2.79E+03
38.......     108394  Cresol m-.............................................................       3.20E+00       8.80E+00       3.20E+00       8.40E+00
39.......      95487  Cresol o-.............................................................       3.20E+00       8.80E+00       3.20E+00       8.40E+00
40.......     106445  Cresol p-.............................................................       3.20E-01       8.80E-01       3.20E-01       8.40E-01
41.......      98828  Cumene................................................................       2.50E+00       1.50E+01       2.50E+00       1.50E+01
42.......      72548  DDD #.................................................................       2.80E+03       1.00E+06       2.80E+03      9.10E+05 

[[Page 66424]]
                                                                                                                                                        
43.......      72559  DDE #.................................................................       3.30E-02       3.30E+00       1.70E-04       2.30E-01
44.......      50293  DDT, p,p'- #..........................................................       8.40E+03       1.00E+06       5.40E-03       2.04E+01
47.......    2303164  Diallate #............................................................       4.60E-01       2.80E+03       4.60E-01       9.00E+01
48.......      53703  Dibenz[a,h]- anthracene #.............................................       2.50E-04       2.50E-02       6.30E-07       1.80E-03
49.......      96128  Dibromo-3-chloropropane1,2- #.........................................       1.14E-04       7.20E-04       1.14E-04       6.60E-04
50.......      95501  Dichlorobenzene1,2-...................................................       6.10E+00       3.00E+01       6.10E+00       3.00E+01
51.......     106467  Dichlorobenzene1,4- #.................................................       1.16E-02       6.80E-02       1.08E-02       5.60E-02
52.......      91941  Dichloro- benzidine3,3 #..............................................       7.80E-04       5.40E-03       7.20E-04       4.20E-03
53.......      75718  Dichlorodifluoromethane...............................................       1.19E+01       3.57E+01       1.19E+01       3.57E+01
54.......      75343  Dichloroethane 1,1- #.................................................       1.71E-03       9.90E-03       6.00E-05       1.60E-04
55.......     107062  Dichloroethane1,2- #..................................................       1.62E-03       9.00E-03       6.00E-05       1.60E-04
56.......     166592  Dichloroethylene cis-1,2..............................................       6.40E-01       1.72E+00       6.40E-01       1.68E+00
57.......     156605  Dichloroethylene trans-1,2............................................       1.12E+00       2.94E+00       1.12E+00       2.94E+00
58.......      75354  Dichloroethylene1,1-(Vinylidene chloride:) #..........................       1.80E-04       5.90E-04       1.80E-04       5.90E-04
59.......     120832  Dichlorophenol 2,4-...................................................       1.80E-01       6.30E-01       1.80E-01       6.20E-01
60.......      94757  Dichlorophenoxyacetic acid, 2,4-......................................       6.00E-01       1.56E+00       6.00E-01       1.56E+00
61.......      78875  Dichloropropane 1,2- #................................................       2.30E-03       2.60E-02       2.30E-03       2.30E-02
62.......      1E+07  Dichloropropene trans-1,3- #..........................................       1.15E+03       9.00E+04       1.15E+03       9.00E+04
63.......     542756  Dichloropropene 1,3-(mixture of isomers) #............................       8.50E-04       2.80E-03       8.50E-04       2.80E-03
64.......      1E+07  Dichloropropene cis-1,3- #............................................       1.15E+03       9.00E+04       1.15E+03       9.00E+04
65.......      60571  Dieldrin #............................................................       5.40E-01       2.90E+04       5.40E-01       6.80E+02
66.......      84662  Diethyl phthalate.....................................................       6.00E+01       4.50E+02       5.40E+01       1.86E+02
67.......      56531  Diethylstilbestrol #..................................................       1.20E-07       9.20E-06       6.50E-08       4.30E-07
68.......      60515  Dimethoate............................................................       7.70E-01       2.94E+01       7.70E-01       2.94E+01
69.......     119904  Dimethoxybenzidine 3,3'- #............................................       1.20E-02       3.36E-02       1.02E-02       3.36E-02
70.......     131113  Dimethyl phthalate....................................................       1.04E+03     1.1.12E+04       3.00E+01       7.80E+01
72.......     119937  Dimethylbenzidine 3,3'- #.............................................       1.89E-05       8.10E-05       1.80E-05       7.02E-05
71.......      57976  Dimethylbenz[a]anthracene 7,12-.......................................       1.20E-03       1.40E-01       2.80E-06       1.30E-02
73.......     105679  Dimethylphenol 2,4-...................................................       1.19E+00       3.78E+00       1.19E+00       3.78E+00
45.......      84742  Di-n-butyl phthalate..................................................       5.70E+01       6.30E+03       2.50E+01       2.30E+02
74.......      99650  Dinitrobenzene 1,3-...................................................       6.40E-03       1.68E-02       6.40E-03      1.68E--02
75.......      51285  Dinitrophenol 2,4-....................................................       1.05E-01       2.73E-01       1.05E-01       2.73E-01
76.......     121142  Dinitrotoluene 2,4-...................................................       1.12E-01       3.01E-01       1.12E-01       2.94E-01
77.......     606202  Dinitrotoluene 2,6-...................................................       6.40E-02       1.68E-01       6.40E-02       1.68E-01
46.......     117840  Di-n-octyl phthalate..................................................       3.10E+02       5.20E+04       1.00E-01       1.30E+03
78.......     123911  Dioxane 1,4- #........................................................       1.36E-02       4.24E-02       1.36E-02       4.24E-02
79.......     122394  Diphenylamine.........................................................       2.60E+00       1.50E+01       2.60E+00       1.50E+01
80.......     298044  Disulfoton............................................................       1.30E+01       5.80E+02       1.30E+01       4.60E+02
81.......     115297  Endosulfan(Endosulfan I and II, mixture)..............................       1.00E+00       1.26E+01       9.40E-01       6.00E+00
82.......      72208  Endrin................................................................       3.20E+01       2.70E+05       3.20E+00       6.60E+03
83.......     106898  Epichlorohydrin #.....................................................       5.40E+03       4.14E+05       5.40E+03       4.14E+05
84.......     110805  Ethoxyethanol 2-......................................................       1.50E+01       3.90E+01       1.50E+01       3.90E+01
85.......     141786  Ethyl acetate.........................................................       1.14E+02       6.00E+02       1.14E+02       3.90E+02
86.......      60297  Ethyl ether...........................................................       1.05E+01       2.73E+01       1.05E+01       2.73E+01
87.......      97632  Ethyl methacrylate....................................................       6.60E+00       6.90E+01       6.60E+00       2.40E+01
88.......      62500  Ethyl methanesulfonate #..............................................       1.17E+04       9.30E+05       1.17E+04       9.30E+05
89.......     100414  Ethylbenzene..........................................................       8.10E+00       3.90E+01       8.10E+00       3.90E+01
90.......     106934  Ethylene dibromide (1,2-Dibromoethane) #..............................       1.50E-05       4.20E-04       1.50E-05       3.60E-04
91.......      96457  Ethylene thiourea #...................................................       1.70E-04       5.30E-04       1.70E-04       5.30E-04
92.......     206440  Fluoranthene..........................................................       7.50E+00       7.80E+02       1.70E+00      2.70E+01 

[[Page 66425]]
                                                                                                                                                        
93.......      86737  Fluorene..............................................................       5.00E+00       3.90E+02       3.40E+00       2.20E+01
94.......      50000  Formaldehyde..........................................................       1.05E+01       2.73E+01       1.05E+01       2.73E+01
95.......      61486  Formic acid...........................................................       1.05E+02       2.73E+02       1.05E+02       2.73E+02
96.......     110009  Furan.................................................................       6.00E-02       1.60E-01       6.00E-02       1.56E-01
97.......     319857  HCH beta- #...........................................................       2.10E-04       1.30E-03       2.10E-04       1.30E-03
99.......     319846  HCH alpha- #..........................................................       1.10E-01       2.10E+01       1.10E-01       2.10E+01
98.......      58899  HCH (Lindane) gamma- #................................................       6.93E+01       1.19E+02       6.93E-01       1.19E+02
100......      76448  Heptachlor #..........................................................       1.00E+06       1.00E+06       1.00E-06       1.00E+06
101......    1024573  Heptachlor epoxide #..................................................       4.50E+01       3.15E+04       4.50E-01       7.83E+02
102......      87683  Hexachloro-1,3-butadene #.............................................       2.30E+02       2.10E+00       6.90E-03       8.10E+02
103......     118741  Hexachlorobenzene #...................................................       3.50E+03       3.50E+01       1.10E-04       2.23E+02
104......      77474  Hexachlorocyclopentadiene.............................................       1.00E+06       1.00E+06       1.00E-06       1.00E+06
105......      67721  Hexachloroethane #....................................................       4.02E-02        110E+00       3.30E-02       2.16E-01
106......      70304  Hexachlorophene.......................................................       1.40E-02       1.50E+00       1.40E-03       5.20E-01
107......     193395  Indeno[1,2,3-cd]pyrene................................................       4.60E-03       5.00E-01       2.40E-05       1.70E-02
108......      78831  Isobutyl alcohol......................................................       1.50E+01       3.90E+01       1.50E+01       3.90E+01
109......      78591  Isophorone #..........................................................       1.62E-01       5.49E-01       1.62E-01       5.31E-01
110......     143500  Kepone #..............................................................       5.80E-05       4.80E-03       3.20E-05       2.20E-04
184......    7439921  Lead..................................................................       1.32E+05       3.40E+05       1.16E+01       3.00E+01
185......    7439976  Mercury...............................................................       1.81E+01       4.67E+01       1.38E-01       2.96E-01
111......     126987  Methacrylonitrile.....................................................       6.00E-03       1.64E-02       6.00E-03       1.56E-02
112......      67561  Methanol..............................................................       3.00E+01       7.80E+01       3.00E+01       7.80E+01
113......      72435  Methoxychlor..........................................................       1.00E+06       1.00E+06       1.00E+06       1.00E+06
114......      78933  Methyl ethyl ketone...................................................       3.00E+01       7.80E+01       3.00E+01       7.80E+01
115......     108101  Methyl isobutyl ketone................................................       3.00E+00       8.00E+00       3.00E+00       7.80E+00
116......      80626  Methyl methacrylate...................................................       8.10E+00       8.40E+01       8.10E+00       2.82E+01
117......     298000  Methyl parathion......................................................       2.34E+01       9.90E+02       2.34E+01       7.80E+01
118......      56495  Methylcholanthrene 3- #...............................................       1.70E-03       1.70E-01       1.40E-06       1.20E-02
119......      74953  Methylene bromide.....................................................       6.80E-01       2.32E+00       1.90E-01       2.32E+00
120......      75092  Methylene Chloride #..................................................       6.80E-01       2.36E+00       1.50E-02       3.90E-02
186......    7439987  Molybdenum............................................................  ..............  ............  ..............  ............
129......      91203  Naphthalene...........................................................       2.70E+00       1.40E+01       2.70E+00       1.40E+01
187......    7440020  Nickel................................................................       9.95E+00       2.56E+01       4.89E+00       1.05E+01
130......      98953  Nitrobenzene..........................................................       3.20E-02       8.40E-02       3.20E-02       8.40E-02
131......      79469  Nitropropane 2-.......................................................  ..............  ............  ..............  ............
123......      55185  N-Nitrosodiethylamine #...............................................       1.02E-06       3.18E-06       1.02E-06       3.18E-06
124......      62759  N-Nitrosodimethylamine #..............................................       3.40E-06       1.06E-05       3.40E-06       1.06E-05
121......     924163  N-Nitroso-di-n-butylamine #...........................................       3.60E-05       1.32E-04       3.60E-05       1.22E-04
122......     621647  N-Nitroso-di-n-propylamine #..........................................       1.70E-05       5.40E-05       1.70E-05       5.30E-05
125......      86306  N-Nitrosodiphenylamine #..............................................       4.80E-02       2.60E-01       4.60E-02       2.00E-01
126......      1E+07  N-Nitrosomethylethylamine #...........................................       6.80E-06       2.16E-05       6.80E-06       2.12E-05
127......     100754  N-Nitrosopiperidine #.................................................       3.40E-06       1.06E-05       3.40E-06       1.06E-05
128......     930552  N-Nitrosopyrrolidine #................................................       6.80E-05       2.12E-04       6.80E-05       2.12E-04
132......     152169  Octamethyl pyrophosphoramide..........................................       1.05E-01       2.80E-01       1.05E-01       2.73E-01
133......      56382  Parathion (ethyl).....................................................       1.16E+04       5.60E+05       1.16E+04       4.40E+05
134......     608935  Pentachlorobenzene....................................................       1.44E+01       1.56E+03       5.70E-01       5.10E+00
135......      82688  Pentachloronitrobenzene (PCNB) #......................................       2.37E-02       2.19E+00       5.40E-03       8.10E-02
136......      87865  Pentachlorophenol #...................................................       4.20E-04       2.50E-03       4.10E-04       2.00E-03
137......     108952  Phenol................................................................       3.20E+01       8.40E+01       3.20E+01       8.40E-01
138......      62384  Phenyl mercuric acetate...............................................       4.50E-03       1.17E-02       4.50E-03       1.17E-02
139......     108452  Phenylenediamine, 1,3-................................................       3.00E-01       7.80E-01       3.00E-01       7.80E-01
140......     298022  Phorate...............................................................       1.00E+06       1.00E+06       1.00E+06       1.00E+06
141......    1336363  Polychlorinated biphenyls (Aroclors) #................................       9.10E-04       8.80E-02       4.80E-06       6.10E-03
142......      2E+07  Pronamide.............................................................       5.70E+00       2.19E+01       5.70E+00       2.13E+01
143......     129000  Pyrene................................................................       1.40E+01       1.50E+03       1.70E+00       5.40E+01
144......     110861  Pyridine..............................................................       6.00E-02       1.56E-01       6.00E-02       1.56E-01
145......      94597  Safrole #.............................................................       9.50E-04       3.80E-03       9.50E-04       3.50E-03
188......    7782492  Selenium..............................................................       1.38E+00       3.57E+00       3.57E-01       9.27E-01
189......    7440224  Silver................................................................       1.32E+00       3.40E+00       8.90E-02       1.91E-01

[[Page 66426]]
                                                                                                                                                        
146......      57249  Strychnine and salts..................................................       1.60E-02       4.50E-02       1.60E-02       4.50E-02
147......     100425  Styrene...............................................................       1.54E+01       6.51E+01       1.54E+01       6.37E+01
148......    1746016  TCDDioxin 2,3,7,8, #..................................................       2.70E-08       2.70E-06       1.80E-10       1.90E-07
149......      95943  Tetrachlorobenzene 1,2,4,5- #.........................................       6.00E-02       5.70E+00       3.20E-02    2.30E-01150
              630206  Tetrachloroethane 1,1,1,2- #..........................................       7.80E-03       7.50E-02       7.80E-03       7.50E-02
151......      79345  Tetrachloroethane 1,1,2,2- #..........................................       9.60E-03       2.92E-01       8.00E-03       2.40E-02
152......     127184  Tetrachloroethylene...................................................       6.80E-01       2.08E+00       6.80E-01       2.04E+00
153......      58902  Tetrachlorophenol 2,3,4,6-............................................       5.80E-01       1.90E+00       5.80E-01       1.90E+00
154......    3689245  Tetraethyl dithiopyrophosphate........................................       1.00E+06       1.00E+06       1.00E+06        1.00+06
190......    7440280  Thallium..............................................................       3.96E+02       1.02E+03       1.92E-02       5.00E-02
155......     108883  Toluene...............................................................       1.26E+01       4.20E+01       1.26E+01       4.13E+01
156......      95807  Toluenediamine 2,4- #.................................................       5.10E-05       1.59E-04       5.10E-05       1.59E-04
158......      95534  Toluidine o- #........................................................       6.80E-04       2.24E-03       6.80E-04       2.24E-03
157......     106490  Toluidine p- #........................................................       6.80E-04       2.24E-03       2.24E-03       2.24E-03
159......    8001352  Toxaphene (chlorinated camphenes) #...................................       1.10E-01       6.70E+02       1.10E-01       2.20E+01
160......      75252  Tribromomethane #.....................................................       1.80E-02       6.80E-02       1.80E-02       6.40E-02
161......      76131  Trichloro-1,2,2-trifluoro- ethane 1,1,2-..............................       2.40E+03        1.40E04       2.40E+03       1.10E+04
162......     120821  Trichlorobenzene 1,2,4-...............................................       2.10E+00       1.70E+02       1.30E+00       9.30E+00
163......      71556  Trichloroethane 1,1,1-................................................       5.00E+00       1.20E+02       4.60E+00       1.20E+02
164......      79005  Trichloroethane 1,1,2- #..............................................       1.80E-03       7.40E-03       1.80E-03       7.00E-03
165......      79016  Trichloroethylene (1,1,2-Trichloroethylene) #.........................       1.44E-02       5.28E-02       1.28E-02       3.84E-02
166......      75694  Trichlorofluoromethane................................................       1.60E+01        4.90+01       1.60E+01       4.80E+01
168......      95954  Trichlorophenol 2,4,5-................................................       4.20E+00       2.00E+01       4.20E+00       4.40E+01
167......      88062  Trichlorophenol 2,4,6- #..............................................       1.52E-02       5.76E-02       1.52E-02       5.36E-02
170......      93765  Trichlorophenoxyacetic acid 2,4,5-....................................       6.40E-01       1.68E+00       6.40E-01       1.68E+00
169......      93721  Trichlorophenoxypropionic acid........................................       4.80E-00       1.32E+00       4.80E-01       1.26E+00
171......      96184  Trichloropropane 1,2,3-...............................................       3.40E-01       2.20E+00       3.40E-01       1.10E+00
172......      99354  Trinitrobenzene (1,3,5-Trinitrobenzene) sym-..........................       3.00E-03       8.00E-03       3.00E-03       7.80E-03
173......     126727  Tris (2,3-dibromoprophyl) phosphate B19 #.............................       9.90E-05       2.52E-03       9.90E-05       2.52E-03
191......    7440622  Vanadium..............................................................       8.82E+00       2.27E+01       3.71E+00       9.58E+00
174......      75014  Vinyl chloride #......................................................       6.80E-05       2.16E-04       6.00E-05       1.56E-04
175......    1330297  Xylenes (total).......................................................       1.47E+02       9.10E+02       1.47E+02       8.60E+02
192......    7440666  Zinc..................................................................       1.08E+02       2.79E+02       3.84E+01       9.90E+01
--------------------------------------------------------------------------------------------------------------------------------------------------------
For Trichloroethane 1,1,1 the MCL, 0.20 mg/L was used in conic. calculation.                                                                            
                                                                                                                                                        
*Represents the lowest results from either landfills, waste piles, or land application units waste management scenarios.                                
**Represents results from surface impoundments.                                                                                                         
# Carcinogen.                                                                                                                                           



[[Page 66427]]


Appendix C

                                                  Table C-1.--Summary of Constituent-Specific Exit Level Development Using Toxicity Benchmarks                                                  
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                   WW totals (mg/l)                           NWW totals (mg/kg)                      NWW leach (mg/l)          
                                                                 -------------------------------------------------------------------------------------------------------------------------------
                                                                                                                      Multipath                                                                 
            CAS No.                            Name                Multipath  Groundwater  Extrapolated                modeled   Extrapolated              Groundwater  Extrapolated            
                                                                    modeled     modeled     exit level     WW EQC       leach     leach level    NWW EQC     modeled     each level     WW EQC  
                                                                  exit level   exit level                               level                               each level                          
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
83-32-9........................  Acenaphthene...................        49.5         31.2  ............      0.0018        9480  ............      0.0742          4.9  ............      0.0018
208-96-8.......................  Acenaphthylene.................  ..........  ...........      0.00285         0.02  ..........          3.9          0.7  ...........    0.0000661         0.02
67-64-1........................  Acetone........................      232000         15.6  ............         0.2       17400  ............       0.027            6  ............         0.2
75-05-8........................  Acetonitrile...................        6.58         0.78  ............       0.015         923  ............       0.014          0.3  ............       0.015
98-86-2........................  Acetophenone...................        5960         16.8  ............     0.00158        1210  ............        0.03          6.4  ............     0.00158
75-36-5........................  Acetyl chloride................  ..........  ...........        0.023   ..........  ..........        30.85   ..........  ...........        0.015   ..........
591-08-2.......................  Acetyl-2-thiourea,1-...........  ..........  ...........      0.11775            1  ..........         1.66           70  ...........          6.4            1
53-96-3........................  Acetylaminofluorene, 2-........  ..........  ...........      0.02762         0.02  ..........         3.28            1  ...........      0.00884         0.02
107-02-8.......................  Acrolein.......................     0.00248  ...........  ............       0.013        2.63  ............       0.075  ...........  ............       0.013
79-06-1........................  Acrylamide.....................        3.67      0.00026  ............        0.01     0.00436  ............         0.1     0.000038  ............        0.01
107-13-1.......................  Acrylonitrile..................     0.00428       0.0011  ............       0.008       0.961  ............         0.7      0.00034  ............       0.008
1402-68-2......................  Aflatoxins.....................  ..........  ...........         14.7   ..........  ..........         6900   ..........  ...........         10.5   ..........
116-06-3.......................  Aldicarb.......................  ..........  ...........    0.0069415         0.05  ..........        0.194            1  ...........         0.48         0.05
309-00-2.......................  Aldrin.........................   5.640E-07      0.00469  ............    0.000034    0.000444  ............      0.0006    3.670E-06  ............    0.000034
107-18-6.......................  Allyl alcohol..................  ..........  ...........           39   ..........  ..........        36700   ..........  ...........           15   ..........
107-05-1.......................  Allyl chloride.................      0.0742  ...........  ............       0.002         258  ............       0.002  ...........  ............       0.002
92-67-1........................  Aminobiphenyl, 4-..............  ..........  ...........      0.02762         0.02  ..........         3.28            1  ...........      0.00884         0.02
2763-96-4......................  Aminomethyl-3-isoxazolol, 5-...  ..........  ...........        0.159   ..........  ..........       19.955   ..........  ...........        0.105   ..........
504-24-5.......................  Aminopyridine, 4-..............  ..........  ...........      0.02762   ..........  ..........         3.28   ..........  ...........      0.00884   ..........
61-82-5........................  Amitrole.......................  ..........  ...........    0.0069415   ..........  ..........        0.194   ..........  ...........         0.48   ..........
62-53-3........................  Aniline........................       0.444        0.053  ............     0.00023        4.21  ............      0.0132        0.017  ............     0.00023
120-12-7.......................  Anthracene.....................  ..........  ...........      0.00285        0.007  ..........          3.9          0.5  ...........    0.0000661        0.007
7440-36-0......................  Antimony.......................        8210        0.136  ............      0.0008        8.72  ............           2        0.053  ............      0.0008
140-57-8.......................  Aramite........................  ..........  ...........         14.7         0.02  ..........         6900            1  ...........         10.5         0.02
7440-38-2......................  Arsenic........................        40.5     0.000384  ............      0.0005        0.17  ............      0.3031     0.000148  ............      0.0005
2465-27-2......................  Auramine.......................  ..........  ...........        0.159   ..........  ..........       19.955   ..........  ...........        0.105   ..........
115-02-6.......................  Azaserine......................  ..........  ...........        0.159   ..........  ..........       19.955   ..........  ...........        0.105   ..........
7440-39-3......................  Barium.........................  ..........         33.2  ............       0.001        2080  ............         0.2         15.5  ............       0.001
71-43-2........................  Benzene........................      0.0209       0.0177  ............     0.00004         109  ............      0.0001       0.0054  ............     0.00004
92-87-5........................  Benzidine......................     0.00015    2.240E-06  ............      0.0025   0.0000298  ............       0.042    6.800E-07  ............      0.0025
106-51-4.......................  Benzoquinone, p-...............  ..........  ...........         14.7         0.01  ..........         6900          0.7  ...........         10.5         0.01
98-07-7........................  Benzotrichloride...............  ..........  ...........        0.081   ..........  ..........          142        0.004  ...........       0.0317   ..........
50-32-8........................  Benzo(a)pyrene.................     0.00231      0.00364  ............    0.000023       0.227  ............      0.0621    7.040E-06  ............    0.000023
205-99-2.......................  Benzo(b)fluoranthene...........    0.000805       0.0164  ............    0.000018         3.7  ............      0.0699    0.0000661  ............    0.000018
205-82-3.......................  Benzo(j)fluoranthene...........  ..........  ...........      0.00285       0.0002  ..........          3.9         0.01  ...........    0.0000661       0.0002
207-08-9.......................  Benzo(k)fluoranthene...........  ..........  ...........      0.00285       0.0002  ..........          3.9          0.7  ...........    0.0000661       0.0002
191-24-2.......................  Benzo[g,h,i,]perylene..........  ..........  ...........      0.00285       0.0008  ..........          3.9          0.7  ...........    0.0000661       0.0008
100-51-6.......................  Benzyl alcohol.................       22500           39  ............     0.00074        2740  ............       0.034           15  ............     0.00074
100-44-7.......................  Benzyl chloride................        1.13          3.9  ............   5.000E-06        37.5  ............     0.00276           15  ............   5.000E-06
56-55-3........................  Benz(a)anthracene..............      0.0138     0.000717  ............    0.000013         0.1  ............      0.0826    4.300E-06  ............    0.000013
225-51-4.......................  Benz[c]acridine................  ..........  ...........      0.00285       0.0005  ..........          3.9         0.03  ...........    0.0000661       0.0005
7440-41-7......................  Beryllium......................        10.1     0.000827  ............     0.00003      0.0591  ............         0.1      0.00032  ............      0.0003
39638-32-9.....................  Bis (2-chloroisopropyl) ether..       0.569        0.007  ............     0.00145       0.944  ............      0.0586       0.0019  ............     0.00145
111-44-4.......................  Bis(2-chlorethyl)ether.........     0.00141     0.000648  ............      0.0003       0.115  ............      0.0651      0.00036  ............      0.0003
117-81-7.......................  Bis(2-ethylhexyl)phthalate.....     0.00044         12.4  ............     0.00027         225  ............       0.143      0.00112  ............     0.00027
542-88-1.......................  Bis(chloromethyl)either........  ..........  ...........        0.023   ..........  ..........        30.85   ..........  ...........        0.015   ..........
598-31-2.......................  Bromoacetone...................  ..........  ...........        0.023        0.005  ..........        30.85         0.03  ...........        0.015        0.005
75-27-4........................  Bromodichloromethane...........        33.3      0.00854  ............     0.00008          19  ............      0.0012      0.00252  ............     0.00008
75-25-2........................  Bromoform (Tribromomethane)....       0.178        0.064  ............      0.0002         173  ............        0.02        0.018  ............      0.0002
101-55-3.......................  Bromophenyl phenyl ether, 4-...  ..........  ...........        0.023         0.01  ..........        30.85          0.7  ...........        0.015         0.01
357-57-3.......................  Brucine........................  ..........  ...........        0.159           20  ..........       19.955   ..........  ...........        0.105           20
71-36-3........................  Butanol........................       38600         15.6  ............       0.014       18200  ............        0.23            6  ............       0.014
88-85-7........................  Butyl-4,6-dinitrophenol, 2-sec-        15.4        0.192  ............     0.00029         772  ............       0.042        0.064  ............     0.00029
                                  (Dinoseb).                                                                                                                                                    
85-68-7........................  Butylbenzylphthalate...........         235          437  ............    0.000042          87  ............       0.049           64  ............    0.000042
7440-43-9......................  Cadmium........................        1600         0.24  ............     0.00005        14.1  ............         0.2         0.11  ............     0.00005
86-74-8........................  Carbazole......................  ..........  ...........        0.159   ..........  ..........       19.955   ..........  ...........        0.105   ..........
75-15-0........................  Carbon disulfide...............       0.738         18.4  ............     0.00121         330  ............      0.0002          6.4  ............     0.00121
353-50-4.......................  Carbon oxyfluoride.............  ..........  ...........        0.023   ..........  ..........        30.85   ..........  ...........        0.015   ..........
56-23-5........................  Carbon tetrachloride...........      0.0115        0.014  ............     0.00021        8.54  ............        0.02      0.00161  ............     0.00021
75-87-6........................  Chloral........................  ..........  ...........        0.081   ..........  ..........          142   ..........  ...........       0.0317   ..........
305-03-3.......................  Chlorambucil...................  ..........  ...........        0.081   ..........  ..........          142   ..........  ...........       0.0317   ..........
57-74-9........................  Chlordane......................    0.000014       0.0998  ............     0.00004     0.00976  ............      0.0015     0.000163  ............     0.00004
494-03-1.......................  Chlomaphazin...................  ..........  ...........        0.081   ..........  ..........          142   ..........  ...........       0.0317   ..........
126-99-8.......................  Chloro-1, 3-butadiene, 2-             0.515  ...........  ............       0.002         288  ............     0.00099  ...........  ............       0.002
                                  (Chloroprene).                                                                                                                                                
107-20-0.......................  Chloroacetaldehyde.............  ..........  ...........        0.023   ..........  ..........        30.85   ..........  ...........        0.015   ..........
106-47-8.......................  Chloroaniline, p-..............         517         0.42  ............     0.00066         142  ............      0.0592         0.16  ............     0.00066
108-90-7.......................  Chlorobenzene..................         1.5         4.76  ............     0.00004        2470  ............      0.0002         1.33  ............     0.00004
510-15-6.......................  Chlorobenzilate................      0.0731        0.054  ............     0.00504        6.82  ............       0.069       0.0057  ............     0.00504
124-48-1.......................  Chlorodibromomethane...........        16.3       0.0066  ............     0.00007        27.5  ............     0.00085       0.0018  ............     0.00007
75-00-3........................  Chloroethane (ethyl chloride)..  ..........  ...........        0.023        0.005  ..........        30.85        0.005  ...........        0.015        0.005
110-75-8.......................  Chloroethyl vinyl ether, 2-....  ..........  ...........        0.081   ..........  ..........          142        0.005  ...........       0.0317   ..........
67-66-3........................  Chloroform.....................     0.00759        0.057  ............     0.00003        6.74  ............       0.002        0.017  ............     0.00003

[[Page 66428]]
                                                                                                                                                                                                
59-50-7........................  Chloro-m-cresol, p-............  ..........  ...........        0.081         0.02  ..........          142            1  ...........       0.0317         0.02
107-30-2.......................  Chloromethyl methyl ether......  ..........  ...........        0.023   ..........  ..........        30.85        0.005  ...........        0.015   ..........
91-58-7........................  Chloronaphthalene, 2-..........  ..........  ...........        0.081         0.01  ..........          142          0.7  ...........       0.0317         0.01
95-57-8........................  Chlorophenol, 2-...............         134          0.9  ............     0.00058         104  ............      0.0758         0.32  ............     0.00058
7005-72-3......................  Clorophenyl phenyl ether, 4-...  ..........  ...........        0.023         0.01  ..........        30.85          0.7  ...........        0.015         0.01
5344-82-1......................  Chlorophenyl thiourea, 1-o-....  ..........  ...........        0.023   ..........  ..........        30.85   ..........  ...........        0.015   ..........
542-76-7.......................  Chloropropionitrile, 3-........  ..........  ...........        0.081          0.1  ..........          142          0.5  ...........       0.0317          0.1
7440-47-3......................  Chromium.......................        1300         1.24  ............       0.002        9.76  ............       0.003        0.476  ............       0.002
218-01-9.......................  Chrysene.......................        1.32          0.1  ............     0.00015        34.6  ............       0.084      0.00119  ............     0.00015
6358-53-8......................  Citrus red No. 2...............  ..........  ...........         14.7   ..........  ..........         6900   ..........  ...........         10.5   ..........
7440-48-4......................  Cobalt.........................  ..........  ...........         1.24          0.5  ..........         8.72            5  ...........       0.4165          0.5
7440-50-8......................  Copper.........................         674         2790  ............      0.0007        5.91  ............         0.5         1080  ............      0.0007
108-39-4.......................  Cresol, m-.....................         615          8.4  ............     0.00046       21500  ............       0.035          3.2  ............     0.00046
95-48-7........................  Cresol, o-.....................         656          8.4  ............     0.00055       27400  ............       0.027          3.2  ............     0.00055
106-44-5.......................  Cresol, p-.....................        63.5         0.84  ............     0.00046        2550  ............       0.035         0.32  ............     0.00046
4170-30-3......................  Crotonaldehyde.................  ..........  ...........          7.8         0.06  ..........         1210            4  ...........          6.2         0.06
57-12-5........................  Cyanide........................  ..........  ...........        0.159          0.2  ..........       19.955          0.2  ...........        0.105          0.2
14901-08-7.....................  Cycasin........................  ..........  ...........         14.7   ..........  ..........         6900   ..........  ...........         10.5   ..........
108-94-1.......................  Cyclohexanone..................  ..........  ...........          7.8           10  ..........         1210           10  ...........          6.2           10
131-89-5.......................  Cyclohexyl-4,6-dinitrophenol, 2- ..........  ...........       0.0252          0.1  ..........        2.991            7  ...........       0.0083          0.1
                                  .                                                                                                                                                             
50-18-0........................  Cyclophosphamide...............  ..........  ...........        0.159   ..........  ..........       19.955   ..........  ...........        0.105   ..........
20830-81-3.....................  Daunomycin.....................  ..........  ...........         14.7   ..........  ..........         6900   ..........  ...........         10.5   ..........
72-54-8........................  DDD............................    0.000126       913000  ............     0.00005     0.00648  ............      0.0012         2800  ............     0.00005
53-19-0........................  DDD (o,p\1\)...................  ..........  ...........    0.0069415   ..........  ..........        0.194   ..........  ...........         0.48   ..........
72-55-9........................  DDE............................   9.110E-06        0.228  ............    0.000058    0.000936  ............      0.0006    0.0000623  ............    0.000058
3424-82-6......................  DDE (o,p\1\)...................  ..........  ...........    0.0069415   ..........  ..........        0.194   ..........  ...........         0.48   ..........
50-29-3........................  DDT............................   0.0000181         20.4  ............    0.000081     0.00315  ............      0.0006       0.0054  ............    0.000081
789-02-6.......................  DDT (o.p\1\)...................  ..........  ...........    0.0069415   ..........  ..........        0.194   ..........  ...........         0.48   ..........
2303-16-4......................  Diallate.......................        0.26         90.1  ............     0.00063        1.26  ............       0.023         0.46  ............     0.00063
132-64-9.......................  Dibenzofuran...................  ..........  ...........          8.4         0.01  ..........        27400          0.7  ...........          3.2         0.01
192-65-4.......................  Dibenzo[a,e]pyrene.............  ..........  ...........      0.00285       0.0002  ..........          3.9         0.01  ...........    0.0000661        0.001
189-64-0.......................  Dibenzo[a,h]pyrene.............  ..........  ...........      0.00285       0.0002  ..........          3.9         0.01  ...........    0.0000661       0.0002
189-55-9.......................  Dibenzo[a,i]pyrene.............  ..........  ...........      0.00285       0.0002  ..........          3.9         0.01  ...........    0.0000661       0.0002
194-59-2.......................  Dibenzo[c,g]carbazole, 7H-.....  ..........  ...........      0.00285         0.01  ..........          3.9          0.7  ...........    0.0000661         0.01
226-36-8.......................  Dibenz(a,h)acridine............  ..........  ...........      0.00285       0.0002  ..........          3.9         0.01  ...........    0.0000661       0.0002
53-70-3........................  Dibenz(a,h)anthracene..........   8.440E-06      0.00176  ............     0.00003    0.000155  ............       0.084    6.340E-07  ............     0.00003
224-42-0.......................  Dibenz[a,j]acridine............  ..........  ...........      0.00285        0.001  ..........          3.9          0.7  ...........    0.0000661        0.001
96-12-8........................  Dibromo-3-chloropropane, 1,2-..      0.0723      0.00066  ............     0.00026       0.663  ............      0.0003     0.000114  ............     0.00026
764-41-0.......................  Dichloro-2-butene, 1,4-........  ..........  ...........        0.023        0.005  ..........        30.85        0.005  ...........        0.015        0.005
110-57-6.......................  Dichloro-2-butene, trans-1,4-..  ..........  ...........        0.023        0.005  ..........        30.85        0.005  ...........        0.015        0.005
96-23-1........................  Dichloro-2-propanol, 1,3-......  ..........  ...........        0.081         0.01  ..........          142         0.05  ...........       0.0317         0.01
95-50-1........................  Dichlorobenzene, 1,2-..........        15.4         29.5  ............     0.00003       50000  ............      0.0002          6.1  ............     0.00003
541-73-1.......................  Dichlorobenzene, 1,3-..........  ..........  ...........        0.023        0.005  ..........        30.85          0.7  ...........        0.015        0.005
106-46-7.......................  Dichlorobenzene, 1,4-..........        3.01        0.056  ............     0.00004        63.9  ............      0.0001       0.0108  ............     0.00004
91-94-1........................  Dichlorobenzidine, 3,3 \1\-....      0.0037       0.0042  ............      0.0024      0.0524  ............       0.116      0.00072  ............      0.0024
75-71-8........................  Dichlorodifluoromethane........        14.7         35.7  ............      0.0001        8070  ............      0.0052         11.9  ............      0.0001
75-34-3........................  Dichloroethane, 1,1-...........        37.4      0.00016  ............     0.00004        24.2  ............      0.0002      0.00006  ............     0.00004
107-06-2.......................  Dichloroethane, 1,2-...........     0.00698      0.00016  ............     0.00006         6.1  ............      0.0001      0.00006  ............     0.00006
75-35-4........................  Dichloroethylene, 1,1-.........     0.00345      0.00059  ............     0.00012        2.55  ............      0.0014      0.00018  ............     0.00012
156-59-2.......................  Dichloroethylene, cis-1,2-.....       30000         1.68  ............     0.00012        5400  ............        0.02         0.64  ............     0.00012
156-60-5.......................  Dichloroethylene, trans-1,2-...       44200         2.94  ............     0.00006       13800  ............      0.0006         1.12  ............     0.00006
111-91-1.......................  Dichloromethoxy ethane.........  ..........  ...........        0.023         0.01  ..........        30.85          0.7  ...........        0.015         0.01
98-87-3........................  Dichloromethylbenzene (benzal    ..........  ...........        0.023        0.005  ..........        30.85          0.3  ...........        0.015        0.005
                                  chloride).                                                                                                                                                    
120-83-2.......................  Dichlorophenol, 2,4-...........        6.94         0.62  ............     0.00041         769  ............      0.0788         0.18  ............     0.00041
87-65-0........................  Dichlorophenol, 2,6-...........  ..........  ...........        0.023         0.01  ..........        30.85          0.7  ...........        0.015         0.01
94-75-7........................  Dichlorophenoxyacetic acid, 2,4-       58.5         1.56  ............     0.00029        3140  ............     0.00011          0.6  ............     0.00029
                                   (2,4-D).                                                                                                                                                     
78-87-5........................  Dichloropropane, 1,2-..........       0.303        0.023  ............     0.00004        16.9  ............      0.0001       0.0023  ............     0.00004
542-75-6.......................  Dichloropropene, 1,3-..........     0.00476       0.0028  ............      0.0009        32.4  ............      0.0003      0.00085  ............      0.0009
10061-01-5.....................  Dichloropropene, cis-1,3-......     0.00485        90000  ............     0.00069        2.64  ............      0.0003         1150  ............     0.00069
10061-02-6.....................  Dichloropropene, trans-1,3-....      0.0049        90000  ............     0.00094        2.67  ............      0.0003         1150  ............     0.00094
60-57-1........................  Dieldrin.......................    0.000059          682  ............    0.000044     0.00176  ............      0.0006         0.54  ............    0.000044
1464-53-5......................  Diepoxybutane, 1,2,3,4- (2,2\1\- ..........  ...........         14.7        0.005  ..........         6900        0.005  ...........         10.5        0.005
                                  bioxirane).                                                                                                                                                   
84-66-2........................  Diethyl phthalate..............        3560          186  ............     0.00025        4490  ............       0.022           54  ............     0.00025
311-45-5.......................  Diethyl-p-nitrophenyl phosphate  ..........  ...........        0.159   ..........  ..........       19.955   ..........  ...........        0.105   ..........
56-53-1........................  Diethylstibestrol..............   7.720E-07    4.290E-07  ............      0.0078   2.470E-11  ............           1    6.500E-08  ............      0.0078
94-58-6........................  Dihydrosafrole.................  ..........  ...........         14.7         0.05  ..........         6900            3  ...........         10.5         0.05
60-51-5........................  Dimethoate.....................        38.1         29.4  ............     0.00029         1.6  ............      0.0691         0.77  ............     0.00029
131-11-3.......................  Dimethyl phthalate.............      200000           78  ............     0.00064           3  ............       0.013           30  ............     0.00064
77-78-1........................  Dimethyl sulfate...............  ..........  ...........      0.11775   ..........  ..........         1.66   ..........  ...........          6.4   ..........

[[Page 66429]]
                                                                                                                                                                                                
60-11-7........................  Dimethylaminoazobenzene, p-....  ..........  ...........      0.02762         0.01  ..........         3.28          0.7  ...........      0.00884         0.01
119-93-7.......................  Dimethylbenzidine, 3,3\1\-.....    0.000625    0.0000702  ............      0.0033     0.00062  ............         0.7     0.000018  ............      0.0033
57-97-6........................  Dimethylbenz(a)anthracene, 7,12-  3.820E-06      0.00464  ............     0.00037     0.00263  ............       0.039    2.760E-06  ............     0.00037
                                  .                                                                                                                                                             
79-44-7........................  Dimethylcarbamoyl chloride.....  ..........  ...........        0.081   ..........  ..........          142   ..........  ...........       0.0317   ..........
122-09-8.......................  Dimethylphenethylamine, alpha,   ..........  ...........        0.159         0.05  ..........       19.955            3  ...........        0.105         0.05
                                  alpha-.                                                                                                                                                       
105-67-9.......................  Dimethylphenol, 2,4-...........         151         3.78  ............     0.00047       11300  ............       0.052         1.19  ............     0.00047
119-90-4.......................  Dimethyoxybenzidine, 3,3\1\-...        1.78       0.0336  ............      0.0077       0.236  ............           7       0.0102  ............      0.0077
84-74-2........................  Di-n-butyl phthalate...........         883          227  ............     0.00033       90000  ............       0.249         25.2  ............     0.00033
99-65-0........................  Dinitrobenzene, l,3-...........        1.28       0.0168  ............     0.00011        5.54  ............        0.25       0.0064  ............     0.00011
100-25-4.......................  Dinitrobenzene, l,4-...........  ..........  ...........       0.0252         0.04  ..........        2.991            3  ...........       0.0083         0.04
534-52-1.......................  Dinitro-o-cresol, 4,6-.........  ..........  ...........       0.0252         0.05  ..........        2.991            3  ...........       0.0083         0.05
51-28-5........................  Dinitrophenol, 2,4-............        50.2        0.273  ............     0.00042        56.1  ............        0.03        0.105  ............     0.00042
121-14-2.......................  Dinitrotoluene, 2,4-...........        10.7        0.294  ............     0.00002         213  ............        0.26        0.112  ............     0.00002
606-20-2.......................  Dinitrotoluene, 2,6-...........        12.9        0.168  ............     0.00031        86.3  ............        0.25        0.064  ............     0.00031
117-84-0.......................  Di-n-octyl phthalate...........       0.002         1260  ............    0.000042        4480  ............       0.139          0.1  ............    0.000042
123-91-1.......................  Dioxane, 1,4-..................         558       0.0424  ............       0.012        13.2  ............      0.0005       0.0136  ............       0.012
122-39-4.......................  Diphenylamine..................          29         14.7  ............     0.00151       11800  ............       0.041          2.6  ............     0.00151
122-66-7.......................  Diphenylhydrazine, 1,2-........  ..........  ...........        0.159         0.01  ..........       19.955          0.7  ...........        0.105         0.01
298-04-4.......................  Disulfoton.....................      0.0131          458  ............     0.00007        42.6  ............      0.0035           13  ............     0.00007
541-53-7.......................  Dithiobiuret...................  ..........  ...........      0.11775   ..........  ..........         1.66   ..........  ...........          6.4   ..........
115-29-7.......................  Endosulfan.....................        6.62            6  ............     0.00004        73.1  ............      0.0005         0.94  ............     0.00004
959-98-8.......................  Endosulfan I...................  ..........  ...........    0.0069415       0.0003  ..........        0.194        0.009  ...........         0.48       0.0003
332-13-65-9....................  Endosulfan II..................  ..........  ...........    0.0069415       0.0004  ..........        0.194        0.003  ...........         0.48       0.0004
1031-07-8......................  Endosulfan sulfate.............  ..........  ...........    0.0069415       0.0004  ..........        0.194         0.04  ...........         0.48       0.0004
145-73-3.......................  Endothall......................  ..........  ...........    0.0069415          0.1  ..........        0.194   ..........  ...........         0.48          0.1
72-20-8........................  Endrin.........................      0.0729         6550  ............     0.00039         026  ............      0.0036           32  ............     0.00039
7421-93-4......................  Endrin aldehyde................  ..........  ...........    0.0069415       0.0005  ..........        0.194         0.02  ...........         0.48       0.0005
53494-70-5.....................  Endrin ketone..................  ..........  ...........    0.0069415       0.0005  ..........        0.194         0.03  ...........         0.48       0.0005
106-89-8.......................  Epichlorohydrin................       0.335       414000  ............     0.06519          44  ............      0.0714         5400  ............     0.06519
51-43-4........................  Epinephrine....................  ..........  ...........        0.159   ..........  ..........       19.955   ..........  ...........        0.105   ..........
110-80-5.......................  Ethoxyethanol, 2-..............        14.7           39  ............        1.16        6900  ............        2.03           15  ............        1.16
141-78-6.......................  Ethyl acetate..................  ..........          390  ............       0.009      272000  ............        0.18          114  ............      0.0009
51-79-6........................  Ethyl carbamate................  ..........  ...........         14.7         0.05  ..........         6900            3  ...........         10.5         0.05
107-12-0.......................  Ethyl cyanide (propionitrile)..  ..........  ...........        0.159          0.1  ..........       19.955          0.1  ...........        0.105          0.1
60-29-7........................  Ethyl ether....................  ..........         27.3  ............     0.00153       41200  ............     0.00319         10.5  ............     0.00153
97-63-2........................  Ethyl methacrylate.............       25500           24  ............     0.00345        3420  ............      0.0011          6.6  ............     0.00345
62-50-0........................  Ethyl methanesulfonate.........      0.0055       930000  ............     0.00106       00133  ............       0.018        11700  ............     0.00106
100-41-4.......................  Ethylbenzene...................        74.5           39  ............     0.00006      550000  ............      0.0002          8.1  ............     0.00006
106-93-4.......................  Ethylene Dibromide.............    0.000928      0.00036  ............     0.00006     0.00745  ............      0.0001     0.000015  ............     0.00006
75-21-8........................  Ethylene oxide.................  ..........  ...........         14.7        0.001  ..........         6900         0.07  ...........         10.5        0.001
96-45-7........................  Ethylene thiourea..............        17.7      0.00053  ............  ..........        0.51  ............  ..........      0.00017  ............  ..........
151-56-4.......................  Ethyleneimine (aziridine)......  ..........  ...........        0.159   ..........  ..........       19.955   ..........  ...........        0.105   ..........
52-56-4........................  Famphur........................  ..........  ...........    0.0069415         0.02  ..........        0.194            1  ...........         0.48         0.02
640-19-7.......................  Fluoracetamide, 2-.............  ..........  ...........        0.023   ..........  ..........        30.85   ..........  ...........        0.015   ..........
62-74-8........................  Flouracetic acid, sodium salt..  ..........  ...........    0.0069415   ..........  ..........        0.194   ..........  ...........         0.48   ..........
206-44-0.......................  Fluoranthene...................        1580         27.5  ............     0.00021        5970  ............       0.084         1.74  ............     0.00021
86-73-7........................  Fluorene.......................        1310         22.4  ............     0.00021       89800  ............        0.08          3.4  ............     0.00021
16984-48-8.....................  Fluoride.......................  ..........  ...........            0         0.05  ..........            0   ..........  ...........            0         0.05
50-00-0........................  Formaldehyde...................      0.0158         27.3  ............      0.0232        48.8  ............           4         10.5  ............      0.0232
64-18-6........................  Formic Acid....................  ..........          273  ............         0.2      301000  ............          10          105  ............         0.2
765-34-4.......................  Glycidylaldehyde...............  ..........          7.8  ............  ..........        1210  ............  ..........          6.2  ............            
319-86-8.......................  HCH, delta-....................  ..........  ...........    0.0069415       0.0002  ..........        0.194       0.0006  ...........         0.48       0.0002
76-44-8........................  Heptachlor.....................   0.0000237  ...........  ............     0.00004        7.79  ............      0.0008  ...........  ............     0.00004
1024-57-3......................  Heptachlor epoxide.............    0.000528          783  ............    0.000032      0.0264  ............      0.0006         0.45  ............    0.000032
87-68-3........................  Hexachloro-1,3-butadiene.......     0.00788       0.0806  ............      0.0001        36.4  ............       0.046      0.00691  ............      0.0001
118-74-1.......................  Hexachlorobenzene..............    0.000424       0.0226  ............     0.00161      0.0116  ............      0.0723     0.000113  ............     0.00161
319-84-6.......................  Hexachlorocyclohexane, alpha-      0.000142           21  ............    0.000035      0.0333  ............      0.0008         0.11  ............    0.000035
                                  (alpha-BHC).                                                                                                                                                  
319-85-7.......................  Hexachlorocyclohexane, beta-       0.000445       0.0013  ............    0.000023        0.12  ............      0.0006      0.00021  ............    0.000023
                                  (beta-BHC).                                                                                                                                                   
58-89-9........................  Hexachlorocyclohexane, gamma-      0.000783          119  ............    0.000025       0.102  ............       0.002        0.693  ............    0.000025
                                  (Lindane).                                                                                                                                                    
77-47-4........................  Hexachlorocyclopentadiene......     0.00521  ...........  ............     0.00018        1450  ............       0.092  ...........  ............     0.00018
67-72-1........................  Hexachloroethane...............       0.049        0.212  ............   1.600E-06        80.6  ............      0.0206        0.033  ............   1.600E-06
70-30-4........................  Hexachlorophene................   5.150E-06       0.0521  ............       0.207   0.0000241  ............        1.87      0.00136  ............       0.207
1888-71-7......................  Hexachloropropene..............  ..........  ...........        0.081         0.01  ..........          142          0.7  ...........       0.0317         0.01
757-58-4.......................  Hexaethyl tetraphosphate.......  ..........  ...........         14.7   ..........  ..........         6900   ..........  ...........         10.5   ..........
591-78-6.......................  Hexanone, 2-...................  ..........  ...........          7.8        0.005  ..........         1210        0.005  ...........          6.2        0.005
302-01-2.......................  Hydrazine......................  ..........  ...........        0.159   ..........  ..........       19.955          0.3  ...........        0.105   ..........
193-39-5.......................  Indeno (1,2,3-cd) pyrene.......     0.00285       0.0165  ............    0.000043         3.9  ............      0.0748    0.0000241  ............    0.000043
                                                                                                                                                                                                

[[Page 66430]]
                                                                                                                                                                                                
74-88-4........................  Iodomethane....................  ..........  ...........        0.023        0.005  ..........        30.85        0.005  ...........        0.015        0.005
78-83-1........................  Isobutyl alcohol...............      180000           39  ............       0.011       55200  ............      0.0035           15  ............       0.011
465-73-6.......................  Isodrin........................  ..........  ...........    0.0069415         0.02  ..........        0.194            1  ...........         0.48         0.02
78-59-1........................  Isophorone.....................        78.6        0.531  ............        0.01         743  ............      0.0719        0.162  ............        0.01
120-58-1.......................  Isosafrole.....................  ..........  ...........         14.7         0.01  ..........         6900          0.7  ...........         10.5         0.01
143-50-0.......................  Kepone.........................   0.0000264      0.00022  ............       0.016    0.000277  ............       0.097     0.000032  ............       0.016
303-43-4.......................  Lasiocarpine...................  ..........  ...........        0.159   ..........  ..........       19.955   ..........  ...........        0.105   ..........
7439-92-1......................  Lead...........................      907000           30  ............        0.01         568  ............           2         11.6  ............        0.01
108-31-6.......................  Maleic anhydride...............  ..........  ...........         14.7   ..........  ..........         6900         0.07  ...........         10.5   ..........
123-33-1.......................  Maleic hydrazide...............  ..........  ...........        0.159         0.05  ..........       19.955            3  ...........        0.105         0.05
109-77-3.......................  Malononitrile..................  ..........  ...........        0.159          0.1  ..........       19.955          0.5  ...........        0.105          0.1
148-82-3.......................  Melphalan......................  ..........  ...........         14.7   ..........  ..........         6900   ..........  ...........         10.5   ..........
7439-97-6......................  Mercury........................         125        0.296  ............     0.00009       0.598  ............         0.1        0.138  ............     0.00009
126-98-7.......................  Methacrylonitrile..............      0.0708       0.0156  ............       0.009        8.91  ............      0.0005        0.006  ............       0.009
74-93-1........................  Methanethiol...................  ..........  ...........      0.11775   ..........  ..........         1.66   ..........  ...........          6.4   ..........
67-56-1........................  Methanol.......................  ..........           78  ............       0.021      138000  ............        0.46           30  ............       0.021
91-80-5........................  Methapyrilene..................  ..........  ...........        0.159          0.1  ..........       19.955            7  ...........        0.105          0.1
16752-77-5.....................  Methomyl.......................  ..........  ...........    0.0069415         0.05  ..........        0.194            3  ...........         0.48         0.05
72-43-5........................  Methoxychlor...................        6.73  ...........  ............    0.000086        19.4  ............      0.0057  ...........  ............    0.000086
74-83-9........................  Methyl bromide (Bromomethane)..        0.37         3.12  ............     0.00011         504  ............        0.02         0.92  ............     0.00011
74-87-3........................  Methyl chloride (Chloromethane)      0.0959  ...........  ............     0.00013        90.8  ............        0.02  ...........  ............     0.00013
78-93-3........................  Methyl ethyle ketone...........         141           78  ............        0.01      112000  ............     0.00834           30  ............        0.01
1338-23-4......................  Mehtyl ethyl ketone peroxide...  ..........  ...........          7.8   ..........  ..........         1210   ..........  ...........          6.2   ..........
60-34-4........................  Mehty hydrazine................  ..........  ...........        0.159   ..........  ..........       19.955   ..........  ...........        0.105   ..........
108-10-1.......................  Methyl isobutyl ketone.........        10.3          7.8  ............     0.00083       17000  ............     0.00315            3  ............     0.00083
80-62-6........................  Methyl methacrylate............       69900         28.2  ............       0.005       39500  ............      0.0027          8.1  ............       0.005
66-27-3........................  Methyl methanesulfonate........  ..........  ...........      0.11775         0.01  ..........         1.66          0.7  ...........          6.4         0.01
91-57-6........................  Methyl naphthalene, 2-.........  ..........  ...........      0.00285         0.01  ..........          3.9          0.7  ...........    0.0000661         0.01
298-00-0.......................  Methyl paratyhion..............       0.662           78  ............        0.01        1.43  ............      0.0691         23.4  ............        0.01
75-55-8........................  Methylaziridine, 2-............  ..........  ...........        0.159   ..........  ..........       19.955   ..........  ...........        0.105   ..........
56-49-5........................  Methylcholanthrene, 3-.........   9.880E-06       0.0117  ............        0.01    0.000128  ............       0.046    1.410E-06  ............        0.01
74-95-3........................  Methylene bromide..............       11700         2.32  ............     0.00024        8400  ............      0.0001         0.19  ............     0.00024
75-09-2........................  Methylene chloride.............       0.376        0.039  ............     0.00026         306  ............        0.02        0.015  ............     0.00026
101-14-4.......................  Methylenebis, 4,4'-(2-           ..........  ...........      0.02762   ..........  ..........         3.28   ..........  ...........      0.00884   ..........
                                  chloroaniline).                                                                                                                                               
70-25-7........................  Methyl-nitro-nitrosoguanidine    ..........  ...........        0.159   ..........  ..........       19.955   ..........  ...........        0.105   ..........
                                  (MNNG).                                                                                                                                                       
56-04-2........................  Methylthiouracil...............  ..........  ...........      0.11775   ..........  ..........         1.66   ..........  ...........          6.4   ..........
50-07-7........................  Mitomycin C....................  ..........  ...........         14.7   ..........  ..........         6900   ..........  ...........         10.5   ..........
7439-98-7......................  Molybdenum.....................      121000         1.83  ............       0.001         114  ............         0.3         1.83  ............       0.001
91-20-3........................  Naphthalene....................         385           14  ............      0.0018      120000  ............      0.0665          2.7  ............      0.0018
130-15-4.......................  Naphthoquinone, 1,4-...........  ..........  ...........         14.7         0.01  ..........         6900          0.7  ...........         10.5         0.01
86-88-4........................  Naphthyl-2-thiourea, 1-........  ..........  ...........      0.11775   ..........  ..........         1.66   ..........  ...........          6.4   ..........
134-32-7.......................  Naphthylamine, 1-..............  ..........  ...........        0.159         0.01  ..........       19.955          0.7  ...........        0.105         0.01
91-59-8........................  Naphthylamine, 2-..............  ..........  ...........        0.159         0.01  ..........       19.955          0.7  ...........        0.105         0.01
7440-02-0......................  Nickel.........................        5040         10.5  ............       0.005         106  ............           1         4.89  ............       0.005
54-11-5........................  Nicotine and salts.............  ..........  ...........        0.159         0.02  ..........       19.955            1  ...........        0.105         0.02
88-74-4........................  Nitroaniline, 2-...............  ..........  ...........      0.02762         0.05  ..........         3.28            3  ...........      0.00884         0.05
99-09-2........................  Nitroaniline, 3-...............  ..........  ...........      0.02762         0.05  ..........         3.28            3  ...........      0.00884         0.05
100-01-6.......................  Nitroaniline, 4-...............  ..........  ...........      0.02762         0.02  ..........         3.28            1  ...........      0.00884         0.02
99-95-3........................  Nitrobenzene...................       0.345        0.084  ............      0.0064        44.8  ............      0.0544        0.032  ............      0.0064
55-86-7........................  Nitrogen mustard...............  ..........  ...........        0.159   ..........  ..........       19.955   ..........  ...........        0.105   ..........
51-75-2........................  Nitrogen mustard hydrochloride   ..........  ...........        0.159   ..........  ..........       19.955   ..........  ...........        0.105   ..........
                                  salt.                                                                                                                                                         
126-85-2.......................  Nitrogen mustard N-Oxide.......  ..........  ...........        0.159   ..........  ..........       19.955   ..........  ...........        0.105   ..........
302-70-5.......................  Nitrogen mustard N-Oxide, HCI    ..........  ...........        0.159   ..........  ..........       19.955   ..........  ...........        0.105   ..........
                                  salt.                                                                                                                                                         
55-63-0........................  Nitroglycerine.................  ..........  ...........        0.159   ..........  ..........       19.955   ..........  ...........        0.105   ..........
99-55-8........................  Nitro-o-toluidine, 5-..........  ..........  ...........      0.02762         0.01  ..........         3.28          0.7  ...........      0.00884         0.01
88-75-5........................  Nitrophenol, 2-................  ..........  ...........       0.0252         0.01  ..........        2.991          0.7  ...........       0.0083         0.01
100-02-7.......................  Nitrophenol, 4-................  ..........  ...........       0.0252         0.05  ..........        2.991            3  ...........       0.0083         0.05
79-46-9........................  Nitropropane, 2-...............     0.00019  ...........  ............     0.00577       0.128  ............      0.0022  ...........  ............     0.00577
56-57-5........................  Nitroquinoline-1-oxide, 4-.....  ..........  ...........        0.159         0.04  ..........       19.955            3  ...........        0.105         0.04
55-18-5........................  Nitrosodiethylamine............   0.0000406    3.180E-06  ............       0.002     0.00064  ............           1    1.020E-06  ............       0.002
62-75-9........................  Nitrosodimethylamine...........    0.000268    0.0000106  ............      0.0006     0.00245  ............       0.074    3.400E-06  ............      0.0006
924-16-3.......................  Nitrosodi-n-butylamine.........    0.000279     0.000122  ............        0.06       0.094  ............        0.03     0.000036  ............        0.06
10595-95-6.....................  Nitrosomethylethylamine........       0.129    0.0000212  ............       0.028     0.00244  ............       0.016    6.800E-06  ............       0.028
1116-54-7......................  M-Nitrosodiethanolamine........  ..........  ...........    0.0000371         0.01  ..........     0.012875          0.7  ...........    0.0000119         0.01
621-64-7.......................  N-Nitrosodi-n-propylamine......      0.0644     0.000053  ............       0.026      0.0233  ............      0.0144     0.000017  ............       0.026
86-30-6........................  N-Nitrosodiphenylamine.........        7.54          0.2  ............        0.05        1270  ............      0.0846        0.046  ............        0.05
4549-40-0......................  N-Nitrosomethyl vinyl amine....  ..........  ...........    0.0000371   ..........  ..........     0.012875   ..........  ...........    0.0000119   ..........
59-89-2........................  N-Nitrosomorpholine............  ..........  ...........        0.159         0.05  ..........       19.955            3  ...........        0.105         0.05
759-73-9.......................  N-Nitroso-N-ethylurea..........  ..........  ...........        0.159   ..........  ..........       19.955   ..........  ...........        0.105   ..........
684-93-5.......................  N-Nitroso-N-methylurea.........  ..........  ...........        0.159         0.01  ..........       19.955          0.7  ...........        0.105        0.01 

[[Page 66431]]
                                                                                                                                                                                                
615-53-2.......................  N-Nitroso-N-methylurethane.....  ..........  ...........        0.159   ..........  ..........       19.955   ..........  ...........        0.105   ..........
16543-55-8.....................  N-Nitrosonomicotine............  ..........  ...........        0.159   ..........  ..........       19.955   ..........  ...........        0.105   ..........
100-75-4.......................  N-Nitrosopiperidine............      0.0106    0.0000106  ............     0.00135     0.00247  ............       0.033    3.400E-06  ............     0.00135
930-55-2.......................  N-Nitrosopyrrolidine...........       0.101     0.000212  ............      0.0047      0.0534  ............       0.042     0.000068  ............      0.0047
13256-22-9.....................  N-Nitrososarcosine.............  ..........  ...........        0.159   ..........  ..........       19.955   ..........  ...........        0.105   ..........
103-85-5.......................  N-Phenylthiourea...............  ..........  ...........      0.11775   ..........  ..........         1.66   ..........  ...........          6.4   ..........
1615-80-1......................  N,N-Diethylihydrazine..........  ..........  ...........        0.159   ..........  ..........       19.955   ..........  ...........        0.105   ..........
152-16-9.......................  Octamethyl- pyro- phosphoramide        7310        0.273  ............      0.0053          31  ............       0.146        0.105  ............      0.0053
20816-12-0.....................  Osmium tetroxide...............  ..........  ...........         1.24            3  ..........         8.72          200  ...........       0.4165            3
297-97-2.......................  O,O-Diethyl O-pyrazinyl          ..........  ...........      0.11775         0.02  ..........         1.66            1  ...........          6.4         0.02
                                  phosphorothioate.                                                                                                                                             
126-68-1.......................  O,O,O-Triethyl phosphorothioate  ..........  ...........      0.11775         0.05  ..........         1.66            3  ...........          6.4         0.05
123-63-7.......................  Paraldehyde....................  ..........  ...........          7.8            1  ..........         1210           70  ...........          6.2            1
56-38-2........................  Parathion......................        2.63       440000  ............      0.0005       0.128  ............       0.025        11600  ............      0.0005
608-93-5.......................  Pentachlorobenzene.............        7.86         5.15  ............    0.000038         205  ............        0.02       0.0543  ............    0.000038
76-01-7........................  Pentachloroethane..............  ..........  ...........        0.023        0.005  ..........        30.85         0.01  ...........        0.015        0.005
82-68-8........................  Pentachloronitrobenzene (PCNB).        13.9        0.081  ............        0.02        11.4  ............       0.052       0.0054  ............        0.02
87-86-5........................  Pentachlorophenol..............       0.301      0.00204  ............     0.00008        2.92  ............      0.1222      0.00041  ............     0.00008
62-44-2........................  Phenacetin.....................  ..........  ...........         14.7         0.02  ..........         6900            1  ...........         10.5         0.02
85-01-8........................  Phenanthrene...................  ..........  ...........      0.00285        0.006  ..........          3.9          0.7  ...........    0.0000661        0.006
108-95-2.......................  Phenol.........................       19300           84  ............     0.00028      163000  ............      0.2185           32  ............     0.00028
62-38-4........................  Phenyl mercuric acetate........       0.506       0.0117  ............  ..........     0.00932  ............  ..........       0.0045  ............  ..........
25265-76-3.....................  Phenylenediamines (N.O.S.).....  ..........  ...........        0.159         0.01  ..........       19.955          0.7  ...........        0.105         0.01
108-45-2.......................  Phenylenediamine, m-...........        5440         0.78  ............      0.0174         784  ............         0.7          0.3  ............      0.0174
106-50-3.......................  Phenylenediamine, p-...........  ..........  ...........        0.159         0.01  ..........       19.955          0.7  ...........        0.105         0.01
298-02-2.......................  Phorate........................       0.106  ...........  ............     0.00004         157  ............       0.002  ...........  ............     0.00004
298-06-6.......................  Phosphorodithioic acid, o-o-     ..........  ...........      0.11775   ..........  ..........         1.66   ..........  ...........          6.4   ..........
                                  diethyl ester.                                                                                                                                                
3288-58-2......................  Phosphorodithioic acid, o-o-     ..........  ...........      0.11775   ..........  ..........         1.66   ..........  ...........          6.4   ..........
                                  diethyl-s-methyl.                                                                                                                                             
2953-29-9......................  Phosphorodithioic acid,          ..........  ...........      0.11775   ..........  ..........         1.66   ..........  ...........          6.4   ..........
                                  trimethyl ester.                                                                                                                                              
85-44-9........................  Phthalic anhydride.............  ..........  ...........          132   ..........  ..........       2352.5            7  ...........         27.6   ..........
109-06-8.......................  Picoline, 2-...................  ..........  ...........        0.159        0.001  ..........       19.955         0.07  ...........        0.105        0.001
1336-36-3......................  Polychlorinated biphenyls......    0.000286      0.00614  ............      0.0005     0.00596  ............        0.04    4.810E-06  ............      0.0005
23950-58-5.....................  Pronamide......................        80.3         21.3  ............     0.00145         438  ............       0.097          5.7  ............     0.00145
1120-71-4......................  Propane sultone, 1,3-..........  ..........  ...........      0.11775   ..........  ..........         1.66   ..........  ...........          6.4   ..........
107-10-8.......................  Propylamine, n-................  ..........  ...........        0.159        0.005  ..........       19.955        0.005  ...........        0.105        0.005
51-52-5........................  Propylthiouracil...............  ..........  ...........      0.11775          0.1  ..........         1.66            7  ...........          6.4          0.1
107-19-7.......................  Propyn-1-ol, 2-................  ..........  ...........           39         0.01  ..........        36700         0.05  ...........           15         0.01
129-00-0.......................  Pyrene.........................        3040         54.1  ............     0.00027       15800  ............      0.0726         1.69  ............     0.00027
110-86-1.......................  Pyridine.......................       0.522        0.156  ............       0.011         814  ............         0.2         0.06  ............       0.011
50-55-5........................  Reserpine......................  ..........  ...........        0.159         0.05  ..........       19.955            3  ...........        0.105         0.05
108-46-3.......................  Resorcinol.....................  ..........  ...........    0.0069415          0.1  ..........        0.194            7  ...........         0.48          0.1
81-07-2........................  Saccharin and salts............  ..........  ...........        0.159   ..........  ..........       19.955   ..........  ...........        0.105   ..........
94-59-7........................  Safrole........................      0.0829       0.0035  ............      0.0021        10.5  ............       0.015      0.00095  ............      0.0021
7782-49-2......................  Selenium.......................         822        0.927  ............      0.0006        1.94  ............           5        0.357  ............      0.0006
7440-22-4......................  Silver.........................         199  ...........  ............      0.0005       0.134  ............         0.3  ...........  ............      0.0005
18883-66-4.....................  Streptozotocin.................  ..........  ...........         14.7   ..........  ..........         6900   ..........  ...........         10.5   ..........
57-24-9........................  Strychnine.....................        3.34        0.045  ............      0.0084      0.0041  ............           3        0.016  ............      0.0084
100-42-5.......................  Styrene........................        75.7         63.7  ............     0.00004      629000  ............       0.004         15.4  ............     0.00004
18496-25-8.....................  Sulfide........................  ..........  ...........            0            2  ..........            0            2  ...........            0            2
1746-01-6......................  TCDD, 2,3,7,8-.................   1.050E-09    1.880E-07  ............   1.000E-08   7.980E-06  ............   1.000E-06    1.780E-10  ............   1.000E-08
95-94-3........................  Tetrachlorobenzene, 1,2,4,5-...        14.8        0.234  ............     0.00141         168  ............       0.034       0.0317  ............     0.00141
630-20-6.......................  Tetrachloroethane, 1,1,1,2-....      0.0241        0.075  ............     0.00005         133  ............      0.0001       0.0078  ............     0.00005
79-34-5........................  Tetrachloroethane, 1,1,2,2-....      0.0037        0.024  ............      0.0002        29.3  ............      0.0002       0.0077  ............      0.0002
127-18-4.......................  Tetrachloroethylene............       15600         2.04  ............     0.00014       13300  ............      0.0007         0.68  ............     0.00014
58-90-2........................  Tetrachlorophenol, 2,3,4,6-....        2720         1.89  ............     0.00062        6150  ............        0.04         0.58  ............     0.00062
107-49-3.......................  Tetraethyl pyrophosphate.......  ..........  ...........         14.7   ..........  ..........         6900            3  ...........         10.5   ..........
3689-24-5......................  Tetraethyldithiopyrophosphate..        0.23  ...........  ............    0.000058        2.81  ............      0.0039  ...........  ............    0.000058
7440-28-0......................  Thallium (I)...................         646         0.05  ............      0.0007        5.12  ............           3       0.0192  ............      0.0007
62-55-5........................  Thioacetamide..................  ..........  ...........        0.159            1  ..........       19.955   ..........  ...........        0.105            1
39196-18-4.....................  Thiofanox......................  ..........  ...........      0.11775         0.05  ..........         1.66            3  ...........          6.4         0.05
108-98-5.......................  Thiophenol.....................  ..........  ...........      0.11775         0.02  ..........         1.66            1  ...........          6.4         0.02
79-19-6........................  Thiosemicarbazide..............  ..........  ...........      0.11775   ..........  ..........         1.66   ..........  ...........          6.4   ..........
62-56-6........................  Thiourea.......................  ..........  ...........      0.11775   ..........  ..........         1.66   ..........  ...........          6.4   ..........
137-26-8.......................  Thiram.........................  ..........  ...........    0.0069415         0.05  ..........        0.194            3  ...........         0.48         0.05
7440-31-5......................  Tin............................  ..........  ...........         1.24            8  ..........         8.72          500  ...........       0.4165            8
108-88-3.......................  Toluene........................        29.8         41.3  ............     0.00011      176000  ............      0.0002         12.6  ............     0.00011
584-84-9.......................  Toluene diisocyanate...........  ..........  ...........        0.159   ..........  ..........       19,955            7  ...........        0.105   ..........
95-80-7........................  Toluenediamine, 2,4-...........       0.211     0.000159  ............      0.0134      0.0101  ............           1     0.000051  ............      0.0134
823-40-5.......................  Toluenediamine, 2,6-...........  ..........  ...........        0.159         0.02  ..........       19.955            1  ...........        0.105         0.02

[[Page 66432]]
                                                                                                                                                                                                
496-72-0.......................  Toluenediamine, 3,4-...........  ..........  ...........        0.159         0.02  ..........       19.955            1  ...........        0.105         0.02
636-21-5.......................  Toluidine hydrochloride, o-....  ..........  ...........        0.159         0.01  ..........       19.955          0.7  ...........        0.105         0.01
95-53-4........................  Toluidine, o-..................       0.441      0.00224  ............      0.0121        2.35  ............       0.029      0.00068  ............      0.0121
106-49-0.......................  Toluidine, p-..................       0.703      0.00224  ............      0.0168       0.128  ............       0.043      0.00068  ............      0.0168
8001-35-2......................  Toxaphene......................    0.000364         21.5  ............     0.00127    0.000176  ............      0.0295         0.11  ............     0.00127
76-13-1........................  Trichloro-1,2,2-                       2210        11000  ............     0.00108  ..........  ............     0.00114         2400  ............     0.00108
                                  trifluoroethane, 1,1,2-.                                                                                                                                      
120-82-1.......................  Trichlorobenzene, 1,2,4-.......       0.685         9.31  ............      0.0002        3450  ............       0.574          1.3  ............      0.0002
71-55-6........................  Trichloroethane, 1,1,1-........        73.9          120  ............     0.00008       48200  ............      0.0002       0.0539  ............     0.00008
79-00-5........................  Trichloroethane, 1,1,2-........      0.0117        0.007  ............      0.0001        11.3  ............       0.004       0.0018  ............      0.0001
79-01-6........................  Trichloroethylene..............         138       0.0384  ............     0.00019         567  ............      0.0001       0.0128  ............     0.00019
75-69-4........................  Trichlorofluoromethane.........        51.4           48  ............     0.00008       25800  ............       0.001           16  ............     0.00008
75-70-7........................  Trichloromethanethiol..........  ..........  ...........      0.11775   ..........  ..........         1.66   ..........  ...........          6.4   ..........
95-95-4........................  Trichlorophenol, 2,4,5-........        38.8         18.1  ............     0.00049       11500  ............      0.0672          4.2  ............     0.00049
88-06-2........................  Trichlorophenol, 2,4,6-........         0.1       0.0536  ............      0.0004         124  ............      0.0785       0.0152  ............      0.0004
93-76-5........................  Trichlorophenoxyacetic acid,           15.5         1.68  ............     0.00008        63.2  ............      0.0063         0.64  ............     0.00008
                                  2,4,5- (245-T).                                                                                                                                               
93-72-1........................  Trichlorophenoxypropionic acid,        9.72         1.26  ............     0.00008        6.36  ............     0.00028         0.48  ............     0.00008
                                  2,4,5- (Silvex).                                                                                                                                              
96-18-4........................  Trichloropropane, 1,2,3-.......         707          1.1  ............     0.00032         872  ............      0.0009         0.34  ............     0.00032
99-35-4........................  Trinitrobenzene, sym-..........           3       0.0078  ............     0.00026       0.442  ............        0.25        0.003  ............     0.00026
126-72-7.......................  Tris (2,3-dibromopropyl)           0.000237      0.00252  ............      0.0245       0.357  ............       0.061     0.000099  ............      0.0245
                                  phosphate.                                                                                                                                                    
52-24-4........................  Tris (1-azridinyl) phosphine     ..........  ...........      0.11775   ..........  ..........         1.66   ..........  ...........          6.4   ..........
                                  sulfide.                                                                                                                                                      
72-57-1........................  Trypan blue....................  ..........  ...........         14.7   ..........  ..........         6900   ..........  ...........         10.5   ..........
66-75-1........................  Uracil mustard.................  ..........  ...........        0.159   ..........  ..........       19.955   ..........  ...........        0.105   ..........
7440-62-2......................  Vanadium.......................       15800         9.58  ............       0.003         250  ............           1         3.71  ............       0.003
108-05-4.......................  Vinyl acetate..................  ..........  ...........         14.7        0.005  ..........         6900        0.005  ...........         10.5        0.005
75-01-4........................  Vinyl chloride.................     0.00199     0.000156  ............     0.00017        1.23  ............      0.0017      0.00006  ............     0.00017
81-81-2........................  Warfarin.......................  ..........  ...........    0.0069415         0.05  ..........        0.194            3  ...........         0.48         0.05
1330-20-7......................  Xylenes (total)................        22.4          859  ............       0.002      172000  ............      0.0002          147  ............       0.002
7440-66-6......................  Zinc...........................       23200           99  ............       0.002         316  ............         0.3         38.4  ............       0.002
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                                                   Table C-2.--Summary of Constituent-Specific Exit Level Development Using MCL-Based Numbers                                                   
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                   WW totals (mg/l)                           NWW totals (mg/kg)                      NWW leach (mg/l)          
                                                                 -------------------------------------------------------------------------------------------------------------------------------
            CAS No.                            Name                Multipath  Groundwater                             Multipath                            Groundwater                          
                                                                    modeled     modeled    Extrapolated    WW EQC      modeled   Extrapolated    NWW EQC     modeled    Extrapolated    WW EQC  
                                                                  exit level   exit level   exit level               exit level   exit level               Leach level   Leach level            
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
83-32-9........................  Acenaphthene...................        49.5         31.2  ............      0.0018        9480  ............      0.0742          4.9  ............      0.0018
208-96-8.......................  Acenaphthylene.................  ..........  ...........      0.00285         0.02  ..........          3.9          0.7  ...........      0.00119         0.02
67-64-1........................  Acetone........................      232000         15.6  ............         0.2       17400  ............       0.027            6  ............         0.2
75-05-8........................  Acetonitrile...................        6.58         0.78  ............       0.015         923  ............       0.014          0.3  ............       0.015
98-86-2........................  Acetophenone...................        5960         16.8  ............     0.00158        1210  ............        0.03          6.4  ............     0.00158
75-36-5........................  Acetyl chloride................  ..........  ...........       0.0241   ..........  ..........        30.85   ..........  ...........       0.0115   ..........
591-08-2.......................  Acetyl-2-thiourea, 1-..........  ..........  ...........      0.11775            1  ..........         1.66           70  ...........          6.4            1
53-96-3........................  Acetylaminofluorene, 2-........  ..........  ...........      0.02762         0.02  ..........         3.28            1  ...........      0.00884         0.02
107-02-8.......................  Acrolein.......................     0.00248  ...........  ............       0.013        2.63  ............       0.075  ...........  ............       0.013
79-06-1........................  Acrylamide.....................        3.67      0.00026  ............        0.01     0.00436  ............         0.1     0.000038  ............        0.01
107-13-1.......................  Acrylonitrile..................     0.00428       0.0011  ............       0.008       0.961  ............         0.7      0.00034  ............       0.008
1402-68-2......................  Aflatoxins.....................  ..........  ...........         14.7   ..........  ..........         6900   ..........  ...........         10.5   ..........
116-06-3.......................  Aldicarb.......................  ..........  ...........    0.0069415         0.05  ..........        0.194            1  ...........         0.54         0.05
309-00-2.......................  Aldrin.........................   5.640E-07      0.00469  ............    0.000034    0.000444  ............      0.0006    3.670E-06  ............    0.000034
107-18-6.......................  Allyl alcohol..................  ..........  ...........           39   ..........  ..........        36700   ..........  ...........           15   ..........
107-05-1.......................  Allyl chloride.................      0.0742  ...........  ............       0.002         258  ............       0.002  ...........  ............       0.002
92-67-1........................  Aminobiphenyl, 4-..............  ..........  ...........      0.02762         0.02  ..........         3.28            1  ...........      0.00884         0.02
2763-96-4......................  Aminomethyl-3-isoxazolol, 5-...  ..........  ...........        0.159   ..........  ..........       19.955   ..........  ...........        0.105   ..........
504-24-5.......................  Aminopyridine, 4-..............  ..........  ...........      0.02762   ..........  ..........         3.28   ..........  ...........      0.00884   ..........
61-82-5........................  Amitrole.......................  ..........  ...........    0.0069415   ..........  ..........        0.194   ..........  ...........         0.54   ..........
62-53-3........................  Aniline........................       0.444        0.053  ............     0.00023        4.21  ............      0.0132        0.017  ............     0.00023
120-12-7.......................  Anthracene.....................  ..........  ...........      0.00285        0.007  ..........          3.9          0.5  ...........      0.00119        0.007
7440-36-0......................  Antimony.......................        8210        0.136  ............      0.0008        8.72  ............           2        0.053  ............      0.0008
140-57-8.......................  Aramite........................  ..........  ...........         14.7         0.02  ..........         6900            1  ...........         10.5         0.02
7440-38-2......................  Arsenic........................        40.5        0.384  ............      0.0005        0.17  ............      0.3031         0.15  ............      0.0005
2465-27-2......................  Auramine.......................  ..........  ...........        0.159   ..........  ..........       19.955   ..........  ...........        0.105   ..........
115-02-6.......................  Azaserine......................  ..........  ...........        0.159   ..........  ..........       19.955   ..........  ...........        0.105   ..........
7440-39-3......................  Barium.........................  ..........           28  ............       0.001        2080  ............         0.2         10.8  ............       0.001
71-43-2........................  Benzene........................      0.0209       0.0295  ............     0.00004        .109  ............      0.0001        0.009  ............     0.00004
92-87-5........................  Benzidine......................     0.00015   2.2400E-06  ............      0.0025   0.0000298  ............       0.042    6.800E-07  ............      0.0025

[[Page 66433]]
                                                                                                                                                                                                
106-51-4.......................  Benzoquinone, p-...............  ..........  ...........         14.7         0.01  ..........         6900          0.7  ...........         10.5         0.01
98-07-7........................  Benzotrichloride...............  ..........  ...........         0.27   ..........  ..........          142        0.004  ...........        0.033   ..........
50-32-8........................  Benzo(a)pyrene.................     0.00231         1.88  ............    0.000023       0.227  ............      0.0621       0.0036  ............    0.000023
205-99-2.......................  Benzo(b)fluoranthene...........    0.000805       0.0164  ............    0.000018         3.7  ............      0.0699    0.0000661  ............    0.000018
205-82-3.......................  Benzo(j)fluoranthene...........  ..........  ...........      0.00285       0.0002  ..........          3.9         0.01  ...........      0.00119       0.0002
207-08-9.......................  Benzo(k)fluoranthene...........  ..........  ...........      0.00285       0.0002  ..........          3.9          0.7  ...........      0.00119       0.0002
191-24-2.......................  Benzo[g,h,i]perylene...........  ..........  ...........      0.00285       0.0008  ..........          3.9          0.7  ...........      0.00119       0.0008
100-51-6.......................  Benzyl alochol.................       22500           39  ............     0.00074        2740  ............       0.034           15  ............     0.00074
100-44-7.......................  Benzyl chloride................        1.13          3.9  ............   5.000E-06        37.5  ............     0.00276           15  ............   5.000E-06
56-55-3........................  Benz(a)anthracene..............      0.0138     0.000717  ............    0.000013         0.1  ............      0.0826    4.300E-06  ............    0.000013
225-51-4.......................  Benz(c)acridine................  ..........  ...........      0.00285       0.0005  ..........          3.9         0.03  ...........      0.00119       0.0005
7440-41-7......................  Beryllium......................        10.1     0.000827  ............      0.0003      0.0591  ............         0.1      0.00032  ............      0.0003
39638-32-9.....................  Bis (2-chloroisoproply) ether..       0.569        0.007  ............     0.00145       0.944  ............      0.0586       0.0019  ............     0.00145
111-44-4.......................  Bis(2-chlorethyl)ether.........     0.00141     0.000648  ............      0.0003       0.115  ............      0.0651      0.00036  ............      0.0003
117-81-7.......................  Bis(2-ethylhexyl)phthalate.....     0.00044         1260  ............     0.00027         225  ............       0.143        0.108  ............     0.00027
542-88-1.......................  Bis(chloromethyl) ether........  ..........  ...........       0.0241   ..........  ..........        30.85   ..........  ...........       0.0115   ..........
598-31-2.......................  Bromoacetone...................  ..........  ...........       0.0241        0.005  ..........        30.85         0.03  ...........       0.0115        0.005
75-27-4........................  Bromodichloromethane...........        33.3      0.00854  ............     0.00008          19  ............      0.0012      0.00252  ............     0.00008
75-25-2........................  Bromoform (Tribromomethane)....       0.178        0.064  ............      0.0002         173  ............        0.02        0.018  ............      0.0002
101-55-3.......................  Bromopheynl phenyl ether, 4-...  ..........  ...........       0.0241         0.01  ..........        30.85          0.7  ...........       0.0115         0.01
357-57-3.......................  Brucine........................  ..........  ...........        0.159           20  ..........       19.955   ..........  ...........        0.105           20
71-36-3........................  Butanol........................       38600         15.6  ............       0.014       18200  ............        0.23            6  ............       0.014
88-85-7........................  Butyl-4,6-dinitrophenol, 2-sec-        15.4       0.0336  ............     0.00029         772  ............       0.042       0.0112  ............     0.00029
                                  (Dinoseb).                                                                                                                                                    
85-68-7........................  Butylbenzylphthalate...........         235          437  ............    0.000042          87  ............       0.049           64  ............    0.000042
7440-43-9......................  Cadmium........................        1600        0.038  ............     0.00005        14.1  ............         0.2        0.015  ............     0.00005
86-74-8........................  Carbazole......................  ..........  ...........        0.159   ..........  ..........       19.955   ..........  ...........        0.105   ..........
75-15-0........................  Carbon disulfide...............       0.738         18.4  ............     0.00121         330  ............      0.0002          6.4  ............     0.00121
353-50-4.......................  Carbon oxyfluoride.............  ..........  ...........       0.0241   ..........  ..........        30.85   ..........  ...........       0.0115   ..........
56-23-5........................  Carbon tetrachloride...........      0.0115          0.1  ............     0.00021        8.54  ............        0.02       0.0115  ............     0.00021
75-87-6........................  Chloral........................  ..........  ...........         0.27   ..........  ..........          142   ..........  ...........        0.033   ..........
305-03-3.......................  Chlorambucil...................  ..........  ...........         0.27   ..........  ..........          142   ..........  ...........        0.033   ..........
57-74-9........................  Chlordane......................    0.000014           24  ............     0.00004     0.00976  ............      0.0015        0.036  ............     0.00004
494-03-1.......................  Chlomaphazin...................  ..........  ...........         0.27   ..........  ..........          142   ..........  ...........        0.033   ..........
126-99-8.......................  Chloro-1,3-butadiene, 2-              0.515  ...........  ............       0.002         288  ............     0.00099  ...........  ............       0.002
                                  (Chloroprene).                                                                                                                                                
107-20-0.......................  Chloroacetaldehyde.............  ..........  ...........       0.0241   ..........  ..........        30.85   ..........  ...........       0.0115   ..........
106-47-8.......................  Chloroaniline, p-..............         517         0.42  ............     0.00066         142  ............      0.0592         0.16  ............     0.00066
108-90-7.......................  Chlorobenzene..................         1.5         0.68  ............     0.00004        2470  ............      0.0002         0.19  ............     0.00004
510-15-6.......................  Chlorobenzilate................      0.0731        0.054  ............     0.00504        6.82  ............       0.069       0.0057  ............     0.00504
124-48-1.......................  Chlorodibromomethane...........        16.3       0.0066  ............     0.00007        27.5  ............     0.00085       0.0018  ............     0.00007
75-00-3........................  Chloroethane (ethyl chloride)..  ..........  ...........       0.0241        0.005  ..........        30.85        0.005  ...........       0.0115        0.005
110-75-8.......................  Chloroethyl vinyl ether, 2-....  ..........  ...........         0.27   ..........  ..........          142        0.005  ...........        0.033   ..........
67-66-3........................  Chloroform.....................     0.00759        0.057  ............     0.00003        6.74  ............       0.002        0.017  ............     0.00003
59-50-7........................  Chloro-m-cresol, p-............  ..........  ...........         0.27         0.02  ..........          142            1  ...........        0.033         0.02
107-30-2.......................  Chloromethyl methyl ether......  ..........  ...........       0.0241   ..........  ..........        30.85        0.005  ...........       0.0115   ..........
91-58-7........................  Chloronaphthalene, 2-..........  ..........  ...........         0.27         0.01  ..........          142          0.7  ...........        0.033         0.01
95-57-8........................  Chlorophenol, 2-...............         134          0.9  ............     0.00058         104  ............      0.0758         0.32  ............     0.00058
7005-72-3......................  Chlorophenyl phenyl ether, 4-..  ..........  ...........       0.0241         0.01  ..........        30.85          0.7  ...........       0.0115         0.01
5344-82-1......................  Chlorophenyl thiourea, 1-o-....  ..........  ...........       0.0241   ..........  ..........        30.85   ..........  ...........       0.0115   ..........
542-76-7.......................  Chloropropionitrile, 3-........  ..........  ...........         0.27          0.1  ..........          142          0.5  ...........        0.033          0.1
7440-47-3......................  Chromium.......................        1300        0.618  ............       0.002        9.76  ............       0.003        0.238  ............       0.002
218-01-9.......................  Chrysene.......................        1.32          0.1  ............     0.00015        34.6  ............       0.084      0.00119  ............     0.00015
6358-53-8......................  Citrus red No. 2...............  ..........  ...........         14.7   ..........  ..........         6900   ..........  ...........         10.5   ..........
7440-48-4......................  Cobalt.........................  ..........  ...........        0.618          0.5  ..........         8.72            5  ...........        0.194          0.5
7440-50-8......................  Copper.........................         674         2790  ............      0.0007        5.91  ............         0.5         1080  ............      0.0007
108-39-4.......................  Cresol, m-.....................         615          8.4  ............     0.00046       21500  ............       0.035          3.2  ............     0.00046
95-48-7........................  Cresol, o-.....................         656          8.4  ............     0.00055       27400  ............       0.027          3.2  ............     0.00055
106-44-5.......................  Cresol, p-.....................        63.5         0.84  ............     0.00046        2550  ............       0.035         0.32  ............     0.00046
4170-30-3......................  Crotonaldehyde.................  ..........  ...........          7.8         0.06  ..........         1210            4  ...........          6.2         0.06
57-12-5........................  Cyanide........................  ..........  ...........        0.159          0.2  ..........       19.955          0.2  ...........        0.105          0.2
14901-08-7.....................  Cycasin........................  ..........  ...........         14.7   ..........  ..........         6900   ..........  ...........         10.5   ..........
108-94-1.......................  Cyclohexanone..................  ..........  ...........          7.8           10  ..........         1210           10  ...........          6.2           10
131-89-5.......................  Cyclohexyl-4,6-dinitrophenol, 2- ..........  ...........       0.0252          0.1  ..........        2.991            7  ...........       0.0083          0.1
                                  .                                                                                                                                                             
50-18-0........................  Cyclophosphamide...............  ..........  ...........        0.159   ..........  ..........       19.955   ..........  ...........        0.105   ..........
20830-81-3.....................  Daunomycin.....................  ..........  ...........         14.7   ..........  ..........         6900   ..........  ...........         10.5   ..........
72-54-8........................  DDD............................    0.000126       913000  ............     0.00005     0.00648  ............      0.0012         2800  ............     0.00005
53-19-0........................  DDD (o,p').....................  ..........  ...........    0.0069415   ..........  ..........        0.194   ..........  ...........         0.54   ..........
72-55-9........................  DDE............................   9.110E-06        0.228  ............    0.000058    0.000936  ............      0.0006    0.0000623  ............    0.000058
3424-82-6......................  DDE (o,p').....................  ..........  ...........    0.0069415   ..........  ..........        0.194   ..........  ...........         0.54   ..........

[[Page 66434]]
                                                                                                                                                                                                
50-29-3........................  DDT............................   0.0000181         20.4  ............    0.000081     0.00315  ............      0.0006       0.0054  ............    0.000081
789-02-6.......................  DDT (o,p').....................  ..........  ...........    0.0069415   ..........  ..........        0.194   ..........  ...........         0.54   ..........
2303-16-4......................  Diallate.......................        0.26         90.1  ............     0.00063        1.26  ............       0.023         0.46  ............     0.00063
132-64-9.......................  Dibenzofuran...................  ..........  ...........          8.4         0.01  ..........        27400          0.7  ...........          1.8         0.01
192-65-4.......................  Dibenzo[a,e]pyrene.............  ..........  ...........      0.00285        0.001  ..........          3.9          0.7  ...........      0.00119        0.001
189-64-0.......................  Dibenzo[a,h]pyrene.............  ..........  ...........      0.00285       0.0002  ..........          3.9         0.01  ...........      0.00119       0.0002
189-55-9.......................  Dibenzo[a,i]pyrene.............  ..........  ...........      0.00285       0.0002  ..........          3.9         0.01  ...........      0.00119       0.0002
194-59-2.......................  Dibenzo[c,g]carbazole, 7H-.....  ..........  ...........      0.00285         0.01  ..........          3.9          0.7  ...........      0.00119         0.01
226-36-8.......................  Dibenz(a,h)acridine............  ..........  ...........      0.00285       0.0002  ..........          3.9         0.01  ...........      0.00119       0.0002
53-70-3........................  Dibenz(a,h)anthracene..........   8.440E-06      0.00176  ............     0.00003    0.000155  ............       0.084    6.340E-07  ............     0.00003
                  224-42-0.....  Dibenz[a,j]acridine............  ..........  ...........      0.00285        0.001  ..........          3.9          0.7  ...........      0.00119        0.001
                  96-12-8......  Dibromo-3-chloropropane, 1,2-..      0.0723       0.0022  ............     0.00026       0.663  ............      0.0003      0.00038  ............     0.00026
                  864-41-0.....  Dichloro-2-butene, 1,4-........  ..........  ...........       0.0241        0.005  ..........        30.85        0.005  ...........       0.0115        0.005
                  110-57-6.....  Dichloro-2-butene, trans-1,4-..  ..........  ...........       0.0241        0.005  ..........        30.85        0.005  ...........       0.0115        0.005
                  96-23-1......  Dichloro-2-propanol, 1,3-......  ..........  ...........         0.27         0.01  ..........          142         0.05  ...........        0.033         0.01
                  95-50-1......  Dichlorobenzene, 1,2-..........        15.4          7.8  ............     0.00003       50000  ............      0.0002         1.62  ............     0.00003
                  541-73-1.....  Dichlorobenzene, 1,3-..........  ..........  ...........       0.0241        0.005  ..........        30.85          0.7  ...........       0.0115        0.005
                  106-46-7.....  Dichlorobenzene, 1,4-..........        3.01         1.12  ............     0.00004        63.9  ............      0.0001        0.216  ............     0.00004
                  91-94-1......  Dichlorobenzidine, 3,3'-.......      0.0037       0.0042  ............      0.0024      0.0524  ............       0.116      0.00072  ............      0.0024
                  75-71-8......  Dichlorodiflouromethane........        14.7         35.7  ............      0.0001        8070  ............      0.0052         11.9  ............      0.0001
                  75-34-3......  Dichloroethane, 1,1-...........        37.4      0.00016  ............     0.00004        24.2  ............      0.0002      0.00006  ............     0.00004
                  107-06-2.....  Dichloroethane, 1,2-...........     0.00698       0.0475  ............     0.00006         6.1  ............      0.0001        0.009  ............     0.00006
                  75-35-4......  Dichloroethylene, 1,1-.........     0.00345       0.0413  ............     0.00012        2.55  ............      0.0014       0.0216  ............     0.00012
                  156-59-2.....  Dichloroethylene, cis-1,2-.....       30000        0.294  ............      000012        5400  ............        0.02        0.112  ............     0.00012
                  156-60-5.....  Dichloroethylene, trans-1,2-...       44200         0.42  ............     0.00006       13800  ............      0.0006         0.16  ............     0.00006
                  111-91-1.....  Dichloromethoxyethane..........  ..........  ...........       0.0241         0.01  ..........        30.85          0.7  ...........       0.0115         0.01
                  98-87-3......  Dichloromethylbenezene (benzal   ..........  ...........       0.0241        0.005  ..........        30.85          0.3  ...........       0.0115        0.005
                                  chloride).                                                                                                                                                    
                  120-83-2.....  Dichlorophenol, 2,4-...........        6.94         0.62  ............     0.00041         769  ............      0.0788         0.18  ............     0.00041
                  87-65-0......  Dichlorophenol, 2,6-...........  ..........  ...........       0.0241         0.01  ..........        30.85          0.7  ...........       0.0115         0.01
                  94-75-7......  Dichlorophenoxyacetic acid, 2,4-       58.5        0.273  ............     0.00029        3140  ............     0.00011        0.105  ............     0.00029
                                   (2,4-D).                                                                                                                                                     
                  78-87-5......  Dichloropropane, 1,2-..........       0.303        0.115  ............     0.00004        16.9  ............      0.0001       0.0115  ............     0.00004
                  542-75-6.....  Dichloropropene, 1,3-..........     0.00476       0.0028  ............      0.0009        32.4  ............      0.0003      0.00085  ............      0.0009
                  10061-91-5...  Dichloropropene, cis-1,3-......     0.00485        90000  ............     0.00069        2.64  ............      0.0003         1150  ............     0.00069
                  10061-02-6...  Dichloropropene, trans-1,3-....      0.0049        90000  ............     0.00094        2.67  ............      0.0003         1150  ............     0.00094
                  60-57-1......  Dieldrin.......................    0.000059          682  ............    0.000044     0.00176  ............      0.0006         0.54  ............    0.000044
                  1464-53-5....  Diepoxybutane, 1,2,3,4- (2,2'-   ..........  ...........         14.7        0.005  ..........         6900        0.005  ...........         10.5        0.005
                                  bioxirane.                                                                                                                                                    
                  84-66-2......  Diethl phthalate...............        3560          186  ............     0.00025        4490  ............       0.022           54  ............     0.00025
                  311-45-5.....  Diethyl-p-nitrophenyl phosphate  ..........  ...........        0.159   ..........  ..........       19.955   ..........  ...........        0.105   ..........
                  56-53-1......  Diethylstillbestrol............   7.710E-07   4.2900E-07  ............      0.0078   2.470E-11  ............           1    6.500E-08  ............      0.0078
                  94-58-6......  Dihydrosafrole.................  ..........  ...........         14.7         0.05  ..........         6900            3  ...........         10.5         0.05
                  60-51-5......  Dimethoate.....................        38.1         29.4  ............     0.00029         1.6  ............      0.0691         0.77  ............     0.00029
                  131-11-3.....  Dimethyl phthalate.............      200000           78  ............     0.00064           3  ............       0.013           30  ............     0.00064
                  77-78-1......  Dimethyl sulfate...............  ..........  ...........      0.11775   ..........  ..........         1.66   ..........  ...........          6.4           60
                  60-11-7......  Dimethylaminoazobenzene, p-....  ..........  ...........      0.02762         0.01  ..........         3.28          0.7  ...........      0.00884         0.01
                  119-93-7.....  Dimethylbenzidine, 3,3'-.......    0.000625    0.0000702  ............      0.0033     0.00062  ............         0.7     0.000018  ............      0.0033
                  57-97-6......  Dimethylbenz(a)anthracene, 7,12-  3.820E-06      0.00464  ............     0.00037     0.00263  ............       0.039    2.760E-06  ............     0.00037
                                  .                                                                                                                                                             
79-44-7........................  Dimethylcarbamoyl chloride.....  ..........  ...........         0.27   ..........  ..........          142   ..........  ...........        0.033   ..........
122-09-8.......................  Dimethylphenethylamine, alpha,   ..........  ...........        0.159         0.05  ..........       19.955            3  ...........        0.105         0.05
                                  alpha-.                                                                                                                                                       
105-67-9.......................  Dimethylphenol,2,4-............         151         3.78  ............     0.00047       11300  ............       0.052         1.19  ............     0.00047
119-90-4.......................  Dimethyloxybenzidine,3,3'-.....        1.78       0.0336  ............      0.0077       0.236  ............           7       0.0102  ............      0.0077
84-74-2........................  Di-n-butyl phthalate...........         883          900  ............     0.00033       90000  ............       0.249          100  ............     0.00033
99-65-0........................  Dinitrobenzene,1,3-............        1.28       0.0168  ............     0.00011        5.54  ............        0.25       0.0064  ............     0.00011
100-25-4.......................  Dinitrobenzene,1,4-............  ..........  ...........       0.0252         0.04  ..........        2.991            3  ...........       0.0083         0.04
534-52-1.......................  Dinitro-o-cresol,4,6-..........  ..........  ...........       0.0252         0.05  ..........        2.991            3  ...........       0.0083         0.05
51-28-5........................  Dinitrophenol,2,4-.............        50.2        0.273  ............     0.00042        56.1  ............        0.03        0.105  ............     0.00042
121-14-2.......................  Dinitrotoluene,2,4-............        10.7        0.294  ............     0.00002         213  ............        0.26        0.112  ............     0.00002
606-20-2.......................  Dinitrotoluene,2,6-............        12.9        0.168  ............     0.00031        86.3  ............        0.25        0.064  ............     0.00031
117-84-0.......................  Di-n-octyl phthalate...........       0.002         1260  ............    0.000042        4480  ............       0.139          0.1  ............    0.000042
123-91-1.......................  Dioxane,1,4-...................         558       0.0424  ............       0.012        13.2  ............      0.0005       0.0136  ............       0.012
122-39-4.......................  Diphenylamine..................          29         14.7  ............     0.00151       11800  ............       0.041          2.6  ............     0.00151
122-66-7.......................  Diphenylhydrazine,1,2-.........  ..........  ...........        0.159         0.01  ..........       19.955          0.7  ...........        0.105         0.01
298-04-4.......................  Disulfoton.....................      0.0131          458  ............     0.00007        42.6  ............      0.0035           13  ............     0.00007
541-53-7.......................  Dithiobiuret...................  ..........  ...........      0.11775   ..........  ..........         1.66   ..........  ...........          6.4   ..........
115-29-7.......................  Endosulfan.....................        6.62            6  ............     0.00004        73.1  ............      0.0005         0.94  ............     0.00004
959-98-8.......................  Endosulfan I...................  ..........  ...........    0.0069415       0.0003  ..........        0.194        0.009  ...........         0.54       0.0003
33213-65-9.....................  Endosulfan II..................  ..........  ...........    0.0069415       0.0004  ..........        0.194        0.003  ...........         0.54      0.0004 

[[Page 66435]]
                                                                                                                                                                                                
1031-07-8......................  Endosulfan sulfate.............  ..........  ...........    0.0069415       0.0004  ..........        0.194         0.04  ...........         0.54       0.0004
145-73-3.......................  Endothall......................  ..........  ...........    0.0069415          0.1  ..........        0.194   ..........  ...........         0.54          0.1
72-20-8........................  Endrin.........................      0.0729         4800  ............     0.00039        0.26  ............      0.0036           24  ............     0.00039
7421-93-4......................  Endrin aldehyde................  ..........  ...........    0.0069415       0.0005  ..........        0.194         0.02  ...........         0.54       0.0005
53494-70-5.....................  Endrin ketone..................  ..........  ...........    0.0069415       0.0005  ..........        0.194         0.03  ...........         0.54       0.0005
106-89-8.......................  Epichlorohydrin................       0.335       414000  ............     0.06519          44  ............      0.0714         5400  ............     0.06519
51-43-4........................  Epinephrine....................  ..........  ...........        0.159   ..........  ..........       19.955   ..........  ...........        0.105   ..........
110-80-5.......................  Ethoxyethanol,2-...............        14.7           39  ............        1.16        6900  ............        2.03           15  ............        1.16
141-78-6.......................  Ethyl acetate..................  ..........          390  ............       0.009      272000  ............        0.18          114  ............       0.009
51-79-6........................  Ethyl carbamate................  ..........          390         14.7         0.05  ..........         6900            3  ...........         10.5         0.05
107-12-0.......................  Ethyl cyanide (propionitrile)..  ..........  ...........        0.159          0.1  ..........       19.955          0.1  ...........        0.105          0.1
60-29-7........................  Ethyl ether....................  ..........         27.3  ............     0.00153       41200  ............     0.00319         10.5  ............     0.00153
97-63-2........................  Ethyl methacrylate.............       25500           24  ............     0.00345        3420  ............      0.0011          6.6  ............     0.00345
62-50-0........................  Ethyl methanesulfonate.........      0.0055       930000  ............     0.00106     0.00133  ............       0.018        11700  ............     0.00106
100-41-4.......................  Ethylbenzene...................        74.5          8.4  ............     0.00006      550000  ............      0.0002         1.75  ............     0.00006
106-93-4.......................  Ethylene Dibromide.............    0.000928        0.018  ............     0.00006     0.00745  ............      0.0001      0.00075  ............     0.00006
75-21-8........................  Ethylene oxide.................  ..........  ...........         14.7        0.001  ..........         6900         0.07  ...........         10.5        0.001
96-45-7........................  Ethylene thiourea..............        17.7      0.00053  ............  ..........        0.51  ............  ..........      0.00017  ............  ..........
151-56-4.......................  Ethyleneimine (azirindine).....  ..........  ...........        0.159   ..........  ..........       19.955   ..........  ...........        0.105   ..........
52-85-7........................  Famphur........................  ..........  ...........    0.0069415         0.02  ..........        0.194            1  ...........         0.54         0.02
640-19-7.......................  Fluoracetamide, 2-.............  ..........  ...........       0.0241   ..........  ..........        30.85   ..........  ...........       0.0115   ..........
62-74-8........................  Fluoracetic acid, sodium salt..  ..........  ...........    0.0069415   ..........  ..........        0.194   ..........  ...........         0.54   ..........
206-44-0.......................  Fluoranthene...................        1580         27.5  ............     0.00021        5970  ............       0.084         1.74  ............     0.00021
86-73-7........................  Fluorene.......................        1310         22.4  ............     0.00021       89800  ............        0.08          3.4  ............     0.00021
16984-48-8.....................  Fluoride.......................  ..........  ...........            0         0.05  ..........            0   ..........  ...........            0         0.05
50-00-0........................  Formaldehyde...................      0.0158         27.3  ............      0.0232        48.8  ............           4         10.5  ............      0.0232
64-18-6........................  Formic Acid....................  ..........          273  ............         0.2      301000  ............          10          105  ............         0.2
765-34-4.......................  Glycidylaldehyde...............  ..........  ...........          7.8   ..........  ..........         1210   ..........  ...........          6.2   ..........
319-86-8.......................  HCH, delta-....................  ..........  ...........    0.0069415       0.0002  ..........        0.194       0.0006  ...........         0.54       0.0002
76-44-8........................  Heptachlor.....................   0.0000237  ...........  ............     0.00004        7.79  ............      0.0008  ...........  ............     0.00004
1024-57-3......................  Heptachlor epoxide.............    0.000528        17400  ............    0.000032      0.0264  ............      0.0006           66  ............    0.000032
87-68-3........................  Hexachloro-1,3-butadiene.......     0.00788       0.0806  ............      0.0001        36.4  ............       0.046      0.00691  ............      0.0001
118-74-1.......................  Hexachlorobenzene..............    0.000424          3.6  ............     0.00161      0.0116  ............      0.0723        0.018  ............     0.00161
319-84-6.......................  Hexachlorocyclohexane, alpha-      0.000142           21  ............    0.000035      0.0333  ............      0.0008         0.11  ............    0.000035
                                  (alpha-BHC).                                                                                                                                                  
319-85-7.......................  Hexachlorocyclohexane, beta-       0.000445       0.0013  ............    0.000023        0.12  ............      0.0006      0.00021  ............    0.000023
                                  (beta-BHC).                                                                                                                                                   
58-89-9........................  Hexachlorocyclohexane, gamma-      0.000783          340  ............    0.000025       0.102  ............       0.002         1.98  ............    0.000025
                                  (Lindane).                                                                                                                                                    
77-47-4........................  Hexachlorocyclopentadiene......     0.00521  ...........  ............     0.00018        1450  ............       0.092  ...........  ............     0.00018
67-72-1........................  Hexachloroethane...............       0.049        0.212  ............   1.600E-06        80.6  ............      0.0206        0.033  ............   1.600E-06
70-30-4........................  Hexachlorophene................   5.150E-06       0.0521  ............       0.207   0.0000241  ............        1.87      0.00136  ............       0.207
1888-71-7......................  Hexachloropropene..............  ..........  ...........         0.27         0.01  ..........          142          0.7  ...........        0.033         0.01
757-58-4.......................  Hexaethyl tetraphosphate.......  ..........  ...........         14.7   ..........  ..........         6900   ..........  ...........         10.5   ..........
591-78-6.......................  Hexanone, 2-...................  ..........  ...........          7.8        0.005  ..........         1210        0.005  ...........          6.2        0.005
302-01-2.......................  Hydrazine......................  ..........  ...........        0.159   ..........  ..........       19.955          0.3  ...........        0.105   ..........
193-39-5.......................  Indeno(1,2,3-cd) pyrene........     0.00285       0.0165  ............    0.000043         3.9  ............      0.0748    0.0000241  ............    0.000043
74-88-4........................  Iodomethane....................  ..........  ...........       0.0241        0.005  ..........        30.85        0.005  ...........       0.0115        0.005
78-83-1........................  Isobutyl alcohol...............      180000           39  ............       0.011       55200  ............      0.0035           15  ............       0.011
465-73-6.......................  Isodrin........................  ..........  ...........    0.0069415         0.02  ..........        0.194            1  ...........         0.54         0.02
78-59-1........................  Isophorone.....................        78.6        0.531  ............        0.01         743  ............      0.0719        0.162  ............        0.01
120-58-1.......................  Isosafrole.....................  ..........  ...........         14.7         0.01  ..........         6900          0.7  ...........         10.5         0.01
143-50-0.......................  Kepone.........................   0.0000264      0.00022  ............       0.016    0.000277  ............       0.097     0.000032  ............       0.016
303-43-4.......................  Lasiocarpine...................  ..........  ...........        0.159   ..........  ..........       19.955   ..........  ...........        0.105   ..........
7439-92-1......................  Lead...........................      907000           30  ............        0.01         568  ............           2           12  ............        0.01
108-31-6.......................  Maleic anhydride...............  ..........  ...........         14.7   ..........  ..........         6900         0.07  ...........         10.5   ..........
123-33-1.......................  Maleic hydrazide...............  ..........  ...........        0.159         0.05  ..........       19.955            3  ...........        0.105         0.05
109-77-3.......................  Malononitrile..................  ..........  ...........        0.159          0.1  ..........       19.955          0.5  ...........        0.105          0.1
148-82-3.......................  Melphalan......................  ..........  ...........         14.7   ..........  ..........         6900   ..........  ...........         10.5   ..........
7439-97-6......................  Mercury........................         125       0.0596  ............     0.00009       0.598  ............         0.1        0.023  ............     0.00009
126-98-7.......................  Methacrylonitrile..............      0.0708       0.1056  ............       0.009        8.91  ............      0.0005        0.006  ............       0.009
74-93-1........................  Methanethiol...................  ..........  ...........      0.11775   ..........  ..........         1.66   ..........  ...........          6.4   ..........
67-56-1........................  Methanol.......................  ..........           78  ............       0.021      138000  ............        0.46           30  ............       0.021
91-80-5........................  Methapyrilene..................  ..........  ...........        0.159          0.1  ..........       19.955            7  ...........        0.105          0.1
16752-77-5.....................  Methomyl.......................  ..........  ...........    0.0069415         0.05  ..........        0.194            3  ...........         0.54         0.05
72-43-5........................  Methoxychlor...................        6.73  ...........  ............    0.000086        19.4  ............      0.0057  ...........  ............    0.000086
74-83-9........................  Methyl bromide (Bromomethane)..        0.37         3.12  ............     0.00011         504  ............        0.02         0.92  ............     0.00011
74-87-3........................  Methyl chloride (Chloromethane)      0.0959  ...........  ............     0.00013        90.8  ............        0.02  ...........  ............     0.00013
78-93-3........................  Methyl ethyl ketone............         141           78  ............        0.01      112000  ............     0.00834           30  ............        0.01
1338-23-4......................  Methyl ethyl ketone peroxide...  ..........  ...........          7.8   ..........  ..........         1210   ..........  ...........          6.2   ..........
60-34-4........................  Methyl hydrazine...............  ..........  ...........        0.159   ..........  ..........       19.955   ..........  ...........        0.105   ..........

[[Page 66436]]
                                                                                                                                                                                                
108-10-1.......................  Methyl isobutyl ketone.........        10.3          7.8  ............     0.00083       17000  ............     0.00315            3  ............     0.00083
80-62-6........................  Methyl methacrylate............       69900         28.2  ............       0.005       39500  ............      0.0027          8.1  ............       0.005
66-27-3........................  Methyl methanesulfonate........  ..........  ...........      0.11775         0.01  ..........         1.66          0.7  ...........          6.4         0.01
91-57-6........................  Methyl naphthalene, 2-.........  ..........  ...........      0.00285         0.01  ..........          3.9          0.7  ...........      0.00119         0.01
298-00-0.......................  Methyl parathion...............       0.662           78  ............        0.01        1.43  ............       0.691         23.4  ............        0.01
75-55-8........................  Methylazinidine, 2-............  ..........  ...........        0.159   ..........  ..........       19.955   ..........  ...........        0.105   ..........
56-49-5........................  Methylcholanthrene, 3-.........   9.880E-06       0.0117  ............        0.01    0.000128  ............       0.046    1.410E-06  ............        0.01
74-95-3........................  Methylene bromide..............       11700        0.029  ............     0.00024        8400  ............      0.0001       0.0085  ............     0.00024
75-09-2........................  Methylene chloride.............       0.376        0.039  ............     0.00026         306  ............        0.02         0.09  ............     0.00026
101-14-4.......................  Methylenegbis, 4,4'-(2-          ..........  ...........      0.02762   ..........  ..........         3.28   ..........  ...........      0.00884   ..........
                                  chloraoniline).                                                                                                                                               
70-25-7........................  Methyl-nitro-nitrosoguanidine    ..........  ...........        0.159   ..........  ..........       19.955   ..........  ...........        0.105   ..........
                                  (MNNG).                                                                                                                                                       
56-04-2........................  Methylthiouracil...............  ..........  ...........      0.11775   ..........  ..........         1.66   ..........  ...........          6.4   ..........
50-07-7........................  Mitomycin C....................  ..........  ...........         14.7   ..........  ..........         6900   ..........  ...........         10.5   ..........
7439-98-7......................  Molybdenum.....................      121000         1.83  ............       0.001         114  ............         0.3         1.83  ............       0.001
91-20-3........................  Naphthalene....................         385           14  ............      0.0018      120000  ............      0.0665          2.7  ............      0.0018
130-15-4.......................  Naphthoquinone, 1,4-...........  ..........  ...........         14.7         0.01  ..........         6900          0.7  ...........         10.5         0.01
86-88-4........................  Naphthyl-2-thiourea, 1-........  ..........  ...........      0.11775   ..........  ..........         1.66   ..........  ...........          6.4   ..........
134-32-7.......................  Naphthylamine, 1-..............  ..........  ...........        0.159         0.01  ..........       19.995          0.7  ...........        0.105         0.01
91-59-8........................  Naphthylamine, 2-..............  ..........  ...........        0.159         0.01  ..........       19.955          0.7  ...........        0.105         0.01
7440-02-0......................  Nickel.........................        5040         4.38  ............       0.005         106  ............           1         2.04  ............       0.005
54-11-5........................  Nicotine and salts.............  ..........  ...........        0.159         0.02  ..........       19.955            1  ...........        0.105         0.02
88-74-4........................  Nitroaniline, 2-...............  ..........  ...........      0.02762         0.05  ..........         3.28            3  ...........      0.00884         0.05
99-09-2........................  Nitroaniline, 3-...............  ..........  ...........      0.02762         0.05  ..........         3.28            3  ...........      0.00884         0.05
100-01-6.......................  Nitroaniline, 4-...............  ..........  ...........      0.02762         0.02  ..........         3.28            1  ...........      0.00884         0.02
98-95-3........................  Nitrobenzene...................       0.345        0.084  ............      0.0064        44.8  ............      0.0544        0.032  ............      0.0064
55-86-7........................  Nitrogen mustard...............  ..........  ...........        0.159   ..........  ..........       19.955   ..........  ...........        0.105   ..........
51-75-2........................  Nitrogen mustard hydrochloride   ..........  ...........        0.159   ..........  ..........       19.955   ..........  ...........        0.105   ..........
                                  salt.                                                                                                                                                         
126-85-2.......................  Nitrogen mustard N-Oxide.......  ..........  ...........        0.159   ..........  ..........       19.955   ..........  ...........        0.105   ..........
302-70-5.......................  Nitrogen mustard N-Oxide, HCI    ..........  ...........        0.159   ..........  ..........       19.955   ..........  ...........        0.105   ..........
                                  salt.                                                                                                                                                         
55-63-0........................  Nitroglycerine.................  ..........  ...........        0.159   ..........  ..........       19.955   ..........  ...........        0.105   ..........
99-55-8........................  Nitro-o-toluidine, 5-..........  ..........  ...........      0.02762         0.01  ..........         3.28          0.7  ...........      0.00884         0.01
88-75-5........................  Nitrophenol, 2-................  ..........  ...........       0.0252         0.01  ..........        2.991          0.7  ...........       0.0083         0.01
100-02-7.......................  Nitrophenol, 4-................  ..........  ...........       0.0252         0.05  ..........        2.991            3  ...........       0.0083         0.05
79-46-9........................  Nitropropane, 2-...............     0.00019  ...........  ............     0.00577       0.128  ............      0.0022  ...........  ............     0.00577
56-57-5........................  Nitroquinoline-1-oxide, 4-.....  ..........  ...........        0.159         0.04  ..........       19.955            3  ...........        0.105         0.04
55-18-5........................  Nitrosodiethylamine............   0.0000406   3,1800E-06  ............       0.002     0.00064  ............           1    1.020E-06  ............     0.00262
62-75-9........................  Nitrosodimethylamine...........    0.000268    0.0000106  ............      0.0006     0.00245  ............       0.074    3.400E-06  ............      0.0006
924-16-3.......................  Nitrosodi-n-butylamine.........    0.000279     0.000122  ............        0.06       0.094  ............        0.03     0.000036  ............        0.06
10595-95-6.....................  Nitrosomethylethylamine........       0.129     0.000212  ............       0.028     0.00244  ............       0.016    6.800E-06  ............       0.028
1116-54-7......................  N-Nirtrosodiethanolamine.......  ..........  ...........    0.0000371         0.01  ..........     0.012875          0.7  ...........    0.0000119         0.01
621-64-7.......................  N-Nitrosodi-n-propylamine......      0.0644     0.000053  ............       0.026      0.0233  ............      0.0144     0.000017  ............       0.026
86-30-6........................  N-Nitrosodiphenylamine.........        7.54          0.2  ............        0.05        1270  ............      0.0846        0.046  ............        0.05
4549-40-0......................  N-Nitrosomethyl vinyl amine....  ..........  ...........    0.0000371   ..........  ..........     0.012875   ..........  ...........    0.0000119   ..........
59-89-2........................  N-Nitrosomorpholine............  ..........  ...........        0.159         0.05  ..........       19.955            3  ...........        0.105         0.05
759-73-9.......................  N-Nitroso-N-ethylurea..........  ..........  ...........        0.159   ..........  ..........       19.955   ..........  ...........        0.105   ..........
684-93-5.......................  N-Nitroso-N-methylurea.........  ..........  ...........        0.159         0.01  ..........       19.955          0.7  ...........        0.105         0.01
615-53-2.......................  N-Nitroso-N-methylurethane.....  ..........  ...........        0.159   ..........  ..........       19.955   ..........  ...........        0.105   ..........
16543-55-8.....................  N-Nitrosonornicotine...........  ..........  ...........        0.159   ..........  ..........       19.955   ..........  ...........        0.105   ..........
100-75-4.......................  N-Nitrosopiperidine............      0.0106    0.0000106  ............     0.00135     0.00247  ............       0.033    3.400E-06  ............     0.00135
930-55-2.......................  N-Nitrosopyrrolidine...........       0.101     0.000212  ............      0.0047      0.0534  ............       0.042     0.000068  ............      0.0047
13256-22-9.....................  N-Nitrososarcosine.............  ..........  ...........        0.159   ..........  ..........       19.955   ..........  ...........        0.105   ..........
103-85-5.......................  N-Phenylthiourea...............  ..........  ...........      0.11775   ..........  ..........         1.66   ..........  ...........          6.4   ..........
1615-80-1......................  N,N-Diethylhydrazine...........  ..........  ...........        0.159   ..........  ..........       19.955   ..........  ...........        0.105   ..........
152-16-9.......................  Octamethylpyrophosphoramide....        7310        0.273  ............      0.0053          31  ............       0.146        0.105  ............      0.0053
20816-12-0.....................  Osmium tetroxide...............  ..........  ...........        0.618            3  ..........         8.72          200  ...........        0.194            3
297-97-2.......................  O,O-Diethyl O-pyrazinyl          ..........  ...........       0.1175         0.02  ..........         1.66            1  ...........           64          002
                                  phosphorothioate.                                                                                                                                             
126-68-1.......................  O,O,O-Triethyl phosphorothioate  ..........  ...........      0.11775         0.05  ..........         1.66            3  ...........          6.4         0.05
123-63-7.......................  Paraldehyde....................  ..........  ...........          7.8            1  ..........         1210           70  ...........          6.2            1
56-38-2........................  Parathion......................        2.63       440000  ............      0.0005       0.128  ............       0.025        11600  ............      0.0005
608-93-5.......................  Pentachlorobenzene.............        7.86         5.15  ............    0.000038         205  ............        0.02       0.0543  ............    0.000038
76-01-7........................  Pentachloroethane..............  ..........  ...........       0.0241        0.005  ..........        30.85         0.01  ...........       0.0115        0.005
82-68-8........................  Pentachloronitrobenzene (PCNB).        13.9         0.27  ............        0.02        11.4  ............       0.052        0.018  ............        0.02
87-86-5........................  Pentachlorophenol..............       0.301      0.00204  ............     0.00008        2.92  ............      0.1222      0.00041  ............     0.00008
62-44-2........................  Phenacetin.....................  ..........  ...........         14.7         0.02  ..........         6900            1  ...........         10.5         0.02
85-01-8........................  Phenanthrene...................  ..........  ...........      0.00285        0.006  ..........          3.9          0.7  ...........      0.00119        0.006
108-95-2.......................  Phenol.........................       19300           84  ............     0.00028      163000  ............      0.2185           32  ............     0.00028
62-38-4........................  Phenyl mercuric acetate........       0.506       0.0117  ............  ..........     0.00932  ............  ..........       0.0045  ............  ..........

[[Page 66437]]
                                                                                                                                                                                                
25265-76-3.....................  Phenylenediamines (N.O.S.).....  ..........  ...........        0.159         0.01  ..........       19.955          0.7  ...........        0.105         0.01
108-45-2.......................  Phenylenediamine, m-...........        5440         0.78  ............      0.0174         784  ............         0.7          0.3  ............      0.0174
106-50-3.......................  Phenylenediamine, p-...........  ..........  ...........        0.159         0.01  ..........       19.955          0.7  ...........        0.105         0.01
298-02-2.......................  Phorate........................       0.106  ...........  ............     0.00004         157  ............       0.002  ...........  ............     0.00004
298-06-6.......................  Phosphorodithioic acid, o-o-     ..........  ...........      0.11775   ..........  ..........         1.66   ..........  ...........          6.4   ..........
                                  diethyl ester.                                                                                                                                                
3288-58-2......................  Phosphorodithioic acid, o-o-     ..........  ...........      0.11775   ..........  ..........         1.66   ..........  ...........          6.4   ..........
                                  diethyl-s-methyl.                                                                                                                                             
2953-29-9......................  Phosphorodithioic acid,          ..........  ...........      0.11775   ..........  ..........         1.66   ..........  ...........          6.4   ..........
                                  trimethyl ester.                                                                                                                                              
85-44-9........................  Phthalic anhydride.............  ..........  ...........          132   ..........  ..........       2352.5            7  ...........           42   ..........
109-06-8.......................  Picoline, 2-...................  ..........  ...........        0.159        0.001  ..........       19.955         0.07  ...........        0.105        0.001
1336-36-3......................  Polychlorinated biphenyls......    0.000286         11.5  ............      0.0005     0.00596  ............        0.04        0.009  ............      0.0005
23950-58-5.....................  Pronamide......................        80.3         21.3  ............     0.00145         438  ............       0.097          5.7  ............     0.00145
1120-71-4......................  Propane sultone, 1,3-..........  ..........  ...........      0.11775   ..........  ..........         1.66   ..........  ...........          6.4   ..........
107-10-8.......................  Propylamine, n-................  ..........  ...........        0.159        0.005  ..........       19.955        0.005  ...........        0.105        0.005
51-52-5........................  Propylthiouracil...............  ..........  ...........      0.11775          0.1  ..........         1.66            7  ...........          6.4          0.1
107-19-7.......................  Propyn-1-ol, 2-................  ..........  ...........           39         0.01  ..........        36700         0.05  ...........           15         0.01
129-00-0.......................  Pyrene.........................        3040         54.1  ............     0.00027       15800  ............      0.0726         1.69  ............     0.00027
110-86-1.......................  Pyridine.......................       0.522        0.156  ............       0.011         814  ............         0.2         0.06  ............       0.011
50-55-5........................  Reserpine......................  ..........  ...........        0.159         0.05  ..........       19.955            3  ...........        0.105         0.05
108-46-3.......................  Resorcinol.....................  ..........  ...........    0.0069415          0.1  ..........        0.194            7  ...........         0.54          0.1
81-07-2........................  Saccharin and salts............  ..........  ...........        0.159   ..........  ..........       19.955   ..........  ...........        0.105   ..........
94-59-7........................  Safrole........................      0.0829       0.0035  ............      0.0021        10.5  ............       0.015      0.00095  ............      0.0021
7782-49-2......................  Selenium.......................         822        0.232  ............      0.0006        1.94  ............           5       0.0892  ............      0.0006
7440-22-4......................  Silver.........................         199  ...........  ............      0.0005       1.134  ............         0.3  ...........  ............      0.0005
18883-66-4.....................  Streptozotocin.................  ..........  ...........         14.7   ..........  ..........         6900   ..........  ...........         10.5   ..........
57-24-9........................  Strychnine.....................        3.34        0.045  ............      0.0084      0.0041  ............           3        0.016  ............      0.0084
100-42-5.......................  Stryene........................        75.7         0.91  ............     0.00004      629000  ............       0.004         0.22  ............     0.00004
18496-25-8.....................  Sulfide........................  ..........  ...........            0            2  ..........            0            2  ...........            0            2
1746-01-6......................  TCDD, 2,3,7,8-.................   1.050E-09      0.00057  ............   1.000E-08    7.80E-06  ............   1.000E-06    5.400E-07  ............   1.000E-08
95-94-3........................  Tetrachlorobenzene, 1,2,4,5-...        14.8        0.234  ............     0.00141         168  ............       0.034       0.0317  ............     0.00141
630-20-6.......................  Tetrachloroethane, 1,1,1,2-....      0.0241        0.075  ............     0.00005         133  ............      0.0001       0.0078  ............     0.00005
79-34-5........................  Tetrachloroethane, 1,1,2,2-....      0.0037        0.024  ............      0.0002        29.3  ............      0.0002       0.0077  ............      0.0002
127-18-4.......................  Tetrachloroethylene............       15600       0.0255  ............     0.00014       13300  ............      0.0007       0.0085  ............     0.00014
58-90-2........................  Tetrachlorophenol, 2,3,4,6-....        2720         1.89  ............     0.00062        6150  ............        0.04         0.58  ............     0.00062
107-49-3.......................  Tetraethyl pyrophosphate.......  ..........  ...........         14.7   ..........  ..........         6900            3  ...........         10.5   ..........
3689-24-5......................  Tetraethyldithiopyrophosphate..        0.23  ...........  ............    0.000058        2.81  ............      0.0039  ...........  ............    0.000058
7440-28-0......................  Thallium (l)...................         646       0.0353  ............      0.0007        5.12  ............           3        0.014  ............      0.0007
62-55-5........................  Thioacetamide..................  ..........  ...........        0.159            1  ..........       19.955   ..........  ...........        0.105            1
39196-18-4.....................  Thiofanox......................  ..........  ...........      0.11775         0.05  ..........         1.66            3  ...........          6.4         0.05
108-98-5.......................  Thiophenol.....................  ..........  ...........      0.11775         0.02  ..........         1.66            1  ...........          6.4         0.02
79-19-6........................  Thiosemicarbazide..............  ..........  ...........      0.11775   ..........  ..........         1.66   ..........  ...........          6.4   ..........
62-56-6........................  Thiourea.......................  ..........  ...........      0.11775   ..........  ..........         1.66   ..........  ...........          6.4   ..........
137-26-8.......................  Thiram.........................  ..........  ...........    0.0069415         0.05  ..........        0.194            3  ...........         0.54         0.05
7440-31-5......................  Tin............................  ..........  ...........        0.618            8  ..........         8.72          500  ...........        0.194            8
108-88-3.......................  Toluene........................        29.8          5.9  ............     0.00011      176000  ............      0.0002          1.8  ............     0.00011
584-84-9.......................  Toluene diisocyanate...........  ..........  ...........        0.159   ..........  ..........       19.955            7  ...........        0.105   ..........
95-80-7........................  Toluenediamine, 2,4-...........       0.211     0.000159  ............      0.0134      0.0101  ............           1     0.000051  ............      0.0134
823-40-5.......................  Toluenediamine, 2,6-...........  ..........  ...........        0.159         0.02  ..........       19.955            1  ...........        0.105         0.02
496-72-0.......................  Toluenediamine, 3,4-...........  ..........  ...........        0.159         0.02  ..........       19.955            1  ...........        0.105         0.02
636-21-5.......................  Toluidine hydrochloride, o-....  ..........  ...........        0.159         0.01  ..........       19.955          0.7  ...........        0.105         0.01
95-53-4........................  Toluidine, o-..................       0.441      0.00224  ............      0.0121        2.35  ............       0.029      0.00068  ............      0.0121
106-49-0.......................  Toluidine, p-..................       0.703      0.00224  ............      0.0168       0.128  ............       0.043      0.00068  ............      0.0168
8001-35-2......................  Toxaphene......................    0.000364         1170  ............     0.00127    0.000176  ............      0.0295          6.3  ............     0.00127
76-13-1........................  Trichloro-1,2,2-                       2210         0.77  ............     0.00108  ..........  ............     0.00114        0.168  ............     0.00108
                                  trifluoroethane, 1,1,2-.                                                                                                                                      
120-82-1.......................  Trichlorobenzene, 1,2,4-.......       0.685         9.31  ............      0.0002        3450  ............      0.0574          1.3  ............      0.0002
71-55-6........................  Trichloroethane, 1,1,1-........        73.9          120  ............     0.00008       48200  ............      0.0002       0.0539  ............     0.00008
79-00-5........................  Trichloroethane, 1,1,2-........      0.0117        0.035  ............      0.0001        11.3  ............       0.004        0.009  ............      0.0001
79-01-6........................  Trichloroethylene..............         138        0.024  ............     0.00019         567  ............      0.0001        0.008  ............     0.00019
75-69-4........................  Trichlorofluoromethane.........        51.4           48  ............     0.00008       25800  ............       0.001           16  ............     0.00008
75-70-7........................  Trichloromethanethiol..........  ..........  ...........      0.11775   ..........  ..........         1.66   ..........  ...........          6.4   ..........
95-95-4........................  Trichlorophenol, 2,4,5-........        38.8         18.1  ............     0.00049       11500  ............      0.0672          4.2  ............     0.00049
88-06-2........................  Trichlorophenol, 2,4,6-........         0.1       0.0536  ............      0.0004         124  ............      0.0785       0.0152  ............      0.0004
93-76-5........................  Trichlorophenoxyacetic acid,           15.5         1.68  ............     0.00008        63.2  ............      0.0063         0.64  ............     0.00008
                                  2,4,5- (245-T).                                                                                                                                               
93-72-1........................  Trichlorophenoxypropionic acid,        9.72         0.21  ............     0.00008        6.36  ............     0.00028         0.08  ............     0.00008
                                  2,4,5- (Silvex).                                                                                                                                              
96-18-4........................  Trichloropropane, 1,2,3-.......         707          1.1  ............     0.00032         872  ............      0.0009         0.34  ............     0.00032
99-35-4........................  Trinitrobenzene, sym-..........           3       0.0078  ............     0.00026       0.442  ............        0.25        0.003  ............     0.00026
126-72-7.......................  Tris (2,3-dibromopropyl)           0.000237      0.00252  ............      0.0245       0.357  ............       0.061     0.000099  ............      0.0245
                                  phosphate.                                                                                                                                                    

[[Page 66438]]
                                                                                                                                                                                                
52-24-4........................  Tris(1-azridinyl) phosphine      ..........  ...........      0.11775   ..........  ..........         1.66   ..........  ...........          6.4   ..........
                                  sulfide.                                                                                                                                                      
72-57-1........................  Trypan blue....................  ..........  ...........         14.7   ..........  ..........         6900   ..........  ...........         10.5   ..........
66-75-1........................  Uracil mustard.................  ..........  ...........        0.159   ..........  ..........       19.955   ..........  ...........        0.105   ..........
7440-62-2......................  Vanadium.......................       15800         9.58  ............       0.003         250  ............           1         3.71  ............       0.003
108-05-4.......................  Vinyl acetate..................  ..........  ...........         14.7        0.005  ..........         6900        0.005  ...........         10.5        0.005
75-01-4........................  Vinyl chloride.................     0.00199       0.0078  ............     0.00017        1.23  ............      0.0017        0.003  ............     0.00017
81-81-2........................  Warfarin.......................  ..........  ...........    0.0069415         0.05  ..........        0.194            3  ...........         0.54         0.05
1330-20-7......................  Xylenes (total)................        22.4           88  ............       0.002      172000  ............      0.0002           21  ............       0.002
7440-66-6......................  Zinc...........................       23200           99  ............       0.002         316  ............         0.3         38.4  ............       0.002
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------



Appendix D

                                  Table D-1.--Comparison Between Modeled Exit Levels and Universal Treatment Standards                                  
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                   Wastewater                            Nonwastewater                  
                                                                           -----------------------------------------------------------------------------
                  CAS                                  Name                  Exit level                Exit level   UTS  (mg/    Exit level             
                                                                               (mg/l)    UTS  (mg/l)    (mg/kg)        kg)         (mg/l)    UTS  (mg/l)
--------------------------------------------------------------------------------------------------------------------------------------------------------
83-32-9...............................  Acenaphthene......................           31        0.059         9500          3.4            5  ...........
67-64-1...............................  Acetone...........................           16         0.28        17000          160            6  ...........
75-05-8...............................  Acetonitrile......................         0.78          5.6          920         *1.8          0.3  ...........
98-86-2...............................  Acetophenone......................           17         0.01         1200          9.7            6  ...........
107-02-8..............................  Acrolein..........................    eqc               0.29  ...........  ...........  ...........  ...........
107-13-1..............................  Acrylonitrile.....................    eqc               0.24         0.96           84    eqc        ...........
107-05-1..............................  Allyl chloride....................        0.074         0.36          260           30  ...........  ...........
62-53-3...............................  Aniline...........................        0.053         0.81            4           14        0.017  ...........
7440-36-0.............................  Antimony..........................         0.14          1.9            9  ...........        0.053          2.1
7440-38-2.............................  Arsenic...........................    eqc                1.4    eqc        ...........    eqc                  5
7440-39-3.............................  Barium............................           33          1.2         2100  ...........           16          7.6
56-55-3...............................  Benz(a)anthracene.................      0.00072        0.059          0.1          3.4    eqc        ...........
71-43-2...............................  Benzene...........................        0.018         0.14          110           10       0.0054  ...........
50-32-8...............................  Benzo(a)pyrene....................       0.0023        0.061         0.23          3.4    eqc        ...........
205-99-2..............................  Benzo(b)fluoranthene..............      0.00081         0.11            4          6.8     0.000066  ...........
7440-41-7.............................  Beryllium.........................      0.00083         0.82    eqc        ...........      0.00032        0.014
39638-32-9............................  Bis (2-chloroisopropyl) ether.....        0.007        0.055         0.94          7.2       0.0019  ...........
111-44-4..............................  Bis(2-chlorethyl)ether............      0.00065        0.033         0.12            6      0.00036  ...........
117-81-7..............................  Bis(2-ethylhexyl)phthalate........      0.00044         0.28          230           28       0.0011  ...........
75-27-4...............................  Bromodichloromethane..............       0.0085         0.35           19           15       0.0025  ...........
75-25-2...............................  Bromoform (Tribromomethane).......        0.064         0.63          170           15        0.018  ...........
71-36-3...............................  Butanol...........................           16          5.6        18000          2.6            6  ...........
88-85-7...............................  Butyl-4,6-dinitrophenol, 2-sec-            0.19        0.066          770          2.5        0.064  ...........
                                         (Dinoseb).                                                                                                     
85-68-7...............................  Butylbenzylphthalate..............          240        0.017           87           28           64  ...........
7440-43-9.............................  Cadmium...........................         0.24         0.69           14  ...........         0.11         0.19
75-15-0...............................  Carbon disulfide..................         0.74          3.8          330  ...........            6          4.8
56-23-5...............................  Carbon tetrachloride..............        0.012        0.057            9            6       0.0016  ...........
57-74-9...............................  Chlordane.........................    eqc             0.0033       0.0098         0.26      0.00016  ...........
126-99-8..............................  Chloro-1,3-butadiene, 2-                   0.52        0.057          290         0.28  ...........  ...........
                                         (Chloroprene).                                                                                                 
106-47-8..............................  Chloroaniline, p-.................         0.42         0.46          140           16         0.16  ...........
108-90-7..............................  Chlorobenzene.....................            2        0.057         2500            6            1  ...........
510-15-6..............................  Chlorobenzilate...................        0.054          0.1  ...........  ...........  ...........  ...........
124-48-1..............................  Chlorodibromomethane..............       0.0066        0.057           28           15       0.0018  ...........
67-66-3...............................  Chloroform........................       0.0076        0.046            7            6        0.017  ...........
95-57-8...............................  Chlorophenol, 2-..................          0.9        0.044          100          5.7         0.32  ...........
7440-47-3.............................  Chromium..........................            1         2.77           10  ...........         0.48         0.86
218-01-9..............................  Chrysene..........................          0.1        0.059           35          3.4       0.0012  ...........
108-39-4..............................  Cresol, m-........................            8         0.77        22000          5.6            3  ...........
95-48-7...............................  Cresol, o-........................            8         0.11        27000          5.6            3  ...........
106-44-5..............................  Cresol, p-........................         0.84         0.77         2600          5.6         0.32  ...........
72-54-8...............................  DDD...............................      0.00013        0.023       0.0065        0.087         2800  ...........
72-55-9...............................  DDE...............................    eqc              0.031      0.00094        0.087     0.000062  ...........
50-29-3...............................  DDT...............................    eqc             0.0039       0.0032        0.087       0.0054  ...........
84-74-2...............................  Di-n-butyl phthalate..............          230        0.057        90000           28           25  ...........
117-84-0..............................  Di-n-octyl phthalate..............        0.002        0.017         4500           28          0.1  ...........
96-12-8...............................  Dibromo-3-choloropropane, 1,2-....      0.00066         0.11         0.66           15    eqc        ...........
95-50-1...............................  Dichlorobenzene, 1,2-.............           15        0.088        50000            6            6  ...........
106-46-7..............................  Dichlorobenzene, 1,4-.............        0.056         0.09           64            6        0.011  ...........
75-71-8...............................  Dichlorodifluoromethane...........           15         0.23         8100          7.2           12  ...........
75-34-3...............................  Dichloroethane, 1,1-..............      0.00016        0.059           24            6      0.00006  ...........
107-06-2..............................  Dichloroethane, 1,2-..............      0.00016         0.21            6            6      0.00006  ...........
75-35-4...............................  Dichloroethylene, 1,1-............      0.00059        0.025            3            6      0.00018  ...........
156-60-5..............................  Dichloroethylene, trans-1,2-......            3        0.054        14000           30            1  ...........
120-83-2..............................  Dichlorophenol, 2,4-..............         0.62        0.044          770           14         0.18  ...........

[[Page 66439]]
                                                                                                                                                        
94-75-7...............................  Dichlorophenoxyacetic acid, 2,4-              2         0.72         3100           10          0.6  ...........
                                         (2,4-D).                                                                                                       
78-87-5...............................  Dichloropropane, 1,2-.............        0.023         0.85           17           18       0.0023  ...........
10061-01-5............................  Dichloropropene, cis-1,3-.........       0.0049        0.036            3           18         1200  ...........
10061-02-6............................  Dichloropropene, trans-1,3-.......       0.0049        0.036            3           18         1200  ...........
60-57-1...............................  Dieldrin..........................     0.000059        0.017       0.0018         0.13         0.54  ...........
84-66-2...............................  Diethyl phthalate.................          190          0.2         4500           28           54  ...........
131-11-3..............................  Dimethyl phthalate................           78        0.047            3           28           30  ...........
105-67-9..............................  Dimethylphenol,2,4-...............            4        0.036        11000           14            1  ...........
51-28-5...............................  Dinitrophenol,2,4-................         0.27         0.12           56          160         0.11  ...........
121-14-2..............................  Dinitrotoluene,2,4-...............         0.29         0.32          210          140         0.11  ...........
606-20-2..............................  Dinitrotoluene,2,6-...............         0.17         0.55           86           28        0.064  ...........
123-91-1..............................  Dioxane,1,4-......................        0.042          *NA           13          170        0.014  ...........
122-39-4..............................  Diphenylamine.....................           15         0.92        12000           13            3  ...........
298-04-4..............................  Disulfoton........................        0.013        0.017           43          6.2           13  ...........
72-20-8...............................  Enndrin...........................        0.073       0.0028         0.26         0.13           32  ...........
141-78-6..............................  Ethyl acetate.....................          390         0.34       270000           33          110  ...........
60-29-7...............................  Ethyl ether.......................           27         0.12        41000          160           11  ...........
97-63-2...............................  Ethyl methacrylate................           24         0.14         3400          160            7  ...........
100-41-4..............................  Ethylbenzene......................           39        0.057       550000           10            8  ...........
206-44-0..............................  Flouranthene......................           28        0.068         6000          3.4            2  ...........
86-73-7...............................  Flourene..........................           22        0.059        90000          3.4            3  ...........
76-44-8-..............................  Heptachlor........................    eqc             0.0012            8        0.066  ...........  ...........
1024-57-3.............................  Heptachlor epoxide................      0.00053        0.016        0.026        0.066         0.45  ...........
87-68-3...............................  Hexachloro-1,3-butadiene..........       0.0079        0.055           36          5.6       0.0069  ...........
118-74-1..............................  Hexachlorobenzene.................    eqc              0.055    eqc                 10    eqc        ...........
319-84-6..............................  Hexachlorocyclohexane, alpha-           0.00014      0.00014        0.033        0.066         0.11  ...........
                                         (alpha-BHC).                                                                                                   
319-85-7..............................  Hexachlorocyclohexane, beta-(beta-      0.00044      0.00014         0.12        0.066      0.00021  ...........
                                         BHC).                                                                                                          
58-89-9...............................  Hexachlorocyclohexane, gamma-           0.00078       0.0017          0.1        0.066         0.69  ...........
                                         (Lindane).                                                                                                     
77-47-4...............................  Hexachlorocyclopentadiene.........       0.0052        0.057         1500          2.4  ...........  ...........
67-72-1...............................  Hexachloroethane..................        0.049        0.055           81           30        0.033  ...........
193-39-5..............................  Indeno(1,2,3-cd) pyrene...........       0.0029       0.0055            4          3.4    eqc        ...........
78-83-1...............................  Isobutyl alcohol..................           39          5.6        55000          170           15  ...........
7439-92-1.............................  Lead..............................           30         0.69          570  ...........           12         0.37
7439-97-6.............................  Mercury...........................          0.3         0.15          0.6  ...........         0.14        0.025
126-98-7..............................  Methacrylonitrile.................        0.016         0.24  ...........  ...........  ...........  ...........
67-56-1...............................  Methanol..........................           78          5.6       140000  ...........           30         0.75
72-43-5...............................  Methoxychlor......................            7         0.25           19         0.18  ...........  ...........
74-83-9...............................  Methyl bromide (Bromomethane).....         0.37         0.11          500           15         0.92  ...........
74-87-3...............................  Methyl chloride (Chloromethane)...        0.096         0.19           91           30  ...........  ...........
78-93-3...............................  Methyl ethyl ketone...............           78         0.28       110000           36           30  ...........
108-10-1..............................  Methyl isobutyl ketone............            8         0.14        17000           33            3  ...........
80-62-6...............................  Methyl methacrylate...............           28         0.14        40000          160            8  ...........
298-00-0..............................  Methyl parathion..................         0.66        0.014            1          4.6           23  ...........
74-95-3...............................  Methylene bromide.................            2         0.11         8400           15         0.19  ...........
75-09-2...............................  Methylene chloride................        0.039        0.089          310           30        0.015  ...........
86-30-6...............................  N-Nitrosodiphenylamine............          0.2         0.92         1300           13    eqc        ...........
930-55-2..............................  N-Nitrosopyrrolidine..............    eqc              0.013        0.053           35    eqc        ...........
91-20-3...............................  Naphthalene.......................           14        0.059       120000          5.6            3  ...........
7440-02-0.............................  Nickel............................           11         3.98          110  ...........            5            5
98-95-3...............................  Nitrobenzene......................        0.084        0.068           45           14        0.032  ...........
924-16-3..............................  Nitrosodi-n-butylamine............  ...........  ...........        0.094           17    eqc        ...........
56-38-2...............................  Parathion.........................            3        0.014         0.13          4.6        12000  ...........
608-93-5..............................  Pentachlorobenzene................            5        0.055          210           10    eqc        ...........
82-68-8...............................  Pentachloronitrobenzene (PCNB)....        0.081        0.055           11          4.8    eqc        ...........
87-86-5...............................  Pentachlorophenol.................        0.002        0.089            3          7.4      0.00041  ...........
108-95-2..............................  Phenol............................           84        0.039       160000          6.2           32  ...........
298-02-2..............................  Phorate...........................         0.11        0.021          160          4.6  ...........  ...........
1336-36-3.............................  Polychlorinated biphenyls.........    eqc                0.1    eqc                 10    eqc        ...........
23950-58-5............................  Pronamide.........................           21        0.093          440          1.5            6  ...........
129-00-0..............................  Pyrene............................           54        0.067        16000          8.2            2  ...........
110-86-1..............................  Pyridine..........................         0.16        0.014          810           16         0.06  ...........
94-59-7...............................  Safrole...........................       0.0035        0.081           11         0.16    eqc        ...........
7782-49-2.............................  Selenium..........................         0.93         0.82    eqc        ...........         0.36         0.16
7440-22-4.............................  Silver............................          200         0.43    eqc        ...........  ...........          0.3
1746-01-6.............................  TCDD,2,3,7,8......................    eqc           0.000063    8.000E-06        0.001    eqc        ...........
95-94-3...............................  Tetrachlorobenzene, 1,2,4,5-......         0.23        0.055          170           14        0.032  ...........
630-20-6..............................  Tetrachloroethane, 1,1,1,2-.......        0.024        0.057          130            6       0.0078  ...........
79-34-5...............................  Tetrachloroethane, 1,1,2,2-.......       0.0037        0.057           29            6       0.0077  ...........
127-18-4..............................  Tetrachloroethylene...............            2        0.056        13000            6         0.68  ...........
58-90-2...............................  Tetrachlorophenol, 2,3,4,6-.......            2         0.03         6200          7.4         0.58  ...........
7440-28-0.............................  Thallium (l)......................         0.05          1.4            5        0.078        0.019  ...........
108-88-3..............................  Toluene...........................           30         0.08       180000           10           13  ...........
8001-35-2.............................  Toxaphene.........................    eqc             0.0095    eqc                2.6         0.11  ...........
76-13-1...............................  Trichloro-1,2,2-trifluoroethane,           2200        0.057  ...........           30         2400  ...........
                                         1,1,2-.                                                                                                        
120-82-1..............................  Trichlorobenzene, 1,2,4-..........         0.69        0.055         3500           19            1  ...........
71-55-6...............................  Trichloroethane, 1,1,1-...........           74        0.054        48000            6        0.054  ...........
79-00-5...............................  Trichloroethane, 1,1,2-...........        0.007        0.054           11            6       0.0018  ...........
79-01-6...............................  Trichloroethylene.................        0.038        0.054          570            6        0.013  ...........
75-69-4...............................  Trichlorofluoromethane............           48         0.02        26000           30           16  ...........

[[Page 66440]]
                                                                                                                                                        
95-95-4...............................  Trichlorophenol, 2,4,5-...........           18         0.18        12000          7.4            4  ...........
88-06-2...............................  Trichlorophenol, 2,4,6-...........        0.054        0.035          120          7.4        0.015  ...........
93-76-5...............................  Trichlorophenoxyacetic acid, 2,4,5-           2         0.72           63          7.9         0.64  ...........
                                          (245-T).                                                                                                      
93-72-1...............................  Trichlorophenoxypropionic acid,               1         0.72            6          7.9         0.48  ...........
                                         2,4,5- (Silvex).                                                                                               
96-18-4...............................  Trichloropropane, 1,2,3-..........            1         0.85          870           30         0.34  ...........
126-72-7..............................  Tris (2,3-dibromopropyl) phosphate    eqc               0.11         0.36          0.1    eqc        ...........
7440-62-2.............................  Vanadium..........................           10          4.3          250  ...........            4         0.23
75-01-4...............................  Vinyl chloride....................    eqc               0.27            1            6    eqc        ...........
1330-20-7.............................  Xylenes (total....................           22         0.32       170000           30          150  ...........
7440-66-6.............................  Zinc..............................           99         2.61          320  ...........           38          5.3
--------------------------------------------------------------------------------------------------------------------------------------------------------


    For the reasons set out in the preamble, Chapter I of Title 40 of 
the Code of Federal Regulations is amended as follows:

PART 260--HAZARDOUS WASTE MANAGEMENT SYSTEM: GENERAL

    1. The authority citation for part 260 continues to read as 
follows:

    Authority: 42 U.S.C. 6905, 6912(a), 6921-6927, 6930, 6934, 6935, 
6937, 6938, 6939, and 6974.

    2. In Sec. 260.10, add the following definitions in alphabetical 
order:
* * * * *
    Director means the Regional Administrator or the State Director, as 
the context requires, or an authorized representative. When there is no 
approved State program, and there is an EPA administered program, 
Director means the Regional Administrator. When there is an approved 
State program, Director normally means the State Director. In some 
circumstances, however, EPA retains the authority to take certain 
actions even when there is an approved State program. In such cases, 
the term Director means the Regional Administrator and not the State 
Director.
* * * * *
    Monofill means a landfill where waste of only one kind or type is 
placed in or on land and which is not a pile, a land treatment 
facility, a surface impoundment, an underground injection well, a salt 
dome formation, a salt bed formation, an underground mine, a cave, or a 
corrective action management unit.

PART 261--IDENTIFICATION AND LISTING OF HAZARDOUS WASTE

    3. The authority citation for part 261 continues to read as 
follows:

    Authority: 42 U.S.C. 6905, 6912(a), 6921, and 6922.

    4. Section 261.3 is amended by revising the first sentence of 
paragraph (a)(2)(iv) and the first sentence of paragraph (c)(2)(i) to 
read as follows:


Sec. 261.3  Definition of hazardous waste.

* * * * *
    (a) * * *
    (2) * * *
    (iv) It is a mixture of solid waste and one or more hazardous 
wastes listed in subpart D of this part and has not been excluded from 
paragraph (a)(2) of this section under either Secs. 260.20 and 260.22, 
Sec. 261.36, or Sec. 261.37 of this chapter; however, the following 
mixtures of solid wastes and hazardous wastes listed in subpart D of 
this part are not hazardous wastes (except by application of paragraph 
(a)(2) (i) or (ii) of this section) if the generator can demonstrate 
that the mixture consists of wastewater the discharge of which is 
subject to regulation under either section 402 or section 307(b) of the 
clean water act (including wastewater at facilities which have 
eliminated the discharge of wastewater) and:
* * * * *
    (c) * * *
    (2) * * *
    (i) Except as otherwise provided in paragraph (c)(2)(ii) of this 
section, Sec. 261.36, or Sec. 261.37 of this chapter, any solid waste 
generated from the treatment, storage, or disposal of a hazardous 
waste, including any sludge, spill residue, ash, emission control dust, 
or leachate (but not including precipitation run-off) is a hazardous 
waste. * * *
* * * * *
    5. A new Sec. 261.36 is added to subpart D to read as follows:


Sec. 261.36  Exemption for listed hazardous wastes containing low 
concentrations of hazardous constituents.

    (a) Any hazardous waste listed under this subpart, any mixture of 
such a listed waste with a solid waste, or any waste derived from the 
treatment, storage, or disposal of a listed hazardous waste that does 
not exhibit any of the characteristics of hazardous waste in subpart C 
of this part 261 and that meets all of the requirements in 
Sec. 261.36(b)-(d) is exempt from all requirements of parts 262-266 and 
part 270 of this chapter. Any such waste which also meets the 
requirements of Sec. 261.36(e) is also exempt from the requirements of 
part 268 of this chapter.
    (b) Requirements for qualifying for an exemption.--(1) Testing. (i) 
For each waste for which an exemption is claimed, the claimant must 
test for all of the constituents on appendix X to this part 261 except 
those that the claimant determines should not be present in the waste. 
The claimant is required to document the basis of each determination 
that a constituent should not be present. No claimant may determine 
that any of the following categories of constituents should not be 
present:
    (A) Constituents identified in appendix VII to this part 261 as the 
basis for listing the waste for which exemption is sought;
    (B) Constituents listed in the table to Sec.  268.40 of this 
chapter as regulated hazardous constituents for LDR treatment of the 
waste;
    (C) Constituents detected in any previous analysis of the same 
waste conducted by or on behalf of the claimant;
    (D) Constituents introduced into the process which generates the 
waste; and
    (E) Constituents which the claimant knows or has reason to believe 
are byproducts or side reactions to the process that generates the 
waste.

    Note: Any claim under this section must be valid and accurate 
for all hazardous constituents; a determination not to test for a 
hazardous constituent will not shield a claimant from liability 
should that constituent later be found in the waste.

    (ii) The claimant must develop a sampling and analysis plan for 
each waste for which an exemption is sought. The plan must identify:
    (A) Sampling procedures and locations sufficient to characterize 
the entire waste for which the exemption is 

[[Page 66441]]
claimed. Grab sampling is acceptable for this purpose.
    (B) Analytical methods that the claimant will use to determine, for 
wastewaters and nonwastewaters, the total concentration of each 
constituent on appendix X to this part except for those constituents 
which the claimant has determined should not be present under 
Sec. 261.36(b)(1)(i).
    (iii) The claimant must conduct sampling and analysis in accordance 
with the plan.
    (iv) The results of the sampling and analysis must show, for both 
wastewaters and nonwastewaters, that all total constituent 
concentrations in the waste are at or below the exemption levels in 
appendix X to this part 261 and, for nonwastewaters, that all leachable 
constituent concentrations are either:
    (A) At or below exemption levels in Appendix X to this part 261, as 
determined by testing an extract using test method 1311 (the Toxicity 
Characteristic Leaching Procedure, set out in ``Test Methods for 
Evaluating Solid Waste, Physical/Chemical Methods'' (SW-846)), or
    (B) Estimated to be at or below exemption levels using the equation 
{[(A x B)+(C x D)]/[B+(20 x D)]} leach exit level, where 
A=concentration of the analyte in the liquid portion of the sample; 
B=Volume of the liquid portion of the sample; C=Concentration of the 
analyte in the solid portion of the sample; D=Weight of the solid 
portion of the sample.
    (2) Treatment requirements.  Any waste that exits using an exit 
level on Table B to appendix X to this part 261 must meet the treatment 
standard for such a constituent under Sec. 268.40 of this chapter, 
regardless of whether or not the waste is intended for land disposal, 
unless the claimant meets the exemption requirements in Sec. 261.36(e).
    (3) Public Notice. The claimant must submit for publication in a 
major newspaper of general circulation, local to the claimant, a notice 
entitled ``Notification of Exemption Claim for Listed Hazardous Wastes 
Containing Low Concentrations of Hazardous Constituents Under the 
Resource Conservation and Recovery Act'' containing the following 
information:
    (i) The name, address, and RCRA ID number of the claimant's 
facility;
    (ii) The applicable EPA Hazardous Waste Code of the waste for which 
the exemption is claimed and the narrative description associated with 
the listing from this part 261 subpart D;
    (iii) A brief, general description of the manufacturing, treatment, 
or other process or operation producing the waste;
    (iv) An estimate of the average and maximum monthly and annual 
quantities of the waste claimed to be exempt;
    (v) The name and mailing address of the agency to which the 
claimant is submitting the notification required under 
Sec. 261.36(b)(4).
    (4) Notification to implementing agency. Prior to managing any 
waste as exempt under this section, the claimant must send to the 
Director via certified mail or other mail service that provides written 
confirmation of delivery a notification of the exemption claim meeting 
the following requirements:
    (i) The name, address, and RCRA ID number of the person claiming 
the exemption;
    (ii) The applicable EPA Hazardous Waste Codes;
    (iii) A brief description of the process that generated the waste;
    (iv) An estimate of the average and maximum monthly and annual 
quantities of each waste claimed to be exempt;
    (v) Documentation for any claim that a constituent is not present 
as described under Sec. 261.36 (b)(1)(i);
    (vi) The results of all analyses and estimates of constituent 
concentrations required under Sec. 261.36(b)(1)(iv) and all 
quantitation limits achieved;
    (vii) Documentation that any waste that exits using a constituent 
exit level from Table B to Appendix X to this part has met the 
applicable treatment standards in Sec. 268.40 of this chapter, unless 
the claimant is also claiming the exemption under Sec. 261.36(e);
    (viii) Evidence that the public notification requirements of 
Sec. 261.36(b)(3) have been satisfied; and
    (ix) The following statement signed by the person claiming the 
exemption or his authorized representative:

    ``Under penalty of criminal and civil prosecution for making or 
submitting false statements, representations, or omissions, I 
certify that the requirements of 40 CFR 261.36(b) have been met for 
all waste identified in this notification. Copies of the records and 
information required at 40 CFR 261.36(d)(7) are available at the 
claimant's facility. Based upon my inquiry of the individuals 
immediately responsible for obtaining the information, the 
information is, to the best of my knowledge and belief, true, 
accurate, and complete. I am aware that there are significant 
penalties for submitting false information, including the 
possibility of fine and imprisonment for knowing violations.''

    (c) Effectiveness of exemption. No claim shall take effect until 
the claimant receives confirmation of delivery for the notification 
required under Sec. 261.36 (b)(4).
    (d) Conditions for maintaining the exemption. To maintain any 
exemption claimed pursuant to this section, the claimant must satisfy 
the following conditions:
    (1) Changes in information. The claimant must submit to the 
Director any change in any information submitted under 
Sec. 261.36(b)(4) within ten business days of the claimant's first 
knowledge of the change.
    (2) Schedule for retesting. The claimant must retest the waste for 
which the exemption was claimed on the following schedule:
    (i) For the first three years of the exemption, the claimant must:
    (A) Test wastes generated at the time the exemption is claimed in 
volumes greater than 10,000 tons/year on a quarterly basis;
    (B) Test wastes generated at the time the exemption is claimed in 
volumes greater than 1000 tons/year but less than 10,000 tons/year must 
on a semi-annual basis;
    (C) Test wastes generated at the time the volume is claimed in 
volumes less than 1000 tons/year on an annual basis.
    (ii) After the first three years of an exemption, the claimant must 
retest the waste for which the exemption was claimed on an annual 
basis.
    (3) For every retest the claimant must prepare and comply with a 
sampling and analysis plan meeting the requirements of 
Sec. 261.36(b)(1)(ii) and determine the concentration of:
    (i) Each constituent from Table A to appendix X to this part that 
was detected in the initial test within an order of magnitude below 
either its total or leachable exemption level and each constituent from 
Table B to appendix X of this part that is identified as a basis for 
listing the waste on appendix VII to this part or is listed as a 
regulated hazardous constituent for the waste in the table of 
``Treatment Standards for Hazardous Wastes'' in Sec. 268.40 of this 
chapter; and
    (ii) Any other constituent that the claimant has reason to believe 
may be newly present in the waste since the most recent test.
    (4) Exemption levels. The concentrations of all constituents tested 
must meet the criteria set out in Sec. 261.36(b)(1)(iv).
    (5) Treatment requirements. Any waste exiting by using an exit 
level for a hazardous constituent from Table B to appendix X to this 
part must meet the treatment requirements for such a constituent under 
Sec. 268.40 of this chapter prior to exit regardless of whether or not 
the waste is intended for land disposal, unless the claimant meets 

[[Page 66442]]
the exemption requirements in Sec. 261.36(e).
    (6) Records. The claimant must maintain records of the following 
information in files on-site for three years after the date of the 
relevant test:
    (i) For initial testing, all information submitted under 
Sec. 261.36(b)(4), all revisions to such material submitted under 
Sec. 261.36(d)(1) and all information required to be maintained under 
Sec. 261.36(d)(6)(iii);
    (ii) For retests:
    (A) All volume determinations made for the purpose of determining 
testing frequency under Sec. 261.36(d)(2);
    (B) All sampling and analysis plans required under 
Sec. 261.36(d)(3);
    (C) All analytical results and estimates of leachable 
concentrations (if any) for constituents required to be assessed under 
Sec. 261.35(d)(3);
    (D) Documentation showing that a waste exiting using any 
constituent exit level from Table B to appendix X to this part and is 
required to be reassessed under Sec. 261.36(d)(3) has met applicable 
treatment standards under Sec. 268.40 of this chapter, unless the 
claimant also claims the exemption under Sec. 261.36(e); and
    (iii) For both initial tests and retests, the claimant must also 
retain records of:
    (A) The dates and times waste samples were obtained, and, for total 
concentrations and leachable concentrations that were analyzed, the 
dates of the analyses;
    (B) The names and qualifications of the person(s) who obtained the 
samples;
    (C) A description of the temporal and spatial locations of the 
samples;
    (D) The name and address of the laboratory facility at which 
analyses of the samples were performed;
    (E) A description of the analytical methods used, including any 
clean-up and extraction methods;
    (F) All quantitation limits achieved and all other quality control 
results (including any method blanks, duplicate analyses, and matrix 
spikes), laboratory quality assurance data, and a description of any 
deviations from published analytical methods or from the plan which 
occurred; and
    (G) All laboratory documentation that supports the analytical 
results, unless a contract between the claimant and the laboratory 
provides for the documentation to be maintained by the laboratory for 
the period specified in Sec. 261.36 (b)(2) and also provides for the 
availability of the documentation to the claimant upon request.

    Note: Failure to satisfy any of these conditions voids the 
exemption and requires management of the waste for which the 
exemption has been claimed as hazardous waste. Submission of 
notification to the Director that all waste conditions have been 
satisfied re-establishes the exemption for all waste generated after 
that date.

    (e) Exemption from part 268 requirements.--If all hazardous 
constituent levels in a waste qualifying for exemption are at or below 
the appendix X to this part concentration levels at the waste's point 
of generation, prior to any mixing with other solid or hazardous wastes 
and prior to any treatment, the waste is exempt from all requirements 
of part 268 of this chapter. The claimant also must meet the following 
documentation requirements:
    (1) For initial tests, in place of the certification required at 
Sec. 261.36 (b)(4)(ix), the claimant must submit the following 
statement signed by the person claiming the exemption or his authorized 
representative and, if the claimant is not the generator of the waste, 
also signed by the generator or his authorized representative:

    Under penalty of criminal and civil prosecution for making or 
submitting false statements, representations, or omissions, I 
certify that, for the waste identified in this notification, the 
concentration of all constituents assessed as required under 
Sec. 261.36 (b)(1)(iv) met the applicable levels in appendix X to 
this part 261 at the point of generation and that all other 
requirements of 40 CFR Sec. 261.36 (b) have been met. Copies of the 
records and information required at 40 CFR Sec. 261.36 (d)(4) are 
available at the claimant's facility. Based upon my inquiry of the 
individuals immediately responsible for obtaining the information, 
the information is, to the best of my knowledge and belief, true, 
accurate, and complete. I am aware that there are significant 
penalties for submitting false information, including the 
possibility of fine and imprisonment for knowing violations.''; or

    (2) For every retest required under Sec. 261.36(d)(2), the claimant 
must document that the concentrations of all constituents retested as 
required under Sec. 261.36(d)(3) met the applicable levels in appendix 
X to this part 261 at the waste's point of generation, must include 
information supporting this claim from the waste's generator if the 
generator is not the person asserting the claim, and must retain such 
documentation in files on-site for three years after the date of the 
relevant test.
    (f) Nothing in this paragraph preempts, overrides, or otherwise 
negates the provision in Sec. 262.11 of this chapter, which requires 
any person who generates a solid waste to determine if that waste is a 
hazardous waste.
    (g) In an enforcement action, the burden of proof to establish 
conformance with the exemption criteria shall be on the claimant.
    6. A new Sec. 261.37 is added to read as follows:


Sec. 261.37  Exemption for listed hazardous wastes containing low 
concentrations of hazardous constituents and managed in landfills and 
monofills.

    (a) Any hazardous waste listed under this subpart, any mixture of 
such a listed waste with a solid waste, or any waste derived from the 
treatment, storage or disposal of such a listed waste is exempt from 
regulation as a hazardous waste under parts 262-266 and 270 of this 
chapter if it meets the requirements in Sec. 261.37(b) and (d) 
(including the requirement that all hazardous constituents present in 
the waste be at or below the levels listed in appendix XI to this part 
and that the waste be disposed in a landfill or monofill, but not a 
land application unit). To maintain the exemption, the waste must 
satisfy the conditions in Sec. 261.37(e). Any such waste which also 
meets the requirements of 261.37(f) is also exempt from the 
requirements of part 268 of this chapter.
    (b) Requirements for qualifying for an exemption--(1) Testing. (i) 
For each waste for which an exemption is claimed, the claimant must 
test for all of the constituents on appendix XI to this part 261 except 
those that the claimant determines should not be present in the waste. 
The claimant is required to document the basis of each determination 
that a constituent should not be present. No claimant may determine 
that any of the following categories of constituents should not be 
present:
    (A) Constituents identified in appendix VII to this part 261 as the 
basis for listing the waste for which exemption is sought;
    (B) Constituents listed in the table to Sec. 268.40 as regulated 
hazardous constituents for LDR treatment of the waste;
    (C) Constituents detected in any previous analysis of the same 
waste conducted by or on behalf of the claimant;
    (D) Constituents introduced into the process which generates the 
waste; and
    (E) Constituents which the claimant knows or has reason to believe 
are byproducts or side reactions to the process that generates the 
waste.

    Note: Any claim under this section must be valid and accurate 
for all hazardous constituents; a determination not to test for a 
hazardous constituent will not shield a claimant from liability 
should that constituent later be found in the waste.

    (ii) The claimant must develop a sampling and analysis plan for 
each 

[[Page 66443]]
waste for which an exemption is sought. The plan must identify:
    (A) Sampling procedures and locations sufficient to characterize 
the entire waste for which the exemption is claimed. Grab sampling is 
acceptable for this purpose.
    (B) Analytical methods that the claimant will use to determine, for 
wastewaters and nonwastewaters, the total concentration of each 
constituent on appendix XI to this part except for those constituents 
which the claimant has determined should not be present under 
Sec. 261.37(b)(1)(i).
    (iii) The claimant must conduct sampling and analysis in accordance 
with the plan.
    (iv) The results of the sampling and analysis must show, for both 
wastewaters and nonwastewaters, that all total constituent 
concentrations in the waste are at or below the exemption levels in 
appendix XI to this part 261 and, for nonwastewaters, that all 
leachable constituent concentrations are either:
    (A) At or below exemption levels in appendix XI to this Part 261, 
as determined by testing an extract using test method 1311 (the 
Toxicity Characteristic Leaching Procedure, set out in ``Test Methods 
for Evaluating Solid Waste, Physical/Chemical Methods'' (SW-846)), or
    (B) Estimated to be at or below exemption levels using the equation 
{(AxB)+(CxD)}/{B+(20xD)} < leach exit level, where A=concentration of 
the analyte in the liquid portion of the sample; B = Volume of the 
liquid portion of the sample; C=Concentration of the analyte in the 
solid portion of the sample; D = Weight of the solid portion of the 
sample.
    (2) Treatment requirements. Any waste that exits using an exit 
level on Table B to appendix XI to this Part 261 must meet the 
treatment standard for such a constituent under Sec. 268.40 of this 
chapter, regardless of whether or not the waste is intended for land 
disposal, unless the claimant meets the exemption requirements in 
Sec. 261.37(f).
    (3) Public Notice. The claimant must submit for publication in a 
major newspaper of general circulation, local to the claimant, a notice 
entitled ``Notification of Exemption Claim for Listed Hazardous Wastes 
Containing Low Concentrations of Hazardous Constituents and Managed in 
Landfills and Monofills Under the Resource Conservation and Recovery 
Act'' containing the following information:
    (i) The name, address, and RCRA ID number of the claimant's 
facility;
    (ii) The applicable EPA Hazardous Waste Code of the waste for which 
the exemption is claimed and the narrative description associated with 
the listing from this part 261 subpart D;
    (iii) A brief, general description of the manufacturing, treatment, 
or other process or operation producing the waste;
    (iv) An estimate of the average and maximum monthly and annual 
quantities of the waste claimed to be exempt;
    (v) The name and mailing address of the agency to which the 
claimant is submitting the notification required under 
Sec. 261.37(b)(4);
    (vi) The following statement:

    The exemption for this waste from the hazardous waste regulatory 
scheme is conditioned disposing of the waste in a landfill or 
monofill (and not a land application unit.)

    (4) Notification to implementing agency. Prior to managing any 
waste as exempt under this section, the claimant must send to the 
Director via certified mail or other mail service that provides written 
confirmation of delivery a notification of the exemption claim meeting 
the following requirements:
    (i) The name, address, and RCRA ID number of the person claiming 
the exemption;
    (ii) The applicable EPA Hazardous Waste Codes;
    (iii) A brief description of the process that generated the waste;
    (iv) An estimate of the average and maximum monthly and annual 
quantities of each waste claimed to be exempt;
    (v) Documentation for any claim that a constituent is not present 
as described under Sec. 261.37(b)(1)(i);
    (vi) The results of all analyses and estimates of constituent 
concentrations required under Sec. 261.37(b)(1)(iv) and all 
quantitation limits achieved;
    (vii) Documentation that any waste that exits using a constituent 
exit level from Table B to appendix XI to this part have met the 
applicable treatment standards in Sec. 268.40, of this chapter, unless 
the claimant is also claiming the exemption under Sec. 261.37(f);
    (viii) Evidence that the public notification requirements of 
Sec. 261.37(b)(3) have been satisfied; and
    (ix) The following statement signed by the person claiming the 
exemption or his authorized representative:

    Under penalty of criminal and civil prosecution for making or 
submitting false statements, representations, or omissions, I 
certify that the requirements of Sec. 261.37(b) have been met, 
including the requirement that all hazardous constituents present in 
the waste are at or below the levels listed on appendix XI to this 
part, for all listed wastes identified in this notification. I also 
certify that arrangements have been made to dispose of the waste in 
a landfill or monofill (and not a land application unit). Copies of 
the records and information required at Sec. 261.37 (e)(7) are 
available) at the claimant's facility. Based upon my inquiry of the 
individuals immediately responsible for obtaining the information, 
the information is, to the best of my knowledge and belief, true, 
accurate, and complete. I am aware that there are significant 
penalties for submitting false information, including the 
possibility of fine and imprisonment for knowing violations.

    (5) The claimant must receive confirmation of delivery for the 
notification required under Sec. 261.37 (b)(4).
    (c) Tracking, storage, treatment and other management prior to 
disposal. Until a listed hazardous waste meeting the requirements of 
Sec. 261.37(b) is placed in a landfill or monofill, it remains subject 
to all requirements of parts 262-266 and 270 of this chapter. The waste 
is also subject to the requirements of part 268 of this chapter unless 
it qualifies for an exemption under Sec. 261.37(f).
    (d) Disposal in a landfill or monofill. The claimant must ensure 
that any listed waste meeting the requirements of Sec. 261.37(b) for 
which an exemption is sought is disposed of in either a landfill or 
monofill (and not a land application unit). The landfill or monofill 
need not be subject to regulation as a hazardous waste management unit. 
The waste becomes exempt as soon as it is placed in a landfill or 
monofill unit.
    (e) Conditions for maintaining the exemption. To maintain any 
exemption claimed pursuant to this section, the claimant must satisfy 
the following conditions:
    (1) Compliance with modified hazardous waste manifest system. If 
the landfill or monofill in which the waste is disposed is not a 
hazardous waste disposal unit subject to part Sec. 264.71-264.72 or 
Sec. 265.71-265.72 of this chapter, the claimant must:
    (i) Ensure that the manifest form is returned from the disposal 
facility, and
    (ii) Obtain information showing that the disposal facility 
designated on the manifest received the waste for which the exemption 
is sought and placed it in either a landfill or monofill (and not a 
land treatment unit).
    (2) Changes in information. The claimant must submit to the 
Director any change in any information submitted under 
Sec. 261.37(b)(4) within ten business days of the claimant's first 
knowledge of the change.
    (3) Schedule for retesting. The claimant must retest the waste for 
which the exemption was claimed on the following schedule: 

[[Page 66444]]

    (i) For the first three years of the exemption, the claimant must:
    (A) Test wastes generated at the time the exemption is claimed in 
volumes greater than 10,000 tons/year on a quarterly basis;
    (B) Test wastes generated at the time the exemption is claimed in 
volumes greater than 1000 tons/year but less than 10,000 tons/year must 
on a semi-annual basis;
    (C) Test wastes generated at the time the volume is claimed in 
volumes less than 1000 tons/year on an annual basis.
    (ii) After the first three years of an exemption, the claimant must 
retest the waste for which the exemption was claimed on an annual 
basis.
    (4) For every retest the claimant must prepare and comply with a 
sampling and analysis plan meeting the requirements of 
Sec. 261.37(b)(1)(ii) and determine the concentration of:
    (i) Each constituent from Table A to appendix XI to this part that 
was detected in the initial test within an order of magnitude below 
either its total or leachable exemption level and each constituent from 
Table B to appendix XI to this part that is identified as a basis for 
listing the waste on appendix VII to this part or is listed as a 
regulated hazardous constituent for the waste in the table of 
``Treatment Standards for Hazardous Wastes'' in Sec. 268.40 of this 
chapter; and
    (ii) Any other constituent that the claimant has reason to believe 
may be newly present in the waste since the most recent test.
    (5) Exemption levels.--The concentrations of all constituents 
tested must meet the criteria set out in Sec. 261.37(b)(1)(iv).
    (6) Treatment requirements.--Any waste exiting by using an exit 
level for a hazardous constituent from Table B to Appendix XI to this 
part must meet the treatment requirements for such a constituent under 
Sec. 268.40 of this chapter prior to exit regardless of whether or not 
the waste is intended for land disposal, unless the claimant meets the 
exemption requirements in Sec. 261.37(f).
    (7) Records.--The claimant must maintain records of the following 
information in files on-site for three years after the date of the 
relevant test:
    (i) For initial testing, all information submitted under 
Sec. 261.37(b)(4) and all revisions to such material submitted under 
Sec. 261.37(e)(2), all information obtained under Sec. 261.37(e)(1), 
and all information required to be maintained under 
Sec. 261.37(e)(7)(iii);
    (ii) For retests:
    (A) All volume determinations made for the purpose of determining 
testing frequency under Sec. 261.37(e)(3);
    (B) All sampling and analysis plans required under 
Sec. 261.37(e)(4);
    (C) All analytical results and estimates of leachable 
concentrations (if any) for constituents required to be assessed under 
Sec. 261.37 (e)(5);
    (D) Documentation showing that a waste exiting using any 
constituent exit level from Table B to Appendix XI to this part has met 
applicable treatment standards under Sec. 268.40 of this chapter, 
unless the claimant also claims the exemption under Sec. 261.37(f); and
    (iii) For both initial tests and retests, the claimant must also 
retain records of:
    (A) The dates and times waste samples were obtained, and, for total 
concentrations and leachable concentrations that were analyzed, the 
dates of the analyses;
    (B) The names and qualifications of the person(s) who obtained the 
samples;
    (C) A description of the temporal and spatial locations of the 
samples;
    (D) The name and address of the laboratory facility at which 
analyses of the samples were performed;
    (E) A description of the analytical methods used, including any 
clean-up and extraction methods;
    (F) All quantitation limits achieved and all other quality control 
results (including any method blanks, duplicate analyses, and matrix 
spikes), laboratory quality assurance data, and a description of any 
deviations from published analytical methods or from the plan which 
occurred; and
    (G) All laboratory documentation that supports the analytical 
results, unless a contract between the claimant and the laboratory 
provides for the documentation to be maintained by the laboratory for 
the period specified in Sec. 261.37 (b)(2) and also provides for the 
availability of the documentation to the claimant upon request. Failure 
to satisfy any of these conditions voids the exemption and requires 
management of the waste for which the exemption has been claimed as 
hazardous waste. Submission of notification to the Director that all 
waste conditions have been satisfied re-establishes the exemption for 
all waste generated after that date.
    (f) Exemption from part 268 requirements.--If all hazardous 
constituent levels in a waste qualifying for exemption are at or below 
the appendix XI to this part concentration levels at the waste's point 
of generation, prior to any mixing with other solid or hazardous wastes 
and prior to any treatment, the waste is exempt from all requirements 
of part 268 of this chapter. The claimant also must meet the following 
documentation requirements:

    (1) For initial tests, in place of the certification required at 
Sec. 261.37 (b)(4)(ix), the claimant must submit the following 
statement signed by the person claiming the exemption or his authorized 
representative and, if the claimant is not the generator of the waste, 
also signed by the generator or his authorized representative:

    Under penalty of criminal and civil prosecution for making or 
submitting false statements, representations, or omissions, I 
certify that, for the waste identified in this notification, the 
concentration of all constituents assessed as required under 
Sec. 261.37 (b)(1)(iv) met the applicable levels in appendix XI to 
this part 261 at the point of generation and that all other 
requirements of 40 CFR 261.37 (b) have been met. I also certify that 
arrangements have been made to dispose of the waste in a landfill or 
monofill (and not a land application unit). Copies of the records 
and information required at 40 CFR 261.37 (e)(7) are available at 
the claimant's facility. Based upon my inquiry of the individuals 
immediately responsible for obtaining the information, the 
information is, to the best of my knowledge and belief, true, 
accurate, and complete. I am aware that there are significant 
penalties for submitting false information, including the 
possibility of fine and imprisonment for knowing violations.''; and

    (2) For every retest required under Sec. 261.37(e)(3), the claimant 
must document that the concentrations of all constituents retested as 
required under Sec. 261.37(e)(4) met the applicable levels in appendix 
XI to this part 261 at the waste's point of generation, must include 
information supporting this claim from the waste's generator if the 
generator is not the person asserting the claim, and must retain such 
documentation in files on-site for three years after the date of the 
relevant test.

    (g) Nothing in this paragraph preempts, overrides, or otherwise 
negates the provision in Sec. 262.11 of this chapter, which requires 
any person who generates a solid waste to determine if that waste is a 
hazardous waste.

    (h) In an enforcement action, the burden of proof to establish 
conformance with the exemption criteria shall be on the claimant.

    7. Appendix X is added to read as follows:

                                                                                                                                                        

[[Page 66445]]
                                                                       Appendix X                                                                       
                                                Table A.--Modeled or Extrapolated Risk-Based Exit Levels                                                
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                             MCL benchmark option                                 Toxicity benchmark option             
                                           -------------------------------------------------------------------------------------------------------------
        CAS No.                 Name            Wastewater                 Nonwastewater               Wastewater                Nonwastewater          
                                           -------------------------------------------------------------------------------------------------------------
                                               Totals (mg/l)     Totals (mg/kg)     Leach (mg/l)      Totals (mg/l)    Totals (mg/kg)     Leach (mg/l)  
--------------------------------------------------------------------------------------------------------------------------------------------------------
83-32-9................  Acenaphthene.....          31              9500                 5                31              9500                 5        
208-96-8...............  Acenaphthylene...       (\1\)                 4             (\1\)             (\1\)                 4             (\1\)        
67-64-1................  Acetone..........          16             17000                 6                16             17000                 6        
75-05-8................  Acetonitrile.....           0.78            920                 0.3               0.78            920                 0.3      
98-86-2................  Acetophenone.....          17              1200                 6                17              1200                 6        
75-36-5................  Acetyl chloride..       (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
591-08-2...............  Acetyl-2-               (\1\)             (\1\)                 6             (\1\)             (\1\)                 6        
                          thiourea, 1-.                                                                                                                 
53-96-3................  Acetylaminofluore           0.028             3             (\1\)                 0.028             3             (\1\)        
                          ne, 2-.                                                                                                                       
107-02-8...............  Acrolein.........       (\1\)                 3          ................     (\1\)                 3          ................
79-06-1................  Acrylamide.......       (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
107-13-1...............  Acrylonitrile....       (\1\)                 0.96          (\1\)             (\1\)                 0.96          (\1\)        
1402-68-2..............  Aflatoxins.......       (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
116-06-3...............  Aldicarb.........       (\1\)             (\1\)                 0.54          (\1\)             (\1\)                 0.48     
309-00-2...............  Aldrin...........       (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
107-18-6...............  Allyl Alcohol....       (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
107-05-1...............  Allyl chloride...           0.074           260          ................         0.074           260          ................
92-67-1................  Aminobiphenyl, 4-           0.028             3             (\1\)                 0.028             3             (\1\)        
2763-96-4..............  Aminomethyl-3-          (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
                          isoxazolol, 5-.                                                                                                               
504-24-5...............  Aminophyridine, 4-      (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
                          .                                                                                                                             
61-82-5................  Amitrole.........       (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
62-53-3................  Aniline..........           0.053             4                 0.017             0.053             4                 0.017    
120-12-7...............  Anthracene.......       (\1\)                 4             (\1\)             (\1\)                 4             (\1\)        
7440-36-0..............  Antimony.........           0.14              9                 0.053             0.14              9                 0.053    
140-57-8...............  Aramite..........          15              6900                11                15              6900                11        
7440-38-2..............  Arsenic..........           0.38          (\1\)                 0.15          (\1\)             (\1\)             (\1\)        
2465-27-2..............  Auramine.........       (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
115-02-6...............  Azaserine........       (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
7440-39-3..............  Barium...........          28              2100                11                33              2100                16        
71-43-2................  Benzene..........           0.021           110                 0.009             0.018           110                 0.0054   
92-87-5................  Benzidine........       (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
106-51-4...............  Benzoquinone, p-.          15              6900                11                15              6900                11        
98-07-7................  Benzotrichloride.       (\1\)               140             (\1\)             (\1\)               140             (\1\)        
50-32-8................  Benzo(a)pyrene...           0.0023            0.23              0.0036            0.0023            0.23          (\1\)        
205-99-2...............  Benzo(b)-                   0.00081           4                 0.000066          0.00081           4                 0.000066 
                          fluoranthene.                                                                                                                 
205-82-3...............  Benzo(j)-                   0.0029            4                 0.0012            0.0029            4             (\1\)        
                          fluoranthene.                                                                                                                 
207-08-9...............  Benzo(k)-                   0.0029            4                 0.0012            0.0029            4             (\1\)        
                          fluoranthene.                                                                                                                 
191-24-2...............  Benzo[g,h,i]-               0.0029            4                 0.0012            0.0029            4             (\1\)        
                          perylene.                                                                                                                     
100-51-6...............  Benzyl alcohol...          39              2700                15                39              2700                15        
100-44-7...............  Benzyl chloride..           1                38                15                 1                38                15        
56-55-3................  Benz(a)                     0.00072           0.1           (\1\)                 0.00072           0.1           (\1\)        
                          anthracene.                                                                                                                   
225-51-4...............  Benz[c]acridine..           0.0029            4                 0.0012            0.0029            4             (\1\)        
7440-41-7..............  Beryllim.........           0.00083       (\1\)                 o.00032           0.00083       (\1\)                 0.00032  
39638-32-9.............  Bis (2-                     0.007             0.94              0.0019            0.007             0.94              0.0019   
                          chloroisopropyl)                                                                                                              
                          ether.                                                                                                                        
111-44-4...............  Bis(2-                      0.00065           0.12              0.00036           0.00065           0.12              0.00036  
                          chlorethyl)ether.                                                                                                             
117-81-7...............  Bis(2-                      0.00044         230                 0.11              0.00044         230                 0.0011   
                          ethylhexyl)phtha                                                                                                              
                          late.                                                                                                                         
542-88-1...............  Bis(chloromethyl)       (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
                          ether.                                                                                                                        
598-31-2...............  Bromoacetone.....           0.024            31                 0.012             0.023            31                 0.015    
75-27-4................  Bromodichlorometh           0.0085           19                 0.0025            0.0085           19                 0.0025   
                          ane.                                                                                                                          
75-25-2................  Bromoform                   0.064           170                 0.018             0.064           170                 0.018    
                          (Tribromomethane                                                                                                              
                          ).                                                                                                                            
101-55-3...............  Bromophyenyl                0.024            31                 0.012             0.023            31                 0.015    
                          ether, 4-.                                                                                                                    
357-57-3...............  Brucine..........       (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
71-36-3................  Butanol..........          16              1800                 6                16             18000                 6        
88-85-7................  Butyl-4,6-                  0.034           770                 0.011             0.19            770                 0.064    
                          dinitrophenol, 2-                                                                                                             
                          sec- (Dinoseb).                                                                                                               
85-68-7................  Butylbenzylphthal         240                87                64               240                87                64        
                          ate.                                                                                                                          
7440-43-9..............  Cadmium..........           0.038            14                 0.015             0.24             14                 0.11     
86-74-8................  Carbazole........       (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        

[[Page 66446]]
                                                                                                                                                        
75-15-0................  Carbon disulfide.           0.74            330                 6                 0.74            330                 6        
353-50-4...............  Carbon                  (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
                          oxyfluoride.                                                                                                                  
56-23-5................  Carbon                      0.012             9                 0.012             0.012             9                 0.0016   
                          tetrachloride.                                                                                                                
75-87-6................  Chloral..........       (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
305-03-3...............  Chlorambucil.....       (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
57-74-9................  Chlordane........       (\1\)                 0.0098            0.036         (\1\)                 0.0098            0.00016  
494-03-1...............  Chlornaphazin....       (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
126-99-8...............  Chloro-1,3-                 0.52            290          ................         0.52            290          ................
                          butadiene, 2-                                                                                                                 
                          (Chloroprene).                                                                                                                
107-20-0...............  Chloroacetaldehyd       (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
                          e.                                                                                                                            
106-47-8...............  Chloroaniline, p-           0.42            140                 0.16              0.42            140                 0.16     
108-90-7...............  Chlorobenzene....           0.68           2500                 0.19              2              2500                 1        
510-15-6...............  Chlorobenzilate..           0.054             7                 0.0057            0.054             7                 0.0057   
124-48-1...............  Chlorodibromometh           0.0066           28                 0.0018            0.0066           28                 0.0018   
                          ane.                                                                                                                          
75-00-3................  Chloroethane                0.024            31                 0.012             0.023            31                 0.015    
                          (ethyl chloride).                                                                                                             
110-75-8...............  Chloroethyl vinyl       (\1\)               140             (\1\)             (\1\)               140             (\1\)        
                          ether, 2-.                                                                                                                    
67-66-3................  Chloroform.......           0.0076            7                 0.017             0.0076            7                 0.017    
59-50-7................  Chloro-m-cresol,            0.27            140                 0.033             0.081           140                 0.032    
                          p-.                                                                                                                           
107-30-2...............  Chloromethyl            (\1\)                31             (\1\)             (\1\)                31             (\1\)        
                          methyl ether.                                                                                                                 
91-58-7................  Chloronaphthalene           0.27            140                 0.033             0.081           140                 0.032    
                          , 2-.                                                                                                                         
95-57-9................  Chlorophenol, 2-.           0.9             100                 0.32              0.9             100                 0.32     
7005-72-3..............  Chlorophenyl                0.024            31                 0.012             0.023            31                 0.015    
                          phenyl ether, 4-.                                                                                                             
5344-82-1..............  Chlorophenyl            (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
                          thiourea, 1-0-.                                                                                                               
542-76-7...............  Chloropropionitri           0.27            140             (\1\)             (\1\)               140             (\1\)        
                          le, 3-.                                                                                                                       
7440-47-3..............  Chromium.........           0.62             10                 0.24              1                10                 0.48     
218-01-9...............  Chrysene.........           0.1              35                 0.0012            0.1              35                 0.0012   
6358-53-8..............  Citrus red No. 2.       (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
7440-48-4..............  Cobalt...........           0.62              9             (\1\)                 1                 9             (\1\)        
7440-50-8..............  Copper...........         670                 6              1100               670                 6              1100        
108-39-4...............  Cresol, m-.......           8             22000                 3                 8             22000                 3        
95-48-7................  Cresol, o-.......           8             27000                 3                 8             27000                 3        
106-44-5...............  Cresol, p-.......           0.84           2600                 0.32              0.84           2600                 0.32     
4170-30-3..............  Crotonaldehyde...           8              1200                 6                 8              1200                 6        
57-12-5................  Cyanide..........       (\1\)                20             (\1\)             (\1\)                20             (\1\)        
14901-08-7.............  Cycasin..........       (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
108-94-1...............  Cyclohexanone....       (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
131-89-5...............  Cyclohexyl-4,6-         (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
                          dinitrophenol, 2-                                                                                                             
                          .                                                                                                                             
50-18-0................  Cyclophosphamide.       (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
20830-81-3.............  Daunomycin.......       (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
72-54-8................  DDD..............           0.00013           0.0065         2800                 0.00013           0.0065         2800        
53-19-0................  DDD (o,p').......       (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
72-55-9................  DDE..............       (\1\)                 0.00094           0.000062      (\1\)                 0.00094           0.00062  
3424-82-6..............  DDE (o,p').......       (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
50-29-3................  DDT..............       (\1\)                 0.0032            0.0054        (\1\)                 0.0032            0.0054   
789-02-6...............  DDT (o,p').......       (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
2303-16-4..............  Diallate.........           0.26              1                 0.46              0.26              1                 0.46     
132-64-9...............  Dibenzofuran.....           8             27000                 2                 8             27000                 3        
192-64-9...............  Dibenzo[a,e]pyren           0.0029            4                 0.0012            0.0029            4             (\1\)        
                          e.                                                                                                                            
189-64-0...............  Dibenzo[a,h]pyren           0.0029            4                 0.0012            0.0029            4             (\1\)        
                          e.                                                                                                                            
189-55-9...............  Dibenzo[a,i]pyren           0.0029            4                 0.0012            0.0029            4             (\1\)        
                          e.                                                                                                                            
194-59-2...............  Dibenzo[c,g]carba       (\1\)                 4             (\1\)             (\1\)                 4             (\1\)        
                          zole, 7H-.                                                                                                                    
226-36-8...............  Dibenz(a,h)acridi           0.0029            4                 0.0012            0.0029            4             (\1\)        
                          ne.                                                                                                                           
53-70-3................  Dibenz(a,h)anthra       (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
                          cene.                                                                                                                         
224-42-0...............  Dibenz[a,j]acridi           0.0029            4                 0.0012            0.0029            4             (\1\)        
                          ne.                                                                                                                           
96-12-8................  Dibromo-3-                  0.0022            0.66              0.00038           0.00066           0.66          (\1\)        
                          chloropropane,                                                                                                                
                          1,2-.                                                                                                                         
764-41-0...............  Dichloro-2-                 0.024            31                 0.012             0.023            31                 0.016    
                          butene, 1,4-.                                                                                                                 
110-57-6...............  Dichloro-2-                 0.024            31                 0.012             0.023            31                 0.015    
                          butene, trans-                                                                                                                
                          1,4-.                                                                                                                         

[[Page 66447]]
                                                                                                                                                        
96-23-1................  Dichloro-2-                 0.27            140                 0.033             0.081           140                 0.032    
                          propanol, 1,3-.                                                                                                               
95-50-1................  Dichlorobenzene,            8             50000                 2                15             50000                 6        
                          1,2-.                                                                                                                         
541-73-1...............  Dichlorobenzene,            0.024            31                 0.012             0.023            31                 0.015    
                          1,3-.                                                                                                                         
106-46-7...............  Dichlorobenzene,            1                64                 0.22              0.056            64                 0.011    
                          1,4-.                                                                                                                         
91-94-1................  Dichlorobenzidine           0.0037        (\1\)             (\1\)                 0.0037        (\1\)             (\1\)        
                          , 3,3').                                                                                                                      
75-71-8................  Dichlorodifluorom          15              8100                12                15              8100                12        
                          ethane.                                                                                                                       
75-34-3................  Dichloroethane,             0.00016          24                 0.0006            0.00016          24                 0.00006  
                          1,1-.                                                                                                                         
107-06-2...............  Dichloroethane,             0.007             6                 0.009             0.00016           6                 0.00006  
                          1,2-.                                                                                                                         
75-35-4................  Dichloroethylene,           0.0035            3                 0.013             0.00059           3                 0.00018  
                          1,1-.                                                                                                                         
156-59-2...............  Dichloroethylene,           0.29           5400                 0.11              2              5400                 0.64     
                          cis-1,2-.                                                                                                                     
156-60-5...............  Dichloroethylene,           0.42          14000                 0.16              3             14000                 1        
                          trans-1,2-.                                                                                                                   
111-91-1...............  Dichloromethoxy             0.024            31                 0.012             0.023            31                 0.015    
                          ethane.                                                                                                                       
98-87-3................  Dichloromethylben           0.024            31                 0.012             0.023            31                 0.015    
                          zene (benzal                                                                                                                  
                          chloride).                                                                                                                    
120-83-2...............  Dichlorophenol,             0.62            770                 0.18              0.62            770                 0.18     
                          2,4-.                                                                                                                         
87-65-0................  Dichlorophenol,             0.024            31                 0.012             0.023            31                 0.015    
                          2,6-.                                                                                                                         
94-75-7................  Dichlorophenoxyac           0.27           3100                 0.11              2              3100                 0.6      
                          etic acid, 2,4-                                                                                                               
                          (2,4-D).                                                                                                                      
78-87-5................  Dichloropropane,            0.12             17                 0.012             0.023            17                 0.0023   
                          1,2-.                                                                                                                         
542-75-6...............  Dichloropropene,            0.0028           32             (\1\)                 0.0028           32             (\1\)        
                          1,3-.                                                                                                                         
10061-01-5.............  Dichloropropene,            0.0049            3              1200                 0.0049            3              1200        
                          cis-1,3-.                                                                                                                     
10061-02-6.............  Dichloropropene,            0.0049            3              1200                 0.0049            3              1200        
                          trans-1,3-.                                                                                                                   
60-57-1................  Dieldrin.........           0.000059          0.0018            0.54              0.000059          0.0018            0.54     
1464-53-5..............  Diepoxybutane,             15              6900                11                15              6900                11        
                          1,2,3,4- (2,2'-                                                                                                               
                          bioxirane).                                                                                                                   
84-66-2................  Diethyl phthalate         190              4500                54               190              4500                54        
311-45-5...............  Diethyl-p-              (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
                          nitrophenyl                                                                                                                   
                          phosphate.                                                                                                                    
56-53-1................  Diethylstilbestro       (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
                          l.                                                                                                                            
94-58-6................  Dihydrosafrole...          15              6900                11                15              6900                11        
60-51-5................  Dimethoate.......          29                 2                 0.77             29                 2                 0.77     
131-11-3...............  Dimethyl                   78                 3                30                78                 3                30        
                          phthalate.                                                                                                                    
77-78-1................  Dimethyl sulfate.       (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
60-11-7................  Dimethylaminoazob           0.028             3             (\1\)                 0.028             3             (\1\)        
                          enzene, p-.                                                                                                                   
119-93-7...............  Dimethylbenzidine       (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
                          , 3,3'.                                                                                                                       
57-97-6................  Dimethylbenz(a)an       (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
                          thracene, 7,12.                                                                                                               
79-44-7................  Dimethylcarbamoyl       (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
                          chloride.                                                                                                                     
122-09-8...............  Dimethylphenethyl           0.16             20                 0.11              0.16             20                 0.11     
                          amine, alpha,                                                                                                                 
                          alpha-.                                                                                                                       
105-67-9...............  Dimethylphenol,             4             11000                 1                 4             11000                 1        
                          2,4-.                                                                                                                         
119-90-4...............  Dimethyoxybenzidi           0.034         (\1\)                 0.01              0.034         (\1\)                 0.01     
                          ne, 3,3-.                                                                                                                     
84-74-2................  Di-n-butyl                880             90000               100               230             90000                25        
                          phthalate.                                                                                                                    
99-65-0................  Dinitrobenzene,             0.017             6                 0.0064            0.017             6                 0.0064   
                          1,3-.                                                                                                                         
100-25-4...............  Dinitrobenzene,         (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
                          1,4-.                                                                                                                         
534-52-1...............  Dinitro-o-cresol,       (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
                          4,6-.                                                                                                                         
51-28-5................  Dinitrophenol,              0.27             56                 0.11              0.27             56                 0.11     
                          2,4-.                                                                                                                         
121-14-2...............  Dinitrotoluene,             0.29            210                 0.11              0.29            210                 0.11     
                          2,4-.                                                                                                                         
606-20-2...............  Dinitrotoluene,             0.17             86                 0.064             0.17             86                 0.064    
                          2,6-.                                                                                                                         
117-84-0...............  Di-n-octyl                  0.002          4500                 0.1               0.002          4500                 0.1      
                          phthalate.                                                                                                                    
123-91-1...............  Dioxane, 1,4-....           0.042            13                 0.014             0.042            13                 0.014    
122-39-4...............  Diphenylamine....          15              1200                 3                15             12000                 3        
122-66-7...............  Diphenylhydrazine           0.16             20                 0.11              0.16             20                 0.11     
                          , 1,2-.                                                                                                                       
298-04-4...............  Disulfoton.......           0.013            43                13                 0.013            43                13        
541-53-7...............  Dithiobiuret.....       (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
                         D, salts, esters,           0.0069        (\1\)                 0.54              0.0069        (\1\)                 0.48     
                          2,4-.                                                                                                                         
115-29-7...............  Endosulfan.......           6                73                 0.94              6                73                 0.94     
959-98-8...............  Endosulfan I.....           0.0069            0.19              0.54              0.0069            0.19              0.48     
33213-65-9.............  Endosulfan II....           0.0069            0.19              0.54              0.0069            0.19              0.48     
1031-07-8..............  Endosulfan                  0.0069            0.19              0.54              0.0069            0.19              0.48     
                          sulfate.                                                                                                                      
145-73-3...............  Endothall........       (\1\)             (\1\)                 0.54          (\1\)             (\1\)                 0.48     
72-20-8................  Endrin...........           0.073             0.26             24                 0.073             0.26             32        
7421-93-4..............  Endrin aldehyde..           0.0069            0.19              0.54              0.0069            0.19              0.48     
53494-70-5.............  Endrin ketone....           0.0069            0.19              0.54              0.0069            0.19              0.48     
106-89-8...............  Epichlorohydrin..           0.34             44              5400                 0.34             44              5400        
51-43-4................  Epinephrine......       (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
110-80-5...............  Ethoxyethanol, 2-          15              6900                15                15              6900                15        
141-78-6...............  Ethyl acetate....         390            270000               110               390            270000               110        
51-79-6................  Ethyl carbamate..          15              6900                11                15              6900                11        
107-12-0...............  Ethyl cyanide               0.16             20                 0.11              0.16             20                 0.11     
                          (propionitrile).                                                                                                              
60-29-7................  Ethyl ether......          27             41000                11                27             41000                11        
97-63-2................  Ethl methacrylate          24              3400                 7                24              3400                7         

[[Page 66448]]
                                                                                                                                                        
62-50-0................  Ethyl                       0.0055        (\1\)             12000                 0.0055        (\1\)             12000        
                          methanesulfonate.                                                                                                             
100-41-4...............  Ethylbenzene.....           8            550000                 2                39            550000                 8        
 106-93-4..............  Ethylene                    0.00093           0.0075            0.00075           0.00036           0.0075        (\1\)        
                          Dibromide.                                                                                                                    
 75-21-8...............  Ethylene oxide...          15              6900                11                15              6900                11        
 96-45-7...............  Ethylene thiourea       (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
 151-56-4..............  Ethyleneimine           (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
                          (aziridine).                                                                                                                  
 52-85-7...............  Famphur..........       (\1\)             (\1\)                 0.54 B        (\1\)             (\1\)                 0.48     
 640-19-7..............  Fluoracetamide, 2-      (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
                          .                                                                                                                             
 62-74-8...............  Fluoracetic acid,       (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
                          sodium salt.                                                                                                                  
 206-44-0..............  Fluoranthene.....          28              6000                 2                28              6000                 2        
 86-73-7...............  Fluorene.........          22             90000                 3                22             90000                 3        
 16984-48-8............  Fluoride.........  ..................  ................  ................  ................  ................  ................
 50-00-0...............  Formaldehyde.....       (\1\)                49                11             (\1\)                49                11        
 64-18-6...............  Formia Acid......         270            300000               110               270            300000               110        
 765-34-4..............  Glycidylaldehyde.       (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
 319-86-8..............  HCH, delta-......           0.0069            0.19              0.54              0.0069            0.19              0.48     
 76-44-8...............  Heptachlor.......       (\1\)                 8          ................     (\1\)                 8          ................
 1024-57-3.............  Heptachlor                  0.00053           0.026            66                 0.00053           0.026             0.45     
                          epoxide.                                                                                                                      
 87-68-3...............  Hexachloro-1,3-             0.0079           36                 0.0069            0.0079           36                 0.0069   
                          butadiene.                                                                                                                    
 118-74-1..............  Hexachlorobenzene       (\1\)             (\1\)                 0.018         (\1\)             (\1\)             (\1\)        
 319-84-6..............  Hexachloro-                 0.00014           0.0033            0.11              0.00014           0.033             0.11     
                          cyclohexane,                                                                                                                  
                          alpha- (alpha-                                                                                                                
                          BHC).                                                                                                                         
 319-85-7..............  Hexach- lorocyclo-          0.00044           0.12              0.00021           0.00044           0.12              0.00021  
                           hexane, beta-                                                                                                                
                          (beta-BHC).                                                                                                                   
 58-89-9...............  Hexach- lorocyc-            0.00078           0.1               2                 0.00078           0.1               0.69     
                          lohexane, gamma-                                                                                                              
                          (Lindane).                                                                                                                    
 77-47-4...............  Hexach- lorocyc-            0.0052         1500          ................         0.0052         1500          ................
                          lopentadiene.                                                                                                                 
 67-72-1...............  Hexachloroethane.           0.049            81                 0.033             0.049            81                 0.033    
 70-30-4...............  Hexachlorophene..       (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
 1888-71-7.............  Hexachloropropene           0.27            140                 0.033             0.081           140                 0.032    
 757-58-4..............  Hexae- thylte-          (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
                          traphosphate.                                                                                                                 
 591-75-6..............  Hexanone, 2-.....           8              1200                 6                 8              1200                 6        
 302-01-2..............  Hydrazine........       (\1\)                20             (\1\)             (\1\)                20             (\1\)        
 193-39-5..............  Indeno(1,2,3-cd)            0.0029            4             (\1\)                 0.0029            4             (\1\)        
                          pyrene.                                                                                                                       
 74-88-4...............  Iodomethane......           0.024            31                 0.012             0.023            31                 0.015    
 78-83-1...............  Isobutyl alcohol.          39             55000                15                39             55000                15        
 465-73-6..............  Isodrin..........       (\1\)             (\1\)                 0.54          (\1\)             (\1\)                 0.48     
 78-59-1...............  Isophorone.......           0.53            740                 0.16              0.53            740                 0.16     
 120-58-1..............  Isosafrole.......          15              6900                11                15              6900                11        
 143-50-0..............  Kepone...........       (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
 303-43-4..............  Lasiocarpine.....       (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
 7439-92-1.............  Lead.............          30               570                12                30               570                12        
 108-31-6..............  Maleic anhydride.       (\1\)              6900             (\1\)             (\1\)              6900             (\1\)        
 123-33-1..............  Maleic hydrazide.           0.16             20                 0.11              0.16             20                 0.11     
 109-77-3..............  Malononitrile....           0.16             20                 0.11              0.16             20                 0.11     
 148-82-3..............  Melphalan........       (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
 7439-97-6.............  Mercury..........           0.06              0.6               0.023             0.3               0.6               0.14     
 126-98-7..............  Methacrylonitrile           0.016             9             (\1\)                 0.016             9             (\1\)        
 74-93-1...............  Methanethiol.....       (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
 67-56-1...............  Methanol.........          78            140000                30                78            140000                30        
 91-80-5...............  Methapyrilene....           0.16             20                 0.11              0.16             20                 0.11     
 16752-77-5............  Methomyl.........       (\1\)             (\1\)                 0.54          (\1\)             (\1\)                 0.48     
 72-43-5...............  Methoxychlor.....           7                19          ................         7                19          ................
 74-83-9...............  Methyl bromide              0.37            500                 0.92              0.37            500                 0.92     
                          (Bromomethane).                                                                                                               
 74-87-3...............  Methyl chloride             0.096            91          ................         0.096            91          ................
                          (Chloromethane).                                                                                                              
 78-93-3...............  Methyl ethyl               78            110000                30                78            110000                30        
                          ketone.                                                                                                                       
 1338-23-4.............  Methyl ethyl            (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
                          ketone peroxide.                                                                                                              
 60-34-4...............  Methyl hydrazine.       (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
 108-10-1..............  Methyl isobutyl             8             17000                 3                 8             17000                 3        
                          ketone.                                                                                                                       

[[Page 66449]]
                                                                                                                                                        
 80-62-6...............  Methyl                     28             40000                 8                28             40000                 8        
                          methacrylate.                                                                                                                 
 66-27-3...............  Methyl                      0.12              2                 6                 0.12              2                 6        
                          methanesulfonate.                                                                                                             
 91-57-6...............  Methyl                  (\1\)                 4             (\1\)             (\1\)                 4             (\1\)        
                          naphthalene, 2-.                                                                                                              
 298-00-0..............  Methyl parathion.           0.66              1                23                 0.66              1                23        
 75-55-8...............  Methylaziridine,        (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
                          2-.                                                                                                                           
 56-49-5...............  Methylcholanthren       (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
                          e, 3-.                                                                                                                        
74-95-3................  Methylene bromide           0.029          8400                 0.0085            2              8400                 0.19     
75-09-2................  Methylene                   0.039           310                 0.09              0.039           310                 0.015    
                          chloride.                                                                                                                     
101-14-4...............  Methylenebis,           (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
                          4,4'-(2-                                                                                                                      
                          chloroaniline).                                                                                                               
70-25-7................  Methyl-nitro-           (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
                          nitrosoguanidine                                                                                                              
                          (MNNG).                                                                                                                       
56-04-2................  Methylthiouracil.       (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
50-07-7................  Mitomycin C......       (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
7439-98-7..............  Molybdenum.......           2               110                 2                 2               110                 2        
91-20-3................  Naphthalene......          14            120000                 3                14            120000                 3        
130-15-4...............  Naphthoquinone,            15              6900                11                15              6900                11        
                          1,4-.                                                                                                                         
86-88-4................  Naphthyl-2-             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
                          thiourea, 1-.                                                                                                                 
134-32-7...............  Naphthylamine, 1-           0.16             20                 0.11              0.16             20                 0.11     
91-59-8................  Naphthylamine, 2-           0.16             20                 0.11              0.16             20                 0.11     
7440-02-0..............  Nickel...........           4               110                 2                11               110                 5        
54-11-5................  Nicotine and                0.16             20                 0.11              0.16             20                 0.11     
                          salts.                                                                                                                        
88-74-4................  Nitroaniline, 2-.       (\1\)                 3             (\1\)             (\1\)                 3             (\1\)        
99-09-2................  Nitroaniline, 3-.       (\1\)                 3             (\1\)             (\1\)                 3             (\1\)        
100-01-6...............  Nitroaniline, 4-.           0.028             3             (\1\)                 0.028             3             (\1\)        
98-95-3-...............  Nitrobenzene.....           0.084            45                 0.032             0.084            45                 0.032    
55-86-7................  Nitrogen mustard.       (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
51-75-2................  Nitrogen mustard        (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
                          Hydrochloride                                                                                                                 
                          salt.                                                                                                                         
126-85-2...............  Nitrogen mustard        (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
                          N-Oxide.                                                                                                                      
302-70-5...............  Nitrogen mustard        (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
                          N-Oxide, HCI                                                                                                                  
                          salt.                                                                                                                         
55-63-0................  Nitroglycerine...       (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
99-55-8................  Nitro-o-                    0.028             3             (\1\)                 0.028             3             (\1\)        
                          toluidine, 5-.                                                                                                                
88-75-5................  Nitrophenol, 2-..           0.025             3             (\1\)                 0.0.25            3             (\1\)        
100-02-7...............  Nitrophenol, 4-..       (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
79-46-9................  Nitropropane, 2-.       (\1\)                 0.13       ................     (\1\)                 0.13       ................
56-57-5................  Nitroquinoline-1-           0.16             20                 0.11              0.16             20                 0.11     
                          oxide, 4-.                                                                                                                    
55-18-5................  Nitrosodiethylami       (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
                          ne.                                                                                                                           
62-75-9................  Nitrosodimethylam       (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
                          ine.                                                                                                                          
924-16-3...............  Nitrosodi-n-            (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
                          butylamine.                                                                                                                   
10595-95-6.............  Nitro- somethyle        (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
                          thylamine.                                                                                                                    
1116-54-7..............  N-Nitro- sodietha-      (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
                           nolamine.                                                                                                                    
621-64-7...............  N-Nitrosodi-n-          (\1\)                 0.023         (\1\)             (\1\)                 0.023         (\1\)        
                          propylamine.                                                                                                                  
86-30-6................  N-Nitro- sodiphe-           0.2            1300             (\1\)                 0.2            1300             (\1\)        
                          nylamine.                                                                                                                     
4549-40-0..............  N-Nitrosomethyl         (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
                          vinyl amine.                                                                                                                  
59-89-2................  N-                          0.16             20                 0.11              0.16             20                 0.11     
                          Nitrosomorpholin                                                                                                              
                          e.                                                                                                                            
759-73-9...............  N-Nitroso-N-            (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
                          ethylurea.                                                                                                                    
684-93-5...............  N-Nitroso-N-                0.16             20                 0.11              0.16             20                 0.11     
                          methylurea.                                                                                                                   
615-53-2...............  N-Nitroso-N-            (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
                          methylurethane.                                                                                                               
16543-55-8.............  N-                      (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
                          Nitrosonornicoti                                                                                                              
                          ne.                                                                                                                           
100-75-4...............  N-                      (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
                          Nitrosopiperidin                                                                                                              
                          e.                                                                                                                            
930-55-2...............  N-                      (\1\)                 0.053         (\1\)             (\1\)                 0.053         (\1\)        
                          Nitroopyrrolidin                                                                                                              
                          e.                                                                                                                            
13256-22-9.............  N-                      (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
                          Nitrososarcosine.                                                                                                             
103-85-5...............  N-Phenylthiourea.       (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
1615-80-1..............  N,N-                    (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
                          Diethylhydrazine.                                                                                                             
152-16-9...............  Octame- thylpyro-           0.27             31                 0.11              0.27             31                 0.11     
                          phospho- ramide.                                                                                                              
20816-12-0.............  Osmium Tetroxice.       (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
297-97-2...............  O,O-Diethyl O-              0.12              2                 6                 0.12              2                 6        
                          pyrazinyl                                                                                                                     
                          phosphorothioate.                                                                                                             
126-68-1...............  O,O,O-Triethyl              0.12          (\1\)                 6                 0.12          (\1\)                 6        
                          phosphorothioate.                                                                                                             
123-63-7...............  Paraldehyde......           8              1200                 6                 8              1200                 6        
56-38-2................  Parathion........           3                 0.13          12000                 3                 0.13          12000        
608-93-5...............  Pentachlorobenzen           5               210                 0.054             5               210                 0.054    
                          e.                                                                                                                            
76-01-7................  Pentachloroethane           0.024            31                 0.012             0.023            31                 0.015    
82-68-8................  Penta- chloro-              0.27             11             (\1\)                 0.081            11             (\1\)        
                          nitro-benzene                                                                                                                 
                          (PCNB).                                                                                                                       
87-86-5................  Pentachlorophenol           0.002             3                 0.00041           0.002             3                 0.00041  
62-44-2................  Phenacetin.......          15              6900                11                15              6900                11        
85-01-8................  Phenanthrene.....       (\1\)                 4             (\1\)             (\1\)                 4             (\1\)        
108-95-2...............  Phenol...........          84            160000                32                84            160000                32        
62-38-4................  Phenyl mercuric         (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
                          acetate.                                                                                                                      

[[Page 66450]]
                                                                                                                                                        
25265-76-3.............  Phenylenediamines           0.16             20                 0.11              0.16             20                 0.11     
                          (N.O.S.).                                                                                                                     
108-45-2...............  Phenylenediamine,           0.78            780                 0.3               0.78            780                 0.3      
                          m-.                                                                                                                           
106-50-3...............  Phenylenediamine,           0.16             20                 0.11              0.16             20                 0.11     
                          p-.                                                                                                                           
298-02-2...............  Phorate..........           0.11            160          ................         0.11            160          ................
                         Phosphorodithioic       (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
                          acid,                                                                                                                         
                          dimethylethylest                                                                                                              
                          er.                                                                                                                           
298-06-6...............  Phosphorodithioic       (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
                          acid, o-o-                                                                                                                    
                          diethyl ester.                                                                                                                
3288-58-2..............  Phosphorodithioic       (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
                          acid, o-o-                                                                                                                    
                          diethyl-s-methyl.                                                                                                             
2953-29-9..............  Phosphorodithioic       (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
                          acid, trimethyl                                                                                                               
                          ester.                                                                                                                        
85-44-9................  Phthalic                (\1\)              2400             (\1\)             (\1\)              2400             (\1\)        
                          anhydride.                                                                                                                    
109-06-8...............  Picoline, 2-.....           0.16             20                 0.11              0.16             20                 0.11     
1336-36-3..............  Polychlorinated         (\1\)             (\1\)                 0.009         (\1\)             (\1\)             (\1\)        
                          biphenyls.                                                                                                                    
23950-58-5.............  Pronamide........          21               440                 6                21               440                 6        
1120-71-4..............  Propane sultone,        (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
                          1,3-.                                                                                                                         
107-10-8...............  Propylamine, n-..           0.16             20                 0.11              0.16             20                 0.11     
51-52-5................  Propylthiouracil.           0.12          (\1\)                 6                 0.12          (\1\)                 6        
107-19-7...............  Propyn-1-ol,2-...          39             37000                15                39             37000                15        
129-00-0...............  Pyrene...........          54             16000                 2                54             16000                 2        
110-86-1...............  Pyridine.........           0.16            810                 0.06              0.16            810                 0.06     
50-55-5................  Reserpine........           0.16             20                 0.11              0.16             20                 0.11     
108-46-3...............  Resorcinol.......       (\1\)             (\1\)                 0.54          (\1\)             (\1\)                 0.48     
81-07-2................  Saccharin and           (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
                          salts.                                                                                                                        
94-59-7................  Safrole..........           0.0035           11             (\1\)                 0.0035           11             (\1\)        
7782-49-2..............  Selenium.........           0.23          (\1\)                 0.089             0.93          (\1\)                 0.36     
7440-22-4..............  Silver...........         200             (\1\)          ................       200             (\1\)          ................
18883-66-4.............  Streptozotocin...       (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
57-24-9................  Strychnine.......           0.045         (\1\)                 0.016             0.045         (\1\)                 0.016    
100-42-5...............  Stryene..........           0.91         630000                 0.22             64            630000                15        
18496-25-8.............  Sulfide..........  ..................  ................  ................  ................  ................  ................
1746-01-6..............  TCDD,2,3,7,8-....       (\1\)                 8.000E-06         5.400E-07     (\1\)                 8.000E-06     (\1\)        
95-94-3................  Tetrachlorobenzen           0.23            170                 0.032             0.23            170                 0.032    
                          e, 1,2,4,5-.                                                                                                                  
630-20-6...............  Tetrachloroethane           0.024           130                 0.0078            0.024           130                 0.0078   
                          , 1,1,1,2-.                                                                                                                   
79-34-5................  Tetrachloroethane           0.0037           29                 0.0077            0.0037           29                 0.0077   
                          , 1,1,2,2-.                                                                                                                   
127-18-4...............  Tetrachloroethyle           0.026         13000                 0.0085            2             13000                 0.68     
                          ne.                                                                                                                           
58-90-2................  Tetrachlorophenol           2              6200                 0.58              2              6200                 0.58     
                          , 2,3,4,6-.                                                                                                                   
107-49-3...............  Tetraethylpyropho       (\1\)              6900             (\1\)             (\1\)              6900           ( \1\ )        
                          sphate.                                                                                                                       
3689-24-5..............  Tetraethyldithiop           0.23              3          ................         0.23              3          ................
                          yrophosphate.                                                                                                                 
7440-28-0..............  Thallium (l).....           0.035             5                 0.014             0.05              5                 0.019    
62-55-5................  Thioacetamide....       (\1\)             (\1\)             (\1\)             (\1\)             (\1\)           ( \1\ )        
39196-18-4.............  Thiofanox........           0.12          (\1\)                 6                 0.12          (\1\)                 6        
108-98-5...............  Thiophenol.......           0.12              2                 6                 0.12              2                 6        
79-19-6................  Thiosemicarbazide       (\1\)             (\1\)          (\1\)(\1\)           (\1\)             (\1\)             (\1\)        
62-56-6................  Thiourea.........       (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
137-26-8...............  Thiram...........       (\1\)             (\1\)                 0.54          (\1\)             (\1\)                 0.48     
7440-31-5..............  Tin..............       (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
108-88-3...............  Toluene..........           6            180000                 2                30            180000                13        
584-84-9...............  Toluene                 (\1\)                20             (\1\)             (\1\)                20             (\1\)        
                          diisocyanate.                                                                                                                 
95-80-7................  Toluenediamine,2,       (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
                          4-.                                                                                                                           
823-40-5...............  Toluenediamine,2,           0.16             20                 0.11              0.16             20                 0.11     
                          6-.                                                                                                                           
496-72-0...............  Toluenediamine,3,           0.16             20                 0.11              0.16             20                 0.11     
                          4-.                                                                                                                           
636-21-5...............  Toluidine                   0.16             20                 0.11              0.16             20                 0.11     
                          hydrochloride, o-                                                                                                             
                          .                                                                                                                             
95-53-4................  Toluidine, o-....       (\1\)                 2             (\1\)             (\1\)                 2             (\1\)        
106-49-0...............  Toluidine, p-....       (\1\)                 0.13          (\1\)             (\1\)                 0.13          (\1\)        
8001-35-2..............  Toxaphene........       (\1\)             (\1\)                 6             (\1\)             (\1\)                 0.11     
76-13-1................  Trichloro-1,2,2-            0.77       ................         0.17           2200          ................      2400        
                          trifluoroethane,                                                                                                              
                          1,1,2-.                                                                                                                       
                                                                                                                                                        

[[Page 66451]]
                                                                                                                                                        
120-82-1...............  Trichlorobenzene,           0.69           3500                 1                 0.69           3500                 1        
                          1,2,4-.                                                                                                                       
72-55-6................  Trichloroethane,           74             48000                 0.054            74             48000                 0.054    
                          1,1,1-.                                                                                                                       
79-00-5................  Trichloroethane,            0.012            11                 0.009             0.007            11                 0.0018   
                          1,1,2-.                                                                                                                       
79-01-6................  Trichloroethylene           0.024           570                 0.008             0.038           570                 0.013    
75-69-4................  Trichlorofluorome          48             26000                16                48             26000                16        
                          thane.                                                                                                                        
75-70-7................  Trichloromethanet       (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
                          hiol.                                                                                                                         
95-95-4................  Trichlorophenol,           18             12000                 4                18             12000                 4        
                          2,4,5-.                                                                                                                       
88-06-2................  Trichlorophenol,            0.054           120                 0.015             0.054           120                 0.015    
                          2,4,6-.                                                                                                                       
93-76-5................  Trichlorophenoxya           2                63                 0.64              2                63                 0.64     
                          cetic acid,                                                                                                                   
                          2,4,5- (245-T).                                                                                                               
93-72-1................  Trichlorophenoxyp           0.21              6                 0.08              1                 6                 0.48     
                          ropionic acid,                                                                                                                
                          2,4,5-(Silvex).                                                                                                               
96-18-4................  Trichloropropane,           1               870                 0.34              1               870                 0.34     
                          1,2,3-.                                                                                                                       
99-35-4................  Trinitrobenzene,            0.0078            0.44              0.003             0.0078            0.44              0.003    
                          sym-.                                                                                                                         
126-72-7...............  Tris (2,3-              (\1\)                 0.36          (\1\)             (\1\)                 0.36          (\1\)        
                          dibromopropyl)                                                                                                                
                          phosphate.                                                                                                                    
52-24-4................  Tris(1-                 (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
                          azridinyl)phosph                                                                                                              
                          ine sulfide.                                                                                                                  
72-57-1................  Trypan blue......       (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
66-75-1................  Uracil mustard...       (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
7440-62-2..............  Vanadium.........          10               250                 4                10               250                 4        
108-05-4...............  Vinyl acetate....          15              6900                11                15              6900                11        
75-01-4................  Vinyl chloride...           0.002             1                 0.003         (\1\)                 1             (\1\)        
81-81-2................  Warfarin.........       (\1\)             (\1\)                 0.54          (\1\)             (\1\)                 0.48     
1330-20-7..............  Xylenes (total)..          22            170000                21                22            170000               150        
7440-66-6..............  Zinc.............          99               320                38                99               320                38        
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ See Table B.                                                                                                                                        



                                                        Table B.--Quantitation-Based Exit Levels                                                        
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                              MCL benchmark option                                Toxicity benchmark option             
                                             -----------------------------------------------------------------------------------------------------------
         CAS No.                 Name            Wastewater                Nonwastewater               Wastewater                Nonwastewater          
                                             -----------------------------------------------------------------------------------------------------------
                                                Totals (mg/l)    Totals (mg/kg)     Leach (mg/l)      Totals (mg/l)    Totals (mg/kg)     Leach (mg/l)  
--------------------------------------------------------------------------------------------------------------------------------------------------------
208-96-8................  Acenaphthylene....         0.02       ................         0.02              0.02       ................         0.02     
75-36-5.................  Acetyl chloride...     (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
591-08-2................  Acetyl-2-thiourea,         1                70          ................         1                70          ................
                           1-.                                                                                                                          
53-96-3.................  Acetylaminofluoren  ................  ................         0.02       ................  ................         0.02     
                           e, 2-.                                                                                                                       
107-02-8................  Acrolein..........         0.013      ................  ................         0.013      ................  ................
79-06-1.................  Acrylamide........         0.01              0.1               0.01              0.01              0.1               0.01     
107-13-1................  Acrylonitrile.....         0.008      ................         0.008             0.008      ................         0.008    
1402-68-2...............  Aflatoxins........     (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
116-06-3................  Aldicarb..........         0.05              1          ................         0.05              1          ................
309-00-2................  Aldrin............         0.000034          0.0006            0.000034          0.000034          0.0006            0.000034 
107-18-6................  Allyl alcohol.....     (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
92-67-1.................  Aminobiphenyl, 4-.  ................  ................         0.02       ................  ................         0.02     
2763-96-4...............  Aminomethyl-3-         (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
                           isoxazolol, 5-.                                                                                                              
504-24-5................  Aminopyridine, 4-.     (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
61-82-5.................  Amitrole..........     (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
120-12-7................  Anthracene........         0.007      ................         0.007             0.007      ................         0.007    
7440-38-2...............  Arsenic...........  ................         0.3        ................         0.0005            0.3               0.0005   
2465-27-2...............  Auramine..........     (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
115-02-6................  Azaserine.........     (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
92-87-5.................  Benzidine.........         0.0025            0.042             0.0025            0.0025            0.042             0.0025   
98-07-7.................  Benzotrichloride..     (\1\)          ................     (\1\)             (\1\)          ................     (\1\)        
50-32-8.................  Benzo(a)pyrene....  ................  ................  ................  ................  ................         0.000023 
205-82-3................  Benzo(j)fluor-      ................  ................  ................  ................  ................         0.0002   
                           anthene.                                                                                                                     
207-08-9................  Benzo(k)-           ................  ................  ................  ................  ................         0.0002   
                           fluoranthene.                                                                                                                
191-24-2................  Benzo[g,h,i]-       ................  ................  ................  ................  ................         0.0008   
                           perylene.                                                                                                                    
56-55-3.................  Benz(a)anth-        ................  ................         0.000013   ................  ................         0.000013 
                           racene.                                                                                                                      
225-51-4................  Benz[c]acri- dine.  ................  ................  ................  ................  ................         0.0005   
7440-41-7...............  Beryllium.........  ................         0.1        ................  ................         0.1        ................
542-88-1................  Bis(chloro-            (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
                           methyl) ether.                                                                                                               
357-57-3................  Brucine...........        20             (\1\)                20                20             (\1\)                20        
86-74-8.................  Carbazole.........      (\1\             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
353-50-4................  Carbon oxyfluoride     (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        

[[Page 66452]]
                                                                                                                                                        
75-87-6.................  Chloral...........     (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
305-03-3................  Chlorambucil......     (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
57-74-9.................  Chlordane.........         0.00004    ................  ................         0.00004    ................  ................
494-03-1................  Chlornaphazin.....     (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
107-20-0................  Chloroacetaldehyde      (\1\             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
110-75-8................  Chloroethyl vinyl      (\1\)          ................     (\1\)             (\1\)          ................     (\1\)        
                           ether, 2-.                                                                                                                   
107-30-2................  Chloromethyl           (\1\)          ................     (\1\)             (\1\)          ................     (\1\)        
                           methyl ether.                                                                                                                
5344-82-1...............  Chlorophenyl           (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
                           thiourea, 1-o-.                                                                                                              
542-76-7................  Chloropropionitril  ................  ................         0.1               0.1        ................         0.1      
                           e, 3-.                                                                                                                       
6358-53-8...............  Citrus red No. 2..     (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
7440-48-4...............  Cobalt............  ................  ................         0.5        ................  ................         0.5      
57-12-5.................  Cyanide...........         0.2        ................         0.2               0.2        ................         0.2      
14901-08-7..............  Cycasin...........     (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
108-94-1................  Cyclohexanone.....        10          ................        10                10          ................        10        
131-89-5................  Cyclohexyl-4,6-            0.1               7                 0.1               0.1               7                 0.1      
                           dinitrophenol, 2-.                                                                                                           
50-18-0.................  Cyclophosphamide..     (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
20830-81-3..............  Daunomycin........     (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
53-19-0.................  DDD (o,p\1\)......     (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
72-55-9.................  DDE...............         0.000058   ................  ................         0.000058   ................  ................
3424-82-6...............  DDE (o,p\1\)......     (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
50-29-3.................  DDT...............         0.000081   ................  ................         0.000081   ................  ................
789-02-6................  DDT (o,p\1\)......     (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
192-65-4................  Dibenzo[a,e]-       ................  ................  ................  ................  ................         0.001    
                           pyrene.                                                                                                                      
189-64-0................  Dibenzo[a,h]-       ................  ................  ................  ................  ................         0.0002   
                           pyrene.                                                                                                                      
189-55-9................  Dibenzo(a,i)pyrene  ................  ................  ................  ................  ................         0.0002   
194-59-2................  Dibenzo(c,g)car-           0.01       ................         0.01              0.01       ................         0.01     
                           bazole, 7H-.                                                                                                                 
226-36-8................  Dibenz(a,h)acri-    ................  ................  ................  ................  ................         0.0002   
                           dine.                                                                                                                        
53-70-3.................  Dibenz(a,h)ant-            0.00003           0.084             0.00003           0.00003           0.084             0.00003  
                           hracene.                                                                                                                     
224-42-0................  Dibenz(a,j)acridin  ................  ................  ................  ................  ................         0.001    
                           e.                                                                                                                           
96-12-8.................  Dibromo-3-          ................  ................  ................  ................  ................         0.00026  
                           chloropropane,                                                                                                               
                           1,2-.                                                                                                                        
91-94-1.................  Dichlorobenzidine,  ................         0.12              0.0024     ................         0.012             0.0024   
                           3,3\1\-.                                                                                                                     
542-75-6................  Dichloropropene,    ................  ................         0.0009     ................  ................         0.0009   
                           1,3-.                                                                                                                        
311-45-5................  Diethyl-p-             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
                           nitrophenyl                                                                                                                  
                           phosphate.                                                                                                                   
56-53-1.................  Diethylstilbestrol         0.0078            1                 0.0078            0.0078            1                 0.0078   
77-78-1.................  Dimethyl sulfate..     (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
60-11-7.................  Dimethylaminoazobe  ................  ................         0.01       ................  ................         0.01     
                           nzene, p-.                                                                                                                   
119-93-7................  Dimethylbenzidine,         0.0033            0.7               0.0033            0.0033            0.7               0.0033   
                           3,3\1\-.                                                                                                                     
57-97-6.................  Dimethylbenz-              0.00037           0.039             0.00037           0.00037           0.039             0.00037  
                           (a)anthracene,                                                                                                               
                           7,12-.                                                                                                                       
79-44-7.................  Dimethylcarbamoyl      (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
                           chloride.                                                                                                                    
119-90-4................  Dimethyoxybenzidin  ................         7          ................  ................         7          ................
                           e, 3,3\1\-.                                                                                                                  
100-25-4................  Dinitrobenzene,            0.04              3                 0.04              0.04              3                 0.4      
                           1,4-.                                                                                                                        
534-52-1................  Dinitro-o-cresol,          0.05              3                 0.05              0.05              3                 0.05     
                           4,6-.                                                                                                                        
541-53-7................  Dithiobiuret......     (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
                          D, salts, esters,   ................         0.2        ................  ................         0.2        ................
                           2,4-.                                                                                                                        
145-73-3................  Endothall.........         0.1           (\1\)          ................         0.1           (\1\)          ................
51-43-4.................  Epinephrine.......     (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
62-50-0.................  Ethyl               ................         0.018      ................  ................         0.018      ................
                           methanesulfonate.                                                                                                            
106-93-4................  Ethylene Dibromide  ................  ................  ................  ................  ................         0.00006  
96-45-7.................  Ethylene thiourea.     (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
151-56-4................  Ethyleneimine          (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
                           (aziridine).                                                                                                                 
52-85-7.................  Famphur...........         0.02              1          ................         0.02              1          ................
640-19-7................  Fluoracetamide, 2-     (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
62-74-8.................  Fluoracetic acid,      (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
                           sodium salt.                                                                                                                 
16984-48-8..............  Fluoride..........  ................  ................  ................  ................  ................  ................
50-00-0.................  Formaldehyde......         0.023      ................  ................         0.023      ................  ................
765-34-4................  Glycidylaldehyde..     (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
76-44-8.................  Heptachlor........         0.00004    ................  ................         0.00004    ................  ................

[[Page 66453]]
                                                                                                                                                        
118-74-1................  Hexachlorobenzene.         0.0016            0.072      ................         0.0016            0.072             0.0016   
70-30-4.................  Hexachlorophene...         0.21              2                 0.21              0.21              2                 0.21     
757-58-4................  Hexaethyl              (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
                           tetraphosphate.                                                                                                              
302-01-2................  Hydrazine.........     (\1\)          ................     (\1\)             (\1\)          ................     (\1\)        
193-39-5................  Indeno(1,2,3-cd)    ................  ................         0.000043   ................  ................         0.000043 
                           pyrene.                                                                                                                      
465-73-6................  Isodrin...........         0.02              1          ................         0.02              1          ................
143-50-0................  Kepone............         0.016             0.097             0.016             0.016             0.097             0.016    
303-43-4................  Lasiocarpine......     (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
108-31-6................  Maleic anhydride..     (\1\)          ................     (\1\)             (\1\)          ................     (\1\)        
148-82-3................  Melphalan.........     (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
126-98-7................  Methacrylonitrile.  ................  ................         0.009      ................  ................         0.009    
74-93-1.................  Methanethiol......     (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
16752-77-5..............  Methomyl..........         0.05              3          ................         0.05              3          ................
1338-23-4...............  Methyl ethyl           (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
                           ketone peroxide.                                                                                                             
60-34-4.................  Methyl hydrazine..     (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
91-57-6.................  Methyl                     0.01       ................         0.01              0.01       ................         0.01     
                           naphthalene, 2-.                                                                                                             
75-55-8.................  Methylaziridine, 2-    (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
                           .                                                                                                                            
56-49-5.................  Methylcholanthrene         0.01              0.046             0.01              0.01              0.046             0.01     
                           , 3-.                                                                                                                        
101-14-4................  Methylenebis,          (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
                           4,4\1\-(2-                                                                                                                   
                           chloroaniline).                                                                                                              
70-25-7.................  Methyl-nitro-          (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
                           nitrosoguanidine                                                                                                             
                           (MNNG).                                                                                                                      
56-04-2.................  Methylthiouracil..     (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
50-07-7.................  Mitomycin C.......     (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
86-88-4.................  Naphthyl-2-            (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
                           thiourea, 1-.                                                                                                                
88-74-4.................  Nitroaniline, 2-..         0.05       ................         0.05              0.05       ................         0.05     
99-09-2.................  Nitroaniline, 3-..         0.05       ................         0.05              0.05       ................         0.05     
100-01-6................  Nitroaniline, 4-..  ................  ................         0.02       ................  ................         0.02     
55-86-7.................  Nitrogen mustard..     (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
51-75-2.................  Nitrogen mustard       (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
                           hydrochloride                                                                                                                
                           salt.                                                                                                                        
126-85-2................  Nitrogen mustard N-    (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
                           Oxide.                                                                                                                       
302-70-5................  Nitrogen mustard N-    (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
                           Oxide, HCI salt.                                                                                                             
55-63-0.................  Nitroglycerine....     (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
99-55-8.................  Nitro-o-toluidine,  ................  ................         0.01       ................  ................         0.01     
                           5-.                                                                                                                          
88-75-5.................  Nitrophenol, 2-...  ................  ................         0.01       ................  ................         0.01     
100-02-7................  Nitrophenol, 4-...         0.05              3                 0.05              0.05              3                 0.05     
79-46-9.................  Nitropropane, 2-..         0.0058     ................  ................         0.0058     ................  ................
55-18-5.................  Nitrosodiethylamin         0.002             1                 0.002             0.002             1                 0.002    
                           e.                                                                                                                           
62-75-9.................  Nitrosodimethylami         0.0006            0.074             0.0006            0.0006            0.074             0.0006   
                           ne.                                                                                                                          
924-16-3................  Nitrosodi-n-               0.06       ................         0.06              0.06       ................         0.06     
                           butylamine.                                                                                                                  
10595-95-6..............  Nitrosomethylethyl         0.028             0.016             0.028             0.028             0.016             0.028    
                           amine.                                                                                                                       
1116-54-7...............  N-                         0.01              0.7               0.01              0.01              0.7               0.01     
                           Nitrosodiethanola                                                                                                            
                           mine.                                                                                                                        
621-64-7................  N-Nitrosodi-n-             0.026      ................         0.026             0.026      ................         0.026    
                           propylamine.                                                                                                                 
86-30-6.................  N-                  ................  ................         0.05       ................  ................         0.05     
                           Nitrosodiphenylam                                                                                                            
                           ine.                                                                                                                         
4549-40-0...............  N-Nitrosomethyl        (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
                           vinyl amine.                                                                                                                 
759-73-9................  N-Nitroso-N-           (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
                           ethylurea.                                                                                                                   
615-53-2................  N-Nitroso-N-           (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
                           methylurethane.                                                                                                              
16543-55-8..............  N-                     (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
                           Nitrosonornicotin                                                                                                            
                           e.                                                                                                                           
100-75-4................  N-                         0.0014            0.033             0.0014            0.0014            0.033             0.0014   
                           Nitrosopiperidine.                                                                                                           
930-55-2................  N-                         0.0047     ................         0.0047            0.0047     ................         0.0047   
                           Nitrosopyrrolidin                                                                                                            
                           e.                                                                                                                           
13256-22-9..............  N-Nitrososarcosine     (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
103-85-5................  N-Phenylthiourea..     (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
1615-80-1...............  N,N-                   (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
                           Diethylhydrazine.                                                                                                            
20816-12-0..............  Osmium tetroxide..         3               200                 3                 3               200                 3        
126-68-1................  O,O,O-Triethyl      ................         3          ................  ................         3          ................
                           phosphorothioate.                                                                                                            
82-68-8.................  Pentachloronitrobe  ................  ................         0.02       ................  ................         0.02     
                           nzene (PCNB).                                                                                                                
85-01-8.................  Phenanthrene......         0.006      ................         0.006             0.006      ................         0.006    
62-38-4.................  Phenyl mercuric        (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
                           acetate.                                                                                                                     
                          Phosphorodithiolic     (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
                           acid,                                                                                                                        
                           dimethylethyleste                                                                                                            
                           r.                                                                                                                           
298-06-6................  Phosphorodithioic      (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
                           acid, o-o-diethyl                                                                                                            
                           ester.                                                                                                                       
3288-58-2...............  Phosphorodithioic      (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
                           acid, o-o-diethyl-                                                                                                           
                           s-methyl.                                                                                                                    
2953-29-9...............  Phosphorodithioic      (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
                           acid, trimethyl                                                                                                              
                           ester.                                                                                                                       
85-44-9.................  Phthalic anhydride     (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
1336-36-3...............  Polychlorinated            0.0005            0.04       ................         0.0005            0.04              0.0005   
                           biphenyls.                                                                                                                   
1120-71-4...............  Propane sultone,       (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
                           1,3-.                                                                                                                        
51-52-5.................  Propylthiouracil..  ................         7          ................         7          ................                  
108-46-3................  Resorcinol........         0.1               7          ................         0.1               7          ................
81-07-2.................  Saccharin and          (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
                           salts.                                                                                                                       

[[Page 66454]]
                                                                                                                                                        
94-59-7.................  Safrole...........  ................  ................         0.0021     ................  ................         0.0021   
94-59-7.................  Safrole...........  ................  ................         0.0021     ................  ................         0.0021   
7782-49-2...............  Selenium..........  ................         5          ................  ................         5          ................
7440-22-4...............  Silver............  ................         0.3        ................  ................         0.3        ................
18883-66-4..............  Streptozotocin....     (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
57-24-9.................  Strychnine........  ................         3          ................  ................         3          ................
1746-01-6...............  TCDD, 2,3,7,8-....         1.000E-08  ................  ................         1.000E-08  ................         1.000E-08
107-49-3................  Tetraethyl             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
                           pyrophosphate.                                                                                                               
62-55-5.................  Thioacetamide.....         1             (\1\)                 1                 1             (\1\)                 1        
39196-18-4..............  Thiofanox.........  ................         3          ................  ................         3          ................
79-19-6.................  Thiosemicarbazide.     (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
62-56-6.................  Thiourea..........     (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
137-26-8................  Thiram............         0.05              3          ................         0.05              3          ................
7440-31-5...............  Tin...............         8               500                 8                 8               500                 8        
584-84-9................  Toluene                (\1\)          ................     (\1\)             (\1\)          ................  ................
                           diisocyanate.                                                                                                                
95-80-7.................  Toluenediamine,            0.013             1                 0.013             0.013             1                 0.013    
                           2,4-.                                                                                                                        
95-53-4.................  Toluidine, o-.....         0.012      ................         0.012             0.012      ................         0.012    
106-49-0................  Toluidine, p-.....         0.017      ................         0.017             0.017      ................         0.017    
8001-35-2...............  Toxaphene.........         0.0013            0.03       ................         0.0013            0.03       ................
75-70-7.................  Trichloromethaneth     (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
                           iol.                                                                                                                         
126-72-7................  Tris (2,3-                 0.025      ................         0.025             0.025      ................         0.025    
                           dibromopropyl)                                                                                                               
                           phosphate.                                                                                                                   
52-24-4.................  Tris(1-azridinyl)      (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
                           phosphine sulfide.                                                                                                           
72-57-1.................  Trypan blue.......     (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
66-75-1.................  Uracil mustard....     (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
75-01-4.................  Vinyl chloride....  ................  ................  ................         0.00017    ................         0.00017  
81-81-2.................  Warfarin..........         0.05              3          ................         0.05              3          ................
--------------------------------------------------------------------------------------------------------------------------------------------------------



                                                                                                                                                        

[[Page 66455]]
    8. Appendix XI is added to read as follows:                                                                                                         
Appendix XI                                                                                                                                             
                                                                                                                                                        



                                          Table A.--Modeled or Extrapolated Risk-Based Conditional Exit Levels                                          
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                              MCL benchmark option                                Toxicity benchmark option             
                                             -----------------------------------------------------------------------------------------------------------
       CAS No.                  Name             Wastewater                Nonwastewater               Wastewater                Nonwastewater          
                                             -----------------------------------------------------------------------------------------------------------
                                                Totals (mg/l)    Totals (mg/kg)     Leach (mg/l)      Totals (mg/l)    Totals (mg/kg)     Leach (mg/l)  
--------------------------------------------------------------------------------------------------------------------------------------------------------
83-32-9..............  Acenaphthene.........        31             63000                13                31             63000                13        
208-96-8.............  Acenaphthylene.......     (\1\)                 4             (\1\)             (\1\)                 4             (\1\)        
67-64-1..............  Acetone..............        16             39000                21                16             39000                21        
75-05-8..............  Acetonitrile.........         0.78           2200                 1                 0.78           2200                 1        
98-86-2..............  Acetophenone.........        17             75000                22                17             75000                22        
75-36-5..............  Acetyl chloride......     (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
591-08-2.............  Acetyl-2-thiourea, 1-     (\1\)               590                24             (\1\)               590                24        
53-96-3..............  Acetylaminofluorne, 2-        0.028            88                 0.038             0.028            88                 0.038    
                        .                                                                                                                               
107-02-8.............  Acrolein.............     (\1\)                11          ................     (\1\)                11          ................
79-06-1..............  Acrylamide...........     (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
107-13-1.............  Acrylonitrile........     (\1\)                 2             (\1\)             (\1\)                 2             (\1\)        
1402-68-2............  Aflatoxins...........     (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
116-06-3.............  Aldicarb.............     (\1\)                 6                 4             (\1\)                 6                 3        
309-00-2.............  Aldrin...............     (\1\)                 0.0045        (\1\)             (\1\)                 0.0045        (\1\)        
107-18-6.............  Allyl alcohol........     (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
107-05-1.............  Allyl chloride.......         0.074           260          ................         0.074           260          ................
92-67-1..............  Aminobiphenyl, 4-....         0.028            88                 0.038             0.028            88                 0.038    
2763-96-4............  Aminomethyl-3-            (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
                        isoxazolol, 5-.                                                                                                                 
504-24-5.............  Aminopyridine, 4-....     (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
61-82-5..............  Amitrole.............     (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
62-53-3..............  Aniline..............         0.053           170                 0.072             0.053           170                 0.072    
120-12-7.............  Anthracene...........     (\1\)                 4             (\1\)             (\1\)                 4             (\1\)        
7440-36-0............  Antimony.............         0.14             85                 0.18              0.14             85                 0.18     
140-57-8.............  Aramite..............        15              6900                37                15              6900                37        
7440-38-2............  Arsenic..............         0.38              0.53              0.52          (\1\)                 0.53              0.00052  
2465-27-2............  Auramine.............     (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
115-02-6.............  Azaserine............     (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
7440-39-3............  Barium...............        28             34000                38                33             34000                45        
71-43-2..............  Benzene..............         0.021           250                 0.039             0.018           250                 0.023    
92-87-5..............  Benzidine............     (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
106-51-4.............  Benzoquinone, p-.....        15              6900                37                15              6900                37        
98-07-7..............  Benzotrichloride.....     (\1\)              1200             (\1\)             (\1\)              1200             (\1\)        
50-32-8..............  Benzo(a)pyrene.......         0.0023            0.23              0.0036            0.0023            0.23          (\1\)        
205-99-2.............  Benzo(b) fluoranthene         0.00081           4                 0.000066          0.00081           4                 0.000066 
205-82-3.............  Benzo(j) fluoranthene         0.0029            4                 0.0012            0.0029            4             (\1\)        
207-08-9.............  Benzo(k) fluoranthene         0.0029            4                 0.0012            0.0029            4             (\1\)        
191-24-2.............  Benzo[g, h,                   0.0029            4                 0.0012            0.0029            4             (\1\)        
                        i]perylene.                                                                                                                     
100-51-6.............  Benzyl alcohol.......        39            130000                53                39            130000                53        
100-44-7.............  Benzyl chloride......         1                81                50                 1                81                50        
56-55-3..............  Benz(a) anthracene...         0.00072           0.1           (\1\)                 0.00072           0.1           (\1\)        
225-51-4.............  Benz[c] acridine.....         0.0029            4                 0.0012            0.0029            4             (\1\)        
7440-41-7............  Beryllium............         0.00083           0.22              0.0011            0.00083           0.22              0.0011   
39638-32-9...........  Bis (2-                       0.007            97                 0.0088            0.007            97                 0.0088   
                        chloroisopropyl)                                                                                                                
                        ether.                                                                                                                          
111-44-4.............  Bis(2-chlore-                 0.00065           1                 0.002             0.00065           1                 0.002    
                        thyl)ether.                                                                                                                     
117-81-7.............  Bis(2-ethy-                   0.00044         740                 0.11              0.00044         740                 0.0011   
                        lexyl)phthalate.                                                                                                                
542-88-1.............  Bis(chlor-                (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
                        omethyl)ether.                                                                                                                  
598-31-2.............  Bromoacetone.........         0.024           140                 0.054             0.023           140                 0.053    
75-27-4..............  Bromodich-                    0.0085          240                 0.011             0.0085          240                 0.011    
                        loromethane.                                                                                                                    
75-25-2..............  Bromoform                     0.064          1600                 0.081             0.064          1600                 0.081    
                        (Tribromomethane).                                                                                                              
101-55-3.............  Bromophenyl phenyl            0.024           140                 0.054             0.023           140                 0.053    
                        ether, 4-.                                                                                                                      
357-57-3.............  Brucine..............     (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
71-36-3..............  Butanol..............        16             41000                21                16             41000                21        
88-85-7..............  Butyl-4,6-                    0.034          6000                 0.043             0.19           6000                 0.24     
                        dinitrophenol, 2-sec-                                                                                                           
                         (Dinoseb).                                                                                                                     
85-68-7..............  Butylbenzyl-                240                87                67               240                87               67         
                        phthalate.                                                                                                                      

[[Page 66456]]
                                                                                                                                                        
7440-43-9............  Cadmium..............         0.038           110                 0.051             0.24            110                 0.32     
86-74-8..............  Carbazole............     (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
75-15-0..............  Carbon disulfide.....         0.74           3800                24                 0.74           3800                24        
353-50-4.............  Carbon oxyfluoride...     (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
56-23-5..............  Carbon tetrachloride.         0.012           130                 0.055             0.012           130                 0.0077   
75-87-6..............  Chloral..............     (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
305-03-3.............  Chlorambucil.........     (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
57-74-9..............  Chlordane............     (\1\)                 0.19              0.036         (\1\)                 0.19              0.00016  
494-03-1.............  Chlornaphazin........     (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
126-99-8.............  Chloro-1,3-butabiene,         0.52           1700          ................         0.52           1700          ................
                        2-(Chloroprene).                                                                                                                
107-20-0.............  Chloroacetaldehyde...     (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
106-47-8.............  Chlororoaniline, p-..         0.42           5800                 0.56              0.42           5800                 0.56     
108-90-7.............  Chlorobenzene........         0.68          41000                 0.81              2             41000                 6        
510-15-6.............  Chlorobenzilate......         0.054            14                 0.029             0.054            14                 0.029    
124-48-1.............  Chlorodibromomethane.         0.0066          200                 0.0079            0.0066          200                 0.0079   
75-00-3..............  Chloroethane (ethyl           0.024           140                 0.054             0.023           140                 0.053    
                        chloride).                                                                                                                      
110-75-8.............  Chloroethyl vinyl         (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
                        ether, 2-.                                                                                                                      
67-66-3..............  Chloroform...........         0.0076           76                 0.075             0.0076           76                 0.075    
59-50-7..............  Chloro-m-cresol, p-..         0.27           1200                 0.068             0.081          1200                 0.06     
107-30-2.............  Chloromethyl methyl       (\1\)               140             (\1\)             (\1\)               140             (\1\)        
                        ether.                                                                                                                          
91-58-7..............  Chloronaphthalene, 2-         0.27           1200                 0.068             0.081          1200                 0.06     
95-57-8..............  Chlorophenol, 2-.....         0.9            8500                 1                 0.9            8500                 1        
7005-72-3............  Chlorophenyl phenyl           0.024           140                 0.054             0.023           140                 0.053    
                        ether, 4-.                                                                                                                      
5344-82-1............  Chlorophenyl              (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
                        thiourea, 1-o-.                                                                                                                 
542-76-7.............  Chloropropionitrile,          0.27           1200             (\1\)             (\1\)              1200             (\1\)        
                        3-.                                                                                                                             
7440-47-3............  Chromium.............         0.62             16                 0.31              1                16                 2        
218-01-9.............  Chrysene.............         0.1              35                 0.0012            0.1              35                 0.0012   
6358-53-8............  Citrus red No. 2.....     (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
7440-48-4............  Cobalt...............         0.62            110             (\1\)                 1               110                 1        
7440-50-8............  Copper...............       670               950              3800               670               950              3800        
108-39-4.............  Cresol, m-...........         8             30000                11                 8             30000                11        
95-48-7..............  Cresol, o-...........         8             46000                11                 8             46000                11        
106-44-5.............  Cresol, p-...........         0.84           2900                 1                 0.84           2900                 1        
4170-30-3............  Crotonaldehyde.......         8             38000                22                 8             38000                22        
57-12-5..............  Cyanide..............     (\1\)                51                 0.37          (\1\)                51                 0.37     
14901-08-7...........  Cycasin..............     (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
108-94-1.............  Cyclohexanone........     (\1\)             38000                22             (\1\)             38000                22        
131-89-5.............  Cyclohexyl-4,6-           (\1\)                42             (\1\)             (\1\)                42             (\1\)        
                        dinitrophenol, 2-.                                                                                                              
50-18-0..............  Cyclophosphamide.....     (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
20830-81-3...........  Daunomycin...........     (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
72-54-8..............  DDD..................         0.00013           0.26           6800                 0.00013           0.26           6800        
53-19-0..............  DDD (o,p')...........     (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
72-55-9..............  DDE..................     (\1\)                 0.033             0.000062      (\1\)                 0.033             0.000062 
3424-82-6............  DDE (o,p')...........     (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
50-29-3..............  DDT..................     (\1\)                 0.11              0.0054        (\1\)                 0.11              0.0054   
789-02-6.............  DDT (o,p')...........     (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
2303-16-4............  Diallate.............         0.26              7                11                 0.26              7                11        
132-64-9.............  Dibenzofuran.........         8             38000                 9                 8             38000                11        
192-65-4.............  Dibenzo- [a,e]pyrene.         0.0029            4                 0.0012            0.0029            4             (\1\)        
189-64-0.............  Dibenzo- [a,h]pyrene.         0.0029            4                 0.0012            0.0029            4             (\1\)        
189-55-9.............  Dibenzo- [a,i]pyrene.         0.0029            4                 0.0012            0.0029            4             (\1\)        
194-59-2.............  Dibenzo-                  (\1\)                 4             (\1\)             (\1\)                 4             (\1\)        
                        [c,g]carbazole, 7H-.                                                                                                            
226-36-8.............  Dibenz- (a,h)acridine         0.0029            4                 0.0012            0.0029            4             (\1\)        
53-70-3..............  Dibenz- (a,h)anth-        (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
                        racene.                                                                                                                         
244-42-0.............  Dibenz- [a,j]acridine         0.0029            4                 0.0012            0.0029            4             (\1\)        
96-12-8..............  Dibromo-3-chloropro-          0.0022            7                 0.0017            0.00066           7                 0.00052  
                        pane, 1,2-.                                                                                                                     
764-41-0.............  Dichloro-2-butene,            0.024           140                 0.054             0.023           140                 0.053    
                        1,4-.                                                                                                                           

[[Page 66457]]
                                                                                                                                                        
110-57-6.............  Dichloro-2-butene,            0.024           140                 0.054             0.023           140                 0.053    
                        trans-1,4-.                                                                                                                     
96-23-1..............  Dichloro-2-propanol,          0.27           1200                 0.068             0.081          1200                 0.06     
                        1,3-.                                                                                                                           
95-50-1..............  Dichlorobenzene, 1,2-         8            530000                 8                15            530000                32        
541-73-1.............  Dichlorobenzene, 1,3-         0.024           140                 0.054             0.023           140                 0.053    
106-46-7.............  Dichlorobenzene, 1,4-         1               650                 1                 0.056           650                 0.06     
91-94-1..............  Dichlorobenzidine,            0.0037            1                 0.0036            0.0037            1                 0.0036   
                        3,3'-.                                                                                                                          
75-71-8..............  Dichloro-                    15              8400                45                15              8400                45        
                        difluoromethane.                                                                                                                
75-34-3..............  Dichloroethane, 1,1-.         0.00016         110                 0.00021           0.00016         110                 0.00021  
107-06-2.............  Dichloroethane, 1,2-.         0.007            59                 0.011             0.00016          59                 0.00021  
75-35-4..............  Dichloroethy lene,            0.0035           20                 0.054             0.00059          20                 0.00077  
                        1,1-.                                                                                                                           
156-59-2.............  Dichlorethylene, cis-         0.29          46000                 0.39              2             46000                 2        
                        1,2-.                                                                                                                           
150-60-5.............  Dichlorethylene,              0.42         130000                 0.56              3            130000                 4        
                        trans-1,2-.                                                                                                                     
111-91-1.............  Dichloromethoxy               0.024           140                 0.054             0.023           140                 0.053    
                        ethane.                                                                                                                         
98-87-3..............  Dichloromethylbenzene         0.024           140                 0.054             0.023           140                 0.053    
                        (benzal chloride).                                                                                                              
120-83-2.............  Dichlorophenol, 2,4-.         0.62            770                 0.76              0.62            770                 0.76     
87-65-0..............  Dichlorophenol, 2,6-.         0.024           140                 0.054             0.023           140                 0.053    
94-75-7..............  Dichlorophenoxyacetic         0.27          12000                 0.37              2             12000                 2        
                        acid, 2,4- (2,4-D).                                                                                                             
78-87-5..............  Dichloropropane, 1,2-         0.12            180                 0.055             0.023           180                 0.011    
542-75-6.............  Dichloropropene, 1,3-         0.0028           68                 0.0038            0.0028           68                 0.0038   
10061-01-5...........  Dichloropropene, cis-         0.0049           65             10000                 0.0049           65             10000        
                        1,3-.                                                                                                                           
10061-02-6...........  Dichloropropene,              0.0049           62             10000                 0.0049           62             10000        
                        trans-1,3-.                                                                                                                     
60-57-1..............  Dieldrin.............         0.000059          0.048            36                 0.000059          0.048            36        
1464-53-5............  Diepoxybutane,               15              6900                37                15              6900                37        
                        1,2,3,4- (2,2'-                                                                                                                 
                        bioxirane).                                                                                                                     
84-66-2..............  Diethyl phthalate....       190             19000               220               190             19000               220        
311-45-5.............  Diethyl-p-nitrophenyl     (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
                        phosphate.                                                                                                                      
56-53-1..............  Diethylstilbestrol...     (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
94-58-6..............  Dihydrosafrole.......        15              6900                37                15              6900                37        
60-51-5..............  Dimethoate...........        29                 7                 4                29                 7                 4        
131-11-3.............  Dimethyl phthalate...        78                 3               110                78                 3               110        
77-78-1..............  Dimethyl sulfate.....     (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
60-11-7..............  Dimethyl- aminoazo-           0.028            88                 0.038             0.028            88                 0.038    
                        benzene, p-.                                                                                                                    
119-93-7.............  Dimethylbenzidine,        (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
                        3,3'-.                                                                                                                          
57-97-6..............  Dimethyl- benz(a)-        (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
                        anthracene, 7,12-.                                                                                                              
79-44-7..............  Dimethylcarbamoyl         (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
                        chloride.                                                                                                                       
122-09-8.............  Dimethyl- phenethyl-          0.16             51                 0.37              0.16             51                 0.37     
                        amine, alpha, alpha-.                                                                                                           
105-67-9.............  Dimethylphenol, 2,4-.         4             24000                 5                 4             24000                 5        
119-90-4.............  Dimethyoxy-                   0.034         (\1\)                 0.045             0.034         (\1\)                 0.045    
                        benzidine, 3,3'-.                                                                                                               
84-74-2..............  Di-n-butyl phthalate.       880             90000               100               230             90000                25        
99-65-0..............  Dinitrobenzene, 1,3-.         0.017            60                 0.022             0.017            60                 0.022    
100-25-4.............  Dinitrobenzene, 1,4-.     (\1\)                42             (\1\)             (\1\)                42             (\1\)        
534-52-1.............  Dinitro-o-cresol, 4,6-    (\1\)                42             (\1\)             (\1\)                42             (\1\)        
                        .                                                                                                                               
51-28-5..............  Dinitrophenol, 2,4-..         0.27            450                 0.37              0.27            450                 0.37     
121-14-2.............  Dinitrotoluene, 2,4-.         0.29           1400                 0.39              0.29           1400                 0.39     
606-20-2.............  Dinitrotoluene, 2,6-.         0.17            420                 0.22              0.17            420                 0.22     
117-84-0.............  Di-n-octyl phthalate.         0.002         21000                 0.1               0.002         21000                 0.1      
123-91-1.............  Dioxane, 1,4-........         0.042            71                 0.058             0.042            71                 0.058    
122-39-4.............  Diphenylamine........        15             12000                15                15             12000                15        
122-66-7.............  Diphenylhydrazine,            0.16             51                 0.37              0.16             51                 0.37     
                        1,2-.                                                                                                                           
298-04-4.............  Disulfoton...........         0.013            58               120                 0.013            58               120        
541-53-7.............  Dithiobiuret.........     (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
                       D, salts, esters, 2,4-        0.0069            6                 4                 0.0069            6                 3        
                        .                                                                                                                               
115-29-7.............  Endosulfan...........         6               150                 4                 6               150                 4        
959-98-8.............  Endosulfan I.........         0.0069            6                 4                 0.0069            6                 3        
33213-65-9...........  Endosulfan II........         0.0069            6                 4                 0.0069            6                 3        
1031-07-8............  Endosulfan sulfate...         0.0069            6                 4                 0.0069            6                 3        
145-73-3.............  Endothall............     (\1\)             (\1\)                 4             (\1\)             (\1\)                 3        
72-20-8..............  Endrin...............         0.073            27               880                 0.073            27               770        
7421-93-4............  Endrin Aldehyde......         0.0069            6                 4                 0.0069            6                 3        
53494-70-5...........  Endrin ketone........         0.0069            6                 4                 0.0069            6                 3        
106-89-8.............  Epichlorohydrin......         0.34             96             47000                 0.34             96             47000        
51-43-4..............  Epinephrine..........     (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
110-80-5.............  Ethoxyethanol, 2-....        15              6900                53                15              6900                53        
141-78-6.............  Ethyl acetate........       390            600000               510               390            600000               510        
51-79-6..............  Ethyl carbamate......        15              6900                37                15              6900                37        
107-12-0.............  Ethyl cyanide                 0.16             51                 0.37              0.16             51                 0.37     
                        (propionitrile).                                                                                                                
60-29-7..............  Ethyl ether..........        27            260000                37                27            260000                37        

[[Page 66458]]
                                                                                                                                                        
97-63-2..............  Ethyl methacrylate...        24            100000                27                24            100000                27        
62-50-0..............  Ethyl                         0.0055        (\1\)             99000                 0.0055        (\1\)             99000        
                        methanesulfonate.                                                                                                               
100-41-4.............  Ethylbenzene.........         8          ................         9                39          ................        42        
106-93-4.............  Ethylene Dibromide...         0.00093           0.06              0.0049            0.00036           0.06              0.000098 
75-21-8..............  Ethylene oxide.......        15              6900                37                15              6900                37        
96-45-7..............  Ethylene thiourea....     (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
151-56-4.............  Ethyleneimine             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
                        (aziridine).                                                                                                                    
52-85-7..............  Famphur..............     (\1\)                 6                 4             (\1\)                 6                 3        
640-19-7.............  Fluoracetamide, 2-...     (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
62-74-8..............  Fluoracetic acid,         (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
                        sodium salt.                                                                                                                    
206-44-0.............  Fluoranthene.........        28             21000                 2                28             21000                 2        
86-73-7..............  Fluorene.............        22             90000                 7                22             90000                 7        
16984-48-8...........  Fluoride.............  ................  ................  ................  ................  ................                  
50-00-0..............  Formaldehyde.........     (\1\)                54                37             (\1\)                54                37        
64-18-6..............  Formic Acid..........       270            680000               370               270            680000               370        
765-34-4.............  Glycidylaldehyde.....     (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
319-86-8.............  HCH, delta-..........         0.0069            6                 4                 0.0069            6                 3        
76-44-8..............  Heptachlor...........     (\1\)                 8          ................     (\1\)                 8          ................
1024-57-3............  Heptachlor epoxide...         0.00053           0.56           1900                 0.00053           0.56             10        
87-68-3..............  Hexachloro-1,3-               0.0079          290                 0.0069            0.0079          290                 0.0069   
                        butadiene.                                                                                                                      
118-74-1.............  Hexachlorobenzene....     (\1\)                 0.27              0.018         (\1\)                 0.27          (\1\)        
319-84-6.............  Hexachlorocyclohexane         0.00014           0.18              2                 0.00014           0.18              2        
                        , alpha- (alpha-BHC).                                                                                                           
319-85-7.............  Hexachlorocyclohexane         0.00044           0.64              0.0009            0.00044           0.64              0.0009   
                        , beta- (beta-BHC).                                                                                                             
58-89-9..............  Hexachlorocyclohexane         0.00078           0.75             26                 0.00078           0.75              9        
                        , gamma- (Lindane).                                                                                                             
77-47-4..............  Hexachlorocyclopentad         0.0052         1500          ................         0.0052         1500          ................
                        iene.                                                                                                                           
67-72-1..............  Hexachloroethane.....         0.049           890                 0.11              0.049           890                 0.11     
70-30-4..............  Hexachlorophene......     (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
1888-71-7............  Hexachloropropene....         0.27           1200                 0.068             0.081          1200                 0.06     
757-58-4.............  Hexaethyl                 (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
                        tetraphosphate.                                                                                                                 
591-78-6.............  Hexanone, 2-.........         8             38000                22                 8             38000                22        
302-01-2.............  Hydrazine............     (\1\)                51             (\1\)             (\1\)                51             (\1\)        
193-39-5.............  Indeno(1,2,3-cd)              0.0029            4             (\1\)                 0.0029            4             (\1\)        
                        pyrene.                                                                                                                         
74-88-4..............  Iodomethane..........         0.024           140                 0.054             0.023           140                 0.053    
78-83-1..............  Isobutyl alcohol.....        39            120000                53                39            120000                53        
465-73-6.............  Isodrin..............     (\1\)                 6                 4             (\1\)                 6                 3        
78-59-1..............  Isophorone...........         0.53           2000                 0.69              0.53           2000                 0.69     
120-58-1.............  Isosafrole...........        15              6900                37                15              6900                37        
143-50-0.............  Kepone...............     (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
303-43-4.............  Lasiocarpine.........     (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
7439-92-1............  Lead.................        30              1600                41                30              1600                41        
108-31-6.............  Maleic anhydride.....     (\1\)              6900             (\1\)             (\1\)              6900             (\1\)        
123-33-1.............  Maleic hydrazide.....         0.16             51                 0.37              0.16             51                 0.37     
109-77-3.............  Malononitrile........         0.16             51                 0.37              0.16             51                 0.37     
148-82-3.............  Melphalan............     (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
7439-97-6............  Mercury..............         0.06             39                 0.081             0.3              39                 0.4      
126-98-7.............  Methacrylonitrile....         0.016            72                 0.021             0.016            72                 0.021    
74-93-1..............  Methanethiol.........     (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
67-561...............  Methanol.............        78            310000               110                78            310000               110        
91-80-5..............  Methapyrilene........         0.16             51                 0.37              0.16             51                 0.37     
16752-77-5...........  Methomyl.............     (\1\)                 6                 4             (\1\)                 6                 3        
72-43-5..............  Methoxychlor.........         7               280          ................         7               280          ................
74-83-9..............  Methy bromide                 0.37            850                 4                 0.37            850                 4        
                        (Bromomethane).                                                                                                                 
74-87-3..............  Methyl chloride               0.096            91          ................         0.096            91          ................
                        (Chloromethane).                                                                                                                
78-93-3..............  Methyl ethyl ketone..        78            250000               110                78            250000               110        
1338-23-4............  Methyl ethyl ketone       (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
                        peroxide.                                                                                                                       
60-34-4..............  Methyl hydrazine.....     (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
108-10-1.............  Methyl isobutyl               8             38000                11                 8             38000                11        
                        ketone.                                                                                                                         

[[Page 66459]]
                                                                                                                                                        
80-62-6..............  Methyl methacrylate..        28            100000                33                28            100000                33        
66-27-3..............  Methyl                        0.12            590                24                 0.12            590                24        
                        methanesulfonate.                                                                                                               
91-57-6..............  Methyl naphthalene, 2-    (\1\)                 4             (\1\)             (\1\)                 4             (\1\)        
                        .                                                                                                                               
298-00-0.............  Methyl parathion.....         0.66              6               110                 0.66              6               110        
75-55-8..............  Methylaziridine, 2-..     (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
56-49-5..............  Methylcholanthrene, 3-    (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
                        .                                                                                                                               
74-95-3..............  Methylene bromide....         0.029         21000                 0.037             2             21000                 0.19     
75-09-2..............  Methylene chloride...         0.039           720                 0.09              0.039           720                 0.053    
101-14-4.............  Methylenebis, 4,4'-       (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
                        (2-chloroaniline).                                                                                                              
70-25-7..............  Methyl-nitro-             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
                        nitrosoguanidine                                                                                                                
                        (MNNG).                                                                                                                         
56-04-2..............  Methylthiouracil.....     (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
50-07-7..............  Mitomycin C..........     (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
7439-98-7............  Molybdenum...........         2              1200                 2                 2              1200                 2        
91-20-3..............  Naphthalene..........        14            430000                15                14            430000                15        
130-15-4.............  Naphthoquinone, 1,4-.        15              6900                37                15              6900                37        
86-88-4..............  Naphthyl-2-thiourea,      (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
                        1-.                                                                                                                             
134-32-7.............  Naphthylamine, 1-....         0.16             51                 0.37              0.16             51                 0.37     
91-59-8..............  Naphthylamine, 2-....         0.16             51                 0.37              0.16             51                 0.37     
7440-02-0............  Nickel...............         4              8600                 6                11              8600                14        
54-11-5..............  Nicotine and salts...         0.16             51                 0.37              0.16             51                 0.37     
88-74-4..............  Nitroaniline, 2-.....     (\1\)                88             (\1\)             (\1\)                88             (\1\)        
99-09-2..............  Nitroaniline, 3-.....     (\1\)                88             (\1\)             (\1\)                88             (\1\)        
100-01-6.............  Nitroaniline, 4-.....         0.028            88                 0.038             0.028            88                 0.038    
98-95-3..............  Nitrobenzene.........         0.084           520                 0.11              0.084           520                 0.11     
55-86-7..............  Nitrogen mustard.....     (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
51-75-2..............  Nitrogen mustard          (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
                        hydrochloride salt.                                                                                                             
126-85-2.............  Nitrogen mustard N-       (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
                        Oxide.                                                                                                                          
302-70-5.............  Nitrogen mustard N-       (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
                        Oxide, HCI salt.                                                                                                                
55-63-0..............  Nitroglycerine.......     (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
99-55-8..............  Nitro-o-toluidine, 5-         0.028            88                 0.038             0.028            88                 0.038    
88-75-5..............  Nitrophenol, 2-......         0.025            42                 0.034             0.025            42                 0.034    
100-02-7.............  Nitrophenol, 4-......     (\1\)                42             (\1\)             (\1\)                42             (\1\)        
79-46-9..............  Nitropropane, 2-.....     (\1\)                 3          ................     (\1\)                 3          ................
56-57-5..............  Nitroquinoline-1-             0.16             51                 0.37              0.16             51                 0.37     
                        oxide, 4-.                                                                                                                      
55-18-5..............  Nitrosodiethylamine..     (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
62-75-9..............  Nitrosodimethylamine.     (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
924-16-3.............  Nitrosodi-n-              (\1\)                 1             (\1\)             (\1\)                 1             (\1\)        
                        butylamine.                                                                                                                     
10595-95-6...........  Nitrosomethylethylami     (\1\)                 0.035         (\1\)             (\1\)                 0.035         (\1\)        
                        ne.                                                                                                                             
1116-54-7............  N-                        (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
                        Nitrosodiethanolamin                                                                                                            
                        e.                                                                                                                              
621-64-7.............  N-Nitrosodi-n-            (\1\)                 0.22          (\1\)             (\1\)                 0.22          (\1\)        
                        propylamine.                                                                                                                    
86-30-6..............  N-                            0.2            3600                 0.24              0.2            3600                 0.24     
                        Nitrosodiphenylamine.                                                                                                           
45490-40-0...........  N-Nitrosomethyl vinyl     (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
                        amine.                                                                                                                          
59-89-2..............  N-Nitrosomorpholine..         0.16             51                 0.37              0.16             51                 0.37     
759-73-9.............  N-Nitroso-N-ethylurea     (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
684-93-5.............  N-Nitroso-N-                  0.16             51                 0.37              0.16             51                 0.37     
                        methylurea.                                                                                                                     
100-75-4.............  N-Nitrosopiperidine..     (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
930-55-2.............  N-Nitrosopyrrolidine.     (\1\)                 0.36          (\1\)             (\1\)                 0.36          (\1\)        
13256-22-9...........  N-Nitrososarcosine...     (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
103-85-5.............  N-Phenylthiourea.....     (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
1615-80-1............  N,N-Diethylhydrazine.     (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
152-16-9.............  Octamethylpyrophospho         0.27             31                 0.37              0.27             31                 0.37     
                        ramide.                                                                                                                         
20816-12-0...........  Osmium tetroxide.....     (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
297-97-2.............  O,O-Diethyl O-                0.12            590                24                 0.12            590                24        
                        pyrazinyl                                                                                                                       
                        phosphorothioate.                                                                                                               
126-68-1.............  O,O,O-Triethyl                0.12            590                24                 0.12            590                24        
                        phosphorothioate.                                                                                                               
123-63-7.............  Paraldehyde..........         8             38000                22                 8             38000                22        
56-38-2..............  Parathion............         3                19            160000                 3                19            160000        
608-93-5.............  Pentachlorobenzene...         5              2300                 0.054             5              2300                 0.054    
76-01-7..............  Pentachloroethane....         0.024           140                 0.054             0.023           140                 0.053    
82-68-8..............  Pentachloro-                  0.27            140             (\1\)                 0.081           140             (\1\)        
                        nitrobenzene (PCNB).                                                                                                            
87-86-5..............  Pentachlorophenol....         0.002            22                 0.0022            0.002            22                 0.0022   
62-44-2..............  Phenacetin...........        15              6900                37                15              6900                37        
85-01-8..............  Phenanthrene.........     (\1\)                 4             (\1\)             (\1\)                 4             (\1\)        
108-95-2.............  Phenol...............        84            390000               110                84            390000               110        
62-38-4..............  Phenyl mercuric           (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
                        acetate.                                                                                                                        
25265-76-3...........  Phenylenediamines             0.16             51                 0.37              0.16             51                 0.37     
                        (N.O.S.).                                                                                                                       
108-45-2.............  Phenylenediamine, m-.         0.78           1700                 1                 0.78           1700                 1        

[[Page 66460]]
                                                                                                                                                        
106-50-3.............  Phenylenediamine, p-.         0.16             51                 0.37              0.16             51                 0.37     
298-06-2.............  Phorate..............         0.11            510          ................         0.11            510          ................
                       Phosphorodithioic         (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
                        acid,                                                                                                                           
                        dimethylethylester.                                                                                                             
298-06-6.............  Phosphorodithioic         (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
                        acid, o-o-diethyl                                                                                                               
                        ester.                                                                                                                          
3288-58-2............  Phosphorodithioic         (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
                        acid, o-o-diethyl-s-                                                                                                            
                        methyl.                                                                                                                         
2953-29-9............  Phosphorodithioic         (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
                        acid, trimethyl                                                                                                                 
                        ester.                                                                                                                          
85-44-9..............  Phthalic anhydride...     (\1\)              9600             (\1\)             (\1\)              9600             (\1\)        
109-06-8.............  Picoline, 2-.........         0.16             51                 0.37              0.16             51                 0.37     
1336-36-3............  Polychlorinated        See Table B              0.25              0.009      See Table B              0.25          (\1\)        
                        biphenyls.                                                                                                                      
12305-58-5...........  Pronamide............        21            230000                25                21            230000                25        
1120-71-4............  Propane sultone, 1,3-     (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
107-10-8.............  Propylamine, n-......         0.16             51                 0.37              0.16             51                 0.37     
51-52-5..............  Propylthiouracil.....         0.12            590                24                 0.12            590                24        
107-19-7.............  Propyn-1ol, 2-.......        39            130000                53                39            130000                53        
129-00-0.............  Pyrene...............        54             16000                 2                54             16000                 2        
110-86-1.............  Pyridine.............         0.16            930                 0.21              0.16            930                 0.21     
50-55-5..............  Reserpine............         0.16             51                 0.37              0.16             51                 0.37     
108-46-3.............  Resorcinol...........     (\1\)             (\1\)                 4             (\1\)             (\1\)             (\1\)        
81-07-2..............  Saccharin and salts..     (\1\)             (\1\)             (\1\)             (\1\)             (\1\)                          
94-59-7..............  Safrole..............         0.0035           28                 0.0044            0.0035           28                 0.0044   
7782-49-2............  Selenium.............         0.23            280                 0.12              0.93            280                 1        
7440-22-4............  Silver...............       200                 9          ................       200                 9          ................
18883-66-4...........  Streptozotocin.......     (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
57-24-9..............  Strychnine...........         0.045         (\1\)                 0.059             0.045         (\1\)                 0.059    
10-42-5..............  Stryene..............         0.91       ................         1                64          ................        70        
18496-25-8...........  Sulfide..............  ................  ................  ................  ................  ................  ................
1746-01-6............  TCDD, 2,3,7,8-.......     (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
95-94-3..............  Tetrachlorobenzene,           0.23           1600                 0.032             0.23           1600                 0.032    
                        1,2,4,5-.                                                                                                                       
630-20-6.............  Tetrachloroethane             0.024           370                 0.042             0.024           370                 0.042    
                        1,1,1,2-.                                                                                                                       
79-34-5..............  Tetrachloroethane,            0.0037           70                 0.0077            0.0037           70                 0.0077   
                        1,1,2,2-.                                                                                                                       
127-18-4.............  Tetrachloroethylene..         0.026        100000                 0.032             2            100000                 3        
58-90-2..............  Tetrachlorophenol,            2             35000                 2                 2             35000                 2        
                        2,3,4,6-.                                                                                                                       
107-49-3.............  Tetraethyl                (\1\)              6900             (\1\)             (\1\)              6900             (\1\)        
                        pyrophosphate.                                                                                                                  
107-49-3.............  Tetraethyl                (\1\)              6900             (\1\)             (\1\)              6900             (\1\)        
                        pyrophosphate.                                                                                                                  
3689-24-5............  Tetraethyldithiopyrop         0.23           1200          ................         0.23           1200          ................
                        hosphate.                                                                                                                       
7440-28-0............  Thallium (I).........         0.035            33                 0.048             0.05             33                 0.071    
62-55-5..............  Thioacetamide........     (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
39196-18-4...........  Thiofanox............         0.12            590                24                 0.12            590                24        
108-98-5.............  Thiophenol...........         0.12            590                24                 0.12            590                24        
79-19-6..............  Thiosemicarbazide....     (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
62-566...............  Thiourea.............     (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
137-26-8.............  Thiram...............     (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
7440-31-5............  Tin..................     (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
108-88-3.............  Toluene..............         6            560000                 7                30            560000                51        
584-84-9.............  Toluene diisocyanate.     (\1\)             (\1\)             (\1\)          ................  ................                  
95-80-7..............  Toluenediamine, 2,4--     (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
823-40-5.............  Toluenediamine, 2,6-.         0.16             51                 0.37              0.16             51                 0.37     
496-72-0.............  Toluenediamine, 3,4-.         0.16             51                 0.37              0.16             51                 0.37     
636-21-5.............  Toulidene,3,4-.......         0.16             51                 0.37              0.16             51                 0.37     
95-53-4..............  Toluidine, o-........     (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
106-49-0.............  Toluidine, p-........     (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
8001-35-2............  Toxaphene............     (\1\)             (\1\)               160             (\1\)             (\1\)                 3        
76-13-1..............  Trichloro-1,2,2-              0.77       ................         0.84           2200          ................     12000        
                        trifuoroethane,                                                                                                                 
                        1,1,2.                                                                                                                          
120-82-1.............  Trichlorobenzene,             0.69          62000                 3                 0.69          62000                 3        
                        1,2,4-.                                                                                                                         
71-55-6..............  Trichloroethane,             74            630000                 0.054            74            630000                 0.054    
                        1,1,1-.                                                                                                                         
79-00-5..............  Trichloroethane,              0.012           190                 0.039             0.007           190                 0.0077   
                        1,1,2-.                                                                                                                         

[[Page 66461]]
                                                                                                                                                        
79-01-6..............  Trichloroethylene....         0.024          3200                 0.031             0.038          3200                 0.049    
79-69-4..............  Trichlorofluoromethan        48            170000                61                48            170000                61        
                        e.                                                                                                                              
75-70-7..............  Trichloromethanethiol     (\1\)             (\1\)             (\1\)             (\1\)             (\1\)                22        
95-95-4..............  Trichlorophenol,             18             55000                22                18             55000                22        
                        2,4,5-.                                                                                                                         
88-06-2..............  Trichlorophenol,              0.054           160                 0.068             0.054           160                 0.068    
                        2,4,6-.                                                                                                                         
93-76-5..............  Trichlorophenoxyaceti         2               150                 2                 2               150                 2        
                        c acid, 2,4,5- (245-                                                                                                            
                        T).                                                                                                                             
93-72-1..............  Trichlorophenoxypropi         0.21            520                 0.28              1               520                 2        
                        onic acid, 2,4,5-                                                                                                               
                        (Silvex).                                                                                                                       
96-18-4..............  Trichloropropane,             1             14000                 1                 1             14000                 1        
                        1,2,3-.                                                                                                                         
99-35-4..............  Trintrobenzene, sym-.         0.0078           23                 0.011             0.0078           23                 0.011    
126-72-7.............  Tris (2,3-                (\1\)                 0.76          (\1\)             (\1\)                 0.76          (\1\)        
                        dibromopropyl)                                                                                                                  
                        phosphate.                                                                                                                      
52-24-4..............  Tris (1-azridinyl)        (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
                        phosphine sulfide.                                                                                                              
72-57-1..............  Trypan blue..........     (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
66-75-1..............  Uracil mustard.......     (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
7440-62-2............  Vanadium.............        10              2700                13                10              2700                13        
108-05-4.............  Vinyl acetate........        15              6900                37                15              6900                37        
75-01-4..............  Vinyl chloride.......         0.002             3                 0.011         (\1\)                 3                 0.00021  
81-81-2..............  Warfarin.............     (\1\)                 6                 4             (\1\)                 6                 3        
1330-20-7............  Xylenes (total)......        22            710000               100                22            710000               700        
7440-66-6............  Zinc.................        99             51000               130                99             51000               130        
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ See table B.                                                                                                                                        



                                                                                                                                                        

[[Page 66462]]
                                                  Table B.--Quantitation-Based Conditional Exit Levels                                                  
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                              MCL benchmark option                                Toxicity benchmark option             
                                             -----------------------------------------------------------------------------------------------------------
        CAS No.                 Name             Wastewater                Nonwastewater               Wastewater                Nonwastewater          
                                             -----------------------------------------------------------------------------------------------------------
                                               Totals  (mg/l)    Totals  (mg/kg)    Leach  (mg/l)    Totals  (mg/l)    Totals  (mg/kg)    Leach  (mg/l) 
--------------------------------------------------------------------------------------------------------------------------------------------------------
208-96-8..............  Acenaphthylene......         0.02       ................         0.02              0.02       ................  ................
75-36-5...............  Acetyl chloride.....     (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
591-08-2..............  Acetyl-2-thiourea,..         1          ................  ................         1          ................  ................
107-02-8..............  Acrolein............         0.013      ................  ................         0.013      ................  ................
79-06-1...............  Acrylamide..........         0.01              0.1               0.01              0.01              0.1               0.01     
107-13-1..............  Acrylonitrile.......         0.008      ................         0.008      ................         0.008                      
1402-68-2.............  Aflatoxins..........     (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
116-06-3..............  Aldicarb............         0.05       ................  ................         0.05       ................  ................
309-00-2..............  Aldrin..............         0.000034   ................         0.000034          0.000034   ................         0.000034 
107-18-6..............  Allyl alcohol.......     (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
2763-96-4.............  Aminomethyl-3-           (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
                         isoxazolol, 5-.                                                                                                                
504-24-5..............  Aminopyridine, 4-...     (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
61-82-5...............  Amitrole............     (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
120-12-7..............  Anthracene..........         0.007      ................         0.007             0.007      ................         0.007    
7440-38-2.............  Arsenic.............  ................  ................  ................         0.0005     ................  ................
2465-27-2.............  Auramine............     (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
115-02-6..............  Azaserine...........     (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
92-87-5...............  Benzidine...........         0.0025            0.042             0.0025            0.0025            0.042             0.0025   
98-07-7...............  Benzotrichloride....     (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
50-32-8...............  Benzo(a)pyrene......  ................  ................  ................  ................  ................         0.000023 
205-82-3..............  Benzo(j)fluoranthene  ................  ................  ................  ................  ................         0.0002   
207-08-9..............  Benzo(k)fluoranthene  ................  ................  ................  ................  ................         0.0002   
191-24-2..............  Benzo[g,h,i]perylene  ................  ................  ................  ................  ................         0.0008   
56-55-3...............  Benz(a)anthracene...  ................  ................         0.000013   ................  ................         0.000013 
225-51-4..............  Benz[c]acridine.....  ................  ................  ................  ................  ................         0.0005   
542-88-1..............  Bis(chloromethyl)        (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
                         ether.                                                                                                                         
357-57-3..............  Brucine.............        20             (\1\)                20                20             (\1\)                20        
86-74-8...............  Carbazole...........     (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
353-50-4..............  Carbon oxyfluoride..     (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
75-87-6...............  Chloral.............     (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
305-03-3..............  Chlorambucil........     (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
57-74-9...............  Chlordane...........         0.00004    ................  ................         0.00004    ................  ................
494-03-1..............  Chlornaphazin.......     (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
107-20-0..............  Chloroacetaldehyde..     (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
110-75-8..............  Chloroethyl vinyle       (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
                         ether, 2-.                                                                                                                     
107-30-2..............  Chloromethyl methyl      (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
                         ether.                                                                                                                         
5344-82-1.............  Chlorophenyl             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
                         thiourea, 1-o-.                                                                                                                
542-76-7..............  Chloropropionitrile,  ................  ................         0.1               0.1        ................         0.1      
                         3-.                                                                                                                            
6358-53-8.............  Citrus red No. 2....     (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
7440-48-4.............  Cobalt..............  ................  ................         0.5        ................  ................  ................
57-12-5...............  Cyanida.............         0.2        ................  ................         0.2        ................  ................
14901-08-7............  Cycasin.............     (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
108-94-1..............  Cyclohexanone.......        10          ................  ................        10             (\1\)             (\1\)        
131-89-5..............  Cyclohexyl-4,6-              0.1           (\1\)                 0.1               0.1           (\1\)                 0.1      
                         dinitrophenol, 2-.                                                                                                             
50-18-0...............  Cyclophosphamide....     (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
20830-81-3............  Daunomycin..........     (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
53-19-0...............  DDD (o,p')..........     (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
72-55-9...............  DDE.................         0.000058   ................  ................         0.000058   ................  ................
3424-82-6.............  DDE (o,p')..........     (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
50-29-3...............  DDT.................         0.000081   ................  ................         0.000081   ................  ................
789-02-6..............  DDT (o,p')..........     (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
192-65-4..............  Dibenzo-              ................  ................  ................  ................  ................         0.001    
                         [a,e]ypyrene.                                                                                                                  
189-64-0..............  Dibenzo- [a,h]pyrene  ................  ................  ................  ................  ................         0.0002   
189-64-9..............  Dibenzo- [a,i]pyrene  ................  ................  ................  ................  ................         0.0002   
194-59-2..............  Dibenzo-                    (0.01       ................         0.01              0.01       ................         0.01     
                         [c,g]carbazole, 7H-.                                                                                                           
226-36-8..............  Dibenz-               ................  ................  ................  ................  ................         0.0002   
                         (a,h)acridine.                                                                                                                 
53-70-3...............  Dibenz- (a,h)ant-            0.00003           0.084             0.00003           0.00003           0.084             0.00003  
                         hracene.                                                                                                                       
224-42-0..............  Dibenz[a,j] acridine  ................  ................  ................  ................  ................         0.001    
311-45-5..............  Diethyl-p-               (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
                         nitrophenyl                                                                                                                    
                         phosphate.                                                                                                                     
56-53-1...............  Diethylstibestrol...         0.0078            1                 0.0078            0.0078            1                 0.0078   
77-78-1...............  Dimethyl sulfate....     (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
119-93-7..............  Dimethybenzidine,            0.0033            0.7               0.0033            0.0033            0.7               0.0033   
                         3,3'-.                                                                                                                         
57-97-6...............  Dimethyl- benz(a)-           0.00037           0.039             0.00037           0.00037           0.039             0.00037  
                         anthracene, 7,12-.                                                                                                             

[[Page 66463]]
                                                                                                                                                        
79-44-7...............  Dimethylcarbamoyl        (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
                         chloride.                                                                                                                      
119-90-4..............  Dimethy- oxyben-      ................         7          ................  ................         7          ................
                         zidine, 3,3'-.                                                                                                                 
100-25-4..............  Dinitrobenzene, 1,4-         0.04       ................         0.04              0.04       ................         0.04     
534-52-1..............  Dinitro-o-cresol,            0.05       ................         0.05              0.05       ................         0.05     
                         4,6-.                                                                                                                          
541-53-7..............  Dithiobiuret........     (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
145-73-3..............  Endothall...........         0.1           (\1\)          ................         0.1           (\1\)          ................
51-43-4...............  Epinephrine.........     (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
62-50-0...............  Ethyl                 ................         0.018      ................  ................         0.018      ................
                         methanesulfonate.                                                                                                              
96-45-7...............  Ethylene thiourea...     (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
151-56-4..............  Ethyleneimine            (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
                         (aziridine).                                                                                                                   
52-85-7...............  Famphur.............         0.02       ................  ................         0.02       ................  ................
640-19-7..............  Fluoracetamide, 2-..     (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
62-74-8...............  Fluoracetic acid,        (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
                         sodium salt.                                                                                                                   
16984-48-8............  Fluoride............  ................  ................  ................  ................  ................  ................
50-00-0...............  Formaldehyde........         0.023      ................  ................         0.023      ................  ................
765-34-4..............  Glycidylaldehyde....     (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
76-44-8...............  Heptachlor..........         0.00004    ................  ................         0.00004    ................  ................
118-74-1..............  Hexachlorobenzene...         0.0016     ................  ................         0.0016     ................         0.0016   
70-30-4...............  Hexachlorophene.....         0.21              2                 0.21              0.21              2                 0.21     
757-58-4..............  Hexaethyl                (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
                         tetraphosphate.                                                                                                                
302-01-2..............  Hydrazine...........     (\1\)          ................     (\1\)             (\1\)          ................     (\1\)        
193-39-5..............  indeno(1,2,3-         ................  ................         0.000043   ................  ................         0.000043 
                         cde)pyrene.                                                                                                                    
465-73-6..............  Isodrin.............         0.02       ................  ................         0.02       ................  ................
143-50-0..............  Kepone..............         0.016             0.097             0.016             0.016             0.097             0.016    
303-43-4..............  Lasiocarpine........     (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
108-31-6..............  Maleic anhydride....     (\1\)          ................     (\1\)             (\1\)          ................     (\1\)        
148-82-3..............  Melphalan...........     (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
74-93-1...............  Methanethiol........     (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
16752-77-5............  Methomyl............         0.05       ................  ................         0.05       ................  ................
1338-23-4.............  Methyl ethyl ketone      (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
                         peroxide.                                                                                                                      
60-34-4...............  Methyl hydrazine....     (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
91-57-6...............  Methyl naphthalene,          0.01       ................         0.01              0.01       ................         0.01     
                         2-.                                                                                                                            
75-55-8...............  Methylaziridine, 2-.     (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
56-49-5...............  Methylcholanthrene,          0.01              0.046             0.01              0.01              0.046             0.01     
                         3-.                                                                                                                            
101-14-4..............  Methylenebis, 4,4'-      (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
                         (2-chloroaniline).                                                                                                             
70-25-7...............  Methyl-nitro-            (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
                         nitrosoguanidine                                                                                                               
                         (MNNG).                                                                                                                        
56-04-2...............  Methylthiouracil....     (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
50-07-7...............  Mitomycin C.........     (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
86-88-4...............  Naphthyl-2-thiourea,     (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
                         1-.                                                                                                                            
88-74-4...............  Nitroaniline, 2-....         0.05       ................         0.05              0.05       ................         0.05     
99-09-2...............  Nitroaniline, 3-....         0.05       ................         0.05              0.05       ................         0.05     
55-86-7...............  Nitrogen mustard....     (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
51-75-2...............  Nitrogen mustard         (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
                         hydrochloride salt.                                                                                                            
126-85-2..............  Nitrogen mustard N-      (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
                         Oxide.                                                                                                                         
302-70-5..............  Nitrogen mustard N-      (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
                         Oxide, HCI salt.                                                                                                               
55-63-0...............  Nitroglycerine......     (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
110-02-7..............  Nitrophenol, 4-.....         0.05       ................         0.05              0.05       ................         0.05     
79-46-9...............  Nitropropane, 2-....         0.0058     ................  ................         0.0058     ................  ................
55-18-5...............  Nitrosodiethylamine.         0.002         (\1\)                 0.002             0.002             1                 0.002    
62-75-9...............  Nitrosodimethylamine         0.0006            0.074             0.0006            0.0006            0.074             0.0006   
924-16-3..............  Nitrosodi-n-                 0.06       ................         0.06              0.06       ................         0.06     
                         butylamine.                                                                                                                    
10595-95-6............  Nitrosomethylethylam         0.028      ................         0.028             0.028      ................         0.028    
                         ine.                                                                                                                           
1116-54-7.............  N-                           0.01              0.7               0.01              0.01              0.7               0.01     
                         Nitrosodiethanolami                                                                                                            
                         ne.                                                                                                                            
621-64-7..............  N-Nitrosodi-n-               0.026      ................         0.026             0.026      ................         0.026    
                         propyamine.                                                                                                                    

[[Page 66464]]
                                                                                                                                                        
4549-40-0.............  N-Nitrosomethy vinyl     (\1\)             (\1\)             (\1\)             (\1\)          (\1\) D(\1\)                      
                         amine.                                                                                                                         
759-73-9..............  N-Nitroso-N-             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
                         ethylurea.                                                                                                                     
615-53-2..............  N-Nitroso-N-             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
                         methylurethane.                                                                                                                
16543-55-8............  N-Nitrosonornicotine     (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
100-75-4..............  N-Nitrosopiperidine.         0.0014            0.033             0.0014            0.0014            0.033             0.0014   
930-55-2..............  N-Nitrosopyrrolidine         0.0047     ................         0.0047            0.0047     ................         0.0047   
13256-22-9............  N-Nitrososarcosine..     (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
103-85-5..............  N-Phenylthiourea....     (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
1615-80-1.............  N,N-Diethylhydrazine     (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
20816-12-0............  Osmium tetroxide....         3               200                 3                 3               200                 3        
82-68-8...............  Pentachloronitrobenz  ................  ................         0.02       ................  ................         0.02     
                         ene (PCNB).                                                                                                                    
85-01-8...............  Phenanthrene........         0.006      ................         0.006             0. 006     ................         0.006    
62-38-4...............  Phenyl mercuric          (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
                         acetate.                                                                                                                       
                        Phosphorodithioic        (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
                         acid,                                                                                                                          
                         dimethylethylester.                                                                                                            
298-06-6..............  Phosphorodithioic        (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
                         acid, o-o-diethyl                                                                                                              
                         ester.                                                                                                                         
3288-58-2.............  Phosphorodithioic        (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
                         acid, o-o-diethyl-s-                                                                                                           
                         methlyl.                                                                                                                       
2953-29-9.............  Pyhosphorodithioic       (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
                         acid, trimethyl                                                                                                                
                         ester.                                                                                                                         
85-44-9...............  Phthalic anhydride..     (\1\)          ................     (\1\)             (\1\)          ................     (\1\)        
1336-36-3.............  Polychlorinated              0.0005     ................  ................         0.0005     ................         0.0005   
                         biphenyls.                                                                                                                     
1120-71-4.............  Propane sultone, 1,3-    (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
                         .                                                                                                                              
108-46-3..............  Resorcinol..........         0.1               7          ................         0.1               7          ................
81-07-2...............  Saccharin and salts.     (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
18883-66-4............  Streptozotocin......     (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
57-24-9...............  Strychnine..........  ................         3          ................  ................         3          ................
1746-01-6.............  TCDD, 2, 3, 7.8-....         1.000E-08  ................  ................         1.000E-08  ................         1.000E-08
107-49-3..............  Tetraethyl               (\1\)          ................     (\1\)             (\1\)          ................     (\1\)        
                         pyrophosphate.                                                                                                                 
62-55-5...............  Thioacetamide.......         1             (\1\)                 1                 1             (\1\)                 1        
79-19-6...............  Thiosemicarbazide...     (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
62-56-6...............  Thiourea............     (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
137-26-8..............  Thiram..............         0.05       ................  ................         0.05       ................  ................
7440-31-5.............  Tin.................         8               500                 8                 8               500                 8        
584-84-9..............  Toluene diisocyanate     (\1\)          ................     (\1\)             (\1\)          ................     (\1\)        
95-80-7...............  Toluenediamine, 2,4-         0.013             1                 0.013             0.013             1                 0.013    
95-53-4...............  Toluidine, 0-.......         0.012      ................         0.012             0.012      ................         0.012    
106-49-0..............  Toluidine, p-.......         0.017      ................         0.017             0.017      ................         0.017    
8001-35-2.............  Toxaphene...........         0.0013            0.03       ................         0.0013            0.03       ................
75-70-7...............  Trichloromethanethio     (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
                         l.                                                                                                                             
126-72-7..............  Tris (2, 3-                  0.025      ................         0.025             0.025      ................         0.025    
                         dibromopropyl)                                                                                                                 
                         phosphate.                                                                                                                     
52-24-4...............  Tris (1-azridinyl)       (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
                         phosphine sulfide.                                                                                                             
72-57-1...............  Trypan blue.........     (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
66-75-1...............  Uracil mustard......     (\1\)             (\1\)             (\1\)             (\1\)             (\1\)             (\1\)        
75-01-4...............  Vinyl chloride......  ................  ................  ................         0.00017    ................  ................
81-81-2...............  Warfarin............         0.05       ................  ................         0.05       ................  ................
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ No testing required; additional LDR requirements apply.                                                                                             



PART 266--STANDARDS FOR THE MANAGEMENT OF SPECIFIC HAZARDOUS WASTES 
AND SPECIFIC TYPES OF HAZARDOUS WASTE FACILITIES

    9. The authority citation for part 266 continues to read as 
follows:
    Authority: 42 U.S.C. 6905, 6912(a), 6924, and 6934.

    10. Section 266.20 is amended by revising the first sentence of 
paragraph (b) to read as follows:


* * * * *

    (b) Products produced for the general public's use that are used in 
a manner that constitutes disposal and that contain recyclable 
materials are not presently subject to regulation if, for each 
hazardous constituent in each recyclable material (i.e., hazardous 
waste) that they contain, they meet the 

[[Page 66465]]
applicable exit levels in appendix X to Part 261 of this chapter. * * *

PART 268--LAND DISPOSAL RESTRICTIONS

    11. The authority citation for part 268 continues to read as 
follows:

    Authority: 42 U.S.C. 6905, 6912(a) 6921, and 6924.
    12. Section 268.2 is amended by adding paragraph (j) to read as 
follows:
* * * * *
    (j) Land treatment means waste is applied onto or incorporated into 
the soil surface.
    13. Section 268.40 is amended by revising the first sentence of 
paragraph (a), revising paragraph (e), and adding paragraph (g) to read 
as follows:


Sec. 268.41  Applicability of treatment standards

    (a) Except as provided in paragraph (g) of this section, a waste 
identified in the table ``Treatment Standards for Hazardous Wastes'' 
may be land disposed only if it meets the requirements found in the 
table. * * *
* * * * *
    (e) Except as provided in paragraph (g) of this section, for all 
characteristic wastes (D001, D002, and D012-D043) that are subject to 
treatment standards in the following table ``Treatment Standards for 
Hazardous Wastes,'' all underlying constituents (as defined in 
Sec. 268.20(i)) must meet Universal Treatment Standards, found in 
Sec. 268.48, Table UTS, prior to land disposal.
* * * * *
    (g) Wastes subject to either the treatment standards described in 
paragraph (a)(1) or (a)(2) of this section or the Universal Treatment 
Standards described in paragraph (e) of this section may be land 
disposed if they meet either of the alternative, risk-based standards 
found in subpart F and G of this part and representing levels at which 
threats to human health or the environment are minimized.
    14. Part 268 is amended by adding Subpart F consisting of 
Sec. 268.60 to read as follows:

Subpart F--Minimize Threat Levels Without Management Requirements


Sec. 268.60  Minimize threat levels.

    (a) Table ``Minimize Threat Levels'' identifies risk-based 
standards representing levels at which threats to human health and the 
environment are minimized. These levels may be used as alternatives to 
waste-specific treatment standards in the table to Sec. 268.40 and to 
the Universal Treatment Standards in the table to Sec. 268.48. 
Nonwastewaters must meet both the total and waste extract levels 
contained in the table of ``Minimize Threat Levels''.
    (b) Wastes identified in the Table to Sec. 268.40 may be land 
disposed if they meet either the requirements in that Table or the 
standards in the Minimize Threat Table for all constituents. 
Characteristic wastes that are subject to the requirement for meeting 
Universal Treatment Standards under Sec. 268.40(e) must also meet the 
requirements of Table UTS or the Minimize Threat Table for all 
underlying hazardous constituents as defined in Sec. 268.2(i).
    (c) Wastes containing either regulated hazardous constituents under 
the Table to Sec. 268.40 or UTS constituents which do not have 
treatment standards listed in the Minimize Threat Table must continue 
to comply with treatment standards for these constituents in the tables 
to Sec. 268.40 or Sec. 268.48 prior to land disposal.

                                    268.60  Table 1.--Minimize Threat Levels                                    
----------------------------------------------------------------------------------------------------------------
                                                            WW standard  (mg/   NWW standard      NWW standard  
             CAS                     Constituent name              l)              (mg/kg)           (mg/l)     
----------------------------------------------------------------------------------------------------------------
83-32-9......................  Acenaphthene...............        31              9500                 5        
67-64-1......................  Acetone....................        16             17000                 6        
75-05-8......................  Acetonitrile...............  ................       920                 0.3      
98-86-2......................  Acetophenone...............        17              1200                 6        
107-05-1.....................  Allyl chloride.............  ................       260          ................
7440-39-3....................  Barium.....................        33              2100                16        
71-43-2......................  Benzene....................  ................       110                 0.0054   
117-81-7.....................  Bis(2-ethylhexyl)phthalate.  ................       230                 0.0011   
75-27-4......................  Bromodichloromethane.......  ................        19                 0.0025   
75-25-2......................  Bromoform (Tribromomethane)  ................       170                 0.018    
71-36-3......................  Butanol....................        16             18000                 6        
88-85-7......................  Butyl-4,6-dinitrophenol, 2-         0.19            770                 0.064    
                                sec- (Dinoseb).                                                                 
85-68-7......................  Butylbenzylphthalate.......       240                87                64        
75-15-0......................  Carbon disulfide...........  ................       330                 6        
56-23-5......................  Carbon tetrachloride.......  ................         9                 0.0016   
126-99-8.....................  Chloro-1,3-butadiene, 2-            0.52            290          ................
                                (Chloroprene).                                                                  
106-47-8.....................  Chloroaniline, p-..........  ................       140                 0.16     
108-90-7.....................  Chlorobenzene..............         2              2500                 1        
124-48-1.....................  Chlorodibromomethane.......  ................        28                 0.0018   
67-66-3......................  Chloroform.................  ................         7                 0.017    
95-57-8......................  Chlorophenol, 2-...........         0.9             100                 0.32     
218-01-9.....................  Chrysene...................         0.1              35                 0.0012   
108-39-4.....................  Cresol, m-.................         8             22000                 3        
95-48-7......................  Cresol, o-.................         8             27000                 3        
106-44-5.....................  Cresol, p-.................         0.84           2600                 0.32     
84-74-2......................  Di-n-butyl phthalate.......       230             90000                25        
117-84-0.....................  Di-n-octyl phthalate.......  ................      4500                 0.1      
95-50-1......................  Dichlorobenzene, 1,2-......        15             50000                 6        
106-46-7.....................  Dichlorobenzene, 1,4-......  ................        64                 0.011    
75-71-8......................  Dichlorodifluoromethane....        15              8100                12        
75-34-3......................  Dichloroethane, 1,1-.......  ................        24                 0.00006  
156-60-5.....................  Dichloroethylene, trans-1,2-        3             14000                 1        
                                .                                                                               
120-83-2.....................  Dichlorophenol, 2,4-.......         0.62            770                 0.18     
94-75-7......................  Dichlorophenoxyacetic acid,         2              3100                 0.6      
                                2,4- (2,4-D).                                                                   
84-66-2......................  Diethyl phthalate..........       190              4500                54        
131-11-3.....................  Dimethyl phthalate.........        78          ................  ................

[[Page 66466]]
                                                                                                                
105-67-9.....................  Dimethylphenol, 2,4-.......         4             11000                 1        
51-28-5......................  Dinitrophenol, 2,4-........         0.27       ................  ................
121-14-2.....................  Dinitrotoluene, 2,4-.......  ................       210                 0.11     
606-20-2.....................  Dinitrotoluene, 2,6-.......  ................        86                 0.064    
122-39-4.....................  Diphenylamine..............        15             12000                 3        
298-04-4.....................  Disulfoton.................  ................        43                13        
72-20-8......................  Endrin.....................         0.073             0.26             32        
141-78-6.....................  Ethyl acetate..............       390            270000               110        
60-29-7......................  Ethyl ether................        27             41000                11        
97-63-2......................  Ethyl methacrylate.........        24              3400                 7        
100-41-4.....................  Ethylbenzene...............        39            550000                 8        
206-44-0.....................  Fluoranthene...............        28              6000                 2        
86-73-7......................  Fluorene...................        22             90000                 3        
76-44-8......................  Heptachlor.................  ................         8          ................
87-68-3......................  Hexachloro-1,3-butadiene...  ................        36                 0.0069   
319-85-7.....................  Hexachlorocyclohexane, beta-        0.00044           0.12              0.00021  
                                 (beta-BHC).                                                                    
58-89-9......................  Hexachlorocyclohexane,       ................         0.1               0.69     
                                gamma- (Lindane).                                                               
77-47-4......................  Hexachlorocyclopentadiene..  ................      1500          ................
67-72-1......................  Hexachloroethane...........  ................        81                 0.033    
78-83-1......................  Isobutyl alcohol...........        39             55000                15        
7439-92-1....................  Lead.......................        30               570                12        
7439-97-6....................  Mercury....................         0.3               0.6               0.14     
67-56-1......................  Methanol...................        78            140000                30        
72-43-5......................  Methoxychlor...............         7                19          ................
74-83-9......................  Methyl bromide                      0.37            500                 0.92     
                                (Bromomethane).                                                                 
74-87-3......................  Methyl chloride              ................        91          ................
                                (Chloromethane).                                                                
78-93-3......................  Methyl ethyl ketone........        78            110000                30        
108-10-1.....................  Methyl isobutyl ketone.....         8             17000                 3        
80-62-6......................  Methyl methacrylate........        28             40000                 8        
298-00-0.....................  Methyl parathion...........         0.66       ................  ................
74-95-3......................  Methylene bromide..........         2              8400                 0.19     
75-09-2......................  Methylene chloride.........  ................       310                 0.015    
91-20-3......................  Naphthalene................        14            120000                 3        
7440-02-0....................  Nickel.....................        11               110                 5        
98-95-3......................  Nitrobenzene...............         0.084            45                 0.032    
56-38-2......................  Parathion..................         3          ................  ................
608-93-5.....................  Pentachlorobenzene.........         5          ................  ................
82-68-8......................  Pentachloronitrobenzene             0.081      ................  ................
                                (PCNB).                                                                         
108-95-2.....................  Phenol.....................        84            160000                32        
298-02-2.....................  Phorate....................         0.11            160          ................
23950-58-5...................  Pronamide..................        21               440                 6        
129-00-0.....................  Pyrene.....................        54             16000                 2        
110-86-1.....................  Pyridine...................         0.16            810                 0.06     
7782-49-2....................  Selenium...................         0.93       ................  ................
7440-22-4....................  Silver.....................       200          ................  ................
95-94-3......................  Tetrachlorobenzene, 1,2,4,5-     0;23               170                 0.032    
                                .                                                                               
630-20-6.....................  Tetrachloroethane, 1,1,1,2-  ................       130                 0.0078   
79-34-5......................  Tetrachloroethane, 1,1,2,2-  ................        29                 0.0077   
127-18-4.....................  Tetrachloroethylene........         2             13000                 0.68     
58-90-2......................  Tetrachlorophenol, 2,3,4,6-         2              6200                 0.58     
7440-28-0....................  Thallium (l)...............  ................         5                 0.019    
108-88-3.....................  Toluene....................        30            180000                13        
76-13-1......................  Trichloro-1,2,2,-                2200          ................  ................
                                trifluoroethane, 1,1,2-.                                                        
120-82-1.....................  Trichlorobenzene, 1,2,4-...         0.69           3500                 1        
71-55-6......................  Trichloroethane, 1,1,1-....        74             48000                 0.054    
79-00-5......................  Trichloroethane, 1,1,2-....  ................        11                 0.0018   
79-01-6......................  Trichloroethylene..........  ................       570                 0.013    
75-69-4......................  Trichlorofluoromethane.....        48             26000                16        
95-95-4......................  Trichlorophenol, 2,4,5-....        18             12000                 4        
88-06-2......................  Trichlorophenol, 2,4,6-....         0.054           120                 0.015    
93-76-5......................  Trichlorophenoxyacetic              2                63                 0.64     
                                acid, 2,4,5- (245-T).                                                           
93-72-1......................  Trichlorophenoxypropionic           1          ................  ................
                                acid, 2,4,5- (Silvex).                                                          
96-18-4......................  Trichloropropane, 1,2,3-...         1               870                 0.34     
7440-62-2....................  Vanadium...................        10               250                 4        
1330-20-7....................  Xylenes (total)............        22            170000               150        
7440-66-6....................  Zinc.......................        99               320                38        
----------------------------------------------------------------------------------------------------------------


                                                                                                
[[Page 66467]]

    15. Part 268 is amended by adding subpart G consisting of 
Secs. 268.70 and 268.71 to read as follows:

Subpart G--Conditioned Minimize Threat Levels with Management 
Requirements


Sec. 268.70  Conditioned Minimize Threat Levels.

    (a) Table ``Conditioned Minimize Threat Levels'' identifies risk-
based standards representing levels at which threats to human health 
and the environment are minimized for wastes which are placed in 
landfills or monofills (but not land application units). These levels 
may be used as alternatives to waste-specific treatment standards in 
the table to Sec. 268.40 and to the Universal Treatment Standards in 
the table to Sec. 268.48 for wastes which comply with the requirements 
of Sec. 268.71. Nonwastewaters must meet both the total and waste 
extract levels contained in the table of ``Minimize Threat Levels''.
    (b) Wastes identified in the Table to Sec. 268.40 may be land 
disposed if they meet, for all hazardous constituents identified in the 
table to Sec. 268.40, either the requirements in that table, the 
standards in the Minimize Threat Table in subpart F, or, if they meet 
the requirements in Sec. 268.71, the standards in the Conditioned 
Minimize Threat Table. Characteristic wastes that are subject to the 
requirement for meeting Universal Treatment Standards under 
Sec. 268.40(e) must also meet the requirements of Table UTS, the 
Minimize Threat Table, or, if they meet the requirements of 
Sec. 268.71, the Conditioned Minimize Threat Table, for all underlying 
hazardous constituents as defined in Sec. 268.2(i).
    (c) Wastes containing either regulated hazardous constituents under 
the Table to Sec. 268.40 or UTS constituents which do not have 
treatment standards listed in the Minimize Threat Table must continue 
to comply with treatment standards for these constituents in the tables 
to Sec. 268.40, Sec. 268.48, or the Minimize Threat Table to Subpart F 
prior to land disposal.

                              268.70  Table 1.--Conditional Minimize Threat Levels                              
----------------------------------------------------------------------------------------------------------------
                                                            WW standard  (mg/   NWW standard      NWW standard  
             CAS                     Constituent name              l)              (mg/kg)           (mg/l)     
----------------------------------------------------------------------------------------------------------------
83-32-9......................  Acenaphthene...............        31             63000                13        
67-64-1......................  Acetone....................        16             39000                21        
75-05-8......................  Acetonitrile...............  ................      2200                 1        
98-86-2......................  Acetophenone...............        17             75000                22        
107-05-1.....................  Allyl chloride.............  ................       260          ................
62-53-3......................  Aniline....................  ................       170                 0.072    
7440-39-3....................  Barium.....................        33             34000                45        
71-43-2......................  Benzene....................  ................       250                 0.023    
39638-32-9...................  Bis (2-chloroisopropyl)      ................        97                 0.0088   
                                ether.                                                                          
117-81-7.....................  Bis(2-ethylhexyl)phthalate.  ................       740                 0.0011   
75-27-4......................  Bromodichloromethane.......  ................       240                 0.011    
75-25-2......................  Bromoform (Tribromomethane)  ................      1600                 0.081    
71-36-3......................  Butanol....................        16             41000                21        
88-85-7......................  Buthl-4,6-dinitrophenol, 2-         0.19           6000                 0.24     
                                sec- (Dinoseb).                                                                 
85-68-7......................  Butylbenzylphthalate.......       240                87                67        
7440-43-9....................  Cadmium....................  ................       110                 0.32     
75-15-0......................  Carbon disulfide...........  ................      3800                24        
56-23-5......................  Carbon tetrachloride.......  ................       130                 0.0077   
126-99-8.....................  Chloro-1,3-butadiene, 2-            0.52           1700          ................
                                (Chloroprene).                                                                  
106-47-8.....................  Chloroaniline, p-..........  ................      5800                 0.56     
108-90-7.....................  Chlorobenzene..............         2             41000                 6        
124-48-1.....................  Chlorodi- bromo- methane...  ................       200                 0.0079   
67-66-3......................  Chloroform.................  ................        76                 0.075    
95-57-8......................  Chlorophenol, 2-...........         0.9            8500                 1        
7440-47-3....................  Chromium...................  ................        16                 2        
218-01-9.....................  Chrysene...................         0.1              35                 0.0012   
108-39-4.....................  Cresol, m-.................         8             30000                11        
95-48-7......................  Cresol, o-.................         8             46000                11        
106-44-5.....................  Cresol, p-.................         0.84           2900                 1        
72-54-8......................  DDD........................  ................         0.26           6800        
50-29-3......................  DDT........................  ................         0.11              0.0054   
84-74-2......................  Di-n-butyl phthalate.......       230             90000                25        
117-84-0.....................  Di-n-octyl phthalate.......  ................     21000                 0.1      
95-50-1......................  Dichlorobenzene, 1,2-......        15            530000                32        
106-46-7.....................  Dichlorobenzene, 1,4-......  ................       650                 0.06     
75-71-8......................  Dichloro- difluoro- methane        15              8400                45        
75-34-3......................  Dichloroethane, 1,1-.......  ................       110                 0.00021  
107-06-2.....................  Dichloroethane, 1,2-.......  ................        59                 0.00021  
156-60-5.....................  Dichloro- ethylene, trans-          3            130000                 4        
                                1,2-.                                                                           
120-83-2.....................  Dichlorophenol, 2,4-.......         0.62            770                 0.76     
94-75-7......................  Dichlorophen- oxyacetic             2             12000                 2        
                                acid, 2,4- (2,4-D).                                                             
78-87-5......................  Dichloropropane, 1,2-......  ................       180                 0.011    
10061-01-5...................  Dichloropropene, cis-1,3-..  ................        65             10000        
10061-02-6...................  Dichloropro- pene, trans-    ................        62             10000        
                                1,3-.                                                                           
84-66-2......................  Diethyl phthalate..........       190             19000               220        
131-11-3.....................  Dimethyl phthalate.........        78          ................  ................
105-67-9.....................  Dimethylphenol, 2,4-.......         4             24000                 5        
51-28-5......................  Dinitrophenol, 2,4-........         0.27            450                 0.37     
121-14-2.....................  Dinitrotoluene, 2,4-.......  ................      1400                 0.39     

[[Page 66468]]
                                                                                                                
606-20-2.....................  Dinitrotoluene, 2,6-.......  ................       420                 0.22     
122-39-4.....................  Diphenyla- mine............        15             12000                15        
298-04-4.....................  Disulfoton.................  ................        58               120        
72-20-8......................  Endrin.....................         0.073            27               770        
141-78-6.....................  Ethyl acetate..............       390            600000               510        
60-29-7......................  Ethyl ether................        27            260000                37        
97-63-2......................  Ethyl methacrylate.........        24            100000                27        
100-41-4.....................  Ethylbenzene...............        39          ................        42        
206-44-0.....................  Fluoranthene...............        28             21000                 2        
86-73-7......................  Fluorene...................        22             90000                 7        
76-44-8......................  Heptachlor.................  ................         8          ................
1024-57-3....................  Heptachlor epoxide.........  ................         0.56             10        
87-68-3......................  Hexachloro-1,3-butadiene...  ................       290                 0.0069   
319-84-6.....................  Hexachloro- cyclohex- ane,   ................         0.18              2        
                                alpha- (alpha-BHC).                                                             
319-85-7.....................  Hexachloro- cyclohex- ane,          0.00044           0.64              0.0009   
                                beta- (beta-BHC).                                                               
58-89-9......................  Hexachloro- cyclohex- ane,   ................         0.75              9        
                                gamma- (Lindane).                                                               
77-47-4......................  Hexachloro- cyclopent-       ................      1500          ................
                                adiene.                                                                         
67-72-1......................  Hexachloroethane...........  ................       890                 0.11     
78-83-1......................  Isobutyl alcohol...........        39            120000                53        
7439-92-1....................  Lead.......................        30              1600                41        
7439-97-6....................  Mercury....................         0.3              39                 0.4      
67-56-1......................  Methanol...................        78            310000               110        
72-43-5......................  Methoxychlor...............         7               280          ................
74-83-9......................  Methyl bromide (Bromo-              0.37            850                 4        
                                methane).                                                                       
74-87-3......................  Methyl chloride (Chloro-     ................        91          ................
                                methane).                                                                       
78-93-3......................  Methyl ethyl ketone........        78            250000               110        
108-10-1.....................  Methyl isobutyl ketone.....         8             38000                11        
80-62-6......................  Methyl methacrylate........        28            100000                33        
298-00-0.....................  Methyl parathion...........         0.66              6               110        
74-95-3......................  Methylene bromide..........         2             21000                 0.19     
75-09-2......................  Methylene chloride.........  ................       720                 0.053    
86-30-6......................  N-Nitrosodi- phenylamine...  ................      3600                 0.24     
91-20-3......................  Naphthalene................        14            430000                15        
7440-02-0....................  Nickel.....................        11              8600                14        
98-95-3......................  Nitrobenzene...............         0.084           520                 0.11     
152-16-9.....................  Octamethyl- pyrophos-        ................        31                 0.37     
                                phoramide.                                                                      
56-38-2......................  Parathion..................         3                19            160000        
608-93-5.....................  Pentachlorobenzene.........         5          ................  ................
82-68-8......................  Pentachloro- nitrobenzene           0.081      ................  ................
                                (PCNB).                                                                         
87-86-5......................  Pentachlorophenol..........  ................        22                 0.0022   
108-95-2.....................  Phenol.....................        84            390000               110        
298-02-2.....................  Phorate....................         0.11            510          ................
23959-58-5...................  Pronamide..................        21            230000                25        
129-00-0.....................  Pyrene.....................        54             16000                 2        
110-86-1.....................  Pyridine...................         0.16            930                 0.21     
94-59-7......................  Safrole....................  ................        28                 0.0044   
7782-49-2....................  Selenium...................         0.93       ................  ................
7440-22-4....................  Silver.....................       200          ................  ................
95-94-3......................  Tetrachloro- benzene,               0.23           1600                 0.032    
                                1,2,4,5-.                                                                       
630.20-6.....................  Tetrachloro- ethane,         ................       370                 0.042    
                                1,1,1,2-.                                                                       
79-34-5......................  Tetrachloro- ethane,         ................        70                 0.0077   
                                1,1,2,2,-.                                                                      
127-18-4.....................  Tetrachloro- ethylene......         2            100000                 3        
53-90-2......................  Tetrachloro- phenol,                2             35000                 2        
                                2,3,4,6-.                                                                       
7440-28-0....................  Thallium (l)...............  ................        33                 0.071    
108-88-3.....................  Toluene....................        30            560000                51        
76-13-1......................  Trichloro-1,2,2,-                2200          ................     12000        
                                trifluoroethane, 1,1,2-.                                                        
120-82-1.....................  Trichlorobenzene, 1,2,4-...         0.69          62000                 3        
71-55-6......................  Trichloroeth- ane, 1,1,1-..  ................       190                 0.0077   
79-01-6......................  Trichloroeth- ylene........  ................      3200                 0.049    
75-69-4......................  Trichlorofluo- romethane...        48            170000                61        
95-95-4......................  Trichlorophenol, 2,4,5-....        18             55000                22        
88-06-2......................  Trichlorophenol, 2,4,6-....         0.054           160                 0.068    
93-76-5......................  Trichlorophenoxyacetic              2               150                 2        
                                acid, 2,4,5-(245-T).                                                            
93-72-1......................  Triclorophen- oxypropionic          1               520                 2        
                                acid, 2,4,5- (Silvex).                                                          
96-18-4......................  Trichloropro- pane, 1,2,3-.         1             14000                 1        
7440-62-2....................  Vanadium...................        10              2700                13        
1330-20-7....................  Xylenes (total)............        22            710000               700        
7440-66-6....................  Zinc.......................        99             51000               130        
----------------------------------------------------------------------------------------------------------------


                                                                                                
[[Page 66469]]



Sec. 268.71  Associated Management Requirements.

    Waste may meet the standards set out in the Conditional Minimize 
Threat Table as an alternative to the treatment standards in the tables 
to Subpart D of this part or the Minimize Threat Table to subpart F of 
this part only if they are placed in a landfill or a monofill as 
defined in 40 CFR 260.10. Waste that is placed in land application 
units must comply with the minimize threat levels set forth in subpart 
F of this part or the treatment standards set forth in subpart D of 
this part.

[FR Doc. 95-29458 Filed 12-20-95; 8:45 am]
BILLING CODE 6560-50-P