[Federal Register Volume 62, Number 85 (Friday, May 2, 1997)]
[Proposed Rules]
[Pages 24212-24254]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 97-11155]



[[Page 24211]]

_______________________________________________________________________

Part III





Environmental Protection Agency





_______________________________________________________________________



40 CFR Part 60, et al.



Revised Technical Standards for Hazardous Waste Combustion Facilities; 
Proposed Rule

  Federal Register / Vol. 62, No. 85 / Friday, May 2, 1997 / Proposed 
Rules  

[[Page 24212]]


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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Parts 60, 63, 260, 261, 264, 265, 266, 270, and 271

[FRL-5818-9]


Revised Technical Standards for Hazardous Waste Combustion 
Facilities

AGENCY: Environmental Protection Agency (EPA).

ACTION: Notice of data availability and request for comments.

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SUMMARY: This document is a notice of availability and invitation for 
comment on the following information pertaining to the proposed revised 
standards for hazardous waste combustors (61 FR 17358 (April 19, 
1996)): Report on the status of setting national emission standards for 
hazardous air pollutants (NESHAPS) based on the revised emissions 
database; Report on the selection of pollutants and source categories, 
including area and major sources; report on the status of various 
implementation issues, including compliance dates, compliance 
requirements, performance testing, and notification and reporting 
requirements; and report on the status of permit requirements, 
including waste minimization incentives.

DATES: Written comments must be submitted by June 2, 1997.

ADDRESSES: Commenters must send an original and two copies of their 
comments referencing docket number F-97-CS4A-FFFFF to: RCRA Docket 
Information Center, Office of Solid Waste (5305G), U.S. Environmental 
Protection Agency Headquarters (EPA, HQ), 401 M Street, SW., 
Washington, DC 20460. Deliveries of comments should be made to the 
Arlington, Virginia address listed below. Comments may also be 
submitted electronically through the Internet to: rcra-
[email protected]. Comments in electronic format should also be 
identified by the docket number F-97-CS4A-FFFFF. All electronic 
comments must be submitted as an ASCII file avoiding the use of special 
characters and any form of encryption. For other information regarding 
submitting comments electronically or viewing the comments received or 
supporting information, please refer to the proposed rule (61 FR 17358 
(April 19, 1996)).
    Commenters should not submit electronically any confidential 
business information (CBI). An original and two copies of the CBI must 
be submitted under separate cover to: RCRA CBI Document Control 
Officer, Office of Solid Waste (5305W), U.S. EPA, 401 M Street, SW., 
Washington, DC 20460.
    Public comments and supporting materials are available for viewing 
in the RCRA Information Center (RIC), located at Crystal Gateway One, 
1235 Jefferson Davis Highway, First Floor, Arlington, Virginia. The RIC 
is open from 9 a.m. to 4 p.m., Monday through Friday, except for 
Federal holidays. To review docket materials, the public must make an 
appointment by calling 703-603-9230. The public may copy a maximum of 
100 pages from any regulatory docket at no charge. Additional copies 
cost $0.15 per page.

FOR FURTHER INFORMATION CONTACT: For general information, contact the 
RCRA Hotline at 1-800-424-9346 or TDD 1-800-553-7672 (hearing 
impaired). In the Washington metropolitan area, call 703-412-9810 or 
TDD 703-412-3323. The RCRA Hotline is open Monday-Friday, 9 a.m. to 6 
p.m., Eastern Standard Time. The RCRA Hotline can also provide 
directions on how to access electronically some of the documents and 
data referred to in this notice via EPA's Cleanup Information Bulletin 
Board System (CLU-IN). The CLU-IN modem access phone number is 301-589-
8366, or Telnet to clu-in.epa.gov for Internet access. The files posted 
on CLU-IN are in Portable Document Format (PDF) and can be viewed and 
printed using Acrobat Reader.
    For more detailed information on specific aspects of this notice, 
contact Larry Denyer, Office of Solid Waste (5302W), U.S. Environmental 
Protection Agency, 401 M Street, SW., Washington, DC 20460, 703-308-
8770, e-mail address: [email protected].

SUPPLEMENTARY INFORMATION:

    The Agency specifically solicits comment on the following 
documents:
    (1) Draft Technical Support Document for HWC MACT Standards (NODA), 
Volume I: MACT Evaluations Based on Revised Database, April 1997.
    (2) Draft Technical Support Document for HWC MACT Standards (NODA), 
Volume II: Evaluation of CO/HC and DRE Database, April 1997.
    (3) Draft Technical Support Document for HWC MACT Standards (NODA), 
Volume III: Evaluation of Metals Emissions Database to Investigate 
Extrapolation and Interpolation Issues, April 1997.
    In preparing this notice, the Agency considered comments on the 
proposed rule, including those listed below. EPA is soliciting 
responsive comments regarding certain data and information presented in 
these comments:
    (1) Cement Kiln Recycling Coalition
    (2) Chemical Manufacturers Association
    (3) Coalition for Responsible Waste Incineration
    (4) Don Clay Associates
    (5) The Dow Chemical Company
    (6) Environmental Technology Council
    (7) Holnam Inc.
    (8) Lafarge Corporation
    (9) Molten Metal Technology, Inc.
    (10) The Natural Resources Defense Council, Inc.
    (11) Rollins Environmental Services, Inc.
    (12) Safety-Kleen Corp.
    (13) Texas Natural Resource Conservation Commission
    (14) vonRoll/WTI
    Readers should note that only comments about new information 
discussed in this notice will be considered by the Agency. Issues 
related solely to the April 19, 1996 proposed rule and other subsequent 
notices that are not directly affected by the documents or data 
referenced in today's Notice of Data Availability are not open for 
further comment.

Glossary of Acronyms

acfm--Actual Cubic Feet per Minute
ACI--Activated Carbon Injection
APCD--Air Pollution Control Device
BIF--Boiler and Industrial Furnace
BTF--Beyond-the-Floor
CAA--Clean Air Act
CEMS--Continuous Emissions Monitoring System
D/F--Dioxins/Furans
ESP--Electrostatic Precipitator
gr/dscf--Grains per Dry Standard Cubic Foot
HAP--Hazardous Air Pollutant
HC--Hydrocarbons
HWC/HWI--Hazardous Waste Combustor/Incinerator
IWS--Ionizing Wet Scrubber
LVM--Low-volatile Metals
LWAK--Lightweight Aggregate Kiln
MACT--Maximum Achievable Control Technology
MTEC--Maximum Theoretical Emission Concentration
NESHAPs--National Emission Standards for HAPs
NODA--Notice of Data Availability
NPRM--Notice of Proposed Rulemaking
NSPS--New Source Performance Standards
PM--Particulate Matter
RCRA--Resource Conservation and Recovery Act
SRE--System Removal Efficiency
SVM--Semi-volatile Metals
TEQ--Toxic Equivalent
g/dscm--Micrograms per Dry Standard Cubic Meter

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TABLE OF CONTENTS

Part One: Background and Overview of Today's Notice

I. Background
II. Overview of Today's Notice

Part Two: Standards For Hazardous Air Pollutants (NESHAPs)

I. Regulation of Area Sources
    A. Approach to Regulate Area Sources, as Proposed
    B. Positive Area Source Finding for HWCs
    C. Title V Permitting Requirements for Area Sources
II. Revisions to Proposed Standards Using the Revised Emissions 
Database and Data Analysis Methods
    A. Notice of Data Availability on the Revised Emissions Database
    B. PM as a Surrogate for Non-Hg Metals
    C. Options for Controlling Emissions of Organic HAPs
    D. Accounting for Emissions Variability in Establishing Emission 
Standards
    E. Re-Evaluation of Proposed MACT Standards for Incinerators
    F. Re-Evaluation of Proposed MACT Standards for Cement Kilns
    G. Re-Evaluation of Proposed MACT Standards for Lightweight 
Aggregate Kilns

Part Three: Implementation

I. Compliance Date Considerations
    A. Definition of Compliance Date
    B. Pre-Certification of Compliance
    C. Consequences of Non-compliance
II. Compliance Requirements
    A. Compliance with CO and/or HC Emission Standards
    B. Startup, Shutdown, and Malfunction Plans
    C. Metals Extrapolation and Interpolation Considerations
    D. Consideration of Site-Specific Variances for Cement Kilns and 
LWAKs
    E. Emissions Averaging for Cement Kilns
III. DRE Testing Considerations
    A. Options for Ensuring Compliance with a DRE Standard
    B. DRE As a MACT Versus RCRA Standard
IV. Notification and Reporting Requirement Considerations
    A. Public and Regulatory Notification of Intent to Comply
    B. Data Compression Allowances
V. Waste Minimization and Pollution Prevention
    A. Overview
    B. EPA Proposed Flexible Waste Minimization Incentives
    C. Comments Received
    D. Comments Requested on Additional Waste Minimization 
Incentives
VI. Permit Requirements
    A. Coordination of RCRA and CAA Permitting Processes
    B. Permit Process Issues
    C. Omnibus and RCRA/CAA Testing Coordination

Part Four: Miscellaneous Issues

I. 5000 Btu per Pound Policy for Kiln Products
II. Foundry Sand Thermal Reclamation Units
    A. Background
    B. Deferral and Variance Options for Consideration
III. Status of Gaseous Fuels Generated from Hazardous Waste 
Management Activities
IV. Regulatory Flexibility Analysis

Part One: Background and Overview of Today's Notice

I. Background

    On April 19, 1996, EPA proposed revised standards for three source 
categories of hazardous waste combustors (i.e., hazardous waste 
incinerators and hazardous waste-burning cement kilns and lightweight 
aggregate kilns (LWAKs)), 61 FR 17358. After an extension, the comment 
period closed on August 19, 1996.
    The Agency subsequently published two Notices of Data Availability 
(NODA). The first NODA, published on August 23, 1996 (61 FR 43501) 
invited comment on information pertaining to a peer review of three 
aspects of the proposed rule, additional analyses of fuel oils that 
would be used to establish a comparable fuels exclusion, and 
information on a synthesis gas process. The comment period on that NODA 
closed on September 23, 1996. The second NODA, published on January 7, 
1997 (62 FR 960) provided notice and opportunity to comment on an 
updated hazardous waste combustor database containing the emissions and 
ancillary data that the Agency plans to use to develop the final rule. 
The comment period on that NODA closed on February 6, 1997.
    EPA's proposal to revise standards for hazardous waste incinerators 
and hazardous waste-burning cement kilns and LWAKs is under joint 
authority of the Clean Air Act, as amended, (CAA) and the Resource 
Conservation and Recovery Act, as amended (RCRA). The proposed emission 
standards were developed under the CAA provisions concerning the 
maximum level of achievable control over hazardous air pollutants 
(HAPs), taking into consideration the cost of achieving the emission 
reduction, any non-air quality health and environmental impacts, and 
energy requirements. These Maximum Achievable Control Technology (MACT) 
standards, also re ferred to as National Emission Standards for 
Hazardous Air Pollutants (NESHAPs), were proposed for the following 
HAPs: dioxins/furans (D/F), mercury, two semi-volatile metals (lead and 
cadmium), four low volatility metals (antimony, arsenic, beryllium, and 
chromium), particulate matter, and hydrochloric acid/chlorine gas. 
Other toxic organic emissions were addressed by standards for carbon 
monoxide (CO) and hydrocarbons (HC).
    Because of the joint authorities for this rule, the proposal also 
contained an implementation scheme to harmonize the RCRA and CAA 
programs to the maximum extent permissible by law. In pursuing a 
common-sense approach towards this objective, the proposal sought to 
establish a framework that: (1) Provides for combined (or at least 
coordinated) CAA and RCRA permitting of these facilities; (2) allows 
maximum flexibility for regional, state, and local agencies to 
determine which of their resources will be used for permitting, 
compliance, and enforcement efforts; and (3) integrates the monitoring, 
compliance testing, and record keeping requirements of the CAA and RCRA 
so that facilities will be able to avoid two potentially different 
regulatory compliance schemes.

II. Overview of Today's Notice

    The Agency received a large number of public comments in response 
to the proposal. The Agency evaluated the public comments received and 
their applicability to the proposed rule. In those instances where 
comments provided new information or new insights, the Agency has 
reevaluated certain aspects of the proposal based on this new 
information. The Agency is issuing this NODA in an effort to inform the 
public of: (1) Significant changes the Agency is considering on aspects 
of the proposal based on public comments and new information; and (2) 
the Agency's own reevaluation (and to some degree narrowing) of MACT 
standard-setting approaches based on new data and (at least in part) on 
public comments.

Part Two: Standards for Hazardous Air Pollutants (NESHAPs)

I. Regulation of Area Sources

    In this section, we solicit comment on making a positive area 
source finding to subject hazardous waste combustor area sources to the 
same MACT standards that would apply to major sources and on whether, 
under such a finding, area sources should be subject to Title V permit 
requirements.
A. Approach To Regulate Area Sources, as Proposed
    A major source is a source that has the potential to emit 
(considering controls) either 10 tons per year of any hazardous air 
pollutant or 25 tons of any combination of HAPs. Area sources are any 
sources which are not major sources.
    The Agency proposed to subject area sources to MACT standards under 
authority of CAA section 112(c)(6). See 61 FR at 17365. That section 
requires

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the Agency to subject to MACT standards 1 all sources in 
source categories that account for not less than 90 percent of the 
aggregate emissions of each enumerated pollutant. 2 The 
enumerated pollutants emitted by hazardous waste combustors (HWCs) 
include mercury (Hg), D/F, and other polycyclic organic HAPs. The 
Agency explained at proposal that HWCs were significant emitters of D/F 
and Hg, and that much of the human health risk from emissions of HAPs 
from HWCs comes from these high priority HAPs, and D/F in particular.
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    \1\ For area sources, section 112(c)(6) requires the Agency to 
establish either MACT standards under section 112(d)(2), or 
generally available control technology (GACT) standards under 
section 112(d)(5). Given the similarities between major and area 
source HWCs as discussed in subsequent sections of the text, area 
sources should be subject to MACT.
    \2\ Section 112(c)(6) enumerates the following high-priority 
hazardous pollutants for special regulation: alkylated lead 
compounds, polycyclic organic matter, hexachlorobenzene, mercury, 
polychlorinated biphenyls, and 2,3,7,8-tetrachlorodibenzofurans and 
p-dioxin.
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    We received many comments pertaining to this part of the proposal, 
and we will address those comments in the final rule. The area source 
issue is discussed in today's notice because commenters said that 
another, more appropriate reading of section 112(c)(6) is that this 
authority could be used to apply MACT control to area sources only for 
the enumerated HAPs, not the full array of HAPs that the Agency 
proposed to regulate (e.g., particulate matter (PM), semivolatile 
metals (SVM), low volatile metals (LVM)). Nonetheless, were EPA to 
adopt this reading, the Agency continues to believe that area sources 
need to be regulated for this full array of HAPs.
    In light of issues commenters raised, we solicit comment on an 
alternative approach that would subject area sources to all of the MACT 
standards for major sources based on the Agency making a positive area 
source finding.
B. Positive Area Source Finding For HWCs
    Area sources must be regulated by technology-based standards 
3 if the area source category is listed pursuant to section 
112(c)(3) based on the Agency's finding that these sources 
(individually or in the aggregate) present a threat of adverse effects 
to human health or the environment. Such a finding is termed a positive 
area source finding. The Agency is today soliciting comment on whether 
a positive area source finding is appropriate for hazardous waste 
incinerators and hazardous waste burning cement kilns and lightweight 
aggregate kilns.
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    \3\ That is, MACT standards under section 112(d)(2) or GACT 
standards under section 112(d)(5).
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    A positive area source finding would be based on the risk 
assessment performed for the proposed rule and ultimately the final 
rule. Even though the sources modeled in support of the proposed rule 
may have met the definition of a major source, EPA believes their HAP 
emissions, other than HCl, are also representative of area source 
emissions. This is because, as discussed below, these example sources 
may be able to reduce their HCl emissions to become area sources 
without reducing emissions of D/F, Hg, or other metal HAPs that could 
pose significant health risk.4
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    \4\ From a technical perspective related to the nature of common 
air pollution control devices, reducing HCl emissions would not 
generally reduce emissions of other HAPs.
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    Many comments were submitted on the risk assessment methodology 
used to support the proposed rule. We are considering these comments in 
development of the final rule and are making appropriate changes to the 
risk methodology, including modeling additional facilities. These 
changes could affect the Agency's findings for both major and area 
sources. The Agency is not today reopening the comment period on the 
risk assessment.
    1. Risks that could be posed by area source incinerators. We showed 
at proposal that baseline emissions from incinerators could pose high 
end individual lifetime cancer risks from D/F up to 9E-5. See 61 FR at 
17389. In addition, although the risk from low volatile metals (i.e., 
As, Be, Cr, and Sb) was not estimated to exceed 4E-6, the example sites 
modeled were not representative of the short stacks of many on-site 
incinerators. The direct inhalation component of the individual cancer 
risk estimates may increase when incinerators with short stacks are 
included in the risk assessment supporting the final rule.
    2. Risks that could Be posed by area source cement kilns. The 
Agency showed at proposal that baseline emissions from cement kilns 
could pose high end individual lifetime cancer risks from D/F up to 9E-
5. See 61 FR at 17402. Although several high D/F-emitting cement kilns 
have recently reduced their D/F emissions significantly, a revised risk 
assessment may well show that cement kilns (both area and major 
sources) can pose significant health risk at current emission levels.
    3. Risks that could Be posed by area source lightweight aggregate 
kilns. Although the Agency did not show high baseline D/F cancer risks 
for LWAKs at proposal, the risk assessment assumed extremely low D/F 
emissions--0.04 ng TEQ/dscm--based on very limited data from a single 
LWAK. However, as discussed below in section II.G, new data from two 
additional LWAKs show substantially higher emission levels--up to 4.1 
ng TEQ/dscm. At these emission levels, the high end individual lifetime 
cancer risk from D/F could exceed 1E-5.
    4. Basis for a positive area source finding. In evaluating these 
estimated risk levels to determine whether they are sufficient to make 
a positive area source finding, the Agency considered other factors 
which EPA believes to be relevant in determining how to exercise its 
discretion regarding area source determinations for these sources:
    a. HWC area sources can pose the same hazard to human health or the 
environment as major sources. An area source may have the same emission 
rates of HAPs other than hydrogen chloride (HCl, the principal HAP that 
causes a HWC to be a major source) as a major source, and thus pose 
essentially the same hazard to human health or the environment. In 
other words, sources could have HCl emissions low enough to avoid a 
major source classification, but have emissions of D/F that could pose 
a health risk given that there is no direct correlation between HCl and 
D/F emissions.5
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    \5\ For well-designed and operated combustion systems, D/F 
emissions are related primarily to post-combustion particle surface 
catalyzed reactions and the temperature of the combustion gas (the 
optimum temperature window for formation is 450-750  deg.F), 
virtually irrespective of HCl concentrations in the gas.
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    In addition, some HWCs that would currently be classified as major 
sources because of their HCl emissions may be able to lower their HCl 
emissions to become area sources. The Agency projects that all LWAKs 
are currently major sources principally because of their HCl emissions, 
and that approximately 80 percent of cement kilns are major sources, 
again because of HCl. These HWCs may be able to lower their HCl 
emissions to otherwise become area sources.6
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    \6\ Some commercial incinerators may also be able to lower their 
allowable HCl emission levels to become area sources. It could be 
more problematic for on-site incinerators to lower their emissions 
to become area sources because facility-wide HAP emissions must be 
considered when making the major/area source determination. For 
example, on-site incinerators located at large chemical production 
facilities would need to reduce HAP emissions at a large number of 
sources.
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    Sources have until the compliance date of the MACT standards (i.e., 
three years after publication in the Federal

[[Page 24215]]

Register) to make a major source determination. Many kilns spiked 
chlorine in the hazardous waste feed during compliance testing to get 
approval to feed chlorine (and emit HCl/Cl2) at levels ostensibly 
higher than normal. Given that sources ``have the potential to emit'' 
at these ostensibly higher than normal emission rates, these emission 
rates must be used for the major source determination. See CAA section 
112(a)(1), definition of major source. These sources may be able to 
operate successfully at lower allowable chlorine feedrates and emission 
rates, however. If so, they can elect to retest their units and base 
the major/area source determination on potentially lower HCl/Cl2 
emission rates.
    b. RCRA sections 3004(o)(2) and 3004(q) essentially command 
regulation of all HWCs. Under this RCRA mandate, the Agency has 
regulated all (i.e., both major and area sources) hazardous waste 
incinerators since 1981 (see 46 FR 7678 (Jan. 23, 1981) as amended at 
48 FR 14295 (Apr. 1, 1983)) and all hazardous waste burning cement and 
lightweight kilns since 1991 (see 56 FR 7134 (Feb. 21, 1991)). 
Deferring regulation of HWCs to the CAA would not be appropriate unless 
all HWC sources were covered. In addition, although somewhat more than 
half of the commercial incinerators appear to be area sources, the 
majority of on-site incinerators are likely to be major 
sources.7 The public expectation is that all HWCs would 
continue to be regulated.8
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    \7\ Only approximately 30 percent of incinerators appear to be 
major sources. This estimate is based on only the incinerators' 
stack emissions, however. Given that facility-wide emissions of HAPs 
are considered when making a major source determination, many on-
site incinerators are likely to be classified as major sources 
because they are located at large petrochemical facilities.
    \8\ It would be particularly problematic from a RCRA perspective 
for commercial incinerators that are area sources to be exempt from 
MACT standards.
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    c. MACT controls are reasonable and appropriate for both major and 
area sources. The emission control equipment (and where applicable, 
feedrate control) defined as floor or beyond-the-floor (BTF) control 
for each source category is applicable and appropriate to area sources. 
There is nothing unique about the types and concentrations of emissions 
of HAPs from area sources versus major sources that would make MACT 
inappropriate for an area source.
    d. Area source HWCs contribute significantly to D/F and Hg 
emissions. Both area and major source HWCs contribute significantly to 
aggregate emissions of D/F and Hg, two high priority HAPs. See CAA 
section 112(c)(6) and proposal discussion at 61 FR at 17366.
    For these reasons, the Agency is taking comment on making positive 
area source findings for each of the three source categories covered by 
the proposal. Again, the effect would be to subject all sources within 
these categories to MACT standards, which also would be the effect of 
the original proposal.

C. Title V Permitting Requirements for Area Sources

    Under Sec. 63.1(c)(2), area sources subject to MACT (or GACT) are 
subject to the requirement to obtain a Title V permit unless the 
standard for the source category (e.g., Subpart EEE for HWCs) specifies 
that: (1) States will have the option to exclude area sources from 
Title V permit requirements; or (2) States will have the option to 
defer permitting of area sources. The Agency has determined that if it 
makes a positive area source finding and subjects area sources to MACT 
standards as discussed above, the Agency would also consider subjecting 
area sources immediately to Title V permitting requirements, as 
provided by Sec. 63.1(c)(2)(iii). The Agency has determined that area 
source compliance with Title V permit requirements would not be 
``impracticable, infeasible, or unnecessarily burdensome''. See CAA 
section 502(a). As noted above, area sources can be virtually identical 
to major sources with respect to size, type of combustor, and 
commercial versus on-site status, except that their mass emissions of 
HCl are lower. Thus, waiver of Title V permitting would not be 
warranted.
    In addition, if the Agency were to waive the Title V permit 
requirement for area sources, we would be concerned about the confusion 
it would likely create for the regulated community and the public if 
the air emissions standards for some hazardous waste combustors (even 
in the same source category) were addressed in the Title V permitting 
process and the air emissions standards for others were addressed in 
the RCRA permitting process. Since a source can make modifications to 
their emissions levels that could change their major/area source 
determination, a source could move from one permitting program to the 
other, creating difficulties for the permitting agencies in tracking 
sources and for the public in trying to participate in or follow the 
permitting process. Therefore, it appears most appropriate from an 
implementation standpoint to subject area sources to Title V 
permitting. In this way, all HWCs (both major and area sources) would 
be subject to the same Title V permitting requirements.

II. Revisions to Proposed Standards Using the Revised Emissions 
Database and Data Analysis Methods.

    In this section, the Agency discusses comments on the revised 
emissions database and the revised standards that would result from 
applying an engineering evaluation and data analysis methods to that 
revised database. In addition, we discuss several issues that are 
generic to the MACT standards for all three source categories: (1) 
Consideration of PM as a surrogate for non-Hg metal HAPs; (2) options 
for controlling emissions of organic HAPs; and (3) emissions 
variability.
A. Notice of Data Availability on the Revised Emissions Database
    On January 7, 1997 the Agency published a NODA on an updated 
database of emissions and ancillary information. See 62 FR 960. The 
Agency updated the database used at proposal to correct errors and 
include additional emissions data. The NODA explained that the updated 
database would be used to identify MACT standards for the final rule 
and to evaluate economic impacts and, for RCRA purposes, risks 
associated with the final MACT standards.
    The Agency received comments on the revised database from 16 
stakeholders representing the cement industry, lightweight aggregate 
industry, and on-site and commercial incinerators. The database was 
revised again to accommodate the comments received on the database 
NODA. The Agency then re-analyzed the database to determine the MACT 
floor standards discussed below.
    We received several specific comments (i.e., as opposed to generic 
and undocumented comments that, for example, the Agency's data are 
inconsistent with the commenter's) that were not accompanied with 
supporting documentation. Most of these comments pertain to 
miscellaneous data on feedstream feedrates and equipment design 
information that do not have a significant impact on developing MACT 
floor standards under the data analysis methods discussed in today's 
NODA. Where there was a significant possibility that the data might 
affect the Agency's determinations, references were re-checked to 
determine the more accurate number to be used.
    The Cement Kiln Recycling Coalition (CKRC) provided an extensive 
run-by-run, HAP-by-HAP comparison of the Agency's database with theirs. 
While

[[Page 24216]]

potentially useful in some cases, their submission unfortunately did 
not distinguish between significant versus insignificant differences; 
nor did they verify which data were more accurate for the purposes in 
question. Within current time constraints, the Agency has identified 
which appear to us to be significant and relevant differences and then 
checked these data to determine which appear to be more accurate and 
has made necessary changes. The current database, as updated and 
revised, is appropriate and sufficient considering the engineering and 
data analysis methods discussed below to identify MACT standards. For 
example, although there may still remain differences between CKRC's and 
the Agency's database regarding electrostatic precipitator (ESP) and 
fabric filter design and performance characteristics, those 
characteristics are not germane to the engineering and data analysis 
methods for determining relevant MACT standards, as discussed below. In 
these situations, the Agency has elected not to revise inconsequential 
data, particularly where it is not clear which data are more accurate.
    Some overall decisions on data quality issues have also been made 
for purposes of revising the database. Regarding assigning values to 
reported nondetects, we are assuming that nondetected values were 
present at one-half the detection limit. We considered assuming 
nondetected values were present at the full detection limit, but found 
in most cases no significant difference in the MACT data analysis 
results. It represents a judgment by the Agency based on its experience 
that, for assessing standards and risk, this more conservative approach 
increases our confidence that standards and risk are appropriate and 
acceptable.
    In addition, we are excluding data from sources no longer burning 
hazardous waste, as suggested by several commenters on the proposed 
rule. Although such data may well be indicative of the capabilities of 
control equipment and thus relevant, the resulting database is still 
large enough to ensure that potential final MACT standards can be 
judged to be achievable (or not as the case may be) without including 
these more controversial data. Regarding older emissions data when more 
recent data was available for a source, we are considering all data 
sets for sources that currently burn hazardous waste. Both recent and 
old data are instructive in assessing the capabilities of the control 
equipment at these operating facilities.
    Finally, we screened out so-called ``normal'' emissions data from 
the MACT analyses. Although doing so may appear counterintuitive at 
first blush, one must consider that facility compliance will generally 
be based on operating limits established during the MACT performance 
test (except if compliance is based on a continuous emissions 
monitoring system (CEMS)). During these MACT performance tests, sources 
will likely operate under the same worst-case conditions as they did 
during trial burns and Boiler and Industrial Furnace (BIF) rule 
certification of compliance testing. Operating under worst-case 
conditions with respect to emissions and operating parameters gives 
operators a wide allowable envelope of operating limits needed to 
efficiently and economically operate the combustor and yet maintain 
compliance. Considering normal emissions data in the MACT analysis 
could inappropriately result in the Agency establishing a MACT standard 
based on normal emissions and conditions while the source would be 
operating under worst-case conditions to demonstrate compliance. Thus, 
emissions while complying with operating limits would be 
inappropriately constrained to below current normal emission levels, 
even for sources equipped with well-designed and operated MACT floor 
control.
B. PM as a Surrogate for Non-Hg Metals
    The Agency proposed a MACT PM standard as a surrogate for non-D/F 
organic HAPs (that are adsorbed onto the PM) and for the metal HAPs not 
individually regulated under the proposed metal standards (i.e., Co, 
Mn, Ni, and Se). See 61 FR at 17376.
    Since proposal, the Agency has reconsidered in the context of this 
joint RCRA-CAA rulemaking whether a MACT PM emission standard could 
serve as a surrogate for six non-Hg metal HAPs for which the Agency did 
propose specific standards--semivolatiles (Cd and Pb) and low volatiles 
(As, Be, Cr, and Sb). This issue arises, in part, because the risk 
assessment at proposal on the MACT standards estimated that the high-
end individual lifetime cancer risks using 90th percentile metal 
emission levels were well below 10-6 for cement kilns and 
LWAKs. For incinerators, the highest estimated cancer risks exceeded 
10-6 but were below 10-5.\9\
---------------------------------------------------------------------------

    \9\ Note, however, that the example incinerators modeled for the 
risk assessment had relatively tall stacks which may not result in 
the higher ground level concentrations (and thus higher direct 
inhalation risk) that could result from small incinerators.
---------------------------------------------------------------------------

    To evaluate PM as a surrogate for non-Hg metals in the context of 
this joint RCRA-CAA rulemaking, questions that must be addressed are: 
(1) Would a MACT PM standard control the six non-Hg metals to MACT 
emission levels in the special context of hazardous waste combustors; 
and (2) would there be significant health risk at MACT emission levels 
that would have to be addressed with RCRA controls (based at least in 
part on site-specific risk assessments using omnibus authority)?
    Because, in the case of hazardous waste combustors, there are 
significant levels of metals in the hazardous waste-derived fuel being 
burned, the Agency has initially concluded that a MACT PM emission 
standard in this particular rule may not adequately control the six 
non-Hg metals to the nominal MACT emission levels. The residual risk 
that could result from emissions of some of the six non-Hg metals could 
be significant 10, and regulation of these problematic 
metals under RCRA would therefore be warranted. From an implementation 
standpoint, this result of mixed statutory controls is not desirable. 
Although establishing six additional specific limits on the non-Hg 
metals eliminates this particular implementation disadvantage, this 
would add to the compliance and implementation burdens on facility and 
regulator alike. Consequently, it does not currently appear appropriate 
to use PM as a surrogate for all six toxic, non-Hg metals.
---------------------------------------------------------------------------

    \10\  This is at least partly because a PM control device alone 
does not give the same targeted degree of control for individual 
metals that a combination of metal feed control plus a PM control 
device does.
---------------------------------------------------------------------------

    In investigating this issue, however, we determined that antimony 
(Sb), one of the four low volatile metals, may not warrant direct 
control. That is, the MACT PM standard may serve as an adequate 
surrogate for Sb to ensure that it is not emitted at levels that pose a 
health risk. 11 We also considered whether beryllium (Be), 
another LVM, warranted control given that it is not generally present 
in significant concentrations in hazardous waste, and baseline 
emissions of Be do not appear to be posing a health hazard. Given that 
Be is a toxic carcinogen, however, direct MACT controls should be 
provided even if current feedrates (and emission rates) are low.
---------------------------------------------------------------------------

    \11\  Sb is a non-carcinogen with relatively low toxicity 
compared with the other five non-Hg metals, and would have to be 
present in hazardous waste (and emitted PM) at extremely high levels 
(perhaps over 1000 times the current levels) to pose a health 
hazard. Current data suggest that metals feedrates generally are 
either not increasing or increasing at much lower rates.
---------------------------------------------------------------------------

    Only a preliminary analysis (see discussion below) was used to 
investigate whether some of the

[[Page 24217]]

remaining semivolatile and low volatile metals--Cd, Pb, As, and Cr--may 
warrant only indirect control through a PM standard for any or all of 
the HWC source categories. We continue to believe that direct standards 
are warranted for these four metals (either individually or in 
volatility groups). For purposes of public comment, we have identified 
MACT standards for these individual metals in case individual standards 
are ultimately deemed more appropriate than continuing to group the 
metals by relative volatility. However, we remain concerned about the 
compliance and implementation complexities that would be introduced. 
(See the discussion below of revised SVM and LVM standards for each 
source category.)
    We solicit further comment on how to ensure appropriate and 
effective control of non-Hg metal HAPs while ensuring that the 
regulatory scheme and associated compliance elements are implementable 
and not unnecessarily burdensome. Some of the pertinent issues are 
highlighted below for commenter response.
    1. Can PM serve as a surrogate for SVM and LVM? A MACT PM standard 
would provide MACT emissions control technology (i.e., the air 
pollution control device) for non-Hg metals. This is because stack 
emissions of non-Hg metals in combustion gases are controlled by the PM 
control device. Thus, MACT control (i.e., the emission control device) 
for PM would also be MACT control for non-Hg metals.
    However, emissions of non-Hg metals from HWCs are also controlled 
by the feedrate of non-Hg metals (for kilns, the feedrate of non-Hg 
metals in hazardous waste) in addition to the PM control device. Thus, 
a MACT PM standard alone may not result in control of non-Hg metals to 
MACT emissions levels because emissions of non-Hg metals will vary at a 
given PM level as feedrate varies (i.e., emissions of non-Hg metals 
will be a greater percentage of PM emitted as the feedrate rises).
    Some commenters have argued that PM is not a good surrogate for 
non-Hg metals emissions. When sources (within a source category) are 
considered in the aggregate, a poor correlation between PM and non-Hg 
metals emissions appears to exist. This is because sources have various 
feedrates of the metals and because different types of PM control 
devices have different collection efficiencies for these metals.\12\. 
\13\ Nonetheless, at a given source with a given non-Hg metal feedrate, 
metal emissions will correlate with PM emission levels. Although the 
correlation will be different for more volatile versus less volatile 
metals, emissions of these metals will increase as PM emissions 
increase.
---------------------------------------------------------------------------

    \12\ In addition, metal collection efficiency of the PM control 
device varies at different metal feedrates.
    \13\ See, for example, comments submitted by Chemical 
Manufacturers Association, RCRA Docket # F-96-RCSP-FFFFF comment # 
RCSP-00128.
---------------------------------------------------------------------------

    In summary, although there is a correlation between PM and non-Hg 
metal emissions on a facility-specific basis, and the MACT PM standard 
likely would ensure use of MACT emission control device for these 
metals, it may not ensure attainment of MACT emission levels of these 
metals. Given the potential for HWCs to emit high levels of some of 
these metals, metal-specific emission controls--MACT standards--are 
warranted either individually or in volatility groups.
    2. Which non-Hg metals warrant specific control by establishing 
MACT emission standards? As an alternative to establishing MACT 
standards for SVM and LVM as proposed, we are re-evaluating which non-
Hg metals warrant special control and whether to establish individual 
MACT emission standards for them. 14 As discussed above, our 
preliminary analysis indicates that standards may not be warranted for 
Sb. We are continuing to investigate whether any of the remaining 
metals--As, Be, Cd, Cr, and Pb--may not warrant direct emission 
standards but may warrant only indirect controls via the PM standard. 
Further, we are investigating how the metal standards should be 
structured: (1) MACT standards for individual metals; or (2) MACT 
standards for volatility groupings (SVM and LVM) if we determine, as 
currently contemplated, that direct standards for all five remaining 
metals are warranted (i.e., as proposed).
---------------------------------------------------------------------------

    \14\  Other metal HAPs (other than Hg and the six toxic metals 
covered at proposal) would be controlled indirectly by the PM 
standard and any individual or volatility group metal standards. 
This is essentially unchanged from the proposal.
---------------------------------------------------------------------------

    For cement kilns and LWAKs, we examined a comparison of potentially 
allowable emission levels for non-Hg metals under the BIF rule and 
actual allowable (i.e., levels emitted during Certificate of Compliance 
(CoC) testing) emission levels. (Note that the actual allowable levels 
are generally much higher than normal emission levels because sources 
spiked metals during CoC testing.) A wide margin exists--generally an 
order of magnitude or greater--between BIF potentially allowable 
emission levels and CoC allowable emission levels. This means that: (1) 
Cement kilns and LWAKs are not emitting these metals at levels posing a 
risk using BIF risk assessment procedures; and (2) cement kilns and 
LWAKs are feeding these metals at rates well below those that would be 
allowed under BIF risk-based limits and, thus, indirect PM control 
under MACT may similarly keep feedrates (and emission rates) of these 
metals low.
    We also examined data on the percentage of emitted particulate 
matter that each non-Hg metal would have to comprise to pose a health 
risk, assuming BIF risk assessment procedures were applied. Under this 
analysis, Pb and Sb would have to comprise from 10-100 percent of 
emitted PM to pose a health risk. Data suggest that these percentages 
are not approached in today's operations by a wide margin.
    These preliminary analyses were performed assuming BIF risk 
assessment procedures. Thus, our evaluation may not be representative 
of results that will be forthcoming shortly using updated, more 
detailed procedures for evaluating risks under the final MACT 
standards. For example, the risk assessment for this rule considers 
indirect exposure (i.e., ingestion and food-chain uptake) while BIF 
procedures consider only direct inhalation. On the other hand, BIF 
direct inhalation exposure assessment procedures are more conservative 
(i.e., result in a higher estimate of risk) than those that will be 
used for the final MACT standards because the Agency has revised those 
procedures in part to consider more realistic exposure scenarios. 
Nonetheless, the analyses discussed above are viewed as suggestive that 
regulation of each and every semivolatile and low volatile metal as 
proposed may not be warranted.
    We could not perform similar preliminary analyses for incinerators 
because we do not have dispersion coefficients readily available that 
would be representative of the short stacks used by many on-site 
incinerators. However, a review of the emissions database indicates 
that, as expected, some incinerators--both commercial and on-site 
incinerators--emit much higher levels of these metals than cement kilns 
or LWAKs. Nonetheless, we may find (as may be the case for cement kilns 
and LWAKs) that Sb may not warrant a direct metal-specific standard for 
incinerators as well, either as part of the LVM group or an individual 
standard.

[[Page 24218]]

C. Options for Controlling Emissions of Organic HAPs
    Based on evaluation of the revised emissions database, the Agency 
is soliciting comment on options to control emissions of organic HAPs 
by: (1) Establishing MACT standards for carbon monoxide (CO) and/or HC 
emissions as surrogate indicators of good combustion conditions; 
15 and (2) ensuring that sources achieve 99.99 percent 
destruction and removal efficiency (DRE).16 These options 
are presented in Part Three: Implementation, Sections II and III, 
because the DRE issue has implementation implications, and the CO/HC 
issue relates to the DRE issue.
---------------------------------------------------------------------------

    \15\ The Agency proposed to establish MACT standards for both CO 
and HC, but solicited comment on whether a standard based on one 
surrogate or the other may be sufficient. See 61 FR at 17376.
    \16\ The Agency proposed to retain DRE as a RCRA standard 
because of concerns that it would be difficult to self-implement 
under MACT implementation procedures. See 61 FR at 17447. The Agency 
is reconsidering this issue and solicits comment on alternative 
approaches to ensure compliance with the DRE standard, including 
incorporating DRE as a MACT standard.
---------------------------------------------------------------------------

D. Accounting for Emissions Variability in Establishing Emission 
Standards
    At proposal, the Agency used a statistical approach to identify an 
emission level that MACT floor control could achieve routinely 
considering that the emissions database was comprised of ``short-term'' 
test data. See 61 FR at 17366. To identify an appropriate standard, a 
computed variability factor considering within-test condition emissions 
variability was added to the log-mean of the highest test condition 
average for any source using floor control. The log-mean of the runs 
for the standard-setting test condition is the ``design level'--the 
emission level the source would be designed to meet to ensure emissions 
were less than the standard 99 percent of the time, assuming a source 
had average within-test condition emissions variability (average based 
on all sources using floor control).
    We are concerned that this computed variability factor approach may 
be inappropriate in this particular rulemaking.17 For 
example, this computed variability factor led to illogical results for 
the PM standards for incinerators and LWAKs. In the case of PM, the 
calculated standard using the computed variability factor is 50 percent 
higher than the current legally-mandated RCRA PM limit for 
incinerators. For LWAKs, using the variability factor results in a PM 
standard of approximately 0.04 gr/dscf (corresponding to a design level 
of 0.022 gr/dscf) nearly twice as high as any PM emission value in the 
entire LWAK database. Further, given that floor control would be a 
fabric filter, our engineering evaluation 18 (and the LWAK 
database itself) indicates that a fabric filter can readily achieve 
levels of 0.022 or below, not the calculated 0.04.
---------------------------------------------------------------------------

    \17\ See, for example, proposed rule (61 FR at 17367).
    \18\ See USEPA, ``Draft Technical Support Document for HWC MACT 
Standards (NODA), Volume I: MACT Evaluations Based on Revised 
Database'', April 1997.
---------------------------------------------------------------------------

    These inappropriate and illogical results may flow from either the 
variability factor itself or the test condition average identified as 
the standard-setting test condition (to which the variability factor is 
added). For example, the variability factor itself (which considers 
within-test conditions emissions variability) could be inappropriately 
high if there are outlier runs within test conditions that are not 
screened out. Although runs in many test conditions appear to be 
outliers (and analytical tests may show them to be outliers) it can be 
difficult to justify screening them out unless there is a specific 
technical explanation (e.g., unique design or operation feature or 
inadequacy) that can be identified. Unfortunately, this information is 
often not available for many potential outlier data.
    As noted, identifying the standard-setting test condition 
inappropriately could be a factor. We have very limited information on 
the design, operation, and maintenance characteristics of the emission 
control devices and combustors. Accordingly, we have had to define MACT 
floor control very generically (e.g., ESP or fabric filter), as 
discussed below, without attempting to specify design, operation, and 
maintenance characteristics.
    Given these concerns and the statute's direction to establish the 
maximum but achievable floor standard, we request comment on an 
alternative approach to account for emissions variability. This 
alternative has two elements. First, when a large data set from sources 
using floor control 19 exists, the range of emission levels 
from those sources should adequately reflect emissions variability. 
That is, a standard established as the highest test condition average 
for sources using floor control represents an emission level that the 
control technology is capable of achieving, considering normal 
variability in combustor operations, emission control device 
operations, and test methods. Where these data show that many sources 
using floor control can achieve well below the standard, this 
demonstrates that additional emissions variability considerations are 
not warranted. Source(s) with emission levels close to the standard 
should be able to determine how to emit at levels below the standard 
based on the specific design, operation, and maintenance information 
available to them, especially since many other sources with the same 
basic equipment are doing so.20 Second, where only a small 
set of data from sources using floor control exists, the range of 
emission levels from these sources may be less likely to reflect 
emissions variability. In this case, consideration of an additional 
variability factor (to be added to the highest test condition average 
for a MACT-control facility) may be appropriate.
---------------------------------------------------------------------------

    \19\ Or, in the case of LWAKs, where the data set is essentially 
complete (i.e., where we have data from all or most of the sources 
in the source category).
    \20\ No patterns in process design or operation in the 
information we have explain why some sources thought to be using 
floor control had significantly higher emissions than other sources 
thought to be using floor control. Where floor control is based on 
an emission control device, these high emitters are likely not in 
fact using floor controls--considering the suite of design, 
operation, and maintenance factors that affect performance of the 
control equipment but on which the Agency has no data. Where floor 
control is based on finite control such as combustion gas 
temperature or feedrate control, the high emitters may be 
experiencing emissions during the compliance test on the high end of 
the range of emissions variability.
---------------------------------------------------------------------------

    The impact of this alternative approach has been examined. We do 
not have a large data set in the expanded universe for two standards: 
D/F standards for incinerators equipped with waste heat recovery 
boilers and D/F standards for LWAKs. In each case, we have data from 
only three sources, and consequently floor control is based on the 
suite of controls used by all three sources.21 If the data 
set were large, we would identify the floor level as the test condition 
with the highest run average. But, given the small data set, it is 
reasonable from an engineering vantage point to identify the standard 
as the highest single run for the highest test condition (when the unit 
was properly operated).
---------------------------------------------------------------------------

    \21\ When data are available from fewer than 30 sources, MACT 
floor is defined as the median emission limitation achieved by the 
best five performing sources. Thus, the best performing three 
sources (representing the median (and better performers)) define 
MACT in this case.
---------------------------------------------------------------------------

    We discuss below engineering and data analysis methods and the 
resulting standards for each HAP and source category where a computed 
variability factor is not used to establish emission standards.

[[Page 24219]]

    Finally, we are using an engineering evaluation to identify a 
design level for each standard for purposes of estimating economic 
impacts and, for RCRA purposes, the risk associated with the design 
level for a given MACT standard. The design level is the emission level 
to which the control equipment must be designed to ensure compliance 
with the standard. For the RCRA risk analysis of the final MACT 
standards, we will analyze risks under the more realistic assumption 
that a source is emitting at the design level on average, rather than 
right at the standard all of the time.
    Based on discussions with several air pollution control device 
vendors and facility operators, a design level of 70 percent of the 
standard is deemed appropriate because it is within the range of 
reasonable values that may be encountered--50 percent to 90 percent. To 
the extent that industry engineering experience suggest that a 
different design level assumption would be more typical and reasonable, 
we invite commenters to provide that information.
    We also considered whether the design level as a percentage of the 
standard (i.e., design factor) should vary depending on whether the 
control is finite (e.g., temperature control or feedrate control) 
versus an emission control device that is affected by various 
parameters, or the type of emission control device (e.g., metals 
controlled by feedrate and an ESP or fabric filter). However, we do not 
have enough information to establish such tailored and case-specific 
design factors. If commenters supply sufficient information, we will 
consider using this approach.
    As noted, we will use the design factor to estimate costs of 
retrofitting for all sources with emissions exceeding the standard. For 
these sources, we will estimate the costs of upgrading emission control 
equipment to meet the design level. For sources using floor control 
(i.e., sources in the expanded universe) that have emissions greater 
than the design level, however, we will not attribute retrofit costs 
for compliance. Given that these sources are using floor control and 
that, as discussed above, the large data set of sources using floor 
control and meeting the floor standard amply accounts for emissions 
variability, we will presume that these relatively high emissions for 
such floor-controlled sources represent the high end of the range of 
emissions variability. In other words, when these sources retest 
emissions under the same conditions, their emissions should meet the 
standard.
E. Re-Evaluation of Proposed MACT Standards for Incinerators
    We discuss in this section the basis for the revised standards for 
incinerators that result from applying engineering and data analysis to 
the revised emissions database. We also discuss refinements to 
analytical approaches used in the proposal for identifying floor 
controls and levels.22 A comparison of the originally 
proposed and potentially revised standards for existing and new sources 
is presented in the table below:
---------------------------------------------------------------------------

    \22\ Additional details of the engineering and data analysis 
evaluations performed on the revised emissions database can be found 
in the Agency's background document: USEPA, ``Draft Technical 
Support Document for HWC MACT Standards (NODA), Volume I: MACT 
Evaluations Based on Revised Database'', April 1997.

                      Table II.E.--Revised Standards for Existing and New Incinerators \1\                      
----------------------------------------------------------------------------------------------------------------
                                                               Existing sources               New sources       
                                                         -------------------------------------------------------
                  HAP or HAP surrogate                      Proposed       Revised      Proposed       Revised  
                                                            standard      standard      standard      standard  
----------------------------------------------------------------------------------------------------------------
D/F (ng TEQ/dscm).......................................         0.20          0.20          0.20          0.20 
Hg (g/dscm)....................................        50            40            50            40    
PM (gr/dscf)............................................         0.030         0.015         0.030         0.015
HCl/Cl2 (ppmv)..........................................       280            75            67            75    
CO (ppmv)...............................................       100           100           100           100    
HC (ppmv)...............................................        12            10            12            10    
SVM (g/dscm)...................................       270           100            62           100    
LVM (g/dscm)...................................       210            55            60           55     
----------------------------------------------------------------------------------------------------------------
\1\ All emission levels are corrected to 7% O2.                                                                 

    1. Subcategorization considerations. Since proposal, the Agency has 
refined potential options for subdividing the incinerator source 
category to determine if subdivided standards would be appropriate: (1) 
Small \23\ versus large sources; (2) commercial versus on-site sources; 
and (3) small on-site sources versus large on-site and commercial 
sources. In large part, commenters believed that small, on-site 
incinerators should have less stringent standards to reduce costs of 
compliance. However, given that our analysis shows that the revised 
standards for the small on-site sources would either remain the same or 
be more stringent under these options, we continue to believe that 
subdividing would be inappropriate.\24\
---------------------------------------------------------------------------

    \23\ An analysis of gas flowrates in actual cubic feet per 
minute (ACFM) indicated that a maximum flowrate of 20,000 acfm would 
be within the range of values that could be selected to designate 
small versus medium incinerators. We performed a similar analysis at 
proposal and selected a flowrate of 23,127 to designate small 
incinerators. See 61 FR at 17372.
    \24\ The Agency requested at proposal comments on other means of 
reducing costs to small, on-site incinerators (e.g., waiving 
requirements for CEMS). We will consider all submitted comments on 
options to reduce costs on these units in the final rule.
---------------------------------------------------------------------------

    We also received comments from the US Department of Energy (DOE) 
suggesting that DOE's mixed waste \25\ incinerators had several unique 
features (discussed below) that would warrant subcategorization.\26\ We 
are investigating whether DOE's incinerators pose unique implementation 
and compliance problems and therefore are considering several options 
for the final rule: (1) no subcategorization; (2) subcategorization for 
mixed waste incinerators; and (3) deferral of MACT regulation for mixed 
waste incinerators (with RCRA rules continuing to apply).
---------------------------------------------------------------------------

    \25\ Mixture of low level radioactive waste and hazardous waste.
    \26\ See summary of DOE/EPA meeting at RCRA Docket # F-96-RCSP-
FFFFF item # S00270.
---------------------------------------------------------------------------

    Under the No Subcategorization Option, we would find that the MACT 
controls and emission standards applicable to other incinerators are 
appropriate for DOE's mixed waste incinerators. Under this option we 
could still define special compliance requirements that account for any 
unique features of mixed waste incinerators.

[[Page 24220]]

    Under the Subcategorization Option, we would find that because of 
unique design or operating features, the MACT controls or emission 
standards identified for other incinerators are not appropriate for 
mixed waste incinerators. MACT standards unique to these incinerators 
would be developed, and special compliance requirements could be 
defined.
    Under the Deferral Option, we would determine that we do not have 
the resources to make an appropriate MACT determination on mixed waste 
incinerators in time to meet the schedule for the HWC rulemaking (i.e., 
the Phase I rule establishing MACT standards for incinerators, cement 
kilns, and LWAKs). Regulation of mixed waste incinerators would be 
deferred to the Phase II rule where the Agency will establish MACT 
standards for hazardous waste burning boilers, halogen acid furnaces, 
and sulfur recovery furnaces. The RCRA rules which now apply would 
continue to do so.
    DOE suggests that its mixed waste incinerators have several unique 
features that would require subcategorization and special compliance 
standards:
     Each of DOE's four conventional incinerators meet the 
Agency's definition of small incinerators (i.e., <20,000 acfm gas flow 
rate), and one is batch-operated only once or twice a year with a gas 
flow rate of 3,000 acfm.
     Several mixed waste thermal treatment units meeting the 
Agency's definition of an incinerator are small vitrification devices 
designed to process metal bearing wastes and feed wastes with extremely 
low organic content.
     Given that most of the mixed waste incinerators are very 
small units, a mass-based emission limit would be more appropriate than 
a concentration-based emission limit.
     Approximately 95 percent of the mixed waste that is 
incinerated is ``legacy waste'' generated during production of nuclear 
weapons from 1943 until 1989 and may contain high levels of mercury 
that cannot be lowered by source reduction.
     Control of mercury emissions using activated carbon 
injection (ACI) would be problematic because the spent carbon would be 
a mixed waste, and if it contained more than 260 ppm of mercury, 
mercury retorting would be required under the Agency's land disposal 
restrictions even though there are no retorters in the country that 
manage mixed waste (and so a variance would have to be obtained under 
Sec. 268.44).
     Given that CEMS are not yet demonstrated for multi-metals 
(and a CEMS requirement for mercury alone is also problematic for the 
final Phase I rule), compliance with MACT metal emission limits would 
be based on feedrate limits for metals in feedstreams, a potentially 
unworkable approach for mixed waste since sampling and analysis of 
radioactive feedstreams raises serious human health concerns.
     DOE has negotiated plans and agreements with States under 
Site Cleanup Agreements mandated by RCRA section 3021(b) and CERCLA 
section 120(e), and such plans and agreements would probably require 
renegotiation (and delay) to comply with the proposed MACT standards.
    The Agency is continuing to investigate these issues and will make 
a determination regarding the appropriate regulatory option in the 
final rule.
    2. Dioxins and Furans (D/F) a. MACT floor for existing sources. We 
proposed a MACT floor standard of ``0.20 ng TEQ/dscm or gas temperature 
at the PM control device 400 deg.F'' based on floor control 
of temperature at the PM control device. During subsequent analysis of 
the revised database, we noticed again that incinerators equipped with 
waste heat boilers have significantly higher D/F emissions than other 
incinerators. This is likely because the heat recovery boiler precludes 
rapid temperature quench of combustion gases to a temperature of 
400 deg.F (usually with a wet scrubber), which would be 
floor control for non-waste heat boilers. Floor control for waste heat 
boilers would be rapid quench of combustion gases at the exit of the 
boiler to a temperature of 400 deg.F.
    Based on the revised database, the floor standard for waste heat 
boilers would be ``0.20, or 12 ng TEQ/dscm and a temperature of 
400 deg.F at the PM control device.'' Given that the waste 
heat boiler expanded universe (i.e., the entire database) is comprised 
of only three sources, the highest single run for the test condition 
with the highest run average is a reasonable floor level. (Note that if 
this were a large data set, we would define the floor level simply as 
the highest test condition average.) This floor level is 50 percent 
higher than the highest test condition average, and thus appears to be 
a level that waste heat boilers should be able to meet routinely using 
floor control.
    The floor standard for non-waste heat boilers would be ``0.20, or 
0.40 ng TEQ/dscm and a temperature of 400 deg.F at the PM 
control device.'' This standard is based on arraying emission levels 
for sources using floor control and screening out four test conditions 
with anomalously high emissions. Three of these test conditions were 
from sources for which we had other test conditions with emissions 
averages well below 0.40 ng TEQ.
    We did not originally propose separate standards for waste heat 
boilers because the floor standard at proposal was ``0.20 ng TEQ/dscm 
or temperature at the PM control device of <400 deg.F.'' Waste heat 
boilers could meet that standard, and moreover, we proposed a BTF 
standard of 0.20 ng TEQ/dscm for all incinerators (a preference we do 
not depart from in today's notice). Today, however, we are presenting 
the option of stating the standard in the form of a TEQ level combined 
with a maximum temperature at the PM control device. This form of the 
standard is consistent with the revised data, and would result in 
somewhat lower emissions. This is because, without the TEQ limit, some 
sources could exceed that TEQ level at the specified temperature.
    b. BTF considerations for existing sources. Incinerators can be 
equipped with ACI at temperatures 400  deg.F to achieve D/F 
levels below 0.20 ng TEQ/dscm. Given the limited application of the 
technology to control D/F emissions from hazardous waste incinerators 
and given that control efficiency is likely to decrease at D/F emission 
levels below 0.20, a BTF standard of 0.20 ng TEQ/dscm would continue to 
be appropriate. See proposal for extended discussion, 61 FR at 17382.
    Another option arising from the refinement of our original analysis 
is to establish a BTF standard for waste heat boilers at ``0.20, or 
0.40 ng TEQ/dscm and a temperature of 400  deg.F at the PM 
control device'', and to remain at the floor standard for non-waste 
heat boilers. These standards would ensure that most, but not all, 
sources would have emissions 0.20 ng TEQ/dscm. Given that 
only a few sources would need to take additional measures to get their 
emissions below 0.20, however, it would be appropriate to establish a 
0.20 BTF standard, assuming this level remains appropriate after 
considering statutory factors for establishing standards more stringent 
than the floor.
    c. MACT floor for new sources. At proposal, we identified the same 
floor control for new sources as for existing sources: wet scrubbing 
and 400  deg.F at the PM device. This is because the sources 
with the lowest emissions used this control. In re-evaluating the 
database for this NODA, however, an engineering evaluation may be more 
appropriate to identify ACI as floor control because one source (i.e., 
the single best controlled source) uses it. Even though most sources 
using rapid quench by wet scrubbing can achieve D/F levels less than 
0.20 TEQ, some

[[Page 24221]]

sources using wet scrubbing have higher D/F levels. ACI operated at 400 
 deg.F or lower can universally achieve D/F levels of 0.20 ng TEQ/dscm 
or less and is thus the better performing technology. (Note that waste 
heat boilers cannot use rapid quench of combustion gases but can use 
ACI.)
    Although the source equipped with ACI (Waste Technologies 
Industries) is achieving D/F levels of 0.07 ng TEQ/dscm, we believe 
that it is appropriate to conclude that ACI can routinely achieve a 
standard of 0.20 ng TEQ/dscm given the limited application to date of 
the technology for hazardous waste incinerators and the uncertainties 
about how much ACI control efficiency is reduced at extremely low D/F 
emission concentrations. However, we specifically invite comment on the 
potential levels that can be reached with ACI, and on industry-wide 
achievability of 0.07 ng TEQ/dscm as the floor for new sources.
    d. BTF considerations for new sources. At proposal, BTF for new 
sources was based on performance of ACI given that floor control was 
based on performance of rapid quench. Under today's analysis, MACT 
floor for new sources would be based on ACI. Although carbon beds would 
be able to achieve lower emissions, they are not thought to be cost-
effective (particularly if the floor for new sources was well below 
0.20 ng TEQ/dscm), and a BTF standard would likely not be appropriate.
    3. Mercury (Hg). a. MACT floor for existing sources. At proposal, 
the Agency identified floor control as either (1) feedrate control of 
Hg at an maximum theoretical emission concentration (MTEC) not to 
exceed 19 g/dscm, or (2) wet scrubbing with feedrate control 
of Hg at an MTEC not to exceed 51 g/dscm. We proposed a floor 
standard of 130 g/dscm.
    Mercury emissions from incinerators are currently controlled by 
limiting the feedrate of Hg combined with some removal by air pollution 
control systems (APCS). There are two APCS techniques currently used by 
hazardous waste incinerators (HWIs) to control Hg: wet scrubbers and 
ACI. Although primarily intended for acid gas control, nearly all 
incinerators employ wet scrubbers that capture the soluble forms of Hg 
species (e.g., mercury salts). ACI is used by one incinerator for 
control of Hg (and D/Fs). The Agency also has data from one additional 
facility using ACI; however, these data were generated during a 
demonstration testing program.
    Review of the updated Hg data in the revised database shows that 
feedrates vary substantially. Generally the higher feedrates are the 
result of Hg spiking. We re-evaluated the revised database for today's 
notice using a data analysis method similar to that used at proposal to 
determine floor levels: (1) Rank Hg emissions from lowest to highest; 
(2) define as floor control the air pollution control device (APCD) and 
associated highest Hg MTEC for the 6 percent of sources with the lowest 
emissions; and (3) define as the floor standard the highest test 
condition average emissions of any test condition operated at or below 
the Floor MTEC. Using the revised database, MACT control would be 
defined as wet scrubbing with a MTEC of 50 g/dscm, and the 
revised floor standard would be 40 g/dscm. Nearly 60 percent 
of HWIs for which we have data are achieving this level.
    b. BTF considerations for existing sources. The Agency originally 
considered flue gas temperature reduction to 400  deg.F or less 
followed by ACI as the BTF option for improved Hg control. As discussed 
at proposal, EPA believes that ACI incinerator applications can achieve 
Hg emission reductions greater than 90 percent. In the Notice of 
Proposed Rulemaking (NPRM), the Agency proposed a BTF standard of 50 
g/dscm.
    As mentioned above for existing sources, the Agency has in its 
database Hg data from one facility (with two test conditions) currently 
employing ACI as a permanent application. Both test conditions achieved 
Hg removal efficiencies between 97 and 98 percent at varying Hg 
feedrates. The Agency also has data from a second facility generated 
during a demonstration test that show about a 98 percent effectiveness 
at capturing Hg though at one of the highest feedrates in the database. 
These data, in addition to ACI applications on full-scale municipal 
waste combustors and medical waste incinerators,27 support 
the Agency's assumption that ACI systems can readily achieve capture 
efficiencies of 90 percent or more on incinerators.
---------------------------------------------------------------------------

    \27\ USEPA, Section 5 of ``Draft Technical Support Document For 
HWC MACT Standards, Volume III: Selection of Proposed MACT Standards 
and Technologies,'' February 1996.
---------------------------------------------------------------------------

    In light of the revised database, EPA can initially identify 4 
g/dscm as the potential BTF standard based on ACI and flue gas 
temperature reduction to 400  deg.F or less. This is based on a source 
achieving the floor level of 40 g/dscm and then applying ACI 
with a 90 percent removal efficiency. However, a BTF level of 4 
g/dscm will likely raise significant cost-effectiveness 
considerations. Given that the floor level discussed today would be 
substantially lower than the proposed floor, a BTF standard of 4 
g/dscm would be less cost-effective than the BTF levels of 30 
g/dscm and 5 g/dscm analyzed at proposal.
    c. MACT floor for new sources. At proposal, the floor control for 
new sources was similar as for existing sources: wet scrubbing with 
feedrate control of Hg at an MTEC not to exceed 51 g/dscm. We 
proposed a floor standard of 115 g/dscm.
    As discussed for existing sources, both wet scrubbing and ACI are 
used for Hg control. The single best performing source for Hg control 
in our database, measured by lowest emissions, is a wet scrubber with 
Hg feedrate, expressed as a MTEC, of 50 g/dscm. Since MACT for 
new HWIs is identical to MACT for existing sources, analysis of 
emissions using these or better controls would result in a floor level 
for new HWIs of 40 g/dscm.
    The Agency also considered a MACT floor based on ACI, a technology 
more effective at Hg control than typical wet scrubbing applications. 
The three test conditions in the database indicate that ACI was 
effective in removing over 97 percent of Hg. However, the Hg feedrate 
during the single best ACI test condition was higher than the feedrate 
associated with the single best performing wet scrubber. In fact, Hg 
feedrates during the ACI test conditions ranged from 5 to 300 times 
greater than the wet scrubber MTEC level. To determine an emissions 
level that ACI could routinely achieve, we applied a capture efficiency 
of 90 percent to a Hg MTEC of 500 g/dscm, a typical feedrate 
identified by a MTEC breakpoint analysis. Thus, using the revised 
database, the floor level for the ACI evaluation would be 50 
g/dscm which is slightly higher than the wet scrubber floor 
analysis. The floor for new sources based on the wet scrubber 
evaluation appears to be more appropriate because the floor level for 
new sources should be at least as stringent as for existing sources.
    d. BTF considerations for new sources. At proposal, BTF for new 
sources was based on ACI. Similar to existing sources, the Agency re-
considered the use of ACI as the BTF technology. We identified a level 
of 4 g/dscm as a potential BTF standard for new sources based 
on ACI and flue gas temperature reduction to 400  deg.F or less. As 
discussed for existing sources, this BTF level based on ACI will likely 
raise significant cost-effectiveness considerations.
    4. Particulate Matter (PM). a. MACT floor for existing sources. At 
proposal, EPA defined floor control based on either (1) a fabric filter 
with an air-to-

[[Page 24222]]

cloth ratio of 10 acfm/ft2, or (2) a venturi scrubber used 
with an ionizing wet scrubber (IWS). The resulting floor level, which 
included a statistically-derived variability factor, was 0.107 gr/dscf. 
Since this level is higher than the current federal standard of 0.08 
gr/dscf, the Agency identified the floor level as 0.08 gr/dscf.
    Today, in light of the revised database, EPA is taking comment on 
two refined engineering and data analysis methods to identify the PM 
MACT floor for HWIs. The evaluation technique and results from both 
analyses are presented below.
    For the first (and possibly EPA's preferred) data method, EPA would 
use the following steps to identify the PM floor level: (1) Identify 
all PM control equipment currently in use within the HWI source 
category, regardless of measured performance; (2) identify as MACT 
control those PM APCD applications used by at least 6 percent of 
sources that could be expected to routinely and consistently achieve 
superior PM performance relative to all control strategies considered; 
and (3) identify an emissions level that well-designed, operated and 
maintained MACT controls can readily achieve based on generally-
accepted technical and engineering information.
    Using this approach, MACT controls would be fabric filter, IWS, and 
ESP. Based on the revised database, EPA's evaluation of the MACT floor 
performance level readily achievable by a well designed, operated and 
maintained MACT control device (fabric filter, IWS, ESP) is 0.015 gr/
dscf. Note that even though the PM MACT floor is based on fabric 
filter, IWS and ESP APCDs, a source is not required to employ MACT 
floor control but rather only achieve the standard.
    Approximately 75 percent of sources employing MACT (measured by 
available test condition data) currently are achieving 0.015 gr/dscf. 
An evaluation of the remaining PM data exceeding 0.015 gr/dscf from 
sources ostensibly employing MACT indicate that 20 to 40 percent of 
these data may be inappropriate for inclusion (e.g., an incinerator 
with multiple test conditions well below and a few above 0.015 gr/
dscf). Generally, over 50 percent of HWIs, regardless of the PM control 
currently employed, are currently achieving a 0.015 gr/dscf level.
    The second refined data evaluation method EPA is considering for PM 
Floor analysis is similar to the standard-setting process applied at 
proposal. This evaluation is a four-step process: (1) Rank all PM 
emissions data and identify the MACT floor controls used by the best 
performing 6 percent of sources; (2) develop the expanded universe to 
include all sources employing MACT control, without further 
characterizing MACT control (e.g., air-to-cloth ratio of the fabric 
filter, specific collection area for an ESP) as done in the proposal 
because of the absence of reliable detailed design, operating, and 
maintenance information in the database; (3) for each PM test 
condition, evaluate the corresponding SVM system removal efficiency 
(SRE) and screen out sources that have relatively poor SREs (i.e., 
outliers above a breakpoint in the data array), which are indicators of 
poor design, operation, and maintenance characteristics of the MACT 
controls at the source; and (4) identify the MACT floor equal to the 
highest test condition average of all test conditions in the PM 
expanded universe.
    Using this alternative evaluation approach as applied to the 
revised database, MACT would be based on any of the following PM 
controls: (1) Fabric filter, (2) IWS, (3) ESP, or (4) venturi scrubber 
burning liquid low ash wastes. The resultant MACT floor would be 0.029 
gr/dscf. Over 70 percent of HWIs, regardless of the PM control 
equipment employed, are currently achieving this level. A potential 
drawback of using this second alternative evaluation technique is that 
nearly 75 percent of the available incinerator PM data do not have 
corresponding SVM data such that a SRE could be calculated. This 
impacts our ability to identify and screen out poorer performing MACT 
APCDs from the expanded universe, a critical step in evaluating an 
appropriate performance level achievable by MACT control. As a result, 
this evaluation technique may not be appropriately identifying a PM 
floor level representative of MACT. For these reasons, the first data 
method evaluation appears to be more reliable and sound for the 
Agency's revised database. The Agency requests comments on the both 
data analysis methods presented.
    In the NPRM, the Agency proposed that sources maintain continuous 
compliance with the PM standard through the use of a PM CEMS. A 
decision whether to require incinerators to install a PM CEMS will be 
made at the completion of an on-going demonstration testing program to 
determine if at least one PM CEMS can meet the proposed performance 
specifications. Since the floor standards discussed above were based on 
manual test method data, the Agency will re-evaluate at the completion 
of the CEMS testing program whether these PM floor standards would be 
appropriate in the event that the final rulemaking requires continuous 
compliance with a PM CEMS. The Agency will notice the results and 
conclusions of the demonstration test program in the docket for the HWC 
rule.
    b. BTF considerations for existing sources. In the NPRM, the Agency 
proposed a BTF level of 0.030 gr/dscf and solicited comment on an 
alternative BTF level of 0.015 gr/dscf based on improved PM control.
    Based on the revised database, we can evaluate a reduced PM 
emissions level lower than 0.015 gr/dscf as the BTF standard (in 
conjunction with corresponding BTF reductions in SVMs and LVMs) for 
existing HWIs. This would require an improved PM collection technology 
such as the use of more expensive bag material for fabric filters or 
increased plate area or power input to an ESP. Given that the 
alternative floor level analyses presented today would be substantially 
lower than the proposed floor and BTF levels, significant cost-
effectiveness considerations come into play and suggest that a BTF 
standard may not ultimately prove to be appropriate.
    c. MACT floor for new sources. At proposal, the Agency defined 
floor control as a fabric filter with an air-to-cloth ratio of less 
than 3.8 acfm/ft2. The proposed floor level was 0.039 gr/
dscf.
    Based upon our evaluation of the revised database, the floor 
control and emission level discussed above for existing sources would 
also appear to be appropriate for new sources. If this eventuates, then 
MACT floor control would be a well-designed and properly operated PM 
control device (e.g., fabric filter, IWS, or ESP), and the MACT floor 
for new HWIs would be around 0.015 gr/dscf.
    d. BTF considerations for new sources. At proposal, EPA proposed 
the same BTF standard of 0.030 gr/dscf (based on improved PM control) 
as that proposed for existing sources.
    Today, given the cost-effectiveness considerations discussed above 
for existing sources, the Agency is inclined to think that a BTF 
standard beyond a PM floor level of 0.015 gr/dscf (and corresponding 
BTF reductions for SVMs and LVMs) would not ultimately prove to be 
acceptable.
    5. Semivolatile metals (SVM) (cadmium and lead) a. MACT floor for 
existing sources. At proposal, EPA defined floor control as either (1) 
a venturi scrubber with a MTEC not to exceed 170 g/dscm, (2) a 
combination of an ESP and wet scrubber with a MTEC not to exceed 5,800 
g/dscm, or (3) a combination of venturi scrubber and IWS with 
a MTEC less than 49,000

[[Page 24223]]

g/dscm. The proposed floor level was 270 g/dscm.
    HWIs use a combination of good PM control and limiting hazardous 
waste feedrates to control SVM emissions. SVMs, which typically 
vaporize at combustion chamber temperatures and recondense onto small-
size particulates in the APCD, are controlled most efficiently by 
technologies that are effective at capturing fine PM. EPA's revised 
database shows that SVM emissions vary substantially from 2 to nearly 
30,000 g/dscm.
    The refined data analysis method used by EPA to evaluate and 
identify a MACT floor would be based directly on the results from the 
PM floor analyses discussed above. As mentioned there, a floor of 0.015 
gr/dscf would appear to represent the MACT floor for HWIs based on good 
PM control. Since SVMs are controlled, in part, by a well-designed and 
operated PM control devices, it follows that sources achieving this PM 
performance level at typical SVM feedrates should also be controlling 
SVMs emissions.
    Therefore, in its refined SVM analyses of the revised database, the 
Agency first considers all SVM data when corresponding PM measurements 
are below 0.015 gr/dscf. To identify the SVM floor from these data, we 
would determine either the highest SVM test condition average or the 
level that excludes sources achieving substantially poorer SVM control 
than the majority of sources. It is most likely appropriate to use the 
latter approach--excluding sources with significantly poorer SVM 
performance--because their higher SVM emissions may be the result of 
exceedingly high SVM feedrates or some other factor that cannot be 
readily identified with available information (e.g., sampling or 
analysis anomalies). An SVM emissions breakpoint analysis is the 
approach for excluding these poorer performing test conditions.
    Applying this evaluation technique to the revised HWI SVM database 
results in a MACT floor of 100 g/dscm. Approximately 53 
percent of all HWI SVM test condition data, regardless of PM emissions 
level, are currently achieving this emissions level.
    As discussed above for PM, the Agency is soliciting comment on an 
alternative evaluation of the HWI PM data which identified a floor of 
0.029 gr/dscf. Conducting the same SVM floor analysis discussed above 
when PM measurements were below 0.029 gr/dscf also results in the same 
floor of 240 g/dscm. Approximately 60 percent of all HWI SVM 
test condition data, regardless of PM emissions level, are currently 
achieving this emissions level.
    Finally, as discussed in an earlier section, a preliminary analysis 
indicates that MACT standards may not be warranted for one HAP metal, 
antimony. Since the number of metals being considered for MACT 
standards may change, we are investigating the appropriate structure of 
metals standards (e.g., retain the volatility groups or establish 
individual metals standards). Using the refined method discussed above 
for SVM, we analyzed the revised database with respect to Cd and Pb 
data. The floor analysis corresponding to PM measurements below 0.015 
gr/dscf would result in the following floor levels: Cd 20 g/
dscm, and Pb 95 g/dscm. The alternative data analysis method 
for individual metals when corresponding PM measurements were below 
0.029 gr/dscf would result in the following floor levels: Cd 57 
g/dscm, and Pb 95 g/dscm.
    b. BTF considerations for existing sources. In the NPRM, the Agency 
considered a BTF standard for SVMs based on improved PM control below 
0.030 gr/dscf. However, the Agency concluded that a BTF standard would 
not be cost-effective given that the floor level alone would result in 
an estimated 94 percent SVM reduction in emissions.
    As discussed for PM BTF considerations, we also re-evaluated the 
possible appropriateness of using a reduced PM emissions level based on 
improved PM control as a BTF standard (taking into consideration 
corresponding BTF reductions in SVMs) for existing HWIs. Given that the 
alternative PM floor level analyses presented today would be lower than 
the proposed floor and BTF floor levels, significant cost-effectiveness 
considerations emerge and suggest that a BTF standard for either SVMs 
or individual Pb or Cd standards based on improved PM control may not 
ultimately prove to be cost-effective.
    If, however, the revised risk assessment yet to be conducted would 
show significant risk at a SVM floor standard of either 100 g/
dscm or 240 g/dscm, which are floor levels from the two data 
analysis methods discussed above, the Agency will determine whether a 
BTF standard based on control of SVM feedrate to levels below those at 
the floor would be appropriate. This feedrate limitation would in turn 
reduce SVM emissions. The BTF standard and the corresponding level of 
feedrate control would be dictated by considerations of cost-
effectiveness and the need to establish more stringent RCRA-related 
controls.
    c. MACT floor for new sources. At proposal, the Agency defined 
floor control, based on the best performing source, as a combination of 
venturi scrubber and IWS with a MTEC less than 49,000 g/dscm. 
The proposed floor level for new HWIs was 240 g/dscm.
    Based upon our re-evaluation of the database, the floor control and 
emission level discussed above for existing sources for PM and SVMs 
would also appear to be appropriate for new sources. In this event, 
MACT floor control would be a well-designed, operated and maintained PM 
control device (e.g., fabric filter, IWS, or ESP) achieving the PM 
floor level of 0.015 gr/dscf, and the MACT floor would be around 100 
g/dscm.
    As discussed above, the Agency is soliciting comment on an 
alternative evaluation of the revised SVM database which concludes that 
MACT floor control is a well designed, operated and maintained PM 
control device (i.e., fabric filter, IWS, or ESP) achieving a PM level 
of 0.029 gr/dscf. The floor analysis considering all revised SVM data 
when corresponding PM measurements are below 0.029 gr/dscf results in a 
floor for new sources of 240 g/dscm.
    Finally, we have evaluated what individual metal floor levels for 
new sources would be. When PM measurements are below 0.015 gr/dscf, the 
analysis would result in floor levels for Cd of 20 g/dscm and 
for Pb 95 g/dscm. Under the alternative data analysis method 
for individual metals when PM measurements were below 0.029 gr/dscf, 
floor levels would be 57 g/dscm for Cd and 95 g/dscm 
for Pb.
    d. BTF considerations for new sources. In the NPRM, the Agency 
proposed a BTF level of 62 g/dscm based on improved PM control 
below 0.030 gr/dscf.
    As discussed for PM, a reduced PM emissions level based on improved 
PM control could be considered in evaluating a potential BTF standard 
(considering corresponding BTF reductions in SVMs and LVMs) for new 
HWIs. Because the PM floor level presented today would be substantially 
lower than the proposed floor and proposed BTF floor level, cost-
effectiveness issues are again raised and suggest that a BTF standard 
for either SVMs or individual Pb or Cd standards based on improved PM 
control may likewise ultimately prove to be inappropriate.
    6. Low volatile metals (LVM) (arsenic, beryllium, and chromium). a. 
MACT Floor for Existing Sources. At proposal, EPA defined floor control 
as either (1) a venturi scrubber with a MTEC not to exceed 1,000 
g/dscm, or (2) an IWS with a MTEC less than 6,200 g/
dscm.

[[Page 24224]]

The proposed floor level was 210 g/dscm, which included 
antimony.
    HWIs use a combination of good PM control and limiting hazardous 
waste feedrates to control LVM emissions. LVMs are less likely to 
vaporize at combustion temperatures and therefore partition primarily 
to the residue or adsorb onto particles in the combustion gas. EPA's 
database shows that LVM emissions from HWIs vary widely from 1 to over 
130,000 g/dscm.
    To identify a LVM MACT floor, the Agency used the same data 
analysis method applied to the revised SVM database. As was determined 
in the PM analysis of the revised database, a floor of 0.015 gr/dscf 
represents MACT for HWIs based on good PM control. Considering all LVM 
data from sources achieving a PM level 0.015 gr/dscf or better, the 
Agency's evaluation of the revised HWI data results in a LVM floor of 
55 g/dscm (excluding sources above a breakpoint and therefore 
achieving substantially poorer LVM emissions than the majority of 
sources). Over 70 percent of HWI LVM test condition data are currently 
achieving this emissions level.
    As discussed earlier, the Agency is soliciting comment on an 
alternative evaluation of the revised HWI PM data which identified a 
floor of 0.029 gr/dscf. Evaluating the revised LVM data using this 
method results in a LVM floor of 190 g/dscm. Approximately 90 
percent of HWI LVM test condition data are currently achieving this 
level.
    Finally, as discussed in an earlier section, a preliminary analysis 
indicates that MACT standards may not be warranted for one HAP, 
antimony. Since the number of metals being considered for MACT 
standards may change, we are investigating the appropriate structure of 
metals standards (e.g., retain the volatility groups or establish 
individual metals standards). Using the refined method discussed above 
for LVM, we analyzed the revised database with respect to As, Be, and 
Cr (hexavalent). The floor analysis corresponding to PM measurements 
below 0.015 gr/dscf results in the following floor levels: As 21 
g/dscm, Be 2 g/dscm, and Cr (hexavalent) 3 
g/dscm. The alternative data analysis method for individual 
metals when corresponding PM measurements were below 0.029 gr/dscf 
results in the following Floor levels: As 21 g/dscm, Be 2 
g/dscm, and Cr (hexavalent) 5.5 g/dscm.
    The Agency is concerned that some of the potential floor standards 
for some individual metals (e.g., Be, Cr (hexavalent)) may be present 
at levels approaching practical quantitation limits (PQLs). PQLs are 
the lowest level of quantification that the Agency believes a competent 
analytical laboratory can be expected to reliably achieve. The Agency 
will investigate whether this issue may need to be addressed in the 
development of any individual metals standards that may be considered 
for the final rulemaking. We invite comment on the issue of PQLs and 
LVM BTF standards.
    b. BTF considerations for existing sources. In the NPRM, the Agency 
considered a BTF standard for LVMs based on improved PM control below 
0.030 gr/dscf. However, the Agency concluded that a BTF standard would 
not be cost-effective given that the floor level alone would result in 
an estimated 91 percent LVM reduction in emissions.
    As discussed for PM, a reduced PM emissions level based on improved 
PM control could be considered in evaluating a potential BTF standard 
(taking into consideration corresponding BTF reductions in LVMs and 
SVMs) for existing HWIs. Because the PM floor level presented today 
would be substantially lower than the proposed floor and BTF floor 
levels, a BTF standard for either LVMs or individual As, Be, and Cr 
(hexavalent) standards based on improved PM control would raise 
significant cost-effectiveness concerns and may not be appropriate.
    If, however, the revised risk assessment yet to be conducted would 
show significant risk at a LVM floor standard of either 55 g/
dscm or 190 g/dscm, which are floor levels from the two data 
analysis methods discussed above, the Agency will determine whether a 
BTF standard based on control of LVM feedrate to levels below those at 
the floor would be appropriate. This feedrate limitation would in turn 
reduce LVM emissions. The BTF standard and the corresponding level of 
feedrate control would be dictated by considerations of cost-
effectiveness and the need to establish more stringent RCRA-related 
controls.
    c. MACT floor for new sources. At proposal, the Agency defined 
floor control, based on the best performing source, as a venturi 
scrubber with a MTEC less than 1,000 g/dscm. The proposed 
floor level for new HWIs was 260 g/dscm.
    Based upon our re-evaluation of the database, the floor control and 
emission level discussed above for existing sources for PM and LVMs 
would also appear to be appropriate for new sources. MACT floor control 
is a well-designed, operated and maintained PM control device (e.g., 
fabric filter, IWS, or ESP) achieving the PM floor level of 0.015 gr/
dscf, and analysis of the revised data results in a LVM MACT floor of 
55 g/dscm.
    As discussed above, the Agency is soliciting comment on an 
alternative evaluation of the revised LVM database which identifies 
MACT floor control as a well-designed, operated and maintained PM 
control device (e.g., fabric filter, IWS, or ESP) achieving a PM level 
of 0.029 gr/dscf. The floor analysis considering all revised LVM data 
when corresponding PM measurements are below 0.029 gr/dscf results in a 
floor for new sources of 190 g/dscm.
    Finally, individual metal floor levels for new sources, when PM 
measurements are below 0.015 gr/dscf, are: As 21 g/dscm, Be 2 
g/dscm, and Cr (hexavalent) 3 g/dscm. Under the 
alternative data analysis method for individual metals when PM 
measurements are below 0.029 gr/dscf, the floor levels are: As 21 
g/dscm, Be 2 g/dscm, and Cr (hexavalent) 5.5 
g/dscm. [Note: The same PQL concerns would be present here as 
well.]
    d. BTF considerations for new sources. In the NPRM, the Agency 
proposed a BTF level of 60 g/dscm based on improved PM control 
below 0.030 gr/dscf.
    As discussed for PM BTF considerations, the Agency considered a 
reduced PM emissions level based on improved PM control as the BTF 
standard (taking into consideration corresponding BTF reductions in 
LVMs and SVMs) for new (and existing) HWIs. Because the alternative PM 
floor level presented today is substantially lower than the proposed 
floor and BTF floor levels, a BTF standard for either LVMs or 
individual As, Be, or Cr (hexavalent) standards based on improved PM 
control may be inappropriate in light of the cost-effectiveness issues 
inherent in this scenario.
    7. Hydrochloric Acid and Chlorine (HCl/Cl2). a. MACT Floor for 
Existing Sources. At proposal, the Agency defined floor control as wet 
scrubbing with a chlorine MTEC (i.e., maximum theoretical emission 
concentration) up to 2.1E7 ``g/dscm and proposed a floor 
standard of 280 ppmv. While evaluating the revised database, we 
investigated another data analysis method whereby floor control would 
be defined as wet scrubbing combined with chlorine feedrate control to 
achieve an emission level of 75 ppmv.28 Under this method,

[[Page 24225]]

emissions data from sources using wet or dry scrubbing were arrayed 
from lowest to highest (without explicit regard to chlorine feedrate) 
and sources achieving substantially poorer HCl/Cl2 control than other 
sources were screened from the analysis. Accordingly, after five of 48 
test conditions were screened from the analysis for anomalously high 
emission rates,29 the floor standard was established as the 
highest remaining test condition average--75 ppmv.30 Nearly 
90 percent of test conditions 31 in the revised database 
have emission levels below 75 ppmv.
---------------------------------------------------------------------------

    \28\ Although a specific feedrate (i.e., MTEC) level is not used 
to define MACT floor, feedrate control is part of floor control to 
achieve the 75 ppmv standard using wet scrubbing (i.e., a source 
would probably not be able to feed chlorine at extremely high rates 
and still achieve the standard using wet scrubbing). Further, as 
discussed below in the text, sources with anomalously high emissions 
were screened from consideration. One reason that a source may have 
anomalously high emissions is that it may be feeding unusually high 
levels of chlorine.
    \29\ The anomalously high emissions could have been caused by: 
(1) Poor design, operation, or maintenance of the scrubber, and thus 
the device would not represent MACT (e.g., a dry scrubber was 
screened from the analysis because dry scrubbers are generally less 
efficient than wet scrubbers); (2) unusually high chlorine 
feedrates; or (3) sampling or analysis anomalies.
    \30\ The floor standard under this alternative analysis method--
75 ppmv--would be substantially lower than the proposed floor 
standard--280 ppmv--even though feedrate control of chlorine would 
not be used explicitly to help define floor control under this 
alternative method because, to identify the proposed standard, the 
Agency: (1) Selected as the standard-setting test condition the 
highest test condition for sources appearing to be using floor 
control without screening anomalous test conditions; and (2) added a 
computed emissions variability factor to emissions from that 
standard-setting test condition.
    \31\ Considering approximately 50 test conditions where 
emissions levels on both HCl and Cl2 were available.
---------------------------------------------------------------------------

    The Agency requests comment on whether this alternative approach to 
define floor control and a floor level would be more appropriate than 
the proposed approach.
    b. BTF considerations for existing sources. At proposal, the Agency 
determined that a BTF standard would not be warranted. Specifically, 
the Agency noted that risk from emissions at the floor standard would 
not likely trigger the need for additional control under RCRA.
    Although that may prove to be the case as well for the alternative 
standard discussed in today's notice (i.e., 75 ppmv), the risk 
assessment accompanying the final rule will consider incinerators with 
short stacks and will also consider acute risk from HCl and Cl2 during 
short-term exposures. The risk assessment at proposal modeled emissions 
only from incinerators with relatively tall stacks, and did not 
consider acute exposure to HCl and Cl2. If, however, the revised risk 
assessment yet to be conducted shows significant risk at a floor 
standard of 75 ppmv, the Agency will determine whether a BTF standard 
would be appropriate considering cost-effectiveness of such a standard 
and the need to establish more stringent controls under RCRA. In that 
case, BTF control could be based on a minimum system removal efficiency 
(e.g., 99.9 percent) and/or control of chlorine feedrate.
    c. MACT floor for new sources. At proposal, the Agency identified 
floor control for new incinerators as wet scrubbing with an MTEC of 
1.7E7 g/dcsm See 61 FR at 17388. Although the floor control 
for new sources was based on the single best performing source and was 
more stringent than floor control for existing sources, the floor 
emission level was the same for new and existing sources: 280 ppmv.
    When evaluating the revised emissions database considering various 
data analyses methods for today's notice, we determined that floor 
control for new sources should be the same as for existing sources: Wet 
scrubbing with chlorine feedrate control to achieve an emission level 
of 75 ppmv. This is state-of-the-art control for these HAPs. 
Accordingly, the floor standard for new sources would be 75 ppmv under 
this data analysis method.
    d. BTF considerations for new sources. The Agency proposed BTF 
control for new incinerators as 99 percent SRE and a BTF standard of 67 
ppmv. This standard was based on applying 99 percent reduction to the 
test condition in the database with the highest average emission 
without an emission control device (i.e., 1100 ppmv). Then, considering 
other factors including a computed emissions variability factor, the 
Agency determined that a BTF standard of 67 ppmv would be appropriate.
    In retrospect, as we discussed above, virtually all sources are 
already equipped with some form of scrubber and 90 percent are 
achieving emission levels of 75 ppmv or below. Thus, this would be an 
appropriate floor control and standard for new sources. As discussed 
above for existing sources, a BTF standard appears to be unnecessary, 
unless the upcoming final risk analysis indicates that more stringent 
controls under RCRA would be warranted. A BTF standard could be based 
on a minimum system removal efficiency (e.g., 99.9 percent) and/or 
control of chlorine feedrate.
    8. Carbon Monoxide (CO). As proposed, the Agency continues to 
believe that floor control for CO (as a surrogate for organic HAPs) for 
both existing and new sources would be operation under good combustion 
practices. The preponderance of the revised emissions data indicate 
that a floor standard of 100 ppmv over an hourly rolling average (HRA) 
would be readily achievable. In addition, the Agency continues to 
believe that a BTF standard for CO based on better good combustion 
practices is likely to raise significant cost-effectiveness 
considerations.
    9. Hydrocarbons (HC). The Agency proposed that floor control for HC 
(as a surrogate for otherwise unaddressed organic HAPs) for both 
existing and new sources would be operated under good combustion 
practices and that a floor standard of 12 ppmv over an hourly rolling 
average (HRA), would be appropriate. In evaluating the revised emission 
database for today's notice, we used the same general approach for HC 
as at proposal--the entire database was arrayed from the lowest to the 
highest emission levels and assumed that test conditions beyond a 
breakpoint were not operated under good combustion practices. Based on 
that analysis, a floor level for HC of 10 ppmv, HRA, results. (This 10 
ppmv standard does not include a variability factor for reasons 
discussed above, unlike the proposed standard of 12 ppmv that did.) Not 
only does the revised database show that the preponderance of the data 
are below 10 ppmv, but engineering experience and other engineering 
information suggests that a HC level of 10 ppmv is readily achievable 
using good combustion practices.
    As discussed at proposal, the Agency continues to be concerned 
about cost-effectiveness considerations related to BTF controls for HC 
based on operating under better combustion practices.
F. Re-Evaluation of Proposed MACT Standards for Cement Kilns
    We discuss in this section the basis for the revised standards for 
cement kilns that result from applying engineering and data analysis to 
the revised emissions database.32 A comparison of the 
proposed and potentially revised standards for existing and new sources 
is presented in the table below:
---------------------------------------------------------------------------

    \32\ Additional details of the engineering and data analysis 
evaluations performed on the revised emissions database can be found 
in the Agency's background document: USEPA, ``Draft Technical 
Support Document for HWC MACT Standards (NODA), Volume I: MACT 
Evaluations Based on Revised Database'', April 1997.

[[Page 24226]]



                        Table II.F.--Revised Standards for Existing and New Cement Kilns                        
----------------------------------------------------------------------------------------------------------------
                                                               Existing sources               New sources       
                                                         -------------------------------------------------------
                  HAP or HAP Surrogate                      Proposed       Revised      Proposed       Revised  
                                                            standard      standard      standard      standard  
----------------------------------------------------------------------------------------------------------------
D/F (ng TEQ/dscm).......................................     \1\ 0.20          0.20          0.20          0.20 
Hg (g/dscm)....................................        50            72            50            72    
PM (gr/dscf)............................................         0.030         0.030         0.030         0.030
HCl/Cl2 (ppmv)..........................................       630           120            67           120    
CO (ppmv)...............................................       100           100           100           100    
HC (ppmv):                                                                                                      
    Main Stack \2\......................................        20            20            20            20    
    By-Pass.............................................         6.7          10             6.7          10    
SVM (g/dscm)...................................        57           670            55           670    
LVM (g/dscm)...................................       130            63            44           63     
----------------------------------------------------------------------------------------------------------------
\1\ All emission levels are corrected to 7% O2.                                                                 
\2\ Not applicable to preheater and/or precalciner kilns.                                                       

    1. Subcategorization considerations. After analyzing comments 
submitted by the Cement Kiln Recycling Coalition (CKRC) on the proposed 
rule, including information on the types of cement kilns that are 
currently burning hazardous waste, we considered whether the following 
subcategories would be appropriate: (1) Short kilns with separate by-
pass and main stacks; (2) short kilns with a single stack that handles 
both by-pass and preheater or precalciner emissions; (3) long dry kilns 
that use kiln gas to dry raw meal in the raw mill; and (4) others 
(i.e., wet kilns, and long dry kilns not using raw mill drying). Each 
of the first three categories is comprised of only one cement kiln 
facility while the kilns at the remaining 19 facilities are in the 
fourth category: wet kilns or long dry kilns that do not use raw mill 
drying. We find that these subcategories should be considered because 
the unique design or operating features of these kilns could have a 
significant impact on emissions of one or more HAPs that the Agency 
proposed to regulate.
    To determine whether special standards would be appropriate for any 
of the three unique cement kiln types, we identified floor control and 
emission levels considering data only for the other kilns (i.e., wet 
kilns, and long dry kilns not using raw mill drying). We then 
considered whether the unique kiln types could apply the those MACT 
controls and achieve those emission standards. It appears that these 
unique kilns can employ the MACT controls and achieve the corresponding 
emission levels identified in today's notice for the other kilns (i.e., 
wet kilns, and long dry kilns not using raw mill drying). Thus, 
subcategorization would not appear to be needed to determine achievable 
MACT floors for all cement kilns burning hazardous waste.
    2. Dioxins and Furans (D/F). a. MACT Floor for Existing Sources. At 
proposal, the Agency identified floor control as ``temperature control 
at the inlet to the ESP or fabric filter at 418  deg.F''. The proposed 
floor emission level was ``0.20 ng TEQ/dscm, or temperature at the 
inlet to the ESP or fabric filter not to exceed 418  deg.F''.
    Upon re-evaluation of the revised database, we have identified an 
alternative data analysis method that seems more appropriate to 
identify floor control and the floor emission level. Based on an 
engineering evaluation of these data and other available information, 
floor control would be ``temperature control at the inlet to the ESP or 
fabric filter at 400  deg.F''. This results in a floor emission level 
of ``0.20 ng TEQ/dscm, or 0.40 ng TEQ/dscm and temperature at the inlet 
to the ESP or fabric filter not to exceed 400  deg.F''.33
---------------------------------------------------------------------------

    \33\ The standard would be expressed in the form of a TEQ level 
combined with a maximum temperature at the PM control device. This 
form of the standard is consistent with the revised data and would 
result in somewhat lower emissions (i.e., because without the TEQ 
limit, some sources could exceed that TEQ level at the specified 
temperature). Thus, expressing the standard in this form better 
achieves the statutory mandate to establish standards that provide 
the maximum degree of reduction that is achievable in practice.
---------------------------------------------------------------------------

    Temperature control to 400  deg.F or lower is appropriate for floor 
control because, from an engineering perspective, it is within the 
range of reasonable values that could have been selected considering 
that: (1) The optimum temperature window for surface-catalyzed D/F 
formation is 450-750  deg.F; and (2) below 350  deg.F, kiln gas can 
fall below the dew point which can increase corrosion in ESPs and 
fabric filters and reduce performance of the control devices. In 
addition, approximately 20 percent of the test conditions in our 
revised database reflect operations at temperatures of 400  deg.F or 
below. Thus, this temperature level is readily achievable.
    To identify an emission level that temperature control 
400  deg.F could achieve, it is appropriate to pool the 
available emissions data for hazardous waste burning kilns with data 
from nonwaste burning kilns.34 This is because we are not 
aware of an engineering reason why hazardous waste burning would affect 
emissions of D/F. In fact, when the data sets are evaluated separately, 
the highest emitting HW cement kiln operating the ESP or fabric filter 
at temperatures 400  deg.F had D/F emissions of 0.28 ng TEQ/
dscm. The highest emitting nonwaste cement kiln operating at those 
temperatures had D/F emissions of 0.37 ng TEQ/dscm. We believe that the 
difference in emission levels is simply a reflection of many design, 
operation, and maintenance factors on which we have little or no 
information, but which could affect D/F emission levels. An appropriate 
emission level associated with that operating temperature for all 
cement kilns would be 0.40 ng TEQ/dscm. Thus, the floor standard would 
be: ``0.20 ng TEQ/dscm, or 0.40 ng TEQ/dscm and temperature at the 
inlet to the ESP or fabric filter not to exceed 400  deg.F''.
---------------------------------------------------------------------------

    \34\ We considered whether nonwaste cement kiln emission data 
should be pooled with HW cement kiln data for other HAPs and 
determined that emissions of other HAPs, except for PM, could be 
affected by hazardous waste burning. For example, hazardous waste 
can have higher levels of chlorine and metals such as Pb. With 
respect to PM, although it appears appropriate to pool the data 
sets, the better-suited data analysis method is based on the New 
Source Performance Standard, not an analysis of the emissions 
database. Thus, pooling of data would not affect the standard 
derived from that data analysis method. See discussion on the PM 
standard in the text.
---------------------------------------------------------------------------

    b. BTF considerations for existing sources. The Agency proposed a 
BTF standard of 0.20 ng TEQ/dscm based on ACI operated at a temperature 
of 400

[[Page 24227]]

 deg.F. We continue to believe that this BTF standard is appropriate 
given the concerns the Agency has expressed about the risks posed by D/
F emissions, and the Hg reductions that ACI would also provide. See 61 
FR at 17392. Only sources emitting between 0.20 and 0.40 ng TEQ/dscm 
with temperature control alone would need to take further measures to 
reduce D/F levels to 0.20 ng under the BTF standard. Although these 
sources could achieve D/F emission levels well below 0.20 ng TEQ/dscm 
using ACI (i.e., ACI removal efficiency should be in the 95-99 percent 
range), a 0.20 ng TEQ/dscm appears still to be appropriate because it 
may allow some sources to meet the standard more cost-effectively by 
lowering gas temperatures at the ESP or fabric filter below 400  deg.F. 
Further, a BTF standard of 0.20 ng TEQ/dscm would likely avoid the need 
to provide further controls under RCRA authority.
    c. MACT floor for new sources. At proposal, the Agency identified 
floor control for new sources as ``temperature control at the inlet to 
the ESP or fabric filter at 409  deg.F''. The proposed floor emission 
level was ``0.20 ng TEQ/dscm, or temperature at the inlet to the ESP or 
fabric filter not to exceed 409  deg.F''.
    Upon evaluation of the revised database, the floor control and 
emission level discussed above for existing sources would also be 
appropriate for new sources (i.e., ``temperature control at the inlet 
to the ESP or fabric filter at 400  deg.F'' corresponding to an 
emission level of ``0.20 ng TEQ/dscm, or 0.40 ng TEQ/dscm and 
temperature at the inlet to the ESP or fabric filter not to exceed 400 
deg.F''. This is because our engineering evaluation of available 
information and facility operating experience indicates that the best 
controlled source is one that is controlling temperature control at the 
inlet to the fabric filter at 400  deg.F.
    d. BTF considerations for new sources. The Agency proposed ACI as 
BTF control and a BTF standard of 0.20 ng TEQ/dscm. We continue to 
believe that this BTF standard is appropriate for new sources for the 
same reasons discussed above in the context of existing sources.
    3. Mercury (Hg). a. MACT floor for existing sources. At proposal, 
the Agency identified floor control as hazardous waste feedrate control 
not to exceed an MTEC of 110 g/dscm. EPA proposed a floor 
standard of 130 g/dscm.
    All cement kilns employ either ESPs and fabric filters for PM 
control. However, since Hg is generally in the vapor form in and 
downstream of the combustion chamber, including the air pollution 
control device, ESPs and fabric filters do not achieve good mercury 
control. Mercury emissions from cement kilns are currently controlled 
by the BIF rule which establishes limits on the maximum feedrate of Hg 
in total feedstreams (e.g., hazardous waste, raw materials, coal). 
Thus, MACT is based on hazardous waste feed control.
    Review of the revised database indicate that cement kilns only 
infrequently conducted Hg spiking of the hazardous wastes (contrary to 
the Agency's initial information), and thus the Hg content in the 
wastes during testing is likely representative of the Hg content during 
typical operations. The revised data also show that raw materials can 
represent a significant source Hg input to the kiln system. Since 
cement kilns do not employ a dedicated device capable of Hg control, 
the Agency believes that the Hg data are essentially ``normal'' even 
though generated during worst case compliance testing conditions for 
other parameters.
    To evaluate these revised data for the purpose of determining a 
MACT floor, the Agency used the following data analysis steps: (1) Rank 
Hg emissions from lowest to highest; (2) conduct a breakpoint analysis 
on the ranked Hg emissions data, and (3) establish the floor standard 
as the test condition average of the breakpoint source. The breakpoint 
analysis reflects an engineering-based evaluation of the data and 
ensures that the few cement kilns spiking extra Hg do not drive the 
floor level to levels higher than the preponderance of this ``normal'' 
data indicates is routinely achievable. The Agency's analysis results 
in a MACT floor level of 72 g/dscm. The revised database 
indicates that approximately 80 percent of cement kilns are achieving 
this floor level.
    b. BTF considerations for existing sources. The Agency proposed a 
BTF standard of 50 g/dscm based on flue gas temperature 
reduction to 400  deg.F or less followed by ACI. EPA continues to 
believe that ACI is an appropriate BTF technology for cement kilns. 
Although ACI is not employed for Hg control at any full-scale HW cement 
kiln, the Agency is not aware of any cement kiln flue gas conditions 
that would preclude the applicability of ACI--which has been 
demonstrated for other similar types of combustion applications. As 
discussed in the NPRM, EPA assumes that cement kilns employing ACI to 
meet a BTF standard would install the ACI system after the existing ESP 
or fabric filter, and then add on a new fabric filter to remove the 
injected carbon with the adsorbed Hg. Although adding a new fabric 
filter in series is an expensive approach, it will enable cement kilns 
to continue current cement kiln dust (CKD) recycling practices by 
avoiding potential internal build-up of Hg from CKD recycling.
    In the NPRM, the cement kiln BTF standard was based on the 
assumption that an ACI system could routinely achieve Hg emissions 
reductions of 80 to 90 percent. The Agency received public comments 
from, among others, the cement manufacturing industry questioning 
whether a ACI application on a cement kiln could routinely achieve 
capture efficiencies as proposed. The commenters went on to say that 
removal efficiencies of approximately 60 percent were perhaps more 
realistic. We will address these comments specifically as part in the 
final rulemaking, but for the purposes of today's analysis, EPA has 
assumed an ACI effectiveness of 60 percent in identifying BTF levels 
for cement kilns. Thus, the BTF standard for cement kilns would be 30 
g/dscm based on an ACI efficiency of 60 percent applied to the 
potential floor level of 72 g/dscm.
    Ultimately adopting a BTF standard of 30 g/dscm for cement 
kilns will likely involve close scrutiny of cost-effectiveness and 
other factors, including the costs of retrofits that sources will need 
to undertake (e.g., installing the ACI system, add-on of a new fabric 
filter, managing the captured carbon) relative to the emissions 
reductions achieved. Without pre-judging this issue, the Agency's 
experience to date suggests that the final analysis may well reveal 
significant drawbacks associated with the BTF level.
    c. MACT floor for new sources. At proposal, the Agency identified 
floor control for new sources as hazardous waste feedrate control not 
to exceed an MTEC of 28 g/dscm. EPA proposed a floor standard 
of 82 g/dscm.
    The Agency believes that the floor control and emission level 
discussed above for existing sources would also be appropriate for new 
sources. Thus, the MACT floor for new cement kilns would be 72 
g/dscm based on the revised database.
    d. BTF considerations for new sources. At proposal, BTF for new 
sources was based on ACI and we proposed a BTF standard of 50 
g/dscm.
    As discussed for existing sources, the Agency is considering the 
use of ACI and flue gas temperature reduction to 400  deg.F as the BTF 
technology. In evaluating the revised database, EPA has identified a 
level of 30 g/dscm as the BTF standard for new sources based 
on ACI. This is based on a source achieving the MACT new floor level of

[[Page 24228]]

72 g/dscm and then applying ACI with a 60 percent removal 
efficiency. For the same reasons identified for existing sources, the 
Agency is concerned about whether this BTF level based on ACI will 
ultimately prove to be cost-effective for new cement kiln sources.
    4. Particulate Matter (PM). a. MACT floor for existing sources. At 
proposal, EPA defined floor control as a fabric filter with an air-to-
cloth ratio of 2.3 acfm/ft2. The floor analysis led to a 
level of 0.065 gr/dscf, but due to concerns with the appropriateness of 
using a statistically-derived variability factor, the Agency instead 
established the floor standard based on the cement kiln New Source 
Performance Standard (NSPS). The NSPS is a process emissions rate that 
converts to an approximate flue gas concentration of 0.03 gr/dscf.
    Today, EPA is taking comment on two data analysis methods to 
identify the PM floor standard for cement kilns. The first data 
analysis method would be to establish the floor standard equivalent to 
the NSPS, which is 0.3 lbs PM per ton of dry raw material feed. 
Currently, approximately 20 percent of HW cement kilns are subject to 
the NSPS. Cement kilns achieve the NSPS with well-designed and properly 
operated ESPs or fabric filters.
    A second data analysis method considered and potentially preferred 
would be to express the NSPS as a stack gas concentration limit as done 
in the NPRM. The conversion of the NSPS to a concentration standard 
will vary by kiln process type (e.g., wet, dry, preheater, preheater/
precalciner) because the amount of flue gas generated per ton of raw 
material feed varies by process type. Based on typical factors of flue 
gas quantities generated per ton of raw material feed and flue gas 
moisture content, the NSPS equates to a PM concentration of 
approximately 0.03 gr/dscf for wet process kilns (also the least energy 
efficient) and 0.05 gr/dscf for preheater kilns (the most energy 
efficient). The total HW cement kiln universe is comprised of 41 kilns 
with varying process types: 27 wet, 12 long dry, one preheater/
precalciner, and one preheater. Of the cement kilns currently subject 
to the NSPS standard, four are wet, two are long dry, one preheater/
precalciner, and one preheater.
    Notwithstanding that the concentration equivalent of the NSPS can 
vary by process type, establishing the floor standard for all cement 
kilns at 0.030 gr/dscf appears to be appropriate regardless of 
manufacturing process utilized, for the following reasons: (1) The 
majority (66 percent) of the cement kilns are wet process kilns for 
which the NSPS concentration equivalent is 0.030 gr/dscf. For these 
kilns, this floor method would not differ from the initial NSPS method 
used in the proposal. (2) Our database shows non-wet process kilns have 
at least one test condition (in addition to three quarters of all non-
wet process kiln data) achieving 0.030 gr/dscf. Therefore, 
achievability of the floor appears to be satisfied. (3) Even though wet 
process kilns typically have lower inlet grain loadings than the non-
wet processes, non-wet kilns are achieving the 0.030 gr/dscf level. 
Again, the achievability requirement is met. Thus, the Agency believes 
that it is appropriate to establish the MACT floor for existing sources 
at 0.030 gr/dscf.
    In the NPRM, the Agency proposed that sources maintain continuous 
compliance with the PM standard through the use of a PM CEMS. A 
decision whether to require cement kilns to install a PM CEMS will be 
made at the completion of an on-going demonstration testing program to 
determine if at least one PM CEMS can meet the proposed performance 
specifications. Since the floor standards discussed above were based on 
manual test method data, the Agency will re-evaluate at the completion 
of the CEMS testing program whether these PM floor standards would be 
appropriate in the event that the final rulemaking requires continuous 
compliance with a PM CEMS. The Agency will make available the results 
and conclusions of the demonstration test program in the docket for the 
HWC rule.
    b. BTF considerations for existing sources. In the NPRM, the Agency 
considered a BTF level of 0.015 gr/dscf based on improved PM control. 
However, we determined that such a standard would not likely be cost-
effective. We did not have adequate data to ensure that, given the high 
inlet grain loading caused by entrained raw material, cement kilns 
could routinely achieve 0.015 gr/dscf and below with a single fabric 
filter or ESP.
    In light of the revised database, the Agency again considered a BTF 
PM emissions level based on improved PM control. Because the floor 
level of 0.030 gr/dscf presented today is the same as the proposed 
floor, a BTF standard lower than 0.030 gr/dscf (even with corresponding 
BTF reductions for SVMs and LVMs) appears not to be cost-effective 
based on information developed at proposal.
    c. MACT floor for new sources. At proposal, the Agency defined 
floor control as a fabric filter with an air-to-cloth ratio of less 
than 1.8 acfm/ft2. The floor analysis lead to a level of 
0.065 gr/dscf. Due to concerns with the appropriateness of the 
statistically-derived variability factor, the Agency instead 
established the floor standard based on the cement kiln NSPS. The NSPS 
is a process emissions rate that the Agency converted to an approximate 
flue gas concentration of 0.030 gr/dscf.
    Upon evaluation of the revised database discussed for existing 
sources, EPA continues to believe that the floor standard discussed 
above for existing sources would also be appropriate for new sources. 
Therefore, MACT floor control is a well-designed and properly operated 
PM control device (e.g., fabric filter, ESP), and the MACT floor for 
new cement kilns would be 0.030 gr/dscf.
    d. BTF considerations for new sources. In the NPRM, EPA considered 
a BTF standard based on improved PM control to be consistent with 
existing sources. However, we found that the BTF level would not be 
cost-effective.
    Today, as discussed above for existing source BTF considerations 
and based upon examining the revised database in light of the findings 
at proposal, a BTF standard beyond a PM level of 0.030 gr/dscf (and 
corresponding BTF reductions for SVMs and LVMs) would not appear to be 
cost-effective.
    5. Semivolatile Metals (SVM) (cadmium and lead). a. MACT Floor for 
Existing Sources. At proposal, EPA defined floor control as a fabric 
filter with an air-to-cloth ratio less than 2.1 acfm/ft2 and 
a HW MTEC of 84,000 g/dscm. The proposed floor level was 57 
g/dscm.
    Cement kilns use a combination of good PM control and limiting 
hazardous waste feedrates to control SVM emissions. SVMs are controlled 
most efficiently by technologies, such as fabric filters, which are 
effective at capturing fine PM. EPA's database shows that SVM emissions 
vary substantially from 1 to over 6,000 g/dscm.
    The engineering evaluation and data analysis method used by EPA to 
evaluate and identify a MACT floor from the revised database is an 
extension of the PM floor analyses of the revised database. As 
discussed in the PM analysis, a floor of 0.030 gr/dscf could represent 
MACT based on good PM control. Since SVMs are controlled, in part, by a 
well-designed and operated PM control device, it follows that sources 
achieving this PM performance level should also be controlling SVM 
emissions at typical SVM feedrates. Therefore, in its refined SVM 
analysis of the revised database, EPA would first consider all SVM data 
when corresponding PM measurements are below 0.030 gr/dscf. To identify 
the SVM floor from these data, we would identify the floor at the level 
that

[[Page 24229]]

excludes (by breakpoint analysis) sources achieving substantially 
poorer SVM control than the majority of sources. As noted earlier in 
the case of HWIs, it is appropriate to exclude sources with 
significantly poorer SVM performance because their higher SVM emissions 
may be the result of exceedingly high SVM feedrates or some other 
factor that shows the test condition did not actually reflect MACT 
floor controls. The Agency does not have available information to 
otherwise screen out these non-MACT test conditions from the expanded 
universe for SVM.
    The Agency's evaluation of the revised cement kiln SVMs data 
results in a MACT floor of approximately 670 g/dscm. 
Approximately 85 percent of SVM test condition data are currently 
achieving this emissions level.
    Finally, as discussed in an earlier section, a preliminary analysis 
indicates that MACT standards may not be warranted for one HAP metal, 
antimony. Since the number of metals being considered for MACT 
standards may change, we are investigating the appropriate structure of 
metals standards (e.g., retain the volatility groups or establish 
individual metals standards). Using the refined method discussed above 
for SVM, we analyzed the revised database with respect to Cd and Pb 
data. The floor analysis corresponding to PM measurements below 0.030 
gr/dscf would result in the following floor levels: Cd 60 g/
dscm, and Pb 560 g/dscm.
    b. BTF considerations for existing sources. In the NPRM, the Agency 
considered a BTF standard for SVMs based on improved PM control below 
0.030 gr/dscf. However, the Agency concluded that a BTF standard would 
not be cost-effective given that the SVM Floor level of 57 g/
dscm alone would result in an estimated 94 percent SVM reduction in 
emissions.
    As discussed for PM BTF considerations, the Agency also re-
evaluated the possible appropriateness of using a reduced PM emissions 
level based on improved PM control as a BTF standard (with 
corresponding BTF reductions in SVMs and LVMs). Even though the SVM 
floor standard is higher than at proposal, our preliminary judgment is 
that significant cost-effectiveness considerations will likely be 
encountered in a final analysis of whether to establish a BTF standard 
for either SVMs or for Pb or Cd individually.
    If, however, the revised risk assessment yet to be conducted would 
show significant risk at a SVM floor standard of either 670 g/
dscm, the Agency will determine whether a BTF standard based on control 
of HW SVM feedrate to levels below those at the floor would be 
appropriate. This feedrate limitation would in turn reduce SVM 
emissions. The BTF standard and the corresponding level of feedrate 
control would be dictated by considerations of cost-effectiveness and 
the need to establish more stringent RCRA-related controls.
    c. MACT floor for new sources. At proposal, the Agency defined 
floor control, based on the best performing source, as a fabric filter 
with an air-to-cloth ratio less than 2.1 acfm/ft2 and a HW 
MTEC of 36,000 g/dscm The proposed floor level for new cement 
kilns was 55 g/dscm.
    Upon evaluation of the revised database, EPA believes that the 
floor control and emission level discussed above for existing sources 
for SVMs would also be appropriate for new sources. In this event, MACT 
floor control would be a well-designed, operated and maintained PM 
control device (i.e., fabric filter or ESP) achieving the PM floor 
level of 0.030 gr/dscf. The Agency's evaluation of the revised SVM data 
results in a MACT floor of 670 g/dscm.
    Finally, based on the revised database, individual metal floor 
levels for new sources are identical to those for existing sources. 
Thus, individual Cd and Pb standards are: Cd 65 g/dscm and Pb 
550 g/dscm.
    d. BTF Considerations for new sources. In the NPRM, the Agency 
considered a SVM BTF level, but determined that a BTF standard would 
not be cost-effective.
    As discussed for existing sources, the Agency considered a more 
stringent PM emissions level for improved control of PM, SVM and LVM 
emissions for new cement kilns in light of the revised database. Even 
though the SVM floor standard is higher than at proposal, our 
preliminary judgment is that significant cost-effectiveness 
considerations will likely be encountered in a final analysis of 
whether to establish a BTF standard for either SVMs or for Pb or Cd 
individually.
    6. Low Volatile Metals (LVM) (arsenic, beryllium, and chromium). a. 
MACT floor for existing sources. At proposal, EPA defined floor control 
as either (1) a fabric filter with an air-to-cloth ratio less than 2.3 
acfm/ft 2 and a HW MTEC of 140,000 g/dscm, or (2) 
an ESP with a specific collection area of 350 ft2/kacfm. The 
proposed floor level was 130 g/dscm, which included antimony.
    The engineering and data analysis method used by EPA to evaluate 
the revised database and identify a MACT floor for LVMs is also related 
directly to the PM floor analysis. As was determined in the PM 
analysis, a floor of 0.030 gr/dscf represents MACT for cement kilns 
based on good PM control. Considering all LVM data from sources 
achieving a PM level 0.030 gr/dscf or better, EPA's evaluation of the 
revised cement kiln data would result in a LVM floor of 63 g/
dscm (excluding sources above a breakpoint and therefore excluding 
those with substantially poorer LVM emissions than the majority of 
sources). Approximately 90 percent of cement kiln LVM test condition 
data are currently achieving this emissions level.
    Finally, as discussed for SVMs, EPA is continuing to investigate 
the appropriate structure of metals standards (e.g., retain the 
volatility groups or establish individual metals standards). The Agency 
analyzed individual As, Be, and Cr (hexavalent) data and established 
individual metal floor levels consistent with the engineering 
evaluation and data analysis method. Where PM measurements are below 
0.030 gr/dscf, the result would be: As 10 g/dscm, Be 1.1 
g/dscm, and Cr (hexavalent) 4.6 g/dscm.
    The Agency is concerned that some of the potential floor standards 
for some individual metals (e.g., Be, Cr (hexavalent)) may be present 
at levels approaching practical quantitation limits (PQLs). PQLs are 
the lowest level of quantification that the Agency believes a competent 
analytical laboratory can be expected to reliably achieve. The Agency 
will investigate whether this issue may need to be addressed in the 
development of any individual metals standards that may be considered 
for the final rulemaking. We invite comment on the issue of PQLs and 
LVM BTF standards.
    b. BTF considerations for existing sources. In the NPRM, the Agency 
considered a BTF standard for LVMs based on improved PM control below 
0.030 gr/dscf. However, the Agency concluded that a BTF LVM standard 
would not be cost-effective.
    As discussed for PM, a reduced PM emissions level based on improved 
PM control could be considered in evaluating a potential BTF standard 
(taking into consideration corresponding BTF reductions in LVMs and 
SVMs) for existing CKs. Because both the PM and LVM floor levels 
presented today would be similar to the proposed floor, a BTF standard 
for either LVMs or individual As, Be, and Cr (hexavalent) standards 
based on improved PM control would likely raise

[[Page 24230]]

significant cost-effectiveness concerns and may not ultimately be 
appropriate.
    c. MACT floor for new sources. At proposal, the Agency defined 
floor control, based on the best performing source, as a fabric filter 
with an air-to-cloth ratio less than 2.3 acfm/ft2 and a HW 
MTEC of 25,000 g/dscm. The proposed LVM floor level for new 
CKs was 44 g/dscm.
    Based upon our re-evaluation of the database, the floor control and 
emission level discussed above for existing sources for LVMs would also 
appear to be appropriate for new sources. MACT floor control is a well-
designed and properly operated PM control device (i.e., fabric filter, 
ESP) achieving the PM floor level of 0.030 gr/dscf. The Agency's 
evaluation of the LVM data results in a MACT floor of 63 g/
dscm.
    Finally, individual metal floor levels for new sources are 
identical to those for existing sources. Thus, the standards would be: 
As 10 g/dscm, Be 1.1 g/dscm, and Cr (hexavalent) 4.6 
g/dscm.
    d. BTF considerations for new sources. In the NPRM, the Agency 
considered a LVM BTF level, but determined that a BTF standard would 
not be cost-effective.
    As discussed for existing sources, the Agency considered a more 
stringent PM emissions level for improved control of PM, SVM and LVM 
emissions for new CKs. Because both the alternative PM and LVM floor 
levels presented today are lower than the proposed floors, a BTF 
standard for either LVMs or individual As, Be, or Cr (hexavalent) 
standards based on improved PM control may be inappropriate in light of 
the cost-effectiveness concerns inherent in this scenario.
    7. Hydrochloric Acid and Chlorine (HCl/Cl2). a. MACT 
floor for existing sources. At proposal, the Agency identified floor 
control for total chlorine (i.e., HCl + Cl2) as feedrate 
control of chlorine in the hazardous waste at an MTEC not to exceed 1.6 
g/dscm, and proposed a floor standard of 630 ppmv. When we evaluated 
the revised database prior to today's notice, we used a data analysis 
method similar to that used at proposal. The floor control would be 
defined the same way as proposed, but the floor standard would be 120 
ppmv. This standard should be readily achievable given that 93 percent 
of the test conditions in the revised database are meeting that level.
    We used the following data analysis steps for both the proposed 
standard and today's alternative standard: (1) Rank emissions from 
lowest to highest; (2) define as floor control the highest hazardous 
waste chlorine MTEC for the 6 percent of sources \35\ with the lowest 
emissions; and (3) define as the floor standard the highest test 
condition average emissions of any test condition operated at or below 
the floor MTEC (i.e., the expanded universe). We then refined the data 
analysis method in two respects based on an engineering evaluation of 
the revised database: (1) We did not add a computed emissions 
variability factor \36\; and (2) several test conditions were deleted 
from the expanded universe where an engineering evaluation revealed 
that SREs were significantly worse than the majority of other SREs.
---------------------------------------------------------------------------

    \35\ Or where we had data from fewer than 30 sources, the three 
sources with the lowest emissions (i.e., 3 represents the median of 
the five best performing sources).
    \36\ See previous discussion in the text. As we discussed at 
proposal (61 FR at 17396), the computed variability factor for this 
standard resulted in a standard that did not comport with 
engineering information on the APCDs at issue, engineering 
experience on facility performance within this source category, or 
the emissions database.
---------------------------------------------------------------------------

    In the case of total chlorine emissions for CKs, it appears not to 
be appropriate to use a breakpoint analysis to screen from the expanded 
universe sources that are not achieving an appropriate removal 
efficiency. This is because total chlorine is removed incidentally by 
reactions with the alkaline raw materials (e.g., limestone). Thus, it 
is difficult to reason that poor SRE is caused by poor design, 
operation, or maintenance of the control system. Nonetheless, we 
believe it is still appropriate to screen out clearly anomalous SREs 
because they are likely indicative of an incorrect MTEC value or 
emission measurement. An incorrect value for either could affect the 
floor standard.\37\
---------------------------------------------------------------------------

    \37\ The floor standard without screening the anomalous SREs 
would have been 160 ppmv.
---------------------------------------------------------------------------

    b. BTF considerations for existing sources. At proposal, the Agency 
defined BTF control as wet scrubbing with a 99 percent removal 
efficiency, but determined that a BTF standard would not be cost-
effective. Given that the alternative floor level presented today would 
be substantially lower than the proposed floor, a BTF standard would be 
less cost-effective. Thus, we believe that our final analysis is likely 
to conclude that a BTF standard would not be warranted.
    c. MACT floor for new sources. At proposal, the Agency defined 
floor control for new sources as hazardous waste feedrate control for 
chlorine at an MTEC of 1.6 g/dscm or less. The proposed floor standard 
was 630 ppmv, the same as the floor standard for existing sources.
    Given that the alternative data analysis method discussed above for 
existing sources did not change the expanded universe, except to screen 
out test conditions with anomalous SREs, MACT floor control and the 
floor emission level would be the same as for existing sources: 
hazardous waste feedrate control for chlorine at an MTEC of 1.6 g/dscm 
or less, resulting in a floor standard of 120 ppmv (i.e., after 
screening out test conditions with anomalous SREs).
    d. BTF considerations for new sources. The Agency proposed a BTF 
standard for new sources of 67 ppmv based on wet scrubbing. Given that 
under the revised data analysis method discussed today the floor 
standard would be much lower than proposed, the Agency believes that 
the economic impact analysis being conducted in support of the final 
rule is likely to raise significant concerns about cost-effectiveness. 
In that event, the Agency would promulgate the 120 ppmv floor standard 
for new sources.
    8. Carbon Monoxide (CO). The Agency proposed the same MACT floor 
standards for CO for existing and new CKs, and determined that BTF 
controls would not be cost-effective. Floor control was defined for 
kilns with by-pass ducts as operation under good combustion practices 
and the standard was 100 ppmv, HRA, measured in the by-pass duct. For 
kilns without a by-pass duct (i.e., long wet and dry kilns), no CO 
standard was proposed given that CO levels in the main stack would not 
be an indicator of combustion efficiency. This is because CO can be 
generated by process chemistry (i.e., dissociation of CO2 to 
form CO) and evolution from trace organics in the raw material 
feedstocks, as well as from combustion of fuels.
    The Agency continues to believe that the proposed CO standard for 
kilns equipped with a by-pass duct would be appropriate. However, under 
one option being considered for limiting CO (and HC) emissions, kilns 
without a by-pass duct would also be required to comply with a CO limit 
based on the level achieved during the performance test demonstrating 
compliance with the HC limit. See discussion in Part Two, Section II.C.
    Finally, the Agency continues to believe that a BTF standard for CO 
based on better combustion practices is likely to raise significant 
cost-effectiveness considerations.
    9. Hydrocarbons (HC). The Agency proposed the same MACT floor 
standards for HC for existing and new CKs, and determined that BTF 
controls would not be cost-effective. Floor

[[Page 24231]]

control was defined for kilns with by-pass ducts as operation under 
good combustion practices and the standard was 6.7 ppmv, based on an 
hourly rolling average (HRA and measured in the by-pass duct. For kilns 
without a by-pass duct (i.e., long wet and dry kilns), floor control 
was defined as good combustion practices and use of raw materials with 
relatively low organic content, and the standard was 20 ppmv, HRA, 
measured in the main stack.
    In evaluating the revised database for today's notice, the 20 ppmv 
standard still appears to be appropriate for the main stack of long 
kilns 38. When considering by-pass kilns, however, the 
revised database still lacks HC emissions data for the only two CKs 
currently burning hazardous waste in units equipped with by-pass ducts. 
These two sources are complying with the BIF rules by documenting that 
CO levels are below 100 ppmv, HRA. 39 Under one attractive 
option for compliance with the CO and HC standards (i.e., sources would 
have the option of complying with either the CO or HC standard; see 
discussion in Part Two, Section II.C), we would expect that these two 
sources would continue to comply with the CO limit. Thus, it may not be 
necessary to establish a HC limit for them. However, given that it may 
be prudent to establish a HC limit for these by-pass kilns, we would 
transfer the good combustion practices-based HC standard for 
incinerators--10 ppmv, HRA--to these kilns. This is appropriate 
because: (1) Good combustion practices is floor control for CO and HC 
for these kilns as well as for incinerators; and (2) given that the 
good combustion practices-based CO standard is the same for 
incinerators and by-pass kilns, the good combustion practices-based HC 
standard should also be the same.
---------------------------------------------------------------------------

    \38\  The Agency did not propose a HC standard for the main 
stack of a preheater or preheater/precalciner kiln. See FR at 17397-
8. The Agency is currently developing MACT standards for non-waste 
burning cement kilns, however. Any standards that the Agency may 
propose that are applicable to the main stack of a preheater or 
preheater/precalciner non-waste burning kiln may also be appropriate 
for the main stack of such hazardous waste burning kilns.
    \39\  The two kilns operating with by-pass ducts are Medusa's 
facility in Demopolis, AL, and Lone Star's facility in Cape 
Girardeau, MO. We note that Holnam has a long wet kiln in 
Clarksville, MO that has been retrofitted with a mid-kiln sampling 
port for purposes of monitoring CO in compliance with the BIF rule. 
That monitoring approach would be acceptable under the MACT rule as 
well.
---------------------------------------------------------------------------

    As discussed at proposal, the Agency continues to be concerned 
about cost-effectiveness considerations related to BTF controls for HC 
based on operating under better combustion practices.
G. Re-Evaluation of Proposed MACT Standards for Lightweight Aggregate 
Kilns
    We discuss in this section the basis for the revised standards for 
LWAKs that could result from applying various engineering evaluation 
and data analysis methods to the revised emissions database 
40. A comparison of the proposed and potentially revised 
standards for existing and new sources is presented in the table below:
---------------------------------------------------------------------------

    \40\ Additional details of the engineering and data analysis 
evaluations performed on the revised emissions database can be found 
in the Agency's background document: USEPA, ``Draft Technical 
Support Document for HWC MACT Standards (NODA), Volume I: MACT 
Evaluations Based on Revised Database'', April 1997.

                          Table II.G:--Revised Standards for Existing and New LWAKs \1\                         
----------------------------------------------------------------------------------------------------------------
                                                               Existing sources               New sources       
                                                         -------------------------------------------------------
                  HAP or HAP surrogate                      Proposed       Revised      Proposed       Revised  
                                                            standard      standard      standard      standard  
----------------------------------------------------------------------------------------------------------------
D/F (ng TEQ/dscm).......................................         0.20          0.20          0.20          0.20 
Hg (g/dscm)....................................        72            47            72            47    
PM (gr/dscf)............................................         0.030         0.022         0.030         0.022
HCl/Cl2 (ppmv)..........................................       450           130            62            43    
CO (ppmv)...............................................       100           100           100           100    
HC (ppmv)...............................................        14            10            14            10    
SVM (g/dscm)...................................        12            76             5.2          76    
LVM (g/dscm)...................................       340            37            55           37     
----------------------------------------------------------------------------------------------------------------
\1\ All emission levels are corrected to 7% O2.                                                                 

    1. Dioxins and Furans (D/F). a. MACT floor for existing sources. At 
proposal, the Agency had D/F emissions for only one LWAK and therefore 
pooled that LWAK data point with D/F data for CKs to identify MACT 
standards. Consequently, floor control and the floor emission level for 
LWAKs were the same as for CKs. The proposed floor control was 
``temperature control at the inlet to the fabric filter 41 
at 418  deg.F'', and the proposed floor emission level was ``0.20 ng 
TEQ/dscm, or temperature at the inlet to the fabric filter not to 
exceed 418  deg.F''. The Agency reasoned that pooling D/F data for 
LWAKs and CKs could be appropriate because both types of devices are 
designed and operated similarly with respect to factors that can affect 
surface-catalyzed D/F formation. Both LWAKs and CKs have high PM inlet 
loadings comprised primarily of entrained raw material and both are 
equipped with fabric filters that operate within the same temperature 
range.
---------------------------------------------------------------------------

    \41\ All LWAKs currently burning hazardous waste are equipped 
with fabric filters.
---------------------------------------------------------------------------

    Commenters on the proposed rule, however, argued that pooling LWAK 
and CK D/F data was inappropriate for purposes of establishing MACT 
standards for LWAKs. Since proposal, the Agency has obtained D/F 
emissions data from two additional LWAK facilities. These data are 
included in the revised emissions database and are used to identify the 
alternative standards presented here.
    Based upon evaluation of the revised LWAK D/F database, our 
engineering evaluation of the data and other information on LWAK 
performance suggests the floor control can be specified as 
``temperature control at the inlet to the fabric filter at 400 
deg.F''. This would result in a floor emission level of ``0.20 ng TEQ/
dscm, or 4.1 ng TEQ/dscm and temperature at the inlet to the fabric 
filter not to exceed 400  deg.F'.42 Given that the entire 
revised database also comprises the expanded universe (all sources 
using floor control) the highest single run for the test condition

[[Page 24232]]

with the highest run average would be a reasonable floor level from an 
engineering perspective. (Note that if this were a large data set, the 
floor level could be identified simply as the highest test condition 
average.) This floor level is more than 40 percent higher than the 
highest test condition average (because of substantial variability 
among the runs for that test condition), and thus appears to be a level 
that LWAKs should be able to meet routinely using floor control.
---------------------------------------------------------------------------

    \42\ The standard would be expressed in the form of a TEQ level 
combined with a maximum temperature at the PM control device. This 
form of the standard is consistent with the revised data and would 
result in somewhat lower emissions (i.e., because without the TEQ 
limit, some sources could exceed that TEQ level at the specified 
temperature). Thus, expressing the standard in this form better 
achieves the statutory mandate to establish standards that provide 
the maximum degree of reduction that is achievable in practice.
---------------------------------------------------------------------------

    As discussed for CKs, temperature control to 400  deg.F or less is 
appropriate for floor control because, from an engineering perspective, 
it is within the range of reasonable values that could have been 
selected considering that: (1) The optimum temperature window for 
surface-catalyzed D/F formation is 450-750  deg.F; and (2) below 350 
deg.F, kiln gas can fall below the dew point which can increase 
corrosion in fabric filters and reduce performance of the control 
device. In addition, more than three LWAKs in the revised database were 
operated at temperatures of 400  deg.F or less (even though we do not 
have D/F emissions data for them). Thus, this temperature level appears 
to be readily achievable.
    Although only two of the three LWAKs for which we have D/F 
emissions data operated the fabric filter at 400  deg.F or lower (the 
third operated at 417  deg.F), we have fabric filter operating data for 
other LWAKs when performing emissions testing for other HAPs that 
document fabric filter operations at 400  deg.F or lower. The LWAK 
whose fabric filter was operated at 417  deg.F had lower D/F emissions 
than a kiln whose fabric filter was operated at 400  deg.F. Thus, even 
though our engineering evaluation did not explicitly include the LWAK 
whose fabric filter operated at 417  deg.F, defining MACT floor control 
as ``temperature control at the inlet to the fabric filter at 400 
deg.F'' did not result in a lower MACT floor emission level (i.e., 
lower than 4.1 ng TEQ/dscm). Rather, doing so ensures that LWAKs will 
be operating at floor levels consistent with sound operational 
practices for controlling D/F.
    b. BTF considerations for existing sources. The Agency proposed a 
BTF standard of 0.20 ng TEQ/dscm based on ACI operated at a temperature 
of 400  deg.F.
    Upon evaluation of the revised LWAK D/F database, LWAKs appear to 
be able to achieve a 0.20 ng TEQ/dscm standard simply by rapidly 
quenching combustion gases at the exit of the kiln to 400 
deg.F, and insulating the duct-work leading to the fabric filter to 
maintain gas temperatures and avoid dew point problems. Although the 
data are not conclusive, and further testing is warranted to confirm 
this approach, our engineering evaluation of all available information 
indicates that this approach should be feasible.43 If this 
approach proves to be less effective than anticipated, then ACI can be 
used to achieve the BTF standard.
---------------------------------------------------------------------------

    \43\ See USEPA, ``Draft Technical Support Document for HWC MACT 
Standards (NODA), Volume I: MACT Evaluations Based on Revised 
Database'', April 1997.
---------------------------------------------------------------------------

    We continue to believe that this BTF standard is appropriate given 
the concerns the Agency has expressed about the risks posed by D/F 
emissions. See discussion regarding a D/F BTF standard for CKs at 61 FR 
17392. Further, a BTF standard of 0.20 ng TEQ/dscm would preclude the 
need to provide further controls under RCRA authority.
    c. MACT floor for new sources. At proposal, the BTF considerations 
for new LWAKs were the same as for new CKs, and the proposed standards 
were the same.
    Upon evaluation of the revised LWAK D/F database, the floor control 
and emission level discussed above for existing sources would also 
appear to be appropriate for new sources (i.e., ``temperature control 
at the inlet to the fabric filter at 400  deg.F'' corresponding to an 
emission level of ``0.20 ng TEQ/dscm, or 4.1 ng TEQ/dscm and 
temperature at the inlet to the fabric filter not to exceed 400 
deg.F''. Our engineering evaluation indicates that the best controlled 
source is one that is controlling temperature control at the inlet to 
the fabric filter at 400  deg.F.
    d. BTF considerations for new sources. The Agency proposed ACI as 
BTF control and a BTF standard of 0.20 ng TEQ/dscm. We continue to 
believe that this BTF standard is appropriate for new sources for the 
same reasons discussed above in the context of existing sources. Note 
that BTF control, as for existing sources, would be defined as rapid 
quench of kiln gas to 400  deg.F combined with duct 
insulation, as required, or ACI operated at 400  deg.F.
    2. Mercury (Hg) a. MACT Floor for existing sources. At proposal, 
the Agency identified floor control as hazardous waste feedrate control 
not to exceed an MTEC of 17 g/dscm. EPA proposed a floor 
standard of 72 g/dscm.
    All LWAKs employ fabric filters and one source uses a fabric filter 
and venturi scrubber to control mercury. However, since Hg is generally 
in the vapor form in and downstream of the combustion chamber, 
including the air pollution control device, fabric filters alone do not 
achieve good mercury control. Mercury emissions from LWAKs are 
currently controlled under the BIF rule, which establishes limits on 
the maximum feedrate of Hg in total feedstreams (e.g., hazardous waste, 
raw materials). Thus, MACT is based on hazardous waste feed control.
    Review of the updated Hg data in the revised database indicate that 
LWAKs did not conduct Hg spiking of the hazardous wastes with the 
exception of one facility, and thus the Hg content in the wastes during 
testing is likely representative of typical operations. The data from 
this testing also show that raw materials can represent a significant 
source Hg input to the kiln system. Since the best performing sources, 
measured by Hg emissions, do not employ a dedicated device capable of 
Hg control, the Agency believes that the Hg data are essentially 
``normal'' even though generated during worst case compliance testing 
conditions for other parameters.
    To evaluate these revised data for the purpose of determining a 
MACT floor, the Agency used the following data analysis steps: (1) Rank 
Hg emissions from lowest to highest; (2) conduct a breakpoint analysis 
on the ranked Hg emissions data, and (3) establish the floor standard 
equal to the test condition average of the breakpoint source. The 
breakpoint analysis reflects an engineering evaluation of the data and 
ensures that the one source that spiked elevated quantities of Hg did 
not drive the floor level upward to levels higher than the 
preponderance of this ``normal'' data indicates is routinely 
achievable. The Agency's analysis results in a MACT floor level of 47 
g/dscm. The revised database indicates that approximately 75 
percent of LWAKs are achieving this floor level.
    b. BTF considerations for existing sources. The Agency originally 
considered a BTF standard based on flue gas temperature reduction to 
400  deg.F or less followed by ACI, but determined that a BTF level 
would not be warranted.
    EPA continues to believe that flue gas temperature reduction to 400 
 deg.F followed by ACI is the appropriate BTF control option for 
improved Hg control at LWAKs. As discussed above for existing CKs, we 
have assumed an ACI effectiveness of 60 percent in identifying BTF 
levels for LWAKs for the purposes of today's analysis. Thus, the BTF 
standard is 15 g/dscm which is based on a ACI efficiency of 60 
percent applied to the floor level of 33 g/dscm. Going to a 
BTF standard of 15 g/dscm for mercury is consistent with the 
range examined in the proposal.

[[Page 24233]]

However, at proposal, significant cost-effectiveness issues were raised 
(and commented extensively on). It is likely that those same issues 
would arise here with respect to a BTF standard of 15 g/dscm.
    c. MACT floor for new sources. At proposal, the Agency identified 
floor control as hazardous waste feedrate control not to exceed an MTEC 
of 17 g/dscm--the same as existing sources. Thus, EPA proposed 
an identical floor standard of 72 g/dscm.
    For the same reasons discussed for existing LWAKs, the Agency 
believes that the most appropriate engineering evaluation and data 
analysis method to identify the floor level is identical to the 
analysis done for existing sources. Thus, the MACT Floor standard would 
be 47 g/dscm for new LWAKs.
    d. BTF considerations for new sources. The Agency considered a BTF 
standard for new sources based on ACI, but determined that it would not 
be cost-effective to adopt the BTF standard. The Agency continues to 
consider the use of ACI as the BTF technology. In evaluating the 
revised database, EPA has identified a level of 15 g/dscm as 
the BTF standard for new sources based on ACI and flue gas temperature 
reduction to 400  deg.F or less. This is based on a source achieving 
the MACT new floor level of 33 g/dscm and then applying ACI 
with a 60 percent removal efficiency. Again, in light of the reasons 
identified for existing sources, the Agency has concerns as to whether 
a BTF level based on ACI will ultimately be warranted for new LWAK 
sources.
    3. Particulate Matter (PM). a. MACT Floor for Existing Sources. At 
proposal, EPA defined floor control as a fabric filter with an air-to-
cloth ratio of 2.8 acfm/ft \2\. The MACT floor was 0.049 gr/dscf.
    In evaluating the revised database, we examined a refined 
engineering evaluation and data analysis method to identify a MACT 
floor. This evaluation was a four-step process: (1) Rank all PM 
emissions data and identify the MACT floor controls used by the best 
performing 6 percent of sources. (2) Develop the expanded universe to 
include all sources employing MACT control, without further 
characterizing MACT control (e.g., air-to-cloth ratio of the fabric 
filter) as done in the proposal because we do not have sufficient data 
on the detailed design, operating, and maintenance characteristics 
related to test conditions in the revised database. Since all LWAKs use 
fabric filters for PM control, all test condition data are included in 
the expanded universe. (3) For each PM test condition, evaluate the 
corresponding SVM SRE and screen out sources that have relatively poor 
SREs (i.e., outliers above a breakpoint in the data array), which is an 
indicator of poor design, operation, and maintenance characteristics of 
the MACT controls at the source. (4) Identify the MACT floor equal to 
the highest test condition average of all test conditions in the PM 
expanded universe.
    The Agency's evaluation of the LWAK PM data results in a MACT floor 
of 0.022 gr/dscf. All LWAK test condition data are achieving 0.022 gr/
dscf.
    LWAKs typically operate at higher stack oxygen concentrations 
compared to other combustion systems due to the LWAK manufacturing 
process (e.g., excess air is forced into the kiln to aid in the 
expansion of the raw material into lightweight aggregate). Typical 
stack oxygen concentrations range from 12 to 16 percent, while CKs, for 
example, typically range from 3 to 8 percent. Since the standards are 
expressed at 7 percent oxygen, the floor standard of 0.022 gr/dscf 
would be equivalent to 0.014 gr/dscf at 12 percent oxygen and 0.008 gr/
dscf at 16 percent oxygen under the conditions that LWAKs typically 
operate.
    In the NPRM, the Agency proposed that sources maintain continuous 
compliance with the PM standard through the use of a PM CEMS. A 
decision whether to require LWAKs to install a PM CEMS will be made at 
the completion of an on-going demonstration testing program to 
determine if at least one PM CEMS can meet the proposed performance 
specifications. Since the floor standard discussed above was based on 
manual test method data, the Agency will re-evaluate at the completion 
of the CEMS testing program whether these PM floor standards would be 
appropriate in the event that the final rulemaking requires continuous 
compliance with a PM CEMS. The Agency will notice the results and 
conclusions of the demonstration test program in the docket for the HWC 
rule.
    b. BTF considerations for existing sources. In the NPRM, the Agency 
proposed a BTF level of 0.030 gr/dscf and solicited comment on an 
alternative BTF level of 0.015 gr/dscf based on improved PM control.
    Based on the revised database, we can evaluate a reduced PM 
emissions level lower than 0.022 gr/dscf as the BTF standard (in 
conjunction with BTF reductions in SVMs and LVMs). This would require 
an improved PM collection technology such as the use of more expensive 
fabric filter bag material. Given that the alternative floor level 
analysis presented today would be substantially lower than the proposed 
floor and BTF levels, significant cost-effectiveness considerations 
come into play and suggest that BTF levels may not ultimately prove to 
be warranted.
    c. MACT floor for new sources. At proposal, EPA defined floor 
control for new sources as a fabric filter with an air-to-cloth ratio 
of 1.5 acfm/ft \2\. The MACT floor was 0.054 gr/dscf.
    Based upon evaluation of the revised database, the floor control 
and emission level discussed above for existing sources would also 
appear to be appropriate for new sources. Therefore, MACT floor control 
is a well-designed and properly operated fabric filter, and the MACT 
floor for new LWAKs is 0.022 gr/dscf.
    d. BTF considerations for new sources. In the NPRM, EPA proposed a 
BTF standard of 0.030 gr/dscf based on improved PM control, which was 
consistent with existing sources.
    Today, as discussed above for existing source BTF considerations 
and based upon examining the revised database in light of the findings 
at proposal, a BTF standard for new sources beyond 0.022 gr/dscf (and 
corresponding BTF reductions for SVMs and LVMs) would not appear to be 
cost-effective.
    4. Semivolatile Metals (SVM) (cadmium and lead). a. MACT floor for 
existing sources. At proposal, EPA defined floor control as either (1) 
a fabric filter with an air-to-cloth ratio of 1.5 acfm/ft \2\ with a 
hazardous waste (HW) MTEC less than 270,000 g/dscm, or (2) a 
combination of a fabric filter and venturi scrubber with an air-to-
cloth ratio of 4.2 acfm/ft \2\ and a HW MTEC less than 54,000 
g/dscm. The proposed floor level was 12 g/dscm.
    LWAKs use a combination of good PM control and limiting hazardous 
waste feedrates to control SVM emissions. SVMs are controlled most 
efficiently by technologies which are effective at capturing fine PM, 
such as fabric filters which are employed by all LWAKs. EPA's revised 
database shows that SVM emissions vary substantially from 3 to over 
1600 g/dscm with 60 percent below 80 g/dscm and the 
remaining 40 percent above 400 g/dscm.
    The refined data analysis method used by EPA to evaluate and 
identify a MACT floor would be based directly on the results from the 
PM floor analyses discussed above. As mentioned there, 0.022 gr/dscf 
would appear to represent the MACT floor for LWAKs based on good PM 
control. Since SVMs are controlled, in part, by a well-designed and 
operated PM control devices, it follows that sources achieving this PM

[[Page 24234]]

performance level should also be controlling SVMs emissions.
    Therefore, in its refined SVM analyses of the revised database, the 
Agency would first consider all SVM data when corresponding PM 
measurements are below 0.022 gr/dscf. To identify the SVM floor from 
these data, we identify either at the highest SVM test condition 
average or the level that excludes sources achieving substantially 
poorer SVM control than the majority of sources. It is most likely 
appropriate to use the latter approach--excluding sources with 
significantly poorer SVM performance--because their higher SVM 
emissions may be the result of exceedingly high SVM feedrates or some 
other factor which is not able to be discerned from the data available 
to the Agency. An SVM emissions breakpoint analysis is the approach for 
excluding these poorer performing test conditions.
    Applying this evaluation technique to the revised LWAK SVM database 
results in a MACT floor of 76 g/dscm. Approximately 62 percent 
of LWAK SVM test condition data are currently achieving this emissions 
level.
    Finally, as discussed in an earlier section, a preliminary analysis 
indicates that MACT standards may not be warranted for one HAP metal, 
antimony. Since the number of metals being considered for MACT 
standards may change, we are investigating the appropriate structure of 
metals standards (e.g., retain the volatility groups or establish 
individual metals standards). Using the refined method discussed above 
for SVM, we analyzed the revised database with respect to Cd and Pb 
data. The floor analysis corresponding to PM measurements below 0.022 
gr/dscf would result in the following floor levels: Cd 53 g/
dscm, and Pb 67 g/dscm.
    b. BTF considerations for existing sources. In the NPRM, the Agency 
considered a BTF standard for SVMs based on improved PM control. 
However, the Agency concluded that a BTF standard would not be cost-
effective given that the SVM floor level of 12 g/dscm alone 
would result in an estimated 97 percent SVM reduction in emissions.
    As discussed for PM BTF considerations, the Agency also re-
evaluated the possible appropriateness of using a reduced PM emissions 
level based on improved PM control as a BTF standard (with 
corresponding BTF reductions in SVMs and LVMs). Even though the 
alternative SVM floor standard is higher than at proposal, our 
preliminary judgement is that significant cost-effectiveness 
considerations will be nonetheless encountered in a final analysis of 
whether to establish a BTF standard for SVMs or for Pb or Cd 
individually.
    If, however, the revised risk assessment yet to be conducted would 
show significant risk at a SVM floor standard of 76 g/dscm, 
which would be the floor level resulting from application of the data 
analysis method discussed above, the Agency will determine whether a 
BTF standard based on control of SVM feedrate to levels below those at 
the floor would be appropriate. This feedrate limitation would in turn 
reduce SVM emissions. The BTF standard and the corresponding level of 
feedrate control would be dictated by considerations of cost-
effectiveness and the need to establish more stringent RCRA-related 
controls.
    c. MACT floor for new sources. At proposal, EPA defined floor 
control as a fabric filter with an air-to-cloth ratio of 1.5 acfm/ft 
\2\ with a hazardous waste (HW) MTEC less than 270,000 g/dscm. 
The proposed floor level was 5.2 g/dscm.
    Upon evaluation of the revised database, EPA believes that the 
floor control and emission level discussed above for existing sources 
for SVMs would also be appropriate for new sources. In this event, MACT 
floor control would be a well-designed, operated and maintained PM 
control device (e.g., fabric filter) achieving the PM floor level of 
0.022 gr/dscf. The Agency's evaluation of the SVM data results in a 
MACT floor of 76 g/dscm.
    Finally, based on the revised database, individual metal floor 
levels for new sources are identical to those for existing sources. 
Thus, individual Cd and Pb standards are 53 g/dscm for Cd and 
67 g/dscm for Pb.
    d. BTF considerations for new sources. In the NPRM, the Agency 
considered a SVM BTF level, but determined that a BTF standard would 
not be cost-effective.
    As discussed for existing sources, the Agency considered a more 
stringent PM emissions level for improved control of PM, SVM and LVM 
emissions for new LWAKs in light of the revised database. Even though 
the SVM floor standard is higher than at proposal, as discussed above, 
cost-effectiveness issues are again raised and suggest that a BTF 
standard for either SVMs or for Pb or Cd individually based on improved 
PM control may likewise ultimately prove to be inappropriate.
    5. Low Volatile Metals (LVM) (arsenic, beryllium, and chromium) a. 
MACT Floor for Existing Sources. At proposal, EPA defined floor control 
as a fabric filter with an air-to-cloth ratio of 1.8 acfm/ft \2\ with a 
HW MTEC less than 46,000 g/dscm.
    The proposed floor level was 340 g/dscm, which included 
antimony.
    LWAKs use a combination of good PM control and limiting hazardous 
waste feedrates to control LVM emissions. LVMs are less likely to 
vaporize at combustion temperatures and therefore partition primarily 
to the residue or adsorb onto particles in the combustion gas. EPA's 
database shows that LVM emissions vary from around 20 to 285 
g/dscm.
    The engineering evaluation data analysis method used by EPA to 
evaluate the revised database and identify a MACT floor for LVMs is 
also related directly to the PM floor analysis. As was determined in 
the PM analysis, a floor of 0.022 gr/dscf represents MACT for LWAKs 
based on good PM control. Considering all LVM data from sources 
achieving a PM level 0.022 gr/dscf or better, EPA's evaluation of the 
revised LWAK data results in a LVM floor of 37 g/dscm 
(excluding sources above a breakpoint and therefore achieving 
substantially poorer LVM emissions than the majority of sources). 
Approximately 71 percent of LWAK LVM test condition data are currently 
achieving this emissions level.
    Finally, as discussed for SVMs, EPA is continuing to investigate 
the appropriate structure of metals standards (e.g., retain the 
volatility groups or establish individual metals standards). The Agency 
analyzed individual As, Be, and Cr (hexavalent) data and established 
individual metal floor levels consistent with the engineering 
evaluation and data analysis method. Where PM measurements are below 
0.022 gr/dscf, the result would be: As 22 g/dscm, Be 3 
g/dscm, and Cr (hexavalent) 6.2 g/dscm.
    The Agency is concerned that some of the potential floor standards 
for some individual metals (e.g., Be, Cr (hexavalent)) may be present 
at levels approaching practical quantitation limits (PQLs). PQLs are 
the lowest level of quantification that the Agency believes a competent 
analytical laboratory can be expected to reliably achieve. The Agency 
will investigate whether this issue may need to be addressed in the 
development of any individual metals standards that may be considered 
for the final rulemaking. We invite comment on the issue of PQLs and 
LVM BTF standards.
    b. BTF considerations for existing sources. In the NPRM, the Agency 
considered a BTF standard for LVMs based on improved PM control. 
However, the Agency concluded that a

[[Page 24235]]

BTF standard would not be cost-effective.
    As discussed for PM BTF considerations, the Agency also re-
evaluated the possible appropriateness of using a reduced PM emissions 
level based on improved PM control as a BTF standard (with 
corresponding BTF reductions in SVMs and LVMs). Considering that the 
alternative LVM floor standard would be lower than at proposal, our 
preliminary judgment is that significant cost-effectiveness 
considerations will likely be encountered in a final analysis of 
whether to establish a BTF standard for either LVM or for As, Be, or Cr 
(hexavalent) individually.
    c. MACT floor for new sources. At proposal, EPA defined floor 
control as a fabric filter with an air-to-cloth ratio of 1.3 acfm/ft 
\2\ with a hazardous waste (HW) MTEC less than 37,000 g/dscm. 
The proposed floor level was 55 g/dscm.
    Based upon our re-evaluation of the database, the floor control and 
emission level discussed above for existing sources for LVMs would also 
appear to be appropriate for new sources. MACT floor control is a well-
designed and properly operated PM control device (i.e., fabric filter) 
achieving the PM floor level of 0.022 gr/dscf. The Agency's evaluation 
of the LVM data would result in a MACT floor of 37 g/dscm.
    Finally, individual metal floor levels for new sources are 
identical to those for existing sources. Thus, the standards would be: 
As 22 g/dscm, Be 3 g/dscm, and Cr (hexavalent) 6.2 
g/dscm.
    d. BTF considerations for new sources. In the NPRM, the Agency 
considered a LVM BTF level, but determined that a BTF standard would 
not be cost-effective.
    As discussed for existing sources, the Agency considered a more 
stringent PM emissions level for improved control of PM, SVM and LVM 
emissions for new LWAKs. Because the alternative PM and LVM floor 
levels presented today are lower and approximately equivalent, 
respectively, than the proposed floors, a BTF standard for either LVMs 
or individual As, Be, or Cr (hexavalent) standards based on improved PM 
control may be inappropriate in light of the cost-effectiveness 
concerns inherent in this scenario.
    6. Hydrochloric Acid and Chlorine (HCl/Cl2) a. MACT 
floor for existing sources. At proposal, the Agency identified floor 
control for total chlorine as either: (1) Hazardous waste feedrate 
control of chlorine to a MTEC of 1.5 g/dscm or less; or (2) venturi 
scrubber with hazardous waste MTEC of 14 g/dscm or less. The proposed 
floor emission level was 2100 ppmv.
    Upon evaluation of the revised database, the data analysis method 
used at proposal appears still to be appropriate and, consequently, 
floor control would be defined virtually the same as at proposal. 
However, EPA no longer thinks it appropriate to add a computed 
emissions variability factor to the standard-setting test condition for 
large data sets 44. Thus, the floor emission level would be 
1300 ppmv rather than 2100 ppmv.
---------------------------------------------------------------------------

    \44\  See discussion in Part Two, Section II.D.
---------------------------------------------------------------------------

    b. BTF considerations for existing sources. At proposal, the Agency 
defined BTF control as wet or dry lime scrubbing with a control 
efficiency of 90 percent and proposed a BTF standard of 450 ppmv.
    The Agency continues to believe that wet or dry lime scrubbing can 
achieve at least 90 percent removal of HCl/Cl2. Therefore, the revised 
BTF standard would be 130 ppmv assuming that the requisite cost-
effectiveness information continues to suggest that a BTF standard is 
warranted. The two LWAKs that are equipped with wet scrubbers achieved 
emission levels below 45 ppmv.
    c. MACT floor for new sources. At proposal, the Agency defined MACT 
floor control for new sources as a venturi scrubber with a hazardous 
waste MTEC of 14 g/dscm or less, and identified a floor level of 62 
ppmv.
    As for existing sources, the data analysis method used at proposal 
for new sources is appropriate and, consequently, floor control for new 
sources would be defined the same as at proposal. Excluding a computed 
emissions variability, the floor emission level would be 43 ppmv rather 
than 62 ppmv.
    d. BTF considerations for new sources. The Agency did not propose a 
BTF standard for new sources because the floor standard was based on 
best available control technology: wet scrubbing. We have no new 
information in the revised database that would indicate that this 
conclusion at proposal should be revisited.
    7. Carbon Monoxide (CO). The Agency proposed a MACT standard for CO 
of 100 ppmv based on a hourly rolling average (HRA). We continue to 
believe that this standard is appropriate for the reasons expressed in 
the preamble to the proposal.
    8. Hydrocarbons (HC). The Agency proposed a HC level of 14 ppmv 
based on floor control using good combustion practices. Although we 
continue to believe that floor control is good combustion practices, 
our engineering evaluation of the revised database suggests that a 
floor standard of 10 ppmv, HRA, may be more appropriate. The single 
LWAK facility in the revised emissions database that could not achieve 
a HC standard of 10 ppmv (perhaps because of trace organics in the raw 
material) has stopped burning hazardous waste. Data from that facility 
have been excluded in the revised analysis. Although the remaining 
LWAKs appear to be able to meet a HC standard on the order of 6 ppmv, 
it may be more appropriate to establish the standard at 10 ppmv. This 
is because we are not aware of an engineering reason that LWAKs using 
good combustion practices should be able to achieve lower HC emissions 
than incinerators. Given that the incinerator HC standard would be 10 
ppmv, that standard also appears to be appropriate for LWAKs.

Part Three: Implementation

I. Compliance Date Considerations

    The Agency proposed that all sources subject to the final rule be 
in compliance with the final standards three years following the 
effective date of the rule (61 FR 17416). The proposed compliance 
period is consistent with the CAA, which defines the maximum compliance 
period for sources regulated under the statute as three years, with the 
possibility of a one-year extension for those sources that adequately 
demonstrate a need for additional time for the installation of emission 
controls. The Agency proposed the maximum compliance period allowed by 
the Act because this rule will likely require the majority of units, 
currently operating under RCRA regulations, to undergo substantial 
modifications to come into compliance with the potentially more 
stringent final MACT standards.
    The general provisions of 40 CFR Part 63 do not require a 
demonstration of compliance until 240 days following the compliance 
date. This 240 day period between the compliance date and the 
demonstration of compliance is clearly not appropriate for HWCs because 
these devices are presently regulated under RCRA via enforceable 
operating limits, and in this interim period the enforceable operating 
limits would be undefined (61 FR 17415).
    Therefore, to provide consistency with the currently-applicable 
RCRA regulatory compliance scheme, the Agency departed from the general 
requirements applicable to MACT sources and proposed a revised 
definition of compliance date. The proposed definition of compliance 
date would require sources to complete installation of controls and to

[[Page 24236]]

successfully complete performance testing and certify compliance within 
the three-year compliance period, not by a date 240 days after the 
three-year compliance period. Id. In addition to the revised definition 
of compliance date, the Agency also proposed a number of extra 
consequences for HWC sources that are not in compliance by the 
compliance date: (1) Immediate termination of waste-burning activities; 
(2) loss of RCRA permit or interim status; (3) a requirement to obtain 
a new RCRA permit; and (4) compliance with MACT standards for new 
sources.
    In response to the proposal, the Agency received comments 
suggesting the three-year compliance period would be impossible to meet 
due to a number of competing factors, and that more time would be 
necessary to comply with the rule. These factors included permit 
modification, installation of controls, and documentation of 
compliance. Furthermore, commenters expressed serious concerns about 
combining these factors with the consequences of missing the compliance 
date. Industry commented that under this proposed approach facilities 
engaged in legitimate efforts to comply with the standards would be 
forced to terminate waste-burning activities, and be subjected to 
burdensome consequences that are unnecessary to protect the environment 
or ensure the public's safety.
    However, EPA has become persuaded by commenters concerns regarding 
the ability of HWC sources in particular to comply with the proposed 
standards by the compliance date. Sources will have to modify their 
RCRA permits. Further, some sources may choose to pursue waste 
minimization strategies. For these reasons, the Agency is considering 
certain actions that may be finalized in advance of the final HWC rule 
such as, the streamlined permit modification procedures discussed at 
17455 in the proposal; as well as, the waste minimization option for 
extension of the compliance date to allow for the application of waste 
minimization controls to meet the final standards discussed at 17417. 
The streamlined permit modification procedures would reduce the 
administrative requirements and time necessary to begin modification 
procedures required to comply with the final standards. The waste 
minimization compliance date extension option, which provides an 
additional avenue for facilities to request an extension of the 
compliance date, would afford facilities that choose to institute waste 
minimization measures an additional year to complete these actions.
    However, even with the special provisions under consideration, 
sources may require the full amount of time allowed under the CAA to 
comply. Therefore, the Agency is also considering a revised 
implementation scheme that will allow for a simplified approach 
consistent with the implementation of general CAA-MACT rules. This 
approach would provide both additional relief to sources complying with 
the final rule, and information regarding a source's compliance status 
on the compliance date for the Agency. The specifics of this new option 
are explained in greater detail in the following paragraphs. Comments 
are requested on this new approach to implementing the HWC MACT 
standards.
A. Definition of Compliance Date
    Today, the Agency is considering a revision to the proposed 
definition of compliance date. Under this revised approach, HWC sources 
would follow the CAA-MACT schedule for demonstration of compliance, 
through MACT performance testing and submission of test results, 
contained in Sec. 63.7. Under that section, affected sources must 
conduct performance tests within 180 days following the compliance 
date, and submit the results of the tests 60 days following the 
completion of the performance test.45 This CAA-based 
approach responds to the comments questioning our revised definition of 
compliance date and would achieve a more consistent implementation 
framework. However, because the Agency is concerned about the 
compliance status of affected sources on the compliance date, the 
Agency also seeks comment on provisions to enhance the general 
requirements for HWCs with a requirement for the submission of a 
``precertification of compliance'' in the final rule. A 
precertification of compliance would require facilities to precertify 
their compliance status on the compliance date. The details of the 
precertification of compliance are described in greater detail in the 
following paragraphs.
---------------------------------------------------------------------------

    \45\ In the HWC proposed rule, however, the Agency allowed 
sources 90 days to submit test results because D/F analyses can 
require more time than traditional MACT analyses. We continue to 
believe that this 90-day allowance is appropriate.
---------------------------------------------------------------------------

B. Pre-Certification of Compliance
    Today the EPA is seeking comment on an option which would require 
sources to submit a notification to regulatory agencies that details 
the operating limits a unit will be operated under in the interim 
period following the compliance date but before the results of the 
initial comprehensive performance test are submitted. This 
notification, the precertification of compliance, would include all of 
the information necessary to determine the compliance status of an 
affected source (e.g., automatic waste feed cutoff limits, feedrate 
limits, emission control device operating limits, etc.) during the 240 
day period after the compliance date. At a minimum, the facility would 
be required to establish operating limits on all of the parameters 
identified in the proposed monitoring requirements found in table V.2.1 
at 17419 of the proposed rule. This approach is appropriate because 
these facilities are already regulated under RCRA. There should not be 
any ambiguity for these facilities in terms of being between regulatory 
regimes at any point in time.
    The operating limits in the precertification of compliance would be 
enforceable limits.46 However, if following the initial 
comprehensive performance test, the facility's precertification of 
compliance designated operating limits are found to have been 
inadequate to ensure compliance with the MACT standards, the facility 
will not be deemed out of compliance with the MACT emissions standards. 
EPA invites comment on this approach, and specifically invites comment 
on the necessity of establishing operating limits on the entire set of 
parameters identified in table V.2.1.
---------------------------------------------------------------------------

    \46\ The Agency notes that under this scheme facilities are 
still subject to the RCRA emission limitations, and the associated 
operating limits and enforcement actions until removal of the air 
emission limitations from the RCRA permit. However, because on the 
compliance date all facilities must be compliance with the emission 
standards of the final MACT rule, the Pre-COC operating limits, 
which are expected to be more stringent than current RCRA emission 
standards, take precedence over the RCRA permit limits except where 
the RCRA permit limits are based on a more stringent standard 
adopted under the Omnibus provisions of RCRA section 3005. 
Furthermore, EPA notes that compliance with Pre-COC operating limits 
that are based on standards that are more stringent than RCRA 
emission standards assures compliance with the RCRA based emission 
standards.
---------------------------------------------------------------------------

C. Consequences of Non-compliance
    As mentioned earlier, the Agency proposed a number of serious 
consequences that would befall a source that misses the compliance date 
(61 FR 17416). The Agency proposed these consequences to provide an 
incentive for affected sources to move swiftly to comply with the final 
standards. In response to the proposal, through written comments from 
industry and during round table discussions with

[[Page 24237]]

affected parties, the Agency received information suggesting that 
imposition of these consequences through regulatory language was 
unnecessary. Consequently, the Agency is considering deleting those 
specific consequences from the regulatory language and relying on the 
regulating agency's policy regarding enforcement response to govern the 
type of enforcement response at a facility that fails to meet the 
compliance deadline.
    Upon review of this enforcement process, the Agency is presently 
inclined to apply the normal CAA enforcement procedures to non-
compliant sources in the final rule for hazardous waste combustors.

II. Compliance Requirements

    In this section, we discuss several compliance issues: (1) 
Compliance with carbon monoxide (CO) and/or HC emission standards; (2) 
compliance with a startup, shutdown, and malfunction plan when not 
burning hazardous waste; (3) metals extrapolation and interpolation 
considerations; (4) site-specific variances for cement kilns and LWAKs 
because of inability to meet the standards solely due to metals or 
chlorine in raw materials; and (5) emissions averaging for cement kilns 
with unique design or operating features.
A. Compliance With CO and/or HC Emission Standards
    The Agency proposed MACT emission standards for both CO and HC for 
incinerators and LWAKs as surrogates to control emissions of organic 
HAPs. Cement kilns would be required to comply with either a CO or HC 
standard because of raw material considerations. See 61 FR at 17375-6. 
The Agency explained that relying on only CO or HC alone appeared to 
have drawbacks, and thus proposed that incinerators and LWAKs comply 
with emissions standards for both. Nonetheless, the Agency acknowledged 
that requiring compliance with standards for both CO and HC may be 
unnecessarily redundant, and requested comment on the following 
alternative approaches: (1) Giving sources the option of complying with 
either CO or HC; or (2) establishing a MACT standard for either CO or 
HC, but not both.
    Although the Agency is continuing to evaluate comments and options 
\47\ on how to limit CO and/or HC to control organic HAPs, we invite 
comment on an additional feature of the first option whereby a source 
can elect to comply with either the CO or HC standard. Under this 
approach, a source that elects to comply with the CO standard (rather 
than the HC standard) would be required to document during the 
performance test compliance with the HC limit. This is necessary 
because we have some (limited) data that show a source can have HC 
levels exceeding the standard discussed in today's notice while meeting 
the CO limit. Even though the vast majority of the data indicate that 
HC will be low when CO levels are low, a requirement to confirm this 
relationship on a site-specific basis may be warranted.
---------------------------------------------------------------------------

    \47\ We are also evaluating another option whereby compliance 
with the HC limit would be required, and a site-specific CO limit 
(but not lower than 100 ppmv, the proposed MACT standard) would also 
be established. This option would provide assurance that HC 
emissions are within allowable levels, and by also limiting CO, it 
would give the operator advance notice of a potential increase in HC 
levels, thus helping to avoid an exceedance of the HC standard.
---------------------------------------------------------------------------

    To confirm the relationship during the performance test, the source 
would use a portable HC monitor to document that HC levels are below 
the MACT standard. This is not expected to be a burdensome test. 
Further, however, to ensure that the CO/HC relationship is maintained 
over the range of operating conditions that the facility may ultimately 
employ, we are considering whether to require the source to establish 
limits on key operating parameters than can affect combustion 
efficiency (and thus HC emissions). The limits would be established 
based on parameter values observed while demonstrating the CO/HC 
relationship during the performance test.
    We specifically request comment on which key parameters should be 
limited to ensure that the CO/HC relationship is maintained. Further, 
we request comment on whether these key parameters should be identified 
on a national basis or a site-specific basis during review of the 
performance test protocol. In providing comment, note that the Agency 
has already proposed to establish site-specific limits on several 
combustion-related parameters to ensure compliance with the D/F 
emission standard (e.g., minimum combustion chamber temperature; 
maximum waste feedrate; and for batch fed units, maximum batch size and 
feeding frequency, and minimum oxygen concentration in the combustion 
gas). In addition, note that it may be appropriate to identify as key 
parameters (for purposes of ensuring that the CO/HC relationship is 
maintained) those parameters for which limits are currently established 
during destruction and removal efficiency (DRE) testing, including: (1) 
Minimum combustion temperature at each combustion chamber or feed 
location; (2) minimum combustion gas residence time (i.e., maximum 
combustion gas velocity, or appropriate surrogate); and (3) minimum 
combustion gas oxygen concentration. If the Agency determines that DRE 
testing is not necessary for some types of sources as discussed in 
Section III below, testing to document the CO/HC relationship would be 
used to establish limits on these heretofore DRE-limited parameters.
B. Startup, Shutdown, and Malfunction Plans
    The Agency proposed that startup, shutdown and malfunction plans 
are not necessary for hazardous waste combustion sources because the 
allowances that such plans provide are not appropriate for hazardous 
waste combustors (61 FR 17449). Specifically, the Agency stated that 
EPA did not need information regarding how quickly a source is able to 
correct a malfunction to come back into compliance with the standards 
because affected sources cannot burn waste unless the source is in 
compliance with all applicable standards.
    However, in comments, the Agency was informed of a few situations 
in which it is appropriate for sources to comply with a startup, 
shutdown, and malfunction plan. These situations include those in which 
sources temporarily stop burning hazardous waste but intend to resume 
burning hazardous waste in the near future. The examples presented to 
the Agency involve production units (i.e., cement kilns, LWAKs, and 
possibly on-site incinerators equipped with waste heat boilers to 
generate steam or heat at a chemical production facility) that must 
continue operations following waste feed cutoff to maintain production 
at the facility. Also, commenters cited temporary shutdowns necessary 
for planned maintenance to be performed on the unit.
    In light of these comments, the Agency is rethinking its proposed 
approach and requests comment on a requirement for sources to comply 
with the provisions listed in Sec. 63.7 regarding startup, shutdown and 
malfunction plans, including the reporting requirements of 
Sec. 63.10(d)(5)(I). These provisions would apply at HWCs when waste is 
not being fed or does not remain in the combustor, excluding automatic 
waste feed cutoff events.
    Sources would be subject to the standards at all times, and the 
malfunction plan would only apply during times when the source is 
either temporarily not burning waste or when

[[Page 24238]]

waste no longer remains in the combustor. For example, if a source is 
temporarily not burning waste and a malfunction occurs that is followed 
by an exceedance of an applicable standard, the source will not be in 
violation as long as it is complying with the procedures outlined in 
the malfunction plan. On the other hand, if a source is burning waste 
and a malfunction occurs that necessitates an automatic waste feed 
cutoff followed by an exceedence of a standard, the source would be in 
violation regardless of whether the source is complying with the 
malfunction plan.\48\
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    \48\ This situation would be considered a violation unless the 
source can document that the exceedance occurred after waste was no 
longer in the combustor and the residuals of the waste combustion 
process had been treated by the pollution control equipment.
---------------------------------------------------------------------------

    Therefore, under this option, a source may develop a malfunction 
plan that details the situations in which the source is intentionally 
not feeding waste, or that details the situations when certain emission 
control devices will not be in operation.
C. Metals Extrapolation and Interpolation Considerations
    In the NPRM, the Agency discussed the operating conditions under 
which a source will likely operate to demonstrate compliance with the 
metals emission limits identified in the proposed rule (61 FR at 17428-
30). The Agency also acknowledged in the proposal that operators will 
likely want to operate their units during comprehensive performance 
tests close to the edge of the operating envelope so that they can 
comply with the emission standards and still achieve the necessary 
operational flexibility required by the facility. EPA further stated 
that, to achieve a sufficient level of operational flexibility, sources 
could be expected to engage in the spiking of metals into the waste 
matrix, which is a practice that concerns the Agency. EPA's concern 
extends to the overall metals loading to the environment (for example, 
Hg and Pb), exposure of facility employees, and exposure of surrounding 
community to higher than normal metals concentrations due to testing 
procedures that are for the purposes of developing waste feedrate 
limits and operational flexibility.
    Therefore, the Agency has investigated approaches that may provide 
a method to afford additional metals feedrate flexibility without the 
need of high metals spiking (otherwise necessary to identify a metals 
feedrate for an associated metals emission level).\49\ One promising 
approach would use a statistical extrapolation methodology.\50\
---------------------------------------------------------------------------

    \49\ See USEPA, Draft Technical Support Document for HWC MACT 
Standards (NODA), Volume III: Evaluation of Metal Emissions Database 
to Investigate Extrapolation and Interpolation Issues, April 1997.
    \50\ Extrapolations would be based on applying a conservative 
``universal variability factor'' (UVF) multiplier to the test 
condition average. The UVF is based on evaluating within-test 
condition emissions variability for each metal in the Agency's trial 
burn and BIF certification of compliance metal emissions database. 
It represents (in log form) a ``residual'' level that 95 percent of 
the residual population is below, where the residual is defined as 
the difference between the log of the emission level for each test 
condition run and the log of the test condition average. The UVF 
would range from 3x to 5x depending on the volatility grouping for 
the metal. Given the conservatism of the UVF, a less conservative 
approach would be used (i.e., melding extrapolating using the UVF 
with extrapolating from the highest run in a test condition) to 
extrapolate to feedrate and emission levels close to levels actually 
tested.
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    Under this approach a source would use the metal feedrates and 
emission rates associated with a MACT performance test to extrapolate 
to higher allowable feedrates and emission rates. The Agency believes 
that the upward extrapolation procedure developed can conservatively be 
used to allow for higher metals feedrate limits, but still ensure that 
the facility is well within any applicable MACT (or RCRA) emissions 
limit.\51\ Although downward interpolation (i.e., between the measured 
feedrate and emission level and zero) was also investigated, the Agency 
is concerned that downward interpolation may not be conservative 
primarily because system removal efficiency decreases as metal feedrate 
decreases. Thus, projected emissions at lower feedrates may in fact be 
lower than actual emissions. Consequently, the Agency is not inclined 
to allow downward interpolation.
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    \51\ Under the extrapolation approach, sources would be required 
to feed metals at no less than normal rates to narrow the amount of 
extrapolation sought. Further, we expect that some spiking would be 
desired to increase confidence in the measured feedrate levels that 
will be used to project higher allowable feedrates (i.e., the errors 
associated with sampling and analyzing heterogeneous wastestreams 
can be minimized by spiking known quantities). However, the Agency 
does not want sources to extrapolate to allowable feedrates that are 
significantly higher than their historical range of feedrates (i.e., 
extrapolated feedrates should be limited close to the historical 
levels that a source actually fed). This may work to limit the 
practical utility of extrapolation.
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    The Agency expects that any extrapolation methodology would be 
reviewed and approved by regulatory officials. Sources would request 
approval to extrapolate feedrates as part of the performance test plan 
that would be submitted at least 60 days prior to the test date. See 
Sec. 63.7(b) and (c) and proposed Sec. 63.1208. The review would 
consider in particular whether: (1) Performance test metal feedrates 
were appropriate (e.g., whether feedrates were at least at normal 
levels; depending on the heterogeneity of the waste, whether some level 
of spiking would be appropriate; and whether the physical form and 
species of spiked material is appropriate); and (2) whether the 
requested, extrapolated feedrates were warranted considering historical 
metal feedrate data. In addition, regulatory officials would review the 
performance test results in making a finding of compliance required by 
Sec. 63.6(f)(3) to ensure that emission test results have been 
interpreted properly and that the extrapolation procedure is 
appropriate for the source.
    The Agency is discussing this approach with some hesitation because 
facilities would be able to: (1) Feed metals at higher rates without a 
specific compliance demonstration of the associated metals emissions; 
and (2) obtain approval to feed metals at higher levels than normal, 
even though all combustion facilities should be trying to minimize 
metals feedrates. However, because the Agency remains concerned that 
sources would otherwise continue to feed metals during compliance 
testing at high levels,52 to it may be appropriate to 
consider this extrapolation approach as a means to reduce unnecessary 
emissions and costs incurred by facilities (and the health risk to 
testing personnel) during performance tests.
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    \52\ To achieve operational flexibility due to practical testing 
and compliance restrictions.
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    EPA invites comment on this extrapolation approach, and in 
particular, as to whether the approach is adequately conservative and 
practicable.
D. Consideration of Site-Specific Variances for Cement Kilns and LWAKs
    The Cement Kiln Recycling Coalition (CKRC) has provided comments on 
the proposed rule suggesting that two variance procedures be 
incorporated in the final rule: (1) Waiver of the Hg, SVM, LVM, and/or 
HCl/Cl2 standards when metals or chlorine in minerals and related 
process materials cause the source to exceed the standard even though 
the source is demonstrable using MACT control; and (2) waiver of the HC 
standard for the main stack of a long kiln that does not monitor CO or 
HC in the by-pass duct when organics desorbed solely from minerals and 
related process materials cause the source to exceed the standard in 
the main stack.

[[Page 24239]]

    CKRC notes that the Conference Report for the Clean Air Amendments 
of 1990 53 states that:

    \53\ H.R. Rep. No. 101-952, at p.339, 101st Cong., 2d Sess. 
(Oct. 26, 1990).
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    For categories and subcategories of sources of hazardous air 
pollutants engaged in mining, extraction, beneficiation, and 
processing of nonferrous ores, concentrates, minerals, metals, and 
related process materials, the Administrator shall not consider the 
substitution of, or other changes in, metal- or mineral-bearing raw 
materials that are used as feedstocks or materials inputs, * * * in 
setting emission standards, work practice standards, operating 
standards or other prohibitions or requirements or limitations under 
this section for such categories and subcategories.

    It should be noted that this language is not reflected in the 
legislative text, which states without caveat that MACT standards may 
be based on ``process changes, substitution of materials or other 
modifications.'' CAA section 112(d)(2)(A).54 However, 
assuming that CKRC's request for these variances has merit, and if the 
variances are incorporated in the final rule, they would apply to LWAKs 
as well given that LWAK raw materials could also cause those combustors 
to exceed the standards using MACT control. We solicit comment on 
whether these variances are appropriate and workable, and on the 
potential issues raised below.55
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    \54\ CKRC cites additional authority in its letter to B. 
Holloway and F. Behan (USEPA) of March 10, 1997 addressing these 
issues. Available in RCRA Docket # F-97-CS4A-FFFFF.
    \55\ To meet its RCRA mandate, the Agency would continue to 
evaluate emissions under the omnibus permit authority to ensure that 
controls were adequate to protect human health and the environment.
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    1. Variance for metals or chlorine in minerals and related process 
materials. It may be appropriate to waive any MACT standard for a metal 
or group of metals or the standard for HCl/Cl2 if the source documents 
that it cannot comply with the standard while using MACT control solely 
because of raw material feed. As examples, MACT control for Hg would be 
hazardous waste feedrate control at a specified MTEC. MACT control for 
SVM and LVM would also be feedrate control at a specified MTEC and 
compliance with the PM standard. A condition of the variance could be 
that the source would be required to document that the concentration of 
metal or chlorine (for which it is seeking the variance) in hazardous 
waste and any non-mineral feedstock is within the range of normal 
levels for the industry. This would ensure that metals and chlorine 
emissions attributable to non-mineral feedstreams are equivalent to 
those from sources meeting MACT.
    We therefore request comment on the following issues:
     How would normal levels be determined? What statistics 
should be used? What should be the baseline year for the determination 
(e.g., a given year (2000, or the compliance date of the rule)?
     Should the variance be granted only if the hazardous waste 
and/or non-mineral feedstreams have lower than normal levels of metals 
or chlorine? How much lower (e.g., 25th percentile levels, 40th 
percentile levels)?
     Would it be necessary to establish the normal levels in 
the rule, or should they be established initially, on a case-by-case 
basis?
     Should the Agency be concerned if levels of metals or 
chlorine in mineral feedstocks decline over time thus enabling the 
source to meet the standard? If so, what monitoring approach would be 
appropriate to identify when that occurred?
     When should variance petitions be submitted to the State 
or EPA regulatory officials (e.g., 120 or 180 days prior to the 
compliance date)?
    2. Variance for organics in minerals and related process materials.
    Although current BIF regulations limit HC levels in kilns to 20 
ppmv irrespective of the source of the hydrocarbons 56 and 
the Agency proposed to maintain that standard under MACT, CKRC notes 
that some sources have to operate inefficiently to meet the standard. 
For example, a source may have to operate back-end temperatures at 
higher than normal levels to oxidize enough of the organics being 
desorbed to meet the HC standard. This means that more fuel than normal 
must be fired to provide the extra heat at the back-end.57
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    \56\ The Agency has acknowledged that HC in the main stack of a 
long kiln can be generated by desorption of trace organics in raw 
material feedstocks as well as from fuel combustion.
    \57\ Higher back-end temperatures may be associated with higher 
rates of D/F formation.
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    CKRC has suggested approaches whereby a source can document that 
hazardous waste is being burned in compliance with either the CO limit 
of 100 ppmv or the HC limit of 10 ppmv.58 In situations 
where the kiln can monitor a representative sample of combustion gas at 
mid-kiln at least temporarily during a performance test to document 
compliance with the CO limit of 100 ppmv (or a HC limit of 10 ppmv), 
limits on key combustion parameters would be established based on 
operations during the performance test. The operating limits would be 
continuously monitored to ensure compliance with the CO or HC limits. 
Limits on the following operating parameters would be established: kiln 
gas oxygen at the kiln outlet; kiln gas residence time using raw 
material feedrate as a surrogate; and combustion zone temperature, 
using an appropriate surrogate or measured at an appropriate location.
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    \58\ Neither approach would appear to be appropriate for kilns 
that feed hazardous waste at locations other than the clinker end. 
The concern is that the kiln gas that is withdrawn for testing at 
the mid-kiln location for compliance with the CO or HC limit may not 
be representative of hazardous waste combustion gases (i.e., either 
because the hazardous waste is being fired downstream or, if the 
waste is fired at mid-kiln, the waste combustion gases may not be 
thoroughly mixed at the point of kiln gas withdrawal for CO and HC 
monitoring).
---------------------------------------------------------------------------

    CKRC also suggested that sulfur hexafluoride (SF6) could be used as 
a continuously monitored compliance parameter in lieu of limits on 
other parameters, except oxygen. This is because SF6 is recognized as a 
temperature labile compound--it is more stable than most any other 
toxic compound under a temperature-failure mode of organics 
destruction. SF6 is not, however, an indicator of oxygen-deficient 
combustion failure modes--it is destroyed at high temperatures 
irrespective of oxygen levels. Given that both adequate temperature and 
oxygen are necessary for good combustion, an oxygen limit as well as an 
SF6 feed limit and emission limit would be established under this 
option based on a performance test documenting compliance with either 
the CO or HC limits at mid-kiln.
    Finally, CKRC suggested variance approaches for the more 
problematic situation where a kiln is not able to sample kiln gas at 
mid-kiln for compliance with the CO or HC limit. One approach would be 
to allow a kiln to document compliance with the CO limit of 100 ppmv or 
the HC limit of 10 ppmv in the main stack when burning hazardous waste 
but temporarily feeding imported, low organic raw material. Under this 
approach, as with the approaches discussed above, operating limits on 
oxygen levels in kiln gas at the kiln outlet, residence time of 
combustion gas, and combustion zone temperature would be established 
based on a performance test using the low organic raw material. Also, 
continuous monitoring of limits on feedrates and emission rates (based 
on performance testing) of SF6 could be used in lieu of establishing 
limits on residence time and temperature.
E. Emissions Averaging for Cement Kilns
    Several cement kilns have unique design or operating procedures 
that warrant special consideration in

[[Page 24240]]

demonstrating compliance with the MACT standards, as discussed below.
    1. Preheater or Preheater/Precalciner Kilns with Dual Stacks. Some 
preheater or preheater/precalciner kilns are designed with separate 
main and alkali by-pass stacks. To demonstrate compliance with the 
emission standards (other than the CO/HC standards where compliance is 
based on emissions in either the main or by-pass stack), it is 
appropriate to allow such kilns to document either that both stacks 
meet the applicable emission limits, or that the stacks meet the limits 
considering flow-weighted average emissions. This is the approach 
currently used for compliance for the PM NSPS, and it is appropriate as 
well for the MACT standards that the Agency has proposed.
    2. Kilns that operate an in-line raw mill. Some cement kilns vent 
the kiln gas through the mill that grinds the raw material (i.e., raw 
mill) to help dry the raw material before charging to the kiln. Such 
designs are referred to as ``in-line raw mills''. When the raw mill is 
out of service for maintenance, approximately 10% of the time annually, 
kiln gas by-passes the mill and is vented to the stack after passing 
through the PM control device. (Stored milled raw material is charged 
during these periods of mill downtime.) The Cement Kiln Recycling 
Coalition indicates that emissions of HAPs that the Agency proposed to 
regulate can be different when gas is vented through the raw mill 
versus periods of time when the mill is out of service.59
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    \59\  CKRC Comments, August 19, 1996, pp 112-113, Docket Number 
RCSP-0170.
---------------------------------------------------------------------------

    It appears appropriate to base compliance with the MACT emission 
standards for such kilns on a time-weighted average basis. Sources 
would use historical information on utilization time for the in-line 
raw mill to document the time-weighted average and would present this 
information to regulatory officials as part of the test plan. Further, 
sources would be required to conduct performance testing under both 
operating conditions: with the raw mill on-line and off-line.

III. DRE Testing Considerations

    In the NPRM, the Agency proposed that the 99.99 percent destruction 
and removal efficiency (DRE) standard be retained under RCRA authority. 
See 61 FR at 17447. Although EPA could have proposed the DRE 
requirement as part of the MACT standards to help control organic HAPs, 
the Agency explained that doing so would have raised significant 
practical implementation concerns. This is because MACT standards are 
generally self-implemented by facilities to a large degree whereas DRE 
testing has historically involved a detailed and iterative process 
between a facility and the regulatory agency.
    The Agency received comments that raised other concerns, including: 
(1) Whether it is necessary for a source to actually perform a DRE test 
to ensure that it is achieving DRE; 60 and (2) how can the 
Agency ensure that RCRA DRE testing is coordinated with MACT 
performance testing.
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    \60\  The statutory minimum technology requirement for 
incinerators (see RCRA 3004(o)(B)) requires the ``attainment'' of 
99.99 percent destruction and removal efficiency. DRE testing could 
be replaced by an alternative that is equally or more stringent 
(e.g., compliance with stringent limits on CO or HC) to ensure 
attainment of 99.99 percent DRE.
---------------------------------------------------------------------------

    The Agency has reconsidered DRE testing issues and is today 
requesting comment on options for ensuring compliance with a DRE 
standard, and how to coordinate DRE testing with MACT performance 
testing.
A. Options for Ensuring Compliance with a DRE Standard
    The Agency has investigated whether compliance with the CO or HC 
MACT standards would ensure that a source is achieving 99.99% DRE 
61. The vast preponderance of the data indicate that when a 
source is achieving CO levels under 100 ppmv or HC levels under 10 
ppmv, it is virtually always also achieving 99.99% DRE.62 
The Agency's investigation noted, however, an atypical, failure mode 
for the CO/HC versus DRE relationship: when low organic content waste 
is fed into a region of a combustor other than the flame zone (e.g., 
into an unfired afterburner). One test condition of the approximately 
455 investigated failed the CO/HC versus DRE relationship for this 
reason. This was a highly unusual test condition, and does not 
represent good combustion practice. CO levels were likely low because 
flame combustion was not occurring, and HC was likely low because the 
waste could have had only trace levels of toxic organics that did not 
contribute significantly to the HC loading (but which could nonetheless 
pose a health or environmental hazard).
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    \61\  The Agency evaluated approximately 455 DRE test 
conditions, where CO was less than 100 ppmv and 273 test conditions 
where HC was less than 12 ppmv, to determine if compliance with 
stringent CO and HC limits would ensure that 99.99% DRE was being 
achieved. Ten sources failed DRE even though CO or HC levels were 
below 100 ppmv or 12 ppmv (on a run average basis), respectively. 
Nine of the failures could be explained by: (1) Selecting principal 
organic hazardous constituents (POHCs) that were also common 
products of incomplete combustion; (2) feeding low concentrations of 
POHCs (a phenomenon of DRE testing is that it is very difficult to 
measure 99.99% DRE when POHCs are fed at low concentrations, even 
though emission concentrations may be trivial); or (3) feeding 
aqueous waste with such low concentrations of organics that, even 
under poor combustion conditions, the waste did not generate high 
levels of CO or HC. See USEPA, ``Draft Technical Support Document 
for HWC MACT Standards (NODA), Volume II: Evaluation of CO/HC and 
DRE Database'', April 1997.
    \62\  It could be argued that this is due to two factors: (1) 
during successful DRE testing many sources operated at CO or HC 
levels that were well below the 100/10 levels; and (2) it is not 
clear that those sources would continue to achieve 99.99% DRE at 
higher CO or HC levels (but not exceeding the 100/10 levels). This 
is unlikely to be a major concern, however, because combustion 
devices operating at CO levels under 100 ppmv are generally 
considered to be operating under good combustion conditions that 
would ensure 99.99% DRE in any event.
---------------------------------------------------------------------------

    Given the general relationship between CO, HC, and DRE and the 
highly unusual nature of the lone exception, the Agency is considering 
whether DRE testing is warranted in all cases for sources complying 
with the MACT CO and HC standards. The DRE test is a complicated, 
expensive test. In addition, although it can help indirectly to ensure 
that a source is operating under good combustion conditions, it may not 
provide the operationally direct level of assurance of good combustion 
conditions that CO or HC does. The data show that sources can be 
achieving 99.99% DRE even though CO or HC levels exceed values 
considered to represent good combustion (i.e., CO of 100 ppmv, HRA, and 
HC of 10 ppmv, HRA).63
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    \63\ Under an option the Agency is considering for establishing 
MACT standards for CO and HC, a source would be able to elect 
whether to comply with either the CO or HC standard. Although CO is 
not a direct measure of HC emissions, the Agency is considering 
requiring sources that elect to comply with the CO standard to 
document that their HC emissions also meet the standard.
---------------------------------------------------------------------------

    Accordingly, the Agency is considering three options for reducing 
the DRE testing burden, as discussed below.64 Under all 
options where DRE testing would be waived, a source would have to be in 
compliance with the final MACT standards for CO/HC, which will be 
sufficient to show ensure compliance with the DRE standard as 
well.65
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    \64\ The Agency's analysis to date has focused on the 99.99% DRE 
standard. We have not investigated whether sources that burn 
``dioxin-listed waste'' under Sec. 264.343(a)(2) and are required to 
demonstrate 99.9999% DRE are likely to achieve that DRE when 
operating under stringent CO and HC levels. Given that there are few 
HWCs that are permitted to manage such wastes and given the high 
toxicity potential of such wastes, the Agency is inclined to 
continue to require DRE testing at facilities handling those wastes.
    \65\  Long cement kilns generally cannot meet the stringent CO 
and HC limits applicable for waste combustion (i.e., 100/10 ppmv) 
because of organics in raw materials. Thus, the Agency proposed that 
such kilns comply with a CO level of 100 ppmv or a HC level of 20 
ppmv. Notwithstanding the inability to document good combustion 
conditions by complying with stringent CO/HC limits, the Agency 
believes that cement kilns that fire hazardous waste into the 
clinker end of the kiln will virtually always achieve 99.99% DRE 
because, to make marketable products, clinker temperatures must be 
approximately 2700 deg. F, and combustion gas temperatures are 
typically several hundred degrees hotter than the solids 
temperature. These temperatures are theoretically high enough to 
ensure destruction of organic compounds in the waste. Consequently, 
such kilns should not be precluded from the waivers discussed in the 
text. If such a kiln were to inject hazardous waste at nonflame zone 
locations such as mid-kiln or at the raw material end of the kiln, 
however, we are concerned that DRE may not always be achieved. The 
kiln would not be eligible for the DRE waiver.

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[[Page 24241]]

B. DRE As a MACT Versus RCRA Standard
    In investigating approaches to ensure coordination of DRE testing 
with MACT performance testing, the Agency has reconsidered whether the 
DRE standard could be effectively implemented as a MACT standard (to 
help control organic HAPs). To ensure coordination of DRE and MACT 
performance testing, the Agency is considering extending the test plan 
review period from the proposed 60 day period (see proposed 
Sec. 63.1208(e) and Sec. 63.7(b)(1)) to one year to allow regulatory 
officials time to consider DRE testing in context with MACT testing. 
With this opportunity for coordinating the testing, the Agency's 
concerns expressed at proposal about the difficulty of implementing the 
DRE standard under the self-implementing regime of MACT may be largely 
overcome (i.e., if the Agency incorporates into the MACT standards 
opportunity to review and approve the DRE test protocol). Thus, the 
Agency is considering incorporating the DRE standard as a MACT 
standard.
    Sources wishing to perform a combined DRE and comprehensive 
performance test would have to submit the test plan one year in advance 
of the test. If the review requires more than one year, the Agency can 
extend the testing date for coordination purposes (assuming the source 
has made a good faith effort to cooperate with regulatory officials to 
identify an appropriate test protocol). However, there would be no 
extensions granted for the initial comprehensive performance test 
because it is imperative that sources document compliance with the MACT 
emission standards (including those for the high priority HAPs, D/F, 
Hg) on schedule. Sources wishing to perform a combined initial 
comprehensive performance and DRE test would therefore have to be 
diligent in working with regulatory officials to ensure that the 
combined test protocol is developed and approved in a timely 
manner.66
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    \66\  The Agency also considered requiring sources to submit 
draft test protocols one year prior to the test date, regardless if 
the comprehensive performance test is to be combined with a DRE 
demonstration. We determined that may not be appropriate, however, 
because normal comprehensive performance tests should not require a 
review process longer than provided by the CAA-MACT general 
requirement. Therefore, the one-year test review period would only 
apply for those sources that wish to coordinate the comprehensive 
performance (or confirmatory) test with a DRE test.
---------------------------------------------------------------------------

    The Agency invites comment on these issues, including whether DRE 
should be incorporated as a MACT standard, and irrespective of that 
decision, whether a one-year review period provides adequate 
opportunity to review a combined DRE test and comprehensive performance 
test protocol.

IV. Notification and Reporting Requirement Considerations

A. Public and Regulatory Notification of Intent to Comply
    In the proposed rule, the Agency requested comment on strategies to 
encourage or require affected sources to comply with the final 
emissions standards at the earliest possible date. The Agency also 
asked for views on methods that could be used to determine when a 
source could realistically conclude whether it will comply in a timely 
fashion with the final standards (61 FR at 17416). A number of 
commenters argued for the Agency to require a submission from affected 
sources that identifies whether and how the facility intends to comply 
with the final standards. This notification requirement was referred to 
as a ``Notification of Intent to Comply.'' The purpose of the 
submission would be to identify the sources that will not comply with 
the final standards so that those sources could be forced to terminate 
waste burning activities as soon as possible following the effective 
date of the final HWC rule.
    Other commenters, responding to our request for comment regarding 
the proposed permit modification options (61 FR at 17455), suggested 
that all facilities be required to submit a plan that outlines the 
procedures each facility intends to follow to comply with the final 
standards. However, the purpose of this submission would be to begin an 
early process of communication between the public and the facility 
through the public disclosure of the facility's compliance strategy.
    The Agency has reviewed these comments and supports the goals and 
purposes of a requirement that compels sources to identify their 
intentions to comply with the final rule, and to describe how they will 
achieve that compliance. Furthermore, the Agency supports any process 
that promotes public notification and interaction with respect to a 
hazardous waste combustor's future operations. To the extent that some 
limitations on public participation would be the result of a 
streamlined permit modification process that may be finalized ahead of 
the HWC MACT rule, promotion of early public notification and 
intervention in this part of the rule is appropriate and desirable 
given our general policies in that regard (see, e.g., RCRA Expanded 
Public Participation Rule, 60 FR 63417 (Dec. 12, 1995)). Therefore, the 
Agency is considering a notification requirement, based on and growing 
out of ideas that were presented in comments, that may be applied to 
sources affected by the final rule. This notification requirement, 
called the Public and Regulatory Notification of Intent to Comply 
(PRNIC), would involve the facility submission and public disclosure of 
a plan that relates to whether and how the facility intends to come 
into compliance with the final standards.
    However, due to enforcement and implementation issues, the Agency 
is concerned that it is not feasible to use a submission that 
identifies only a facility's future ``intentions'' as the legal basis 
to force a facility to terminate waste burning activities before the 
statutorily based compliance period of three years. Moreover, any 
official review and approval of such submissions could conceivably slow 
down the rate at which facilities come into compliance with the final 
standards. This would thwart the objectives of a streamlined permit and 
compliance process.
    The Agency believes that the most effective application of such a 
submission is to promote public awareness, as well as discussion 
between a facility and its community, which will afford them an 
opportunity to engage in discussions regarding the details of the 
facility's plans to comply with the final standards. However, the 
Agency does not intend for this submission to undergo a formal review 
by the regulatory agencies involved.
    The Agency requests comment on this option which requires sources 
to prepare and submit for public comment a notification identifying the 
source's intentions to comply with the final rule as well as the 
strategy they intend to follow to assure compliance by the compliance 
date. This notification requirement would apply to all sources

[[Page 24242]]

burning waste on the effective date of the final HWC rule, and would 
require sources to prepare a draft notification, announce the 
availability of the draft notification as well as a future informal 
public meeting to discuss the draft notification, hold an informal 
public meeting, submit the final notification to all appropriate 
regulatory agencies, and update the notification as necessary.
    The Agency intends for the information contained in the draft 
notification to provide enough detail so that the public can engage in 
a meaningful review of the facility's compliance strategy. For example, 
if in the draft notification a facility identifies and describes the 
type(s) of control technique(s) being considered, the facility should 
include, as appropriate, waste minimization and/or pollution control 
options that may have been evaluated.
    EPA also requests comment on a requirement for affected sources to 
hold at least one informal meeting with the public before submitting 
the final notification to the appropriate regulatory agencies. The goal 
of this informal meeting is to provide a forum to facilitate dialogue 
between the affected source and its community. The meeting should 
provide an open, flexible and informal occasion for the facility and 
the public to discuss various aspects of the facility's compliance 
strategy because it provides the public direct input to the facility 
owners/operators. In addition, the meeting affords facility owner/
operators the opportunity to gain an understanding of the public's 
expectations, which can then be addressed and included in the 
facility's final submission. The Agency anticipates that the facility 
and the public will share ideas, educate each other, and continue to 
establish a framework for sound communication. However, as suggested in 
comments received from CKRC,67 the Agency understands that 
the early timing of the meeting may affect a facility's ability to have 
complete or fully accurate information, but the Agency believes that 
the benefits of early public involvement and access to information 
outweigh the drawbacks of incomplete information. Furthermore, the time 
period between the effective date of the HWC rule and the informal 
meeting announcement should provide a facility sufficient time to 
collect, analyze, select, and plan a compliance strategy. However, 
comments are invited on other appropriate time periods between the 
public notification and the informal public meeting, and on the time 
period necessary to collect the information required for the PRNIC.
---------------------------------------------------------------------------

    \67\ Memorandum, from Craig Campbell (CKRC) to Matthew Hale Jr. 
(EPA), regarding compliance plans under the HWC MACT Rule, dated 
March 18, 1997.
---------------------------------------------------------------------------

    Another timing issue relates to when a facility should notify the 
community regarding the availability of the draft PRNIC. At this stage, 
the Agency is considering to require that the notification be made on 
or before 210 days following the effective date of the final HWC rule. 
This would necessitate that an announcement of the informal public 
meeting and the availability of the draft PRNIC be made 30 days prior 
to the meeting in a manner that is likely to reach all affected members 
of the community. The Agency is considering that this announcement, of 
the informal public meeting and draft PRNIC availability, should be 
required in three ways: As a display advertisement in a newspaper of 
general circulation; as a clearly marked sign on the facility property; 
and as a radio broadcast. Each of these notices would have to include 
the date, time and location of the meeting, a brief description of the 
purpose, a brief description of the facility, a statement asking people 
who need special access to notify the facility in advance, and a 
statement describing how the draft PRNIC can be obtained. The Agency 
requests comment on this approach that requires facilities to hold an 
informal public meeting prior to the submission of the final PRNIC to 
the regulatory authorities.
    An additional requirement of the notification approach being 
considered involves the submission, to the appropriate regulatory 
agencies, of the final PRNIC 270 days following the effective date of 
the final HWC rule. The submission would contain the following 
information: The name and location of the owner operator; the location 
of the source; a statement as to whether the source is a major or area 
source; a description of any waste minimization and pollution control 
technique(s) considered; a description of the emission monitoring 
technique(s) considered; a description of the waste minimization and 
pollution control technique(s) effectiveness; a description of the 
evaluation process used to select the waste minimization and/or 
pollution control technique(s); and an outline of the key dates in the 
process that the facility plans to follow to implement the selected 
waste minimization and/or pollution control technique(s). This 
submittal should also capture the major comments or ideas that were 
discussed in the public meeting or that were submitted in response to 
the release of the draft PRNIC.
    The final requirement of the notification approach being considered 
involves updates to the final PRNIC following a significant change in 
the facility's implementation strategy. A significant change would be 
analogous to a change that would trigger a RCRA class two or class 
three permit modification request, and would apply only to changes that 
depart from the strategy described in the final PRNIC. Examples of some 
changes that may be considered significant changes are as follows: A 
change in the pollution control technique to be implemented; a request 
for permit modification; a request for an extension of the compliance 
date; or a decision to stop or to continue burning waste that is 
contrary to the final PRNIC. Additionally, all sources could be 
required to notify the public via a mailing to the facility's mailing 
list within 30 days following a determination that a significant change 
has occurred in the facility's implementation strategy. The change 
would have to be described in writing and made available to requesting 
parties via placement in an information repository or through direct 
transmittal. This requirement would be in keeping with the spirit of 
the PRNIC, which is to keep the public informed of any significant 
changes in the facility's compliance and implementation plan.
    The Agency invites comment on this submittal and the submittal 
process, and requests information on the benefits and burden associated 
with such a process. The Agency specifically invites comment on the use 
of permit modification criteria to identify a significant change that 
would necessitate an update to the PRNIC.
B. Data Compression Allowances
    The Agency is considering allowing the use of data compression 
techniques in the recording of continuously monitored parameters under 
this rule. This is in response to comments on the proposed rule 
regarding the additional burden associated with the proposed monitoring 
and recording requirements and specific requests to allow data 
compression. We are also considering revisions to parts 264, 265 and 
266 that would be conforming revisions to ensure that the RCRA rules 
are consistent with similar provisions of the proposed part 63 rules.
    Commenters raised the issue of an additional burden by the proposed 
monitoring and recording requirements. We do not agree that the 
proposed requirements pose significant additional record keeping 
burdens from current regulations (i.e., BIF rule) or existing

[[Page 24243]]

permit requirements under RCRA. However, we are interested in reducing 
the information burden--for example, how much is recorded if the data 
is automatically evaluated under an established set of specifications, 
while maintaining the integrity of the data for compliance evaluation 
purposes.
    Briefly, data compression is the process by which a facility 
automatically evaluates whether a specific data point needs to be 
recorded. Data compression does not represent a change in the 
continuous monitoring requirement proposed in rule. One-minute averages 
will continue to be generated. However, with data compression, each 
one-minute average will be automatically compared with a set of 
specifications to decide the need for recording. New data is recorded 
when the one-minute average value falls outside the set of 
specifications.
    This option should provide a good opportunity to the regulating 
agencies to focus their review of operating data, because facilities 
using data compression will record data that is indicative of non-
steady state operations more frequently than steady state operations. 
This will significantly reduce, up to 90%, the data subject to review 
by the regulating agency as the facilities' self-evaluate, under a 
previously approved set of specifications, the data being recorded.
    The dynamics of monitored parameters are not uniform across the 
regulated universe, and establishing national specifications for data 
compression techniques in this rule may not be feasible. Different data 
compression techniques can be successfully implemented for a monitored 
parameter to obtain compressed data that reflect the performance on a 
facility specific basis. As a result the Agency is considering allowing 
the sources to request the regulatory agency to use data compression 
techniques that reflect site-specific conditions of the monitored 
parameters and establish data compression specifications accordingly. 
Upon approval, sources may start data compression techniques based on 
the approved set of specification.
    At a minimum, a source implementing data compression will be 
required to record a value once every ten minutes. In combination with 
the appropriate set of specifications, a recorded value every ten 
minutes will result in a potential data recording reduction up to 90%.
    As a guideline, for the regulating agencies and sources EPA has 
developed a table to use as a guideline developing site-specific 
specification for data compression techniques. These are the basis for 
the specification in the table:
    1. Data compression limit. The closest level to a permit limit/
standard at which reduced recording is allowed. Within this level, 
minute-by-minute data recording is required. The data compression limit 
should reflect a level at which the specific parameter is unlikely to 
exceed its permit limit within a one-minute change. The other 
consideration is to set a data compression limit at which owners and 
operators can practically implement data compression.
    2. Fluctuation limits. The permissible deviation of new data value 
from previously generated value. This parameter is a reflection of 
tolerance of the agency to allow a parameter to change without 
requiring the data point to be recorded. The considerations to 
establish the fluctuation limits are (1) The potential of the regulated 
parameter to change in one minute and cause an exceedance of the permit 
limit on a rolling average basis and; (2) the maximum variation 
tolerated from a change of other related operating parameters (i.e., 
fuel and temperature, gas flow and APCD parameters).
    We invite comment on allowing data compression under this rule, 
including revising parts 264, 265 and 266, and on the following table:

         Fluctuation and Data Compression Limits Expressed as Percentages of the Permit/Standard Limits         
----------------------------------------------------------------------------------------------------------------
                                                           Fluctuation limit plus-                              
              Device                      Parameter                 minus              Data compression limit   
----------------------------------------------------------------------------------------------------------------
CEMS..............................  Particulate matter...  10%...................  60%.                         
CEMS..............................  Carbon monoxide 1      10 ppm................  50 ppm.                      
                                     hour.                                                                      
CEMS..............................  Total hydrocarbon....  2 ppm.................  60%.                         
CEMS..............................  Total mercury 10 hour  10%...................  60%.                         
CEMS..............................  Multi-metal 10 hour..  10%...................  60%.                         
                                    HCl..................  10%...................  60%.                         
                                    Chlorine.............  10%...................  60%.                         
                                    Max inlet temperature  10 deg. F.............  Limit -30 deg. F.            
                                     to dry PM APCD.                                                            
Activated carbon injection........  Min carbon injection   5%....................  Limit +20%.                  
                                     feedrate (carbon                                                           
                                     feed through                                                               
                                     injector).                                                                 
                                    Min carrier fluid      20%...................  Limit +25%.                  
                                     flowrate or nozzle                                                         
                                     pressure drop.                                                             
Dioxin inhibitor..................  Min inhibitor          10%...................  60%.                         
                                     feedrate.                                                                  
Catalytic oxidizer................  Min flue gas           20 deg. F.............  Limit +40 deg. F.            
                                     temperature at                                                             
                                     entrance.                                                                  
                                    Max flue gas           20 deg. F.............  Limit -40 deg. F.            
                                     temperature at                                                             
                                     entrance.                                                                  
                                    Maximum waste          10%...................  60%.                         
                                     feedrate.                                                                  
                                    Min combustion         20 deg. F.............  Limit +50 deg. F.            
                                     chamber temperature                                                        
                                     (exit of each                                                              
                                     chamber).                                                                  
Good combustion and APCD            Maximum flue gas       10%...................  60%.                         
 efficiency.                         flowrate or                                                                
                                     production rate.                                                           
Feed control......................  Maximum total metals   10%...................  60%.                         
                                     feedrate (all                                                              
                                     streams).                                                                  
                                    Maximum pumpable                                                            
                                     liquid metals                                                              
                                     feedrate.                                                                  
                                    Maximum total ash      10%...................  60%.                         
                                     feedrate (all                                                              
                                     streams).                                                                  
                                    Maximum total          10%...................  60%.                         
                                     chlorine feedrate                                                          
                                     (all streams).                                                             
Wet scrubber......................  Minimum pressure drop  0.5'' water...........  Limit +2''.                  
                                     across scrubber.                                                           
                                    Min liquid feed press  20%...................  Limit +25%.                  
                                    Minimum liquid pH....  0.5 pH unit...........  Limit + 1 pH unit.           
                                    Min blowdown (liquid   5%....................  Limit +20%.                  
                                     flowrate) or max                                                           
                                     solid content in                                                           
                                     liquid.                                                                    
                                    Minimum liquid flow    10%...................  Limit +30%.                  
                                     to gas flow ratio.                                                         
Ionizing wet scrubber.............  Minimum pressure drop  0.5'' water...........  Limit +2'' water.            
                                     across scrubber.                                                           
                                    Minimum liquid feed    20%...................  Limit +25%.                  
                                     pressure.                                                                  
                                    Min blowdown (liquid   5%....................  Limit +20%.                  
                                     flowrate) or max                                                           
                                     solid content in                                                           
                                     liquid.                                                                    
                                    Minimum liquid flow    10%...................  Limit +30%.                  
                                     to gas flow ratio.                                                         
                                    Min power input (kVA:  5%....................  Limit +20%.                  
                                     current and voltage).                                                      
Dry scrubber......................  Min sorbent feedrate.  10%...................  Limit +30%.                  

[[Page 24244]]

                                                                                                                
                                    Minimum carrier fluid  10%...................  Limit +30%.                  
                                     flowrate or nozzle                                                         
                                     pressure drop.                                                             
Fabric filter.....................  Minimum pressure drop  1'' water.............  Limit +2'' water.            
                                     across device.                                                             
ESP...............................  Min power input (kVA:  5%....................  Limit +20%.                  
                                     current and voltage).                                                      
----------------------------------------------------------------------------------------------------------------

V. Waste Minimization and Pollution Prevention

A. Overview
    Amendments to RCRA in 1984, and the Pollution Prevention Act of 
1990 establish a clear national policy preference for pollution 
prevention and environmentally sound recycling as the nation's top 
priority environmental management methods, over treatment, storage and 
disposal. Pollution prevention, also referred to as source reduction, 
includes any practice that reduces the amount of pollutants entering a 
waste stream, prior to recycling, treatment or disposal. Waste 
minimization, a term particular to RCRA and EPA's hazardous waste 
program, includes pollution prevention (or source reduction) and 
environmentally sound recycling. Combustion for treatment or 
destruction is a form of treatment, and is not included in the 
definitions of pollution prevention, source reduction, waste 
minimization and/or environmentally sound recycling.
    Based on previous studies, stringent limits on pollution control 
devices generally provide a strong incentive for companies to pursue 
less costly waste minimization measures to achieve compliance. The 
implementation of the Land Disposal Restrictions program has shown this 
to be the case in the RCRA program. Waste minimization measures can, in 
many cases, provide companies with a variety of benefits, including: 
improvements in production yields, reduced worker exposure, reduced 
waste volumes, reduced waste management costs, reduced liability, and 
reduced compliance burdens. As a result, many companies, including 
those affected by today's rulemaking, have made significant progress 
identifying and installing waste minimization measures that result in 
one or more of these benefits. In addition, hazardous waste generators 
that transport waste off-site for treatment, storage or disposal are 
required to certify on each hazardous waste manifest that they have a 
waste minimization program in place. In addition, facilities that have 
a RCRA permit to treat, store or dispose of hazardous wastes are 
required to certify annually that they have a waste minimization 
program in place (See sections 3002(b) and 3005(h) of RCRA).
    Past studies indicate that existing regulations can also contain 
inherent barriers that prevent companies from identifying and 
installing additional waste minimization measures that could be cost 
effective and provide an alternative or supplemental means to achieve 
compliance. Potential regulatory impediments can include: Tight 
compliance deadlines that preclude taking extra time to explore waste 
minimization alternatives, perceptions that end-of-pipe technology is 
preferred by government agencies over less well known waste 
minimization measures to achieve compliance, a tendency to continue 
relying on pollution control technology once a company has sunk 
available capital into end-of-pipe controls, and a lack of government 
willingness to explore more flexible compliance approaches.
    During extensive interaction with public stakeholders during the 
development of EPA's Hazardous Waste Minimization National Plan 
(released in 1994), some companies emphasized that short compliance 
deadlines after the promulgation of end-of-pipe standards are a 
significant impediment to fully identifying and installing waste 
minimization measures that could either replace or supplement end-of-
pipe pollution control measures that may still be necessary. As a 
result, companies are likely to opt for installing ``end-of-pipe'' 
pollution controls to meet compliance deadlines, instead of pursuing 
waste minimization and pollution control measures as a compliance 
approach. At large complex manufacturing facilities (such as chemical 
manufacturing plants), short compliance deadlines are a particular 
barrier since completing a waste minimization options assessment 
requires consideration of chemical reaction redesign, testing and 
installation. In contrast end-of-pipe controls can often be installed 
more quickly than waste minimization process changes, even though they 
may be more expensive. In addition, once capital has been sunk into 
end-of-pipe pollution controls, there is little incentive for companies 
to then spend money exploring pollution prevention/waste minimization 
options that would offset the need for the end-of-pipe controls. This 
factor is one of the major factors to consider in today's rulemaking. 
This is discussed in more detail below.
B. EPA Proposed Flexible Waste Minimization Incentives
    EPA was aware, in its April 1996 proposal for this rulemaking, that 
promulgating MACT standards may contain some inherent barriers to 
identifying and installing waste minimization technologies that could 
be more cost effective for meeting environmental protection standards 
(in some cases) than end-of-pipe air pollution control equipment alone. 
Consequently, EPA requested comment on three regulatory incentives that 
could partially offset potential barriers and provide regulated 
companies with an increased opportunity to identify and install waste 
minimization technologies that reduce or eliminate hazardous waste 
entering combustion feed streams as a cost effective approach to 
compliance. EPA's objective in this effort is to promote flexibility in 
the use of waste minimization measures that would reduce the amount 
and/or toxicity of hazardous wastes entering combustion feed streams, 
either as an alternative to end-of-pipe combustion measures, or in 
combination with combustion measures, to meet MACT standards.
    EPA requested comment on two approaches that use waste minimization 
facility planning to identify cost effective waste minimization 
measures that reduce hazardous wastes entering combustion feed streams. 
Waste minimization planning has been used in over 20 states as a method 
to encourage companies, particularly those that generate and manage 
wastes on site, to identify cost effective waste minimization measures 
that can be used in place of, or in combination with, end-of-pipe 
pollution control measures. Of the 21 commercial incinerators and the 
141 on-site hazardous waste incinerators facilities known to be covered 
by today's rule, 43-44 percent

[[Page 24245]]

of the facilities are in states that have mandatory waste minimization 
planning programs; 14 percent are in states that have voluntary waste 
minimization planning programs; and 42-43 percent are in states that do 
not have formal waste minimization planning programs.
    The first waste minimization facility planning approach proposed 
for comment sought to encourage facilities to reduce the amount of 
hazardous waste entering combustion feed streams as much as possible 
through cost effective waste minimization measures. The proposal sought 
to accomplish this objective by requiring all facilities covered by 
this rulemaking to provide to the appropriate EPA or State permitting 
authority adequate information on waste minimization measures that 
would reduce hazardous wastes entering combustion feed streams. 
Requiring facilities to formally consider cost effective waste 
minimization options would raise the likelihood that hazardous waste 
generation could most cost effectively be reduced at the source or 
recycled, as a preferred approach to combustion. Since many of these 
facilities are located in states that have mandatory or voluntary waste 
minimization planning programs, EPA hoped to build on a process already 
in place. States that have mandatory waste minimization planning 
programs generally require facilities to provide a description of 
changes in process equipment, raw materials, materials handling, 
recycling, maintenance or other changes that would reduce the amount 
and/or toxicity of wastes that are treated or disposed. None of the 
existing mandatory or voluntary State waste minimization planning 
programs specifically address reductions of combusted hazardous as an 
objective of the planning process. EPA requested comments on this 
approach to determine if the approach could provide greater flexibility 
for facilities to build on requirements of existing state programs to 
achieve compliance with MACT standards.
    In the second waste minimization planning option, EPA proposed to 
provide EPA Regions and States with the discretionary authority to make 
case by case determinations regarding which facilities would be 
required to provide information on waste minimization alternatives to 
reduce hazardous wastes entering combustion feed streams. This 
determination could take into account several factors, including, for 
example, whether an existing state program had already accomplished the 
equivalent of this objective, the extent to which this requirement may 
be too burdensome for some states, and the extent to which facility 
specific conditions indicate emissions could be best controlled by feed 
stream management and waste minimization at the source.
    The third waste minimization incentive EPA proposed for comment 
allows facilities to apply for up to a one year extension to the three 
year compliance period allowed under the CAA and 40 CFR 
63.6(i)(4)(i)(A) in cases where facilities need additional time to 
identify and install waste minimization measures that would reduce 
hazardous wastes entering combustion feed streams as a method (either 
alone or in combination with combustion or other treatment technology) 
to achieve compliance. 40 CFR 63.6(i)(6)(i) describes the requirements 
for requesting a compliance extension. A request must include a 
description of the pollution control, process changes or process 
equipment to be installed, a compliance schedule that describes the 
dates by which these controls, process changes and process equipment 
will be initiated, the dates by which installation will be completed, 
and the date by which compliance will be achieved. The Administrator or 
a State that has an approved Part 70 permit program or has been 
delegated the authority to implement and enforce the emission standard 
for that source may grant such extensions. This incentive would, at 
least in part, offset some of the time barriers large companies might 
need to fully explore and install waste minimization options in 
addition to any combustion equipment that may still be necessary.
C. Comments Received
    EPA received comments on waste minimization from 22 commenters. 
Companies that operate on-site units (many of which are large chemical 
plants) commented that, while waste minimization can provide a cost 
effective approach to compliance, neither the three year compliance 
period allowed for this rule, nor the three years plus a one year 
extension is sufficient time to complete the two track task of 
designing, testing and installing waste minimization process changes 
that reduce hazardous wastes entering combustion feed streams, and 
designing and installing any combustion or other treatment equipment 
that may nevertheless be necessary. Waste minimization is an on-going 
process that should be continually under investigation in all 
companies. However, EPA agrees that in cases where standards are 
promulgated that change the economics of how much pollution can be 
emitted to the environment, even on-going waste minimization programs 
may not be able to anticipate the best combination of waste 
minimization and treatment measures to achieve compliance. EPA agrees 
that in some cases, particularly at large complex manufacturing 
operations, the three year compliance period may not be sufficient time 
to consider waste minimization measures, and in other cases, three 
years plus a one year extension may not provide sufficient time.
    Commercial facilities continue to assert that they have few direct 
opportunities to pursue waste minimization since they have little 
control over the wastes generated by their customers. Some commercial 
companies believe EPA should implement ``good actor'' incentives for 
companies that educate their customers regarding available waste 
minimization resources. Such incentives could include reduced 
inspection frequencies, reduced performance testing, and a recognition 
program. EPA agrees that commercial combustors of hazardous waste have 
little direct control over the wastes generated by their customers and 
therefore will experience little if any flexibility from any the waste 
minimization incentives proposed for comment. The comment to implement 
good actor incentives as an incentive for commercial companies to 
educate their customers on waste minimization did not contain 
sufficient information to determine the merits of such an approach. EPA 
does point out, however, that this type of concept, i.e., one in which 
private industry proposes an improvement in environmental performance 
through and innovative regulatory approach, is the type of approach 
that might be appropriate for further exploration at a later time.
    Three states commented. Two states believe EPA should encourage 
waste minimization in this rulemaking. However, they believe three 
years plus a one year extension may not be enough time for companies to 
identify and install waste minimization measures. The third state said 
that waste minimization incentives should not be necessary in this rule 
because companies have had many years to pursue waste minimization 
programs and should have already considered waste minimization as an 
approach to compliance. EPA agrees with the two states that, in some 
cases, three years plus a one year extension may not be sufficient time 
to identify and install waste minimization measures that achieve 
compliance. EPA agrees with the third state to a limited extent, in 
that companies have had many years to

[[Page 24246]]

implement waste minimization programs, and notes that most, if not all, 
of the companies affected by today's rulemaking probably have waste 
minimization programs in place. However, as noted earlier, waste 
minimization is an on-going process, and the stringent requirements of 
the MACT standards for hazardous waste burning facilities may shift the 
economics for particular companies in a way that makes certain waste 
minimization measures more cost effective than they otherwise would 
have been, and companies may need additional time to design and install 
these approaches.
    EPA's Interim Final Guidance to Hazardous Waste Generators on the 
Elements of a Waste Minimization Program in Place (May 28,1993) 
recognizes companies make these determinations on a case by case basis. 
EPA's guidance describes six general program elements that contribute 
to successful corporate waste minimization programs. These elements 
include: (1) Top management support that emphasizes waste minimization 
in its corporate policy, employee involvement and rewards for ideas 
that reduce waste generation, setting goals for waste reduction, and 
other proactive management steps; (2) characterization of waste 
generation and waste management costs, identification of sources of 
waste in the production process, how they were generated, the value of 
raw materials and lost products that are escaping as waste, and the 
cost of replacing and managing wasted materials; (3) periodic waste 
minimization assessments that are tied into other efforts to improve 
environmental management; (4) a cost allocation system that assigns the 
true cost of generating and managing wastes to the activities that 
generate the waste in the first place; (5) encourage technology 
transfer that shares ideas and technology between parts of the 
organization and with other organizations where appropriate; and (6) 
program implementation and evaluation that evaluates successes and 
failures, and shares information with the public. While these 
principles were published in regard to RCRA's waste minimization 
certification requirement, the principles can be used as relevant 
guiding principles by companies who wish to consider using waste 
minimization measures as a method to reduce hazardous wastes entering 
combustion feed streams regulated under MACT standards and the Clean 
Air Act.
    One company argues in its comments that mandatory waste 
minimization planning should be made a MACT requirement so that 
facilities are forced to consider source reduction and recycling 
alternatives, rather than simply installing end-of-the-pipe equipment 
to control HAP emissions. The company argues that this approach would 
be particularly useful in controlling combustion feed streams to limit 
the combustion of metals and other constituents that can not be 
adequately controlled using end-of-pipe measures.
    EPA has examined this issue closely. While mandatory facility 
planning on the surface may appear to force facilities to consider 
waste minimization solutions, providing appropriate regulatory 
incentives and harnessing the power of public dialogue for companies to 
identify and install waste minimization measures will result in more 
waste minimization measures.
    Sixteen states have implemented mandatory waste minimization 
planning programs and several more have implemented voluntary waste 
minimization planning programs in an effort to encourage facilities to 
pursue waste minimization measures over end-of-pipe measures. A Federal 
mandatory and prescriptively detailed waste minimization planning 
requirement would be, at best, marginally effective in causing large 
companies (which make up the population of facilities affected by 
today's regulation) to identify and install waste minimization measures 
beyond what they would do under current requirements. Large companies 
generally already have the necessary staff, information, and resources 
to pursue waste minimization alternatives where it makes sense to do 
so. Whether large companies choose waste minimization solutions over 
end-of-pipe solutions depends on a variety of economic and other 
factors that outweigh attempts to identify additional waste 
minimization alternatives. EPA hopes to encourage minimizing 
impediments to waste minimization by soliciting comments on the 
approaches contained in today's NODA. Furthermore, the remaining States 
have chosen to not implement mandatory or voluntary waste minimization 
planning programs. Some States believe that mandatory waste 
minimization planning does not improve waste minimization results. It 
would not be appropriate for EPA to either add additional burden to 
State waste minimization programs that already exist or to States that 
have chosen not to have waste minimization planning programs.
    EPA is, instead, asking for comment on a refined approach that 
encourages facilities to consider waste minimization alternatives, uses 
public dialogue to advance waste minimization efforts, and provides 
regulatory incentives for companies to pursue waste minimization 
solutions. This approach will achieve many of the same ends more 
efficiently than a detailed and prescriptive mandatory waste 
minimization planning requirement.
D. Comments Requested on Additional Waste Minimization Incentives
    EPA is requesting comment on a three regulatory incentives that are 
intended to encourage companies to pursue waste minimization measures 
to reduce or eliminate hazardous wastes entering combustion feed 
streams.
    The first incentive was proposed in EPA's April 19, 1996 MACT 
proposal, and is being refined in today's NODA. EPA requested comments 
on granting regulated facilities the opportunity to request a one year 
extension to the three compliance period allowed under the Clean Air 
Act in cases where the additional time is clearly needed to identify 
and install waste minimization measures that would reduce the amount of 
hazardous waste combusted as a means of achieving compliance. In 
today's NODA, EPA is requesting comment on several clarifying factors 
that will promote consistency while still allowing flexibility in 
decision-making among the EPA Regions and authorized States who will 
make determinations on whether or not to grant one year extensions to 
facilities who apply.
    EPA is also requesting comment on extending the agency's current 
audit and penalty policies to allow some companies to enter into a 
written consent agreement or consent orders (CA/COs) in cases where it 
is clear that longer than four years (i.e., longer than a one year 
extension) is needed to identify and install waste minimization 
measures that significantly reduce hazardous wastes entering combustion 
feed streams. These two approaches are discussed more below.
    40 CFR 63.6(i) describes the authority, procedures and requirements 
for requesting a one year compliance extension for meeting MACT 
standards. Requests must include certain information, including: A 
description of the pollution control, process changes or process 
equipment to be installed, a compliance schedule that describes the 
dates by which these controls, process changes and process equipment, 
will be initiated, the dates by which installation will be completed, 
and the date by which compliance will be achieved. Today, EPA is 
requesting comment on language that clarifies the term ``process 
changes'' in 40 CFR 63.6(i)(6)(i)(B)

[[Page 24247]]

solely with respect to hazardous waste burning incinerators, LWAKs and 
cement kilns, to make it clear that waste minimization measures are 
included in the meaning of process changes for meeting MACT standards.
    By making this clarification, EPA hopes to encourage the use of 
waste minimization measures to reduce the amount of hazardous waste 
entering combustion feed streams as an alternative to or supplement to 
end-of-pipe emission controls. With respect to hazardous waste burning 
incinerators, LWAKs and cement kilns, EPA includes in the definition of 
``process changes'' the following activities: equipment or technology 
modifications, reformulation or redesign of products, substitution of 
raw materials, improvements in work practices, maintenance, inventory 
control, and environmentally sound recycling measures which reduce the 
amount and/or toxicity of hazardous waste entering feed streams of 
combustion devices. The term environmentally sound recycling includes 
on-site (including closed-loop recycling) and off-site recycling 
activities that use, reuse or reclaim hazardous materials in accordance 
with EPA regulations. Burning for energy recovery is not included in 
the meaning of ``process change'' as a basis for requesting a one year 
extension for waste minimization purposes. This proposed definition 
would apply only to hazardous waste burning incinerators, LWAKs and 
cement kilns.
    The Administrator or a State that has an approved part 70 permit 
program (or has been delegated the authority to implement and enforce 
the emission standard for that source) may grant extensions under 40 
CFR 63.6(i)(9). Under this approach, decisions to grant one year 
extensions will be made by EPA Regional offices and approved or 
delegated state programs. EPA recognizes that States employ a variety 
of approaches for requiring or encouraging the consideration of waste 
minimization measures in achieving compliance with regulatory 
requirements. It is not appropriate for EPA to supersede State 
approaches with a uniform set of criteria for evaluating waste 
minimization requests for one year compliance extensions. However, EPA 
believes it is appropriate to encourage (but not mandate) consistency 
in how these decisions are made. Therefore, EPA is requesting comment 
on a proposal to include four factors that must, at a minimum be 
considered by EPA Regional offices and approved or delegated state 
programs in approving or denying requests for one year compliance 
extensions for hazardous waste burning incinerators, LWAKs, and cement 
kilns). These factors include:
     The extent to which the process changes (including waste 
minimization measures) proposed as a basis for the extension reduce or 
eliminate hazardous wastes entering combustion feed streams and are 
technologically and economically feasible.
     Whether the magnitude of the reductions in hazardous 
wastes entering combustion feed streams through process changes are 
significant enough to warrant granting an extension.
     A clear demonstration that reductions of hazardous wastes 
entering combustion feed streams are not shifted as increases in 
pollutants emitted through other regulated media.
     A demonstration that the design and installation of 
process changes, which include waste minimization measures, and other 
measures that are necessary for compliance cannot otherwise be 
installed within the three year compliance period.
    These factors will provide a degree of consistency, while still 
allowing flexibility among EPA Regional offices and approved States, in 
the use of this innovative regulatory approach. EPA will also provide 
separate guidance that provides examples of how to apply the factors to 
consider and additional information that will be helpful to government 
and regulated entities. For example, the guidance will provide examples 
that will help gauge whether the magnitude of proposed requests to 
reduce hazardous wastes entering combustion feed streams through 
process changes are significant enough to warrant granting an 
extension. For example, companies that commit to a 25% or greater 
reduction in hazardous wastes entering combustion feed streams may be 
more likely to be considered for an extension than companies that 
commits to only a five percent reduction.
    EPA anticipates that the guidance will contain other examples on 
how to evaluate cases where a low percentage reduction may actually 
reflects a significant improvement relative to previous significant 
waste minimization achievements. The guidance will address how to 
evaluate shifts from combustion feed streams to other regulated media, 
such as wastewater effluents or other pollutant sources. EPA 
anticipates the guidance will address assuring that the proposed 
process changes that include waste minimization measures are critical 
path steps toward compliance, and not process improvements that have 
little to do with reductions of hazardous waste feed streams, and could 
otherwise have little impact on compliance. Waste minimization measures 
that are not on a critical path toward compliance or that do not have a 
direct impact on reducing or eliminating hazardous waste streams 
entering combustion feed streams are not good candidates for a one year 
extension. Finally, EPA anticipates the guidance will include a list of 
states that have approved part 70 permit programs, a list of states 
that operate waste minimization technical assistance programs, and a 
list of States that have mandatory or voluntary waste minimization 
planning programs.
    EPA also points out that companies that choose to apply for a one 
year extension for waste minimization purposes may wish to coordinate 
the development of compliance extension applications with the 
development of ``public regulatory notifications of intent to comply,'' 
contained in today's rule, since much of the developmental work for the 
two actions should be nearly identical.
    In the comments received, several companies and states said that, 
in some cases, even the three year compliance period plus a one year 
extension would not be adequate time to design, and install waste 
minimization measures or additional combustion or treatment measures 
necessary to ensure compliance with the MACT standards. It may be 
appropriate, under the circumstances described below, to grant 
facilities who demonstrate that longer than three years plus a one year 
extension is necessary to implement waste minimization measures that 
significantly reduce the amount and/or toxicity of hazardous waste 
entering combustion feed streams additional time (i.e., longer than 
four years). Reducing the amount of hazardous waste entering combustion 
feed streams provides greater long-term levels of protection for public 
health and the environment than other non-waste minimization/pollution 
prevention measures that could be used to comply with the MACT 
standard. Since facilities that need longer than three years or the 
three year date plus a one year extension to meet compliance are 
technically in violation (not including facilities that are granted a 
one year compliance extension and meet compliance within the one year 
extension period), EPA will require these facilities to enter into 
written consent agreements/consent orders (CA/COs) to receive this 
additional time. The process changes that include waste minimization 
measures must clearly demonstrate the facility will achieve significant 
reductions in the amount of

[[Page 24248]]

hazardous wastes entering combustion waste streams over what would have 
otherwise have been combusted over the long term using combustion-based 
compliance alternatives installed within the three year compliance 
period (or three years plus a one year compliance extension). EPA 
encourages facilities to consider undertaking longer-term waste 
minimization compliance approaches, subject to limitations proposed 
today. EPA will consider such requests using its enforcement discretion 
and the principles articulated in the Agency's ``Policy on Encouraging 
Self-Policing and Voluntary Correction'' (60 FR 66706, December 22, 
1995) (i.e., the ``Audit Policy''). Within this context, EPA may, in 
certain cases, consider a reduction of penalties for facilities that 
are able to install compliance solutions that demonstrate significant 
reductions in hazardous wastes entering combustion feed streams, but 
need additional time beyond that allowable under the regulations.
    To qualify for this special consideration for additional time, a 
regulated entity would have to submit a written request that contains 
the information listed below. Facilities must submit requests to the 
EPA Regional Office that has oversight for their facility within one 
year after the MACT standards for this rulemaking are promulgated. The 
request would include:
     An explanation of why the facility cannot reasonably 
implement their proposed process changes that include waste 
minimization measures within four years from the date of the 
promulgation of the MACT standards.
     An explanation of how the facility's proposed process 
changes (that include waste minimization measures) will achieve greater 
reductions in quantity and/or toxicity of hazardous wastes entering 
combustion feed streams. The proposed reductions must be significant. 
EPA will make these determinations on a case-by-case basis.
     An explanation of how the waste minimization/pollution 
prevention measures are necessary to achieve compliance with the MACT 
standards (i.e., waste minimization measures which reduce hazardous 
wastes entering combustion feedstreams must be shown to have a direct 
impact on the subsequent design, installation and testing of combustion 
or other treatment measures necessary to achieve and go beyond 
compliance standards), and a schedule for implementation of the 
proposal.
     A waste minimization facility plan. This plan must follow 
EPA's ``Pollution Prevention Facility Planning Guide'' (May, 1992; NTIS 
# PB92-213206), or, if the facility is located in a State that requires 
mandatory waste minimization planning, the form of waste minimization 
planning required by that State.
    Regulated entities must demonstrate a clear intent to achieve 
compliance in a timely fashion by entering into a consent agreement/
compliance order with EPA as soon as they exceed the allotted time 
provided by the regulations (including any regulatory extension). EPA 
would then exercise its enforcement discretion to treat a facility's 
failure to achieve compliance by the regulatory deadline as a violation 
that can receive penalty mitigation under the Agency's Audit Policy. 
Under the Audit Policy the Agency may give up to a 100% reduction in 
the gravity based component of potential penalties. To qualify for 
eliminating the gravity-based penalty a facility will have to show that 
it has a compliance management program that meets the criteria for due 
diligence under the Audit Policy. Otherwise, the facility may qualify 
for a 75% reduction of the gravity component of the penalty. EPA will 
provide examples of past cases in the supplemental guidance noted 
earlier in this section.
    EPA realizes that some waste minimization compliance measures may 
be more cost effective than combustion based approaches. EPA will 
retain its discretion to recover any economic benefit gained as a 
result of noncompliance. This will ensure that facilities that delay 
compliance for a specific period of time do not receive an economic 
benefit during the period of non-compliance over regulated entities 
that do comply within the regulatory deadline. For example, EPA may 
recover the economic benefit a company receives by delaying capital 
expenditures for modifying their manufacturing process to meet the new 
compliance standards. EPA may exercise its discretion in appropriate 
circumstances to choose the lower figure between: (1) the company's 
pollution prevention/waste minimization expenditures, and (2) 
expenditures the company would have incurred implementing other methods 
to come into compliance, when calculating economic benefit during the 
period of non-compliance with the new regulatory standards. EPA will 
also use its enforcement discretion to waive recovery of insignificant 
amounts of any economic benefit resulting from a facility's delayed 
compliance.
    EPA is also encouraging companies to pursue waste minimization 
measures in an expansion of the provision in the Clean Air Act 
regulations that requires facilities to submit an early notification 
that they intend to comply with the MACT standards as they become 
effective (usually about 2-3 years after the notification is 
submitted). The expansion, called a public regulatory notifications of 
intent to comply, would require facilities to include substantially 
more detail in this notification on: (1) What they have considered 
doing to meet the MACT standards (particularly with respect to waste 
minimization); and (2) how they have decided to proceed. This expanded 
notification would be sent not only to the regulatory agency, but would 
also be made available to the local community. In addition, the 
facility would be required to hold an informal meeting with the local 
citizenry to discuss the notification. However, regulatory agency 
review and approval of the notification is neither mandated nor 
expected. This approach would harness the power of public opinion to 
urge facilities to consider waste minimization alternatives to end-of-
pipe ways of meeting the MACT standards. This approach is described in 
detail elsewhere in today's NODA for public comment.
    EPA requests comment on the extent to which the proposed one year 
compliance extension, the proposed opportunity for companies to enter 
into consent agreements/consent orders for periods that extend beyond 
four years, and the PRNIC approach provide companies with appropriate 
incentives to pursue waste minimization measures to achieve compliance.

VI. Permit Requirements

A. Coordination of RCRA and CAA Permitting Processes
    In the NPRM, EPA proposed to place the final MACT standards in 40 
CFR Part 63 and reference those standards in 40 CFR Parts 264 and 266 
(61 FR at 17451). Under this proposal the standards would only be 
written out in the CAA regulations, but they would legally be part of 
both the CAA and RCRA regulations. Thus, both programs would have an 
obligation to address the standards in permits issued under their 
authority. EPA proposed this approach to provide the maximum amount of 
flexibility for state permitting authorities to coordinate the issuance 
of permits and enforcement activities in a way which most effectively 
addresses their particular situation.
    After reviewing the NPRM comments, there is some question on 
whether the proposed approach will provide the maximum amount of 
flexibility to the

[[Page 24249]]

state permitting authorities. The proposed approach would still require 
in most cases at least two different permitting authorities to review 
the air emission standards in a permit. Since under the original 
proposal the standards would be in both the RCRA and CAA regulations, 
permit writers from each program might be required to address them to 
some degree in a permit under that program, either by writing them 
directly in the permit or by referencing them from the other permit. 
The proposed approach might not have given states the flexibility to 
implement the new standards under a single regulatory program. Thus, 
the proposed approach would result in duplicative permitting actions in 
many cases.
    Commenters had several other concerns with an approach where the 
air emission standards are incorporated into two permits. One major 
problem described by commenters is that the overlapping permit 
conditions of the Title V and RCRA permits would be subject to two 
separate permit modification procedures, administrative appeals 
procedures, and potentially separate judicial procedures as well. The 
Agency now believes that this outcome could be needlessly duplicative 
and unwieldy, and therefore not consistent with the Agency's intent to 
simplify permitting.
    Additionally, commenters were concerned that the proposed approach 
would have allowed for dual enforcement scenarios where enforcement 
actions under both statutes would be brought against the facility for a 
single violation. In the NPRM, EPA stated that the Agency did not 
expect to enforce under both permits (61 FR at 17452). However, 
commenters noted that this statement did not restrain the states from 
initiating dual enforcement actions, or citizens from initiating dual 
citizen suits.
    Codifying the MACT standards in only one place in the regulations 
(unlike the proposed scheme) may actually provide states the greatest 
flexibility in the way they issue permits and prevent duplication of 
effort. Although the standards would be codified under one statute, 
states could decide which program they want implementing the standards. 
A state would be free to decide, for example, to have its RCRA staff 
implement a set of CAA standards. Another approach would be for a state 
to decide under which state statute to adopt the MACT standards based 
on which part of their program they wish to implement the standards. 
For example if EPA places the MACT standards in part 63 only (see 
below), a state could still decide to adopt those standards under their 
state solid waste statute and implement the standards through their 
RCRA hazardous waste program, depending on how their state solid waste 
statute is written. The basic premise in this approach is that it is 
not significant to EPA, nor to proper implementation of RCRA or CAA, 
under what statute a state adopts a RCRA or CAA regulation.
    EPA particularly would like to take comment on this issue. Do 
states believe they can decide under which program to implement the 
MACT standards if they are only placed in Part 63? EPA is concerned 
that states be allowed to implement the standards through either their 
CAA or their RCRA program, whichever works best for their particular 
situation.
    Currently, EPA is considering placing the MACT standards only in 40 
CFR part 63 and relying on the air program implementation scheme, 
including the Title V permitting program, to bring facilities into 
compliance with the new standards. This approach (as opposed to the 
converse--placing the standards only in the RCRA regulations) is the 
only approach that appears feasible to allow the standards to be 
codified in only one place in the regulations. The Agency would rely on 
the integration provision of RCRA section 1006(b)(1) to defer RCRA 
controls on these air emissions to the part 63 MACT standards. (The CAA 
does not have a similar integration provision which would allow 
deferral of CAA requirements to RCRA regulations.)
    We emphasize, however, that under this approach, there would still 
be a need for a RCRA permit at HWC facilities, to address any other 
RCRA units on site, and to address RCRA regulations which apply to all 
types of RCRA facilities and which are not duplicated under CAA. For 
example, a permit will be required to address hazardous waste storage 
units that hold the waste prior to combustion. As with all RCRA 
permits, the permit would require compliance with the standards in 40 
CFR part 264 (including general facility standards, preparedness and 
prevention requirements, contingency planning and emergency procedure 
requirements, manifesting requirements, recordkeeping and reporting 
requirements, releases from solid waste management units requirements, 
closure and post-closure requirements, financial requirements, 
corrective action requirements, storage requirements, materials 
handling requirements, and air emissions standards for process vents, 
equipment leaks, tanks, and containers). The omnibus provision of RCRA 
Section 3005(c)(3), codified at Sec. 270.32(b)(2), which provides for 
additional permit conditions as necessary at a particular site to 
protect human health and the environment, would also need to be 
addressed in the RCRA permit, with respect to the combustor and other 
activities at the facility. (This issue is discussed further in the 
next section.) Among other consequences, this means that the current 
program of processing RCRA HWC permits will continue until EPA 
finalizes any program changes. It remains a high priority to bring all 
HWC under full Part B permits as soon as possible.
    Although the RCRA permit would not need to duplicate the MACT 
controls contained in a Title V permit, there will typically be a 
number of waste management activities associated with the combustion 
unit that would need to be addressed in the RCRA permit (and not the 
Title V permit), such as materials handling (feed and residues) and 
combustor-specific (but not MACT-related) waste analysis requirements 
and feed restrictions. If, as under the original proposal, the Agency 
decides to retain the DRE standard in the RCRA regulations, then DRE 
would also need to be addressed in the RCRA permit.
    The discussion above describes one approach the Agency is 
considering for the final rule. If this approach were adopted, it would 
establish how EPA would implement the new MACT standards where the 
Agency has permitting jurisdiction. However, in many cases, states are 
delegated RCRA and CAA authority. It would therefore be up to the state 
program to decide how best to implement the MACT standards given the 
particular authorities of the state. The approach described today may 
be better suited to provide greater flexibility for state approaches, 
whether the State prefers to rely primarily on the MACT and Title V 
permit process or the RCRA permit process to impose the new standards.
    The Agency recognizes that in many cases facilities will already 
have a RCRA permit in place when the MACT standards become effective. 
This situation raises the question of what happens to RCRA permit 
conditions related to combustor air emissions.
    From an overall standpoint, it is expected that the MACT standards 
will be more stringent than many current RCRA regulations and permit 
conditions. However, at some individual sites, certain RCRA permit 
conditions may be more stringent than the corresponding MACT emissions 
standards. Some potential reasons why such a situation would occur are 
because the RCRA permit condition is

[[Page 24250]]

based on a site-specific risk evaluation under the BIF rule or the 
omnibus provision; because the MACT standard is in a different format 
than the permit condition (e.g., a mass emission rate or removal 
efficiency format in a RCRA permit vs. a concentration-based standard 
for HCl under MACT) and at that particular site the RCRA format yields 
more stringent control; because, in the case of CO limits in early 
incinerator permits, the RCRA permit limit was based on levels during 
the trial burn; or because the facility was one of the lower emitters 
in the standards development MACT pool.
    The Agency's overall intent is for the MACT standards to replace 
the RCRA air emissions standards for hazardous waste combustors. 
Therefore, where the Agency has permitting jurisdiction, the RCRA air 
emissions permit limits for HWCs, with the exception of site-specific 
risk-based limits, would be deleted from RCRA permits when the MACT 
standards become operational. In the case of site-specific risk-based 
limits, based either on the BIF metals and HCl/Cl2 requirements or 
omnibus authority, these limits would remain in RCRA permits to satisfy 
the protectiveness requirement of RCRA section 3004 (a) and (q). As 
with EPA issued permits, in authorized states any site-specific risk-
based limits would need to be retained where necessary to satisfy RCRA 
protectiveness requirements. Since authorized states are allowed to be 
more stringent, states will determine, in the process of deciding 
whether to delete old RCRA-based regulations and in the permitting 
process, whether to keep or delete more stringent permit conditions 
which are not based on a site-specific risk finding.
    EPA would like to take comment on the approach of placing the MACT 
standards only in the part 63 regulations, and deferring the RCRA 
standards, as described above.
B. Permit Process Issues
    As discussed above, the Agency is considering an approach of 
placing the MACT standards only in 40 CFR part 63 and using RCRA 
1006(b) authority to defer RCRA permitting to the Title V permitting 
program for the air emission standards only. This approach raises the 
issues of how and when the permitting authorities should modify 
existing RCRA permits to remove the air emission standards. The 
Agency's current thinking is that the RCRA permit should continue to 
apply until a facility completes its comprehensive performance testing 
and its Title V permit is issued (or its existing Title V permit is 
modified to include the MACT standards). The RCRA permit would then be 
modified to remove the air emission limitations which are covered in 
the Title V permit. Another option is to modify the RCRA permit at the 
time the facility submits their comprehensive performance test results. 
However, it is beneficial to wait until the test results are reviewed, 
approved, and written into a Title V permit before deleting any RCRA 
permit conditions because of the greater level of Agency and public 
review that occurs during the permit process. The Agency would like to 
take comment on this issue. At what point should the RCRA permit be 
modified to remove air emission standards? How should the switch-over 
to the new permitting system occur? Note that irrespective of when the 
Title V permit is issued/modified, the MACT standards and associated 
operating limits become enforceable according to the schedule in the 
final rule.
    After the compliance date for the final rule, but before the RCRA 
permit is modified to remove any air emission limitations, there will 
be a period where a facility will have both a RCRA permit that 
addresses air emissions and either: (1) A precertification of 
compliance document with applicable operating conditions that they have 
submitted; or (2) a Title V permit which also addresses air emissions. 
Note, the RCRA permit will continue to apply until such time that it is 
modified to remove any air emission limitations. The precertification 
of compliance document or Title V permit will not automatically 
supersede RCRA permit conditions as a matter of law. The more stringent 
conditions will govern.
C. Omnibus and RCRA/CAA Testing Coordination
    As discussed in the preamble to the proposed rule (61 FR at 17371), 
EPA currently has a national RCRA policy of strongly recommending to 
all federal and state RCRA permit writers that, under the omnibus 
provision of RCRA section 3005(c)(3), site-specific risk assessments 
(SSRAs) generally be performed as part of the RCRA permitting process 
to determine whether additional conditions are necessary to protect 
human health and the environment. The results of these risk assessments 
are then used to set protective permit conditions. Under the new 
permitting scheme that the Agency is considering (placing the MACT 
standards only in 40 CFR part 63), the Agency is considering when the 
RCRA omnibus provision would continue to be used--for example, to 
require a site-specific risk assessment--and the timing of the RCRA 
omnibus finding in relation to the Title V permit issuance/
modification.
    As discussed in the NPRM, the Agency has indicated a preference for 
modifying our current policy of recommending that a site-specific risk 
assessment (SSRA) be performed during permitting at hazardous waste 
combustors in most cases (61 FR at 17372). Depending on the scope and 
level of the final MACT standards, this policy may need to be re-
evaluated. For at least some facilities, there might still be 
sufficient cause to perform a SSRA under the RCRA omnibus permitting 
authority.
    Thus, the Agency is also considering the timing issue of whether a 
RCRA omnibus finding would be expected to occur at the same time as the 
Title V permitting decision (or the Title V permitting modification 
decision, if this is more appropriate, since some of these units will 
most likely already have Title V permits). The Agency expects that many 
of the trial burns to support SSRAs will already be completed prior to 
the effective date of the MACT rule, and would not need to be repeated 
provided none of the resulting emissions limitations are relaxed based 
on the MACT rule. For facilities where trial burns for risk assessments 
have not been performed, a RCRA omnibus determination as to whether a 
SSRA is needed can be made in most cases before the comprehensive test 
protocol is finalized. This situation would allow the MACT 
comprehensive test protocol and RCRA trial burn plan to be coordinated 
with respect to sampling and analysis procedures and operational 
protocols. However, the Agency does not plan to hold up comprehensive 
performance test approval or the Title V permit process (modified or 
new permits) to accommodate a RCRA omnibus finding.
    If it were not possible to make the RCRA omnibus determination in 
sufficient time to allow coordinated emissions testing, then a separate 
RCRA trial burn might be necessary. This separate test event would 
increase the costs to the facility and require more oversight by the 
permitting authority. After allowing for additional time to perform a 
SSRA, the findings of the risk assessment could then be used to 
establish site-specific standards which, in turn, might require a 
review of the Title V permit and its associated operating limits/
standards.
    It should also be noted that if the DRE standard is retained under 
RCRA (see discussion in Section III.A.), these same testing 
coordination issues apply to DRE testing. (At sites where SSRAs are to 
be performed, it is expected that DRE

[[Page 24251]]

testing and testing necessary to provide data for SSRAs will be 
occurring at the same time.)
    We invite comment on the workability of this approach for achieving 
maximal coordination of the RCRA trial burns and omnibus findings with 
the initial MACT comprehensive test and Title V permitting.

Part Four: Miscellaneous Issues

I. 5000 Btu per Pound Policy for Kiln Products

    Current Agency policy exempts cement product (clinker) from cement 
kilns burning hazardous waste from regulation as a hazardous waste 
provided the fuel value of the hazardous waste exceeds 5000 Btu per 
pound 68. This allows cement kilns to burn high-Btu 
hazardous waste for energy recovery purposes and still market the 
clinker and the cement mix produced from the clinker as commercial 
product free from any Subtitle C concerns. The Agency has already 
provided a clarification (53 FR 31198, August 17, 1988) that the 
regulations for ``waste derived products'' at Sec. 266.20 do not apply 
to products from processes using hazardous waste (HW) fuels, unless 
these processes also use hazardous wastes as ``ingredients'' in a 
product destined for land application (i.e., the product must 
``contain'' the HW as an ingredient to be covered by Sec. 266.20) or 
burn hazardous waste for destruction. To implement this regulation, the 
Agency has used Btu values of a waste as a proxy to determine whether 
contaminants in the HW fuels will or will not be deemed to transfer to 
the product (i.e., become ingredients). Over time, many commenters have 
submitted data and have suggested that the heat content of a waste is 
an indirect and imprecise way of identifying whether materials should 
be subject to the provisions of Sec. 266.20 (hazardous wastes used in a 
manner constituting disposal).
---------------------------------------------------------------------------

    \68\ Wastes with energy value greater than 5000 Btu may 
generally be said to be burned for energy recovery, since this is 
the Btu value of low grade fuels. 48 FR 11157-59 (March 16, 1983). 
However, lower energy wastes could conceivably be burned for energy 
recovery in industrial furnaces, such as cement kilns, or in 
industrial boilers due to these devices' general efficiency of 
combustion. Id. At 11158. Thus, the 5000 Btu level is not an 
absolute measure of burning for energy recovery (i.e., a rule), 
particularly when industrial furnaces and industrial boilers are 
involved.
---------------------------------------------------------------------------

    The Agency has been interested for some time in considering whether 
and how to change the existing Btu approach. For example, 60 FR 7376 
(February 7, 1995) discusses a possible exclusion of clinker from the 
derived-from rule, even when cement kiln dust is introduced in the 
feed. EPA has also discussed with CKRC the narrower issue of whether 
the 5000 Btu/lb energy value level reliably predicts whether toxic 
contaminants would more likely partition to the clinker and ultimately 
the cement product. Some from industry have suggested that a facility 
that agrees to limit waste feed metals to their ``historic average'' 
could be exempted from the 5000 Btu/hr policy. The rationale is that 
even if the facility took lower Btu waste, they would not be taking 
higher quantities of metal waste than currently, at least on the 
average. This would address EPA's concern about allowing an increase of 
metals in HW fuels burned by cement kilns if the 5000 Btu restriction 
were abandoned.
    Today, without our endorsement at this time, the Agency is offering 
this concept and some potential variations for public comment. The 
Agency is interested in the possible ramifications and requests 
comment, particularly with respect to limiting the concentrations of 
metals in cement products from cement kilns burning hazardous waste. To 
take advantage of such a policy, a facility would have to establish a 
baseline of metals feed in the hazardous waste (for example, the 
average of the previous three years) and then agree to enforceable 
permit conditions limiting metals feedrate levels to that average plus 
one standard deviation. Presumably, enforceable restrictions on metal 
feed rates should control metal partitioning to clinker and CKD much 
more effectively than would the Btu limit and ensure that these 
materials would not contain an increase in toxic metal constituents 
from the hazardous waste used as fuel. Also, metal feed limits based on 
a historical average would appear to be more stringent than the current 
BIF metal feed limits, which are set on a health basis considering 
direct inhalation of metals emissions. (In other words, as discussed in 
earlier sections of this notice, cement kilns are generally feeding 
metals far below allowable BIF limits.)
    EPA seeks comment on allowing cement kilns (and LWAKs) the option 
of complying with the following, which is only partly based on the 
suggestions discussed with cement kiln representatives, with some 
additions:
     An owner or operator of a cement kiln burning hazardous 
waste would be allowed to burn hazardous waste with any Btu content, 
provided the owner or operator agrees to enforceable hazardous waste 
feed operating limits on metals of concern (see below);
     These metals feed limits would be set at levels that would 
ensure, at least on an annual basis, that metals on a mass basis do not 
increase over current levels, which are substantially less than those 
allowable under BIF (and sources would, of course, remain subject to 
stack emission standards to control the emission of metal HAPs);
     Feed limits would have to be established for each of the 
following twelve metals: antimony, arsenic, barium, beryllium, cadmium, 
chromium, cobalt, lead, nickel, selenium, thallium, and vanadium;
     Sampling and analysis would be conducted as often as 
necessary to document that the metals levels are below the limits and 
included in the facility's waste analysis plan required by 40 CFR 
264.13; and
     Results of the analysis would have to be available for 
public inspection.
    Also, the Agency is considering a variation of this option, under 
which kiln operators would have to achieve specified percentage 
reductions of the total quantity (on an aggregate basis) of the 
following metals in their wastes combusted: antimony, arsenic, barium, 
beryllium, cadmium, chromium, cobalt, lead, nickel, selenium, thallium, 
and vanadium. EPA chose these particular metals based on their 
potentially high human health and ecological risk in conjunction with 
their significant tendencies to persist in the environment and 
accumulate in living tissue. If generators reduce metals in wastes over 
time, holding kilns to the average of the past three years may actually 
allow increased burning of certain metal-bearing streams. This is 
because other streams may contain less metals. In contrast, commitments 
to reducing metals below baseline limits would ensure that progress 
continues in waste minimization. EPA requests comments on this option, 
including information about: (1) The prevalence and distribution 
throughout industry sectors of waste streams bearing these metals sent 
to combustion, and (2) opportunities for generators to reduce these 
metals in wastes sent to combustion by means of source reduction during 
generation.
    EPA requests comment on the impact of imposing limits on metals 
concentration on waste streams combusted in cement kilns. EPA raises 
these questions:
     How much hazardous waste now sent to cement kilns for 
energy recovery would be likely to meet such metal level limitations?
     Of the fraction of wastes that would ``fail'' a metals 
limit, would generators of waste now sent to cement kilns reduce metals 
concentrations in these wastes, using waste minimization and pollution 
prevention, so that cement

[[Page 24252]]

kilns would continue to receive the same amounts of waste?
     If no such action to reduce metals concentrations 
occurred, would cement kilns reject high-metals hazardous wastes now 
sent to cement kilns for energy recovery and would these wastes go 
instead to incinerators?
    The Agency also requests comment on the related issue of 
appropriate metals reduction goals. EPA has identified a national goal 
for waste minimization of the most persistent, bioaccumulative and 
toxic hazardous constituents by 25 percent by the year 2000 and by 50 
percent by the year 2005. See EPA's Waste Minimization National Plan 
(Office of Solid Waste, November 1994). Consistent with this national 
waste reduction goal for metals, EPA requests public comments today on 
requiring aggregate percentage reductions for the twelve metals in 
waste feed, as an alternative to holding cement kilns to the historical 
average feed limits of the past three years and allowing no increases 
over baseline limits. This approach would also further waste 
minimization planning by offering kilns a reason to motivate the 
generators supplying them with hazardous waste for combustion to 
undertake waste minimization. In comments related to the role of waste 
minimization in the MACT proposal, Molten Metal Technologies (MMT) 
states that ``without drivers favoring pollution prevention and waste 
minimization in the instant rulemaking, only minimal progress will be 
made.'' MMT points out that economics conspire against pollution 
prevention and waste minimization since investment for compliance often 
takes priority over investment for process modifications to reduce 
waste generation and since corporate rate-of-return thresholds may 
``squash'' pollution prevention and waste minimization initiatives.
    Finally, the Agency requests comment on whether additional nonmetal 
constituents (e.g., chlorinated organics) should also be identified for 
similar reductions as part of this approach.

II. Foundry Sand Thermal Reclamation Units

A. Background
    Foundry operations can generally be classified as either ferrous or 
nonferrous, depending on their primary feed materials. Both types of 
foundries use large amounts of sands for their metal molds. Over time, 
the sands become contaminated with the metals being used, as well as 
with certain binder materials. Nonferrous foundries (i.e., brass, lead, 
etc.) sometimes generate spent sands that exhibit the Toxicity 
Characteristic (40 CFR 261.24) for lead or cadmium. (The Agency has 
indicated concerns with certain sand treatment methods. See 62 FR 
10004, March 5, 1997.) These sands can be physically processed to 
remove contaminants for continued use, resulting in less sand use for 
the foundry, and less need for disposal of the sands. Interest has also 
been expressed in using thermal processing or reclamation units (TRUs) 
to clean the sand for continued use. TRUs may represent a significant 
waste minimization technology for the foundry industry.
    The TRUs remove contaminants primarily by combusting the organic 
binder materials in the sand. These organic materials are generally 
wax-like materials, synthetic or natural (e.g., clays, phenols, etc.). 
Air emissions concerns would include lead, cadmium, and particulate 
emissions, as well as products of incomplete combustion. These units 
are identified as industrial furnaces under 40 CFR 260.10 as a type of 
``foundry furnace'' and are subject to regulation under 40 CFR part 
266, subpart E (the ``BIF rules'') when they burn hazardous 
waste.69 When the Agency developed subpart E, however, we 
did not consider whether TRUs would be appropriately controlled under 
those standards. The Agency created a special exemption for metal 
recovery furnaces under Sec. 266.100(c) and also proposed a special 
exemption for petroleum catalyst recovery units (see 60 FR 57780; 
November 20, 1995). In these two cases, we found that the BIF rules 
would not appropriately control the units in question, i.e., any air 
emissions hazards might be more appropriately controlled under 
standards specially designed for those units under either RCRA or CAA. 
Under RCRA Section 1006, an important consideration for the Agency is 
to avoid duplication to the extent practical between the two Acts. 
Also, as noted above, TRUs may achieve significant waste minimization 
benefits, an important consideration under RCRA.
---------------------------------------------------------------------------

    \69\  Another potential reading of the Section 260.10 definition 
is that ``foundry furnaces'' only applies to a furnace that burns a 
primarily metal-bearing material. Under this reading, TRUs could not 
be industrial furnaces because they burn sand with only contaminant 
levels of metals. However, since TRUs are closely associated, both 
physically and functionally, with the primary metal processing 
functions of a foundry, they are appropriately classified as 
industrial furnaces subject to part 266, subpart E.
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B. Deferral and Variance Options for Consideration
    The Agency is presently developing MACT controls under the CAA for 
foundries. Although at this time it is not clear to what extent TRUs 
would be subject to MACT controls, representatives from the foundry 
industry have suggested that, as the new MACT rules are implemented, 
all foundries with TRUs will be required, as a practical matter, to 
install MACT controls on the TRUs. Among the reasons cited are that 
vendors of TRU technology will have to design for situations under MACT 
control, and state air officials will incorporate the MACT technology 
in permits for foundries as a matter of course.
    Although EPA has no way to predict whether this scenario would come 
to pass, there are obvious advantages to controlling TRUs processing 
sands that exhibit the TC under MACT standards, as opposed to under the 
BIF rules. These advantages include administrative simplicity and 
maximum flexibility for implementing agencies. EPA requests comment on 
the following two approaches to ensure appropriate controls for TRUs:
    1. Deferral option. Given the developments under the CAA discussed 
above, and also in light of the potential waste minimization benefits, 
EPA requests comments on appropriate control schemes for TRUs burning 
hazardous foundry sands. Specifically, comments are requested on a 
deferral of BIF applicability, similar to the existing provision for 
metal recovery furnaces and proposed provision for petroleum catalyst 
recovery units. This would allow development of the foundry MACT, and 
potentially the eventual application of these controls to TRUs 
processing sands that exhibit the TC. Under such an approach, EPA would 
place an exemption in Part 266, Subpart E, identifying foundry TRUs as 
an exempt BIF, and a one-time notice would be required as is now 
required for metal recovery furnaces under Sec. 266.100(c)(1)(I).
    2. Variance from definition of solid waste option. TRUs appear to 
be integral to foundry operations. They are located at the foundry 
site, operated by the foundry, and the sand being processed and 
returned to the foundry operation is essential in the manufacturing 
operation. The time periods between when a spent sand is generated and 
when it is processed and returned is typically a matter of hours. In 
fact, TRUs may reduce the need to store spent sands for processing and 
may thereby reduce fugitive emissions of the sands

[[Page 24253]]

that might result from physical processing. Given that a sand appears 
integral to foundry operations and TRUs can greatly improve the 
efficiency of sand use, EPA could conclude that even without any rule 
changes, foundry operators may be eligible for a variance from the RCRA 
definition of solid waste under the variance provisions found at 40 CFR 
260.30(b), 260.31(b), and 260.33.
    Under these variance provisions, EPA (or an authorized State) may 
grant a variance from the definition of solid waste for materials that 
are reclaimed and then used as feedstock within the original production 
process in which the materials were generated if the reclamation 
process is an essential part of the production process. This evaluation 
is guided by a number of criteria found at Sec. 260.31(b). While 
foundries certainly can and do operate without thermally processing 
their sands, and so TRUs are not literally ``essential'', as summarized 
above the units do in fact greatly increase efficiency of sand use, 
which is an essential raw material of foundry operations. Also, the 
TRUs are physically proximate, and integrated into the foundry's 
operations. Emissions from the TRUs are often ducted into emission 
control devices used for the foundries' main production activities. As 
such, the Agency could view sands being processed in TRUs as 
potentially eligible for the variance under 260.31(b) 70. 
EPA (or the State) would still have to weigh the factors in paragraph 
(b) on a case-by-case basis to determine if the variance should be 
granted. For example, paragraph (b)(3) requires an examination of how 
the sands are handled to ensure that losses are minimized before 
reclamation. Also, paragraph (b)(8) allows consideration of ``other 
factors'' as appropriate, and in this case, air emissions controls for 
the TRU would be appropriately considered before granting a variance. 
As discussed above, controls may be installed as part of the MACT 
process, or simply due to state or local air pollution laws. The Agency 
would expect that as a minimum, emissions of particulate matter would 
have to be limited to control lead emissions, and given the organic 
binder compounds being introduced to the units, limits on and 
continuous monitoring of indicators of efficient combustion, such as CO 
and/or HC, would seem appropriate. Under this approach, the Agency 
might or might not develop special standards for TRUs under RCRA or the 
CAA. The case-by-case approach might enable EPA and the States to 
oversee the units without the need for federal standards.
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    \70\ The Agency notes that, typically, a variance from the 
definition of solid waste under 260.31(b) would apply at the point 
of generation (e.g., in this case, the point where the spent sands 
are removed from the casting forms). Also, typically, when such a 
variance is granted, the variance is only applicable to those 
secondary materials that meet the conditions of the variance (e.g., 
the variance would not include secondary materials that are not 
reused in the production process).
    The normal and efficient flow of materials at facilities with a 
TRU may involve the processing of all of the spent sand generated. 
However, after recovery of the sand, insubstantial amounts of sands 
that are processed by the TRU may be found to be unusable again as 
foundry sand, and so may be discarded. While treatment and disposal 
of the spent foundry sand is clearly not the intent of the TRU, 
``treatment and disposal'' would be the regulatory status of any 
hazardous secondary material that is processed such that it is no 
longer hazardous and then discarded, given the most straightforward 
reading of the regulations.
    Nevertheless, the Agency believes that because the TRU is 
typically integrated into the facility's operations, and the flow of 
spent foundry sand into the TRU becomes a standard operating 
procedure, the incidental discard of an insubstantial amount of 
spent foundry sand should not overshadow the basic purpose of 
Sec. 260.31(b) to grant a variance from the definition of solid 
waste to materials that are reclaimed and reused in the production 
process, where such reclamation is, in effect, an integral step in 
the flow of production. Thus, the Agency asserts that, assuming all 
other conditions of the Sec. 260.31(b) variance are met, the fact 
that a relatively insignificant amount of spent foundry sand is 
discarded would not negate a variance granted to spent foundry sand, 
or require a treatment permit for the TRU.
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III. Status of Gaseous Fuels Generated From Hazardous Waste Management 
Activities

    The proposed rule included a proposed exclusion from subtitle C 
jurisdiction for certain synthetic gas fuels derived from hazardous 
waste treatment activities (61 FR at 17465). Some commenters stated 
that synthesis gas fuels are beyond EPA's regulatory authority because 
they are uncontained gases, and further stated that EPA had failed to 
set out any explanation for its potential jurisdiction over these 
synthesis gas fuels (which jurisdiction EPA proposed to relinquish 
provided the syngas met designated specifications).
    The type of syngas discussed in the proposal results from thermal 
reaction of hazardous wastes, which reaction is optimized to break 
organic bonds and reformulate the organics into hydrogen gas and carbon 
monoxide. Id. This resulting gas can be used as a fuel at manufacturing 
facilities.
    EPA has broad statutory authority to regulate fuels produced from 
hazardous wastes. RCRA section 3004(q)(1); see also Horsehead Resource 
Development Co. v. Browner, 16 F. 3d 1246, 1262 (D.C. Cir. 1994) 
(broadly construing this authority). The fact that syngas (by 
definition) is a gas, rather than a solid or liquid, does not appear to 
raise jurisdictional issues. It is still produced from the hazardous 
wastes that are being processed thermally. See Sec. 261.2(c)(2)(A) and 
(B) (defining such materials as solid wastes). EPA believes its 
authority to be clear under these provisions, but will consider further 
comment on the issue.71
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    \71\ See also 50 FR 49164, 49171 (Nov. 25, 1985); 52 FR 16982, 
17021 (May 6, 1987); and 56 FR 7134, 7203-04 (Feb. 21, 1991) which 
discuss this question, although inconclusively.
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IV. Regulatory Flexibility Analysis

    The Regulatory Flexibility Act (RFA) of 1980 requires Federal 
agencies to consider impacts on ``small entities'' throughout the 
regulatory process. Section 603 of the RFA calls for an initial 
screening analysis to be performed to determine whether small entities 
will be adversely affected by the regulation. If affected small 
entities are identified, regulatory alternatives must be considered to 
mitigate the potential impacts. Small entities, as described in the 
Act, are only those ``businesses, organizations and governmental 
jurisdictions subject to regulation.''
    In preparation of the proposed rule, EPA used information from Dunn 
& Bradstreet, the American Business Directory and other sources to 
identify small businesses. Based on the number of employees and annual 
sales information, EPA identified 13 firms which may be small entities. 
That analysis also determined that the proposed rule was unlikely to 
result in detrimental impacts to small businesses. This conclusion was 
derived from two important findings:
    First, few combustion units are owned by businesses that meet the 
SBA definition. Among those that are considered small (based on number 
of employees), over one-third were found to have gross sales in excess 
of $50 million per year. Furthermore, available data indicate an 
ongoing industry trend toward consolidation, or market exit.
    Second, small entities impacted by the rule, were found to be those 
that currently burn very little hazardous waste, and hence face very 
high cost per ton burned. These on-site facilities are likely to 
discontinue burning hazardous waste and dispose off-site, rather than 
comply with the proposed rule. Based on available data, EPA found that 
the incremental cost of alternative disposal associated with 
discontinued burning of such waste would not exceed 0.10 to 0.20 
percent of annual corporate gross revenues. Furthermore, currently 
viable commercial small business facilities affected by the proposal 
were found to remain profitable.

[[Page 24254]]

    The above findings indicate that the proposed rule is expected to 
have overall negligible impacts on small entities. The Agency is 
currently refining and expanding its analysis of small entities and 
makes no conclusions beyond those presented for the Proposal.

    Dated: April 22, 1997.
Elizabeth Cotsworth,
Acting Director, Office of Solid Waste.
[FR Doc. 97-11155 Filed 5-1-97; 8:45 am]
BILLING CODE 6560-50-P