[Federal Register Volume 63, Number 223 (Thursday, November 19, 1998)]
[Rules and Regulations]
[Pages 64372-64402]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 98-30601]
[[Page 64371]]
_______________________________________________________________________
Part IV
Environmental Protection Agency
_______________________________________________________________________
40 CFR Part 261
Hazardous Waste Management System: Identification and Listing of
Hazardous Waste, Solvents; Final Rule
Federal Register / Vol. 63, No. 223 / Thursday, November 19, 1998 /
Rules and Regulations
[[Page 64372]]
ENVIRONMENTAL PROTECTION AGENCY
40 CFR Part 261
[SWH-FRL-6185-3]
RIN 2050-AD84
Hazardous Waste Management System: Identification and Listing of
Hazardous Waste Solvents
AGENCY: Environmental Protection Agency.
ACTION: Final decision.
-----------------------------------------------------------------------
SUMMARY: The U.S. Environmental Protection Agency (EPA) is issuing a
final decision not to list wastes generated from the use of 14
chemicals as solvents as hazardous under the Resource Conservation and
Recovery Act (RCRA). The determinations in this rule are limited to
specific solvent wastes. This rule is a determination only that the
solvent wastes considered will not be added to the list of hazardous
wastes and is not a determination that the underlying chemicals are
nontoxic in all circumstances in which they are used or discarded.
DATES: Today's final decision will become effective on December 21,
1998.
ADDRESSES: Supporting materials are available for public viewing and
photocopying in the RCRA Information Center (RIC), located at Crystal
Gateway I, First Floor, 1235 Jefferson Davis Highway, Arlington, VA.
The Docket Identification Number is F-98-SLDF-FFFFF. The RIC is open
from 9:00 a.m. to 4:00 p.m., Monday through Friday, excluding federal
holidays. To review docket materials, it is recommended that the public
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/page. The index and some supporting
materials are available electronically. See the FOR FURTHER INFORMATION
CONTACT section for information on accessing them.
FOR FURTHER INFORMATION CONTACT: The RCRA/Superfund Hotline, toll-free,
at (800) 424-9346 or at (703) 920-9810. The TDD Hotline number is (800)
553-7672 (toll-free) or (703) 486-3323 in the Washington, DC
metropolitan area.
For technical information on the RCRA hazardous waste listings,
contact Ron Josephson or Robert Kayser, Office of Solid Waste (5304W),
U.S. Environmental Protection Agency, 401 M Street, SW, Washington, DC
20460. The telephone number is (703) 308-8890.
SUPPLEMENTARY INFORMATION: There are no regulated entities as a result
of this action.
The index and the supporting materials are available on the
Internet: Follow these instructions to access the information
electronically:
WWW: http://www.epa.gov/epaoswer/hazwaste.htm#id
FTP: ftp.epa.gov
Login: anonymous
Password: your Internet address
Files are located in /pub/oswer
The contents of the preamble to this final rule are listed in the
following outline:
I. Legal Authority and Background
A. Statutory and Regulatory Authorities
B. Existing Solvent Listings and the Regulatory Definition of
Solvent
II. Summary of Proposed Rule
A. Determinations Not to List Solvent Wastes as Hazardous Waste
B. Summary of Risk Assessment Supporting the Proposed Rule
III. Peer Review of Calculated Toxicological Benchmarks
IV. Summary of Response to Comments and Rationale for Final Rule
A. Data Collection
1. Representativeness of Industry Characterization
2. Engineering Site Visit Reports
B. Methodology
1. Definition of ``Solvent'
2. Lack of Sampling and Analysis
3. Consistency of Methodology With Other Listing Determinations
4. Plausible Mismanagement Scenarios
C. Risk Assessment
1. Surface Impoundments
2. Tank-Based Management of Wastes
3. Multiple Solvents
4. Comparison with HWIR Exit Levels
5. Environmental Damage Incidents
6. Spills, Leaks, and Overflows
7. Non-Aqueous Phase Liquids
8. Risk Modeling Parameters
9. Comparison with Results of Air Characteristic Study
D. Listing Determinations
1. General Comments
2. Sufficient Regulation of Solvents
3. Waste-Specific Rationales and Response to Specific Comments
V. Regulatory Requirements
A. Regulatory Impact Analysis Pursuant to Executive Order 12866
B. Regulatory Flexibility
C. Unfunded Mandates Reform Act
D. Executive Order 12875: Enhancing Intergovernmental
Partnership
E. Executive Order 13045: Protection of Children from
Environmental Health Risks and Safety Risks
F. Environmental Justice E.O. 12898
G. Paperwork Reduction Act
H. National Technology Transfer and Advancement Act
I. Executive Order 13084: Consultation and Coordination with
Indian Tribal Governments
J. Congressional Review Act
I. Legal Authority and Background
A. Statutory and Regulatory Authorities
The Environmental Protection Agency (EPA) conducted this
investigation and listing determination under the authority of sections
2002(a), 3001(a), (b) and (e)(2) of the Solid Waste Disposal Act (42
U.S.C. 6912(a), and 6921(b) and (e)(2)), as amended by various other
laws, the most comprehensive of which was the Hazardous and Solid Waste
Amendments (HSWA) of 1984. These statutes are commonly referred to as
the Resource Conservation and Recovery Act (RCRA) and are codified at
Volume 42 of the United States Code (U.S.C.), sections 6901 to 6992(k).
Section 3001(a) of RCRA, 42 U.S.C. 6921(a), requires EPA to
promulgate criteria for identifying characteristics of hazardous wastes
and for listing hazardous wastes. Section 3001(b) of RCRA requires EPA
to promulgate regulations, based on these criteria, identifying and
listing hazardous wastes which shall be subject to the requirements of
the Act. Section 1004(5) of RCRA, 42 U.S.C. 6903(5), defines the term
``hazardous waste.'' There are two types of hazardous waste. First,
hazardous wastes are those solid wastes which may cause or
significantly contribute to an increase in mortality, serious
irreversible illness, or incapacitating reversible illness. Second,
hazardous wastes are those solid wastes which may pose a substantial
present or potential hazard to human health or the environment when
improperly managed. Id.
EPA's regulations establishing criteria for listing hazardous
wastes are codified at Title 40 of the Code of Federal Regulations
(CFR) 261.11 (40 CFR 261.11). Section 261.11 presents three criteria by
which EPA identifies wastes as hazardous.
First, solid wastes may be classified as ``characteristic'' wastes
if they exhibit any of the characteristics of hazardous waste
identified at 40 CFR 261.21-24 (i.e., ignitability, corrosivity,
reactivity, or toxicity).
Second, solid wastes may be listed as acutely hazardous if they are
fatal to humans at low doses, lethal in animal studies at particular
doses designated in the regulation, or otherwise capable of causing or
significantly contributing to an increase in serious illness.
Third, solid wastes may be listed as hazardous if they contain any
of the toxic constituents identified in Appendix VIII of 40 CFR part
261 and the Agency concludes, after considering the eleven factors
enumerated in 40 CFR 261.11(a)(3), that the waste is capable of
[[Page 64373]]
posing a substantial present or potential hazard to human health or the
environment when improperly managed. A substance is listed in Appendix
VIII if it has been shown in scientific studies to have toxic,
carcinogenic, mutagenic, or teratogenic effects on humans or other life
forms. Today's listing determination has been made pursuant to this
third set of criteria.
As part of its regulations implementing section 3001(b) of RCRA,
EPA published a list of hazardous wastes that includes hazardous wastes
generated from nonspecific sources (F-wastes) and a list of hazardous
wastes from specific sources (K-wastes). These lists, published at 40
CFR 261.31 and 261.32, respectively, have been amended several times.
Persons who generate, transport, treat, store, or dispose of wastes
listed as hazardous must do so subject to Federal requirements under
RCRA. Facilities that must meet the hazardous waste management
requirements, including the need to obtain permits to manage hazardous
wastes, are commonly referred to as RCRA Subtitle C facilities. EPA
standards and procedural regulations implementing Subtitle C are found
generally at 40 CFR parts 260 through 279.
Solid wastes that are not hazardous wastes may be disposed of at
facilities that are overseen by State and local governments. These
facilities are referred to as RCRA Subtitle D facilities. EPA
regulations affecting Subtitle D facilities are found generally at 40
CFR parts 240 through 247, and parts 255 through 258.
Section 3001(e)(2) of RCRA requires EPA to determine whether to
list as hazardous several specified wastes, including solvent wastes.
The Environmental Defense Fund (EDF) and EPA entered into a consent
decree to resolve issues raised in a civil action brought by EDF (EDF
v. Browner, Civ. No. 89-0598 (D.D.C.)) in which the Agency agreed,
among other things, to a schedule for making a listing determination on
spent solvents. This listing determination is to consider spent
solvents, still bottoms from the recovery of these solvents, and spent
solvent mixtures when the following chemicals are used as solvents:
cumene, phenol, isophorone, acetonitrile, furfural, epichlorohydrin,
methyl chloride, ethylene dibromide, benzyl chloride, p-
dichlorobenzene, 2-methoxyethanol, 2-methoxyethanol acetate, 2-
ethoxyethanol acetate, and cyclohexanol.
For an additional set of seven solvents, EPA agreed to conduct a
study and issue a final report by August 30, 1996. This study, which
EPA completed on August 22, 1996, discusses the wastes associated with
the use of the materials as solvents, the toxicity of the wastes, and a
description of the management practices for the wastes.
Solvent uses are found throughout various industries and, thus,
would fall under the category of wastes from nonspecific sources (F-
wastes) if listed in 40 CFR 261.31. In fact, wastes designated F001
through F005 are various wastes from solvent uses of a number of
chemicals. In today's action, EPA has decided not to amend 40 CFR
261.31 to add wastes generated during the use of the 14 chemicals of
concern as solvents.
EPA emphasizes that the determination not to list these wastes only
means that the Agency has found it is not appropriate to list as
hazardous the wastes across broad industry categories that could result
from solvent uses of the 14 chemicals. As will be more fully explained
below, EPA did not find that solvent uses for these chemicals, in
general, produce hazardous wastes that require listing. Many of the
wastes examined are hazardous already because they are characteristic
wastes under 40 CFR part 261, subpart C, or contain other solvent
wastes currently listed as hazardous. In addition, some of the
chemicals may produce wastes that are hazardous when used in ways other
than as solvents, perhaps as catalysts, feedstocks or other uses in
chemical manufacturing processes. Solvents use simply does not
constitute an appropriate way to designate these chemicals as a
hazardous waste category under RCRA for wastes from nonspecific
sources. Particular industrial wastes from these chemicals might be
hazardous, but such wastes were not examined in this determination.
B. Existing Solvent Listings and the Regulatory Definition of Solvent
Five hazardous waste listings for specific solvents have been
promulgated to date: F001, F002, F003, F004, and F005. These are found
at 40 CFR 261.31. Today's decision applies the same criteria for
defining solvent wastes as are applied to these existing solvents
listings. These criteria are explained in the Federal Register of
December 31, 1985 (50 FR 53316) and are also consistent with the
requirements of the EDF Consent Decree.
The December 1985 document amended the solvent listings to include
spent solvent mixtures when the solvent, before it is used, contains 10
percent or more of total listed solvents. The original listing included
only the technical grade, practical grade or pure form of the solvents
when used. This threshold level was considered by the Agency to be well
below the minimum solvent concentration typically used in solvent
formulations and was designed to bring the majority of listed solvent
mixtures used in commerce into the hazardous waste management system,
while excluding dilute mixtures or de minimis concentrations.
In addition, the document issued several clarifications to the
original listings. First, the listings apply to ``spent'' solvents--
those that are no longer fit for use without being regenerated,
reclaimed, or otherwise processed. (See 40 CFR 261.1(c) (1) and (4);
261.2(c) (3) and (e)). Second, the listings cover only those solvents
used for their solvent properties--``to solubilize (dissolve) or
mobilize other constituents.'' These include solvents used in
degreasing, cleaning, fabric scouring, as diluents, extractants,
reaction and synthesis media. The document stated that the listings do
not cover wastes from the processing of products where a chemical that
might be used as a solvent is, instead, used as a reactant or where a
chemical is used as a solvent only as an ingredient in the formulation
of a commercial chemical. This latter category would include chemicals
used as a solvent in paint formulations to dissolve the paint itself.
These uses do not generate ``spent solvent'' wastes. The wastes of
concern for these products would be the production process wastes or
wastes from the use of the product, not the solvent itself.
This approach is also consistent with the requirements of the EDF
Consent Decree. This is because the consent decree identifies a subset
of solvent wastes that are potential candidates for listing and
specifies that the listing determination applies to ``spent solvents,''
a term that tracks the language of the existing listings. Moreover,
this approach had been the longstanding approach of the Agency to
dealing with solvent listings at the time the Consent Decree was
negotiated and should be interpreted as representing the understanding
of the parties.
This approach, whereby EPA has limited the scope of this rulemaking
through this focused definition of solvents subject to the listing, is
a reasonable interpretation of RCRA and is consistent with EPA's
historical treatment of solvent listing descriptions. Use of the
definition has allowed the Agency to place reasonable limits on the
scope of its listing investigation for this rulemaking. RCRA 3001(e)(2)
directs
[[Page 64374]]
EPA to make a listing determination on ``solvents,'' but provides no
further direction on the meaning of that term. EPA, therefore, has the
discretion to reasonably define the scope of the listing determination.
Given the ubiquity of solvents, the great variety of uses and the huge
differences in the composition of the waste streams, EPA could not
gather the evidence to list ``solvent wastes'' as a general category.
Under the Agency's regulations at 40 CFR 261.11(b), wastes may be
listed as a category if they are ``typically or frequently'' hazardous.
EPA could make no such findings for ``solvent'' wastes in general and,
therefore, has reasonably focused its investigation and listing
decision.
As noted above, the existing solvent listings are limited to spent
solvent mixtures when the solvent, before it is used, contains 10
percent or more of total listed solvents. While wastes from this use
threshold were the primary focus of today's listing determination, EPA
also considered in its evaluations the few solvent uses that were
reported to be below the 10 percent threshold.
In a previous proposed hazardous waste listing for wastes from the
production of dyes and pigments (59 FR 66072, December 22, 1994) EPA
presented the general approach the Agency uses for determining whether
to list a waste as hazardous pursuant to 40 CFR 261.11(a)(3). The
discussion focused on the selection of waste management scenarios used
in assessing risk and the use of information on risk levels in making
listing determinations. This approach was further developed in EPA's
listing for petroleum refining process wastes (proposed rule published
at 60 FR 57747, November 20, 1995; final rule published at 63 FR 42110,
August 6, 1988). EPA is employing the same general approach in this
final rulemaking. Readers are referred to these documents for a
description of EPA's listing policy. Also, section II.C.2. of the
proposed rule, ``Risk Assessment,'' contains a discussion of how
elements of EPA's listing policy were applied in today's listing
determination.
The following section contains a summary of the methodology used to
arrive at the no-list determinations in today's document. For more
details on this methodology, see the proposed rule, background
document, and the response to comments document in the docket.
II. Summary of Proposed Rule
A. Determinations Not To List Solvent Wastes as Hazardous Waste
EPA proposed the decision not to list the spent solvent wastes from
the 14 chemicals noted above on August 14, 1996 (61 FR 42318). The
Agency determined that these wastes did not meet the criteria for
listing set out in 40 CFR 261.11. The proposed rule presented the waste
characterization, waste management, mobility, persistence, and risk
assessment data that were the bases for the Agency's proposed decision
not to list these wastes as hazardous. Further details of EPA's
approach are presented in the Hazardous Waste Listing Determination
Background Document for Solvents (hereafter known as ``Listing
Background Document'') in the docket for the proposal to today's rule.
As explained in section II.B of the proposed rule, spent solvents
differ from other listed wastes among EPA's waste listings in that the
solvents are used in manufacturing and allied processes rather than
being the principal waste streams generated by manufacturing processes.
In order to characterize industrial solvent use, the Agency sent out
almost 1,500 preliminary questionnaires to cover the 21 total chemicals
(14 from the listing determination and seven from the study). An
additional 60 facilities were surveyed on their use of these chemicals
as solvents through the chlorinated aliphatics industry survey. EPA
then sent out a full RCRA section 3007 survey to facilities using
greater than a combined total of 1,200 kilograms of all the chemicals
of concern.
The Agency consulted various literature and reference sources, such
as Chemical Abstracts, general reference books, the Agency's Toxic
Release Inventory (TRI) compiled under section 313 of the Emergency
Planning and the Right-to-Know Act (EPCRA), databases compiled for
various EPA programs dealing with air and water pollution, and
information available from trade associations. Of the 14 chemicals
involved in the listing determination, 11 were on the TRI. Use of the
literature, Chemical Abstracts, TRI, and other EPA databases allowed
the Agency to focus on the industries that actually use these chemicals
as solvents. In addition, many of these sources gave strong indications
as to when major uses of a chemical were not as a solvent.
Once the Agency narrowed down the potential solvent-using
industries, the Agency developed a list of facilities to survey about
their solvent use. These facility names and addresses were obtained
again from a variety of sources, including TRI, trade associations, and
other Agency media program sources. The Agency sent a short
(``preliminary'') questionnaire to approximately 1,500 facilities
inquiring about uses of any of the 14 listing determination chemicals
as solvents and the quantities used.
The Agency used the preliminary questionnaire data to develop the
large questionnaire mailing list and to organize site visits. The
Agency also made several hundred confirmatory telephone calls to
determine that reported information was correct. The data from the
preliminary questionnaire showed the Agency several distinct patterns
of solvent use: facilities that use large amounts of any of these
chemicals as solvent, those that use small quantities as solvents, and
those that use none of the chemicals as solvents. The Agency found that
a solvent use quantity of 100 kg per month, or 1,200 kg per year,
provided a mathematically convenient separation of those facilities who
use large amounts of solvent and those who use very little and provided
an indication as to which facilities were likely to be large quantity
generators of hazardous waste based on use of these chemicals as
solvents. Based on careful analysis of the data, the Agency identified
likely large-scale users of these chemicals as solvents.
The Agency then developed the large questionnaire. This
questionnaire reconfirmed data on solvent use and requested detailed
information on a facility's solvent-using processes, waste generation,
waste management, and waste minimization activities. The Agency sent
this questionnaire to approximately 150 facilities that indicated to
the Agency through the preliminary questionnaire that significant
solvent uses of these chemicals exist. The data obtained from the
questionnaire were applied to the risk assessment process described in
today's document as well as the preparation of the background document.
To summarize the results, 4 of the 14 chemicals showed no use as a
solvent. The remaining 10 chemicals were analyzed in the Agency's risk
assessment based on solvent uses found by the Agency. For the 10
chemicals of the required listing determination for which there were
solvent uses (acetonitrile, 2-ethoxyethanol acetate, 2-methoxyethanol,
2-methoxyethanol acetate, cyclohexanol, cumene, phenol, furfural,
isophorone, and methyl chloride), EPA found that the management of
residuals from the use of these chemicals as solvents did not pose a
risk to human health or the
[[Page 64375]]
environment under the plausible management scenarios assessed. The data
used as the bases for these determinations were presented in sections
II.D through II.M of the proposed rule (61 FR 42327). Detailed
information is also presented in the background documents supporting
the proposed rule (RCRA Docket number F-96-SLDP-FFFFF).
Specifically, none of the solvents satisfy the criteria for listing
in 40 CFR 261.11 (a)(3). For acetonitrile, 2-methoxyethanol, and methyl
chloride, while risk analyses indicated some potential risk from air
releases of these chemicals from onsite accumulation in open tanks, EPA
believes this risk would not be significant because most, or in some
cases all, of the nonwastewater residuals are already regulated as
hazardous waste. For phenol, 2-ethoxyethanol acetate, furfural, cumene,
cyclohexanol, isophorone, and 2-methoxyethanol acetate, the risk
estimates indicated that spent solvent residuals from the use of these
chemicals as solvents do not pose a substantial risk or potential
hazard to human health or the environment through the plausible
management scenarios and pathways assessed.
For the remaining four chemicals subject to the required listing
determination in the EDF Consent Decree (1,4-dichlorobenzene, benzyl
chloride, epichlorohydrin, and ethylene dibromide), EPA proposed not to
list residuals from their use as solvents, because the data collected
by EPA showed that these chemicals are extremely unlikely to be used as
solvents. One of the chemicals (p-dichlorobenzene) is a solid at room
temperature, and the other three (benzyl chloride, epichlorohydrin, and
ethylene dibromide) are relatively reactive chemicals not well suited
to solvent use. EPA's information showed that the very limited solvent
use reported for these four chemicals is linked to bench-scale or
experimental laboratory settings, and no significant solvent uses were
found. For more detail see sections II.N through II.Q of the proposed
rule (61 FR 42347) and background documents supporting the proposed
rule (RCRA Docket number F-96-SLDP-FFFFF).
B. Summary of Risk Assessment Supporting the Proposed Rule
As described in detail in the proposed rule (see 61 FR 42322-
42327), EPA carried out various analyses to determine the potential
risk that might arise from the disposal of the spent solvent wastes
under study. In carrying out the modeling for these assessments, EPA
used available data it collected from industries using these solvents.
The Agency used information gathered in the RCRA 3007 Questionnaires
and site visits related to the waste characteristics, waste management
practices, and potential pathways for release and exposure. EPA used
other generic input parameters to fate and transport models to estimate
the risk a waste might present under management scenarios known to
occur. The data used in the modeling efforts included the
concentrations and toxicity of the solvent constituents in the waste,
the mobility and fate of such constituents in different disposal
scenarios, likely exposure routes under these scenarios, and the
location of receptors that might be exposed.
The levels of receptor exposure estimated from modeling were
compared with toxicological benchmarks to evaluate the potential health
impacts. For noncarcinogenic constituents, EPA used reference doses for
ingestion exposure (RfDs) and reference concentrations for inhalation
exposure (RfCs); these are measures of acceptable daily intakes for a
specific chemical. To assess the hazard to a hypothetical individual,
EPA used hazard quotients (HQs). An HQ is the ratio of the modeled
exposure (or dose) received compared with the acceptable daily dose
(the RfC or RfD). An HQ above one indicates that exposures may occur
above acceptable levels. For carcinogenic constituents, EPA compared
exposure levels to carcinogenic potency estimates (carcinogenic slope
factors, or CSFs) to calculate specific risk levels. The carcinogenic
risks results are expressed in terms of individual risk, reflecting the
additional incidence of cancer that may occur in an exposed population.
For example, a risk of 1 x 10-5 (which will be presented
in this document as 1E-05) corresponds to a probability of one
additional case of cancer for every 100,000 people exposed.
EPA used verified RfDs, RfCs, or CSFs when available in EPA's
Integrated Risk Assessment Information System (IRIS). IRIS, which
represents a consensus opinion of EPA health scientists, is a database
of human health effects that may result from exposure to various
substances found in the environment. For the chemicals that did not
have complete verified IRIS data available (2-methoxyethanol acetate,
cyclohexanol, phenol, and isophorone), EPA calculated provisional
values when needed for use in the listing determinations.
EPA performed a number of different types of risk analyses. First
the Agency completed a ``bounding analysis'' to screen out solvent
wastes from further consideration. In this analysis, the key input
parameters were set to their ``high-end'' values (typically the 90th
percentile point on the distribution of values available for each
parameter). For solvent wastes that did not ``bound out,'' EPA then ran
a high-end ``deterministic'' sensitivity analysis to determine which
high-end input parameters result in the greatest risk. EPA calculated
risks for all combinations when the most sensitive parameters were set
at high-end values and then used the highest ``high-end'' risk. In this
way, EPA attempted to estimate ``high-end'' risks that were somewhere
above the 90th percentile, i.e., the risks would be below this level
for at least 90% of the population at risk. EPA also calculated
``central tendency'' risks, which correspond to the risk when all input
parameters were set at their median value.
Critical decisions for risk assessment include EPA's determination
regarding which waste management scenarios to model and how to use the
information on waste volumes and solvent concentrations disposed as
modeling input. The Agency's modeling focused primarily on potential
releases from wastes managed in aerated tanks, stored in open tanks,
undergoing thermal treatment, and managed in surface impoundments.
Modeling was based on the information EPA collected from facilities,
including quantities of wastes managed. For each management scenario,
EPA evaluated the full range of direct and indirect pathways through
which the solvents could affect human health or the environment. Based
on the physical and chemical properties of the constituents of concern
and plausible management practices, certain routes of exposure for some
scenarios were not considered to pose threats and were not further
evaluated.
In general, solvent wastes fell in several major categories.
Wastewaters were typically diluted aqueous wastes that are managed in a
biological treatment system (usually in tanks). Nonwastewaters includes
two subcategories. These include: (1) wastes with high levels of
solvents or other organic chemicals, which were sent for thermal
treatment in incinerators, industrial boilers, or fuel blenders, and
(2) treatment residuals, such as wastewater treatment sludges or
incinerator ash, which contained negligible levels of solvents.
EPA modeled storage in an open tank and thermal treatment for
nonwastewater spent solvent residuals from use of all of the ten
solvents. EPA modeled wastewater treatment in
[[Page 64376]]
aerated tanks for wastewater residuals resulting from the use of
acetonitrile, 2-methoxyethanol, 2-ethoxyethanol acetate, phenol,
furfural, and cumene as solvents.
The surface impoundment scenario was assessed for five of the
solvents; acetonitrile, phenol, cumene, furfural, and methyl chloride.
For acetonitrile and cumene, the headworks concentrations (i.e., the
concentrations after the spent solvent was mixed with other wastewaters
at the headworks of the wastewater treatment system) potentially
discharged to surface impoundment were below the health-based levels
for these constituents, and thus were not evaluated further. For
phenol, three wastewaters with spent phenol were reported to be managed
in surface impoundments that are part of a wastewater treatment train.
In two of these cases, the phenol concentration was below the drinking
water health-based level after mixing at the headworks, prior to
reaching the surface impoundment. In the third case the stream had
levels ranging above the health-based level; however this level is
expected to be efficiently treated by the activated sludge, such that
little phenol would be available for release to groundwater. For methyl
chloride, EPA modeled air releases from treatment in a surface
impoundment, but not the groundwater pathway because the impoundment
was a permitted hazardous waste management unit. (As described below,
the unit treating methyl chloride wastes was unique due to the highly
specialized nature of this solvent use). EPA modeled treatment in a
surface impoundment for furfural; however, bounding analyses showed no
significant risks via air or groundwater pathways. The solvent use of
the chemicals modeled in surface impoundments are very specialized.
This means that they have properties that only allow very particular
solvent uses in a very narrow set of circumstances and only for some
industries, or even for only one. For example, methyl chloride is a gas
at room temperature, which severely limits its utility as a solvent.
The only significant solvent use for this chemical is as a solvent in
the polymerization of butyl rubber, during which methyl chloride is
passed through aluminum chloride to form and solubilize the catalyst
used. The chemical's special ability to generate such a catalyst
solution is why it is used. Similarly, by far the largest solvent uses
of furfural and phenol are in the extraction of a high molecular weight
oil (lubrication oil) during petroleum refining; these chemicals have
very limited solvent uses outside the petroleum industry. Therefore,
EPA has a high degree of confidence that the concentrations of
chemicals in the streams flowing into surface impoundments studied in
this listing determination are representative of the universe of such
uses and possible exposure scenarios.
The landfill scenario was initially assessed for acetonitrile,
methyl chloride, cumene, and cyclohexanol, but not modeled for spent
solvent residuals from any of these solvents because the concentrations
in the wastes were ``trace'' or ``negligible.'' Further general
background for the risk assessment is provided in the preamble to the
proposed rule (see 61 FR 42318).
III. Peer Review of Calculated Toxicological Benchmarks
Standard inhalation toxicological benchmarks were not available to
EPA for four of the solvents when the Agency was conducting the risk
assessment for the proposed rule. The Agency therefore calculated
values specifically for the rule. EPA has labeled these toxicological
benchmarks ``provisional RfCs'' to clearly differentiate them from the
Agency consensus values listed on IRIS. During the comment period, EPA
solicited peer review of these calculated risk values. The peer review
reports and the complete Agency response to the reports are in the
docket for this rulemaking.
In response to comments received in the peer review reports, EPA
adjusted three of the provisional toxicological benchmarks used for
this risk assessment. The changes are shown in Table 1.
Table 1.--Changes in Toxicological Benchmarks for Air Pathway
----------------------------------------------------------------------------------------------------------------
Previous New
provisional provisional
Solvent NOAEL \1\ (mg/m3) toxicological toxicological
benchmark (mg/ benchmark (mg/
m3) m3)
----------------------------------------------------------------------------------------------------------------
Cyclohexanol............................ 0.06.................................. 0.00006 0.00002
Phenol.................................. 19.................................... 0.019 0.006
Isophorone.............................. 37 (LOAEL) \2\........................ 0.0037 0.012
----------------------------------------------------------------------------------------------------------------
\1\ No observed adverse effect level.
\2\ Lowest observed adverse effect level.
The new benchmarks for cyclohexanol and phenol reflect additional
uncertainty factors to account for insufficient toxicity databases. The
benchmark for isophorone reflects a reduction in overall uncertainty
factors to reflect Agency guidance limiting such factors to a total of
3,000. Full documentation of the methodology for developing these
benchmarks is in the docket for this rulemaking.
In addition, the toxicological values for cumene were changed on
IRIS during the comment period. The RfD (for noncancer ingestion risks)
was changed from 0.04 mg/kg/day to 0.1 mg/kg/day. The RfC (for
noncancer inhalation risks) was changed from 0.009 mg/m\3\ to 0.4 mg/
m\3\. These changes both reflect greater tolerance for cumene than the
previous benchmarks and thus have no impact on EPA's decision not to
list wastes derived from the use of this chemical as a solvent.
The Agency has employed these revised ``provisional RfCs'' for all
the updated risk assessments involving these solvents for the final
rule. In addition, the Agency has re-estimated risks assessed for the
proposed rule using these new benchmarks. Documentation of these re-
estimations appears in the supplemental risk assessment background
document to this final rule. The final risk estimates for all the
solvents are shown in Table 3 of this preamble.
In all cases the changes to the toxicological values do not have
any significant impact on EPA's risk results, nor do the changes affect
any listing decisions. The solvent wastes for the chemicals examined
still do not pose significant risks, and thus, these analyses confirm
the proposed decisions not to list these wastes.
[[Page 64377]]
IV. Summary of Response to Comments and Rationale for Final Rule
The Agency is responding in this preamble to the most significant
comments received in response to the document of August 14, 1996, 61 FR
42318. Other comments received by the Agency are addressed in the
document entitled Hazardous Waste Listing Determination: Spent
Solvents, Response to Comments (hereafter known as Response to Comments
Document) that is available in the docket associated with this
rulemaking.
The Agency is responding to a variety of comments concerning data
collection, methodology, risk assessment scenarios, and issues specific
to each chemical in this listing determination. The responses, while
touching many specific aspects of the listing determination effort,
involve three major themes:
The Agency used a very thorough survey, which
characterized the risks of the spent solvents. The Agency researched
various potential applications of these chemicals as solvents and found
that solvent uses are confined to a limited set of industrial
applications. Data collected from the questionnaires confirmed the
general lack of wide solvent use, and are consistent with EPA's search
of the literature. These findings allowed the Agency to consider the
applicable waste generation and management practices, and define
plausible management scenarios for use in evaluating potential risks
associated with these solvent wastes.
Facilities use the solvents for specific purposes that
vary by the desired process. Some of the solvents in this listing
determination have different applications over certain industries
(i.e., acetonitrile). Even within one industry, the primary commonality
among the processes is the solvent constituent itself. Other solvents
were used in very limited ways and their primary uses were highly
specialized (e.g., furfural). However, even for solvents with
specialized uses, other minor uses were typically reported for
different industries and processes. The resulting potential variability
in waste compositions led the Agency to focus its efforts on evaluating
the solvent constituent itself. The Agency believes it has captured the
risks that arise from the solvents themselves, and that this is a
reasonable approach to fulfilling its listing determination
obligations.
Little to no benefit would accrue from regulating these
wastes because many are already regulated and treated as hazardous
wastes. These solvent wastes, particularly nonwastewaters with a high
organic content, are characteristically hazardous or mixed with other
listed wastes, and are generally thermally treated. Other
nonwastewaters, such as wastewater treatment sludges or filter media,
do not contain measurable levels of the solvent constituents, and thus
present no significant risks.
A. Data Collection
1. Representativeness of Industry Characterization
One comment argues that EPA cannot fully characterize industry
solvent management practices because the facilities that may be
affected are too numerous to predict and specifically identify.
Therefore, the Agency should project standard mismanagement scenarios
in order to examine the full range of actual and potential waste
management practices applicable to the wastes. This is the only way the
Agency can discharge its mandate to protect human health and the
environment.
In response, EPA disagrees that it is not possible to predict and
identify, as a practical matter, the facilities that may be affected.
It is possible and appropriate to do so and EPA has, in fact,
accomplished that purpose, as summarized below and explained more fully
in the Response to Comments Document. The Agency outlined the general
approach to the data collection process in the proposal (61 FR 42321-
42322). To summarize, the Agency began collecting data on all 14
chemicals involved in the listing determination (plus the seven in the
Solvents Study) as a means of collecting background information on
these chemicals. The Agency identified solvent uses through cross-
referencing SIC codes in known and suspected process industries with
data found in the TRI, Office of Water facility lists, and many other
data sources. The Agency used many different facility address lists to
create a list of potential solvent-using facilities.
The sources used by the Agency provide a comprehensive view of the
types of uses of these chemicals as solvents and the quantities used.
The Agency identified industries using the 14 chemicals as solvents by
conducting literature searches including Chemical Abstracts, the
Chemical Engineering Handbook, the Industrial Solvents Handbook, and
the SRI Chemical Economics Handbook. As today's document and the
associated background documents explain, the process was a logical,
iterative, step-by-step process. The chemicals in question are not
likely to be widely used as solvents (with the exception of
acetonitrile and, to a more limited extent, 2-methoxyethanol, which
have significant solvent uses in some industries), because they have
properties that limit their use to specific situations, and are
generally noncompetitive in price. In addition, the Agency's data
collection methodology combined a comprehensive view not only of the
chemical's solvent use, but also of nonsolvent uses to confirm use
data. The specificity of applications for these solvents, while
sometimes cutting across more than one industry, is still limited
enough that the listing determination could stay focused on the actual
management scenarios found through questionnaires and site visits. The
Agency is confident that the waste management practice data found in
this investigation are adequate for risk assessment modeling, and that
using other modeling practices not found would only lead to using
hypothetical waste data that do not represent any activities that
resemble reality. To engage in this kind of hypothesis would be likely
to result in forcing significant additional costs on the public with no
incremental risk reduction from regulating the wastes in question. The
Agency notes that no commenter identified any specific solvent users of
these chemicals not already found by the Agency. Also, the commenter
could not suggest any alternative to the Agency's methodology other
than a listing based on hypothetical uncertainties--an approach not
justified by the data.
The Agency sent almost 1,500 preliminary questionnaires asking
facilities how much of each chemical was used as a solvent in 1991 and
1992. The data showed that the Agency was successful in identifying
many solvent users, although more than 900 facilities were eliminated
from further consideration because they did not use any of the
chemicals as a solvent. The Agency was also able to eliminate another
400 facilities from consideration to receive the final questionnaires
due to reporting errors, discontinued use, or reported use of small
quantities of the solvents. The fact that the vast majority of
facilities that received the preliminary questionnaire reported no
solvent use supports EPA's view that many potential solvent users, in
fact, do not use these chemicals this way. The Agency found that
reported uses of very small quantities of the chemicals as solvents
were often inaccurate, but facilities reported these quantities to err
on the side of caution. The remaining
[[Page 64378]]
156 facilities received a large, detailed questionnaire requesting
information on solvent uses and waste generation and management
practices. The listing determination is based on these data.
The details of the data collection effort also brought another
point to the Agency's attention. While other solvents are used in
countless industries and facilities and would be difficult to
characterize, the particular set of solvents in this listing
determination has much more limited applicability. EPA's literature
search found these chemicals to have many and varied ``nonsolvent''
uses. Data collected from the questionnaires confirmed the general lack
of wide solvent use, as discussed below.
While reference sources (e.g., SRI Chemical Economics Handbook)
indicated many of these chemicals are produced in fairly high
quantities, these references reported significant quantities used as
solvent for only four of the fourteen chemicals studied: acetonitrile,
2-methoxyethanol, furfural, and methyl chloride. This is consistent
with what EPA found in its 3007 Survey for these four chemicals.
Furthermore, as described in the Listing Background Document and the
proposed rule, the solvent uses of furfural and methyl chloride were
limited to a single specialized use in each case, and these users were
fully surveyed. Solvent use quantities were not reported in reference
sources for the other ten chemicals. Four of the ten were those for
which EPA also found no solvent uses (benzyl chloride, epichlorohydrin,
ethylene dibromide, and p-dichlorobenzene). For an additional four,
EPA's Survey found that the amounts of the production quantities used
as a solvent were small compared to total production (cumene-0.026%;
cyclohexanol-<0.1%; 2-ethoxyethanol acetate-1.2%; isophorone-1.7%);
this is also consistent with the lack of significant quantities of
solvent use reported in reference sources.
The remaining two chemicals are special cases. The domestic
production of 2-methoxyethanol acetate is reported to have ceased, and
the small volume of total solvent use found by EPA in its Survey (1,673
kg/year) confirms the lack of significant solvent use. EPA did find
significant solvent use of the final chemical, phenol, which was not
reported in most other reference sources. However, nearly all (>99%) of
the solvent use quantity found in the Survey was from one facility that
produces phenol for its own captive use. This ``native'' phenol is
produced as a byproduct of other processes, and would not be reported
in production or use data in reference sources. Leaving out this volume
from one facility, EPA's Survey shows that the fraction of phenol
production that is used as a solvent is low (<0.2%), which is
consistent with the lack of any significant solvent use quantities
reported in reference sources. In any case, the vast majority of phenol
solvent use reported in the 3007 Survey was a very specialized use; the
petroleum industry uses phenol to extract lube oil from residual oil.
EPA surveyed all petroleum refiners in its Survey; thus EPA is
confident the Survey captured all major solvent users for this
chemical.
The Agency disagrees that it should project standard mismanagement
scenarios not indicated by the data, because the rationales for
selection of a particular set of plausible management scenarios are
specific to each solvent. Based on the general rationale just discussed
and the data for each of the chemicals as given in detailed discussion
in the Response to Comments Document for each of the chemicals, the
Agency has confidence in the data set as the best available effort to
assess the chemical use universe and actual waste generation and
management scenarios. Merely developing hypothetical waste generation
and management scenarios, as suggested by the comment, has no sound
basis in fact. This would lead to the danger of over regulating risks
that do not exist and siphoning off scarce resources to deal with those
non-risks, rather than risks that may be more worthy of the public's
attention.
For these solvents, the Agency has no reason to project management
scenarios beyond what was found through questionnaires and site visits.
The Agency found the vast majority of wastes managed in tanks and
incinerators. Where a waste was managed in a surface impoundment, the
Agency performed that modeling under high-end exposure assumptions. The
Background Document to the proposal and the Response to Comments
Document both present more detailed assessments of how each individual
chemical is used, what wastes are generated, and what management
scenarios were selected. For example, no management scenarios were
selected for p-dichlorobenzene, epichlorohydrin, ethylene dibromide,
and benzyl chloride because none of these chemicals are used as
solvents. For most other chemicals, the uses are extremely limited and
specific. See the sections devoted to the individual chemicals for
specific rationales, and the discussion of management scenarios in
section IV.B.4.
Below, EPA responds to the specific issues raised in comments that
the Agency's survey was inadequate to characterize the solvent uses and
mismanagement scenarios.
One commenter pointed out that EPA surveyed only a small percentage
of facilities within very few SIC codes. The commenter stated that for
several solvents, the quantity of sectors potentially affected
outnumbers the quantity of facilities forming the basis for EPA's
plausible mismanagement conclusions. As an example, the commenter
stated that for 2-methoxyethanol acetate, EPA identified seven
industrial sectors potentially affected by this chemical, but sent only
the questionnaire to three facilities using the solvent.
The Agency disagrees with this comment. As previously mentioned,
this listing determination covers 14 chemicals used as solvents. In
order for the Agency to determine the universe of facilities
potentially affected by this listing determination, it sent out
preliminary information surveys to obtain basic solvent use
information. The Agency sent this survey to nearly 1500 facilities
based on an evaluation of chemical usage. Given this large universe of
facilities and the potential to obtain useful information on solvent
use in this mailing, the Agency also decided to include in this
preliminary questionnaire questions concerning seven other chemicals
(in addition to the 14 already included in this listing determination)
which it was also investigating under a Solvent Study mandated by the
court.
The prequestionnaires showed that about 600 facilities reported any
possible use of one or more of the chemicals as solvents. The Agency
conducted further evaluations and screening and identified 156
facilities to which it sent the more detailed ``full'' questionnaire
concerning the use of the 21 chemicals as solvents (14 for this listing
determination and 7 for a separate Solvents Study). Thus, only about
10% of the facilities that were sent preliminary questionnaires used
significant amounts of these chemicals as solvents. As described in
today's document in response to other comments, this screening removed
facilities that did not use the chemical as a solvent (as defined by
EPA), and small volume users. For a more detailed description of this
screening and evaluation see, please refer to section III.A in the
Response to Comment Document for this rulemaking.
The results of this final questionnaire showed that 4 out of the 14
chemicals in this listing determination were not
[[Page 64379]]
used as solvents and that 10 of the 14 chemicals were used a solvents
to varying degrees. The industry sectors listed by SIC code by the
commenter are ones which typically do not use any of the 14 chemicals
as solvents and, thus, did not yield data to be considered in
evaluating plausible management scenarios. Further, as discussed
earlier in this section, all other indications from the Agency's survey
show that the amounts of solvent use EPA found were generally
comparable to the solvent use found in other references. The volume of
solvent use found by the Agency is also consistent with what the Agency
knows about the likely technical usefulness of these chemicals as
solvents. A limited set of industries exists in which these chemicals
are used as solvents, as discovered through standard reference sources.
The commenter presented a plethora of small companies on the SIC
code list that operate on lower margins. The Agency believes that these
companies are not likely to use these higher cost chemicals for generic
solvent use processes. The Agency believes that if any of these
chemicals had been used as solvents in other industries, as the
commenter postulates, the Agency would have found this information
during its data collection. The facilities surveyed by the Agency share
many processes with the large number of smaller facilities in the lists
presented by the commenters (equipment cleaning, electroplating, etc.).
However, the chemicals at issue are rarely, if ever, used as solvents
in those processes in the facilities found by the Agency.
Also, the Agency recognizes that the commenter cites a greater
number of facilities within each SIC code than the number to which EPA
has sent questionnaires. These facility numbers are obtained from a
data base (Dun & Bradstreet) that is not linked to chemical use. Many
of the addresses represent corporate headquarters, not facilities that
use or generate hazardous waste, and a single facility may have more
than one Dun & Bradstreet number. Therefore, EPA believes that the
number of facilities reported within each SIC code based on this data
is exaggerated.
The commenter cites 2-methoxyethanol acetate and methyl chloride as
examples, stating that ``EPA identified seven industrial sectors
potentially using 2-MEA, but only three facilities using the solvent
received the final questionnaire.'' As presented in the background
document, 14 facilities received the full questionnaire based on their
response to the preliminary questionnaire. However, based on their
response to the full Survey, 11 of these 14 facilities discontinued use
of 2-MEA or did not use it in a manner that met the regulatory
definition of solvent use. Only two industries reported using 2-MEA in
1994 that met the definition of solvent use. The commenter further
states ``In the case of methyl chloride, EPA identified eight SIC codes
potentially using the solvent, while only seven facilities received the
final questionnaire.'' As presented in the background document, 32
facilities received the full questionnaire based on their response to
the preliminary questionnaire. However, based on their response to the
preliminary questionnaire, 24 facilities were TSDs, and as a result the
chemical consumption reported could not be linked to solvent use. Other
facilities did not use methyl chloride in a manner that met the
definition of solvent use, or used extremely small volumes (less than 1
kg) that generated wastes with no methyl chloride. Thus, this left only
four facilities that reported solvent use of methyl chloride in two
industries, and essentially all of this use was in the synthetic rubber
manufacturing.
One commenter stated that EPA chose to review chemical abstracts
for only a four-year period, and for other solvents limited the search
to a 10-year period. Therefore, older uses of the solvents would not
have been identified through the literature search. The commenter also
states that newer or less studied solvent uses would not appear in the
public literature. The commenter disagrees with the Agency's assertion
that few, if any, solvent uses were missed using this method.
In response, the Agency does not believe that searching Chemical
Abstracts for an unlimited time period for all 14 solvents is
justified. If a process was developed more than ten years ago and is
still in use today, it would appear in more recent Chemical Abstracts
or be reflected in alternative data sources, such as Effluent
Limitations Guidelines or the SRI Chemical Engineering Handbook.
Furthermore, the further back the search is conducted, the more
unlikely that the use identified will still be employed today. Newer
solvent uses, if confined to small scale laboratory use, would not
change the solvent use universe significantly and would be reported as
laboratory waste (and managed accordingly, most likely as a hazardous
waste because spent solvents exhibit a Characteristic or contain listed
wastes). Once such a process enters large-scale commercial use,
reporting generally appears on some standard database or literature
source that the Agency would find. The probability that a solvent use
would, in one year, not exist and then appear in large scale is
extremely low. Small volume solvent uses of these chemicals are not
critical to EPA's evaluation, because any risks from larger volumes
usage (and corresponding larger loadings in wastes) are likely to be of
greater concern. Most of the companies that would conduct the types of
research and development to find new uses are generally reporters to
databases like the TRI, and as such, would report any significant uses
of these solvents.
The commenter also stated that some chemicals, such as
cyclohexanol, furfural, and isophorone, are not reported under TRI. For
the remaining solvents, TRI reporting is not required when chemicals
are ``otherwise used'' in quantities of 10,000 pounds or less
(equivalent to 4,540 kg or less). The commenter argued that substantial
quantities of the solvents can be used and not reported under TRI.
In response, in cases of the three chemicals for which the TRI data
base was inadequate, the Agency relied on other sources more heavily.
In fact, the TRI was only one source for all chemicals in the listing
determination, even those covered by TRI. Because the Agency was aware
that these chemicals were not required to be reported pursuant to TRI
at the time of the solvent use industry characterization, the Agency
relied on additional sources cited in the Listing Background Document.
Through literature searches, potential solvent uses were identified in
several SIC codes for cyclohexanol, furfural and isophorone.
Moreover, since the questionnaire data were collected, the Agency
added cyclohexanol to the TRI. Analysis of TRI chemical use data on
cyclohexanol confirms the Agency's literature search and determination
of the universe of users of this chemical as a solvent. While 24
facilities reported cyclohexanol manufacturing processes in the TRI,
only one facility reported the ``otherwise use'' category of
cyclohexanol that could potentially be solvent use. Thus, the TRI data
show that the Agency might have sent out only one additional
preliminary questionnaire (EPA received 37 responses to preliminary
questionnaires for cyclohexanol). Further investigation by EPA revealed
that cyclohexanol was not used as a solvent at this one site. This new
information substantiates EPA's original findings that there are no
other large users of cyclohexanol as a solvent. See section III of the
Response to Comments Document in the docket for details of the new TRI
information.
[[Page 64380]]
The commenter argued that many of the solvent uses EPA did identify
involve extremely high concentrations of the chemicals, up to and
including pure solvent. These pure solvent uses can generate wastes in
quantities 100 times larger with concentrations of 1%, still
significantly in excess of concentrations that may pose a substantial
risk to human health or the environment.
The Agency disagrees with the commenter that the risks of concern
were not analyzed. In fact, the Agency's modeling considered
environmental loadings of these chemicals resulting from solvent uses
ranging from 100 percent to the part-per-million (ppm) level. The
Agency evaluated potential releases of high percentage solvent uses
that lead to greater loadings than would result from a one percent
level in the waste. Modeling of these chemical releases under high end
exposure conditions did not result in risks of concern.
In response to the commenter's concerns that small volume users
might generate wastes of concern, perhaps due to different management
practices, the Agency examined the data in hand from the Survey for
such users. Facilities that received Surveys due to significant use of
some solvents (>1,200 kg/yr), also used other solvents in lower volumes
in some cases. Thus, the Agency has data on wastes from facilities that
used small volumes of solvents, (see Listing Background Document,
Appendix I). EPA reviewed the management practices for wastes generated
by these smaller volume uses to see if any differences were evident.
For all 10 solvents, EPA found a total of 73 wastes that were generated
from solvent uses below 1,200 kg. The Survey data show that these were
managed in ways that were very similar to practices reported for larger
volume uses. Of these 73 wastes, 69 were incinerated or otherwise
thermally treated (nearly all were classified as hazardous because they
exhibited a hazardous Characteristic, or due to the presence of other
listed hazardous waste), three wastewaters were treated in tanks, and
one wastewater was treated in a surface impoundment (the chemical in
the impoundment, acetonitrile, was evaluated through modeling).
Furthermore, 67 of the 73 wastes reflected solvent use at
concentrations of 50-100%, i.e., many of these wastes were generated
from use of solvents at high concentration. None of these wastes from
small volume users present any special risk, because risk analyses
using larger loadings going to these management practices found no
significant risks. Therefore, the existing data support EPA's belief
that wastes from small volume users are not of any special concern.
Furthermore, these wastes are nearly all handled as hazardous, which is
also consistent with the general pattern found for other larger volume
wastes.
Two commenters stated that they agreed with EPA's decision to limit
the solvents listing investigation to facilities that use a combined
total of 1,200 kilograms or more per year of all chemicals of concern
used as solvents because the commenters feel that this level represents
a reasonable characterization of the universe of solvent users. One of
these commenters requested clarification to ensure this approach would
not be misconstrued by hazardous waste generators when determining
their generator category. In response, the Agency is confirming that
the cutoff categories used by the Agency in this listing determination
are not to be construed by any actual or potential hazardous waste
generators to be a means of determining waste generator categories.
Furthermore, EPA did consider solvent uses below the 1,200 kg threshold
as noted above, however, the Agency found that such small quantity use
is highly unlikely to present risks of concern when compared to the
risks from larger users.
However, another commenter stated that EPA's rationale for deleting
facilities using 1,200 kg or less of solvent in 1992 was that only
large quantity solvent users could be expected to have treatment,
storage, and disposal (TSD) units on-site, and that many of the solvent
uses are peculiar to large companies. The commenter stated that this
limitation in the data collection introduces bias against solvent
generators relying upon commercial services, including offsite
nonhazardous landfills, for their waste management needs. The commenter
then argued that the Agency cannot assume offsite disposal in a
nonhazardous waste landfill is rarely practiced when EPA intentionally
excluded those facilities most likely to use such facilities by not
surveying smaller volume users.
The reasoning cited by the commenter is taken out of context and
does not reflect EPA's rationale. EPA did not decide to eliminate small
volume users because they would not have on-site treatment
capabilities. Rather, EPA determined that the burden of completing a
complex, 100-plus page questionnaire would not be commensurate with the
value of the information EPA would receive. EPA would not gain useful
information from small users because many of these facilities, if they
use these chemicals as solvents at all, would present low risks
compared to larger solvent users. Furthermore, as noted above, EPA did,
in fact, capture small users of solvents in the full Survey, and found
no special management or risk concerns that were not reflected in it
evaluation of larger solvent users.
Facilities are likely to use on-site as well as off-site waste
management practices, and sometimes a combination of the two. This is
evidenced in responses to the 3007 Survey, wherein respondents
indicated that both on-site and off-site practices were employed. The
3007 Survey has captured numerous facilities that use commercial
services. Based on the results of the Survey, 62 percent of the
wastestreams are managed in commercial offsite treatment or disposal
units. As such, the Agency does not believe there is any significant
bias in its Survey.
In addition, EPA points out that the vast majority of small solvent
users eliminated by EPA reported using amounts well below the 1,200 kg
threshold. In fact more than 90% of those eliminated reported used less
than 120 kg total for all of the solvents studied. EPA found that uses
of such small volumes typically were reported for laboratory uses, are
difficult to verify, and may be reported as solvent use if laboratory
uses are not known. The 1,200 kg/yr cutoff is an appropriate surrogate
for identifying facilities that may potentially generate large amounts
of hazardous waste or waste with high solvent loadings. EPA believes
the facilities with larger solvent uses would be most likely to provide
useful data through the questionnaire, i.e., data based on verifiable
solvent use that could then be used in developing risk assessments.
One commenter argued that solvent use fluctuates from year to year,
thus uses below 1,200 kg could increase dramatically in the future due
to process changes, increases in production, or solvent substitutions.
The commenter went on to state that use volumes for some solvents
reported in the final questionnaire for 1993 were higher than the rates
reported for the same facilities in the preliminary questionnaire for
the prior year. The commenter stated that EPA fails to appreciate the
consequence of these fluctuations and substantial changes can be
expected from year to year, e.g., a facility using less than 1,200 kg
of solvent one year may use more than that amount the next year. The
commenter concludes that EPA lacks an objective basis for simply
assuming the data it collected is fully dispositive with
[[Page 64381]]
respect to future solvent uses and management practices.
EPA believes that the data collected provides a reasonable bases
for decision-making. The purpose of the preliminary questionnaire was
to capture what occurs at the facilities surveyed during a typical
year. As was expected, some facilities' solvent use consumption
decreased between the two years and other facilities' solvent
consumption increased between the two years. The Agency does not expect
solvent consumptions to be identical from year-to-year, but has no data
to indicate that 1993 is an atypical year. Even if the specific
facilities meeting the cutoff varied from year to year, EPA believes
the data gathered from facilities studied provide a representative
database. The Agency used the most recent data when determining the
1,200 kg cutoff for those facilities receiving the full questionnaire.
EPA considered whether or not solvent management practices were
likely to change in the future from those reported in the 3007 Survey.
The Agency determined that there was no reason to believe that they
would, regardless of the volume fluctuation. In the case of
wastewaters, EPA has no reason to believe that a facility would convert
from a tank-based system to a surface impoundment given the capital
investment and liability issues associated with land-based treatment,
particularly when facilities do not have the physical space for a
surface impoundment or have closed surface impoundments in favor of
tank-based systems. For nonwastewaters, EPA has no reason to believe
that a facility would switch from the thermal treatment of high organic
wastes to disposal in a nonhazardous landfill due to the BTU value and
the liability issues associated with land-based disposal.
The Agency cannot accurately predict with specificity future uses
of the fourteen chemicals, nor is it reasonable for EPA to regulate
solvent waste based on some purely hypothetical future use. While the
solvent consumption may change over time for some facilities, such
fluctuations are unlikely to significantly affect EPA's current risk
conclusions for several reasons. First, in its risk analyses EPA used
high-end or maximum solvent loadings to project potential risks. Thus,
EPA's evaluation is not likely to change due to some volume use
fluctuations. In addition, for most of these solvents (and specifically
for three noted by the commenter, acetonitrile, 2-methoxyethanol
acetate, and isophorone), the vast majority of wastes are regulated as
hazardous due to the hazardous waste characteristics (see 40 CFR
261.20-261.24) or mixing with other listed wastes. Thus, any increase
in volume use would result perhaps in somewhat higher solvent
quantities reaching wastes that would be already regulated and thus
unlikely to pose significant risk. Therefore, while EPA agrees that its
Survey is more-or-less a ``snapshot'' of waste generation data, the
Agency continues to believe that such an approach has yielded data that
are representative, and is a reasonable way to assess potential risks.
The commenter also stated that EPA excluded any laboratory uses of
the solvents from the universe of facilities receiving the preliminary
questionnaire, notwithstanding the Agency's observation that ``lab
use'' of chemicals was not restricted to small volumes.
The Agency did not exclude laboratory uses of solvent from the
universe of facilities. The Agency was precluded from sending a 3007
Survey to all laboratories due to the sheer number of labs that exist
in the United States, approximately 183,000 according to an estimate by
EPA. (For details please refer to the Response to Comments Document).
Many of these laboratories are small, comprising research labs
(12,500), medical laboratories (22,700), and university labs (108,000),
as well as small analytical labs (40,000). The resources necessary to
complete a RCRA 3007 questionnaire would be beyond the means of many of
these small businesses as organizations. Nonetheless, the Agency
captured the solvent uses and management practices of numerous (32)
captive on-site laboratories of facilities who received the 3007
Survey. In doing so, the Agency captured large research, QA/QC, and
analytical laboratories that operate at the same or larger scale as the
small labs not surveyed. Approximately 38% of the laboratories captured
were small laboratories (i.e., using <1,200 kg of solvent use).
The Agency found that in industrial facilities, the proportion of
laboratory use of a solvent compared with the chemical process use is
about 1% or less. After consulting with the American Chemical Society,
college and university hazardous waste managers, standard references,
and OSHA guidelines, the Agency determined that laboratory wastes are
managed as hazardous because they are usually mixed with other
hazardous wastes, often with acutely hazardous wastes. In addition,
with the exception of acetonitrile (which has specialized uses in
laboratories as a solvent for high pressure liquid chromatography, or
HPLC), the reported use of any of these chemicals is suspect, and is
attributable to facilities reporting ``solvent use'' in the
questionnaires as a precautionary measure. Few of the chemicals under
examination are likely to find extensive use as solvents in the
laboratory. For example, very few of the standard laboratory test
methods specified by EPA call for use of these chemicals as solvents.
For a complete summary of the laboratory use of solvents please refer
to the Response to Comments Document.
2. Engineering Site Visit Reports
One commenter stated that the engineering site visits were
superficial and did not encompass a thorough review of waste
management, solvent waste characteristics, and potential environmental
releases or damage from waste handling. The commenter acknowledged that
EPA's objective for the site visits was simply to determine if a
facility should be sent a full questionnaire, and to educate the
facility on the solvent listing process, but stated that this seems
like a waste of effort, given that more valuable information could have
been obtained from the site visits regarding waste properties, handling
and environmental damages.
The commenter also noted that none of the visits involved any
sampling efforts. No analytical or characterization data are presented
on the concentrations of solvent constituents in the waste streams
observed at the industrial sites visited. The visits were typically two
hours, with anywhere from 0-60 minutes spent actually touring the
facility. One site visit was conducted from a tour van and was strictly
a ``windshield audit,'' and two were strictly conference room audits.
The reports did not investigate, evaluate, or address any historical
spills, releases to groundwater or surface water, or any other
environmental damage from use of the solvent or handling of the wastes.
These comments misconstrue the reasons EPA conducted the site
visits and the information that could practically be developed from
them. The purpose of the site visits was to familiarize the Agency with
the multitude of processes and industries potentially subject to the
investigation through ``first person'' experience rather than
``textbook'' learning. The Agency disagrees that the Engineering Site
Visits were superficial given their purpose of site familiarity, not
data collection. The Agency points the commenter to the engineering
site visits reports that each state EPA's objectives in undertaking the
site visit--of which those cited by the commenter are but two. The site
visits were performed to
[[Page 64382]]
obtain a first hand understanding of solvent utilization and also to
develop a working relationship with the industries. Moreover, the site
visits served as an outreach mechanism for EPA to interact with
industry and inform potentially affected industries of the
investigation. Site visits afforded EPA staff an opportunity to become
familiar with processes used in specific industries, field test the
questionnaire, and assess ongoing pollution prevention activities.
EPA obtained the ``valuable information'' cited by the commenter in
a more comprehensive way through the questionnaires. EPA collected data
on waste properties and management practices through the 3007 Survey,
which contains detailed, site-specific information from 156 facilities.
It would not be practical for EPA to visit all sites to gather detailed
information on solvent use. Therefore, EPA's reliance on the 3007
Survey is eminently reasonable for collecting information on waste
characterization data, release, and waste management practices. Visits
conducted following the receipt of RCRA 3007 Questionnaires helped EPA
to better understand the type of processes used in target industries
and the data provided by respondents, and also provided confirmation of
the data provided. The Agency was able to focus on larger scale users
and specific processes up-close, based on the information reported in
the 3007 Survey.
As discussed in detail in the Response to Comments Document, tours
of the facilities lasted as little as 1.5 hours and as much as 3.5
hours, with a minimum of 30 minutes and a maximum of more than 2 hours
spent on tour and/or on the plant floor. Information related to spills,
releases and other environmental damage was requested in the 3007
questionnaire and collection of this type of information was not the
focus of these visits. The Agency takes issue with the commenter's
characterization of the visits as ``windshield audits.'' None of the
site visits were mere tours from a van. The Agency personnel witnessed
many operations on a site and were able to walk around the facility.
The commenter also mischaracterized several other details of individual
site visit reports. The Agency has corrected these misconceptions in
the Response to Comments document and provided clarification to clear
up any confusion, as necessary. For more detail on the sampling issue,
please refer to section IV.B.2 of today's document.
B. Methodology
1. Definition of ``Solvent''
One commenter objected to the Agency's characterization of solvent
use as too limiting, stating that solvents contained in paints,
coatings, dyes, fuels, etc. are still mobilizing agents, and that they
unleash the same environmental impact when these products are spilled
or released. The commenter also points out that being able to
solubilize or mobilize other constituents in a formulation still meets
the Agency's definition of solvent use.
The Agency disagrees, and notes a long-standing policy of treating
these cases differently. The discussion of the scope of the solvent
listings and the applicable definitions appears in section I.B, above.
As noted there, process wastes where solvents were used as reactants or
ingredients in the formulation of commercial chemical products are not
covered by the listing. The products themselves also are not covered.
The commercial formulations in which solvents are often ingredients are
generally products that are not wastes under RCRA. Where these products
are not in some way already regulated, the Agency could examine these
materials if they become wastes and if deemed necessary. However, with
a backlog of listing determinations to complete under court-ordered
deadlines, the Agency has focused its current efforts on those
determinations required by law. The Agency is under direction from
Congress to consider listing wastes from ``solvents'' and that
direction has been incorporated into the Consent Decree. Thus, the
Agency has focused its resources on the rather narrow set of risks
described in this Federal Register document and the rulemaking record
for this decision.
2. Lack of Sampling and Analysis
Two commenters objected that EPA performed no sampling and analysis
of these waste streams. One commenter stated it is impossible for EPA
to come to any listing determination without some independent sampling
and characterization of these wastes. Useful characterization data
could have been obtained by sampling wastes from a subset of the 156
respondents representative of all the SIC codes using the wastes,
according to this commenter.
EPA does not agree that it would obtain useful information from
independent sampling of the solvent wastes. The solvents listing
determination covers a number of industries using different solvents
for different purposes and in different ways. The greatest challenge
would be in collecting a sufficient number of samples to characterize
each of these uses. Assuming that EPA were to sample all 10 solvents,
obtain both a wastewater and a nonwastewater sample, and gather samples
from the industries using the solvents (at an estimate of three
industries on average per solvent), the baseline number of samples
required would be 60. In addition to baseline samples, to conduct a
valid sampling exercise the Agency also would need to sample for
variability, that is, the Agency would take samples at several
locations within a single facility and would take samples at several
facilities within an industry group using the same solvent. Assuming
that an additional two samples are taken within the same facility, and
then an additional two facilities are visited, the total number of
required samples reaches 540. This number still might not allow EPA to
fully characterize solvent wastes. Thus, the Agency would be spending
scarce resources on a massive sampling effort, when the data need could
be more efficiently obtained by methods other than independent
sampling. While EPA could attempt a more limited sampling approach, the
result would not be likely to provide a sound basis for making listing
decisions.
By definition, the concentration of the solvent must be relatively
high before use, and this would allow use of mass loadings in
calculating maximum waste levels, as needed. The Agency felt that it
could rely on the questionnaire data, and no information has been
submitted in comments to show that sampling and analysis was needed to
confirm the concentrations in the solvent wastes reported. The
facilities provided ranges of concentration where concentrations within
a waste stream varied. When data were reported as ranges, the Agency
used the high end of concentration ranges as a conservative approach in
its risk assessment.
The Agency does not have reason to believe that the solvent
concentrations reported are underestimated. In many instances copies of
laboratory data showing the solvent concentration(s) in a sampled
residual were provided with the respondents' 3007 survey. The reported
data seem reasonable and correspond with observations of residual
streams during Engineering Site Visits. The solvent concentrations and
residual volumes were further substantiated through mass balances
performed on the solvent use processes by reviewing the 3007 survey
responses (see section III.B of the Response to Comments Document). EPA
evaluated the data contained in the 3007 Survey
[[Page 64383]]
responses for any inconsistencies or missing residuals. If any
inconsistencies or missing residuals were found, a follow up phone call
was made to the appropriate facility for additional information. Where
applicable, this additional information can be found in the docket
along with the 3007 Survey Responses. Therefore, the Agency feels
comfortable that it can rely on the reported data to adequately
characterize risk.
EPA has used 3007 Survey data extensively in the past in making
listing determinations. In this case, each survey was signed by the
responsible party to indicate that the information reported is
accurate. The Agency does not have reason to believe that the
facilities would falsify or omit any of their data in light of the
substantial penalties for submitting false information. In instances
where concentrations were unclear or unreported, telephone contact was
made with the facility.
Two commenters stated that EPA is required to consider the presence
of any hazardous constituents, not just the solvent itself, because
other hazardous constituents may be present in the waste due to
impurities, other chemicals used in the same processes or managed in
the same equipment as the solvents, and chemical reactions occurring in
such processes or equipment.
EPA does not agree that the Agency is required to consider other
constituents present in the wastes examined. Indeed, due to the extreme
variability of these other constituents in the solvent wastes across
industries, EPA would undoubtedly find it impossible to categorize
these wastes under 40 CFR 261.11(b) if it considered the other
constituents. The solvent uses found for acetonitrile illustrate this
problem graphically. Acetonitrile is used as a solvent in various
industries, including pharmaceuticals, petrochemicals, photographic
chemicals, and other chemical manufacturers (see the Listing Background
Document, section 4.0). The actual uses of acetonitrile also are
variable, and include uses as a reaction medium for the synthesis of
numerous different chemicals, and as chromatographic eluent for
analytical or preparative separation of various chemicals from
different impurities. Wastes resulting from such widely varying
processes across different industries cannot be expected to have
consistent waste constituents, except for the solvent itself.
As the commenter pointed out, other constituents could originate
from various sources in the use of a solvent. Thus, other constituents
are dependent on other solvents used, the specific solvent use, other
processes carried out at a facility, other wastes that may be generated
from other processes onsite, etc. Because of the wide variability in
waste constituents that might arise in wastes from use of the solvents,
the Agency focused on the solvent chemical itself. Other constituents
may vary widely for different industries and solvent uses; thus, the
Agency believes the only practical approach to evaluating such wastes
for potential listing is to consider the risk posed by the solvent
chemicals under examination.
The language in the existing F-listed solvents illustrates EPA's
special concern with the solvents themselves in defining the scope of
the listings; the listings are applicable only to wastes derived from
the use of the solvents at levels of ten percent or more. In the case
of the current solvents rulemaking, the Agency evaluated the common set
of chemicals, i.e, the 14 solvents of concern. The Agency's assessment
of these 14 solvents shows no risk to human health or the environment
from these wastes, as discussed in detail elsewhere in this document.
3. Consistency of Methodology With Other Listing Determinations
One commenter asserted that, contrary to EPA's claim, the listing
determinations in today's rule were based on scenarios that are
different from those EPA used in both the proposed Dyes and Pigments
listing determination (59 FR 66072, Dec. 22, 1994) and the proposed
Petroleum Refining Process waste listing determination (60 FR 57747,
Nov. 20, 1995). The commenter stated that in the Dyes and Pigments
proposal, EPA used plausible mismanagement scenarios of disposal in
unlined municipal landfills and on-site monofills, in addition to other
plausible scenarios (wastewater treatment tanks, industrial boilers).
The commenter stated that in the Petroleum Refining Waste determination
EPA also considered plausible mismanagement scenarios, including
disposal in on-site and off-site Subtitle D landfills. The commenter
argued that EPA did not follow the policy used in the Dyes and Pigments
and Petroleum Refining rules in the proposed solvent listing because
EPA did not consider mismanagement scenarios that reasonably could be
employed, particularly land disposal in unlined landfills. The
commenter stated that there is nothing that prevents a solvent waste
generator from land disposing the solvent waste, and substantial
evidence of land disposal practices was found in the docket to the
proposed solvent rule.
In response, EPA disagrees that the methods for determining
plausible management scenarios in this rule is inconsistent with either
the proposed Dyes and Pigments listing or the Petroleum listing. In
both cases, EPA used appropriate evidence to evaluate current
conditions and to project plausible future scenarios. The Agency does
not presume unlikely worst cases or hypothesize scenarios that are not
likely in the interests of avoiding listing decisions that would not
result in incremental benefits to public health or the environment. See
Dithiocarbamate Task Force v. EPA, 98 F.3d 1394, 1401 (D.C. Cir. 1996).
With respect to the Dyes and Pigments proposal, management in
unlined municipal landfills and on-site monofills was reported in the
3007 Survey for certain wastes. EPA found that nearly all dye and
pigment waste sludges/solids studied had, in fact, been disposed in
unlined municipal landfills. Thus, the Agency determined that placement
in an unlined landfill was plausible for most dye and pigment
wastestreams.
However, EPA did not consider disposal in landfills plausible for
all Dyes and Pigment wastes, and considered the specific facts for each
waste. For example, EPA proposed not to list one category of waste,
wastewater treatment sludges from the production of triarlymethane
pigments using aniline as a feedstock, despite risks that might arise
if the waste were send to a landfill. For this waste category, EPA
determined a landfill was not plausible management (see 59 FR 66096).
This was because the current management practice was blending with fuel
for combustion, and EPA decided that the high organic content and fuel
value of the waste made it implausible that landfill disposal would
occur. This is entirely consistent with EPA's approach in today's rule
for a similar waste derived from use of acetonitrile as a solvent. As
described in the specific section on acetonitrile (section IV.D3), EPA
does not view risks that might arise from landfill disposal as
significant because such disposal is unlikely given the current
practice of fuel blending and the confirmed fuel value of the material.
The commenter is also incorrect in asserting that the approach used
in today's rule is inconsistent with that used in the Petroleum
Refining proposal. In that proposal the Agency evaluated landfill
disposal for many of the wastes examined, because, in fact, this
practice was reported to occur for those wastes. Contrary to what the
commenter implied, EPA did not project landfill disposal in the
Petroleum
[[Page 64384]]
Refining proposal as plausible for wastes that had no evidence of such
disposal.
The commenter also stated that the Agency violated its own risk
assessment criteria as presented in the listing determination for the
proposed Dyes and Pigments wastes (see 59 FR 66076). The commenter
pointed out that EPA states in the preamble that it is the Agency
policy that a high-end hazard quotient above 1 represents a risk level
for presumptive listing, and a high-end hazard quotient above 2 is a
definite basis to list. The commenter argued that, if EPA applies this
policy to the solvent listing determination, at a minimum both
acetonitrile and 2-methoxyethanol have hazard quotients exceeding this
criteria (HQ of 200 and 16, respectively), and should have been listed.
EPA disagrees that its decisions in today's listing are
inconsistent with its listing policy. As the Agency explained in the
proposed rule, EPA's risk assessment for acetonitrile indicated HQs
below one at the bounding level for incineration and at the high-end
for wastewater treatment tanks and for open storage tanks. EPA's risk
assessment for 2-methoxyethanol indicated HQs below one in bounding
analyses for wastewater treatment tanks and incineration and no risk
for the storage tank scenario. The HQs cited by the commenter were
reported as part of an intermediate stage of the analysis, as reported
in the background document for the proposed rule, specifically,
Sec. 5.7 of the Assessment of Risks from the Management of Used
Solvents. This intermediate stage was used to decide if further
evaluation was necessary. Because possible risks of concern were found,
EPA proceeded to a third phase of assessment. After consideration of
the fact that nearly all of the wastes evaluated in the intermediate
analyses were already hazardous, EPA's assessments for these scenarios
indicated risks below levels of concern for the remaining nonhazardous
waste streams (see Supplemental Risk Assessment). These multi-phase
assessments are discussed further in response to specific comments on
acetonitrile in section IV.D.3 of today's document.
4. Plausible Mismanagement Scenarios
Two commenters stated that EPA relied on incomplete data provided
in the RCRA 3007 Questionnaires to identify actual management, and
disregarded standard potential mismanagement scenarios based on an
incorrect assumption that solvent waste management will not change over
time. According to these two commenters, a valid solvent listing
determination must also consider improper disposal in unlined
landfills, impoundments, waste piles, land treatment units, and long
term accumulation, which EPA overlooked. One of the commenters went on
to state that the Agency's listing policy requires the presumption of
land disposal in unlined landfills and surface impoundments,
particularly in the case of solvents, where EPA's questionnaire data
present a partial and misleading snapshot of solvent use due to
limitations in the data collection methodology. This commenter also
argued that due to the limitations of the data collection, EPA cannot
claim that the specialized or limited uses of the solvents lead to a
complete characterization of solvent users or solvent waste management
practices. The commenter concluded that EPA's decision not to list
these solvents is invalid and contrary to the criteria enumerated in 40
CFR 261.11.
The Agency disagrees with the two commenters. The data collected
show that the management practices of most concern to the commenters
(landfills and surface impoundments) are not widely used. Where land-
based disposal was reported in the 3007 Survey, the Agency considered
whether the waste is capable of posing a substantial present or
potential hazard to human health or the environment. For landfills, EPA
found that modeling was not necessary because solvent loadings were
very low. The few cases of surface impoundment use were fully evaluated
via modeling and were found to present no significant risk.
EPA relied on management practices reported in response to the 3007
Surveys, and EPA evaluated the potential risks associated with those
management practices that are used or likely to be used. As the Agency
has explained in prior responses, EPA could and did target the
facilities and industries actually using these chemicals as solvents.
As a result, the Agency identified the largest users of these chemicals
as solvents. EPA has responded in detail to comments regarding the
adequacy of the characterization of solvent waste generators earlier in
today's document (see section IV.A.1).
The solvent wastes reported from the Survey fell into several
classes: high concentration organic liquids or solids, treatment
residuals (wastewater treatment sludge, incinerator ash), and
wastewaters. The high content organic nonwastewaters were sent to
thermal treatment in incinerators, boilers, or fuel blenders, and in
some cases recovered via distillation for reuse. The vast majority of
these wastes were managed as hazardous waste, because they exhibit a
characteristic (primarily ignitability), or they are generated as a
waste mixture with solvents that are already listed as hazardous.
From the data available, EPA evaluated the potential for risks to
arise from disposal of solids in landfills and the treatment of
wastewaters in surface impoundment. Wastes reported to go to landfills
were typically treatment residuals that contained negligible amounts of
solvents. For the 10 solvents examined (the remaining 4 on the original
list of 14 had essentially no solvent use), no landfill disposal was
reported for six of these solvents. In fact, of the total 435 solvent
wastes reported for the 10 chemicals, only 5 were reported to go to
nonhazardous waste landfills. In the proposed rule and the Listing
Background Document, EPA discussed why the few cases of landfill
disposal reported for specific solvents (acetonitrile waste, methyl
chloride, cumene, and cyclohexanol) were not of concern. This was
principally because the solvent loadings in these wastes were very low.
In response to comments, EPA further considered one waste that was
reported to be disposed in a hazardous landfill. However as discussed
in the specific section in today's rule on acetonitrile, the waste is
no longer going to any type of landfill due to its thermal value.
The Survey data show that wastes sent to landfills contained
negligible amounts of solvent; landfilling of wastes with high solvent
concentration was not reported. Thus, given these results, and the fact
that nonwastewaters with high solvent content are generally hazardous
and could not be placed in even a Subtitle C landfill without further
treatment, EPA had no reasonable basis to conclude that disposal of
spent solvent wastes in landfills poses a risk of concern.
Similarly, treatment of wastewaters in surface impoundments was
rare for the solvent wastes examined (the vast majority were treated in
tanks). Of all the wastes reported (435), only 10 were reported to
undergo treatment in surface impoundments. The solvent loadings for six
of these (from solvent use of acetonitrile and cumene) were low and
clearly present no risk after dilution/treatment in a wastewater
treatment system. The others were larger volume wastewaters that arose
from the specialized use of three different solvents: methyl chloride,
phenol, and furfural. With the reported solvent loadings available, EPA
examined these special cases closely, and completed further modeling in
response to
[[Page 64385]]
comments (see section IV.C.1 on surface impoundment modeling).
Concerning storage in waste piles and land treatment, EPA found no
cases where such management practices were reported for any of the
wastes examined. The lack of waste pile storage is not surprising given
the nature of most wastes that are accumulated, i.e., organic liquids
and aqueous wastewaters, which are stored in tanks. Further, many of
these wastes are already hazardous, and are therefore kept in storage
containers that meet stringent RCRA regulations. Other solids were
either relatively low volume wastes, for which a pile is not needed, or
wastewater treatment residuals, which have no appreciable solvent
content, as noted above. The practice of land treatment is a special
practice that is relatively rare, and as EPA has noted in the past (see
Dyes and Pigments rule, 59 FR 66074), such practices would be
considered plausible only when information indicates that the practice
is in use, or likely to be used in the future.
The Agency determined that the actual management practices
represent the plausible management practices for the specific solvent
wastes that are the subject of today's rule, because the Agency found
no reason to believe that the current management practices would change
significantly. In the case of wastewaters, EPA has no reason to believe
that a facility would convert from a tank-based system to a surface
impoundment given the capital investment and liability issues
associated with constructing and operating land-based treatment units.
The ongoing operating costs of managing wastewaters in an already
installed tank are quite small relative to the costs of constructing a
surface impoundment, or the costs of other alternatives such as sending
the wastewaters offsite. Clearly, a large majority of facilities
perceive a benefit from managing the waters in tanks, rather than
impoundments, and EPA finds no reasons to project that those facilities
would change their practices. For nonwastewaters, EPA has no reason to
believe that a facility would switch from the thermal treatment of high
organic wastes to disposal in a nonhazardous landfill due to the BTU
value and the liability issues associated with land-based disposal. In
fact, the data collected from the Survey clearly show that the use of
impoundments and landfills is rare, and such practices are not common
for these wastes. Also, as noted previously, the vast majority of
nonwastewaters are already classified as hazardous waste, and cannot be
land disposed without meeting treatment standards.
EPA believes the Survey did, in fact, collect sufficient data from
the significant solvent users, to allow a reasonable assessment of
plausible mismanagement scenarios. However, even assuming the data do
not reflect all management practices for whatever reason, the Agency
still maintains that the data available support EPA's decisions on what
constitutes plausible mismanagement. The data collected show that the
management practices of most concern to the commenters (landfills and
surface impoundments) are rarely used for these solvent wastes.
Furthermore, when these practices are used they are used for only very
dilute concentration (and low risk) solvent wastes, except for a few
special cases that were specifically considered by the Agency. The
existing data do not support the commenters' argument that other
practices must be assumed to be generally plausible for all the wastes
evaluated. Creating hypothetical waste management scenarios would have
no apparent benefit, and may lead to regulating wastes which do not
present risks.
C. Risk Assessment
This section deals with comments on the hazard and exposure
assessments conducted for the rulemaking. In response to comments, the
Agency revised the risk assessment for some management scenarios. These
updated results are presented in the following sections, along with
responses to the comments. Full details of the updated analyses are
presented in the background document for the risk assessment
(Assessment of Risks from the Management of Used Solvents: Supplemental
Risk Assessment Background Document, hereafter known as Supplemental
Risk Assessment) provided in the docket to this rule. A summary of risk
assessment results for all solvents are shown in Table 3. Comments
dealing with the volumes and concentrations of wastes used as inputs
for the risk assessment are dealt with in sections IV.A and IV.B.
1. Surface Impoundments
EPA received a variety of comments relating to the assessment of
risks from management of solvent wastewaters in surface impoundments.
One comment focused on the routes of exposure that were assessed from
the groundwater pathway from surface impoundments. The commenter
indicated that EPA's consideration of direct ingestion alone was
insufficient for assessing the risk from this pathway, and suggested
that the Agency evaluate other routes of exposure from groundwater. EPA
agrees that these additional routes of exposure should be evaluated,
and conducted additional analysis as described below.
In addition, two commenters suggested that the risk assessment
should have assumed a higher concentration level for the solvents in
these management units. The Agency used the headworks concentration (at
the beginning of the wastewater treatment process), which represents a
dilution of the solvent with other wastewaters. The high-end data on
concentrations were taken from the section 3007 survey of all
facilities, as noted in section IV.B.2, above.
EPA does not agree that higher concentrations of solvents should be
used, but rather believes that its approach described below is more
appropriate. To respond to these comments, the Agency conducted further
modeling of surface impoundments to reevaluate the risks from solvents
managed in these units. The risk reevaluation is summarized below; see
the Supplemental Risk Assessment document for a full description of the
methodology and results.
In the risk assessment for the proposed rule, EPA reviewed the
high-end waste streams going to surface impoundments. The process of
iterative risk screening rests on assessing high-end values, based on
the premise that low-end values represent lower risk. Since the high-
end waste streams did not show significant risk, EPA did not review the
impoundments further. For the current effort, EPA ensured that all
relevant factors were accounted for by modeling all the surface
impoundments receiving wastewaters with these solvents. EPA used a
standard Agency model (CHEMDAT8) to assess the steady state
concentration of solvent in these units; EPA used the precursor
(CHEMDAT7) in modeling for the proposed rule. To the extent possible,
EPA attempted to use actual influent concentrations into the
impoundments; this information was only available for one of the
impoundments (at the Exxon Baytown facility). For the other surface
impoundments, EPA used the headworks concentrations again. EPA believes
that these concentrations represent a conservative estimate of the
concentration of solvent entering the impoundment, since they do not
account for the significant pretreatment occurring (in all cases) after
the headworks, before entering the impoundment. Because of this
pretreatment, the actual solvent concentration of influent to the
[[Page 64386]]
impoundment will be much lower than the headworks concentrations that
were assumed for the modeling.
Using CHEMDAT8, EPA then modeled the resulting steady state
concentrations of the solvents in each impoundment, as well as
estimated quantities and concentrations of solvents that would be
emitted to the air. EPA assessed direct inhalation risks using these
airborne emissions from the solvent.
Risks from the groundwater pathway were assessed for all
impoundments where the groundwater was considered at risk. To assess
the risks from the groundwater pathway, EPA assumed no attenuation from
the impoundment to the leachate. EPA estimated groundwater
concentrations at a high-end receptor, and from that groundwater
pathway assessed risks of direct ingestion of the groundwater, as well
as inhalation and dermal contact risks from use of the groundwater.
This assessment used the same methodology employed by the Agency in a
recent listing (Hazardous Waste Management System; Identification and
Listing of Hazardous Waste; Petroleum Refining Process Wastes; 63 FR
42109, August 6, 1998 ) to estimate non-ingestion risks from the
groundwater pathway.
The results of the assessment for the impoundments are summarized
in Table 2. All hazard quotients represent cumulative figures for all
pathways and routes of exposure. The assessment of cumulative risk from
these routes of exposure is very conservative, in that it assumes that
receptor locations were at the maximum exposure point for direct
inhalation of airborne solvents, as well as for exposure to solvents in
groundwater. EPA also added HQs from different chemicals in the same
unit, making the highly conservative assumption that all of the
noncarcinogens threatened similar health endpoints (i.e., cause the
same type of damage to the same organs). This latter assumption is not
likely to be true, but there was no need to refine the risk analysis to
ascertain what the different endpoints might actually be, because the
summed HQs were less than one. Because those multiple conservative
assumptions were used in the analysis, the true high-end risk estimates
would actually be lower than the numbers listed under the ``High-End''
column.
Table 2.--Risk Assessment Results For Management of Solvents in Surface Impoundments \1\
----------------------------------------------------------------------------------------------------------------
Facility Solvents in unit Bounding HQ \2\ ``High-end'' HQ
------------------------------------------------------------------------------------------------------\2\-------
Tennessee Eastman.............. Acetonitrile, Phenol.. 3.30e-02........................... N/A \3\.
Exxon Baytown.................. Methyl Chloride \2\... [4.60e-06]......................... [3.50e-06].
Mobil Beaumont................. Furfural, Phenol...... 1.20e+00........................... 8.00e-01.
Lyondell....................... Cumene................ 4.10e-02........................... N/A.
Rhone-Poulenc.................. Acetonitrile.......... 6.52e-02........................... N/A.
Citgo.......................... Phenol, Furfural...... 7.40e-01........................... N/A.
----------------------------------------------------------------------------------------------------------------
\1\ Risks presented represent the total risk from concurrent exposure to air and groundwater releases, and also
the sum of risks from all solvents in the unit. The ``high-end'' risks are above a high-end due to these and
other conservative assumptions.
\2\ Risks for methyl chloride represent excess lifetime individual cancer risk .
\3\ N/A indicates high-end analysis was not done because the bounding analysis showed no risk of concern.
2. Tank-Based Management of Wastes
In the process of responding to comments comparing EPA's evaluation
of the solvent wastes in question with the results of a recent EPA
study on potential air risks (see comment below related to the Air
Characteristic Study), EPA reviewed the risk analyses conducted in the
proposed rule for management of wastes in tanks. EPA discovered that an
arithmetic error was made in the calculation of solvent emissions from
tanks. This error resulted in an underestimation of emissions for all
tank scenarios by a factor of 1,000.
EPA has therefore revised the risk estimates for tank-based
management of wastes. The analytical approach was to update the
analyses that were completed for the proposed rule, using corrected
emissions, the latest version of the emissions model (CHEMDAT8), and
current chemical and toxicological benchmark data available for some
chemicals. The analysis also refined parameter values to more closely
approach high-end analyses; nevertheless, because of multiple high-end
assumptions, all of the revised analyses are still characterized as
more conservative than true high-ends. In addition, EPA conducted a
second analysis to verify these results. This second analysis used air
dispersion data and receptor distances from EPA's Air Characteristic
Study (May, 1998). Both analyses, using the corrected source term data,
indicated that risks for all tank-based scenarios were below levels of
significant concern (see section IV.C for further discussion of listing
decisions). More details of the analyses are presented in the
Supplemental Risk Assessment Background document. The results of these
analyses are presented in Table 3.
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3. Multiple Solvents
A commenter noted that EPA failed to consider the cumulative
impacts of multiple solvents and other hazardous constituents released
via the same exposure pathways in the risk assessment. In order to
fully respond to this comment, EPA conducted an assessment of the
cumulative risks posed by exposure to multiple solvents. Inasmuch as
the listing determination is based on the solvent constituents of these
wastes, other constituents of the wastestreams were not assessed. These
risk assessment results, therefore, only apply to the solvents
themselves. In this analysis (see the Supplemental Risk Assessment for
details) EPA assessed all cumulative solvents risks where multiple
solvents were managed in one unit or in different units at a facility.
This analysis used the same assumptions as EPA's prior assessments
for the proposed rule. Wastestreams which were already classified and
managed as hazardous were not assessed, since there is little
likelihood of risk reduction through a listing determination. EPA
focused its effort on currently unregulated wastes. The
characterizations of waste management included the same conservative
parameters as in the proposed rule, modified as described above,
including the construction and operation of surface impoundments,
meteorological conditions, and the proximity of hypothetical receptors.
One particularly conservative assumption was storage of solvents in
open-topped tanks permitting maximum volatilization. This assumption of
extensive volatilization out of open-topped tanks is highly unlikely,
because the wastes were being stored pending incineration or other
thermal treatment. In addition to those factors, EPA included highly
unrealistic assumptions in assessing cumulative risk from exposure to
multiple solvents. Environmental receptors were considered to be
located at maximum exposure points relative to all management units.
EPA also added HQs from different chemicals, making the highly
conservative assumption that all of the non-carcinogens threatened
similar health endpoints (i.e., cause the same type of damage to the
same organs). This latter assumption is not likely to be true, and
overestimates risks, but there was no need to refine the risk analysis
to ascertain what the different endpoints might actually be.
Despite these assumptions, which suggested unrealistic conditions
to maximize the probability of showing risk to human health, none of
the assessed scenarios showed combined hazard indices over one. In one
facility (Exxon, Baytown), a surface impoundment showed an increased
cancer risk of 4E-06 in the high-end analysis, however, this risk was
entirely due to the single solvent methyl chloride, as shown in the
preceding section. As discussed in section IV.D, EPA has concluded that
this does not represent a significant risk, especially in light of
existing air regulations that apply to this unit.
The scientific evidence represented by this risk analysis leads EPA
to the clear conclusion that management of multiple solvents does not
pose significant incremental risk to human health in any populations.
4. Comparison With HWIR Exit Levels
A commenter argued that EPA should reconsider the risks from
acetonitrile, phenol, methyl chloride, and isophorone based on the risk
analysis presented by EPA in the proposed Hazardous Waste
Identification Rule (HWIR; 60 FR 66344, December 21, 1995). For each of
these chemicals, the HWIR analysis produced an ``exit level''
concentration, suggesting that concentrations of waste higher than the
exit level might pose unacceptable risks. The commenter notes that the
Sec. 3007 survey showed solvent wastes for each of these chemicals
being generated at higher concentrations than the HWIR exit levels. The
commenter noted that wastewaters of acetonitrile, phenol, methyl
chloride, and isophorone are generated in concentrations higher than
the HWIR exit levels for these chemicals.
The commenter's comparison between HWIR exit levels and the solvent
waste concentrations does not indicate that the solvent risks are of
concern. The purpose of the HWIR exit levels is not to assess risk from
a particular set of chemicals or a specific set of wastes. Unlike
listings, where the Agency makes a decision based on actual information
about how specific wastes are generated and managed, the HWIR levels
are intended as broad risk screens, covering a large number of possible
waste streams and waste management methods. The listing decisions for
the chemicals examined in today's rule are limited to consideration of
potential risks that arise only from the wastes generated after the
chemicals are used as solvents. Therefore, these decisions are limited
to considerations of waste characteristics and waste management
practices specific to these uses.
Because HWIR had a different purpose than this risk assessment, it
used different methodologies. HWIR evaluated five management scenarios:
aerated treatment tanks, quiescent surface impoundments, land
application units, ash monofills, and wastepiles. Only two of these
scenarios aerated treatment tanks and quiescent surface impoundments
are similar to the management scenarios modeled for the used solvents
risk assessment. Another obstacle to comparison is the waste volume
modeled. HWIR modeled a range of waste volumes, bounded by the capacity
of the waste management unit. From these volumes, HWIR calculated
levels for specific chemicals on a nationwide basis, for any use in any
industry, and made various assumptions for waste generations and
management, as noted above. In contrast, the wastestream volumes (and
constituent loadings) modeled for the solvents risk assessment were
based on actual data from the industry survey.
The Agency has not issued the HWIR in final form and is continuing
to refine the analysis; therefore, the HWIR exit levels are currently
being reviewed and revised. However, even the revised numbers, as a
screening tool, cannot be automatically used in assessing the validity
of other regulatory actions by EPA. Together, the differences in
management units and wastes modeled mean that a simple comparison of
HWIR exit level concentrations to the concentrations in modeled solvent
wastes is not meaningful.
5. Environmental Damage Incidents
Several commenters stated that the Agency screened out and ignored
damage cases prior to 1980. EPA believes that the commenters have
apparently misunderstood how the Agency evaluated the damage cases. The
Agency did not screen out and ignore damage cases prior to 1980. All
damage cases available were considered including those prior to 1980.
However, most of the damage cases found for the 14 chemicals resulted
from disposal well before 1980, before RCRA regulations were in place.
Damage cases were reviewed to direct the analysis to industries and
conditions that might show evidence of environmental damage from
improper management of used solvents that might be occurring now or may
occur in the future; the cases did not provide an exclusive or
restrictive guide. EPA evaluated a variety of legal and financial
factors that might affect plausible management, and technological
factors affecting fate and transport of hazardous constituents.
These other factors are especially important when examining the
solvent wastestreams, since almost 90% of the non-wastewaters are
already required to
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be managed as hazardous under Subtitle C. Although these constituents
may have been found at Superfund sites, it is not reasonable to suggest
that RCRA-regulated hazardous wastes could be managed today in the same
way they were managed at industrial facilities in the past. The damage
cases that were found reflect mismanagement in the past, not the
Subtitle C management (or even the likely Subtitle D management) of
these chemicals which is the norm today.
Furthermore, as described in the proposed rule, there were many
other reasons why the damage cases were not useful (see 61 FR 42326).
These reasons include: (1) EPA could not determine that any of the
contaminants of concern were used as a solvent prior to disposal; (2)
wastes at these sites were poorly defined, and the term ``solvent
wastes'' likely referred to the more widely used solvents that are
already listed; (3) many of the chemicals under study have other uses
that are more likely to be the reason for contamination; and (4) EPA
found no damage cases at sites within the industries that reported
using the solvents under study.
6. Spills, Leaks, and Overflows
One commenter stated that EPA's risk assessment did not include an
evaluation of human health and environmental risks posed by leaking
tank systems. According to this commenter, EPA argues the concentration
of solvents is ``very low'' in wastewaters, and thus assessing the
risks posed by tank leaks is not warranted. However, the commenter
argued the database identifies solvent wastewaters containing 9% 2-
methoxyethanol, 8% phenol, 200 ppm 2-EEA, 169 ppm methyl chloride, and
5,000 ppm furfural. The commenter concluded, given that no time limit
would be placed on storage if the wastes are not regulated as
hazardous, defective leaking containers and tanks are highly possible.
EPA has examined the possibility of spills from management units
such as tanks or surface impoundments. The Agency does not have the
data or the means available to accurately assess the likelihood of such
releases, the magnitude of releases, or other data that would be
necessary to assess the risk of such spills. Based on the
characteristics of these solvent waste streams, however, the Agency has
concluded that to the extent that such releases would pose risks, a
decision to list any of these wastes would not provide significant
reduction in the potential hazards from such events. The Agency bases
that conclusion on the following facts.
The vast majority (over 98%) of the volume of solvent wastes are
wastewaters in wastewater treatment units. These wastewaters are
diluted to very low concentrations of solvents, and are treated further
to even lower levels. When necessary, EPA has modeled the effects of
release of some of these solvents from impoundments and found no
significant risk to human health or the environment (see section IV.C.1
for further discussion on potential risks from impoundments). For the
specific wastewaters identified by the commenter, EPA notes that
surface impoundment scenarios were modeled for phenol, methyl chloride,
and furfural at the same or similar concentrations to those cited, and
no significant risks were found. The wastewater mentioned that contains
2-methoxyethanol is managed as hazardous in an off-site biological
treatment system, so that any releases or risks are unlikely.
Similarly, the 2-EEA waste cited is scrubber water that is classified
as hazardous, and furthermore corresponds to a total of only 0.58 kg of
EEA. Therefore, EPA does not agree that these wastes are likely to
present significant risk even under a spill scenario.
Of the nonwastewaters, almost 90% are already regulated under
Subtitle C of RCRA. Spills from the RCRA units are already covered
under contingency planning and corrective action requirements. Subpart
CC includes additional requirements for spill protection during
transfer of wastes (see 40 CFR 264.1084(j)). Therefore, EPA concludes
that spills of these wastes from tanks, which would generally be
episodic in any case and unlikely to produce long-term exposures
comparable to those considered in listing determinations, are not of
significant concern.
7. Non-Aqueous Phase Liquids (NAPLs)
In the proposed rule, even though EPA could not find scenarios that
could lead to significant releases to ground water, the Agency also
considered whether the spent solvent wastes had the potential to form
non-aqueous phase liquids (NAPLs) that might move as a separate phase
either above or below the ground water table. These NAPLs may present
special problems, especially in assessing their transport and potential
impact. However, EPA found that nearly all solvents under consideration
are miscible or very soluble in water and are not likely to form NAPLs
in groundwater. One commenter suggested that EPA re-examine the
possibility of formation of NAPLs from these solvents.
To respond to this concern, EPA has conducted further analysis on
the subject for this final rulemaking. Full details of this analysis
are in the Supplemental Risk Assessment document for this rulemaking.
Only four of the solvents are land disposed and pose a threat to the
groundwater pathway: acetonitrile, phenol, furfural, and cumene. EPA
assessed the possibility of formation of NAPLs from land disposal of
these solvents.
The first three are all highly soluble, which indicates that NAPL
formation is unlikely. EPA then assessed the likelihood of NAPL
formation from cumene, using the methodology which has been developed
for assessing NAPL probabilities at Superfund sites. Conservative
estimations of the concentrations of cumene in groundwater still fell
an order of magnitude below the threshold at which NAPL formation is a
serious possibility. Therefore, EPA concludes that there is little
likelihood of these solvents contributing to formation of NAPLs.
8. Risk Modeling Parameters
One commenter stated that the accumulation scenario modeled must
assume long term storage, not a period of under 90 days. The commenter
argued that extended on-site accumulation is a highly plausible
mismanagement scenario, given that absent RCRA controls, a generator
can accumulate such waste indefinitely. Thus, the commenter stated that
EPA's risk model should not assume a finite storage time of 90 days,
but should assume the more likely scenario of at least a two year
period of storage.
This comment is based on an incorrect assumption. The accumulation
scenario was not modeled for a period of 90 days as stated by the
commenter. For each scenario, EPA used a storage duration designed to
maximize the total risk. Modeling a longer storage time does not
necessarily increase the risk, because it implies less frequent
refilling of the tanks with new wastes. As described in the risk
assessment documentation, this storage duration time was calculated by
first generating a tank profile to yield the largest downwind
concentration at the nearest residence based on data in Hazardous Waste
Treatment, Storage, and Disposal Facilities (TSDF)--Background
Information for Proposed RCRA Air Emission Standards (referenced in the
proposal risk documentation as U.S. EPA, 1991c; p. 29, July 1996).
(This high-end tank also happened to be the most common. Therefore,
this model tank was used for all three types of estimates: bounding,
high-end, and
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central tendency.) The throughput and other parameters of this model
tank were used in combination with solvent throughputs and high-end and
central tendency concentrations to obtain solvent-specific emissions
rates. The storage duration times were then back-calculated to fit this
maximum release profile. For the bounding analysis, the modeling was so
conservative that it resulted in greater than 95 percent release of the
solvent in seven out of ten cases. Thus, a longer accumulation time, as
suggested by the commenter, would have led to lower emissions, lower
concentrations at the receptor, and thus a less conservative analysis.
9. Comparison With Results of Air Characteristic Study
EPA received a late comment suggesting that the risk analysis in
the Air Characteristic Study recently released by the Agency (May,
1998) indicated that air pathway releases from these solvents were
riskier than EPA's initial analysis had indicated. The commenter
compared concentration levels of potential concern developed for some
chemicals in the Air Characteristic Study to concentrations of the
solvents reported in the listing determination. The commenter argued
that the study showed significant inhalation risks for some of the
solvents when managed in tanks at concentrations significantly lower
than those found in the solvents data collection.
In response, EPA first notes that the purpose of the Air
Characteristic Study was to evaluate the possible need for an air
characteristic to address potential risks due to emissions from certain
waste management units. The concentrations of concern estimated in the
Study are screening values for the purpose of determining whether new
regulatory controls are needed to fill potential gaps in existing
regulations, and should be viewed in this context. The concentrations
developed in the Study cannot be automatically used in assessing the
validity of other regulatory actions by EPA, because the study uses
waste data and certain modeling assumptions in its methodology that are
different in a number of ways from the modeling assumptions and data
used in other regulatory programs, such as listing determinations. In
addition, the Study methodology is currently undergoing outside peer
review. Therefore, the screening concentrations themselves could change
pending the results of the review.
In any event, a comparison of the results reached in the Air
Characteristic Study with the results of this risk assessment confirms
that the concentrations present in these solvent wastes do not pose a
significant inhalation risk. As noted above, EPA found an error in the
risk analyses for tanks, and revised these analyses accordingly. This
was the principal reason for the apparent difference in risk estimates
between the risk assessment for the proposed analysis and the Air
Characteristic Study (see section IV.C.2). However, even with these
revisions, some apparent differences in concentration levels of concern
would remain.
These differences in concentration, however, do not necessarily
mean differences in risk. In this case, the source terms being compared
are different. The Air Characteristic Study back-calculated to
determine what loading of constituent could be safely managed in a
given management scenario. For every management scenario, the loadings
of constituent that the Air Characteristic Study concluded could be
managed safely are larger than the loadings used in this risk
assessment. The solvent constituent loading that the Air Characteristic
Study determined could be safely managed in tanks ranged from twice the
amount to millions of times the amount modeled for the solvents risk
assessment. The analyses for today's listing determination used the
solvent waste generation data (and subsequent loadings in management
units) from the Sec. 3007 Survey. The purpose of this listing is to
determine the risks that may be posed by current and plausible future
management of these specific chemicals when used as solvents,
therefore, the EPA feels that the solvents waste generation data
submitted from the 3007 survey is appropriate to use in the analysis.
To better understand the differences in risk assessment methodology
used in the Air Characteristic Study, the Agency conducted a re-
analysis of the risk from the solvent wastestreams using a modified
methodology from the Air Characteristic Study, but still using the
waste generation data and solvent loadings from the listing Survey. The
methodology was virtually the same as that used in the Air
Characteristic Study, except for some inputs that the study derived
through Monte Carlo analysis. The results of this verification analysis
showed no significant risk for any of the solvent management scenarios,
and confirm the previous results. These results appear in Table 3. More
details on these comparisons appears in the response to comments
document accompanying this rulemaking.
D. Listing Determinations
EPA received comments on various aspects of the proposed listing
determinations. Many comments on the determinations were raised
repeatedly for various wastes, and are discussed in preceding sections,
or in sections IV.D.1 and IV.D.2 below. Comments that are more specific
for individual solvent wastes are addressed in the section IV.D.3. For
complete responses to comments on these and other issues, see the
Response to Comments Document in the docket to today's rule.
1. General Comments
Six commenters support EPA's decision not to list as hazardous
waste the solvents at issue. However, one commenter disagreed with the
decision not to list these compounds because they are similar in
toxicity to the other solvents already listed as hazardous. The
commenter stated that the solvents considered in this rule may be used
by themselves, and their wastes, therefore, would not be mixed with the
wastes from the other F-listed wastes, or the manufacturer can modify
their processes to avoid using other F-listed solvents, so that their
wastes would no longer be hazardous. The commenter went on to wonder if
EPA's decision not to list these wastes was due to its ``anti-
combustion'' strategy, because the wastes would ``then be readily
excluded from combustion as a logical disposal option.''
EPA does not agree with the commenter's assertions regarding the
decisions not to list. While some of the chemicals examined in today's
rule may have toxicity similar to the solvents already listed as F-
wastes, the toxicity of a chemical alone is not a sufficient basis for
listing. EPA considers a variety of factors, including waste management
practices and all the other factors listed in 40 CFR 261.11(a)(3).
After evaluation of all factors, EPA determined that listing for these
solvent wastes was not warranted. When appropriate, EPA also evaluated
wastes that resulted from use of the solvent by itself and found no
significant risks.
Further, EPA disagrees that in the absence of a listing decision a
manufacturer would change its processes to segregate out the solvents
considered in this rule. They had that incentive from the time the
other solvents were listed in 1980 and 1986 and have either been mixing
the wastes ever since or made decisions to make new mixtures with
listed solvents. If a waste is hazardous under current regulations, due
to mixture with other listed wastes or a characteristic, the
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manufacturer already has ample incentive to modify its process to avoid
the cost of generating more hazardous waste. These manufacturers
apparently weighed the risks and benefits of mixing, or not mixing the
wastes and still pursued their mixing practices. As the Agency has
stated in today's document and in the Response to Comments Document,
many of these decisions are driven by specific process parameters, cost
effectiveness, chemical compatibility, and regulations of other
Agencies. EPA has no reason to believe they will change these practices
in the event of a final no-listing decision, considering that this
decision does not change the status quo. Thus, EPA does not agree that
a non-list decision would alter this behavior. Finally, EPA points out
that many of the wastes examined in today's rule are, in fact, treated
by combustion, typically in hazardous waste incinerators. Therefore,
the wastes are not ``readily excluded'' from combustion as result of
the no-list decisions.
2. Sufficient Regulation of Solvents
One commenter stated that EPA assigned appropriate weight to the
fact that many solvents already are hazardous, a determination that is
relevant to the Agency's assessment of plausible mismanagement
scenarios, its determination in the risk assessment that no further
risk reduction could be achieved through listing the solvents of
concern as hazardous, and its determinations regarding the relevance
and applicability of damage incidents identified. This commenter
further stated that EPA gave due consideration to the benefits accorded
by other regulatory programs. Another commenter, however, stated that
the Agency should carefully consider the benefits associated with
listing the solvent wastes that may exhibit a hazardous waste
characteristic or are sometimes co-managed with presently listed
solvent wastes. This commenter stated that there are important legal
and policy reasons for listing the solvent wastes at issue in this
rulemaking. The commenter noted that in the case of characteristic
solvent wastes, listing the respective wastes obviates the need for
testing to determine whether the waste is hazardous and could
facilitate enforcement because inspectors need only compare the waste
to the listing description to verify the applicability of hazardous
waste requirements.
In response, the Agency notes that it did carefully consider the
impact listing might have for solvent wastes that are already hazardous
due to the characteristics, or mixture with hazardous waste. For the
wastes under consideration in this rulemaking, EPA believes that the
characteristics provide adequate regulatory control. EPA initially
evaluated potential risks from all wastes and found risks of possible
concern due to air releases from some wastes (for acetonitrile and 2-
methoxyethanol; see proposed rule 61 FR 42327-42332). However, the
wastes with the apparent risks were already regulated as hazardous.
After considering the regulatory controls required, the residual risks
were found to be below levels of concern. Based on assessments of risks
posed by these wastes, in conjunction with the existing regulatory
controls afforded by the existing characteristics and listings, the
Agency determined that the solvent wastes as they are generated and
managed do not pose a threat to human health or the environment.
Therefore, the Agency has decided that listing is not warranted. While
listing would obviate the need for testing (for those wastes not
already listed or mixed with a listed waste), this is not a compelling
reason by itself to list. A listing may assist enforcement to some
extent; however, EPA has no indication that there is any problem in the
implementation of the characteristic regulations for these wastes. On
the contrary, the data collected indicate that generators are, in fact,
managing the wastes of concern as hazardous when they are subject to
such regulations.
The commenter states that EPA never addresses the actual or
potential reclamation of characteristic solvent sludges and byproducts
(See 40 CFR 261.2, Table 1). The commenter also argued that the
regulatory status of residuals from the recovery of spent solvent
wastes are different for listed wastes; if listed, the residuals are
hazardous, but if not listed the residuals would be unregulated, unless
they exhibit a hazardous characteristic.
The Agency disagrees with the statement that EPA did not consider
reclamation. The Agency examined all residuals generated, including
those generated from on-site recycling operations. Through the Survey,
the Agency collected data on actual or potential solvent recycling and
reclamation possibilities. Among the residuals evaluated are heavy
ends, filtrates/decantates/distillates, organic/aqueous treated
residuals, and filter related media; these were, in part, generated
from the recovery of spent solvents or the treatment on-site of spent
solvent residuals. Some facilities have the means and the financial
incentive to perform reclamation of used solvents (often in-process).
Other facilities are prevented from performing any sort of reclamation
due to process purity requirements and product quality needs (e.g.,
pharmaceutical drugs, semiconductors), which may include regulatory
requirements (e.g., purity requirements for drugs under the Food, Drug
and Cosmetic Act). Aside from value to fuel blenders and incinerators,
very little market seems to exist for many spent solvents or their
sludges. While it is true that the regulatory status of recovery
residuals is different for listed, as opposed to characteristic
hazardous waste, EPA does not believe that this would, by itself,
provide a strong reason for listing, unless risks can be demonstrated
for such wastes. EPA has no data on the characteristics of such off-
site residuals, and in fact has no indication that many of the spent
solvents at issue are sent for off-site reclamation, beyond thermal
treatment. Furthermore, in making a listing determination, EPA's
primary focus is the wastes generated on-site, and not treatment
residuals that may be generated off-site. To fully consider these
derivative wastes would expand the scope of a listing into a much
larger effort. EPA has chosen to examine wastes for which it can
reasonably expect to collect sufficient data to support a listing
evaluation.
The commenter goes on to state that in the HWIR rulemaking, EPA has
not set exit levels for most of the solvents covered by the instant
rulemaking. Therefore, wastes may meet the HWIR exit levels but still
contain substantial concentrations of non-listed solvents. The
commenter stated that by listing as hazardous the solvents in this
rulemaking, EPA would then develop exit levels for the solvents, thus
ensuring the concentrations of these solvents in waste mixtures are
reduced to protective levels prior to leaving the Subtitle C regulatory
system.
The commenter is premature in assuming the content or effect of the
HWIR rulemaking, and an assessment of the effect of that potential rule
on residuals addressed in today's final rule is speculative. The Agency
points out, however, that the concentrated waste mixtures reported for
the solvents at issue are unlikely to be realistic candidates for
exemption under HWIR. Due to the high levels of other constituents,
these wastes most certainly have to be treated, such that the wastes
that might ultimately exit the RCRA system would be treatment
residuals. Concentrated organic wastes are invariably treated through
incineration or other thermal treatment, and such treatment would
likely destroy the solvents in question, as well as the
[[Page 64393]]
other hazardous constituents. Furthermore, wastes that are
characteristic must be treated for underlying constituents under the
Land disposal restrictions (LDR) regulations. Thus, residuals that are
exempted under HWIR are not likely to have solvent levels of any
concern.
The commenter also stated that by listing the wastes as hazardous,
EPA can encourage pollution prevention activities associated with
solvent uses and waste management, including but not limited to solvent
substitution, process changes and less reliance on combustion. The
commenter noted that, through the listing process, EPA could ensure
that the wastes will always be managed as hazardous, recognizing that
attempts to identify solvent uses and users in the proposal are at
best, substantially incomplete and subject to change. The commenter
stated that it is entirely plausible that pollution prevention programs
emphasizing hazardous waste generation reductions, the increasing cost
of disposal associated with the upcoming hazardous waste combustion
rules, and other factors will encourage hazardous solvent waste
generators to reduce or eliminate the use of listed hazardous waste
solvents. Under these circumstances, current codisposal practices are
not indicative of future mismanagement scenarios.
The Agency believes that the existing regulatory requirements for
these wastes, many of which are hazardous already, provide ample
incentives for pollution prevention, both because of liability concerns
and disposal costs associated with hazardous wastes. In addition, as
noted above, under the LDR regulations, characteristically hazardous
wastes must be treated for underlying hazardous constituents. The
Agency has reason to believe that industry voluntarily assesses
opportunities for pollution prevention. As stated in the Listing
Background Document (page 17), all but four of these chemicals are
reportable in TRI Form R. Part of that reporting package includes
pollution prevention and waste minimization. As an example, use of the
three glycol ether chemicals under consideration in this rulemaking (2-
methoxyethanol, 2-methoxyethanol acetate, and 2-ethoxyethanol acetate)
has diminished significantly, and production of 2-methoxyethanol
acetate has been eliminated. Further, the cost of these chemicals is
high in comparison with other comparable chemicals. These chemicals are
used in industry only when their application is considered so suitable
as to overcome any price disadvantages. As a result, for the solvents
under consideration in this rulemaking, both regulatory requirements
(e.g., characteristics, TRI) and economic factors play a role in
encouraging companies to undertake pollution prevention assessments and
institute changes where possible. Thus, EPA finds no reasonable basis
to project changes in management practices reported in the 3007 Survey,
as suggested by the commenter.
The Agency has no reason to suspect that current management
practices would be likely to change in the future to a practice that
would pose a substantial risk to human health or the environment (e.g.,
from thermal treatment to land disposal or from a tank-based system to
a surface impoundment) due to the regulatory prohibitions, heating
value of the waste and/or requirements of the facility's wastewater
treatment systems.
The commenter also stated that EPA's assumption that analogous
waste streams generated by all industry sectors using any of the
solvents always generate an ignitable hazardous waste (based on the
fact that some of the wastes reported to the Agency in the
questionnaires are ignitable hazardous wastes), and will continue to do
so, is not sustainable given the limitations associated with the
preliminary and final questionnaires.
EPA disagrees. Nowhere does the Agency assume that analogous
wastestreams generated by all industry sectors using a particular
solvent always generate an ignitable waste. The Agency has determined,
based on reported management practices, that additional management
practices for high solvent concentration/high organic containing wastes
other than those considered in the risk assessment are not likely to
exist. While some solvents may exist in mixtures at levels that do not
exhibit the ignitability characteristic, EPA assessed risks from such
mixtures as reported in the 3007 Survey. In fact, the initial risk
analyses for all solvents did assess the risks from the wastes reported
to be hazardous. Except for the cases of acetonitrile and 2-
methoxyethanol, EPA did not pursue the impact of the hazardous waste
designations, because the risk results for the other solvents were
below levels of concern. In the next phase of risk analyses for
acetonitrile and 2-methoxyethanol, the Agency did not find significant
risks from any remaining nonhazardous wastes. (See Supplemental Risk
Assessment document for more details.)
The Agency found that process and other limitations are a technical
and regulatory bar to using the 14 chemicals alone or in combination
with non-listed solvent wastes. For example, FDA regulations preclude
solvent substitution in the pharmaceutical industry. Similarly,
chemical purity concerns and final product quality requirements often
specify the chemicals to be used.
Another commenter stated that EPA had wrongly assumed that the 10
solvent wastes are already captured as hazardous by the
characteristics. The commenter states that four of the ten solvents of
concern have flash points that do not meet the characteristic of
ignitability: phenol, isophorone, furfural and cyclohexanol. Wastes
from these four chemicals could never exhibit the characteristic of
ignitability, unless generated in mixtures with some other component
that has a low enough flash point. Two commenters provided
calculations, using Raoult's Law and the lower flammability limit, of
the potential concentration of solvents in a mixture that would result
in an ignitable waste. These commenters contend that the solvent
concentration in the mixtures must be very high to produce a mixture
that is ignitable.
As noted above, EPA did not need to rely on the fact that all waste
mixtures would be ignitable. Certainly for the four solvents mentioned
by the commenter, EPA did not rely only on the hazardous waste
designations, but rather presented risk results for all wastes
reported. In addition, the amount of solvent in nonwastewaters for two
of the chemicals cited were extremely small (cyclohexanol-16 kg;
furfural-<1 kg). Thus it is highly unlikely that these wastes could
present any significant risk, regardless of whether or not the wastes
were designated as hazardous.
Furthermore, the commenters' calculations are based on the lowest
solvent concentration waste being mixed with an organic chemical and
the highest solvent concentration waste being mixed with water.
However, most of the lower concentration solvent wastes reported are
mixed with water (at concentrations of solvent much lower than those
presented by the commenter), are managed in a tank-based wastewater
treatment system, and undergo biological treatment. Most of the higher
concentration solvent wastes reported are mixed with other organics and
are managed by some type of thermal treatment due to the heating value
of the waste.
3. Waste-Specific Rationales and Response to Specific Comments
Acetonitrile. Decision. EPA is not listing wastes from the solvent
use of acetonitrile as hazardous waste under 40 CFR 261.31. As
described in the
[[Page 64394]]
proposed rule and as modified by subsequent analysis in response to
comments, EPA finds no significant risks from treatment in aerated
tanks or combustion in a boiler. EPA concludes that potential risks
from air releases of acetonitrile stored in open accumulation tanks
(i.e., on-site storage tanks) are also not significant, because the
vast majority of the nonwastewater residuals stored are already
regulated as hazardous waste. In the latter case regulatory controls
afforded by the existing solvent listings and the characteristics
(primarily ignitability) are protective of human health and the
environment.
EPA's final determination not to list this solvent is also based on
the analysis in the proposed rule (see 61 FR 42328), as modified by
subsequent analysis in response to comment, that potential risks from
land-based management of acetonitrile wastes are not significant. All
wastewaters found in EPA's 3007 Survey were treated in tanks, except
for several wastes that were reported to enter impoundments as part of
a wastewater treatment train in volumes that would not present
significant risk. In response to comments, EPA conducted further
analysis of the potential risks that might arise from treatment of
acetonitrile wastewaters in a surface impoundment. This analysis
included consideration of any additional risk resulting from
noningestion exposure from groundwater (e.g., inhalation). As described
in section IV.C, these analyses further confirmed this management
practice presents no significant risks (see Table 3).
The proposal also found that the few wastes reported to go to
landfills typically contained negligible levels of acetonitrile
solvents, and were not of concern. In response to comments, EPA further
examined the potential for risks that might arise if more concentrated
wastes were placed in an unlined Subtitle D landfill, but continues to
believe such risks are not of concern (see specific comments below).
As described in section IV.B, EPA updated its risk analysis for
acetonitrile for some management scenarios. While the updated analyses
confirmed the evaluation in the proposed rule, the updated analysis for
aerated wastewater treatment tanks showed an HQ of two, which is
slightly above the Agency's presumptive no-list HQ level of one. EPA
does not believe this marginal risk is significant for the following
reasons. First and foremost, as noted earlier in section IV.B, the
analysis that resulted in the HQ of two is actually more conservative
than a true double-high end analysis. The dispersion modeling used in
calculating the HQ of two incorporates a high-end receptor distance, in
addition to two other high-end parameters used (solvent loading and
tank scenario). Furthermore, the solvent loading used for this analysis
was the maximum reported for acetonitrile in wastewaters, rather than
the 90th percentile value that EPA typically uses to estimate high-end
risks (see for example the risk analyses in the recent Petroleum
Listing, 63 FR at 42117). In the 3007 Survey for solvent use,
facilities reported the treatment of 26 acetonitrile wastewaters in
tanks (see the Listing Background Document, App. I), and the maximum
was above the 90th% value for the mass loadings from this distribution.
EPA used the second highest loading, which was an order of magnitude
below the maximum, to see the impact of using this value in the updated
analysis. When using the 2nd highest loading, EPA calculated an HQ of
0.02, or well below one. Thus, the HQ of two is an overestimate and
does not reflect a significant risk. As further confirmation, EPA also
estimated risks for acetonitrile wastes using the methodology from the
Air Characteristic Study. This methodology allowed receptor distance to
be varied and was thus closer to a true high-end analysis. Using either
the maximum acetonitrile loading or the second highest loading, the
estimated HQ's were below 1.0 (0.7 and 0.08 respectively). Finally, EPA
has recently promulgated regulations under the Clean Air Act (CAA) to
control air releases from the industry represented by the one facility
with the maximum loading (September 11, 1998, 63 FR 50280). These
standards control releases of hazardous air pollutants, such as
acetonitrile, from wastewater treatment systems at pharmaceutical
producers. Therefore, for these reasons the Agency does not believe
that the risks from acetonitrile in wastewater treatment tanks are
likely to be significant.
Given that nearly all of the nonwastewater acetonitrile residuals
are either already being handled as hazardous, and those that are not
handled that way contain negligible amounts of the solvent, these spent
solvent residuals are not likely to pose a significant hazard to human
health or the environment. Furthermore, treatment of wastewaters in
tanks, or in rare cases in impoundments, presents no significant risks.
Therefore, the Agency continues to believe that a no-list decision is
warranted.
Specific comments. Several commenters support EPA's no list
decision on Acetonitrile. The commenters confirmed that the management
practices and characterization of wastewater and nonwastewater
residuals from the use of acetonitrile as a solvent have been properly
identified. One commenter also noted that the risk assessment conducted
by the Agency supports the determination not to list acetonitrile spent
solvents. However, another commenter disagreed with the Agency's
findings, stating that, despite shortcomings in EPA's risk assessment,
the high-end analysis for tank storage resulted in an estimated HQ of
200, orders of magnitude higher than the HQ of 1 typically warranting a
hazardous waste listing. This commenter noted that only by performing
the Phase III assessment was the Agency able to rationalize a no-list
decision.
In response, EPA wishes to clarify the meaning of the different
phases of the risk assessment. The iterative process of risk assessment
began with bounding analyses as the first phase. This type of analysis
(by definition) involves conditions so unlikely as to be virtually
impossible. Many scenarios did not show significant risk. Those
scenarios which showed significant risk under bounding conditions were
assessed under ``high-end'' conditions in Phase II. This was a more
realistic assessment, but still reflected close to a ``worst-case'' set
of conditions.
Of all scenarios evaluated for acetonitrile, only one showed
significant risk when modeled under high-end conditions, an uncovered
storage tank (also called on-site accumulation in the proposal). The
commenter refers to the hazard quotient of 200 calculated for this
scenario. However, this result was reported as an intermediate step in
the risk assessment process. EPA had significant concerns about this
result for two basic reasons. First, this scenario involved storage of
solvent wastes pending incineration. Modeling limitations required the
Agency to estimate risks based on solvent storage in tanks without
covers of any kind. In fact, the scenario assumed that essentially all
of the stored acetonitrile would volatilize from the tanks before
incineration could take place. The Agency judged this scenario highly
unlikely because the waste is being stored for thermal treatment, and
it is irrational to assume valuable fuels would be allowed to escape in
such a manner. Further, as explained in the proposed rule, the vast
majority of the wastes are already classified as hazardous waste
because they are either characteristically hazardous, or co-managed
with listed hazardous wastes. As such, the storage units would have to
comply with RCRA regulations
[[Page 64395]]
promulgated to control such air releases (see 40 CFR part 264, subpart
CC). Thus, the HQ of 200 is clearly an overestimate, because it was
based on modeling releases for wastes that are already hazardous.
In order to assess potential risks from the nonhazardous wastes
that were not already subject to Subtitle C controls, the Agency
refocused the assessment on the nonregulated waste streams in this
scenario (acetonitrile in storage tanks). This third phase of the risk
assessment, is a normal and logical step in the iterative risk
assessment process. Phase III of the assessment showed that a bounding
analysis of these wastes resulted in an HQ below one. Therefore, EPA
concluded that the risks from the nonhazardous portion of the
acetonitrile wastes are not significant, and that listing of solvent
wastes from the use of acetonitrile is not warranted.
One commenter states that large quantities of acetonitrile wastes
are generated in concentrations well in excess of levels capable of
posing a substantial risk to human health or the environment, and are
managed in ways inconsistent with the Congressional directive to
minimize the toxicity of mobility of wastes destined for land disposal.
The commenter stated that large quantities of solids containing 10,000
ppm solvent are disposed in hazardous waste landfills, while the
Universal Treatment Standard (UTS) applicable to acetonitrile is 1.8
ppm.
EPA disagrees that large quantities are generated that present
substantial risks. The Agency evaluated risks based on potential
exposures arising from plausible management. The highest concentration
of acetonitrile going into a surface impoundment is no higher than 0.04
mg/L (see Listing Background Document, Table 3-2). In fact, it would
likely be much lower, since those wastewaters are pretreated before
entering the impoundment. As described in section IV.C.1, further
modeling done for surface impoundments confirmed that risks from such
levels were not significant.
The commenter is incorrect in stating that large quantities of
solids containing 10,000 ppm acetonitrile are disposed in hazardous
waste landfills. First, as noted previously, very few acetonitrile
wastes were sent to landfills, i.e., four out of the 254 wastes
reported in the Survey. The commenter singled out the one waste with
appreciable acetonitrile loading (454 kg/yr.). In EPA's view, this one
waste is not reflective of ``large quantities'' going to landfills.
Furthermore, as described further in the following response, the
practice is no longer occurring, and the facility in question is
currently sending this waste stream for fuel blending, in recognition
of its fuel value.
The Agency disagrees with the commenter's conclusion that current
management practices are inconsistent with the Congressional directive
to minimize the toxicity and mobility of wastes destined for land
disposal. The vast majority of the acetonitrile waste (nonwastewater),
both by volume (99%) and by acetonitrile loading (99%), is not managed
in land-based units. Furthermore, as noted above, the vast majority of
acetonitrile wastes are already hazardous, and as such, must meet the
Land Disposal Treatment standards prior to land disposal.
Finally, as described earlier in today's document, some commenters
argued that EPA should examine more land disposal scenarios, such as
landfills. In response, the Agency examined groundwater ingestion risks
from the disposal of acetonitrile solids in an unlined landfill. The
Agency still believes that landfill disposal of acetonitrile is not a
plausible management scenario, and there is no evidence that such waste
has ever been disposed in Subtitle D landfills. To the contrary, the
only facility that had been sending a significant acetonitrile loading
to a landfill (454 kg/yr) sent the waste to a Subtitle C landfill.
Furthermore the facility indicated that it had ceased this practice
during 1993 and started sending the waste for thermal treatment because
of the waste's fuel value. (EPA has received confirmation from the
generator of this waste that the material has fuel value on the order
of 14,800 BTU per pound.1) Thus, EPA believes that such
wastes will be sent for thermal treatment under the current regulatory
structure. The Agency decided, however, to examine the resulting risks
if such disposal were to occur in an unlined Subtitle D landfill. As
described in more detail in the Supplemental Risk Assessment, the
resulting analysis suggested hazard quotients in the range of 11-22 for
a high-end scenario.
---------------------------------------------------------------------------
\1\ See contact report dated June 10, 1998 documenting a
telephone conversation with Dave Giffen, B.F. Goodrich, which is
located in the docket accompanying today's rule.
---------------------------------------------------------------------------
EPA does not view these risks as significant, however, for several
reasons. First, as noted above, landfill disposal is unlikely given the
fuel value of the material, thus EPA does not view disposal in a D
landfill plausible. In any event, the elevated HQs were projected for
only one waste out of the 254 acetonitrile wastes identified in the
3007 Survey. Even if EPA found that the elevated HQs reflected a
plausible management scenario, the Agency might well decide that the
potential risk posed by this one waste does not merit listing of all
acetonitrile residuals generated. Given the widely varying nature of
the industries and wastes involved, and the very small percentage of
management activities that even arguably could present a risk of
concern, the Agency believes that a broad listing for solvent use would
result in over regulation. In any case, EPA concludes that wastes such
as these are not likely to be disposed in landfills, and are therefore
unlikely to pose significant risks.
Phenol. Decision. EPA is not listing wastes from the solvent use of
phenol as hazardous waste under 40 CFR 261.31. As described in the
proposed rule and as modified by subsequent analysis in response to
comments, EPA finds no significant risks from treatment in aerated
tanks, storage in tanks, or combustion in a boiler. Furthermore, EPA
does not believe that potential risks from land-based management of
phenol wastes are significant. None of the wastes containing phenol
were reported to go to landfills. Wastes with high organic content that
contain any appreciable levels of phenol were classified as hazardous
waste, and were sent for fuel blending or incineration as hazardous.
Wastewaters were generated from the specialized use of phenol as a
solvent in the extraction of materials from crude oil, and the
resulting spent phenol wastes were sent to wastewater treatment systems
for treatment in tanks or surface impoundments. EPA found risks from
impoundments would be low given the dilution and treatment that occurs
in these wastewater treatment systems, and the specific facts
associated with the impoundment of potential concern (see 61 FR 42337).
In response to comments, EPA conducted further analyses of the
potential risks that might arise from treatment of phenol wastewaters
in a surface impoundment. In these analyses EPA also included
consideration of any additional risk resulting from noningestion
exposure from groundwater (e.g., inhalation), as well as codisposal
with other solvent wastes under evaluation. As described in section
IV.C, these analyses further confirmed this management practice
presents no significant risks. EPA used the updated toxicological
benchmark discussed in section III of today's rule for all additional
analyses. The Agency also used the updated toxicological benchmark to
revise the risk assessment results for other practices, i.e., storage
and treatment in tanks, and found this
[[Page 64396]]
had no significant impact on the risks (see Table 3).
Based the results of the risk analyses in the proposal, as well as
the updated evaluations, these spent solvent residuals are not likely
to pose a significant hazard to human health or the environment.
Therefore, the Agency continues to believe that a no-list decision is
warranted.
Specific comments. One commenter supported EPA's decision not to
list wastes from solvent uses of phenol as hazardous wastes. The
commenter agrees with EPA that phenol does not satisfy the criteria for
listing in 40 CFR 261.11(a)(3). However, another commenter stated that
there are cases where phenol is currently used by itself (without being
mixed with other F-listed wastes) as an industrial solvent and with
this decision ``not to list'' phenol as a hazardous waste, EPA would
seem to provide disposal option ``carte blanche'' for current users.
Manufacturers can modify their processes to use these solvents, which
would no longer be considered hazardous wastes, according to this
commenter.
In response, the Agency believes it unlikely that facilities would
change their management practices based on the information collected in
the Survey. The Survey indicated that all nonwastewater residuals
containing phenol were managed as hazardous except one, which is
managed by incineration. Thus, the solvent users managed their wastes
as hazardous under the existing regulatory framework. There is no
evidence that any facility that has not modified their process to use
these solvents to date will do so after a no-list decision. Except for
the facilities that use phenol for extracting lube oil, most facilities
that use phenol as a solvent use it in laboratories or other specialty
uses, and the waste solvents are sent for offsite treatment via
incineration as hazardous waste. EPA has no indication that such
generators could easily modify their use and accumulation practices in
an attempt to generate nonhazardous material, nor is there any
indication that facilities would do so.
A third commenter stated that EPA's decisions regarding plausible
mismanagement scenarios are especially suspect in the case of phenol,
because phenol is the 33rd highest volume chemical produced in the
United States, is already widely used, and its use is projected to
increase. The commenter stated that EPA did not adequately evaluate
groundwater risks posed by phenol.
EPA disagrees with the commenter's inference that projected
production increases in phenol are destined for solvent use. In fact,
more than 96% of the phenol consumed in the U.S. is for nonsolvent uses
(see SRI Chemical Economics Handbook, 1996). Increasing demand for
products produced from phenol is due to increases for production of
caprolactam, aniline, and bisphenol-A, (e.g., see http://
www.chemicalweek.com/marketplace/prod__focus.html). Nearly all of the
solvent use of this chemical (>99.9%) was attributed to the petroleum
industry, of which the Agency conducted a complete survey. Given that
the major uses of this solvent were very specialized (i.e., extraction
of lube oil), the Agency is confident that no other significant uses
are likely to exist. Contrary to the comment, damage from groundwater
contamination was evaluated for the proposed rule, and a refined
assessment was conducted for the final rule, and noted in section IV.B.
These analyses did not find significant groundwater risks (see Table
2), and details are given in the Supplemental Risk Assessment document
in the docket.
The commenter also noted that EPA's Hazardous Waste Characteristic
Scoping Study (November 1996) showed that phenol releases originated
from nonhazardous waste management units, principally landfills and
surface impoundments. The Scoping Study, which expressly excluded
product spills and accident releases, presents clear evidence of the
potential risks posed by the improper management of phenol wastes, and
the use of nonhazardous surface impoundments and landfills as plausible
mismanagement scenarios for phenol and other solvent wastes. The
commenter went on to state that EPA assumed tanks never leak, and
landfills would never be used, because none were reported by the 31
facilities receiving the final questionnaire.
The Agency disagrees that this aspect of the Characteristic Scoping
Study is relevant to the Solvents Listing Determination. As EPA noted
in the proposed rule, damage cases reviewed did not show evidence
linking the phenol contamination at damage sites, including
nonhazardous landfills and surface impoundments, to phenol use as a
solvent. Without evidence that the mismanagement of phenol wastes
resulting in contamination is linked to solvent use, the damage
incidents are not an adequate basis for listing phenol as a spent
solvent. As noted above, the vast majority of phenol is used for
nonsolvent uses. Therefore simply pointing to damage case analyses is
not compelling evidence for listing phenol wastes that result only from
its use as a solvent. If EPA were to determine that certain industries
that use phenol for nonsolvent uses are mismanaging wastes and causing
significant environmental problems, then the Agency would consider
other regulatory approaches. However, EPA's examination of the limited
solvent use of this chemical indicates that such uses are not likely to
generate wastes of concern. Thus, a listing of spent solvent wastes for
this chemical would not be a practical way to address the types of
environmental concerns raised by the commenter.
EPA responded to the general issues of tanks and landfill disposal
elsewhere in today's document. In the case of phenol, the Agency did
not consider the disposal of phenol-containing wastestreams in a
landfill to be a plausible management scenario for several reasons.
None of the 38 wastestreams containing spent phenol reported in the
3007 Survey are managed in a landfill. One reason for this is that very
few phenol wastes are solids (most are organic or aqueous liquids).
Only one solid wastestream, spent carbon, contained significant levels
of phenol. This was sent offsite for regeneration or incineration. EPA
has no reason to conclude that the practice of landfilling will
increase. Wastes with higher organic content are thermally treated, and
92% of the thermal treatment was conducted in hazardous waste units or
through fuel blending for future burning. Therefore, EPA has no basis
to project that wastes with significant phenol concentration are likely
to be placed in a landfill.
Methyl Chloride. Decision. EPA is not listing wastes from the
solvent use of methyl chloride as hazardous waste under 40 CFR 261.31.
As described in the proposed rule and as modified by subsequent
analysis in response to comments, EPA finds treatment in aerated tanks
and surface impoundments, storage in tanks, or combustion in a boiler
do not present significant risk. The vast majority of methyl chloride
produced is used as an intermediate in chemical manufacturing, and very
few uses as a solvent were identified. Essentially all of the wastes
reported from the solvent uses of methyl chloride were limited to two
facilities that produce butyl rubber. While some of the updated
lifetime individual excess cancer risks in Table 3 for storage in tanks
and wastewater treatment in tanks/surface impoundments were above 1E-
06, the risks are below the 1E-05 level typically used by the Agency
for identifying
[[Page 64397]]
candidate wastes for listing. Furthermore, as described below, the
consideration of other factors indicate these risks are not
significant.
The high-end risks for storage tanks (4E-06 from the updated
analysis and 2E-06 from the Air Characteristic approach) are highly
likely to be overestimates, because the analyses assumed that all of
the methyl chloride in the stored solvent waste would be released. This
assumption is unlikely for materials being stored expressly to send for
thermal treatment. Furthermore, these wastes were reported to be
already regulated as hazardous, and would be subject to RCRA
regulations limiting air releases under 40 CFR part 264, subpart CC.
The risks found for wastewater treatment tanks (1E-06 from the
updated analysis, and 1E-07 from the Air Characteristic approach) are
at or below EPA's presumptive no-list level of 1E-06, and do not appear
of concern. In addition, these are likely to be overestimates, because
the concentration modeled for this scenario was 10 ppm, even though the
value was actually reported as less than 10 ppm. EPA's updated
assessment of the one wastewater reported to be treated in a surface
impoundment showed a high-end risk of 4E-06. However the one
impoundment that managed this waste is already a permitted Subtitle C
hazardous waste unit, and is therefore subject to regulations limiting
air releases (see 40 CFR part 264, subpart CC) and groundwater release
( 40 CFR part 264, subparts F and K,).
In addition, potential air releases from this industry are being
addressed by other regulations promulgated under the Clean Air Act (see
61 FR 46906, September 5, 1996). These regulations control releases of
hazardous air pollutants from process units, storage tanks and
wastewater treatment systems. EPA believes that these air regulations
provide a more integrated approach to controlling air risks than would
be possible under the limited controls available for air releases under
the RCRA listing program.
Based on the analysis in the proposal, the updated evaluations, and
the other factors discussed in this document and the proposal, the
methyl chloride solvent wastes are not likely to pose a significant
hazard to human health or the environment. Therefore, the Agency
continues to believe that a no-list decision is warranted.
Specific Comments. One commenter supported the Agency's decision
not to list methyl chloride. However, another commenter stated that the
Agency left potential risks posed by the groundwater exposure pathway
unevaluated by assuming methyl chloride was managed only in a permitted
surface impoundment, that tanks never leak, and that landfills would
never be used.
As discussed more detail in the proposed rule (see 61 FR at 42334-
42335), the Agency did evaluate the groundwater exposure pathway
through management scenarios where groundwater exposure was plausible.
Wastes with high organic content were regulated as hazardous and
incinerated. Waste solids were rarely sent to landfills, and in these
cases the concentrations of methyl chloride were negligible. The only
wastes sent to landfills were a small volume of spent desiccant that
contained <5 kg of methyl chloride, and a larger volume sludge/ash from
a sludge treatment unit which was reported to have a ``trace'' amount
of methyl chloride. Given that this chemical is readily treated by
biodegradation and volatilization in an aerated biological treatment
system, it is unlikely that any significant levels of methyl chloride
remain in this residual. EPA believes that these very low concentration
wastes reflect the types of waste solids that are likely to be sent to
landfills. EPA also notes that other nonwastewaters containing any
reported levels of methyl chloride (a total loading of 1.6 kg) were
regulated as hazardous waste, making disposal in an unlined Subtitle D
landfill illegal. Thus, significant groundwater risks from landfills
are unlikely to occur.
The very limited solvent use of this chemical, and its unique
characteristics (a gas at room temperature) lead EPA to conclude that
it is unlikely that other solvent wastes would be generated that are
managed in other surface impoundments beyond the example documented in
the 3007 survey. As noted above, this impoundment is a hazardous waste
unit, and is therefore subject to RCRA regulations limiting groundwater
releases. Furthermore, as noted in the proposed rule, methyl chloride
is readily treated by biodegradation and volatilization in waste water
treatment systems, and thus is unlikely to migrate to the groundwater.
Also, the tendency of methyl chloride to hydrolyze in water to methanol
suggests that transport to receptors by groundwater is not likely to be
significant.
One commenter argued that EPA failed to adequately consider the
formation of products of incomplete combustion (PICs) for methyl
chloride. The commenter stated that EPA claimed PIC emissions were not
cause for concern because the reported waste in question happened to be
managed in a hazardous waste combustor, and disagreed with EPA's
presumption that this one waste management practice reported represents
current and future combustion activities.
As noted above, the solvent uses of methyl chloride are very
specialized, and the number of wastes sent for incineration are
limited. The three wastes with reported concentrations that went to
thermal treatment were all classified as hazardous waste and were
treated as such under RCRA regulations. (Two wastes incinerated were
treatment sludges that were reported to contain no significant levels
of methyl chloride). Given these reported practices, and the very
limited solvent uses for this chemical, EPA believes that combustion of
solvent wastes with appreciable methyl chloride is likely to occur in
RCRA regulated units. Therefore, the Agency believes its presumption
for management is valid in this case. In addition, EPA is not aware of
any precise way of predicting the kinds or levels of PICs that might be
generated in a nonhazardous boiler, especially because the wastes in
question would make up only a very small fraction of the wastes being
treated.
Nevertheless, EPA did consider the possibility of PIC formation for
incineration of methyl chloride wastes. As discussed in the preamble to
the proposed rule (61 FR 42334), the amount of methyl chloride in the
wastes that are incinerated is extremely small (i.e., 2 kg). The
loading of methyl chloride sent to a boiler or industrial furnace
(BIF), although larger (i.e., at 2,250 kg) than the amount sent to an
incinerator, is in a waste that is hazardous due to ignitability and
toxicity characteristics, and therefore must be treated as hazardous
wastes. This latter waste is generated from the use of methyl chloride
in butyl rubber manufacturing, and it is unlikely that such a complex
process could (or would) be modified to avoid generating waste methyl
chloride in association with high levels of ignitable hydrocarbons.
Thus, combustion in a RCRA-regulated unit seems likely to occur for
this waste due to the specialized nature of this solvent use. These
combustion units are operated according to stringent air emission
standards that limit PIC formation (e.g., see 40 CFR part 264, subpart
O, for incinerators and part 266, subpart H, for Boilers and Industrial
Furnaces). EPA has also proposed revisions to these standards (see
61FR1538, April 19, 1996 and 62FR24212, May 2, 1997). Given these
facts, as well as the results of the risk assessment for these wastes,
EPA
[[Page 64398]]
does not believe that combustion of these wastes poses a significant
risk.
2-Methoxyethanol (2-ME). Decision EPA is not listing wastes from
the solvent use of 2-methoxyethanol (2-ME) as hazardous waste under 40
CFR 261.31. As described in the proposed rule and as modified by
subsequent analysis in response to comments, EPA found no significant
risks from treatment in aerated tanks or combustion in a boiler. EPA
also concluded that potential risks from air releases of 2-ME stored in
open accumulation tanks are also not significant, because all of the
nonwastewater residuals stored under this scenario are already
regulated as hazardous waste, either because the wastes exhibit a
characteristic, or because the 2-ME waste is commingled with listed
wastes. EPA believes that regulatory controls afforded by the existing
solvent listings and the characteristics (primarily ignitability) are
sufficiently protective of human health and the environment.
None of the wastes examined were sent to land disposal in a
landfill or impoundment. Spent solvent solids are thermally treated,
and wastewaters are all treated in tanks. In the face of the existing
practices, EPA finds it implausible that high organic wastes currently
sent to thermal treatment would be sent to landfills. Essentially all
of the nonwastewater residuals that contain spent 2-ME are thermally
treated or recovered, and nearly all (96%) are treated as hazardous
waste. Because all wastewaters are treated in tanks, EPA also does not
expect risks from surface impoundment management for these wastes.
Given that nearly all of the nonwastewater 2-ME residuals are
already being handled as hazardous, or contain negligible amounts of
the solvent, these spent solvent residuals are not likely to pose a
significant hazard to human health or the environment. Furthermore,
treatment of wastewaters in tanks presents no significant risks.
Therefore, the Agency continues to believe that a no-list decision is
warranted.
More general comments on EPA's methodology and approach that relate
to 2-ME are discussed elsewhere in today's document. The few comments
specific to 2-ME are discussed below.
Specific comments. One commenter stated that EPA completely failed
to evaluate potential risks from groundwater contamination,
notwithstanding three groundwater contamination incidents involving
this solvent identified by EPA from damage incidents.
EPA described in the proposed rule why the damage cases cited by
the commenter were not useful (see 61 FR at 42332). Of the three
problem site identified, two were old landfills that received a wide
variety of industrial and municipal wastes, and the use of 2-ME prior
to disposal was impossible to ascertain. The chemical is widely used as
a fuel additive and as a chemical intermediate. Thus, the damage could
not be tied to wastes generated from the use of this chemical as a
solvent. Damage at the third site also could not be linked to a
specific use of 2-ME. However, this site was a used oil recycling site,
and the contamination found may be related to the use of 2-ME as a fuel
additive. Furthermore, none of the reports examined by the Agency
provided any concentration of 2-ME in the groundwater. Thus, the
limited data from the damage incidents provide no reliable support for
listing wastes from the use of 2-ME as a solvent. In addition, the
industries EPA identified as solvent users of 2-ME are not represented
in the damage incidents. Finally, the vast majority of nonwastewater
solvent wastes identified in the Survey were reported to be hazardous
waste, and could not be placed in nonhazardous landfills. Thus, the
damage incidents did not provide useful information on current or
likely future waste management practices.
One commenter argued that EPA's high-end risk analysis of onsite
accumulation tank storage resulted in a HQ of 16, well above the HQ of
1 that typically warrants a hazardous waste listing. Only by performing
the completely misguided Phase III assessment was EPA able to arguably
rationalize a no-list decision.
EPA's response to this comment is similar to the response above to
essentially the same comment raised for acetonitrile. The apparent
risks cited by the commenter were from an intermediate stage of the
risk assessment, and did not reflect the fact that all nonwastewaters
were managed as hazardous waste. EPA concluded that the management
scenario referred to in the comment (on-site accumulation of
nonwastewaters in unregulated tanks) does not apply to any 2-
methoxyethanol waste streams.
2-Ethoxyethanol Acetate (2-EEA). Decision. EPA is not listing
wastes from the solvent use of 2-ethoxyethanol acetate (2-EEA) as
hazardous waste under 40 CFR 261.31. As described in the proposed rule
and as modified by subsequent analysis in response to comments, EPA
found no significant risks from treatment in aerated tanks, storage in
tanks, or combustion in a boiler. Furthermore, essentially all (99.8%)
of the nonwastewaters were reported to be hazardous and were managed as
hazardous waste through some form of thermal treatment.
None of the wastes were reported to go to land disposal in
landfills or impoundments, and these scenarios were not modeled. Given
the existing waste management practices, EPA finds it implausible that
high organic waste solids currently sent to thermal treatment would be
sent to a landfill. The high percentage of wastes that are hazardous
are precluded from disposal in an unlined Subtitle D landfill, and EPA
has no evidence to indicate that spent 2-EEA wastes would be placed in
a landfill. Due to the nature of the primary industries using 2-EEA as
a solvent (e.g., the semiconductor and electronics industries), very
few wastewaters are generated. Nearly all of the wastestreams generated
are spent solvent wastes that undergo some type of thermal treatment.
None of the wastestreams that were reported in the 3007 Survey go to a
surface impoundment. Any change from the current treatment in tanks to
treatment in impoundments seems unlikely given the capital investment
associated with tanks and the liability issues associated with
treatment in a surface impoundment. These facilities made an investment
in tank-based systems in the absence of any listing, and EPA sees no
reason why this would change if the status quo is not changed, i.e., if
the wastes are not listed. In addition to cost considerations, some
facilities may perceive other benefits from managing the waters in
tanks, such as the current exemption from RCRA permitting requirement
for such units (see 40 CFR 264.1(g)(6)). If hazardous waste were to be
treated in a wastewater treatment system, impoundments in the system
would require permitting as a Subtitle C unit. In addition, the use of
2-EEA has been decreasing in recent years, thus other new generators of
this spent solvent are unlikely.
Given that nearly all of the nonwastewater 2-EEA residuals are
already being handled as hazardous, or contain negligible amounts of
the solvent, these spent solvent residuals are not likely to pose a
significant hazard to human health or the environment. Furthermore,
treatment of wastewaters in tanks presents no significant risks.
Therefore, the Agency continues to believe that a no-list decision is
warranted.
More general comments on EPA's methodology and approach that relate
to 2-EEA are discussed elsewhere in today's document. The few comments
[[Page 64399]]
related specifically to 2-EEA are discussed below.
Specific comments. Two commenters stated that EPA failed to
consider in its risk assessment, that many of the generators manage 2-
EEA with other solvents associated with this proposed rule. EPA
calculated an HQ for 2-EEA for on-site accumulation of 0.7. Thus,
additional risk from other solvents would cause the HQ level to exceed
the threshold of one. One of the commenters went on to cite examples of
facilities in several industries (e.g., printed circuit board
manufacturers) at which multiple solvents were reported.
EPA disagrees with the commenters' concerns about multiple solvent
risks. First, the comment cited examples where the hazard quotient
would exceed one at facilities that use more than one solvent in
combination. However, the use of the chemicals at the facilities cited
by the commenter are not solvent use, within the Agency's definition.
These facilities used 2-EEA and other chemicals as components in
formulations. Thus, no spent solvent is generated and was not included
in the risk assessment.
Furthermore, the HQ value of 0.7 cited by the commenter for on-site
accumulation is likely to be unrealistically high for the reasons cited
for the Phase II results for acetonitrile. The key reason is that
essentially all residuals stored prior to thermal treatment were, in
fact, already hazardous waste. Thus, air emissions from these wastes
are already regulated under RCRA subpart CC to 40 CFR part 264, making
the scenario of storage in an open tank unrealistic. EPA did not pursue
a third phase of analysis for 2-EEA because the HQ was below one in the
Phase II evaluation. Furthermore, the only wastes reported that were
not hazardous consisted of one insignificant loading (<1 kg), and one
waste characterized as ``containers/rags'' which contained very low
levels of the solvent (<6 kg). Thus, EPA decided further analysis was
not needed. As described in the Risk Assessment section, EPA addressed
the general comment of the impact of multiple solvents in some wastes
by conducting an assessment of the potential for cumulative risks.
One commenter stated that the concentrations of 2-EEA in solvent
nonwastewaters range from 0.1% to 100%. These ranges are not consistent
with the Agency's position that nonwastewaters would always be managed
as a hazardous waste due to ignitability, particularly where the
solvent is not co-managed with listed solvent wastes. The commenter was
also concerned because the concentration of 2-EEA in wastewaters ranges
from 200-20,000 ppm.
While the levels of 2-EEA in solvent nonwastewaters are variable,
the reported data clearly indicate that essentially all 2-EEA solvent
wastes generated were hazardous, and that these were all incinerated.
Concerning the wastewaters, EPA believes the commenter's concern is
unfounded. EPA's risk assessment included an analysis of potential
risks from air releases from an aerated wastewater treatment tank, and
found risks to be well below levels of concern.
Furfural. Decision. EPA is not listing wastes from the solvent use
of furfural as hazardous waste under 40 CFR 261.31. As described in the
proposed rule and as modified by subsequent analysis in response to
comments, EPA found no significant risks from treatment in aerated
tanks or surface impoundments, storage in tanks, or combustion in
boilers. Essentially all of the solvent use of this chemical (greater
than 99.99%) is in the petroleum industry as an extractant for lube
oil. Thus, solvent use of furfural is limited, and the Agency
identified only a handful of wastes derived from this use.
The furfural solvent wastes are virtually all wastewaters (greater
than 99.99%), which were managed in wastewater treatment systems. One
of the three facility's wastewater treatment systems uses a surface
impoundment, and EPA's bounding analysis for the proposed rule showed
no risks of concern from ingestion of groundwater, or inhalation of
possible air releases (HQ <1; see 61 FR at 42341).
In response to comments, EPA conducted further analyses of the
potential risks that might arise from treatment of furfural wastewaters
in a surface impoundment. In these analyses EPA also included
consideration of any additional risk resulting from non-ingestion
exposure from groundwater (e.g., inhalation). As shown in Table 3, the
high-end risk analyses showed that these wastewaters do not present
significant risks via either groundwater releases (HQ = 0.46), or air
releases (HQ = 0.11).
Based the results of the risk analyses in the proposal, the updated
evaluations, and the other factors discussed in this document and the
proposal, the furfural solvent wastes are not likely to pose a
significant hazard to human health or the environment. Therefore, the
Agency continues to believe that a no-list decision is warranted.
General comments on EPA's methodology and approach that relate to
furfural are discussed elsewhere in today's document. EPA did not
receive any other specific comments on EPA's decision not to list
furfural solvent wastes.
Cumene. Decision. EPA is not listing wastes from the solvent use of
cumene as hazardous waste under 40 CFR 261.31. As described in the
proposed rule and as modified by subsequent analysis in response to
comments, EPA found no significant risks from treatment in aerated
tanks, storage in tanks, or combustion in boilers. While cumene is used
in large volumes in the production of other chemicals, such as phenol,
its use as a solvent is limited. Essentially all of the wastes
containing cumene are thermally treated as hazardous or recovered.
Small amounts of wastewaters are sent to treatment systems, and one
resulting sludge was reported to be landfilled. However, the amount of
cumene in this sludge would be well below the maximum of 28 kg that was
used in the original solvent mixture (which contained only 1.7 % of
cumene to start with). Thus, after treatment, any risks from cumene
would be negligible. Similarly, one wastewater was reported to undergo
treatment in a surface impoundment, however, as EPA noted in the
proposal, the amount of cumene in the wastewater was small (<47 kg),
and would be further reduced by treatment.
In response to comments, EPA conducted further analyses of the
potential risks that might arise from treatment of cumene wastewaters
in a surface impoundment. In these analyses EPA also included
consideration of any additional risk resulting from non-ingestion
exposure from groundwater (e.g., inhalation during showering). As shown
in Table 2, the revised bounding analyses showed that these wastewaters
in impoundments do not present significant risks via either groundwater
releases (HQ = 0.0001), or air releases (HQ = 0.003). As noted earlier
in today's document, the toxicological values for cumene were updated
during the comment period. The new benchmarks were used in the revised
analyses, and were also used to recalculate risks derived in the
proposed rule (see Table 1). The changes reflect greater tolerance for
cumene than the previous benchmarks, and thus have no impact on EPA's
decision not to list cumene solvent wastes.
EPA also considered the potential for cumene to form NAPLs, which
might present special problems in assessing potential risks. EPA noted
in the proposed rule that cumene's water solubility is relatively low,
such that NAPLs are theoretically possible.
[[Page 64400]]
However, EPA considered the potential risks from NAPLs to be very low,
because cumene loading in wastes sent to land-based disposal was
minimal. In response to comments, EPA provided further analysis showing
that NAPL formation for these wastes is unlikely (see section IV.B).
Based the results of the risk analyses in the proposal, the updated
evaluations, and the other factors discussed in this document and the
proposal, the cumene solvent wastes are not likely to pose a
significant hazard to human health or the environment. Therefore, the
Agency continues to believe that a no-list decision is warranted.
General comments on EPA's methodology and approach that relate to
cumene are discussed elsewhere in today's document.
Cyclohexanol. Decision. EPA is not listing wastes from the solvent
use of cyclohexanol as hazardous waste under 40 CFR 261.31. As
described in the proposed rule and as modified by subsequent analysis
in response to comments, EPA found no significant risks from
accumulation in storage in tanks or combustion in boilers. The solvent
uses of cyclohexanol are limited, and few wastes containing
cyclohexanol were reported. All wastes but one are hazardous waste due
to other waste constituents or properties of the waste material. The
incinerated material contains low levels of cyclohexanol (16 kg total
loading per year). The one other waste generated was reported to go to
a nonhazardous landfill, however, this waste is a small volume (750 kg)
of filter material that contains negligible level of cyclohexanol.
Given the limited solvent uses of this chemical, and the management
practices reported, EPA believes other wastes or management practices
are not likely to be significant.
As noted earlier in today's document, the toxicological inhalation
benchmark (``provisional RfC'') for cyclohexanol was adjusted somewhat
based on peer review comments. Thus, EPA used the new benchmark to
recalculate risks derived in the proposed rule (see Table 3). The
revised HQs remain below one, and thus the updated health-based number
has no material effect on EPA's decision not to list cyclohexanol
solvent wastes.
Based the results of the risk analyses in the proposal, the updated
evaluations, and the other factors discussed in this document and the
proposal, the cyclohexanol solvent wastes are not likely to pose a
significant hazard to human health or the environment. Therefore, the
Agency continues to believe that a no-list decision is warranted.
More general comments on EPA's methodology and approach that relate
to cyclohexanol are discussed elsewhere in today's document.
Isophorone. Decision. EPA is not listing wastes from the solvent
use of isophorone as hazardous waste under 40 CFR 261.31. As described
in the proposed rule and as modified by subsequent analysis in response
to comments, EPA found no significant risks from accumulation in
storage in tanks or combustion in boilers. The solvent uses of
isophorone are limited, and few wastes containing isophorone were
reported. All wastes but one were hazardous waste due to mixture with
other listed wastes or the ignitability characteristic of the waste
material. All wastes were reported to undergo some form of thermal
treatment as a hazardous waste. Given the limited solvent uses of this
chemical, and the management practices reported, EPA believes other
wastes or management practices are likely to be significant.
As noted earlier in today's document, the toxicological value
(``provisional RfC'') for isophorone was adjusted somewhat based on
peer review comments. Thus, EPA used the new benchmark to recalculate
risks derived in the proposed rule (see Table 1). The revised HQs
remain below one, and thus the updated health-based number has no
material effect on EPA's decision not to list isophorone solvent
wastes.
Based on the results of the risk analyses in the proposal, the
updated evaluations, and the other factors discussed in this document
and the proposal, the isophorone solvent wastes are not likely to pose
a significant hazard to human health or the environment. Therefore, the
Agency continues to believe that a no-list decision is warranted.
More general comments on EPA's methodology and approach that relate
to isophorone are discussed elsewhere in today's document.
2-Methoxyethanol Acetate (2-MEA). Decision. EPA is not listing
wastes from the solvent use of 2-methoxyethanol acetate (2-MEA) as
hazardous waste under 40 CFR 261.31. As described in the proposed rule
and as modified by subsequent analysis in response to comments, EPA
found no significant risks from storage in tanks or combustion in a
boiler. 2-MEA is reportedly no longer produced domestically, and
solvent use of this chemical is limited. The few wastes generated were
classified as hazardous and were all thermally treated as hazardous
waste. Given the limited and decreasing use as a solvent, and the waste
information reported, EPA believes that other wastes and management
practices are unlikely. None of the wastes were reported to be disposed
of in landfills or impoundments, and these scenarios were not modeled.
Given the existing practice, EPA finds it implausible that high
organic waste solids currently sent to thermal treatment would be sent
to a landfill. The wastes are hazardous and thus precluded from
disposal in an unlined Subtitle D landfill. EPA has no evidence to
indicate that spent 2-MEA wastes would be placed in a landfill. Due to
the nature of the solvent uses reported for 2-MEA (diluent in coating
and reaction media), no wastewaters are generated, nor were they
expected.
Based on the results of the risk analyses in the proposal, the
updated risk analysis, and other factors noted above and in the
proposed rule, these spent solvent residuals are not likely to pose a
significant hazard to human health or the environment. Therefore, the
Agency continues to believe that a no-list decision is warranted.
More general comments on EPA's methodology and approach that relate
to isophorone are discussed elsewhere in today's document. EPA did not
receive any specific comments on EPA's decision not to list 2-MEA
solvent wastes.
Chemicals with no significant solvent use. As described in the
proposed rule and reaffirmed in this final decision, EPA did not find
any significant solvent use for four chemicals: p-dichlorobenzene,
benzyl chloride, epichlorohydrin, and ethylene dibromide. All but one
are relatively reactive chemicals, which makes them unsuitable for most
solvent applications. The other substance, p-dichlorobenzene, is a
solid at room temperature, limiting its utility as a solvent. In all
cases, the data collected by the Agency showed that any solvent use of
these chemicals is extremely limited. Some may perhaps have specialty
applications in laboratories, but no significant solvent uses were
identified. Any residuals reported from the 3007 Survey were primarily
from possible solvent use by laboratories and contain low levels of the
chemicals under study. All were coded as hazardous, except one dilute
wastewater, and were thermally treated as hazardous waste.
The Agency received no new information during the comment period
indicating that these four chemicals, (benzyl chloride,
epichlorohydrin, ethylene dibromide, and p-
[[Page 64401]]
dichlorobenzene) were used as solvents. Comments received by EPA on
this issue concurred with the Agency's decision that these four
chemicals are not used as solvents, and that they would not fit the
description for such a listing. Based on the analyses and factors noted
above and in the proposed rule, these spent solvent residuals do not
pose a significant hazard to human health or the environment.
Therefore, the Agency continues to believe that no-list decisions for
these four chemicals are warranted.
V. Regulatory Requirements
A. Regulatory Impact Analysis Pursuant to Executive Order 12866
Executive Order No. 12866 requires agencies to determine whether a
regulatory action is ``significant.'' The Order defines a
``significant'' regulatory action as one that ``is likely to result in
a rule that may: (1) have an annual effect on the economy of $100
million or more or adversely affect, in a material way, the economy, a
sector of the economy, productivity, competition, jobs, the
environment, public health or safety, or State, local, or tribal
governments or communities; (2) create serious inconsistency or
otherwise interfere with an action taken or planned by another agency;
(3) materially alter the budgetary impact of entitlements, grants, user
fees, or loan programs or the rights and obligations of recipients; or
(4) raise novel legal or policy issues arising out of legal mandates,
the President's priorities, or the principles set forth in the
Executive Order.''
The Agency estimated the costs of today's final rule to determine
if it is a significant regulation as defined by the Executive Order.
Because the Agency has decided not to list as hazardous the wastes
generated from the use of the solvents evaluated in this rulemaking, no
specific action is required under this action. As a result, there are
no costs associated with this final rule. This rule was deemed
significant for novel policy reasons by the Office of Management and
Budget (OMB) and was submitted to OMB for review.
B. Regulatory Flexibility Act
Pursuant to the Regulatory Flexibility Act (5 U.S.C. 601 et seq.,
as amended by the Small Business Regulatory Enforcement Fairness Act
(SBREFA) of 1996) whenever an agency is required to publish a document
of rulemaking for any proposed or final rule, it must prepare and make
available for public comment a regulatory flexibility analysis that
describes the effect of the rule on small entities (i.e., small
businesses, small organizations, and small governmental jurisdictions).
However, no regulatory flexibility analysis is required if the head of
an agency certifies the rule will not have a significant economic
impact on a substantial number of small entities.
SBREFA amended the Regulatory Flexibility Act to require Federal
agencies to provide a statement of the factual basis for certifying
that a rule will not have a significant economic impact on a
substantial number of small entities. The following discussion explains
EPA's determination. This rule has no effect as the Agency is issuing
this final decision not to list wastes generated from the use of 14
chemicals as solvents as hazardous under the Resource Conservation and
Recovery Act (RCRA). The determinations in this rule are limited to
specific solvent wastes. The rule does not impose new burdens on small
entities. Therefore, I hereby certify that this rule will not have a
significant economic impact on a substantial number of small entities.
This rule, therefore, does not require a regulatory flexibility
analysis.
C. Unfunded Mandates Reform Act
Title II of the Unfunded Mandates Reform Act of 1995 (UMRA), Public
Law No. 104-4, establishes requirements for Federal agencies to assess
the effects of their regulatory actions on State, local, and tribal
governments and the private sector. Under section 202 of the UMRA, EPA
generally must prepare a written statement, including a cost-benefit
analysis, for proposed and final rules with Federal mandates that may
result in expenditures to State, local, and tribal governments, in the
aggregate, or to the private sector, of $100 million or more in any one
year. Before promulgating an EPA rule for which a written statement is
needed, section 205 of the UMRA generally requires EPA to identify and
consider a reasonable number of regulatory alternatives and adopt the
least costly, most cost-effective, or least burdensome alternative that
achieves the objectives of the rule. The provisions of section 205 do
not apply when they are inconsistent with applicable law. Moreover,
section 205 allows EPA to adopt an alternative other than the least
costly, most cost-effective, or least burdensome alternative if the
Administrator publishes with the final rule an explanation why that
alternative was not adopted. Before EPA establishes any regulatory
requirements that may significantly or uniquely affect small
governments, including tribal governments, it must have developed under
section 203 of the UMRA a small government agency plan. The plan must
provide for notifying potentially affected small governments, enabling
officials of affected small governments to have meaningful and timely
input in the development of EPA regulatory proposals with significant
Federal intergovernmental mandates, and informing, educating, and
advising small governments on compliance with the regulatory
requirements.
EPA has determined that this rule does not include a Federal
mandate that may result in estimated costs of $100 million or more to
either State, local, or tribal governments in the aggregate. The rule
would not impose any federal intergovernmental mandate because it
imposes no enforceable duty upon State, tribal or local governments.
States, tribes and local governments have no compliance costs under
this rule. For the same reasons, EPA also has determined that this rule
contains no regulatory requirements that might significantly or
uniquely affect small governments. In addition, as discussed above, the
private sector is not expected to incur costs exceeding $100 million.
By these findings, EPA has fulfilled the requirement for analysis under
the Unfunded Mandates Reform Act.
D. Executive Order 12875: Enhancing the Intergovernmental Partnership
Under Executive Order 12875, EPA may not issue a regulation that is
not required by statute and that creates a mandate upon a State, local
or tribal government, unless the Federal government provides the funds
necessary to pay the direct compliance costs incurred by those
governments, or EPA consults with those governments. If EPA complies by
consulting, Executive Order 12875 requires EPA to provide to the Office
of Management and Budget a description of the extent of EPA's prior
consultation with representatives of affected State, local and tribal
governments, the nature of their concerns, copies of any written
communications from the governments, and a statement supporting the
need to issue the regulation. In addition, Executive Order 12875
requires EPA to develop an effective process permitting elected
officials and other representatives of State, local and tribal
governments ``to provide meaningful and timely input in the development
of regulatory proposals containing significant unfunded mandates.''
Today's rule does not create a mandate on State, local or tribal
governments. The rule does not impose any enforceable duties on these
entities.
[[Page 64402]]
It issues a final decision not to list wastes generated from the use of
14 chemicals as solvents as hazardous under the Resource Conservation
and Recovery Act (RCRA). Accordingly, the requirements of section 1(a)
of Executive Order 12875 do not apply to this rule.
E. Executive Order 13045: Protection of Children From Environmental
Health Risks and Safety Risks
Executive Order 13045: ``Protection of Children from Environmental
Health Risks and Safety Risks'' (62 FR 19885, April 23, 1997) applies
to any rule that: (1) is determined to be ``economically significant''
as defined under E.O. 12866, and (2) concerns an environmental health
or safety risk that EPA has reason to believe may have a
disproportionate effect on children. If the regulatory action meets
both criteria, the Agency must evaluate the environmental health or
safety effects of the planned rule on children, and explain why the
planned regulation is preferable to other potentially effective and
reasonably feasible alternatives considered by the Agency.
This final rule is not subject to the Executive Order because it is
not economically significant as defined in E.O. 12866, and because the
Agency does not have reason to believe the environmental health or
safety risks addressed by this action present a disproportionate risk
to children. The Agency performed a risk assessment to assist in its
determination whether to list or not to list the solvent wastes in this
final rule as hazardous waste. This risk assessment calculated the
potential risk resulting from the current management of these wastes to
individuals (including sensitive populations like children). The Agency
has determined that management of these solvent wastes as hazardous is
not required and that the environmental health risks or safety risks
addressed by this action do not have a disproportionate effect on
children.
F. Environmental Justice E.O. 12898
EPA is committed to addressing environmental justice concerns and
is assuming a leadership role in environmental justice initiatives to
enhance environmental quality for all residents of the United States.
The Agency's goals are to ensure that no segment of the population,
regardless of race, color, national origin, or income bears
disproportionately high and adverse human health and environmental
impacts as a result of EPA's policies, programs, and activities, and
that all people live in clean and sustainable communities. In response
to Executive Order 12898 and to concerns voiced by many groups outside
the Agency, EPA's Office of Solid Waste and Emergency Response formed
an Environmental Justice Task Force to analyze the array of
environmental justice issues specific to waste programs and to develop
an overall strategy to identify and address these issues (OSWER
Directive No. 9200.3-17). The Agency has determined that a hazardous
waste listing is not justified for the wastes examined in this rule. As
a result, no specific action is required under this rule. It is,
therefore, not expected to result in any disproportionately negative
impacts on minority or low income communities relative to affluent or
non-minority communities.
G. Paperwork Reduction Act
This rule does not contain any information collection requirements
subject to OMB review under the Paperwork Reduction Act of 1980, 44
U.S.C. 3501 et seq.
H. National Technology Transfer and Advancement Act
Section 12(d) of the National Technology Transfer and Advancement
Act of 1995 (``NTTAA''), Pub L. No. 104-113, Sec. 12(d) (15 U.S.C. 272
note) directs EPA to use voluntary consensus standards in its
regulatory activities unless to do so would be inconsistent with
applicable law or otherwise impractical. Voluntary consensus standards
are technical standards (e.g., materials specifications, test methods,
sampling procedures, and business practices) that are developed or
adopted by voluntary consensus standards bodies. The NTTAA directs EPA
to provide Congress, through OMB, explanations when the Agency decides
not to use available and applicable voluntary consensus standards. This
action does not involved technical standards. Therefore, EPA did not
consider the use of any voluntary consensus standards.
I. Executive Order 13084: Consultation and Coordination With Indian
Tribal Governments
Under Executive Order 13084, EPA may not issue a regulation that is
not required by statute, that significantly or uniquely affects the
communities of Indian tribal governments, and that imposes substantial
direct compliance costs on those communities, unless the Federal
government provides the funds necessary to pay the direct compliance
costs incurred by the tribal governments, or EPA consults with those
governments. If EPA complies by consulting, Executive Order 13084
requires EPA to provide to the Office of Management and Budget, in a
separately identified section of the preamble to the rule, a
description of the extent of EPA's prior consultation with
representatives of affected tribal governments, a summary of the nature
of their concerns, and a statement supporting the need to issue the
regulation. In addition, Executive Order 13084 requires EPA to develop
an effective process permitting elected officials and other
representatives of Indian tribal governments ``to provide meaningful
and timely input in the development of regulatory policies on matters
that significantly or uniquely affect their communities.''
Today's rule does not significantly or uniquely affect the
communities of Indian tribal governments. As mentioned above, no
specific action is required by this action. Today's rule does not
create a mandate on State, local or tribal governments. The rule does
not impose any enforceable duties on these entities. Accordingly, the
requirements of section 3(b) of Executive Order 13084 do not apply to
this rule.
J. Congressional Review Act
The Congressional Review Act, 5 U.S.C. 801 et seq., as added by the
Small Business Regulatory Enforcement Fairness Act of 1996, generally
provides that before a rule may take effect, the agency promulgating
the rule must submit a rule report, which includes a copy of the rule,
to each House of the Congress and to the Comptroller General of the
United States. EPA has submitted a report containing this rule and
other required information to the U.S. Senate, the U.S. House of
Representatives, and the Comptroller General of the United States prior
to publication of the rule in the Federal Register. This action is not
a ``major rule'' as defined by 5 U.S.C. 804(2).
List of Subjects in 40 CFR Part 261
Environmental protection, Hazardous materials, Waste treatment and
disposal, Recycling.
Dated: October 30, 1998.
Carol M. Browner,
Administrator.
[FR Doc. 98-30601 Filed 11-18-98; 8:45 am]
BILLING CODE 6560-50-P