[Federal Register: October 27, 2009 (Volume 74, Number 206)]
[Proposed Rules]
[Page 55163-55168]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr27oc09-30]
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ENVIRONMENTAL PROTECTION AGENCY
40 CFR Part 261
[EPA-HQ-RCRA-2003-0004; FRL-8973-2]
RIN 2050-AE51
Hazardous Waste Management System: Identification and Listing of
Hazardous Waste: Conditional Exclusion From Hazardous Waste and Solid
Waste for Solvent-Contaminated Industrial Wipes
AGENCY: Environmental Protection Agency.
ACTION: Data availability, management approaches, and request for
comment.
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SUMMARY: This notice of data availability (NODA) invites comments on a
revised risk analysis supporting the Environmental Protection Agency's
(EPA) proposed revisions to the Resource Conservation Recovery Act
(RCRA) hazardous waste regulations governing the management of solvent-
contaminated wipes. The revised analysis addresses public comments
received on the risk screening analysis conducted on EPA's 2003 Federal
Register proposal to exclude solvent-contaminated wipes from the RCRA
definitions of solid and hazardous waste. To address these comments,
EPA updated the data, models, and approach used in the risk analysis
and then had the product peer reviewed by outside experts. The revised
risk analysis, as well as the peer review comments and our response to
those comments are available in the docket for this NODA. The NODA also
invites comment on specific issues in light of the results of the
revised risk analysis.
DATES: Comments must be received within December 28, 2009.
ADDRESSES: Submit your comments, identified by Docket ID No. EPA-HQ-
RCRA-2003-0004 by one of the following methods:
http://www.regulations.gov: Follow the on-line
instructions for submitting comments.
E-mail: rcra-docket@epa.gov, Attention Docket No. EPA-HQ-
RCRA-2003-0004.
Fax: 202-566-9744, Attention Docket No. EPA-HQ-RCRA-2003-
0004.
Mail: Environmental Protection Agency, EPA Docket Center
(EPA/DC), Resource Conservation and Recovery Act (RCRA) Docket, 2822T,
1200 Pennsylvania Avenue, NW., Washington, DC 20460, Attention Docket
No. EPA-HQ-RCRA-2003-0004. Please include 2 copies.
Hand Delivery: Public Reading Room, EPA West, Room 3334,
1301 Constitution Ave., NW., Washington, DC, Attention Docket No. EPA-
HQ-RCRA-2003-0004. Such deliveries are only accepted during the
docket's normal hours, and special arrangements should be made for
deliveries of boxed information.
Instructions: Direct your comments to Docket ID No. EPA-HQ-RCRA-
2003-0004. EPA's policy is that all comments received will be included
in the public docket without change and may be made available online at
http://www.regulations.gov, including any personal information
provided, unless the comment includes information claimed to be
Confidential Business Information (CBI) or other information whose
disclosure is restricted by statute. Do not send information you
consider CBI or that is otherwise protected through http://
www.regulations.gov or e-mail. The http://www.regulations.gov Web site
is an ``anonymous access'' system, which means EPA will not know your
identity or contact information unless you provide it in the body of
your comment. If you send an e-mail comment direct to EPA without going
through http://www.regulations.gov, your e-mail address will be
automatically captured and included as part of the comment that is
placed in the public docket and made available on the Internet. If you
send an electronic comment, EPA recommends that you include your name
and other contact information in the body of your comment and with any
disk or CD-ROM you send. If EPA cannot read your comment because of
technical difficulties and cannot contact you for clarification, EPA
may not be able to consider your comment. Electronic files should avoid
the use of special characters, any form of encryption, and be free of
any defects or viruses. For more information about EPA's public docket,
visit the EPA Docket Center homepage at http://www.epa.gov/epahome/
dockets.htm.
Docket: All documents in the docket are listed in the http://
www.regulations.gov index. Although listed in the index, some
information is not publicly available, e.g., CBI or other information
whose disclosure is restricted by statute. Certain other material, such
as copyrighted material, will be publicly available only in hard copy.
Publicly available docket materials are available either electronically
in http://www.regulations.gov or in hard copy at the Resource
Conservation and Recovery Act (RCRA) Docket, EPA/DC, EPA West, Room
3334, 1301 Constitution Ave., NW., Washington, DC. The Public Reading
Room is open from 8:30 a.m. to 4:30 p.m., Monday through Friday,
excluding legal holidays. The telephone number for the Public Reading
Room is (202) 566-1744, and the telephone number for the RCRA Docket is
(202) 566-0270.
FOR FURTHER INFORMATION CONTACT: Teena Wooten, Office of Resource
Conservation and Recovery (ORCR), (703) 308-8751, wooten.teena@epa.gov.
Direct mail inquiries to the U.S. Environmental Protection Agency,
Office of Resource Conservation and Recovery, (Mailstop 5304P), 1200
Pennsylvania Avenue, NW., Washington, DC 20460.
SUPPLEMENTARY INFORMATION:
I. General Information
A. Does this Action Apply to Me?
This action may affect up to 164,000 entities in at least 15
industries involved in the use and handling of solvent-contaminated
wipes. These industries include, but are not limited to:
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Industry
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1. Printing manufacturing.
2. Chemical and allied products manufacturing.
3. Plastics and rubber products manufacturing.
4. Fabricated metal products manufacturing.
5. Industrial machinery and equipment manufacturing.
6. Electronics and computers manufacturing.
7. Transportation equipment manufacturing.
8. Furniture and fixture manufacturing.
9. Auto dealers (retail trade).
10. Publishing (printed matter).
11. Business services.
12. Auto repair and maintenance.
13. Military bases.
14. Solid waste services.
15. Industrial launderers.
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This list is not intended to be an exhaustive list, but rather
provides a guide for readers regarding entities likely to be covered by
this action. This list includes the types of entities that EPA is now
aware of that could potentially be covered by this action. Other types
of entities not listed above could also be addressed by this action. If
you have any questions about the
[[Page 55164]]
applicability of this action to a particular entity or industry,
consult the individual listed above in the FOR FURTHER INFORMATION
CONTACT Section.
B. What Should I Consider as I Prepare My Comments for EPA?
1. Submitting CBI. Do not send CBI information to EPA through
http://www.regulations.gov or e-mail. Clearly mark the part or all the
information that you claim to be CBI. For CBI information on a disk or
CD-ROM that you mail to EPA, mark the disk or CD-ROM as CBI and then
identify electronically within the disk or CD-ROM the specific
information that is claimed as CBI. As well as one complete version of
the comment that includes information claimed as CBI, send a copy of
the comment that does not contain the information claimed as CBI for
inclusion in the public docket. Information so marked will not be
disclosed, except under procedures set forth in 40 CFR part 2.
2. Tips for Preparing Your Comments. When sending comments,
remember to:
Identify the rulemaking by docket number and other
identifying information (subject heading, Federal Register date and
page number).
Follow directions--The agency may ask you to respond to
specific questions or organize comments by referencing a Code of
Federal Regulations (CFR) part or section number.
Explain why you agree or disagree, suggest alternatives,
and substitute language for your requested changes.
Describe any assumptions and provide any technical
information or data that you used.
If you estimate potential costs or burdens, explain how
you arrived at your estimate in enough detail to allow reproduction.
Provide specific examples to explain your concerns, and
suggest alternatives.
Explain your views as clearly as possible.
Make sure to send your comments by the comment period
deadline identified.
The contents of this notice are listed in the following outline:
I. Background
A. Introduction
B. November 2003 Proposed Rule Standards and Approach
C. Comments on the 2003 Proposal
II. Methodology and Results of the Revised Risk Analysis
A. Introduction
B. Were the Documents Peer Reviewed Before Issuing this Notice?
C. How were the Landfill Loadings for Solvent-Contaminated Wipes
Determined?
D. How were the Risk-Based Mass Loadings Calculated?
E. How were the Risk-Based Mass Loadings Compared to the
Solvent-Quantity Loadings?
F. What are the Results for the Comparison of the Loading
Estimates?
G. Request for Comment
III. Discussion and Request for Comment on Management Approaches and
Risk Analysis Findings
IV. Conclusion
I. Background
A. Introduction
A wide variety of industries use wipes (i.e., rags, shop towels,
disposable wipes and paper towels, collectively called ``wipes'') for
cleaning and degreasing. The wipes are handled in various ways. For
example, wipes may be used once or several times before they are thrown
away, while other wipes are used, laundered, and reused multiple times.
During cleaning and degreasing operations, these wipes may become
contaminated with solvents, as well as with other materials (e.g.,
paints, varnishes, waxes, metal shavings, inks, dirt). When discarded,
spent wipes are considered hazardous waste under the Federal hazardous
waste regulations if the wipes exhibit a hazardous waste characteristic
under 40 CFR part 261, subpart C or contain a solvent listed in 40 CFR
261.31 (that is, the solvents included in RCRA waste codes F001 through
F005).
Members of the regulated community petitioned EPA to remove
solvent-contaminated wipes from the hazardous waste regulations. The
petitioners argued that when small amounts of solvent are used on each
wipe, minimal risk occurs from the disposal of such wipes in municipal
solid waste landfills (MSWLF). Thus, they viewed the required disposal
of the solvent-contaminated wipes in RCRA Subtitle C hazardous waste
facilities as overregulation. Industrial laundries presented similar
arguments and requested that the solvent-contaminated wipes they wash
before returning them to their customers for reuse be excluded from the
definition of solid waste. After a review of the petitions, subsequent
industry requests and information, and internal EPA analysis, the
Agency decided to propose exclusions from the RCRA definition of solid
waste for solvent-contaminated wipes sent to a laundry or dry cleaner
and from the definition of hazardous waste for solvent-contaminated
wipes sent to a landfill or combustion facility, provided certain
conditions were met. We published the proposed changes in the November
20, 2003, Federal Register (68 FR 65586). The result of this proposal,
if finalized, would reduce the regulatory burden on users and handlers
of solvent-contaminated wipes. In support of the proposed regulatory
change, we completed a risk screening analysis to evaluate the
potential risk at MSWLFs from the disposal of solvent-contaminated
wipes and industrial laundry sludge.
B. November 2003 Proposed Rule Standards and Approach
To evaluate the appropriate regulatory status for solvent-
contaminated wipes, we considered the risks to the environment and
public health from the management of solvent-contaminated wipes and
wastewater treatment sludge from laundries (laundry sludge) in MSWLFs.
This was done by conducting a screening analysis to determine the
constituent-specific risks from landfilling wipes and laundry sludge
contaminated with the F001-F005 listed (40 CFR 261.31) spent solvents.
Then we estimated the risks from exposure to the 30 F001-F005 listed
solvents potentially used on wipes, assuming disposal in an unlined
MSWLF. Specifically, we looked at potential risks from inhalation of
the spent solvents volatilizing from the landfill, from ingestion of
groundwater contaminated by the spent solvents leaching from the
landfill, and from inhalation of the spent solvent vapors released from
contaminated groundwater during showering and other such uses. Section
V of the Technical Background Document for the proposed rule [Docket
EPA-HQ-RCRA-2003-0004] provides details on the risk screening analysis
conducted for the 2003 proposed rule.
C. Comments on the 2003 Proposal
During the comment period on the proposed rule, we received
substantive comments on the risk screening analysis and solvent loading
calculations from 23 commenters. In addition to public review and
comment, we received comments from outside peer reviewers. Both the
public and the peer reviewers questioned the validity of the risk
screening analysis and the modeling assumptions. These comments are
available in EPA's Docket No. EPA-HQ-RCRA-2003-0004.
II. Methodology and Results of the Revised Risk Analysis
A. Introduction
In response to the comments received from the peer reviewers and
the public on the risk screening analysis used to support the proposed
rule, we decided to revisit our risk analysis. Based on this
[[Page 55165]]
review, we determined that a more robust risk analysis was required to
adequately determine the potential risk from disposal of solvent-
contaminated wipes and laundry sludge in MSWLFs, also referred to in
this NODA as landfills or non-hazardous waste landfills. We have thus
completed a revised risk analysis which is more robust and more
sophisticated than the original risk screening analysis. The revised
risk analysis includes updated data and information, a new model to
evaluate the behavior of solvents in a landfill, revised fate and
transport modeling, including additional probabilistic modeling,
uncertainty and sensitivity analyses, and an improved approach to
compare the solvent quantity estimates to the risk-based solvent
levels. Because so much of the revised risk analysis is new, we believe
it appropriate to make it available for public comment before making
decisions on the final rule.
The revised risk analysis estimates the amount of each F-listed
solvent that is present in solvent-contaminated wipes and laundry
sludge disposed of in MSWLFs. We compared these amounts to the
quantities of spent solvents that may be disposed of in MSWLFs without
presenting unacceptable risks to human health and the environment
(risk-based mass loadings). The revised risk analysis consists of three
separate documents, which are described generally in this NODA. The
documents are:
--``Landfill Loadings Calculations for Disposed Solvent-Contaminated
Wipes and Laundry Sludge Managed in Municipal Landfills''
--``Risk-Based Mass Loading Limits for Solvents in Disposed Wipes and
Laundry Sludges Managed in Municipal Landfills''
--``F001-F005 Solvent-Contaminated Wipes and Laundry Sludge: Comparison
of Landfill Loading Calculations and Risk-Based Mass Loading Limits''
For more details about the revised risk analysis, please see the above
documents in the Docket (EPA-HQ-RCRA-2003-0004).
The discussion below summarizes our revised risk analysis for
disposal of the solvent-contaminated wipes and laundry sludge in
landfills.
B. Were the Documents Peer Reviewed before Issuing this Notice?
The revised risk analysis will be used to support EPA's rulemaking
to the RCRA hazardous waste regulations governing the management of
solvent-contaminated wipes. Under our peer review policy, risk analyses
used to support rulemaking decisions are influential scientific
information. Therefore, we conducted an external peer review in
accordance with both EPA's peer review policy and the Office of
Management and Budget's (OMB's) Final Information Quality Bulletin for
Peer Review. We asked the peer reviewers to conduct a comprehensive
review of the risk analysis. The peer reviewers were asked to respond
to a set of questions, which are included in the public docket for this
NODA addressing the technical basis of the approaches we used and to
prepare a report highlighting their comments and recommendations. The
peer reviewers suggested clarifications in several sections of the
``Landfill Loadings Calculations for Disposed Solvent-Contaminated
Wipes and Laundry Sludge Managed in Municipal Landfills'' document. One
reviewer questioned the method chosen to determine the uncertainty/
variability distribution, while two reviewers asked for more
information on determining the number of generators using wipes. The
reviewers also suggested that EPA review its discussion on sensitivity
analysis. For the ``Risk-Based Mass Loading Limits for Solvents in
Disposed Wipes and Laundry Sludges Managed in Municipal Landfills''
document, the reviewers recommended more data and discussion on the
model methodology and results. EPA revised these documents
incorporating the peer reviewers' comments, where necessary and
appropriate. The docket contains the individual peer reviewer reports,
EPA's response to the peer reviewers' comments, and supporting
documents for the peer reviews.\1\ For more information about the peer
review process, see EPA's Peer Review Handbook at http://www.epa.gov/
iris/Peer_Review_Handbook_2006_3rd_edition.pdf.
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\1\ The ``F001-F005 Solvent-Contaminated Wipes and Laundry
Sludge: Comparison of Landfill Loading Calculations and Risk-Based
Mass Loading Limits'' document was developed after completion of the
peer reviews.
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C. How were the Landfill Loadings for Solvent-Contaminated Wipes
Determined?
We began the evaluation by looking at the 30 solvents listed in 40
CFR 261.31 (F001-F005). Through literature review and site visits, we
eliminated 10 of these 30 solvents \2\ from the analysis. Of the 10
eliminated solvents, 5 are ozone-depleting or present other serious
hazards and are therefore banned or restricted from use. The other 5
solvents eliminated from the analysis may have been used on wipes in
the past; however, our research found that these solvents are currently
not used or are used only in limited quantities in conjunction with
wipes. The Agency solicits comment on this finding.
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\2\ Carbon tetrachloride, 1,1,1-Trichloroethane,
Trichlorofluoromethane, Dichlorodifluoromethane, 1,1,2-
Trichlorotrifluorethane (ozone depleting substances), Carbon
disulfide, ethyl ether, Nitrobenzene, 2-Nirtopropane, Pyridine (not
know to be used as solvents in wipes applications). For the
discussion on the solvents, see the ``Landfill Loadings Calculations
for Disposed Solvent-Contaminated Wipes and Laundry Sludge Managed
in Municipal Landfills'' Section 1.2.1 and 1.2.2.
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After identifying the remaining 20 solvents \3\ to evaluate, we
used both deterministic (point-value) and Monte Carlo (probabilistic)
methods in the analysis. We estimated the number of generators and the
number of wipes used by those generators. Few generators have the same
solvent use practices or use the same number of wipes. To account for
these differences, our revised risk analysis included an assessment of
the uncertainty using empirical data-based probability distributions in
a Monte Carlo analysis. We conducted a separate sensitivity analysis to
assess the influence that each input parameter has on the result. These
results identify the most and least influential assumptions. We
estimated the amount of solvent that could be on a wipe or in laundry
sludge before disposal and then estimated the number of generators
potentially disposing of solvent-contaminated wipes or laundry sludge
into a single MSWLF. Through our calculations, we derived estimated
landfill loadings for the solvents. The full report, ``Landfill
Loadings Calculations For Disposed Solvent-Contaminated Wipes and
Laundry Sludge Managed in Municipal Landfills'' describes the
assumptions made, methodologies used, and the results of the analysis.
The Docket (EPA-HQ-RCRA-2003-0004) for this NODA contains this
document.
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\3\ Acetone, benzene, butanol, chlorobenzene, cresols (total),
cyclohexanone, dichlorobenzene, 1, 2-ethoxyethanol, 2-ethyl acetate,
ethyl benzene, isobutanol, methanol, methyl ethyl ketone, methyl
isobutyl ketone, methylene chloride, tetrachloroethylene, toluene,
trichloroethane, 1,1,2-trichloroethylene, xylene (mixed isomers).
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D. How were the Risk-Based Mass Loadings Calculated?
We also developed a methodology to estimate the amount of hazardous
spent solvents that could be disposed of in MSWLFs (unlined and
composite lined), and be protective of human health and the environment
at the point of exposure. These ``allowable amounts'' are risk-based
mass loading rates expressed in kg of each spent solvent
[[Page 55166]]
that can be added to a landfill in a given year. These risk-based mass
loading rates were derived from modeling scenarios defined in terms of
the solvent, landfill type (e.g., lined or unlined), exposure pathway
(e.g., ambient air inhalation), contact media (e.g., groundwater), and
receptor (e.g., child or adult). Mass loading rates were estimated for
each solvent such that the exposure at the 50th and 90th percentiles of
the risk distribution would not exceed the identified risk target
criteria, if these materials were disposed of in a MSWLF. The 50th and
90th percentiles are typically used by the Agency to characterize risk.
The 90th percentile represents a ``high end'' estimate of individual
risk, while the 50th percentile results reflect the central tendency
estimate of the risk distribution.\4\ For this analysis, the risk
criteria were selected so that either 50 or 90 percent of the
hypothetical individuals living near a landfill will not be exposed to
solvent releases resulting in an excess lifetime cancer risk above 1
chance in 10,000 (10-4) through 1 chance in 1,000,000
(10-6).\5\ For noncancer health effects, we used a hazard
quotient (HQ) of one as our risk criterion (the noncancer HQ is defined
as the ratio of predicted intake levels to safe intake levels).
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\4\ Guidance for Risk Characterization, U.S. Environmental
Protection Agency, 1995.
\5\ These risk criteria are consistent with those discussed in
EPA's hazardous waste listing determination policy (see December 22,
1994; 59 FR 66072). Also see 40 CFR 300.430(e)(2)(i)(A)(2), which
establishes a cancer risk range of 10-4 to
10-6 in the National Oil and Hazardous Substances
Pollution Contingency Plan (NCP) for responding to releases of
hazardous substances under Superfund.
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We identified the following exposure pathways based on the
solubility and volatility of the 20 spent solvents included in the
analysis, as well as the operating practices of nonhazardous waste
landfills:
(1) Inhalation of ambient air containing spent solvents emitted
from the landfill at residential dwellings;
(2) Ingestion of spent solvents that leach from the landfill and
migrate through groundwater to residential drinking water wells;
(3) Inhalation of spent solvents during showering and bathing with
solvent-contaminated groundwater; and
(4) Dermal contact of spent solvents during showering and bathing
with solvent-contaminated groundwater.
A probabilistic approach was used to develop national mass loading
rates because landfills that receive solvent-contaminated wipes and
laundry sludge could be of varying geometry and located in many
different parts of the country. The approach primarily addresses the
variability in waste management practices (that is, unlined and
composite lined landfills), environmental settings, and exposure-
related parameters. We also developed a landfill source model to
simulate the solvent-specific air emissions and leachate releases from
landfills. The quantity of solvent releases to the air and groundwater
were then used as inputs to the air and groundwater fate and transport
models.
For each solvent, we calculated risk estimates assuming a unitized
mass loading rate (1 kg per year) for each liner type, exposure
pathway, and receptor, as well as for the combined exposures associated
with groundwater uses. The risk results provide insight into the
relative nature of exposures and potential risks that could be
associated with the solvent-contaminated wipes disposed of in MSWLFs.
For unlined landfills, the groundwater pathways were always
associated with the highest predicted risks at the 50th and 90th
percentiles of the distributions. For composite lined landfills,
groundwater exposures were associated with the highest risks at the
90th percentile, except for methylene chloride and methyl ethyl ketone,
which showed higher risks for the ambient air inhalation pathway. At
the 50th percentile, the highest predicted risks were associated with
the ambient air inhalation pathway for 16 of the 20 solvents; however,
for unlined landfill disposal, the predicted risks were associated more
with drinking water.
From this information, we developed solvent-specific risk-based
mass loading rates (in kg/yr) that could be disposed of in a MSWLF and
meet specific risk criteria and be protective of human health and the
environment. The risk-based mass loading rates do not provide direct
insight into the potential impacts associated with current management
practices. The full report, ``Risk-Based Mass Loading Limits for
Solvents in Disposed Wipes and Laundry Sludges Managed in Municipal
Landfills'' describes the assumptions made, methodologies used, and the
results of the analysis. The Docket for this NODA (EPA-HQ-RCRA-2003-
0004) contains this document.
E. How were the Risk-Based Mass Loadings Compared to the Solvent-
Quantity Loadings?
To perform a comparison, EPA evaluated a 90th percentile risk
criterion for the risk-based mass loading limit to be protective of 90
percent of hypothetically exposed individuals across all of the
landfill sites in the United States (Guidance for Risk
Characterization, U.S. Environmental Protection Agency, 1995;
accessible at http://www.epa.gov/OSA/spc/pdfs/rcguide.pdf, which states
that ``For the Agency's purposes, high end risk descriptors are
plausible estimates of the individual risk for those persons at the
upper end of the risk distribution,'' or conceptually, individuals with
``exposure above about the 90th percentile of the population
distribution''). As recommended in the Guidance, EPA also evaluated the
50th percentile results as the central tendency estimate of that risk
distribution. Thus, we compared the 90th percentile estimate of
landfill loading rates (ELLRs) to the 90th percentile of the risk-based
mass loading levels (RB-MLLs) to determine whether the ELLRs in
landfills that can be attributed to solvent-contaminated wipes and
laundry sludge exceeds the RB-MLLs that correspond to selected health-
based limits. A similar comparison was conducted at the 50th
percentile.
F. What are the Results for the Comparison of the Loading Estimates?
The results for both the ELLR and the RB-MLL are generated from a
probabilistic analysis. The results from these two separate
calculations are given by a distribution of values. The theoretical
risk distribution provides the basis for calculating risk-based mass
loading rates for any percentile of that distribution. Based on the
risk criteria that EPA evaluated for the wipes analysis, the RB-MLL was
identified at the 50th and 90th percentiles of the distribution. These
levels represent the allowable mass loading rate (in kg per year) for
management of solvent-containing wipes and laundry sludges in a MSWLFs
anywhere in the country in any given year.
The comparisons of the ELLRs and RB-MLLs are expressed as ratios,
i.e., the 90th percentile ELLRs (kg solvent per year) are divided by
the 90th percentile RB-MLLs (kg solvent per year) for a specific
solvent to yield ratios. The ELLR is an estimate of the mass loading
into the landfill and the RB-MLL is an estimate of the mass loading
that would correspond to an exposure equivalent to the chosen risk
criterion, or risk ``target.'' Therefore, if the ratio exceeds one,
this indicates the degree to which the ELLR exceeds the evaluation
criteria used to establish the RB-MLLs (i.e., a cancer risk of 1 x
10-5 and an HQ of 1 for noncarcinogenic risk).
The comparison of the 90th percentile values of the ELLRs and the
RB-MLLs
[[Page 55167]]
indicates that 8 of the 20 spent solvents could pose potential risks
above EPA's evaluated criteria at some risk levels for unlined
landfills. The 90th percentile risks for benzene (using the high end
cancer risk value only), 1,1,2-trichloroethane, methylene chloride,
tetrachloroethylene, and trichloroethylene exceeded the 10-5
cancer risk criteria. The 90th percentile risks for chlorobenzene,
toluene, and xylenes exceeded the criteria for non-cancer health
effects (HQ = 1). As expected, the predicted risks for the unlined
landfill analysis were always greater than those for the composite-
lined landfill analysis. Using the comparison of the 90th percentile
results, the potential risks from all solvents examined in the
composite-liner scenario, except for tetrachloroethylene, were well
below (generally <0.1) the health-based criteria used in this analysis.
The value for tetrachloroethylene was 1.1 using the higher end cancer
risk value and 0.9 using the lower end cancer risk value. For a more
detailed explanation of how the ELLR and RB-MLL were compared, see the
``F001-F005 Solvent-Contaminated Wipes and Laundry Sludge: Comparison
of Landfill Loading Calculations and Risk Based Mass Loading Limits''
document in the docket for this NODA.
A comparison of the ELLR and RB-MLL central tendency values (50th
percentiles), showed that tetrachloroethylene is the only solvent in
the unlined landfill scenario that produced a ratio of ELLR to RB-MLL
greater than one (using a cancer risk of 1 x 10-5 and an HQ
of 1) and this value was 1.4 using the higher end cancer risk value;
using the lower end cancer risk value, the ratio was 1.2. For the
composite liner scenario, all ratios of the 50th percentile ELLRs and
RB-MLLs are well below one using these risk criteria.
The ratios from a comparison of the ELLRs and the RB-MLLs for the
constituents with carcinogenic risk would change if the RB-MLLs were
calculated using a risk criterion different from the 1 x
10-5 criterion. If a target risk level of 1 x
10-4 were used for calculating the RB-MLLs, the carcinogenic
risk for the carcinogens (1,1,2-trichloroethane, benzene, methylene
chloride, tetrachloroethylene, and trichloroethylene) would be lower by
a factor of ten. Alternatively, if a target risk level of 1 x
10-6 were used, the cancer risks for these constituents
would be higher by a factor of ten. A comparison of the ELLR and RB-MLL
values using the 10-4 risk criterion for the no-liner
scenario would have the effect of lowering the ratios; however, the
ratios of 7 of the 8 solvents of potential concern would remain above
one at the 90th percentile (the ratio for benzene would be less than
one). Using the 10-4 criterion at the 50th percentile, the
ratios for all the solvents would be below one. Using the
10-6 risk criterion would have the effect of raising the
ratios in the unlined landfill scenario for carcinogens, such that the
ratios for all these 8 solvents for the 90th percentile results would
exceed one by a wider margin. Using the 10-6 risk criterion,
the ratios from the 50th percentile results would increase for the
carcinogenic solvents, such that the ratios for tetrachloroethylene and
trichloroethylene would exceed one at the 50th percentiles.
For the composite-liner scenario, the ratios for all solvents would
be below one (including tetrachloroethylene) at both the 90th and 50th
percentiles using the 10-4 risk criterion. Using the
10-6 criterion, the ratios for tetrachloroethylene and
trichloroethylene at the 90th percentile are above one.
These results differ from our original risk screening analysis for
the proposed rule in the following ways:
The number of solvents that show a potential risk for
disposal in an unlined landfill in our risk screening analysis
increased by 2 in the revised analysis and the solvents indicating a
potential risk also changed.\6\
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\6\ Solvents in the proposal indicating a potential risk in
unlined landfill scenario: Methyl ethyl ketone, methyl isobutyl
ketone, nitrobenzene, pyridine, methylene chloride, 2-nitroproane.
Solvents from revised risk analysis indicating a potential risk in
unlined landfill scenario: benzene, 1,1,2-trichloroethane,
chlorobenzene, methylene chloride, tetrachloroethylene, toluene,
trichloroethylene, and xylene.
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In the original risk screening analysis, we did not
consider risks from lined landfills. The revised risk analysis does
consider risks from composite lined non-hazardous waste landfills.
In the original risk screening analysis, we did not
identify any solvents of concern from laundry sludge. Our revised risk
analysis indicates that tetrachloroethylene may be a concern in both
solvent-contaminated wipes and laundry sludge disposed of in unlined
and composite lined landfills.
G. Request for Comment
We are seeking comment on all aspects of the revised risk analysis
(landfill loading calculations, risk based mass loading levels,
comparison document). In particular, we are seeking comment on:
--The assumptions used;
--Whether the uncertainties are properly acknowledged and
mitigated, as appropriate;
--The data used;
--The methodology used; and
--How the agency should consider using the results of the revised
risk analysis in its decision-making.
III. Discussion and Request for Comment on Management Approaches and
Risk Analysis Findings
The Agency's November 2003 proposal allowed solvent-contaminated
wipes and laundry sludge that met certain conditions to be sent either
to a MSWLF or to another nonhazardous waste landfill that meets the
standards under 40 CFR part 257, subpart B. We did not discuss the
specific characteristics of MSWLFs receiving solvent-contaminated wipes
or laundry sludge, specifically whether the landfill would be unlined
or lined. Because our revised risk analysis indicates that a number of
solvents show a potential for risk in unlined landfills (using the 90th
percentile results and a risk criterion of 1 x 10-\5\ for
cancer risk), we are considering two additional approaches for managing
solvent-contaminated wipes and laundry sludge in landfills.
The first approach would allow the disposal of solvents not showing
a risk in any municipal landfill or nonhazardous waste landfill whether
lined or unlined. The solvents that indicated a potential risk if
disposed of in an unlined landfill \7\ could only be disposed in a
lined municipal landfill or lined non-hazardous waste landfill. This
could be accomplished by requiring disposal in a Subtitle D municipal
or industrial landfill unit subject to, or otherwise meeting, the
landfill requirements in 40 CFR 258.40(a)(2) and (b).8 9 The
second approach would be to
[[Page 55168]]
establish conditions that allow all solvent-contaminated wipes, no
matter which solvent they contain, except perhaps tetrachloroethylene,
to be sent to a Subtitle D municipal or industrial landfill unit
subject to, or otherwise meeting, the landfill requirements in Sec.
258.40(a)(2) and (b). This approach could be simpler since the
generator would not need to separate his wipes and send them to
separate disposal locations. We are requesting comment on these two
approaches.
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\7\ Benzene, 1,1,2-trichloroethane, chlorobenzene, methylene
chloride, toluene, trichloroethylene, and xylene.
\8\ 40 CFR 258.40(a)(2) states: ``With a composite liner, as
defined in paragraph (b) of this section and a leachate collection
system that is designed and constructed to maintain less than a 30-
cm depth of leachate over the liner. 40 CFR 258.40(b) states ``For
purposes of this section, composite liner means a system consisting
of two components; the upper component must consist of a minimum 30-
mil flexible membrane liner (FML), and the lower component must
consist of at least a two-foot layer of compacted soil with a
hydraulic conductivity of no more than 1 x 10-\7\cm/sec.
FML components consisting of high density polyethylene (HDPE) shall
be at least 60-mil thick. The FML component must be installed in
direct and uniform contact with the compacted soil component.''
\9\ Solvent-contaminated wipes, while not required, could also
be disposed of in a hazardous waste landfill meeting the landfill
requirements in 40 CFR 264.301 or 265.301.
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The risk analysis using 90th percentile results also indicates that
tetrachloroethylene has a risk potential in both unlined landfills and
composite lined landfills for both solvent-contaminated wipes and
laundry sludge (using a cancer risk criterion of 1 x
10-\5\). Using the higher end cancer risk value in our
analysis, the ratio of the ELLR to the RB-MLL for tetrachloroethylene
was 1.1, while using the lower end cancer risk value the ratio was 0.9.
If we rounded the numbers, the ratios would both be 1.0. Since we
generally used a conservative approach in the risk analysis, we are
asking for comment on whether our results represent a risk of concern.
Even though the risk may be borderline, we are considering
alternative management conditions for tetrachloroethylene to address
this potential risk. One approach is to prohibit disposal of
tetrachloroethylene, either on solvent-contaminated wipes or in laundry
sludge that exhibits the tetrachloroethylene toxicity characteristic
(TC) in nonhazardous waste landfills. Another approach could be
eliminating wipes contaminated with tetrachloroethylene from the scope
of the final exclusions for solvent-contaminated wipes, or eliminating
wipes contaminated with tetrachloroethylene that exhibit the TC in the
scope of the final exclusions for solvent-contaminated wipes. We are
requesting comment on these approaches or other possible alternatives.
IV. Conclusion
We will consider comments received on the revised risk analysis and
then modify the analysis as appropriate. The final risk analysis,
comments submitted in response to Section III of this notice, and
comments submitted in response to the November 2003 proposed rule will
be considered as we develop a final rule for the management of solvent-
contaminated wipes.
Readers should note that other than the specific issues identified
in this NODA, no other issues discussed in or related to the November
20, 2003, proposed rule are open for further comment and the Agency
will not respond to any comments received on any issues not identified
in this NODA.
Dated: October 15, 2009.
Mathy Stanislaus,
Assistant Administrator, Office of Solid Waste and Emergency Response.
[FR Doc. E9-25812 Filed 10-26-09; 8:45 am]
BILLING CODE 6560-50-P