ENVIRONMENTAL PROTECTION AGENCY 

40 CFR Part 261 

[EPA-HQ-RCRA–2003–0004; FRL–7587–7] 

RIN 2050–AE51 

Hazardous Waste Management System: Identification and Listing of Hazardous 

Waste: Conditional Exclusion from Hazardous Waste and Solid Waste for SolventContaminated Industrial Wipes 

AGENCY: Environmental Protection Agency 

ACTION: Notice of 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 two specific issues in light of the results of 

the revised risk analysis. 
2 

DATES: Comments must be received within [Insert date (60 days) after publication in 

the Federal Register.]

ADDRESSES: Submit your comments, identified by Docket ID No. EPA-HQRCRA-2003-0004 by one of the following methods: 

• 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. EPAHQ-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 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 www.regulations.gov or e-mail. The www.regulations.gov website is 
3 

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 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 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 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. 
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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, N.W., 

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: 

Industry Industry 

1. Printing manufacturing 9. Auto dealers (retail trade) 

2. Chemical and allied products manufacturing 10. Publishing (printed matter) 

3. Plastics and rubber products manufacturing 11. Business services 

4. Fabricated metal products manufacturing 12. Auto repair and maintenance 

5. Industrial machinery and equipment 

manufacturing 

13. Military bases 

6. Electronics and computers manufacturing 14. Solid waste services 

7. Transportation equipment manufacturing 15. Industrial launderers 

8. Furniture and fixture manufacturing 

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 applicability of this action to a particular entity or industry, consult 
5 

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 CDROM 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 
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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 TWO SPECIFIC ISSUES 

IV. CONCLUSION
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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 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 solventcontaminated 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 
8 

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 solventcontaminated 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 solventcontaminated wipes and industrial laundry sludge. 

B. November 2003 Proposed Rule Standard 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. 
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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 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 nonhazardous 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. 
10 

 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 proposed revisions 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 
11 

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

 

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. 
12 

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 solvents2

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. 

 After identifying the remaining 20 solvents3

 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 

 

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 

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). 
13 

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 solventcontaminated 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. 

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 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, and the 50th percentile 
14 

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). 

 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 solventcontaminated 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 

 

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 40CFR 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. 

Deleted: to ensure 
15 

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 
16 

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 riskbased 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.pdfwhich 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 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 
17 

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 

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 noncancer 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 
18 

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 RBMLL 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 (EPA-HQ-RCRA-2003-0004). 

 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 1x10-5 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 
19 

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

• In the original risk screening analysis, we did not consider risks from lined 

landfills. The revised risk analysis does consider risks from composite lined nonhazardous 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 

 

6

 Solvents in 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 
20 

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 THREE 

MANAGEMENT APPROACHES 

 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 solventcontaminated 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 
21 

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 landfill7

 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 establish conditions that allow all solventcontaminated 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 §258.40(a)(2) and (b). This 

 

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 1×10−7

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. 
22 

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. 

 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 RBMLL 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 solventcontaminated 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 

Deleted: Because of this risk concern, 

we are considering prohibiting the 

disposal of tetrachloroethylene, either on 

solvent-contaminated wipes or in laundry 

sludge that exhibits the 

tetrachloroethylene toxicity characteristic 

(TC) in nonhazardous waste landfills

Deleted: Another approach could be 

eliminating wipes contaminated with 

tetrachloroethylene from the scope of the 

final exclusions for solvent-contaminated 

wipes, or to not include 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.¶
23 

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: __________________ 

_______________________ 

Mathy Stanislaus 

Assistant Administrator, Office of Solid Waste and Emergency Response