Response to Comments on the 2003 

Proposal on the Landfill Loadings 

Calculations for

Solvent-Contaminated Wipes

December, 2011

Office of Resource Conservation and Recovery

U.S. Environmental Protection Agency

Prepared with the support of 

SAIC

12100 Sunset Hills Road

Reston, VA 20190

EPA Contract No.: EP-W-05-060
1

1. Introduction

In response to EPA’s 2003 proposed rule regarding the conditional exclusion of wipes (68 FR 

65586, November 20, 2003), EPA received many comments regarding the approach and 

assumptions used in estimating the quantity of solvent which may be disposed in a landfill, 

known as landfill loading. The scope of these comments included both the disposable wipes and 

reusable wipes analysis. The principal landfill loading assumptions for the 2003 proposed rule 

are in “Technical Background Document: Proposed Exclusions from the Definition of Hazardous 

Waste and Solid Waste for Solvent-Contaminated Industrial Wipes” (August 23, 2003), 

Document No. RCRA-2003-0004-0003.

Revisions to the landfill loading calculations were conducted to address these public comments. 

The revised landfill loading assumptions and results are presented in “Landfill Loadings 

Calculations For Disposed Solvent-Contaminated Wipes and Laundry Sludge Managed in 

Municipal Landfills,” January 2008 (this is referred to below as the ‘Landfill Loadings Report’

or ‘landfill loadings calculations’).

1 The comments identified below present comments related to 

this portion of the risk assessment. The relevant portions of the comments are presented 

verbatim; full comments are in the docket for the final rule. An explanation is included as to how 

the revised analysis addresses each comment.

The landfill loading calculations are used as inputs to the risk assessment in calculating risks to 

receptors. Comments relating to these other portions of the risk assessment, such as fate and 

transport assumptions, are not identified below; responses to other aspects of the risk assessment 

are provided in the document Response to Comments on the Solvent Contaminated Wipes 

Proposed 2003 Screening Risk Analysis, in the docket for the final rule.

2. Comments Primarily Addressing Differences in Assumptions Between the Disposable 

and Reusable Wipes Analyses

• Comment: Several commenters identified that EPA used different assumptions for disposable 

and reusable wipes (more high end assumptions for disposables than for laundry sludge). 

(See example comment No. 0283-INDA/SMART).

Response: The Landfill Loadings Report evaluates disposable and reusable wipes using 

probabilistic analyses (using a range of input values) and deterministic analyses (using 

average input values). In the probabilistic analyses, input parameters for each analysis are 

represented as distributions of available data rather than point values, eliminating the need to 

select single high end or central tendency input values for individual parameters. As a result, 

both the disposable and reusable wipes analyses in the revised Landfill Loadings Report use 

a similar set of input values with regard to high end values.

 1 EPA published a NODA in October 2009 that presented the January 2008 Landfill Loading Report for public 

comment. EPA subsequently revised the landfill loading analysis slightly to respond to comments on the January 

2008 document; this final document can be found in the docket for the final rule (see Landfill Loadings Calculations

For Solvent-Contaminated Wipes; January 2012). Responses to comments on the January 2008 document may be 

found in the docket in the document Response to Comments on the 2009 NODA on the Landfill Loadings 

Calculations for Solvent-Contaminated Wipes.
2

• Comment (0283 – INDA/SMART): Number of Generators Sending Their Wipes to a Single 

Landfill - EPA applied a “high-end” factor of 10 to the entire market of non-laundered wipes 

because the ratio of generators to land fills in the northeast U.S. is 10 times greater than the 

national average. Although the ratio of wipe generators to landfills in a geographic area 

applies equally for laundered wipes, EPA did not apply this factor of 10 at all in its analysis 

for laundered wipes.

Response: The revised landfill loading calculations account for the use of a single landfill for 

multiple wipes generators as well as use of a single landfill for more than one laundry. Refer 

to Sections 2.3.6 (for disposable wipes) and 3.3.6 (for laundries) of the Landfill Loadings

Report. The number of generators of disposable wipes using a single landfill continues to be 

greater than the number of laundries using a single landfill because there are a greater 

number of disposable wipes generators (approximately 15,000 nationwide) than industrial 

laundries processing reusable wipes (approximately 1,300 nationwide).

• Comment (0283 – INDA/SMART): Assumptions About the Wipe Market and Its Contribution 

to Solvent Loadings - In order to determine solvent loadings for solvent-soiled non-laundered 

wipes [SSNWs], EPA applied an arbitrary “high-end” parameter of 35 percent as the 

percentage of wipes assumed to contain one or more F-listed solvents,2 despite EPA’s own 

data indicating a 23.5% figure and industry-supplied data indicating that the actual figure is 

14%.3 In contrast, EPA used an average-sized (and supposedly “central tendency”) laundry 

in analyzing solvent loadings from laundry sludge, employing a figure that is substantially 

smaller than the actual “average size” per EPA’s own data. Moreover, EPA ignored largesized laundry data even though (i) about 80% of shop towels are processed by “non-small” 

laundries, (ii) 55% of laundered wipes are processed by the largest 10% of laundries, and (iii) 

large laundries process about ten times as many printer wipes (the industry segment EPA 

focused on for estimating the percentage of SSNWs containing F- listed solvents) and other 

shop towels as average laundries.

Response: Differences in the number of high end or central tendency input parameters used 

for the disposable wipes and reusable wipes analyses are reduced through the use of a 

 2 EPA arbitrarily based this figure on (i) data from the printing industry indicating that approximately 25 percent of 

printers use F-listed solvents (rather than on the percent of wipes used by printers with F-listed solvents) and (ii) an 

unfounded “assumption” (again based on information from the printing industry) that TC solvents are used ten

percent of the time. It is unclear why a parameter that is supposed to represent the percent of wipes containing Flisted solvents also includes an arbitrary assumption regarding the percentage of non-listed TC solvents. Moreover, 

for purposes of its screening analysis, EPA has distinguished between printer wipes and non-printer wipes for other 

parameters due to EPA’s recognition that the practices of printers with respect to wipes differ from those of other 

wipe generators. See Technical Background Document, at 100-101. EPA has not explained why it failed to do so 

here.

3 See Economics Background Document, at 13 (259 million non-laundered wipes potentially affected by rule 

divided by 1.1 billion total non-laundered wipes sold, or 23.5%); Letter from Ralph Solarski, Kimberly-Clark 

Corporation, to Jim O’Leary, OSW, EPA, July 25, 1997 (RCRA Docket No. 0109) (industry survey evaluating 

percentage of non-laundered wipes that come into contact with hazardous solvents).
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probabilistic analysis. ‘High-end’ parameters are not used in either analysis except as part of 

a range which also includes less conservative values.

The Landfill Loadings Report no longer includes a separate factor (such as 35 percent) for 

estimating the percentage of wipes containing F-listed solvents. Instead, the number of 

facilities assumed to generate F-listed solvent-contaminated disposable wipes was estimated 

from the Economics Background Document (Estimate of National Economic Impact of 

Conditional Exclusion of Solvent Industrial Wipes from RCRA Hazardous Waste Regulation

(RCRA-2003-0004-0004), updated using 2002 data).

• Comment (0283 – INDA/SMART ): Amount of Solvent Partitioning to the Environment - As 

noted above, EPA unjustifiably made the “high-end” assumptions that (i) 100% of solvent on 

landfilled SSNWs partitions to the environment, and (ii) no evaporation occurs, despite 

expert peer review comments that the former assumption is unwarranted and documented 

evidence that evaporation does occur. In the following ways, EPA chose not to adopt a 

comparable “high-end” parameter approach for laundry sludge:

o After noting that it “did not consider [its laundry wastewater solvent concentrations] a 

high-end parameter,” EPA then assumed that only 8 to 37 percent of the 

concentrations of solvent in laundry wash water partitions to sludge. The rest is 

assumed to partition to water and air, i.e., to evaporate.

o EPA made the “central tendency” assumption of wastewater treatment by oil/water 

separation and settling, rather than by dissolved air-flotation (DAF), a less commonly 

used technology that would result in substantially more solvent partitioning to the 

sludge.

o EPA used “central tendency” assumptions regarding the amount of wastewater 

generated per pound of wipes washed. (See Technical Background Document, at 

130.)

Response: The Landfill Loadings Report continues to use assumptions that 100 percent of the 

solvent on disposable wipes leaving the generator enters the landfill (the related landfill risk 

assessment assesses how much of the solvent, once in the landfill, is available for release to 

the environment). For reusable wipes, the Landfill Loadings Report continues to use 

assumptions that less than 100 percent of the solvent present on wipes entering the laundry 

becomes part of the laundry sludge for disposal. The reason for using ‘100 percent’ for 

disposable wipes and ‘less than 100 percent for reusable wipes is two-fold. First, once 

leaving the generator, the reusable wipes go through an extra management step (i.e., the 

laundry) which the disposable wipes do not. Second, there are differences in the degree of 

data available to quantify these effects.

In assessing reusable wipes, the Landfill Loadings Report continues to use the assumptions

identified by the commenter that a portion of the solvent in laundry wastewater partitions to 

the sludge, and uses an average or ‘central tendency’ value of the quantity of wastewater 

generated. The Landfill Loadings Report is modified to incorporate data regarding the 
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frequency that each treatment technology is used (e.g., DAF versus non-DAF), which in turn 

affects the degree that a constituent partitions to air/ water/ sludge.

With regard to disposable wipes, the Landfill Loadings Report does account for evaporation 

during use and conservatively estimates solvent removal following use, using data in EPA 

(1997)4 to estimate these effects when solvent application rates are available. Refer to 

Section 2.3.2 of the Landfill Loadings Report. Evaporation data to simulate evaporation 

following use at the generator site were available from Kimberly-Clark Corporation’s 

petition (Document No. RCRA-2003-0004-0016) but were not used; the EPA (1997) data 

assess similar removal processes and were used preferentially. Evaporation following use, 

but prior to disposal in a landfill (e.g., in transit), is not assessed in the Landfill Loadings 

Report for either disposable or reusable wipes. This is primarily due to a lack of data to 

quantify this effect.

3. Comments Primarily Addressing Assumptions for Disposable Wipes 

• Comment (0288-ETC): The Amount of Solvent Assumed on the Wipe is Underestimated.

EPA’s Risk Assessment assumes 10.48 grams of solvent on a given wipe, which amounts to 

a ratio of 1:1 solvent to wipe. Yet in Document-0003 the quantity of solvent can be as high as 

7:1 and typically can be on the order of 3:1. Using a 3:1 ratio yields a weight of 31.4 grams 

of solvent. Removal efficiencies cited in Document-0003 page 65 vary greatly, and for 

techniques other than centrifuging, range from 3.5% to 24%. Given that there is no 

performance standard mandated by the proposed rule for the “no free liquids” criterion, EPA 

must assume removal efficiencies on the lower end of this range, since these would be 

allowable under the rule. The wide variation in data is indicative of the fact that worker 

practices vary greatly and that lower removal efficiencies are very commonplace. Therefore, 

assuming 5% removal efficiency, a valid assumption given the data on page 65 of Document0003, the amount of solvent left on the 3:1 solvent wipe is 29.8 grams. For the 7:1 case, the 

amount of solvent remaining would be 70 grams.

(Comment continued) Other sources in the record also indicate comparable amounts of 

solvent per wipe following “extraction.” For example, page 4 of Document-0040 indicates 

these same amounts of solvent. Document-0127 indicates that after hand wringing a range of 

40.56 grams to 75.79 grams remained on wipes, which were hand wrung to the “one drop 

criterion.” This document was a study in which 34 replicates were done, meaning that it is 

statistically reliable. EPA is considering allowing hand wringing as an acceptable extraction 

technique to satisfy the “no free liquid” criterion. Document-0012 page 3-33 which assesses 

shop towel usage in the automotive and printing industries cites typical solvent remaining on 

a wipe as 0.031 lbs to 0.065 lbs, or 14.1 to 29.5 grams, based on an evaluation of 599,000 

towels.

(Comment continued) Clearly, unless EPA is mandating the use of centrifuge technology to 

satisfy the “no free liquids” criterion, actual amounts of solvent remaining on an “extracted” 

wipe are far in excess of the 10.48 grams of solvent assumed in the Risk Assessment. Given 

 4 U.S. EPA, 1997. Use and Management Practices of Solvent Contaminated Industrial Shop Towels. Final 

Document. Exhibits 1-3a and 1-3b.
5

that the rule imposes no controls on how extractions are performed, EPA should use the 

worse case supported by the record and assume 75.8 grams in the Risk Assessment. There is 

clearly no basis to assume 10.48 grams as EPA has done. This means that the risk results are 

understated by at least a factor of 7 due to this issue alone. The AMEC Report attached also 

cites this issue and identified a factor of 8 (see Table 2 of AMEC Report).

(Comment continued) EPA has specified in the proposed rule a condition that the wipe must 

contain less than 5 grams of solvent to be disposed in an MSW landfill. EPA specifies that 

generators must put their wipes through an extraction process capable of meeting the less 

than 5 grams solvent condition. However, a review of removal efficiency data in the docket, 

particularly that summarized in Table 10, page 65 of Document-0003 indicates that no 

extraction technology can be routinely relied upon to yield less than 5 grams, with the 

possible exception of centrifuging which EPA is not mandating. As described above, the 

more commonly applied techniques of hand wringing or use of a screen bottom drum will 

still result in as high as 75 grams of solvent still left on a wipe. EPA has to recognize the 

limitations of the extraction techniques and assume that the 5 gram criterion will not be met 

for the purposes of the risk assessment. Unless a means such as the graduated dispenser that 

places a maximum of 5 grams on the wipe to begin with is used, EPA has to assume that the 

wipe will contain much higher amounts of solvent than was modeled in this risk assessment.

(Comment continued) In Document-0003, another risk assessment summary is provided. On 

page 102 the document states that a 25 grams assumption was used for printer facilities and 

12.5 grams was used for non-printer facilities. If this is the case, this approach is also not 

acceptable because the other records in the docket show that other types of facilities besides 

printers can have high solvent weights applied to the wipes. There is nothing to suggest, for 

example, that automobile manufacturers, aerospace plants and furniture plants limit their 

wipe content to 12.5 grams. The risk must be modeled based on the maximum level expected 

following extraction, other than centrifuge, which is 75 grams. Note again the study that 

showed 40.6 to 75.8 grams left on a wipe following hand wringing (Document- 0127). The 

assumption of 25 grams is therefore not representative of real disposal conditions, unless the 

rule were to mandate centrifuging of wipes prior to disposal.

Response: The quantity of solvent assumed to be present on the wipes was modified in the 

landfill loadings calculations. Data were obtained from several of the resources present in the 

RCRA-2003-0004 docket, including Document No. 0127 identified by the commenter, to 

estimate the quantity of solvent remaining on a wipe when disposed. (However, data from 

Document No. 0012 identified by the commenter were not used because the quantities in this 

document represented total contaminant load, which include non-solvent contaminants such 

as dirt and ink, and not just solvent.) These data were used to develop a range in the 

quantities of solvent loadings on disposed wipes; these data are presented in Section 2.3.2 of 

the Landfill Loadings Report. In many cases these quantities are higher than five or ten 

grams per wipe. Different estimates were developed for different industries, such as printers

and auto repair, as data were available. The high end of the ranges (e.g., 70 grams), as 

suggested by the commenter, were not used because such a result would represent a high end 

input parameter and would bias the results, particularly if combined with other high end 

parameters. Instead, the range of these and other input parameters were used in a 
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probabilistic analysis, from which high end landfill loadings may be selected from an 

appropriate percentile (e.g., 90th percentile).

Some of the data used in developing these ‘per wipe’ estimates were developed from solvent 

application data, rather than measurements following use. In such cases, the application rate 

was used as a starting point in estimating the quantity of solvent remaining on the wipe; an 

allowance was made for evaporation and solvent removal (e.g., hand wringing) following use 

but before disposal. As suggested by the commenter, data for solvent removal was obtained 

from EPA (1997);

5 see Section 2.3.2 of the Landfill Loading Report.

• Comment (0288-ETC): The Wipe Usage Assumptions Are Inconsistent With Actual Industry 

Usage. The Risk Assessment assumes 120 wipes per day for LQGs and 30 wipes per day for 

SQGs. Yet Table 5 (page 27) of Document-0003 indicates wipe usage rates of 400 to 1000 

per day for many LQGs (see printing and aerospace sectors), “several hundred” per day for 

automobile manufacturers, and 50 to 100 wipes per day for a typical auto body repair shop. 

The Risk Assessment should therefore assume 1000 wipes per day for LQGs and 100 per day 

for SQGs. This means that the risk assessment is understates risk for LQG by a factor of 8.3 

and by a factor of 3.3 for SQGs.

EPA must assume the maximum usage rate of wipes, since this proposed rule would exempt 

all wipes from RCRA control. Without RCRA control, it is prudent to assume that wipe 

usage will actually increase, as the waste minimization measures promoted under RCRA 

control will cease to be urgent goals of generators. Also, EPA must assume some additional 

margin for economic growth. Therefore, it is more protective and valid to assume the high 

end of 1000 wipes per day for LQGs and 100 wipes per day for SQGs.

The AMEC report identifies a factor of 4.5 for this wipe usage rate, which would be in the 

midpoint of the estimate above (see Table 2 in the attached AMEC Report). This further 

supports that the risk results need to be adjusted upward.

Response: The landfill loadings calculations include the number of wipes used per year per 

generator. Rather than using a fixed value, the Landfill Loading Report used a range of 

values to correspond to the range of usage rates by sites. In addition, different usage rates 

were prepared for different generator types. This is discussed in Section 2.3.1 of the Landfill 

Loadings Report. For example, printing facilities were assumed to use disposable wipes at 

rates ranging from 1,000 to 600,000 wipes per year (average of 134,000 wipes per year). This 

corresponds to approximately 3 to 2,000 wipes per day (average of 450 wipes per day) for 

the printing industry. Using the range of wipe usage rates provides a result which reflects the 

variability in the rate of wipe use.

These usage rates were based on data in the record, such as those sources cited by the 

commenter. The data were not adjusted to account for the factors cited by the commenter, 

such as waste minimization or economic growth, because such adjustments would be too 

speculative.

 5 U.S. EPA, 1997. Use and Management Practices of Solvent Contaminated Industrial Shop Towels. Final 

Document. Exhibits 1-3a and 1-3b.
7

• Comment (0288-ETC): The assumption that a given landfill accepts only a single solvent on 

each wipe from one source is also flawed and grossly understates risk. In reality, a landfill in 

any given location would most likely accept wipes from many industrial and commercial 

sources. EPA notes in Document-0003 that there are over 200,000 facilities using solvent 

wipes in 13 major industry sectors. There clearly are not sufficient landfills to allow one 

generator source and one solvent per landfill. A municipal landfill in Detroit, for example, 

would receive wipes from numerous automotive plants, from two major airport maintenance 

operations, as well as from numerous other industrial sources, not to mention small 

commercial operations like auto body shops. The assumption of one landfill per source 

therefore is far from reality and results in extremely low stated risk estimates.

These deficiencies could result in risks being understated by several orders of magnitude. For 

example, assuming a landfill serving just 30 wipe generators in a major metropolitan area 

like Detroit, the risks would be greater by at least a factor of 30.

Response: The revised landfill loadings calculations include the number of generators using a 

single landfill. The number of generators using a single landfill ranges from 2 to 67 and is 

based on a state-by-state evaluation of the estimated number of generators, the number of 

landfills, and the degree to which the state uses disposal methods other than landfilling (i.e., 

energy recovery/ combustion) for municipal solid waste. Refer to Section 2.3.6 of the 

Landfill Loadings Report.

• Comment (0288-ETC): Assumptions Regarding Percentage of Wipes With F-Solvents are not 

Appropriate. The approach used in the Risk Assessment appears to be to model a certain 

amount of solvent contaminant with no reduction of the overall results based on assumptions 

regarding the percentage of F-solvents likely to be used in industry or present on the wipe. 

Yet Document-0003 at page 100 states that weighting factors of 35% were applied for Fsolvent constituents and 10% for characteristic solvents. This is based on an assumed 

probability that a given wipe user would only apply an F- listed solvent 35% of the time and 

a characteristic solvent 10% of the time. Such an arbitrary assumption is not appropriate, and 

Document-0003 admits that there are no statistics or facts to support these percentages. EPA 

must not allow use of such weighting factors in the risk assessment, because if solvent wipes 

are exempted from RCRA, there will be no incentive to avoid the use of F-listed or 

characteristic solvents. In fact the usage of such solvents can be expected to increase if wipes 

are exempted from RCRA control, a result that runs counter to pollution prevention. 

Therefore, these arbitrary weighting factors must be eliminated from the risk assessment.

Having assigned this initial weighting factor, then Docket Document-0003 at page 101 states 

that another weighting factor of 50% was applied, because of probability that the actual 

constituent may only be on the wipe half the time. The text says that “these numbers were 

arbitrarily selected.” There is no rationale basis to apply yet another weighting factor that 

only serves to bias the risk estimates to lower values. This 50% assumption must also be 

eliminated from the risk assessment, as it is only an arbitrary guess with no supporting 

information to justify it.
8

The attached AMEC report also challenges these issues in Section 1 and Table 2. These 

assumptions cannot be used as part of the risk assessment.

Response: The Landfill Loading Report no longer includes a separate factor (such as 35 

percent) for estimating the percentage of wipes containing F-listed solvents. Instead, the 

number of facilities assumed to generate F-listed solvent-contaminated disposable wipes was 

estimated from the Economics Background Document (Estimate of National Economic 

Impact of Conditional Exclusion of Solvent Industrial Wipes from RCRA Hazardous Waste 

Regulation (RCRA-2003-0004-0004), updated to 2002 data).

The factor of 50% cited by the commenter (i.e., the probability that the constituent may only 

be on the wipe half the time) was replaced with better supported estimates regarding the 

frequency that particular solvents are used. See Section 2.3.3 of the Landfill Loadings 

Report. For example, 16 percent to 26 percent of wipes used at all facilities generating Flisted solvent-contaminated disposable wipes were assumed to contain acetone. Data sources 

that went into developing this range included data from Kimberly-Clark, the 2003 Biennial 

Report, 2004 Toxic Use Reduction data from Massachusetts, 2004 Toxics Release Inventory 

data, and data collected in support of EPA (1994) Alternative Control Techniques Document 

- Industrial Cleaning Solvents (EPA-453/R-94-015).

The Landfill Loading Report also included a term to account for the potential increased use 

of disposables in the future, if a regulatory exclusion is implemented. Using an earlier 

economic analysis prepared by EPA, the Landfill Loading Report assumed that the

disposable use may increase from 8.1% of the universe of wipes to 17% (see section 2.3.4 of 

the Landfill Loading Report). Furthermore, existing hazardous waste regulations would 

continue to provide pollution prevention incentives toward decreasing the use of F-listed 

solvents, because the use of F-listed solvents would continue to result in the generation of 

listed hazardous waste such as spent solvents. In addition, many F-listed constituents are 

hazardous air pollutants (HAPs). Various NESHAP regulations (e.g., such as those identified 

in Appendix C of the Landfill Loadings Report) provide incentives for a facility to decrease 

its use of HAP-containing solvents.

• Comment (0289-AMEC): Estimated Number of Wipes Used by Industry. The calculated [sic]

used to estimate the loading of solvent waste in landfills assumes that 1,009 million 

disposable wipes are used annually. This value appears to conflict with information presented 

in Table 4 (which identifies the number of entities of various types to which the proposed 

rule may apply, that is, the number of generators) and Table 5 (which identifies the average 

number of wipes used by various types of generators). For example, up to 42,000 printing 

businesses, each of which may use 800 wipes per week, may be affected by the rule, 

resulting in annual use of 6,720,000 wipes daily. The auto repair industry, with up to 35,900 

facilities, uses 100 wipes per day, resulting in 3,590,000 wipes daily. Assuming that 100 of 

the up to 130 military bases are high end users of wipes, using 500 wipes per day (the TSD 

describes high end military base use of wipes as “hundreds per day’), results in an estimated 

1,500,000 wipes per day. The electronics and computer manufacturing industry, with up to

1,500 affected facilities, uses “several thousand” wipes per day at semiconductor facilities 

and nearly 100 wipes per day at printed wire board facilities. Using the geometric mean of 
9

5000 wipes per day and 100 wipes per day results in an average usage of about 700 wipes per 

day, or 1,060,660 wipes per day across this industry. These facilities account for four of the 

fifteen industries potentially affected by the proposed rule, and only 79,500 of 164,000 

facilities (the estimated upper end of the range of affected facilities). The annual sum of the 

industrial wipes used by only the four industries described here is 12,870,660 wipes daily, 

which is equivalent to 3,217,665,000 wipes used annually assuming that generators operate 

only five days per week. Many of the facilities potentially affected by the proposed rule 

operate six or seven days per week, which could result in up to 4,504,731,000 wipes used 

annually. This value exceeds the number of wipes assumed in the TSD by 3.2-fold to 4.5-

fold. Therefore, the number of wipes assumed in the risk assessment may be a substantial 

underestimate of potential loads to landfills and, ultimately, estimated potential risks.

Response: The landfill loadings calculations were modified to use available data regarding 

the number of wipes used per facility multiplied by available data regarding the number of 

facilities. In this manner, the starting point is not the assumption that 1,009 million 

disposable wipes are used annually but instead the starting point is the type of usage data 

cited by the commenter. Variation in the numbers of wipes used per facility (as cited by the 

commenter) is addressed in the revised analysis through two principal methods: (1) explicitly 

differentiating between different industries such as electronics, auto repair, etc., as data are 

available to estimate the numbers of wipes generated and the numbers of facilities; and (2) 

using a probabilistic analysis to address variation in the number of wipes used per facility 

within a given industry.

The numbers of facilities cited by the commenter (e.g., 35,900 auto repair facilities) is greater 

than the numbers used in the landfill loadings calculations. One possible reason for this is 

that the landfill loadings calculations only include facilities which generate disposable wipes.

The numbers cited by the commenter include facilities which handle either disposable and 

reusable wipes (see page 14 of the Economic Analysis, Document No. RCRA-2003-0004-

0004).

• Comment (0289-AMEC): Fraction of Facilities Using F-Listed Solvents. The analysis 

estimates that only 35% of all potentially affected facilities use solvents containing the 

constituents that are the subject of the present analysis. The selection of 35% derives from an 

estimate that 25% of facilities use F-listed solvents and 10% of facilities use 

characteristically toxic solvents. This information is reported to have been derived from 

information in a memorandum from the Screen-printing and Graphic Imaging Association 

International (SGIA), which, according to the TSD, reported using four different F-listed 

solvents with frequencies ranging from 18% to 27%. Using this information, the TSD 

assumes that 25% of facilities use F-listed solvents. However, this simplistic assumption does 

not account for the likelihood that certain facilities may use multiple solvents or mixtures 

containing more than one listed solvent. Moreover, the TSD neglects to mention that the 

SGIA memorandum actually lists five of the most commonly used solvents in this industry 

(the fifth is not a listed solvent), and the percent usage for the five solvents combined

exceeds 100%. This clearly indicates that some facilities use more than one solvent and that 

the percentages reported in the memorandum from SGIA should not be viewed as mutually
10

exclusive. The actual percent of facilities using F-listed solvents is potentially much higher 

than 25%.

(Comment continued) The TSD’s assumption that only 10% of the solvents used by affected 

industries is characteristically toxic is similarly not supported by available data. The TSD 

states that “information from the printing industry” indicates that 10% of the solvents used in 

this industry are non-hazardous, 10% are listed solvents, and 80% are characteristic waste.

Although not specifically cited in the TSD, this information derives from a letter from

Maratek Environmental to Jim O’Leary at EPA. Although the 80% characteristic is not 

further characterized as ignitable or toxic, the TSD makes the assumption that only 10% of 

the solvents in the “characteristic” category is characteristically toxic (and is evaluated in the 

risk analysis) and the remaining 70% of the solvents used are ignitable (and are not evaluated 

in the risk analysis). The assumption that only 10% of characteristic solvents used by this 

industry are characteristically toxic and that a full 70% of the solvents used by the industry 

need not be evaluated in the risk analysis may underestimate the fraction of the industries 

using disposable wipes that may ultimately pose a potential risk to nearby receptors is 

disposed in a municipal landfill. Just because a solvent is designated as a characteristic waste 

due to ignitability does not mean that is not also toxic. The TSD should more vigorously 

analyze the 70% of solvents reported to be used by this industry to ascertain whether this

category contains solvents that may pose a potential risk. Moreover, the assumption that 

“10% of the solvents used by the industry are characteristically toxic” is equivalent to “10% 

of facilities use characteristically toxic solvent” is inappropriate. As described above, it is 

perfectly plausible that a given facility uses multiple solvents or mixtures of solvents, some 

of which may be listed or characteristic and some of which are not. The variable of interest is 

the fraction of facilities using a listed solvent, which is not the same as the fraction of 

solvents among all solvents used by the industry. It may be the case that most or all facilities

use at least one listed solvent, as well as other solvents.

(Comment continued) The fraction of facilities using listed solvents bears directly upon the 

assumed solvent loadings to landfills and, ultimately, upon the estimated risk to receptors 

near municipal landfills. The TSD’s assumption that only 35% of facilities use solvents

containing constituents to which the proposed rule applies is highly uncertain and may 

substantially underestimate the number of facilities using such solvents. EPA should more

thoroughly investigate this variable by collecting solvent use data from various industries to 

derive a value that is valid and supported by industry data. Given the present lack of

information, as well as information described above from SGIA indicating that 90% of the 

solvents used by the printing industry are hazardous, it would be prudent to assume 100% of 

facilities in the affected industries use listed solvents.

Response: The Landfill Loadings Report no longer includes a separate factor (such as 35 

percent) for estimating the percentage of wipes containing F-listed solvents. Instead, the 

number of facilities assumed to generate F-listed solvent-contaminated disposable wipes was 

estimated from the Economics Background Document (Estimate of National Economic 

Impact of Conditional Exclusion of Solvent Industrial Wipes from RCRA Hazardous Waste 

Regulation (RCRA-2003-0004-0004), updated to 2002 data).
11

• Comment (0289-AMEC): Percentage of Wipes That Could Contain a Given Solvent. EPA

cites data from an addendum to the 1997 SAIC document “Use and Management Practices of 

Solvent Contaminated Industrial Shop Towels” as the basis of the assumption that the 

likelihood of industrial wipes containing certain listed solvents is 50%. While the 1997 

document is available in the docket, the addendum containing these data was not located in 

the docket. This information is crucial for readers to be able to verify the estimated loadings 

reported in the TSD and should specifically be included in the TSD. The TSD arbitrarily 

assigns a probability of a given constituent being present on a wipe as 50% for those 

constituents documented as having been used in a study performed on solvents used in the 

printing, furniture, and auto body repair industries. A 50% probability of being present was 

arbitrarily assigned to other constituents considered by EPA to be “less toxic,” and a 10% 

probability of being present was arbitrarily assigned to the remaining constituents. Although 

the TSD posits that facilities would use the less toxic solvents more frequently than higher 

toxicity solvents; no evidence for this theory is presented. In fact, according to the docket and

information in the TSD, EPA has conducted site visits of facilities that would be affected by 

this proposed rule, and has not used these opportunities to collect information regarding the 

theory that facilities preferentially use less toxic solvents solely because of their lower 

toxicity. Moreover, if the proposed rule is implemented, and the proposed solvents are 

deregulated and no longer considered “hazardous,” facilities may use higher toxicity solvents 

more frequently. Assigning the lowest probability of use to constituents of higher toxicity 

does not result in an overall high-end estimate of potential exposure.

Response: The factor of 50% cited by the commenter (i.e., the probability that the constituent 

may only be on the wipe half the time) was replaced with better supported estimates 

regarding the frequency that particular solvents are used. See Section 2.3.3 of the Landfill 

Loadings Report. For example, 16 percent to 26 percent of wipes used at all facilities 

generating F-listed solvent-contaminated disposable wipes were assumed to contain acetone.

Several data sources that went into developing this range include data from Kimberly-Clark, 

the 2003 Biennial Report, 2004 Toxic Use Reduction data from Massachusetts, 2004 Toxics 

Release Inventory data, and data collected in support of EPA (1994) Alternative Control 

Techniques Document - Industrial Cleaning Solvents (EPA-453/R-94-015). These sources 

are documented and cited for each constituent.

• Comment (0289-AMEC): Amount of Solvent on Each Wipe. The TSD states that the amount 

of solvent assumed to be present on wipes was based upon data collected during EPA site 

visits to relevant facilities. However, these data are not reported in the TSD, making it

impossible for the reader to verify the estimated loadings to landfills. Nevertheless, the TSD 

indicates that the assumed solvent loadings onto wipes were values from the “middle of the

distribution” (equal to wipe mass for wipes used by printing industries and equal to one- half 

wipe mass for wipes used by other industries). The TSD also states that some of the facilities

used wipes on which solvent equal to two to four times the wipe mass was used. The use of 

middle or median values underestimates high-end exposures and does not achieve the desired 

“high-end exposures” discussed in EPA (1992). The TSD should fully describe the range of 

findings regarding solvent loads on wipes and should select a high-end parameter value for

this variable such that the overall exposure is consistent with EPA’s desired high-end 

exposure. Table 2 shows the central tendency values used in the TSD to estimate solvent 
12

loading to landfills, high-end values for those parameters, and the factor by which the 

potential risks would increase if high-end values were used.

Response: The revised Landfill Loadings Report includes improvements in referencing or 

describing the assumptions used for the amount of solvent on each wipe. Refer to Section 

2.3.2 and Appendices A to E of the report. To account for the variability in this parameter 

(e.g., facilities using different quantities of solvent), as well as other parameters, a 

probabilistic analysis is used. Calculation inputs account for the full range of data regarding 

the quantity of solvent on each wipe (i.e., a single value for solvent quantity representing the 

“middle of the distribution” is no longer used).

• Comment (0289-AMEC): Quantity of Solvent Going to Landfills. The documents in the 

docket to this proposed rule provide ample evidence that free liquids will be disposed in 

landfills and will pose a substantial threat to landfill liners. For example, in the TSD (Docket 

Number 0003) the quantity of solvent can be as high as 7:1 and typically can be on the order 

of 3:1. These same ratios are given in Docket Documents 0011and 0040. A wipe typically 

weights 10 grams. This means that a wipe can contain 30 to 70 grams of solvent after use.

Removal efficiencies cited on page 65 of Docket Document 0003 vary greatly, and for 

techniques other than centrifuging, range from 3.5% to 24%. Assuming the high end of this 

efficiency performance, the net result is a range of 22 to 53 grams of solvent remaining on a 

wipe following application of solvent extraction techniques condoned by this proposed rule.

Other sources in the Docket also indicate comparable amounts of solvent per wipe following 

“extraction.” For example, page 4 of Document 0040 indicates these same amounts of 

solvent. Another document (RCRA-2003-0004-0127) indicates that after hand wringing a 

range of 40.56 grams to 75.79 grams remained on wipes, which were hand wrung to the “one 

drop criteria.” This document was a study in which 34 replicates were done, meaning that it 

is statistically reliable. EPA is considering allowing hand wringing as an acceptable 

extraction technique to satisfy the “no free liquid” criteria. Docket Document Number 0012 

page 3-33 which assesses shop towel usage in the automotive and printing industries cites 

typical solvent mass remaining on a wipe as 0.031 lbs to 0.065 lbs, or 14.1 to 29.5 grams.

This was purported to be a study that evaluated 599,000 towels.

Another study was performed by a manufacturer of high efficiency solvent extraction 

technology; the Fierro Process (see Docket Document 0122). In this study, wipes were 

collected from 5 different industry types. These wipes were judged by the generator to satisfy 

the “no free liquids” criteria, and apparently had no free liquids in the bottom of containers 

following transportation. Yet after application of the Fierro Process an additional 5.3 to 9.8 

gallons of solvent were removed from wipes per 55 gallon drum of contaminated wipes. This 

study shows that substantial amount of solvent remains in wipes that contain no free liquids.

These solvents can be released under compressive forces in a MSW landfill, or from 

laundered wipes to wastewater discharges, despite meeting EPA’s subjective and weak “no 

free liquids” criteria.

Response: The revised Landfill Loadings Report includes improvements in referencing or 

describing the assumptions used for the amount of solvent on each wipe. Refer to Section 
13

2.3.2 and Appendices A to E of the report. To account for the variability in this parameter 

(e.g., facilities using different quantities of solvent), as well as other parameters, a 

probabilistic analysis is used. Calculation inputs account for the full range of data regarding 

the quantity of solvent on each wipe (i.e., a single value for solvent quantity representing the 

“middle of the distribution” is no longer used).

The Landfill Loadings Report does not address the fate of the constituents once in the 

landfill, including any threats to landfill liners. These issues are addressed in responses to 

other aspects of the risk assessment in “Response to Comments on the Solvent Contaminated 

Wipes 2003 Risk Screening Risk Analysis,” in the docket for the final rule.

• Comment (0289-AMEC): The TSD includes several parameter assumptions, methodological 

approaches, and assertions that are incompletely referenced, supported, or described:

o Estimated Solvent Loading to Landfill. The reported range of estimated constituent 

loadings to landfills (1.13 kg/d to 10.4 kg/d) cannot be verified because the TSD does 

not report the fraction of wipes containing given solvents or the fraction of a given 

constituents in a solvent. The TSD must be revised to include all data necessary for 

the reader to verify calculations.

o Concentration of Constituents in Solvents. EPA cites data from an addendum to the 

1997 SAIC document “Use and Management Practices of Solvent Contaminated 

Industrial Shop Towels” as the basis of the assumed concentrations of constituents on 

industrial wipes. While the 1997 document is available in the docket, the addendum 

containing these data was not located in the docket. This information is crucial for 

readers to be able to verify the estimated loadings reported in the TSD and should

specifically be included in the TSD.

Response: The revised Landfill Loadings Report includes improvements in referencing or 

describing the assumptions used for the above parameters. The fraction of wipes containing 

solvent, the concentration of constituent in solvent, and other parameters are described in 

Section 2.3 of the report with supporting data in Appendices A to E.

• Comment (0323-Cement Kiln Recycling Coalition): USEPA states a belief that the screening 

assumptions underlying the proposed rule are conservative. However, they are not 

conservative when taking into account EPA's lack of an uncertainty analysis. Without the use 

of an uncertainty analysis, it is likely that the risks imposed by this proposed regulation are 

not fully understood. EPA has estimated that the uncertainty exceeds an order of magnitude.

When taken into account with the carcinogenic risk being allowed to pass at (1 in 100,000), 

this leads to the incorrect conclusion that this rule, as proposed, poses no risk to human 

health. ... EPA should not exempt waste under this rule until a valid and full risk assessment, 

complete with uncertainty analysis, has been completed that is at least equivalent in quality 

and stringency to that required for waste de-listing petitions.

Response: The Landfill Loadings Report includes an analysis of uncertainty and sensitivity.

Uncertainty in the input parameters is evaluated through the use of a probabilistic analysis.
14

This results in a probability distribution of the loading of each constituent. Sensitivity of 

these input parameters is also evaluated, as discussed in Sections 2.4.2 and 3.4.2 of the 

report. Sensitivity is useful for determining the effect that changes in input parameters have 

upon the results. EPA completed a revised risk assessment, which was presented in the 2009 

NODA, that addresses other aspects of the comments.

4. Comments Primarily Addressing Assumptions for Reusable Wipes 

• Comment (0271-CTDEP): On page 65609 of the proposed rule preamble (column 3, 

paragraph 3), EPA notes that its data used to analyze the potential risks from disposal of 

sludge from wastewater treatment at laundries consisted of “a very limited number of 

wastewater concentrations collected from industrial laundries by the Office of Water as part 

of their effluent guidelines development process.” CTDEP is aware that these kinds of results 

can vary widely—both in the constituents detected and the concentrations of such 

constituents from one industrial laundry to the next, and from one sampling event to the next 

at the same laundry. This can be due to a number of factors, including variations in the 

customer mix of wipes coming in to the laundry on any given day, and the specific types of 

items that the laundry processes (some industrial laundries may specialize in wipes only, 

whereas others may launder numerous additional items including uniforms, “walk-off” mats, 

and other items). CTDEP therefore suggests that EPA ensures that sufficient data is used in 

the risk analysis to account for such variability, to ensure that the land disposal of the laundry 

sludge is appropriate in all circumstances.

Response: Additional data were used to characterize wastewater generated from the washing 

of shop towels, in addition to washwater for printer towels (See Section 3.3 of the Landfill 

Loadings Report). These data also were collected by the Office of Water as part of their 

effluent guidelines development process. Nevertheless, uncertainty remains because data are 

not available to more adequately characterize either the wastewater generated from the 

washing of wipes or the sludge generated from the treatment of wastewater. The scope of the 

analysis does not include constituents which may be present in other textiles washed by the 

industrial laundry (e.g., uniforms as mentioned by the commenter).

• Comment (0348 (Appendix M) - UTSA): EPA’s Input to the Screening Model, Which 

Assumes 100% Undiluted Wastewater From Printer Towel Processing, Is Incorrect. EPA’s 

decision to use analytical data on printer towel washwater analysis (as described above) 

establishes inputs to the risk model that are too conservative and totally unrealistic. There are 

no industrial laundries that process only printer towels (i.e., 100% of their production is 

printer towels), which then generate wastewater sludge destined for municipal landfills. A 

review of the LaundryESP® database indicates that for the year 2002 only eight facilities 

processed greater than 10% printer towels (as a percent of total production) (see attached 

chart). Of these facilities, the top five, and six of the top eight, all manage their operations in 

such a way as to generate a wastewater treatment sludge that can be sent to a fuel-blending 

contractor (properly manifested as a hazardous waste). That is, the sludge from six of the 

eight facilities with printer towel processing at more than 10% of their production does not 

go to a landfill of any kind. The highest printer towel processing percentage for a 

LaundryESP® facility that sends its wastewater sludge to a landfill is only 12.5%. EPA 
15

presented no empirical data on the maximum levels of towels processed by a laundry. It 

could only make an assumption during its risk assessment. The Agency’s assumption that an 

industrial laundry would have printer towels as 100% of its production is incorrect. The 

LaundryESP® data proves that EPA’s input to its risk assessment model is unrealistic. A 

more accurate input to the risk model would use washwater or wastewater data that are more 

representative of an average industrial laundry’s production mix or for a worse case scenario 

representative of a laundry with a heavy soil production mix.

Response: The commenter is not correct. The analysis does not use an assumption that 

industrial laundries process only printer towels (or only shop towels). As the commenter 

notes, the Landfill Loadings Report uses data from EPA’s Industrial Laundry effluent 

characterization study (EPA, 2000)6; this washwater is representative of the washing of shop 

towels (or printer towels) when washed alone. The landfill loadings calculations only account

for the quantity of shop towels and printer towels processed, and not the entire throughput of 

the laundry (e.g., other materials such as mats and uniforms). The landfill loadings

calculations does not use any assumption regarding the percentage of shop or printer towels 

processed. By only accounting for the quantity of wipes processed, and the estimated 

quantity of chemical in the washwater resulting from the wipes, the analysis is intended to 

estimate only the quantity of chemical in the resulting sludge which originates from the shop 

and printer towels.

• Comment (0348 (Appendix M) - UTSA): EPA’s Data Input to the Screening Model Uses 

Inappropriate Worse Case Pollutant Values. As input to its risk screening model, EPA 

decided to use “[the highest detected concentration from the three samples” it had available. 

Technical Background Document at 129. The Agency indicated that it “does not consider this 

a high-end parameter. EPA has noted the extreme variability of solvent use and therefore is 

not confident that its three data points for characterizing laundry washwater are 

representative. To account for this uncertainty, EPA selected the maximum concentration.” 

Id. 

EPA’s decision to use maximum wastewater analysis values as initial inputs to their risk 

screening model is too conservative. EPA tries to rationalize its decision by noting that 

solvent use on towels can be extremely variable. Solvent levels on individual towels can be 

variable, but EPA has failed to consider properly what each of their printer towel wastewater 

data points actually represent. EPA makes the mistake of classifying the three printer 

wastewater data points as representing three individual printer towels. In reality, the data 

points represent three wash loads of printer towels.7 Each wash load contains approximately

1,200 pounds of soiled printer towels. On average, there are 16 clean towels per pound and 

assuming that each towel contains 100% soil by weight when dirty (i.e., eight dirty towels 

per pound), each washwater sample actually represents a batch of approximately 9,600 soiled 

reusable shop towels. A typical printer towel account might rent 1,000 towels per week. A 

 6 EPA. Technical Development Document for the Final Action Regarding Pretreatment Standards for the Industrial 

Laundries Point Source Category. EPA 821-R-00-006. March 2000. 7 EPA’s Office of Water, Engineering and Analysis Division assumed these data to be representative enough that 

they were used as part of the basis to propose the ELG.
16

batch of 9,600 towels can easily represent 10 or more different printer facilities. So in fact, 

each of the three printer towel washwater data points should be consider representative. EPA 

incorrectly assumes that the data points are not representative and, instead, uses maximum 

values as inputs to the risk model. This is incorrect. EPA should use an average value.

Response: The landfill loadings calculations were revised so that maximum Office of Water 

concentrations were not exclusively used. For each constituent, the average value was used 

as input to the deterministic analysis. A range of values (e.g., minimum, maximum, average) 

were used in the probabilistic analysis.

• Comment (0348 (Appendix M) - UTSA): EPA Assumes an Overly Conservative Risk Model 

Input Value of 2.2 mg/l For 19 Solvents. In its risk screening, EPA looked to the laundry 

industry’s withdrawn ELG for data. In some cases, the Agency found data for the pollutants 

of concern (i.e., F-listed solvents). Eleven of these solvents had data available in the ELG 

database. There were no data available for the other 19 solvents. EPA explains: “The 

remaining 19 solvents were assumed to have a wastewater concentration equal to 2.2 mg/l. 

This is the wastewater concentration of methyl ethyl ketone (MEK), a frequently-used 

solvent by printers. Therefore, solvents used less frequently than MEK are assumed to have 

wastewater concentrations no higher than MEK.” Technical Background Document at 131.

UTSA and TRSA believe that the Agency was again too conservative when it assumed a 2.2 

mg/l input value to the risk model for these 19 solvents. In at least four cases (pyridine, 

nitrobenzene, carbon disulfide, and 1,2-Dichlorobenzene), EPA assumed input values when 

the ELG database indicated that the pollutants were not found in any wastewater samples. 

See EPA Office of Water, Technical Development Document for the Final Action Regarding 

Pretreatment Standards for the Industrial Laundries Point Source Category, Table 5-6 (March 

2000). These four values should be modified to mirror EPA's ELG data (i.e., the values 

should be input as zero or half the detection limit).

As for the other 15 solvents with no ELG data points, EPA's assumption of a concentration 

value equivalent to MEK does not make sense. These 15 F-listed solvents are not commonly 

used, if at all, by printers. Therefore EPA should not use a concentration value representative 

of a commonly used solvent (MEK). It is obvious that for these 15 solvents, the assumed 

value of 2.2 mg/l is too high. A lesser value, which accounts for the infrequent use of these 

F-listed solvents, should be used as a more realistic, yet still conservative, input value to the 

screening model.

Response: The Landfill Loadings Report revised the assumptions regarding the concentration 

of constituents which were either not detected or not analyzed by the Office of Water. These 

assumptions are presented in Section 3.3.3 of the Landfill Loadings Report. For eight 

constituents, a value equal to a typical detection limit (i.e., for cresols) was used. This 

detection limit value was selected as an approximation of washwater levels, in lieu of actual 

data. This average value is 0.305 mg/L for shop towels and 0.433 mg/L for printer towels and 

was used as input to the deterministic analysis. For the probabilistic analysis, the range of 

data corresponding to minimum, maximum, and average detection limit values were used.
17

These values were primarily selected as a means to assess the constituents in a conservative 

manner.

An alternative estimate for methanol was used based on Toxics Release Inventory data; this 

methodology is explained in Section 3.3.3. This alternative method was not used for other 

constituents due to a lack of data.

For ten constituents, a concentration of zero is assumed (i.e., the constituent is not evaluated).

The basis for not evaluating ten constituents is presented in Section 1.2 of the Landfill 

Loadings report; these constituents are not expected to be used as solvents and therefore are 

omitted from both the disposable wipes and reusable wipes analyses.

• Comment (0288-ETC): The sludge input parameter was set based on just three data points for 

three wastewater samples, and theoretical assumptions regarding how much of the 

contaminants in the wastewater would partition to the sludge. Although EPA uses the 

maximum wastewater concentration of the three samples in this evaluation, it still is based on 

only three samples. EPA states on page 129 of Document-0003 that “EPA has noted the 

extreme variability of solvent use and therefore is not confident that its three data points for 

characterizing laundry washwater are representative.” Yet these three non representative 

samples are carried thorough the risk assessment anyway, and are then used to attempt to 

justify a nationwide exemption for solvent contaminated wipes managed in laundering 

facilities. Furthermore, EPA limits the risk analysis to only 11 of the 30 solvent constituents, 

since these were the only constituents that happened to be detected in these 3 nonrepresentative samples.

Response: The Landfill Loadings Report continues to use the data from the Office of Water 

sampling program. Ideally, landfill loadings would be based on data regarding the total levels 

of contaminants in the laundry sludge itself. Because such data are not available, the landfill 

loadings are calculated using a series of assumptions which include data regarding the levels 

of contaminants in washwater generated from the washing of shop towels and from the 

washing of printer towels. As identified in comments by UTSA (Comment No. 0348), 

“EPA’s Office of Water, Engineering and Analysis Division assumed these data to be 

representative enough that they were used as part of the basis to propose the ELG [effluent 

limitation guidelines].” While imperfect, no other data were identified to use as a better basis 

for estimating the levels of contaminants in washwater.

• Comment (0288-ETC): As stated above, the three water samples only had data for 11 

constituents. For the remaining 19 constituents EPA simply assigns a concentration of 2.2 

mg/liter (page 131 of Document-0003), which was the wastewater concentration of MEK. 

Their justification for doing this is that MEK is a frequent solvent used in wipes, and the 

other 19 solvents are used less frequently. This assumption is totally biased, is not 

substantiated by fact, and has no bearing on the chemical and physical factors associated with 

how much solvent will tend to be present in a wastewater. Furthermore Table 21 has other 

solvents that are also commonly used on wipes that could have just as easily been selected, if 

the criteria were “common usage”. What about acetone with a starting concentration of 96.6 

mg/liter, or toluene with a starting concentration of 33.2 mg/liter, or xylene with a starting 
18

concentration of 102.7 mg/liter? These are also all common solvents used in wipes in various 

industries. The answer is these would have resulted in 16 to 47 times higher impacts than 

applying the MEK concentration; it appears that EPA wanted to pick a low number for the 

other 19 constituents to bias the results low.

Response: In revising the landfill loadings calculations, alternative sources of data were 

investigated in order to reduce reliance on using an assumption such as assigning the 

chemical concentration of methyl ethyl ketone to other, unrelated solvents. This process is 

described in Section 3.3.3 of the Landfill Loadings Report and is summarized as follows:

o Data for eleven constituents were used directly from the Office of Water sampling 

program.

o Two constituents were not detected in the Office of Water sampling program; a 

concentration equal to the detection limit value of another chemical (i.e., cresols) was 

used for these constituents.

o Data for one constituent (methanol) was estimated using Toxics Release Inventory 

(TRI) data.

o Ten constituents were assumed to be not present in disposables or reusable wipes for 

the reasons identified in Section 1.2 of the Landfill Loadings report.

o The remaining six constituents (benzene, n-butanol, cyclohexanone, ethyl acetate, 2-

ethoxyethanol, isobutyl alcohol) had no data and concentrations equal to the cresols

detection limit values were used for these constituents.

By using the data sources identified above, there still exists a small number of constituents 

(six) for which a concentration is assigned rather than cited or calculated. It is difficult to 

‘forecast’ what the levels of these constituents would be in washwater in the absence of other 

data; however, using values comparable to those for methyl ethyl ketone, acetone, toluene, or 

xylene as suggested by the commenter would be expected to overestimate the concentrations 

of these six constituents. For these constituents, a level approximating a detection limit value 

was assumed to be a better approximation than an assumption of using a level for methyl 

ethyl ketone (or other constituents suggested by the commenter). This value approximating 

the detection limit was selected because (1) no other data are available; (2) the detection limit 

is intended to represent a conservative but reasonable approximation of what levels could be 

present; and (3) based on usage data in Section 2.3.5 of the Landfill Loadings report, the 

constituents are not widely present in solvents and therefore the concentrations in washwater 

would be expected to be less than concentrations of high-use solvents identified in Section 

2.3.5, such as methyl ethyl ketone and acetone.

• Comment (0288-ETC): EPA then selects a partitioning model to calculate how much of the 

contaminant in the wastewater will partition to the sludge (page 130 of Document-0003). In 

doing this model an oil/water separation unit is assumed over a dissolved air flotation (DAF) 

unit because this “results in less solvent partitioning to the sludge than the DAF unit”. In 

other words, EPA simply selects a unit in a biased manner that will result in more pass 

through of contaminants to the effluent, and less retention on the sludge. This is a totally 

arbitrary and biased assumption, with no supporting backup information provided relative to 

what percentage of launderers use oil/water separators versus DAFs. Furthermore, page 3-36 
19

of Document-0012 states that treatment processes used by launderers also include settling 

basins, equalizers, clarification and media filtration. EPA provides no data on what impact 

these types of units would have with respect to sludge partitioning assumptions in the risk 

assessment.

Response: The revised Landfill Loadings Report uses partitioning results both with and 

without the dissolved air flotation (DAF) unit; these partitioning results are used in 

conjunction with data or estimates regarding the frequency that DAF units are present at 

industrial laundries. This evaluation and the source data is presented in Section 3.3.5 of the 

Landfill Loadings report.

The partitioning results are based on modeling conducted in 2000 for evaluating solvent wipe 

constituents (Document No. RCRA-2003-0004-0045). Two different systems were 

evaluated: (1) pit and screen; or (2) pit, screen, equalization, and DAF unit. As stated by the 

commenter, laundries use treatment processes other than these treatment trains. However, 

modeling or partitioning results for these various treatment processes were not available and 

as a result the Landfill Loading evaluation was simplified into the two scenarios, with and 

without a DAF.

• Comment (0288-ETC): Another bad assumption in the sludge partitioning calculation is that 

4.61 gallons of wastewater is generated per pound of wipes (page 130 of Document-0003) 

when the Office of Water data cited in Document-0012 at pages 3-29 and 3-30 is 2.9 to 3.5 

gallons per pound of wipe. A lower wastewater usage rate results in more partitioning to the 

sludge. The ETC could not find where the 4.61 gallons/pound number came from, but the 

Office of Water data would suggest a more realistic and conservative number of 2.9 

gallons/pound of wipe should have been used.

Response: In the EPA Office of Water’s 2006 Effluent Guidelines Plan8, an industry average

of 2.28 gallons washwater generated per pound of textile is identified, based on 2002 data 

evaluated as part of the Laundry ESP program. These data were used because the Laundry 

ESP data are representative of a large segment of the industry and is more recent than other 

available data.

• Comment (0288-ETC): EPA then assigns another arbitrary adjustment factor of 0.5 to 

account for assumed F-solvent usage rates. There is no basis to support such a factor 

reduction.

Response: The 0.5 factor identified in the Technical Background Document (RCRA-2003-

0004-0003) was intended to account “for lower quantity of solvent on shop wipes” as 

compared to concentrations in printer towel washwater. The revised Landfill Loadings 

Report uses Office of Water data9 for levels in both shop towel washwater and printer towel 

 8 EPA Office of Water’s 2006 Effluent Guidelines Plan. EPA-HQ-OW-2004-0032-0763. August 2005. 9 EPA. Technical Development Document for the Final Action Regarding Pretreatment Standards for the Industrial 

Laundries Point Source Category. EPA 821-R-00-006. March 2000.
20

washwater, as identified in Section 3.3.3 of the report. Therefore, in the revised Landfill 

Loadings Report, washwater data for shop towels are used in place of the 0.5 factor.

5. Additional Public Comments Related to Loading Assumptions Not Addressed in the 

Revised Landfill Loading Report

• Comment: The 2003 assessment, and the revised approach above, does not address cocontaminants. Co-contaminants include contamination from the material that the solvent 

removes from the equipment, such as metals, inks, and colors. Public comments related to 

co-contaminants include:

• 0199-Hearing Transcript-David Case, ETC; 

• 0288 (ETC)

• “Gradient Report” as Appendix B in 0283-INDA/SMART comments; 

• “Gradient Report” rebuttal by 0348-UTSA/TRSA comments.

Response: Co-contaminants are excluded from the loadings evaluation to limit the scope and 

to provide a reasonable boundary to the problem statement. Note that solvent-contaminated 

wipes that exhibit a characteristic (other than ignitability) due to constituents other than one 

of the exempt F-listed solvents (e.g., co-contaminant metals) are not included in the 

exclusion. Also, wipes contaminated with other listed wastes would not be eligible for the 

exclusion. Regarding other possible contaminants, note that the F-code solvent listings are 

based on the toxicity and risk presented by the specific solvents which are included in the 

listing descriptions. The language in the listings illustrates EPA’s concern with the solvent

chemicals in defining the scope of the listings. Other potential constituents in the solvent 

wastes vary widely across industries, such that it would be exceedingly difficult, if not 

impossible, to categorize and evaluate these wastes if we considered all other constituents.

Because of the wide variability in waste constituents that might arise in wastes from use of 

the solvents, EPA focused its evaluation on the solvent chemicals themselves. We believe

that this is the most practical approach to evaluating solvent wipes.

• Comment (0257-George H. Larson): EPA should assess risks from the ‘remaining’ solvent 

which is not part of the 8% to 37% of the solvent which partitions to the landfilled sludge.

Response: The revised landfill loading calculation continues to addresses only the portion of 

solvent present in the landfilled sludge. Emission rates or risks resulting from air or water 

are not assessed. EPA addresses other potential risks in responses to comments on other 

aspects of the risk assessment in Response to Comments on the Solvent Contaminated 

Wipes 2003 Risk Screening Analysis,” in the docket for the final rule.

• Comment (0281-Graphic Arts Coalition): The Agency’s own report on the “Evaluation of the 

Solvent Extraction Efficiency of an Industrial Centrifuge on a Variety of Shop Towels and 

Wipes,” clearly states, “that the solvent that seemed to be most easily extracted was MEK.”

In fact, the report states that MEK’s removal efficiency was 99 percent. Based on the 

removal efficiency of MEK of 99 percent rather than 90 percent, we ask the Agency to 

reevaluate the inclusion of MEK as one of the solvents listed in Table 4.
21

Response: The analysis did not include a ‘what if’ analysis regarding the increase in use of 

solvent extraction technology for disposable wipes. The purpose of the analysis was to 

estimate landfill loading based on current wipes management methods without additional use 

of technologies such as centrifuge. Additionally, the final risk analysis demonstrates that 

wipes contaminated with methyl ethyl ketone do not pose significant risk to human health 

and the environment when disposed in a composite-lined landfill. Therefore, EPA has 

included methyl ethyl ketone in the exclusion.

• Comment (0288-ETC): The Assumption of a Single Solvent, for a Single Wipe, for a Single 

Landfill is not Realistic and Understates the Risk Substantially. The Risk Assessment Report, 

page 6-25, actually states that the manner in which the risk assessment was done “is not the 

way things are in reality.” The risks represent the results for a single facility using wipes with 

a single solvent at a single landfill. As stated in various other background documents, 

multiple solvents are often used on a given wipe. For example, Document-0012 at pages 3-22 

and 3-23 shows multiple solvent constituents typically on a wipe. Document-0003 at page 24 

notes that multiple solvent constituents are used depending upon the demands of the cleaning 

task. Document-0105 provides an MSDS of a commercial solvent mixture called “XCELLO” 

used in the printing industry that contains 5 individual solvent components. Document-0104 

describes a 4 F-listed solvent mixture. Therefore the risk assessment is clearly flawed for 

failing to account for multiple solvent effects.

Response: The assumption regarding the number of generators assumed to use a single 

landfill is part of the landfill loading calculations and this part of ETC’s comment is 

addressed above. The landfill loading calculations do not discuss results from multiple 

solvents in a single landfill. It would be extremely difficult to attempt to assess solvent 

mixtures in any loading analysis. Instead, it was assumed that all the solvent on the wipe was 

a specific solvent, and the resulting risk was assessed. It is difficult to project what the impact 

of this assumption is, given that the potential risks of solvent mixtures would depend on the 

relative toxicities of the individual solvents. Also, mixed solvents may contain solvents that 

are not listed (i.e., are not included in the F-listings). In any case, the landfill loading 

estimates and the risk-based mass loadings are based on relatively conservative assumptions

(e.g., using 90th percentile loading estimates), mitigating any possible effect of multiple 

solvents.

• Comment (0289-AMEC): Quantity of Solvent Going to Landfills. The documents in the 

docket to this proposed rule provide ample evidence that free liquids will be disposed in 

landfills and will pose a substantial threat to landfill liners.

Response: The landfill loadings report does not address the fate of the constituents once in 

the landfill, including any threats to landfill liners. These issues are addressed in responses to

comments on other aspects of the risk assessment in “Response to Comments on the Solvent 

Contaminated Wipes 2003 Risk Screening Analysis,” in the docket for the final rule. Note, 

however, that the final exclusion for solvent-contaminated wipes includes conditions that 

specify the wipes must contain no free liquids prior to being sent for disposal.
22

• Comment (0288-ETC): Given the lack of data on wastewater (3 samples) and sludge (0 

samples) with which to do a risk assessment, EPA should be starting with better 

characterization data. For example, an actual sludge analytical survey could have been done. 

Also, EPA could have started with the same starting point used for wipes as described above 

for disposable wipes sent to MSW landfills. Using 75.8 grams of solvent per wipe and a 

usage rate of 1000 wipes per day, EPA could have then calculated the total solvent loading to 

assume for laundering facilities. Then actual mass balances studies could have been done on 

10 average size laundry facilities and 3 large laundry facilities to obtain reliable partitioning 

data. This should be done on a variety of laundry facilities using all of the possible waste 

water treatment options identified on page 3-36 of Document-0012. Then more reliable 

sludge data would have been available to input to the risk assessment. Note that there is one 

mass balance study in the record (Document-0045) but this study is not a true mass balance 

as it uses entirely theoretical factors, as well as related data assumed from AP-42 calculations 

from other sources.

Response: The Landfill Loadings Report primarily relies on data from previous EPA work or 

on documents already in the docket. EPA did not collect additional sludge characterization 

data or mass balance studies; therefore, such data were not available for use in the landfill 

loading assessment.

The approach suggested by the commenter (e.g., estimating quantities of solvent on 

generated wipes sent to laundries) would continue to rely on a series of assumptions, as does 

the existing approach used in the Landfill Loadings Report. One advantage of the current 

approach (e.g., using washwater characterization data) is that the washwater is ‘closer’ to the 

resulting sludge than generated wipes.