# Response to Comments on the 2009 NODA 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

S AIC

12100 Sunset Hills Road Reston, VA 20190

EPA Contract No.: EP

- W

- 05

- 0601 1. Introduction

In response to EPA’s 200 9 Notice of Data Availability (NODA) regarding the conditional exclusion of wipes ( 74 FR 55163

, October 27, 2009 ), EPA received comments re garding the approach and assumptions used in estimating the quantity of solvent t h at 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 document prepared for the

2009 NODA that contains the principal landfill loading assumptions is “ Landfill Loadings Calculations for Disposed Solvent

- Contaminated Wipes and Laundry Sludge Managed in Municipal Landfills

, ” January 2008 (Docket No. EPA

- HQ

- RCRA

- 2003

- 0004). This is referred to below as the ‘Landfill Loadings Report’ or ‘landfill loadings

calculations’

The public comments identified below present comments related to this p ortion of the

risk assessment. The relevant portions of the comments are presented verbatim; full

comments are in the docket for the final rule. If appropriate, revisions to the landfill loading calculations and/or the report were made to address these public comments. An explanation is included as to how the revised analysis addresses each comme nt. The revised, final Landfill Loadings Report is in the docket for the final rule ( Landfill Loadings Calculations For Solvent

- Contaminated Wipes

, January 2012 ).

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

r isks to receptors. Comments relating to these other p o rt ion s of the risk assessment, such as fate and transport assumptions, are not identified below , but may be found in the

document entitled Response to Comments on the Solvent Contaminated Wipes 2009 Ris k Analysis: Risk

- Based Mass Loading Limits

, which is in the docket for the final rule.

2

. Comments Primarily Addressing Solvents Selected for Inclusion in the Analyses

• Comment (0447

– John Deere ): We agree with the scope EPA is taking, eliminating

ten of the 30 solvents listed in 40CFR 261.31 because they are banned or restricted from use. Deere has defined a list of restricted materials applicable to John Deere

facilities worldwide. Eight of these solvents (Carbon tetrachloride, 1,1,1

- Trichloroethane, Tri chlorofluoromethane, Dichlorodifluoromethane, 1,1,2

- Trichlorotriflur o ethane, Nitrobenzene, 2

- Nitropropane and Pyridine) have been banned by Deere from all products and facilities. Deere agrees that the other two solvents, Carbon disulfide and Ethyl ether, are currently restricted from use in solvent applications.

RESPONSE : The commenter’s information is consistent with that provided in Sections 1.2.1 and 1.2.2 of the Background Document. No change to the background document or calculation is made as a resu lt of this comment

.2 3

. Comments Primarily Addressing Assumptions for Disposable Wipes

• Comment ( 0458

– Graphic Arts Coalition, page 2

- 3 ): On page 21 of the aforementioned report, Section 2.3.6 states: “As identified in Section 2.3.4, approximately 30,000 generators are assumed to generate F001 to F005 solvent contaminated disposable wipes; these generators are assumed to dispose their spent wipes as nonhazardous waste.”

The assumption that all 30,000 generators are disposing of their solvent contaminate d wipers that have been used in conjunction with a F001

- F005 solvent is not accurate as very few facilities in the printing industry use F listed solvents for cleaning. In addition, current state policies do not allow generators to disp ose of shop towels

c ontaminated with a listed waste into a municipal landfill. The inten t of the proposal issued by the Agency in 2003 is to establish those parameters that w ould allow facilities to safely dispose of their solvent contaminated wipers into a municipal

landfill

.

RESPONSE : The derivation of the estimate that there will be 30,000 generators

of F001

- F005 solvent

- contaminated disposable wipes is provided in Section 2.3.4 of the report, as identified by the commenter. The calculation incorporates an

estimate of the percent of generators using F001

- F005 solvents. The commenter’s information that ‘very few’ printing facilities use F001 to F005 solvents is difficult to incorporate into a quantitative estimate. EPA believes that the approach used in the report is appropr iate, absent any data to the contrary.

The commenter correctly notes that the report assumes that all generators will dispose their contaminated wipes as nonhazardous waste (e.g., by municipal solid

waste landfill), whereas under current regulation and st ate policies this assumption is not valid. The report makes the assumption to evaluate the impact if the policies were to change and the wipes were disposed as nonhazardous waste.

No change to the background document or calculation is made as a result of this

comment.

• Comment (0458

– Graphic Arts Coalition, page 3): Further, the Agency does not recognize in its data analysis on landfill loadings that many printing facilities have migrated to the use of cleaning solvents that do not contain constituents th at would render their solvent contaminated wipes a nonhazardous waste since the products used do not contain any listed solvents nor do they exhibit a hazardous waste characteristic. The assumption made in the report is that all facilities are using RCRA

s olvents. This is no longer accurate and is not supported by the data points in the current docket. Even in 1998, printing facilities were migrating to solvent technology

that resulted in the creation of non

- hazardous waste. While the towels contaminated

wi th the nonhazardous solvents would no longer be subject to regulation, the important point is that the total number of facilities that would be disposing of3 disposable towels with RCRA regulated solvents would be less than what is currently

assumed.

RESPO NSE : The commenter is not correct in it s statement that EPA assumed

that all facilities are using RCRA solvents. As i dentified in Section 2.3.4 of the

report, not all facilities are assumed to use RCRA solvents. Further, of the facilities using RCRA solven ts, the report in Section 2.3.3 assumes that a fraction of their wipes contain the RCRA solvents (i.e., they do not exclusively use RCRA solvents, but use a variety of hazardous and nonhazardous solvents). The data used in the report are based, in part, on data from the printing industry provided by the Specialty Graphic Imaging Association (the commenter states that the Graphic Arts Coalition includes the Specialty Graphic Imaging Association ).

No change to the background document or calculation is made a s a result of this

comment.

• Comment (0459

– National Automobile Dealers Association , page 3 ): Again, vehicle maintenance wipes often are contaminated with other haza rdous or nonhazardous

materials.

RESPONSE : Th e commenter confirms part of the approach in cluded in the Background Document, namely that wipes are used in the vehicle maintenance

industries. This industry was included in the report (Section 2.3.1). No change to the background document or calculation is made as a result of this comment.

The por tion of the comment s tating that wipes include a variety of contaminants (which may be different than the 30 solvents in the F001

- F005 listings) is not

addressed in the Landfill Loadings report

. If solvent

- contaminated wipes exhibit a

characteristic due to constituents other than one of the exempt F

- listed solvents (e.g., co

- contaminant metals), the wipes are not eligible for the exclusion

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

exclusion . Regarding other possible co ntaminants, note that the F

- code solvent listings are based on the risk presented by the specific solvents which are included in the listing descriptions

. T he language in the listings illustrates EPA’s concern

with the solvent chemicals in defining the sco pe 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 o f the wide variability in constituents that might arise in wastes from use of the solvents, EPA focused its

evaluation on the solvent chemical s themselves

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

.

• Comment (0464 att achment

– INDA/SMART (Geosyntec) , page 11) : Fitted

Distributions for Parameters with Limited Datasets Result in Highly Over

Conservative Mass Loading Levels and Therefore Overestimate Risk

. For many4 chemical loading parameters, robust datasets were lacking and a small number of empirical measurements were used to represent the populations of interest by fitting the data to a population distribution (parameterization). EPA guidance suggests

caution in fitting distributions to data, especially when selecting the type of model for

the parameterization. 1

, 2 Inputs parameters were assigned to a distribution with little consideration as to the underlying mechanism that may give rise to those distributions (e.g., lognormal or normal distributions). Selecting the inc orrect distribution can have

a large impact in the results, particularly when the results reflect upper bound

estimates. For example, consider the difference between a uniform distribution within a fixed range and a parametric distribution with a finite pr obability of extreme values.

Extreme solvent loading values may even violate the im plicit assumption that solvent

l oading is meeting the requirement of the risk assessment scenario (no free liquids).

For example, the solvent loading rate per wipe for all industries except printing was estimated by EPA to fit a Weibull distribution (Exhibit H

- 7 in the Landfill Loading s Report). Given this distribution we would expect 1% of the wipes to contain 144 grams of solvent (Figure 4). Over 10,000 simulations, multip le loading rate values exceeding 200 grams would be selected. Such unrealistic mass loading levels were included in the analysis. Risks calculated under the assumption of no free liquids were developed under loading conditions that likely overestimated the potential loading rates. 3

[Figure 4. Assumed Loading Rate Per Wipe in the Non

- Printing Industry.]

RESPONSE : The general approach used for selecting and using parameter distributions are included in Section 1.3 of the Background Document. In particular, when deciding the type of distribution for the calculations, a distribution with the highest

- ranking fit was typically selected because

, for most input parameters (such as the amount of solvent on the wipe) , no mechanistic basis exists to assess which

dist ribution assumption is most appropriate

. The commenter states that the parameter distributions were made with little consideration of the underlying reason or

mechanism for the distribution. This is not correct because in most cases no

information was avai lable for these underlying mechanisms; if information was available it would have been considered in selecting the distribution.

The commenter states that an ‘upper bound’ of the amount of solvent per wipe would be reasonable to ensure that the wipe would meet a no free liquids requirement. T he commenter suggests that values in excess of 200 grams per wipe would be

unreasonable.

1 EPA (1999). “Report of the Workshop on Selecting Input Distributions for Probabilistic Assessments.”

630/R

- 98/004.

2 Crystal Ball (Version 7) does not allow fitting data to distributions for less than 15 samples due to the high degree of uncertainty.

3 Conservatism in estimates of loading rates is evidenced by the fact that each chemical in the risk assessment was assumed to be loaded on the same group of wipes. Coll ectively the total solvent on the wipes is above the empirical observations and potentially above the solvent capacity of the wipes.5 In considering this comment, EPA noted that a pplying an ‘upper bound’ is consistent with EPA guidance. 4 The following guidance f rom Appendix B of EPA’s ‘Risk Assessment Guidance for Superfund’ (RAGS) is applicable here:

o Truncation may be considered when using unbounded probability distributions (e.g., normal, lognormal, gamma, Weibull) to characterize variability.

o Identifying appro priate truncation limits that reflect “plausible bounds” for an exposure variable will often require judgment.

o Sensitivity analysis can be used to determine if truncation limits are an important source of parameter uncertainty in risk estimates.

The follo wing change to the background document or calculation is made as a result

of this comment. Setting an upper bound for the amount of solvent on a wipe is one possible approach to try to account for the ‘no free liquid’ requirement

. H owever
, selecting a reas onable value for this upper bound presents some difficulties due to the

limited data

. The initial sensitivity analysis presented in the report (i.e., Section 2.4.2 of the Landfill Loadings Report ) suggests that the amount of solvent on the wipes is

not a p articularly sensitive input parameter, so modifications to this distribution are not expected to impact results. To further investigate the importance of this parameter, a ‘what if’ analysis was conducted for two chemical s by setting the upper

bound as 100 g/wipe . This value was chosen as an upper bound because no

observations were above this value

. The results of this analysis are included in

Section 2.4.3 of the revised report. The landfill loading results were slightly lower when this limitation was pres ent, but the magnitude of the difference was less than 8

percent at the 90 th percentile when compared to the original analysis. Therefore, we find that the slightly more conservative approach used in conducting the analysis is

reasonable.

• Comment (0464 at tachment

– INDA/SMART, page 13

- 14): Chemicals Included in the

Risk Assessment Were Sufficient to Address Risks

. Chemicals included in the risk

assessment were sufficient to address the risks associated with landfill co

- disposal of wipes and laundry sludge. Several solvents were excluded from the analysis based on use data that indicates these are no longer widely used industrial solvents. Use of solvent such as benzene, trichloroethylene, and tetrachloroethylene are being phased out. In general, it is expec ted that organic solvent use will continue to decline as more environmentally friendly solvents are employed. The data selected to evaluate the types of solvent used and the proportion of those solvent in waste stream is generally at least five to ten year s old 5 and may not reflect more recent changes in industry practices and movement to reduced risk solvent use.

RESPONSE : I t is possible that the assumptions regarding the use of chemicals and solvents may not reflect current use patterns due to some of th e reasons cited by the commenter; this limitation was acknowledged in Section 2.4.4 of the Landfill

4 EPA, ‘Risk Assessment Guidance for Superfund. Volume III

- Part A, Process for Conducting

Probabilistic Risk Assessment.’ EPA 540

- R

- 02

- 002 . December 2001.

5 Landfill Loading Report

– Appendix A and B. SAIC, October 2008.6 Loadings Report

. However, the commenter did not present any specific data on this question. Due to a lack of data to quantify how solvent use would change i n the future, the Landfill Loadings Report did not include these effects. With specific regard to benzene, trichloroethylene, and tetrachloroethylene, the Landfill Loadings Report used data from the 2004 Toxics Release Inventory as a basis for assumptions regarding the maximum percentage of sites expected to use these chemicals in solvents for wipes; these maximum percentages were 2.1%, 1.8% and 0.9% for benzene, trichloroethylene, and tetrachloroethylene, respectively. These percentages already reflect a l ow proportion of facilities.

No change to the background document or calculation is made as a result of this

comment.

4 . Comments Primarily Addressing Assumptions for Reusable Wipes

• Comment (0461

– TRSA, page 8): Printer Towels vs. Shop Towels. A portion of the old ELG data included the pounds of shop towels and the pounds of printer towels washed by individual laundries. This data showed that 1,332 laundries managed shop towels and 480 managed printer towels. EPA’s contractor did not identify the percent of facilities that manage both printer and shop towels. Instead, EPA’s contractor assumed in the NODA: (i) that all laundries manage shop towels; (ii) that there is a 36% probability that a laundry that manages shop towels also manages printer towels;

and (iii) that laundries only process shop or printer towels and no other textile products. 6 EPA’s contractor also indicates that trends over the past 10 years were not assessed with respect to how the data regarding the pounds of shop towels vs. printer

towe ls washed by in dividual laundries has changed.

The assumptions here regarding the processing of shop towels and printer towels

contributes to the substantial overestimation of the volume of solvent

- containing laundry sludge going to landfills. Not all lau ndry facilities manage shop towels. ( See Section III below). Similarly, the assumption that 36% of laundry facilities manage shop towels and printer towels is also high. Id . Indeed, TRSA estimates that approximately 19% of industrial laundry facilities pro cess printer towels and shop towels, which represents less than 10% of the laundry industry’s overall business. EPA’s contractor has ignored the significant volume of textile item such as uniforms, floor mats, linens, mop heads and other products that co nt ain little, if any, solvents.

This incorrect assumption skews the overall laundry sludge risk assessment. The two most sensitive parameters in the model are quantities of shop towels washed and quantities of printer towels washed. TRSA agrees that signifi cant uncertainty is created by the sensitivity of these parameters. Indeed, because the pounds of shop towels washed drives the gallons of washwater generated per pound, which in turn affects the mass loading of solvent in laundry sludge through the partit ioning process, an overestimation on the front end (i.e., the quantities of shop towels and printer towels washed) will affect the mass

- loading estimate

– perhaps by orders of

6 The latter assumption is significantly misleading as shop and printer towels generally comprise only a small fraction (less than 10%) on most laundry’s pr oduct mix.7 magnitude. And, as noted herein, shop and printer towels are only a minor fracti on of the product mix at most laundry facilities. This, too, overestimates mass loading

calculations.

RESPONSE : The effluent limit guideline ( ELG ) data were used appropri ately in the Landfill Loadings R eport. The ELG data collection effort was substantial , as noted by the result that data were collected from over 1,000 laundries. The landfill loadings calculations were conducted in such a way as to isolate the effects of shop and printer

towels f r om other textiles such as uniforms

. Note that s ection 3.3.2 of the Landfill Loadings R eport is in error where it state s that the report assumed that all laundries manage shop towels. However, t his is an error in the text, not in the calculation approach. Specifically, Section 3.3.1 of the report identified that of 190 laundries

from the ELG effort , 141 processed shop towels and 71 processed printer towels. F or the purpose of the calculation, the report ignores any laundry that does not manage either shop or printer towels, and ignores loadings from non

- towel textile s such as uniforms which are also managed by laundries. This is done to isolate loadings from sludges attributed to shop and printer towels.

The assumption of 36% probability that a laundry that manages shop towels also manages printer towels is well docu mented in the report (Section 3.3.2) . The percentage simply reflects the number of laundries washing printer towels as a proportion of those washing shop towels (480/ 1,332). The commenter’s proposed

modification of this value to 19% is addressed in more d etail in a later comment.

As a result of this comment, the Landfill Loadings Report is changed by clarifying Section 3.3.2 in regards to laundries managing shop or printer towels as well as other

textiles.

• Comment (0461

– TRSA, page 9 ): Solvent Concentra tion in Washwater. EPA’s contractor estimated the quantity of wastewater generated, deriving an industry average of 2.8 gallons/pound of textile based on 2002 water use data gathered from the Laundry ESP program. Based on sampling data gathered by the Offi ce of Water during the ELG process, EPA’s contractor also estimated concentrations of solvents in laundry washwater after washing both printer and shop to wels.

The estimates of quantity of wastewater generated and the concentration of solvent in

wastewate r are high. The most recent Laundry ESP results indicate that the industry, on average, uses 1.6 gallons/pound of textile. See 2006 Laundry ESP Report attached

hereto as Exhibit “A.” 7 This represents a savings of 26 billion gallons of water from

1997 avera ges (or the water usage of about 700,000 people per year). Most significantly, in performing its calculations, EPA’s contractors used data taken from processes only involving shop towels and printer towels. Shop and printer towels are only a portion of ove rall production of most facilities. The other textile items, uniforms, floor mats, etc., would not be expected to contain any of the regulated

7 These TRSA data are only four years old, as compared to the ELG data that are now more than fourteen years old.8 solvents. By focusing only on the wastewater from shop and printer towel washing, EPA has greatly over

- estimated wastewater solvent concentration.

RESPONSE : The commenter provided a report entitled ‘Laundry Environmental Stewardship Program: Laundry ESP’ which supports its claim that 1.6 gallons of

water are used per pound of textile. In addition , the commenter also provided survey data for the same parameter (addressed in more detail in a later comment). Both the ESP report and the comme nter’s survey data are more recent than the value used in the original Land fill Loadings Report. Therefore, EPA has modified t he fi nal Landfill Loadings report and calculation s by including the survey data , rather than the ESP report, due to its detail

.

As noted in a previous comment, the l andfill l oadings calculations were conducted in such a way as to isolate the effects of shop an d printer towels from other textiles such

as uniforms. For this reason, the analysis uses washwater from shop and printer towel washing. Including additional textiles as suggested by the commenter would have two

effects :

(1) the washwater concentration te rm used in the calculation would decrease because it would be ‘diluted’ with water from other textiles which are not being evaluated for this effort; this effect was noted by the commenter; (2) the total washwater volume used in the calculation would incr ease due to the additional textiles considered; this effect was not noted by the commenter.

While these effects may or may not cancel each other out, they would add a layer of complexity to the calculation. Therefore, EPA maintained the simpler approach o f isolating the washwater volume and the washwater concentration in the landfill loadings calculation s for the wastewater treatment sludge

.

• Comment (0461

– TRSA, page 9): Sludge Partitioning. To estimate a total mass of washwater and solvent, EPA’s contra ctor estimated the pounds of printer towels and shop towels washed, and the quantity of washwater. EPA’s contractor then used a partitioning model to estimate the portion of chemical in the wastewater that will partition to air or sludge, or remain in the water. As EPA’s contractor recognize, this modeling approach was necessary because sludge samples were not collected. See Landfill Loadings Background Document, at 37.

The assumptions for this model include: (i) a reduction in volatility due to surfactan t; and (ii) consideration of both a pit and screen (55% of facilities) and a pit, screen, equalization, and dissolved air flotation (45% of facilities) wastewater management systems. The results are expressed as a fraction of chemical in coming washwater

w hich partitions to sludge.

This partitioning process, at bottom, is hypothetical and depends entirely on the previously estimated volume of solvent

- contaminated washwater. As noted, EPA’s contractor has overestimated both the quantity of incoming washwat er, and the9 quantity of shop and printer towels being processed and the concentrations of solvents in laundry wastewaters. And therefore, overestimated the quantity of each solvent “partitioning” to the sludge. The result, ultimately, is a compounding of t he errors in the estimations of solvent contained in laundry sludge, and an inaccurate risk

as sessment.

RESPONSE : Specific elements from this comment are addressed in detail in other

comments:

o O verestimat ion of the quantity of incoming washwater : address ed above (i.e., EPA modified the amount of water used per pound of textile based on the commenter’s survey data )

.

o Overestimati on of the quantity of shop and printer towels being processed : addressed below regarding survey data provided by the commenter

,

o Ov erestimating the concentrations of solvents in laundry wastewaters : addressed above (i.e., the existing methodology is intended to isolate effects from shop and printer towels)

.

• Comment (0461

– TRSA, page 13): Industry Data. In response to the NODA, TRSA conducted a survey of its membership seeking data representation of current conditions in the industry. 8 This data is business sensitive and was compiled only for purposes of responding to this NODA. Data collected via the survey included the following dat a points for the years 2005

- 2009:

o The laundry location;

o The sludge disposal location;

o Whether sludge was sent to a lined or unlined landfill;

o The pounds/ year of both shop towels and printer towels processed;

o The gallons of washwater used per pound of towe l;

o Total sludge concentration in ppmw for PCE, TCE, Methylene Chloride, Benzene, and 1, 1, 2

- trichloroethane 9

o Sludge TCLP data in mg/l for the same solvents; and

o Solvent concentration in mg/l from wash water before pre

- treatment

Eleven TRSA member compani es responded, providing data from 271 industrial laundry facilities and 569 location

- years of data points. These 271 facilities represent almost 90% of all facilities engaged in processing shop towels or printer towels. Using these data, independent expert Dr. Ranajit Sahu performed both a deterministic calculation for the estimated loading of PCE from laundry sludge, replicating EPA’s deterministic method, including EPA’s assumptions, and a Monte Carlo analysis. For the unit conversion and the sludge parti tioning values, Dr. Sahu used the same values

8 The background data used to run both the deterministic and Monte Carlo calculations are attached hereto as “TRSA Survey Data and Summary”, Exhibit “B” and “Crystal Ball Report Using TRSA Data”, Exhibit

“C”.

9 Given EPA’s conclusion that PCE was the only solvent posing a potentially unacceptable risk for laundry sludge, the following analysis pertains only to PCE.10 as EPA. For the other factors

– pounds of shop towels washed at a site, shop towel water concentration, pounds of printer towels washed at a site, printer towel water concentration, probability that laundry man ages printer towels in addition to shop towel, gallons of washwater used per pound of towel, and the number of

laundries/landfill

– Dr. Sahu used TRSA survey data. For the deterministic approach, TRSA’s calculations represent the average for each data poin t used.

RESPONSE : We have made a case

- by

- case evaluation of the data collected and provided by the commenter . EPA’s use of the data is described below.

The pounds/year of both shop towe ls and printer towels processed

. The commenter’s data includes appro ximately 568 data points for shop towels and approximately 119 data points for printer towels. This data has advantages and drawbacks in comparison

to the data used in the Landfill Loa dings R eport. A primary advantage is that it is more recent (2005 to 200 9) than the 1990s data used in the Landfill Loadings R eport. It also appears to incl ude more facilities (271 as identified by the commenter), versus approximately 141 used in the Landfill Loadings R eport. A drawback to the commenter’s data is that it appea rs to include data for multiple years for a single facility, with no method to distinguish which data are from a single facility. Therefore

it may bias the results towards those facilities providing multiple years of data over a facility providing a single year of data. Nevertheless, the advantages outweigh the disadvantages in this instance . Therefore, the landfill loadings calculations have been modified by including the commenter’s data for the pounds/year of shop towels and printer towels processed

. In addition, Section 3.3.1 of the Landfill Loadings Repor t is modified by describing the data used.

The gallons of washwater used per pound of towel

. The commenter provided 147 data points for this parameter. Similar advantages and limitations apply to this parameter as with the pounds of shop and printer towels processed. In addition, the Landfill Loadings Report previously considered this value as a constant (Section 3.3.4). Based on the new data submitted, t he landfill loading calculation s are modified by including

these data as a distribution (t he empirical data w ere best

- fit to a lognormal

distribution )

. In addition, Section 3.3.4 of the Landfill Loadings Repor t is modified by describing the data used.

Solvent concentration in mg/l from washwater before pre

- treatment

. The commenter provided 29 data points for tetrachloroethylene in washwater. The advantage of this

data is that it more recent than the 1990s ELG data. However there are significant

drawbacks with the data:

• The ELG data used in the Landfill Loadings R eport are representative of washwater generated from shop or printer towels when washed alone (Landfill Loadings Report Section 3.3.3). The commenter does not specify the source of

the sampled washwater

. Based on its comments and concerns above t hat the concentrations used in the Landfill Loadings Report are high because they are taken from a process washing only shop or printer towels, we assume that11 these concentrations reflect washwater generated from shop and printer towels plus other textiles

. As described previously, the calculation in the Landfill Loadings R eport attempts to isolate the effect from shop and printer towels

. We prefer to use data representative of washwater generated from the washing of shop and printer towels only to estimate the loadings of treatment sludge derived from laundering solvent

- contaminated wipes . Therefore, we did not incorporate the concentrations provided by the commenter in the final analysis.

• The ELG data used in the Landfill Loadings R eport are based on six l aundries washing shop towels and three laundries washing printer towels (Landfill Loadings Report Section 3.3.3). It is not clear from the commenter’s data whether the concentration data represents multiple years from a single site , in

which case the numbe r of sites represented by the commenter’s data may be significantly less than 29

. Therefore, the number of sites represented by the ELG data set may be comparable to the number of sites represented by the

commenter’s data.

• The commenter did not provide any details on how the washwater samples were obtained or analyzed, nor were any QA or QC information provided. Therefore, EPA dec i ded not to use these data.

For these reasons, the tetrachloroethylene data provided by the commenter are not

used in the Landfi ll Loadings Repor t.

Other Data Identified by the Commenter

. The commenter identifies additional data elements as part of its survey:

o The laundry location;

o The sludge disposal location;

o Whether sludge was sent to a lined or unlined landfill;

o Total sludge concentration in ppmw for PCE, TCE, Methylene Chloride, Benzene, and 1, 1, 2

- trichloroethane

o Sludge TCLP data in mg/l for the same solvents.

However, t hese results were not provi ded by the c ommenter and could not be

evaluated.

• Comment (0461

– TRSA, page 14

- 15 ): Deterministic Analysis. The results of this

deterministic calculation are reflected in the Table below.

[Table

- Calculations for Estimating Landfill Loading of PCE from Laundry Sludge]

Using EPA’s method, and substituting TRSA’s more recent an d robust data as described above, TRSA contends that EPA has overestimated PCE loading into a landfill by a factor of 417, with TRSA estimating that the kg/year of PCE going to

landfill to b e 0.064 kg/yr not 26.74 kg/yr. Of course, reducing the ELLR by a f actor of 417 negates any potential excess risk for laundry sludge that EPA has estimated,12 for both the lined or unlined landfill with one possible exception

– the potential risk at

the 90 th percentile for PCE at an un unlined landfill using the combined wi pes and sludge data ( see Comparison Background Document at 6, Table 1, estimated risk ratio of 530 for PCE under the combined scenario). 10 Most significantly, the potential risk ratio of 1.1 for PCE in a lined landfill under a combined wipes plus sludge sce nario, is negated by TRSA’s data

, and becomes even less of a risk in light of the fact that of the 1.1 ratio, only 0.2 is attributed to laundry sludge. Qualitatively then, given that EPA has overestimated by a factor of 417, it is reasonable to conclude th at laundry sludge poses no excess risk for PCE or any other solvent, especially in a lined landfill disposal scenario.

Other aspects of TRSA’s data further confirm that EPA has significantly overestimated the potential risk associated with laundry sludge . Overall, TRSA’s data indicates that fewer reusable towels (printer or s hop towels) are being processed by industrial laundries in a given year than EPA has estimated (312,893 lb/yr shop towels versus EPA’s estimate of 465,000 lbs/yr). There is an even mo re dramatic decline in the use of printer towels. (EPA estimates of 429,000 lb/yr versus TRSA survey data showing 214,595 lb/yr). TRSA data regarding this variable were received from as far back as 2005, indicating that the industry reduction in printer to wels processed is not due solely to the economic slowdown of the past 15 months. In addition, where EPA estimated a 36% probability that a given facility is washing both shop towels and printer towels, TRSA’s data

– for which it received 569 data points

– indicates that there is an overlap, on average, for only 21% of responding facilities. For the concentration data, TRSA data are based upon 29 data points; EPA used only three data points.

Regarding the volume of washwater, TRSA’s data confirms the gener al pattern seen throughout the industry ( see Section II C.2 above ) that facilities are increasingly using less water per pound of textile without impact to sludge content. TRSA’s 148 data points show that on average laundries are using 2.05 gallons/pound o f towel, as opposed to 2.28 gal/lb as used by EPA based upon 2002 data.

Finally, and most importantly, the TRSA survey results indicated that the majority of facilities are using lined landfills. TRSA’s data are reflective of the general trend over the p ast 20 years away from unlined landfills. Further, on average, the TRSA data show that a given landfill accepts sludge from only one laundry facility and not multiple facilities. EPA’s contractor estimated that the number of laundries to a given

landfill w as 1.7, almost twice what TRSA’s data show. Regardless, the overestimation of PCE loading into either an unlined or lined landfill by a factor of 417 based on a much more robust and current data set, alone eliminates the notion that any of the solvents pos e any potential excess risk for laundry sludge.

10 See above, Sectio n II.C, for TRSA’s argument why it is incorrect to estimate risk using a combination of disposable wipes data and laundry sludge data.13 RESPONSE : Most of the comments regarding various input parameters are

discussed previously

. These include the quantity of towels washed, washwater concentration, and washwater volume.

The fraction of facili ties washing printer towels versus shop towels was calculated by the commenter as 21% (i.e., 119 data points for printer towels/568 data points for shop towels). The commenter’s data may not be a true reflection of facility count, because a single facility can be represented by multiple data points. To provide consistency with the other uses of th e data provided by the commenter , however, the landfill loadings calculations are revised to include this percentage calculated by the

commenter.

The number of la undries using a single landfill is also an input parameter. The commenter states, on average, that a given landfill accepts sludge from only one laundry facility and not multiple facilities. We disagree that this is a reasonable average value because, at a minimum, a given landfill will accept sludge from a single laundry facility ( i.e.

, this value can never be less than one)

. The supporting data used by the commenter to check this conclusion was not provided. Therefore the parameter value used in the Landf ill Loadings Report is unchanged.

The results following incorporation of the above changes are included in Section 3.4

of the revised Landfill Loadings R eport.

The commenter’s claim that the survey shows that the “majority” of laundry facilities dispose of their sludge in lined landfill is not sufficient to demonstrate that there are no potential risks from disposal in unlined units. The term “majority” is vague, and the specific number using lined landfills or the underlying data were not presented.

None theless, we modeled both an unlined and composite

- lined landfill scenario to assess the full range of potential risks. The Agency found that disposal of wipes in composite

- lined landfills was a necessary condition for the exclusion to adequately protect hu man health and the environment.

• Comment (0461

– TRSA, page 15): Monte Carlo Analysis. After conducting the deterministic calculation, the same data sets used were also used to conduct a Monte

Carlo analysis for PCE only, using Crystal

- Ball, the same soft ware used by EPA’s contractors. The Monte Carlo analysis using TRSA’s data confirms the conclusion

reached in TRSA’s deterministic calculation.

As shown in the attached Crystal Ball report, 200,000 trials were run. Lognormal

distributions were selected fo r each of the variables with the respective distributional parameters. In most cases, the lognormal distribution was the one selected by the program as the best fit. In a few cases, the lognormal was the second best fit, very close to the one selected by t he program. However, from a conceptual standpoint, it is more likely that the data are lognormally distributed, which is why it was selected. The results did not materially change if the other distribution (for example, Weibull) was selected. In the report , cell K5 refers to pounds of shop towels; cell K6 refers to14 the PCE concentration in wash water; cell K7 ref ers to pounds of printer towels; and cell K10 refers to the gallons of wash water per pound of towel, of either kind.

The Monte Carlo analysis sh ows the respective sludge loading results for PCE as follows: 0.019 kg/yr at the 50 th percentile and 0.171 kg/yr at the 90 th percentile. In comparison, the respective EPA

- estimated values were 23 kg/yr at the 50 th percentile

and 170 kg/yr at the 90 th perce ntile. EPA’s Monte Carlo analysis, therefore, over

estimates the sludge loading to a landfill by a factor of 1202 at the 50 th percentile and by a factor of 991 at the 90 th percentile.

Given the results from TRSA’s more current and robust data, it is clear that PCE

containing laundry sludge does not pose any potential excess risk.

RESPONSE : R esults of the revised analysis are included in Section 3.4 of the

revised Landfill Loadings R eport. These results incorporate the previously discussed changes to the i nput parameters. The revised sludge r esults for 20 chemicals (i.e., not limited to perchloroethylene) are included. These 20 chemicals are the ‘F

- listed solvents’ as described in Section 1.2 of the Landfill Loadings Report. As described previously in respo nse to TRSA’s comments, we did not adopt all of the changes suggested by the commenter. Using the updated data on the pounds of towels processed per year and the resulting washwater used lowered the mass loadings calculated for sludges generated by the lau ndries by about 50%. These changes are presented in the final Landfill Loadings Report.