September 14, 2012

Mr. Marcus Aguilar Chemical Control Division (7405M) Office of Pollution Prevention and Toxics Environmental Protection Agency East Building 1200 Pennsylvania Avenue NW Washington, DC 20460

– 0001 ( via e

- mail: Aguilar.Marcus@epamail.epa.gov )

Re: Enforceable Consent Agreement Development for Two Cyclic Siloxanes (EPA Docket Number: EPA

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– 0209 )

Dear Mr. Aguilar :
The American Cleaning Institute (ACI) is pleased to provide the following comments with respect to the proposed Enforceable Consent Agreement (ECA) for two cyclic s iloxanes : octame thylcyclotetrasiloxane (D4) and d ecamethylcyclopentasiloxane (D5; EPA Docket Number: EPA

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– 0209 ). ACI is an Interested Party to the development of the ECA.

We have reviewed the documents available in the docket including the recent EPA Siloxane Monitoring Proposal (September 6, 2012) and the August 3, 2012 letter from the Silicones Environmental, Health and Safety Council ( SEHSC ) including the July 2012 Final Report entitled Recommendation of Number of Sites to Sample for Validation of the D4 and D5 Publicly

- Owned Treatment Works Conceptual Site Model

. The agency indicated in its September 6, 2012 proposal that the ECA “ should support a risk assessment that wi ll allow EPA to make a determination on whether or not risk management action is needed to address the release of siloxanes in the environment

. ” Further, the agency has concluded that the SEHSC proposal would not provide adequate information for the agenc y to conduct a risk assessment. It is not possible to confirm the agency’s conclusions based on the information available. EPA has not indicated what approach is will use in conducting its risk assessment and it has not reported what data it has at its d isposal or where gaps exist.

It is our observation from the several public meetings on the ECA and related discussion and documents in the docket that the scope of the ECA is solely with respect to environmental concentrations of D4 and D5

, with an empha sis on freshwater streams receiving treated municipal and industrial wastewater effluent and associated sediments. In order to characterizeMr. Marcus Aguilar Page 2 of 3 September 14, 2012

environmental concentrations efficiently across the entire United States, we recommend that a modeling approach be used initially and that environmental monitoring be conducted to confirm the modeled results are similar or, at a minimum, conservative in their estimation. Use of environmental exposure models allows for insights as to where highest concentrations may oc cur and where the greatest risks may be. Moreover, if conservative environmental monitoring does not reveal an unacceptable environmental risk and there is a wide margin of safety, additional environmental monitoring may not be necessary at all.

We note t hat the SEHSC proposal included a conceptual site model and their monitoring approach is predicated on collecting data to support that model. We believe their monitoring approach is well conceived to achieve that objective. In addition, in a March 2012 p resentation to the agency, SEHSC stated that they used EPA’s E

- FAST model to predict surface water concentration distributions and subsequently predicted distribution of surface water concentrations of D4 and D5 across the US via ACI’s i STREEM ® model. Whi le they did not include the results of their modeling in their documents, such results combined with existing publicly available occurrence data might render additional monitoring completely unnecessary.

The agency’s proposal of September 6, 2012 does not contain a conceptual model which would incorporate the data it proposes to collect. We recommend that the agency provide such information so that the benefit of its proposed sampling plan is readily apparent.

With respect to the parameters that the agency has chosen in order to populate its sampling plan matrix for municipal wastewater treatment sites, we agree that in

- stream dilution and wastewater treatment technology are important. We agree that sites should be selected based on a variety of dilution r ates for municipal wastewater effluent and that the three tiers proposed by the agency may be appropriate. Likewise, we believe a focus on activated sludge treatment is most appropriate as 80% of municipal wastewater is treated by this method. However, w hile we agree that lagoons are a very common treatment technology , they present the poorest type of treatment

– often being associated with increased levels of total suspended solids, biologica l oxygen demand (BOD) and ammonia in treated effluent when comp ared to other treatment technologies

. Further, discharg e at lagoon treatment facilities is often flow

- dep endent. That is, it is common during low flow months for lagoons not to discharge to receiving surface waters. Hence, if lagoons are to be included in a monitoring program, an understanding of where continuous

- flow, well

- operated (no significant non

- compliance events) facilities occur will be necessary

. The agency also has proposed a population

- POTW flow parameter that appears to be indicative of w astewater influent concentration. Based on recent field experience , we have observed that the design flow of wastewater treatment plants correlates very closely to the population served by a facility (Mudge, 2012

, Figure 35, page 47)

. 1 Notwithstanding that correlation, it is prudent to expect that wastewater influent concentration may vary significantly. However, there are a number of parameters that might affect influent concentration including geographical use patterns of consumer pro ducts, consumer use patterns, daily water use patterns, seasonal weather patterns and local infrastructure among others. In fact, we observed during the same research 1 that there may be a correlation between influent concentration and effluent dilution ba sed on

1 http://www.aciscience.org/docs/Fatty%20Alcohols%20by%20WWTP%20and%20Ecoregion

- FINAL.pdfMr. Marcus Aguilar Page 3 of 3 September 14, 2012

local meteorology

– we observed high influent concentrations in Oklahoma during a prolonged drought (and low stream flows), and low influent concentrations in Oregon during a period of excessive rain (and high stream flows). Any attempt to predict influent concentration based on these and other variables would likely not lead to meaningful results, but more to the point, the single parameter that the agency has chosen (population

- POTW flow) is not likely to be informative. Further, many wastewater treatment plants are specifically designed to dampen spikes of influent chemicals through the use of flow equalization basins. We recommend that this parameter not be used in the site selection process but that the focus of site selection remains
on waste water treatment technology and effluent dilution.

We appreciate EPA’s consideration of our comments and request that they be included in the docket ( EPA

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– 0209 ) and that they be circulated to all interested parties in advance of the next meeti ng scheduled for Thursday, September 20, 2012.

Sincerely

,

Paul C. DeLeo, Ph.D. Senior Director, Environmental Safety

cc: Robert Jones, USEPA ( jones.robert@epa.gov ) Karluss Thomas, Silicone Environmental Hea lth and Safety Council ( kthomas@sehsc.com )