Karluss Thomas 

Senior Director 

UNITED STATES ENVIRONMENTAL PROTECTION AGENCY 

WASHINGTON, D.C. 20460 

OCT 31 2014 

Silicones Environmental, Health, and Safety Center 

American Chemistry Council 

700 2nd Street NE 

Washington, DC 20002 

Re: Draft Study Plan for 4 Direct Discharge Sites 

OFFICE OF CHEMICAL SAFETY 

AND POLLUTION PREVENTION 

Testing Consent Order for Octamethylcyclotetrasiloxane (D4) CASRN: 556-67-2 

40 C.F.R. 799.5000 

EP A-HQ-OPPT -2012-0209 

Dear Mr. Thomas: 

This letter is in response to your August 8, 2014 letter submitting a draft study plan for four 

direct discharge sites as identified in the April4, 2014 Enforceable Consent Agreement (ECA) 

for Environmental Testing for Octamethylcyclotetrasiloxane (D4) between the U.S. 

Environmental Protection Agency and five manufacturers of the chemical. As you know a 

complete Study Plan was due August 2, 2014 (as per ECA paragraph IX.A, no more than 120 

days after effective date), with a subsequent Quality Assurance Project Plan (QAPP) due October 

1, 2014 (as per ECA paragraph IX.A, no more than 180 days after effective date). The ECA 

specified that testing would occur at four direct discharge sites and ten third party waste water 

treatment plants (WWTPs ). While the Study Plan as submitted has not fully fulfilled the 

requirements of the ECA, the agency has some initial comments on the Study Plan that are 

described below. 

1. General Process Description of Industrial Plant Operations for Each Site 

The ECA states (Appendix 1, page 20), "A general process description of the industrial plant 

operations involving D4 shall be provided. A more detailed description, including a written 

narrative and process flow diagram(s) ofthe wastewater treatment system employed at the 

sites shall also be provided (e.g., at a minimum consistent with what was provided in each 

facility's discharge permit application." 

The general process descriptions provided for the Momentive Performance Materials (MPM) 

Friendly (Study Plan, section 9.2) and Waterford (Study Plan, section 10.2) sites are not 

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adequate. These descriptions do not sufficiently describe the processes that contribute D4~ 

containing wastewaters to the on~site WWTP. Thus, it is not clear how D4~containing 

wastewaters are generated at these sites. 

Additionally, the WWTP process flow diagrams (PFDs) provided for Wacker- Adrian 

(Study Plan, figure 7-2), MPM- Friendly (Study Plan, figure 9-2), and MPM- Waterford 

(Study Plan, figure 1 0~2) are of a poor scan quality and are difficult to read. The PDFs cannot 

be adequately reviewed in their current visual quality. 

2. Normal Operating Conditions 

The ECA (Appendices 1, 4, 5, 7 and 8) states, "Samples shall be collected during normal 

plant operations and during such times that effluent flow rates from the wastewater treatment 

system are representative of the normal plant operations." The ECA further states that, "the 

criteria or means that are used by the facilities to determine normal operating conditions will 

be documented in the site~specific Sampling Plans." 

The Study Plan includes a discussion of normal operating conditions for each of the four 

direct discharge sites and establishes that ERM will verify that the WWTPs are functioning 

under normal operating conditions and flow rates prior to sampling (sections 7.2.3, 8.2.3, 

9.2.3, and 10.2.3). Although these parameters are important, greater detail is needed. 

Specifically, process equipment that feeds D4 containing wastes to the WWTP should also be 

operating under normal conditions as well. This point is made by the MPM- Waterford site 

(Study Plan, section 10.2.3) and should also be included in the respective sections for the 

other three direct discharge sites. 

The WWTP process flow diagrams provided for Wacker- Adrian (figure 7~2), MPMFriendly (figure 9~2), and MPM- Waterford (figure 10~2) are of a poor scan quality and are 

difficult to read. The PDFs cannot be adequately reviewed in their current visual quality. 

3. Site Characterization 

Sections 10.1 and 10.2 (regarding MPM- Waterford) of the draft Study Plan make some 

statements that require further clarification: 

a. Section 10.1 states that Outfall 020 is on the Hudson River's east bank. However, it 

appears that the outfall is on the west bank based on Figure 1 0~ 1. 

b. Section 10.2.2 makes reference to Outfalls 021 and 022, but makes no mention of Outfall 

020 (the outfall to be sampled). It is unclear if the references to Outfalls 021 and 022 are 

correct, or if one of these outfall numbers should be 020. 

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4. Sampling Point 

a. The ECA requires that surface water, sediment and biota sampling locations shall be 

collected as close as reasonably possible to the effluent outfall provided adequate mixing 

of the discharge and receiving water has occurred (Appendix 8). SEHSC in its Study Plan 

has noted problems with establishing adequate mixing at some facilities and proposed 

using 100m as the sampling location. Please revise text to include the rationale for how 

the proposed approach satisfies the requirements of the ECA. 

b. Alternatively, at sites where adequate mixing cannot be established EPA would consider 

an approach where 3 required samples could be collected incrementally downstream of 

the outfall (e.g., at 100m, 500 m and 1000 m) instead of at a single location at lOOm. 

This approach may bracket the point where adequate mixing has occurred. 

c. With respect to the remaining sites, EPA expects that sampling locations are to be 

determined by establishing the point where adequate mixing has occurred. The defined 

mixing zone within the NPDES permit or by calculating the size of the mixing zone with 

an EPA approved method may be useful methods to establish adequate mixing. One 

problem with removing the use of the mixing zone methodology based on the four direct 

discharge sites in the program is that the full set of sampling sites is not yet known. Given 

that the Hudson and Ohio Rivers likely will be the largest rivers in the sampling plan, it 

may be premature to decide that the mixing zone technique is broadly inapplicable. If the 

other water bodies are more in line with the River Raisin site (Adrian, MI) then the 

distance to complete mixing may be useful for the following ten sites. 

d. The Study Plan (section 7 .2.2) states that the effluent is discharged via outfall to a 

wetlands zone that conveys the waste water to the River Raisin. This is likely an unusual 

circumstance and consideration should be given to measuring the sediment 

concentrations in the affected wetlands. If there are releases of 04, a significant portion 

may be retained in this wetland environment. EPA recognizes that this would not be how 

the Parties have typically conceptualized the monitoring location specified by the ECA 

but would likely generate more useful exposure assessment information. See photograph 

4 in Figure 7-6 for more details. 

5. Biota Collection 

a. The ECA (Appendix 8, page 48) states, "Biota sampled shall include benthic species 

collected in sediment of the receiving water body and two species offish, if practicable, 

of different trophic guilds, in the receiving water body." In the submitted material it is not 

apparent that this will be a priority as abundance is repeatedly listed as a criterion for fish 

sample collection. However, it is not necessary to collect a significant number of larger 

fish to have sufficient tissue mass for analysis. Once the threshold for mass of tissue 

required for analytical needs has been met, the goal of collecting fish from two different 

trophic levels should supersede the abundance criterion in all sections of the sampling 

plan (for each site), in the standard operating procedures and in the QAPP. 

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b. The collection of benthic invertebrates should avoid species such as mussels, clams or 

crayfish to provide consistency across sites in the program due to identified differences in 

collection permits. 

6. Omissions or errors in the submitted documents 

a. Study Plan section 2.2.Table 2-1 is listed as having the contact information for the 

signatory companies. Table 2-1 was not include with the submission. 

b. Study Plan section 3.1, Table 3-1 is listed as having a list of personal-care products that 

can be used by the samplers, but table 3-1 does not contain that information. 

c. Include a copy of the NPDES permits for all sites in the program. 

d. Study Plan sections 7.4 & 8.4, the literature sources for the fish species that may be 

present need to be identified for the Adrian, MI and East Carrollton, KY sites. Currently 

"a review of various literature sources" or "the results of a 2008 biological study" are the 

only references. The literature sources should be identified and added to the references 

list. 

EPA asks the Signatory Companies to continue its efforts to secure the cooperation of third party 

WWTP operators, as well as to continue to work with EPA to find a path forward to address the 

WWTP issue. If you have any questions, please contact Heather Njo of my staff at 202-564-2574 

or at njo.heather@epa.gov. 

Sincerely, 

Wendy Cleland-Hamnett, Director 

Office of Pollution Prevention and Toxics 

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