Karluss Thomas 

Senior Director 

UNITED STATES ENVIRONMENTAL PROTECTION AGENCY 

WASHINGTON, D.C. 20460 

MAY 1 3 2015 

Silicones Environmental, Health, and Safety Center 

American Chemistry Council 

700 2nd Street NE 

Washington, DC 20002 

OFFICE OF CHEMICAL SAFETY 

AND POLLUTION PREVENTION 

Re: Enforceable Consent Agreement for Octamethylcyclotetrasiloxane (D4) (CASRN: 556-

67-2) 

Dear Mr. Thomas: 

This letter follows the April 30, 2015, conference call between the U.S. Environmental 

Protection Agency, the Silicones Environmental, Health and Safety Center (SEHSC), and 

Russell Mait of the Evonik Corporation regarding the indirect discharge survey results used to 

identify potential wastewater treatment plant (WWTP) sites to fulfill the enforceable consent 

agreement (ECA) referenced in the subject line above. Following the call, EPA reviewed the 

completed surveys and accompanying summary table provided by SEHSC. 

The ECA specifies for the indirect discharge sites that: 

All wastewater treatment sites selected for monitoring must be currently processing 

wastewater from one or more industrial sites known to be a 04 processor or formulator as 

documented through industrial user surveys or by other readily available information. 

Section 3 of The Toxic Substances Control Act specifies that the term "process" means: 

the preparation of a chemical substance or mixture, after its manufacture, for distribution 

in commerce-( A) in the same form or physical state as, or in a different form or 

physical state from, that in which it was received by the person so preparing such 

substance or mixture, or (B) as part of an article containing the chemical substance or 

mixture. 

Based on the survey results that SEHSC provided, however, EPA is not able to substantiate that 

the processing of D4 or the formulation of D4-containing products is occurring at many of the 

industrial sites. Our review of the survey results appear to indicate that many of the industrial 

sites are not formulating or processing D4. Based on the survey results submitted, EPA believes 

that the Gresham. and Wichita WWTP sites proposed for monitoring may not meet the conditions 

lnterne1 Address (URL)· http /lwww epa gov 

Recycled/Recyclable • Prmted with Vegetable 011 Based Inks on 100% Postconsumer Process Chlorine Free Recycled Paper 
specified by the ECA. EPA welcomes the opportunity to discuss this fm1her during the May 20, 

2015, conference cal I. 

SEHSC asserted during the April 30th call that it would provide additional information that 

would demonstrate that the indirect sites selected meet the requirements specified in the ECA, 

including, but not limited to, a: 

• Value chain analysis that quantifies the D4 concentration in substances typically 

processed or formulated at the surveyed industrial sites; 

• Process flow diagram depicting how D4 gets into the effluent; and 

• Rationale for the indirect discharge survey and analysis of results demonstrating that 

the proposed wastewater treatment plant locations meet the D4 ECA criteria for 

selection of indirect discharge sites. 

Finally, EPA remains concerned that SEHSC has yet to provide the rationale for how the 

proposed sampling point of l 00 meters will satisfy the data requirements of the ECA. The ECA 

specifies that "each site specific sampling plan will identify where the effluent and receiving 

stream are adequately mixed and the basis for the determination." In order to comply with the 

terms of the ECA, the agency recommends that SEHSC: 

1. Present available regulatory determinations, modeling (as was done for the direct 

discharge locations), and information from visual inspection on mixing zones for each 

site. 

2. Based on this information and any other site specific factors, provide a rationale for 

the sampling point where the effluent and receiving stream are adequately mixed at 

each site. 

EPA hopes the scheduled conference call with SEHSC on May 20, 2015, will lead to the 

eventual resolution of all outstanding issues discussed to date, including SEHSC's plan for 

complying with the ECA with respect to the full number of test sites. 

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

njo.heather@epa.gov. 

I 

Sincerely, 

~Mi 0_DJQ,-

Maria J. Doa, Ph.D. 

Director 

Chemical Control Division