UNITED STATES ENVlRONSJENTAt PROTECTION AGENCY WASHINGTON, D.C, 20460
Mr, Stephen P. Risotto Senior Director American Chemistry Council 700 Second Street, NE Washington, D.C. 20002
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OFFICE OF SOLID WASTE AND EMERGENCY RESPONSE
NOW THE OFFICE OF LAND AND EMERGENCY MANAGEMENT
Dear Mr. Risotto;
Thank you for meeting with the Office of Land and Emergency Management (OLEM) representatives on June 22, 2017, and your follow-up letter o f June 28, 2017. in both the meeting and your letter, you raised concerns regarding the U.S, Environmental Protection Agency's (EPA) recommendation to consider early or interim cleanup actions to address indoor air exposure to trichloroethylene (TCE) at contaminated sites. Specifically, your concerns involved the scientific data behind and the implementation cost associated with the Office o f Superfund Remediation and Technology Innovation (OSRT1) August 27, 2014, memorandum. Compilation o fInformation Relating to Early/Interim Actions at Superfund Sites and the TCE IRIS Assessment, Based on these concerns, you requested that the EPA suspend implementation of the 2014 memorandum and related regional memoranda until the completion and consideration o f an ongoing TCE risk evaluation by EPA's Office Chemical Safety and Pollution Prevention (OCSPP).
With respect to use o f toxicity information in support o f OLEM risk assessments, OLEM 's use o f the TCE Integrated Risk Information System (IRIS) assessment, first issued in 2011 and reaffirmed in 2016, is consistent with longstanding OLEM policy as reflected in the OSRTI memo cited above. Following the Office o f Solid Waste and Emergency Response Directive 9285.7-53, when available, IRIS assessments are the preferred source of human health toxicity values. Consistent with Of,EM policy, the 2014 memorandum did not direct regions to utilize a chronic reference concentration for short-term exposure. Rather, the 2014 OSRTI memorandum restated the findings o f the 2011 IRIS evaluation and cited existing guidance about the use of early or interim actions and consideration o f non-cancer health effects. We are aware o f the ongoing hazard assessment for TCE that is currently being conducted by OCSPP which may incorporate additional data not considered by the IRIS program. When that assessment becomes available, OLEM will consider whether it would be appropriate to update our assessments for TCE to reflect the findings of the OCSPP assessment.
After canvassing EPA's regional offices, we have been unable to confirm that there has been a significant increase in remediation costs at TCE-contaminated Superfund sites as a result o f the 2014 policy. A review o f removal actions for sites with TCE, as recorded in EPA's Superfund Enterprise Management System (SEMS) database, failed to find any difference in the number o f removals in the three years preceding the memorandum and the three years since the memorandum was issued (an
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average o f 11 per year). Additionally, the EPA is not aware o f an increase in the costs o f employing engineered exposure controls (e.g.; subslab depressurization systems) as an interim response action for vapor intrusion.
While OLEM appreciates your concerns regarding EPA's approach for indoor air exposure to TCE from vapor intrusion, our 2014 memorandum is simply a compilation o f existing information and guidance. We failed to find evidence o f any significant cost impact associated with the memorandum. Since it is consistent with longstanding OLEM guidance and provides information useful to EPA regions, we currently plan to keep the 2014 memorandum and related regional memoranda in place. If new information becomes available, we will consider whether updates are appropriate.
Sincerely
Patrick Daffis Deputy Assistant Administrator
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