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California Refional Water ualit <br /> y ontrol Board >�� <br /> Central Valley Region <br /> Steven T.Butler,Acting Chair ,y� <br /> Winston H.Hickox <br /> Secretaryfor Sacramento Main Office Gray Davis <br /> Environmental Internet Address: http://www.swrcb.ca.gov/—rwgcb5 Governor <br /> Protection 3443 Routier Road,Suite A,Sacramento,California 95827-3003 <br /> Phone(916)255-3000•FAX(916)255-3015 <br /> 010 <br /> TO: Wendy L. Cohen FROM: Wendy Wyels <br /> Senior Engineer Site Cleanup Unit <br /> DATE: 18 February 1999 SIGNATURE: 1 jr <br /> 1 <br /> UJJJ <br /> SUBJECT: REVIEW OF THE DRAFT PHASE 77 IRA, LINCOLN CENTER, STOCKTON, SAN <br /> JOAQUIN COUNTY <br /> I have reviewed the 27 January 1999 Draft Phase II Interim Remedial Action Detail Plan prepared by <br /> Levine-Fricke-Recon (LFR) for Lincoln Center in Stockton. The report provides interim cleanup levels <br /> for soil vapor, documents a soil vapor extraction pilot test, and describes various technologies to <br /> remediate the soil vapor, and provides a conceptual design for a full-scale vapor extraction system. The <br /> report is well written and comprehensive. My comments are as follows: <br /> 1. Section 3.0 provides the Proposition 65 "no significant risk level" for indoor air exposure to PCE <br /> but does not give the level calculated by LFR. It would be helpful if the report also provided <br /> information about how and when actual indoor air exposure was measured at the site and the <br /> concentrations of PCE detected. <br /> 2. Section 3.0 should list all exposure pathways which were considered before it was decided that <br /> inhalation of soil vapor was the only complete exposure pathway. It should be noted that although <br /> consumption of groundwater is not a current exposure pathway, it must be considered a future <br /> exposure pathway in the health risk assessment. <br /> 3. I fully support LFR's statement that it would be more practical and economical to construct a full- <br /> scale soil vapor extraction (SVE) system at this time versus installing a system limited to "hot <br /> spots" or areas of immediate concern to human health. <br /> 4. Section 3.3 states that a target remedial concentration of 150 ug/1 PCE in the soil vapor has been <br /> selected. I have two comments about this selection: <br /> a. The value of 150 ug/1 can only be considered an interim value because the human health risk <br /> assessment has not yet been completed, the target remedial concentration does not take into <br /> account the additive toxicity of the multiple chemicals in the soil vapor, and LFR used the <br /> Department of Health Services' Maximum Contaminant Level (MCL) for PCE to calculate <br /> impacts of the soil vapor on water quality. However, Board policies state that the most <br /> applicable water quality criterion for PCE is the cancer potency factor of 0.7 ug/l. This is an <br /> order of magnitude lower than the MCL of 5.0 ug/1. <br /> California Environmental Protection Agency <br /> pia <br /> Recycled Paper <br />