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.o <br /> San Joaquin County <br /> PAWN. Environmental Health Department DIRECTOR <br /> Donna Heran, REHS <br /> r.` 600 East Main Street <br /> Stockton, California 95202-3029 PROGRAM COORDINATORS <br /> Robert McClellon, REHS <br /> ..r: Jeff Carruesco,REHS, RDI <br /> Cq' ......•�i�P Website: www.sigov.org/ehd Kasey Foley,REHS <br /> /FOR <br /> Phone: (209)468-3420 <br /> Fax: (209) 464-0138 <br /> 07 January 2010 <br /> Mr. Carl W. Knowles, Successor Trustee <br /> Knowles Family Trust Agreement <br /> P.O. Box 640 <br /> Woodbridge, CA 95258 <br /> Subject: 102 S Wilson Way <br /> Stockton, CA <br /> The San Joaquin County Environmental Health Department (EHD) has received and reviewed Soil <br /> Vapor Investigation & Vapor Intrusion Risk Evaluation, dated 31 December 2009, prepared by your <br /> consultant Ground Zero Analysis (GZA). In the report, GZA: <br /> • Reported the analytical results obtained from six soil gas samples collected from <br /> approximately 5 feet below surface grade (bsg), <br /> • Presented a comparison of those results to the San Francisco Bay Regional Water Quality <br /> Control Board's Environmental Screening Levels (ESLs); and <br /> • Reported the results of a Phase II Johnson and Ettinger (J&E) model analysis of the data <br /> that failed to pass the ESLs. <br /> GZA found that the Tier II analysis of the acquired soil gas data was favorable for the site; no <br /> unacceptable cancer risk or health hazard was identified utilizing site-specific data in the J&E <br /> model. GZA recommended continued semi-annual monitoring and sampling of the site wells. <br /> Providing that the data and assumptions utilized to evaluate the risk and hazard posed by vapor <br /> intrusion are correct, the EHD concurs with the GZA conclusion that hydrocarbons in soil gas <br /> present an insignificant health risk and hazard through vapor intrusion into the structures on the <br /> subject site. The EHD also concurs with the recommendation to continue semi-annual monitoring <br /> and sampling of the site wells. The monitoring schedule put forth in the EHD letter dated <br /> 23 February 2009 should be followed. You are still to meet the directives and deadline issued to <br /> you by the EHD by letter dated 23 December 2009. Questions or comments may be directed to <br /> Nuel Henderson at (209) 468-3436. <br /> Sincerely, J <br /> Nuel C. Henderson, Jr., PG Adrienne Ellsaessar, REHS <br /> Engineering Geologist Acting Program Coordinator <br /> C: James Barton, CVRWQCB 11020 Sun Center Dr. #200, Rancho Cordova, CA 95670 <br /> Gregory Stahl, GZA, 1714 Main Street, Escalon, CA 95320 <br /> Mohammid Asghar, 601 Wade Ave., Modesto, CA 95351 <br /> Tasnim Akhtar, 1514 E. Market St., Stockton, CA 95205 <br /> Vapor Intrusion Evaluation Comment Letter 0110 <br />