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San Joaquin County DIRECTOR <br /> Environmental Health Department Donna Hera <br /> p ASSISTANT DIRECTOR <br /> 600 East Main Street Laurie Cotulla, REHS <br /> N { ` Stockton, California 95202-3029 <br /> PROGRAM COORDINATORS <br /> Mike Huggins, REHS, RDI <br /> c9<iFo"a��P Website: www.sjgov.org/ehd Margaret Lagorio,REHS <br /> Robert McClellon, REHS <br /> Phone: (209) 468-3420 Jeff Carruesco,REHS, RDI <br /> Fax: (209) 464-0138 Kasey Foley, REHS <br /> July 17, 2009 <br /> `} 6C 1-L4-c° <br /> Mr. James M. Langston <br /> 15820 S. Harlan Rd. #33 <br /> Lathrop, CA 95330 <br /> Subject: Langston's Arco (former) RO#: 0316 <br /> 15615 S. Seventh St. APN: 196-250-52 <br /> Lathrop, CA 95330 SWRCB-CUF#:0367 <br /> The San Joaquin County Environmental Health Department (EHD) has reviewed Feasibility <br /> Study Report (FS) dated June 29, 2009 and received on Geotracker July 6, 2009. The FS was <br /> required by the EHD by correspondence dated April 29, 2009. <br /> The FS discussed three remedial alternatives, ground water extraction treatment and disposal, " <br /> enhanced bioremediation using pure oxygen injection, and in-situ chemical oxidation (ISCO) <br /> using RegenOx. Based on application, monitoring, and costs, your consultant, Advanced <br /> GeoEnvironmental concluded that oxygen injection would be the most feasible and cost- <br /> effective. <br /> It has not been shown that the addition of oxygen to the subsurface would effectively enhance <br /> bioremediation. If the subsurface is oxygen deficient, the addition of oxygen may be beneficial, <br /> but it has not been shown that a deficiency exists. In addition, the FS did not include data to <br /> support that adequate biological or nutritional sources exist in the subsurface or are available to <br /> support insitu bioremediation. It is not known if biotoxins are present that could hamper or <br /> destroy the anticipated bio-remediation that the injected oxygen could provide. <br /> The FS is inadequate and not approved as submitted. A revision that addresses these <br /> concerns is needed for EHD approval. <br /> The Central Valley Regional Water Quality Control Board (CVRWQCB) requires that a bench <br /> scale test (BST) to evaluate for waste discharge requirements (WDRs) prior to the EHD <br /> approving the injection of oxygen into the subsurface. Oxygen injection could cause minerals <br /> and metals naturally occurring in the subsurface to oxidize and produce byproducts that could <br /> further degrade the water quality beneath this site, The BST is needed to demonstrate the <br /> efficacy of the method and a lack of byproducts that will degrade water quality or pose a hazard <br /> to human health. <br /> A BST is to be conducted after the EHD approves the revised FS. You will be advised when a <br /> work plan to collect the soil samples needed to conduct the study is to be submitted. <br />