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San Joaquin County DIRECTOR <br /> PQ N Donna Heran,REHS <br /> �O CSG Environmental Health Department ASSISTANT DIRECTOR <br /> 600 East Main Street Laurie Cotulla,REHS <br /> { Stockton, California 95202-3029 PROGRAM COORDINATORS <br /> •' Carl Borgman,REHS <br /> Cq'•..� �P Website: www.s ov.or /ehd Mike Huggins, REHS, RDI <br /> J9 9 Margaret Lagorio,REHS <br /> Phone: (209)468-3420 Robert McClellon, REHS <br /> Fax: (209)464-0138 Jeff Carruesco, REHS,RDI <br /> 07 March 2008 Kasey Foley,REHS <br /> Mr. Stephen Valentine <br /> Steve & Genes Service <br /> 6232 Hemet Avenue <br /> Stockton, CA 95207 <br /> Subject: Steve & Genes Service <br /> 2315 N. EI Dorado St. <br /> Stockton, CA 95204 <br /> The San Joaquin County Environmental Health Department (EHD) has received and <br /> reviewed Additional Site Characterization Work Plan (WP), dated 10 December 2007, <br /> prepared by Geological Technics, Inc. (GTI), your consultant for this site. The EHD has <br /> also reviewed the data collected to date for your site and some data for the Shell Oil <br /> Company (Shell) site toward the east at 2320 N. EI Dorado Street, to evaluate the WP. <br /> The WP was prepared to address EHD directives conveyed by EHD letter dated <br /> 12 October 2007. <br /> In the cover letter for WP, GTI recommends delaying performance of a soil gas survey to <br /> evaluate potential vapor intrusion from impacted onsite soil into the nearby residences <br /> until the current soil vapor extraction (SVE) operation has reached an asymptotic state. <br /> GTI has estimated the radius of influence of the vapor extraction wells at 45 feet; the <br /> EHD believes this distance is the result of a laterally continuous sand unit in the vadose <br /> zone at approximately 20 feet below surface grade (bsg). The adjacent Castle Street <br /> residence is approximately 75 feet from vapor extraction well VEW-1 and the adjacent <br /> North Eldorado Street residence is approximately 55 feet from VEW-2. The Central <br /> Valley Regional Water Quality Control Board (CVRWQCB) has identified vapor intrusion <br /> into structures in close proximity to unauthorized releases from underground storage <br /> tank (UST) sites to be a potential health concern that should be evaluated and <br /> addressed if appropriate. As the adjacent residences are currently occupied, it is <br /> necessary to evaluate the potential for vapor intrusion into these structures at this time. If <br /> a significant potential exists, it may be appropriate to expand the current SVE system or <br /> take some other corrective action to mitigate this hazard; therefore the potential for soil <br /> vapor intrusion into these structures should be promptly evaluated and not delayed for <br /> the SVE remediation to be concluded. Please note that the evaluation may or may not <br /> require collection of soil gas samples depending on site characteristics and site data. <br /> In WP, GTI proposes to advance one soil boring (SB-5) between previous soil boring <br /> SB-B and monitoring well MW-2 to a depth of 100 feet below surface grade (bsg) to <br /> collect soil samples for laboratory analysis between 90 and 100 feet bsg. The purpose <br /> for this data is to delineate the vertical extent of impacted soil in the presumed <br /> contaminant source area. GTI also proposes to advance four soil borings off-site to 100 <br /> WP Comment Letter(l ns <br />