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'y <br /> San Joaquin County <br /> PIC). .� Environmental Health Department DIRECTOR <br /> �• —,E1 � Donna Heran, RENS <br /> 600 East Main Street <br /> a' PROGRAM COORDINATORS <br /> Stockton, California 95202-3029 Robert McClellon, REHS <br /> I J <br /> ,• ' Jeff Carruesco, REHS,RDI <br /> meqF o R.. Website: www.sjgov.org/ehd Kasey Foley,REHS <br /> �! Linda Turkatte, REHS <br /> Phone: (209) 468-3420 <br /> Fax: (209) 464-0135 <br /> July 5, 2011 <br /> Messrs. Kirk Larson, PG, and Robert Trommer, CHG <br /> State Water Resources Control Board <br /> Division of Financial Assistance <br /> 1001 1 Street <br /> Sacramento CA 95814 CUF Claim No. 13455 <br /> Subject: 6732 Highway 88 E, Stockton, CA <br /> Annual Five-Year Review Update Recommendations May 2011 <br /> San Joaquin County Environmental Health Department (EHD) has received and reviewed the <br /> annual five-year review update letter dated 05 May 2011 from Kirk Larson of the State Water <br /> Quality Control Board (SWQCB) Cleanup Fund (CUF) for the above-referenced site. The CUF <br /> recommends that the EHD consider the site for closure. <br /> In the opinion of the EHD, this site should remain in active soil vapor extraction (SVE) <br /> remediation mode until the SVE system has reached its limit of cost-effectiveness. Most of the <br /> contamination at this site is at shallow depth in the vadose zone currently being addressed by <br /> the SVE system. It was estimated that 4,416 pounds of contaminants were sorbed to vadose <br /> zone soil prior to the initiation of SVE. According to the last report received on GeoTracker, <br /> during the three-month period between 2 December 2010 and 3 March 2011, the soil vapor <br /> extraction (SVE) system removed 331 pounds of total petroleum hydrocarbons and a total mass <br /> of 2,063 pounds of TPH has been removed since the system was put on line in May 2010. <br /> These data indicate to the EHD that the SVE system was still performing effectively as of the <br /> last report. <br /> The impact to groundwater appears to have been minimal; MW-1 has been moderately <br /> impacted when not dry, MW-2 and MW-3 had had low to no impact. The tops of the screens in <br /> monitoring wells MW-4 and MW-5 are nearly 40 feet below the water table and have not been <br /> significantly impacted. No monitoring well is or has been intensely impacted, indicating that the <br /> hydrocarbon mass in the vadose zone has not migrated to the saturated zone. Implementation <br /> of SVE appears to have been timely and effective and is reducing the potential for the vadose <br /> zone contaminant mass to impact groundwater. <br /> As long as hydrocarbon recovery rates are significant, the EHD recommends that the CUF <br /> withhold the closure consideration recommendation and instead recommend continued <br /> remediation by SVE until the limit of cost-effectiveness of the system has been achieved <br /> thereby providing the maximum protection to groundwater for the unmonitored future. The EHD <br /> also anticipates that the economic limit of the SVE system will be achieved soon and will push <br /> the site closure process at that time. <br /> Annual 5-Year Review Update Response 2011.doc <br />