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FILE COPY <br /> ENVIRONMENTAL HEALTH DEPARTMENT <br /> PpU1N SAN JOAQUIN COUNTY <br /> UN%r SNp erVlSOIS <br /> Donna K.Heran,RE.x.S. 304 East Weber Avenue, Third Floor Carl Borgman,R.E.H.S. <br /> < Director Mike Huggins,R.E.H.S.,R.D.I. <br /> Al Olsen,R.E.H.S. Stockton, California 95202-2708 Douglas W.Wilson,R.E.H.S. <br /> • �, 'PProgram Manage Telephone: (209) 468-3420 Margaret Lagorio,R.E.H.S. <br /> 4(i F 6, 4\ R. .xsRobert McClellan,R.E.H.S. <br /> Laurie n � ' Fax: (209) 464-0138 <br /> Program <br /> raamm Manager Mark Barcellos,R.E.H.S. <br /> JERRY CASTRO JAN 3 0 2003 <br /> PACIFIC CAR WASH <br /> 4405 PACIFIC AVE <br /> STOCKTON CA 95207 <br /> Re: Pacific Car Wash Site Code: 1215 <br /> 4405 Pacific Ave. RO#: 00392 <br /> Stockton, CA. 95207 CUM 012215 <br /> San Joaquin County Environmental Health Department (EHD) has reviewed Advanced <br /> GeoEnvironmental's (AGE) December 18, 2002 correspondence regarding the meeting <br /> held on December 17, 2002 at AGE's office. On January 9, 2003, EHD met with Central <br /> Valley Regional Water Quality Control Board (CVRWQCB) staff to discuss AGE's choice <br /> for interim remedial action. <br /> Although conclusions were reached in the AGE meeting held on December 17, slightly <br /> different concerns were considered at the CVRWQCB meeting. After evaluating site- <br /> specific conditions, CVRWQCB staff questioned AGE's conclusion that groundwater <br /> extraction (GWE)would be the most effective interim action for mitigating the offsite <br /> petroleum plume migration. CVRWQCB staff requested that additional supporting <br /> evidence and arguments be submitted to support this conclusion. Groundwater pumping <br /> test data should be included to support its use as an effective migration control. The <br /> CVRWQCB has advised that pumping tests should provide for flow rates that start low <br /> and progressively increase to higher gallons per minute (gpm) rates. Historically, <br /> premature drying of wells due to low recharge rates of less permeable hydrological units <br /> have disrupted tests, skewed results, and have led to system design problems later on <br /> during full remediation. <br /> The CVRWQCB felt that control of the offsite groundwater petroleum impact would be <br /> better effected if In-situ Air Sparging (IAS) in combination with soil vapor extraction <br /> (SVE)were utilized as an interim remedial action at the 'core' of the groundwater plume. <br /> EHD is aware of the current GWE interim remedial action at a nearby site and that the <br /> initial data indicate that that interim remedial action is yielding good results. However, <br /> the CVRWQCB felt that the extremely high dissolved TPHg concentrations on the <br /> subject site (100,000 µg/I in the 'core' of the plume onsite with nearly the same <br /> concentration approximately 300 feet down gradient) may indicate that a large mass of <br /> hydrocarbon-impacted soil is continuing to leach into the groundwater. It was the <br /> recommendation of the CVRWQCB that IAS-SVE in the `core' area be the interim <br /> remedial action of choice and may be a more prudent expenditure of funds and effort. <br /> EHD requests that you have your consultant compare IAS/SVE and GWE as interim <br /> remediation techniques utilizing as much site-specific data as is available and <br /> professional judgment to select the more appropriate method and then submit a work <br /> plan to effectuate the preferred interim remedial system to EHD within 45 days for <br /> evaluation. <br />