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I 1 <br /> ENVIRONMENTAL HEALTH DEPARTMENT <br /> SAN JOAQUIN COUNTY <br /> •` o��R coG Unit Supervisors <br /> i � ti 2 Donna K Heran,R E H S <br /> ` 304 East Weber Avenue, Third Floor Carl Borgman,R E H s <br /> ' Director <br />' alifornia 95202-2708 Mike Huggins,R E H S,R D i <br /> AlAi Olsen,R E H S �tOGICtOn, Douglas W Wilson,R E ii S <br /> • c +.. P• Program Manager Telephone (209) 468-3420 Margaret Lagono,R E H S <br /> FOR`' Laurie A Cotuila,R E H S Robert McClellon,R E H S <br /> Program Manager FaX (209) 464-0138 Mark Bareellos,R E H S <br /> I <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 1216 <br />' 4405 Pacific Ave RO# 00392 <br /> Stockton, CA 96207 CUF# 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 remediatron <br /> ` The CVRWQCB Telt that control of the offsite groundwater petrolea�i impact weLic+ he <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 /> 1 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 µg11 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 ti <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 IASISVE 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 />