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ENVIRONMENTAL HEALTH DEPARTMENT
<br /> a�U'N SAN JOAQUIN COUNTY
<br /> Donna K.Heran,R.E.H.S. Unit Supervisors
<br /> 304 East Weber Avenue, Third Floor Carl Borgman, R.E.H.S.
<br /> l ' 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 /> c ��c Program Manager Laurie A.Cotulla,RE.H.S.
<br /> F-6 Telephone: (209) 468-3420 Margaret Lagorio,R.E.H.S,
<br /> q a
<br /> Program Manager Fax: (209) 464-0138 Robert McClellon,R.E.H.S.
<br /> Mark Barcellos,R.E.H.S.
<br /> DANIEL SILVA SEP 0 4 2003
<br /> WEST CLAY PROPERTIES
<br /> PO BOX 6152 R-RCEIV 1
<br /> STOCKTON CA 95206 Q 8 s ,3
<br /> RE: West Clay Properties Site Code: 1065
<br /> 639 West Clay Street
<br /> Stockton,CA 95206
<br /> San Joaquin County Environmental Health Department(EHD)has received and reviewed Ground WaterF—ctraction
<br /> Feasibility Test Report(the report),dated May 14,2003,prepared by_Advanced GeoEnvironmental,Inc. (.AGE). The
<br /> report summarized the results of an 8-hour groundwater extraction feasibility test conducted using extraction well
<br /> EW-2 in the area of the former underground storage tanks(UST) to the south(Former UST No.3 area)on July 19,
<br /> 2001. At pumping rate of 4 gallons per minute (gpm),AGE calculated a radius of influence of 80 feet,
<br /> transmissiviry of 230 square feet per day,and storativity value of 0.007. AGE recommended installing a
<br /> groundwater extraction system as interim remediation to begin removing the dissolved petroleum hydrocarbon in
<br /> groundwater. The extracted groundwater will be treated with granular activated carbon(GAC) before discharge to
<br /> City of Stockton sanitary sewer system.
<br /> It appears that hydrocarbon concentrations in water recovered from EW-2 increase during continuous pumping,
<br /> such as during the July 2001 pumping test,compared to routine purging and sampling. Before approving the
<br /> interim remediation,EHD recommends that another extended pumping test be conducted to be sure that sufficient
<br /> hvdrocarbon mass will be recovered to justify a pump and treat system. Also,please have your consultant provide
<br /> EHD with estimates of the hydrocarbon mass that will be addressed and the mass that may be recovered. If your
<br /> consultant believes that pump and treat is justified,submit a work plan with design specifications and installation
<br /> instructions for the groundwater extraction system to EHD by September 30,2003. EHD recommends installing
<br /> transducers in MW-4,2MW-5,MW-6x1,and%lW-6B to monitor the effect of the groundwater extraction system
<br /> during the first week of operation on the northern dissolved hydrocarbon plume.
<br /> EHD recommends performing interim soil remediation,possibly by over-excavation,in the area of the former UST
<br /> cluster to the north. Significant level of contaminants have been reported in the soil: 7,000 micrograms per .
<br /> kilograms of Total Petroleum Hydrocarbons as gasoline(ITH-g)in the 19-foot below surface grade (bsg) soil
<br /> sample of boring B-9,4,400 mg/kg of TPH-g in the 20-foot bsg soil sample of EW-1,and 13,000 mg/kg of Total
<br /> Petroleum Hydrocarbons as diesel(TPH-d) in the 20-foot bsg soil sample from EW-1. Current groundwater depth
<br /> at the site is at approximately 18 feet bsg(March 2003). If left in place,the contamination in the soil is likely be a
<br /> continuously releasing source to groundwater. Submit a work plan for soil interim remediation to EHD by.
<br /> September 30,2003.
<br /> Donna Heran,RENS,Director /
<br /> Environmen al Health Division
<br /> effrey Wong, Senior REHS Nuel C.Henderson,Jr.,RG j
<br /> LOP/Site Mitigation Unit IV LOP/Site;<Iitigation Unit IV
<br /> C: RWQCB,Central Valley Region—James L.L.Barton,RG
<br /> C: vkdvanced GeoEnvironmental,Inc.—Paul Dotsun
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