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X ,a <br /> STATE OF CAUFORNIA <br /> GEORGE DEUKMEJIAN Governor <br /> CALIFORNIA REGIONAL WATER QUALITY CONTROL BOARD— <br /> CENTRAL VALLEY REGION <br /> 3443 ROUTIER ROAD <br /> SACRAMENTO,CA 96827-3098 - <br /> M1.j <br /> 3 October 1989 QCT r� 198 <br /> A1T <br /> Ms. Diane Hinson <br /> Registered Environmental Health Specialist <br /> Environmental Health Division <br /> San Joaquin County Department of Public Health Services <br /> P.Q. Box 2009 <br /> Stockton CA 95201 <br /> BILL'S BAIT & BEACON GAS, 515 WEST ELEVENTH STREET, TRACY, PHASE II <br /> GROUND WATER ASSESSMENT PROPOSAL & PHASE III REMEDIAL ACTION PLAN <br /> We have reviewed the 17 October 1988 "Phase II Ground Water Assessment <br /> Proposal " and the 30 June 1989 "Phase III Remedial Action Plan" for <br /> this site; both prepared by Geological Technics. The Phase II proposal <br /> includes the installation and sampling of three additional ground water <br /> monitoring wells to determine the extent of ground water contamination. <br /> The Phase III proposal includes excavation and on-site treatment of <br /> contaminated soil , and extraction and on-site treatment of up to 10,000 <br /> gallons of ground water from the excavation. <br /> We recommend resampling the existing wells prior to developing a work <br /> plan for the next phase of ground water investigation. In general , we <br /> do not believe it is appropriate to base recommendations for additional <br /> work on the results from one round of samples. Resampling is necessary <br /> to verify the results from the initial round of sampling, and to provide <br /> a statistical basis for designing the next phase of investigation. <br /> We agree that the upper 10 feet of the saturated zone should be <br /> investigated as a single hydrogeologic unit. However, the proposed well <br /> construction (0.04 inch well screen and medium aquarium sand filter <br /> pack) may not be an appropriate well design for this hydrogeologic unit. <br /> If the proposed well design does not produce adequate ground water <br /> samples, the operator will be required to replace the wells with ones of <br /> appropriate design. In addition, the bentonite grout seal should not be <br /> placed directly on the sand filter pack, but rather should be placed <br /> above an appropriate seal which will prevent intrusion of grout into the <br /> filter pack. <br /> We have no objection to the proposal to extract ground water from the <br /> excavation. However, it is not clear whether the consultant intends to <br /> discharge the treated water to the sanitary sewer or to the storm sewer. <br /> If the water is discharged to the sanitary sewer, permits must be <br />