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a <br /> PUBLIC H15ALTH SERVICES �o <br /> SAN JOAQUIN COUNTY <br /> ENVIRONMENTAL HEALTH DIVISION <br /> Karen Furst, M.D., M.P.H., Health Officer �q, A . <br /> 304 East Weber Avenue, Third Floor * Stockton, CA 95202 Foy <br /> 2091468-3420 FILE C <br /> BP OIL COMPANY <br /> SCOTT HOOTON APR 2 g 1999 <br /> 295 SW 41 ST, BLVD 13 , STE N <br /> RENTON WA 98055 <br /> Re: BP Oil #11193 Site Code: 1129 <br /> 3202 W. Hammer Ln. <br /> Stockton., CA 952091 <br /> San Joaquin County Public Health Services Environmental Health Division (PHS/EHD) <br /> has reviewed the Underground Storage Tank and Product Piping Removal Report dated <br /> April 12, 1999 prepared by Gettler-Ryan Inc. for the above referenced site. Analytical <br /> results from soil and water samples collected beneath the Underground Storage Tanks <br /> (USTs), product lines and dispensers evidenced contamination. <br /> Overexcavation of contaminated soil beneath the dispenser and piping area and <br /> contaminated soil removed from the UST excavation resulted in the generation of <br /> approximately 690 cubic yards of contaminated soil. This soil was removed off site to <br /> Forward Inc. disposal facility. Contaminated soil was observed remaining in the UST <br /> excavation after removal of the original USTs. New USTs were then installed on top of <br /> the contaminated soil in the same excavation. Clean fill was placed on and around the <br /> new USTs and subsequently the surface was paved over in this area. The amount of <br /> contaminated soil left in place at this site has not been determined. <br /> Contamination of the groundwater has been evidenced continuously since 1992 by <br /> analytical results of the water collected quarterly from the Monitoring Wells (MWs) at <br /> the site. MW 1 was destroyed under permit in order to allow placement of the new USTs. <br /> This MW was the most distantly located MW downgradient from the source of the <br /> contamination. MW 1 had evidenced increasing concentrations of Total Petroleum <br /> Hydrocarbon as gas and Methyl tertiary Butyl Ether in groundwater prior to its <br /> destruction. The contaminant plume has not been defined laterally or vertically in the <br /> soil or groundwater. The potential for offsite migration of contamination is significant. <br /> In addition, groundwater has risen over the tops of all of the screened intervals of the <br /> existing MWs at this site. Since water is above the well screens the data in Quarterly <br /> Monitoring Reports may not be representative of groundwater conditions. Appropriately <br /> screened MWs should be installed to show the lateral and vertical extent of groundwater <br /> contamination. Well screen intervals should be limited to 20 feet in length. It may be <br /> necessary to install wells screened in differing intervals. <br /> A lDivision of San Joaquin County Health Care Services <br />