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�� ��X15 u i ry <br /> LALTH SERV oPUBLIC H <br /> SAN JOAQUIN COUNTY :< <br /> ENVIRONMENTAL HEALTH DIVISION <br /> Karen Furst, M.D., M.P.H., Health O QLi-ii60 <br /> 304 East Weber Avenue, Third Floor • Stockton, CA 95202 <br /> 2091465-3420 T11 <br /> BP OIL COMPANY JUL 13 1999 <br /> SCOTT HOOTON <br /> 295 SW 41 ST, BLVD 13 , STE N <br /> RENTON WA 98055 <br /> Re: BP Oil # 1119 <br /> Site Code: 1129 <br /> 3202 W. Hammer Ln. <br /> Stockton, CA 95209 <br /> San Joaquin County Public Health Services Environmental Health Division (PHS/EHD) <br /> has reviewed the investigation Work Pian (IWP) dated June 29, 1999 prepared by <br /> Cambria Environmental Technology, Inc. The IWP does not propose sufficient <br /> investigative work to determine the lateral and vertical extent of contamination at the site <br /> as was directed in the PHS/EHD letter dated April 28, 1999 and is not approved. <br /> A Work Plan that investigates the vertical and lateral extent of the contamination, as <br /> stated in the PHS/EHD April 1999 letter must be submitted. The Work Plan should <br /> contain all information discussed in the Central Valley Regional Water Quality Control <br /> Board (RWQCB) Tri-Regional Board Recommendations, Appendix A. Ground Water <br /> Investigation, Page A-5(copy enclosed). <br /> Soil contamination has been documented as shallow as 4 feet below surface grade (bsg) <br /> in the dispenser area and as deep as 21 feet bsg in MW2. MTBE was detected in all the <br /> soil samples collected beneath the Underground Storage Tanks (USTs) at 15 feet bsg. <br /> Installing two monitoring wells (MWs) drilled to a depth of 20 feet bsg will not define <br /> the vertical or lateral extent of the contamination at this site <br /> Soil samples must be collected and analyzed below 20 feet from the surface grade in the <br /> area of the UST system. Investigation must continue until field observations and <br /> screening equipment indicate the contamination has been defined vertically. Once the <br /> contamination is defined vertically in the UST system area, lateral definition can be <br /> evaluated. <br /> PHS/EHD recommends the Cone Penetrometry Test (CPT) boring method to obtain the <br /> vertical extent of contamination. The CPT method will generate relevant lithological and <br /> hydrological data for this site. This data should be obtained prior to the placement of <br /> additional MWs. In addition, the well survey requested in the April 1999 PHS/EHD <br /> letter should be conducted prior to further MW placement. <br /> A Division of San 1oaquin County Health Care Services <br />