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-� SEI;(VICES <br /> �9R+4 .co <br /> PUBLI � <br /> SAN JOAQUIN COUNTY Ur <br /> ENVIRONMENTAL HEALTH DIVISION <br /> Karen Furst, M. <br /> D. M.P.H. Health Officerig0 <br /> 304 East Weber Avenue,Third Floor • Stockton, CA 95202 <br /> 2091468-3420 <br /> SEP 0 42001 <br /> LORI SHIELDS <br /> DIESEL PERFORMANCE <br /> 2804 EAST FREMONT STREET <br /> STOCKTON CA 95205 <br /> RE: Diesel Performance SITE CODE: 1120 <br /> 2804 E. Fremont Street <br /> Stockton CA 95205 <br /> San Joaquin County Public Health Services, Environmental Health Division (PHS/EHD) <br /> has reviewed the Work Plan for Soil Vapor Extraction and Additional Investigation dated <br /> August 14, 2001 that was submitted on your behalf by ATC Associates Inc. and has the <br /> following comments. <br /> The work plan proposes the advancement of one cone penetrometer test (CPT) boring <br /> in the area of a former underground storage tank (UST), the installation of two additional <br /> shallow groundwater monitoring wells, the installation of three soil vapor extraction <br /> (SVE) wells, and the performance of a SVE pilot test. <br /> The CPT boring will be completed to investigate the vertical extent of the petroleum <br /> hydrocarbon contamination in the source area. The work plan states that the boring will <br /> extend until a significant clay layer is encountered, and that one grab groundwater <br /> sample will be collected from a sand layer which presumably would underlie the clay <br /> layer. The estimated depth of the boring is 100 feet below surface grade (bsg), but it will <br /> be extended if necessary, and if site conditions allow it, to find a deeper water-bearing <br /> zone. Analysis of groundwater samples collected from monitoring well MW-3, which is <br /> located in the source area and has a screen interval from 45-65 feet bsg, have shown <br /> significant amounts of petroleum hydrocarbon contamination. The vertical extent of this <br /> contamination must be defined. PHSIEHD directs that grab groundwater samples be <br /> collected from depths of 80-feet bsg and below, whether a significant clay layer is <br /> discovered or not. <br /> Two additional monitoring wells will be installed to first encountered groundwater for <br /> lateral assessment of the shallow contaminant plume. PHSIEHD directs that in addition <br /> to the two proposed wells, a third well be installed directly south of MW-2, for more <br /> complete lateral definition of the shallow contaminant plume. <br /> PHSIEHS approves the proposed locations of three SVE wells, and the proposed SVE <br /> pilot test procedure. Soil analytical data collected from previous investigations at the site <br /> indicate a core of petroleum hydrocarbon contaminated soil exists in the source area to <br /> approximately 50 feet bsg. This area will be the target of the SVE pilot test. <br /> A Division oESan Joaquin County Health Cate Services <br />