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PUBLIC hEALTH SERVICES <br /> 6 . <br /> S <br /> SAN JOAQUIN COUNTY <br /> ENVIRONMENTAL HEALTH DIVISION <br /> Karen Furst, M.D., M.P.H., Health Officer <br /> 304 East Weber Avenue, Third Floor • Stockton, CA 95202 oR ' <br /> 209/468-3420 COPY <br /> RAYMOND FARMER NOV 131997 <br /> 3810 FOURTEEN MILE DRIVE <br /> STOCKTON CA 95219-3809 <br /> Re: Former Toyota Town Site Code: 1151 <br /> 610 North Hunter Street <br /> Stockton CA 95202 <br /> San Joaquin County Public Health Services, Environmental Health Division (PHS/EHD) has <br /> completed review of the "Summary Report' dated September 17, 1997 which was prepared <br /> by Smith Environmental Technologies. PHS/EHD has the following comments for your <br /> consideration and response. <br /> The report presented the results obtained during the June 30 - July 3, 1997 investigation to <br /> determine the extent of groundwater and soil contamination. Seven soil borings were drilled <br /> and sampled, three of which were converted into monitoring wells, MWl - MW3 , and two of <br /> which were converted into vapor extraction wells, VWl and VW2. The investigation <br /> encompassed contamination associated with former petroleum fuel tanks and a waste oil tank. <br /> Soil contamination was detected in each soil boring with the highest concentrations detected <br /> in VWI /SB3 at 20. 5 feet below ground surface (bgs) with 39 ppm TPH-diesel, 7,800 ppm <br /> TPH-gas, 35 ppm benzene, 680 ppm toluene, 210 ppm ethylbenzene, and 1 ,200 ppm xylene. <br /> Additionally, 52 ppm lead and 110 ppm TPH-motor oil were detected at 15 . 5 feet bgs from the <br /> same boring, The maximum depth that was investigated was 45 feet bgs and contamination <br /> was noted albeit at lower concentrations. Additional investigation to determine the full vertical <br /> extent of the soil contamination will be required. <br /> Significant groundwater contamination was detected up to 130,000 ppb TPH-gas and 11 ,000 <br /> ppb benzene. The extent of the groundwater contamination plume is unknown. Additional <br /> I <br /> nvestigation to determine the full lateral and vertical extent of the groundwater contamination <br /> II will be required. <br /> The analytical results suggested that the site may be contaminated by the oxygenate MTBE as <br /> evidenced in the sample collected from S137 at 28. 5 feet bgs. However, the EPA Method 8260 <br /> results were not able to confirm or negate these results because MTBE was not included within <br /> the suite of analytes run. Additionally, the detection limits were so elevated (up to 2,500 times) <br /> that the results lacked relevance. <br /> The report included recommendations to install four additional monitoring wells to define the <br /> lateral extent of the groundwater contamination. The report also recommended the <br /> installation of an air sparge well to perform feasibility analysis. PHS/EHD concurs with these <br /> recommendation and a work plan should be submitted by December 3, 1997. <br /> A Division of San Joaquin County Health Care Services <br />