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' Stockton Taxi Cab/Sunland Gasoline Sep tember 16,2003 <br /> 2085 Fremont Street,Stockton, California Page 8 <br /> I Report of Findings: Lateral and Vertical Extent <br /> of Soil and Groundwater Contamination <br /> 6.1 Local Hydrology <br /> Groundwater was encountered at approximately fifty-seven feet (57') below <br /> ' ground level. <br /> ' 7.0 Conclusions <br /> Based on the results presented in this report, VHF, Inc. believes that the soil and <br /> ' groundwater underlying this site has been significantly impacted by petroleum <br /> hydrocarbons. The source of the soil contamination seems to be in the vicinity of the <br /> former underground fuel storage tanks and near boring B-2. Lithologic and <br /> contamination cross-sections are found in Figures 4a and 4b of this report. This <br /> conclusion is based on the previous borings conducted on site in February, 2000 and the <br /> results of this investigation as follows: <br /> - Groundwater was encountered at approximately fifty-seven feet (57') below ground <br /> ' level. <br /> MW-1 was completed approximately thirty feet(30') east of the former USTs. MW- <br /> 1 showed significant soil contamination beginning at twenty-five feet (25')below <br /> '! ground level and increasing with depth to sixty feet (60')below ground level. The <br /> largest levels of contamination were found at sixty feet (60'), at the soil-groundwater <br />' interface. The contamination levels drop off below the soil-groundwater interface. <br /> - MW-4, located at the southeast corner of the former UST location, showed significant <br /> levels of contamination to a depth of 100 feet. <br /> Boring B-5 located approximately thirty-five feet (35') to the south of the former <br />' USTs showed significant levels of contamination increasing with depth to fifty feet <br /> (50') below ground level. At the soil-groundwater interface, at a depth of <br /> approximately sixty feet(60'), the soil sample was free of contamination. Soil <br /> contamination was again present at a depth of seventy feet(70'). <br /> - MW-2 was completed on the northwest corner of the former UST location. MW-2 <br /> was free from contamination at all depths except for the forty foot sample. <br /> Significant soil contamination was present at only the forty feet (40') below ground <br />' level. <br /> Based on the above facts, it seems likely that the general groundwater flow direction <br />' is to the southeast because MW-2 did not show the presence of contamination at the <br /> soil-groundwater interface while MW-1 and MW-4 exhibited significant levels of <br /> . contamination at that depth. The site-specific groundwater flow direction will be <br />' determined during the first quarterly monitoring event. <br />