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� v <br /> 1 <br /> AS SOCIATES INC <br /> 20 feet bgs and 26 5 to 30 feet bgs consisted of clayey sand and lean clay with sand Soil in <br /> boring MW 1 from depths between 26 5 to 30 feet bgs and 36 to 40 feet bgs consisted of well <br /> ' graded sand Soil in boring MW1 from depths between 36 to 40 feet bgs and 41 feet bgs, the <br /> maximum depth explored, consisted of lean clay <br /> Soil in borings MW2 and MW3 from depths between 16 5 to 20 feet bgs and 21 5 to 25 feet bgs <br /> consisted of elastic silt with sand Soil in borings MW2 and MW3 from depths between 21 5 to <br /> 25 feet bgs and 36 5 to 38 feet bgs consisted of well graded sand and silty sand Lean clay with <br /> 1 sand was present in boring MW2 between 26 feet and 26 5 to 30 feet bgs Soil in borings MW2 <br /> and MW3 from depths between 36 5 to 38 feet bgs and 39 feet bgs, the maximum depth <br /> 1 explored, consisted of lean clay <br /> 3.2 Hydrogeolo <br /> 1 Water level measurements were collected from wells MW1 through MW3 on February 19, 1999 <br /> Water levels ranged from 21 88 to 22 47 feet below the tops of the well casing elevations The <br /> 1 water level data were used to develop the groundwater elevation contour map (Figure 3) <br /> Assuming that horizontal isotropic conditions prevail, groundwater in the uppermost aquifer <br /> beneath the site flowed towards the north-northeast The average hydraulic gradient on February <br /> 19, 1999 was calculated to be 0 0003 ft/ft or approximately 16 ft/mile A summary of <br /> groundwater monitoring data is presented in Table 2 <br /> ' 4.0 ANALYTICAL RESULTS <br /> ' 4,1 Soil Analytical Results <br /> Soil samples collected from borings MW1 and MW3 contained very low concentrations of TPHg <br /> ' (13 and 3 9 part per million (ppm)) Soil samples collected from borings MW1 and MW3 also <br /> contained detectable concentrations of BTEX Soil samples collected from borings MW1 and <br /> MW3 did not contain detectable concentrations of oxygenate fuel additives Soil samples <br /> 1 collected from boring MW2 contained no detectable concentrations of TPHg, BTEX, or <br /> oxygenate fuel additives Analytical results of soil samples are summarized in Table 1 <br /> ' 4.2 Groundwater Anal tical Results <br /> The groundwater sample collected from well MW 1 contained detectable concentrations of TPHg, <br /> benzene, ethylbenzene, and xylenes TPHg concentration was 4,700 parts per billion (ppb), and <br /> the chromatogram pattern indicated a weathered gasoline result The benzene, ethylbenzene, and <br /> xylenes concentrations ranged from 13 to 99 ppb Only benzene exceeded the California <br /> ' Maximum Contaminant Level (MCL) for drinking water The groundwater sample from well <br /> MW1 did not contain detectable concentrations of oxygenate fuel additives <br /> Is <br /> w 1149811reportslsumwel doc 4 <br />