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:A <br /> A S S O C I A T E S I N C <br /> The groundwater samples from well MW I, MM2, MW3, and MM4 were analyzed by Sequoia for <br /> TPHg, TPHd, TPHk, BTEX, and oxygenate fuel additives Groundwater analytical results are <br /> ' summarized in Table 3, and laboratory data sheets are presented in Appendix C <br /> 3.0 SUBSURFACE CONDITIONS <br /> ' 3,^1 Geolozy <br /> ' The upper 6 5 to 10 feet of soil encountered in soil borings MW2, MW3, and. MW4 generally <br /> consisted of lean clay Poorly graded sand and silty sand was present between 6 5 to 10 feet bgs <br /> and 26 5 to 35 feet bgs Soil from depths between 26 5 to 35 feet bgs and 41 5 to 50 feet bgs <br /> ' consisted of lean clay and elastic silt Soil from depths between 41 5 to 50 feet bgs and 66 5 feet <br /> bgs, the maximum depth explored, consisted of poorly graded sand with varying amounts of silt <br /> ' 3_2 H ydrop-eolop-y <br /> ' Water level measurements were collected from wells MW 1 through MW4, on December 22, <br /> 1999 Water levels ranged from 48 45 to 48 78 feet below the tops of the well casing elevations <br /> The 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 southwest The average hydraulic gradient on December 22, <br /> 1999 was calculated to be 0 002 ft/ft or approximately 11 ft/mile A summary of groundwater <br /> ' monitoring data is presented in Table 2 <br /> 4.0 ANALYTICAL RESULTS <br /> 441 Soil Analytical Results <br /> ' Petroleum hydrocarbon constituents were detected only in the soil samples collected from boring <br /> MW2 at depths of 40 5 and 50 5 feet bgs TPHd, TPHg, TPHk, ethyl benzene and xylenes were <br /> present at low to moderate levels The highest reported constituent concentrations in this boring <br /> ' were observed in the shallower soil sample collected at 40 5 feet bgs The petroleum <br /> hydrocarbons appear to attenuate rapidly with depth as indicated by a reduction in concentrations <br /> of petroleum hydrocarbons to nondetectable or near nondetectable levels in the soil sample <br /> collected at 50 5 feet bgs No hydrocarbon analytes were reported in PwqD1&the sample collected <br /> from the bottom of the boring at 65 5 feet bgs or from any of the samples collected from bonngs <br /> ' MW3 or MW4 <br /> No oxygenate fuel additives were detected above laboratory method detection limits in any soil <br /> ' samples collected from soil borings MW2, MW3, or MW4 <br /> Analytical results are summarized in Table 1 Laboratory data sheets and chain-of-custody <br /> documentation is presented in Appendix C <br /> w w2577Veprts\n=t aw 4 <br />