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x t= A S S O C I A T E S I N C between 16 feet bgs and 26 5 to 30 feet bgs consisted of poorly graded sand and well graded sand with silt Soil from depths between 26 5 to 30 feet bgs and 81 5 to 85 feet bgs consisted of lean ' clay and lean clay with sand, with elastic silt with sand found between 56 5 to 60 feet bgs and 61 5 to 65 feet bgs Soil from depths between 61 5 to 65 feet bgs and 81 5 to 85 feet bgs consisted of lean clay and lean clay with sand Soil from depths between 81 5 to 85 feet bgs and t86 5 feet bgs, the maximum depth explored, consisted of poorly graded sand Lean clay and lean clay with sand was encountered in soil boring MW3 in the upper 11 feet of the ' soil column Soil from depths between 11 feet bgs and 16 feet bgs consisted of poorly graded sand with silt Soil from depths between 16 feet bgs and 36 to 40 feet bgs consisted of lean clay and lean clay with sand Soil from depths between 36 5 to 40 feet bgs and 46 5 to 50 feet bgs consisted of silt and silty sand Soil from depths between 46 5 to 50 feet bgs and 66 feet bgs consisted of sand with varying amounts of silt and clay Soil from depths between 66 feet bgs and ' 71 5 to 75 feet bgs consisted of lean clay and lean clay with sand Soil from depths between 71 5 to 75 feet bgs and 76 5 to 78 feet bgs consisted of clayey sand A grab sample collected off the drill bit from the bottom of the boring at 78 5 feet bgs consisted of lean clay 3_2 Hydrogeology Water level measurements were collected from wells MW 1 through MW3, on November 16, t 1998 Water levels ranged from 62 35 to 63 34 feet below the tops of the well casing elevations The water level data were used to develop the groundwater elevation contour map (Figure 3) Assuming that horizontal isotropic conditions prevail, groundwater in the uppermost aquifer beneath the site flowed towards the southwest The average hydraulic gradient on November 16, 1998 was calculated to be 0 004 ft/ft or approximately 21 ft/mile A summary of groundwater ' monitoring data is presented in Table 2 I 4.0 ANALYTICAL RESULTS ' 4.1 Soil Analytical Results ' Soil samples collected from borings MW 1 and MW3 contained nondetectable to very low concentrations of TPHg and BTEX constituents Soil samples collected from boring MW2 contained elevated concentrations of TPHg and low concentrations of BTEX constituents The ' highest concentrations of TPHg and BTEX constituents were between 20 feet and 60 feet bgs The deepest soil sample collected from boring MW2, at 85 5 feet bgs, did not contain detectable ' concentrations of TPHg or BTEX Oxygenate fuel additives were not detected in any samples from borings NMI, MW2, or MW3 Analytical results of soil samples are summarized in Table 1 ' 4.2 Groundwater Analytical Results Groundwater samples collected from wells MW1, MW2, and MW3 contained elevated concentrations of TPHg. and BTEX Concentrations of TPHg ranged from 56,000 parts per W li 6393VeporWsumi doc 4 1