ARCHIVED REPORTS XR0000012 - Laserfiche WebLink

Home Browse Search

If I V\kV D A S S O C I A T E S I N C 3.0 SUBSURFACE CONDITIONS ' 3_1 Geology Soil in bonngs MW i and MW3 consisted of poorly graded sand with silt from the surface to 6 5 1 to 10 feet bgs Soil from depths between 6 5 to 10 feet bgs and 31 feet bgs consisted of well graded sand Soil from depths between 31 feet bgs and 31 5 to approximately 34 feet bgs consisted of lean clay Soil from depths between 31 5 to 34 feet bgs and 36 to 36 5 feet bgs, the maximum depths explored, consisted of elastic silt with sand Soil in boring MW2 consisted of poor to well graded sand with varying amounts of silt from the ' surface to 35 feet bgs Soil from depths between 35 feet bgs and 38 feet bgs consisted of elastic silt Soil from depths between 38 feet bgs and 39 feet bgs consisted of silt with gravel Soils from depths between 39 feet bgs and 40 feet bgs consisted if silt Soil from depths between 40 ' feet bgs and 45 feet bgs, the maximum depth explored, consisted of silt with sand 3_2 HYdrogeology Water level measurements were collected from wells MW 1 through MW3 on January 29, 1999 Water levels ranged from 19 17 to 19 57 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 south-southwest The average hydraulic gradient on January 29, 1999 was calculated to be 0 0002 ft/ft or approximately 1 ft/mile A summary of groundwater monitoring data is presented in Table 2 ' 4.0 ANALYTICAL RESULTS ' 4_1 Soil Analytical Results Soil samples collected from borings MWl and MW3 contained very low to nondetectable concentrations of TPHd (1 3 and 1 1 part per million (ppm)) Soil samples collected from borings MW1 and MW3 contained no detectable concentrations of TPHg, BTEX, or oxygenate fuel additives Soil samples collected from boring MW2 contained slightly elevated concentrations of TPHd and TPHg The analytical results indicated the TPHd concentrations contained diesel and non diesel compounds The analytical results also indicated the TPHg concentrations were weathered gasoline Soil samples collected from boring SB2 from between 19 feet and 30 feet bgs contained low concentrations of ethyl benzene and xylenes The deepest soil sample collected from boring MW2, at 44 5 feet bgs, did not contain detectable concentrations of TPHg, BTEX, or ' oxygenate fuel additives Oxygenate fuel additives were not detected in any samples from boring MW2 Analytical results of soil samples are summarized in Table 1 w\130991reporls\sumwe1 dm 4