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September 25, 1998 - Page 3 Subsurface Conditions Soils encountered during Geoprobe® installation and drilling (maximum explored depth of approximately 38 feet bgs) consisted primarily of silty sands, sand, sandy silt and sandy clay to the maximum depth explored Boring logs are presented as Attachment B Groundwater was first encountered at depths of approximately 14 to 15 feet below ground surface (bgs) and stabilized at 13 to 14 feet bgs Groundwater elevation data for the August 24, 1998 sampling event indicate that the direction of groundwater flow beneath the site is toward the north at an approximate gradient of 0 004 ft/ft Direction of groundwater flow, gradient, and contour elevation data are shown on Figure 2 Surveyor's data and map are presented as Attachment C Soil Analytical Results With the following exceptions, all soil samples were non-detect for all analytes tested TPH-g was reported in GP-2 at a concentration of 3 8 ppm at 25 feet bgs. MtBE was reported in MW-1 at a concentration of 0 0081 ppm at 28 feet bgs Soil analytical data is presented as Table 3 Soil analytical results are presented on Figure 3 Groundwater Analytical Results • GeoprobeO Grab Samples Two out of ten analyzed Geoprobe® groundwater grab samples reported TPH-g concentrations ranging from 4,700 to 7,400 ppb MtBE was reported in three samples at concentrations ranging from 0 64 to 20 ppb Tert-butanol was reported in GP-3 at a concentration of 36 ppb however, not detected in GP-2 No other oxygenates were detected in any of the analyzed samples • Monitoring Well Samples TPH-g was not detected in any of the analyzed monitoring well samples Benzene was reported only in MW-2 at a concentration of 0 51 ppb MtBE was reported in all three wells at concentrations ranging from 0 98 to 16 ppb No other oxygenates were detected in any of the analyzed samples All groundwater analysis was performed using EPA Method 8260 Groundwater analytical data is presented as Table 2 A groundwater concentration map is presented as Figure 4 Groundwater certified analytical reports and chain of custody documentation are presented as Attachment E Physical Parameter Analytical Results Soil physical parameter data is presented as Attachment E Stockpiled Soils Soils generated during well installation activities were transported by Manley and Sons Trucking to Forward Landfill in Manteca, California for treatment and disposal 911-007 1 B/SOLG W RPT