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I Di SANG Trucking RLport August 31 1995 Page 4 6 j" Condor presumed the height of the water column was governed by the top of the water I column (12 97 ft bgs prior to system start-up) and the top of the silt at 16 0 feet bgs Therefore, the height of the water column above the confining layer in August, 1995, was approximately 3 feet ' Based on an estimated porosity of 40% for medium sand (Todd, Groundwater Hydrology, 1980) and homogenous conditions, the cylindrical area of influence following the removal of approximately 3,800-gallons of water from MW 1 would have a radius of approximately 11 6 feet The cylindrical ' area of influence following the removal of approximately 15,700-gallons of water from MW1 would have a radius of approximately 23 6 feet The estimated areas of influence are shown on Figure 2, ' Appendix A ' 4.0 GROUNDWATER SAMPLING Samples were collected on August 16 and 22, 1995, following the removal of approximately 3,800-gallons and 15,700 of groundwater from MW1, respectively Prior to sample collection, the ' gear pump was turned off and the static water level in MW1 was measured to the nearest 0 01-foot with a battery-operated, flat-tape, water-level meter The water level measurement indicated, in ' both cases, the depth to groundwater was at least 80% of the pre-system start-up measurement The groundwater sample was collected with a new, disposable bailer The groundwater sample was transferred to 40-m1 glass VOA vials fitted with Teflon-lined caps and Miter glass bottles Each W` vial was inverted and tapped to assure that no air bubbles were present The samples were labeled and placed in a cooler chilled with Blue Ice and delivered under chain-of-custody procedures to ' GeoAnalythcal Laboratories, Inc , in Modesto, California, within 24 hours of sample collection One trip blank was carried in the cooler in which the groundwater samples were placed In both instances, the trip blank was returned, unopened, to the laboratory 4.1 Laboratory Analyses ' The groundwater samples were delivered to GeoAnalytical Laboratories, Inc , in Modesto, California The samples were analyzed for benzene, toluene, ethyl benzene, and xylene (BTEX) by ' EPA Method 602 and for total extractable hydrocarbons, quantified as diesel, kerosene and motor oil (TEPH) by Method 3510/LUFT ' 4.2 Results of Analyses Laboratory analyses of the groundwater sample collected from MW1 following the removal ' of approximately 3,800-gallons of groundwater detected 0 48 mg/1 diesel The groundwater samples collected from MW I following removal of approximately 15,700-gallons of groundwater detected no evidence of hydrocarbon contamination at or above the laboratory reported detection limits The ,0 results of the laboratory analyses are listed in Table 1 1 R ' �� CONDOR