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3.5 Groundwater Sample Collection and Analysis ' Water samples were collected from each well using a new disposable plastic bailer Each water sample was collected in two 40 ml VOA vials and one 1-liter amber bottle Samples were transported in a chilled container to McCampbell Analytical, Irrc (MAI) to Pacheco, 1 California and analyzed for TPH as gasoline and diesel and BTE&X in accordance with EPA methods 5030 and 602, respectively ' 3.6 Monitoring Well Surveying On February 7, 1995, the relative casing elevations of all four monitoring wells were ' surveyed Monitoring well MW-1 was assigned an arbitrary elevation of 20 00 feet, other wells were surveyed relative to MW-1 4.0 FINDINGS ' 4.1 Stratigraphy Pea gravel was encountered in boring B-6 from approximately 6 to 12 feet The soil overlying the pea gravel was less compact than the soil penetrated elsewhere at the site indicating possible backfill material The boting may have penetrated the area of a former irrigation ditch Black tora la was encountered from. the surface to 10 feet in boring B-8 Two-inch togray clay cobbles with black clay was encountered in bot rng B-9 from apps oxiniately 2 to 6 feet Black to gray clay was encountered below the cobbles to 10 feet to boring B-9 A sewage odor was also observed in the black and gray clays in both B-8 and B-9 The presence of the cobbles and sewage odor suggests the presence of a septic leach line near the west side of the pump islands Flowing water was also heard in boring B-8 during dulling However, the current property manager indicated that the leach lines do not run near the pump islands Clay to silty clay was encountered in the remaining depths of all borings Bottng logs are included in Appendix A 4.2 Laboratory and Field Evidence of Impacted Soil Slight hydrocarbon odors were noted in samples from B-6 at depths from 6 to 12 feet (pea gravel) and at 15 feet Organic vapors were detected with the PID at concentrations up to 25 parts per million (ppm) TPH as diesel and motor oil were detected at a depth of 5 feet at concentrations of 36 ppm and 290 ppm, respectively TPH as diesel was detected at a depth of 15 feet at a concentration of 40 ppnn Benzene was detected at slightly above the detection limit at depths of 13 feet and 15 feet Slight hydrocarbon odors were noted in boring B-7 at a depth of 5 feet, Organic vapors were detected at a concentration of 38 ppm TPH as gasoline, diesel, motor oil and benzene were detected at concentrations of 2 0 ppm, SG94(R I01402UZI L..6..d F—d QR LA2 94