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18 February 1992 (GenAudit CV 55-59 E2-1..32) Page 2 of 3 SAMPLE COLLECTION AND ANALYSIS Discrete soil samples were collected ahead of the drill bit using a split-tube sampler loaded with three brass sample tubes. Samples were collected at approximately 10, 20, and 30 ft; one additional sample was collected in SB-2 at 35 ft. The lead tube was first screened for hydrocarbon odors using an organic vapor meter (Thermo Environmental Instruments Model 580A) and then covered with � aluminum foil, capped, and sealed with duct tape before labelling and placing them on ice pending transport for laboratory analysis. The second tube was extruded a3,d examined by the field geologist. Sample descriptions are shown on the attached boring logs. Samples were transmitted to WEST laboratories for analysis. Samples were analyzed for the presence of heating oil using EPA metl:oJ 8015 modified for diesel and For the presence of volatile hydrocarbons (BTEX compounds) using method 8020. The chain-of-custody document is attached to this report. RESULTS � Both borings penetrated medium to dark-brown, generally well-sorted fine-grained to very fine-grained sand in the upper 18 €t. Some clay or clay clasts were also observed in auger returns and a few samples. Most samples emitted moderate 4o strong diesel odors. PID readings were generally low, ranging up to 25 ppm. A more dense clayey layer is present at about 18-22 ft, which decreased drilling rates through this interval. Clayey fine-grained sand was dominant in auger returns and in the samples at 20 ft. Strong diesel odors were present. From 22-30 ft, both borings penetrated medium to light-brown or light yellow-brown medium to coarse-grained sand. Downward, grain size increased, the color became lighter, and hydrocarbon odors decreased. At 35 ft, boring SB-2 recovered light yellow-brown silt; no diesel odor was present. As shown in the attached laboratory report, no volatile hydrocarbons were detected in analysis 8020. Samples SB-1-10 and SB-2-10, which were located within approximately 5 ft of each other because of the criss-cross drilling pattern, both had diesel concentrations of 14,000 ppm and motor oil concentrations in excess of 6,000 ppm. At 20 ft, the diesel concentration increased to 16,000 ppm 1n SB;;;l and......-the- motor---oil --concentration constant. In SB-2, both ,diesel and motor oil concentrations decreased to roughly 50% of their values at 10 ft. Below 20 ft (13 ft true vertical depth) , contamination levels decreased in both borings; no contamination was detected in sample SB--2-30. The