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J Ms. Lori Duncan Page 4 of 6 4.0 RESULTS OF INVESTIGATION 4.1 Subsurface Conditions The uppermost 6 feet of the soil's profile consisted of lean clay. Underlying the lean clay, coarse- grained soil classified as well graded sand and silty sand extended to depths of approximately 15 to 16 feet bgs. At approximately 15 feet bgs, a cemented clayey sand (hardpan) formation was encountered. This formation extends to unknown depths. No petroleum odors or discoloration were noted in the samples collected from borings S132 through SB5. FID readings from these samples ranged from non-detectable to 2 parts per million(ppm). A moderate petroleum hydrocarbon odor was noted in the sample collected from boring SB 1 at a depth of approximately 10 feet. Soil at this depth had a black color and an FID reading of 200 ppm. Subsequent soil samples examined below 10 feet bgs had no odors or discolorations. Soil boring logs are included in Attachment A. 4.2 Laboratory Analysis Soil samples were analyzed for total petroleum hydrocarbons as gasoline (TPHg) using EPA method 8015; total oil and grease (TOG) using method 5520; benzene, toluene, ethylbenzene"and xylenes (BTEX) using EPA method 8020; and volatile organic compounds (VOC's) including - gasoline oxygenate additives using EPA method 8260 4.3 Soil Analytical Results The only soil sample with detectable contamination was collected from boring SB 1 at a depth of approximately 10 feet bgs. This sample contained concentrations of TOG, TPHg, 1,1,1 trichloroethane and naphthalene of 17,000 ppm, 3.9 ppm, 0.44 ppm and 0.14 ppm, respectively. TEX was also detected, but at minor levels. Non-detectable levels were reported for benzene and . gasoline additives. Analytical results of soil samples are summarized in Table 2. Laboratory reports and chain of custody documentation are included in Attachment B 5.0 SUMMARY • No detectable amounts of target analytes were found in borings SB2 through SB5 nor in the sample collected at a depth o 17 feet in boring SB I. • TOG was detected in sample SBI-10 at elevated levels; however, no benzene or gasoline additives were detected. TPHg, TEX and VOC concentrations were minimal in this sample. • Rapid attenuation of soil contamination is evidenced by the decrease in analyte concentrations in boring SBL Nsautolrepo tslsummary_WP.doc