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IN =4857 .7'7;91 ". 5 ., .- , �a ' .. i "F SSB 91.1038 77Ytifty oil Company Station No. 172 Page 13 7647 Pacific Avenue Stockton,California 5.0 CONCLUSIONS On the basis of our findings,we present the following conclusions: 1) The soil profile at tl',e site consists of black,organic sandy clay to a depth of 5 feet, underlain by brown, silty sands to 10 feet, underlain by poorly graded sands to 20 feet, silty sands and sandy silts to 60 feet,and poorly graded sands at 60 feet. 2) Concentrations of petrolcurn hydrocarbons were indicated by analysis of soil samples from all soil borings. The highest concentrations of all compounds were detected in MW-2 (boring S-2) between 20 and 45 feet. Low to trace levels of compounds were detected in all other roil samples analyzed to a depth of 60 feet. The lateral extent of soil contamination was not defined. 3) The concentration of barium detected in the TCLP extract from the sample collected from MW-2(boring E-2) is beiow regulatory levels for toxicity as set forth in 40 CFR 261.24. The highest concentration of total lead detected (9 mg/kg)docs not exceed the current 7MC value. 75-rLCt 0 n^-° 4) The ground-water gradient as determined front elevations of the ground-water surface in June, 1991, was approximately 0.0017 feet per foot toward the cast- south—it. 5) 'I71e results of chemical analysis of water samples indicated coliform concentrations in excess of MCLS as identified in Section 64423, Title 22 of the CCR. 6) The results of chemical analysts for water samples analyzed for each of the four monitoring wells indicated high concentrations of petroleum hydrocarbons for all samples analyzed. The lateral extent of affected ground water was not determined. µ SSr/L•NVIRONMENTAL CONSULTANTS,INC.