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JVM ASSOCIATES WKA No 1735 01 April 22, 1992 Page 2 Tank Removal One 10,000-gallon diesel UST and one 7500-gallon diesel UST were removed from the site by Post Tank of West Sacramento, California on January 14, 1991 The 7500-gallon UST was reported to have contained unleaded gasoline at one time Laboratory analysis of soil samples obtained by our firm from beneath the tanks and the product lines revealed detectable concentrations of Total Petroleum Hydrocarbons(TPH) as diesel Laboratory results for the tank and product line samples are summarized in Table 1 A copy of our Soil Sampling and Testing report dated January 29, 1991, is included as Appendix A Soil Investi ation Six soil borings (B2-B4 and B6-B8) were completed on March 11, 1991, at the locations indicated on Plate 3 The borings were advanced to a depth of 31 5 feet below grade TPH as gasoline and Benzene, Toluene, Ethylbenzene & Total Xylenes (BTEX) were detected in samples obtained from Borings B2 and B3, TPH as diesel was also reported in Boring B2 Samples obtained from Borings B4 and B6-B8 revealed no detectable concentrations of TPH-gasoline, TPH-diesel or BTEX above detection limits Laboratory results for samples obtained from the soil borings are presented in Table 2 Results of this investigation are summarized in our Preliminary Investigation and Evaluation Report, dated April 4, 1991, included as Appendix B The soils beneath the site consist of clayey silts interbedded with one to three foot thick lenses of silty sand, well graded sands were encountered in Borings B7 and BS at a depth of approximately 30 feet Descriptions of soils encountered in the borings are presented in the boring logs included on Plates 4 through 6, an explanation of the Unified Soil Classification System used to describe the soils is presented in Plate 7 Soil Excavation Based on recommendations presented in our April 4, 1991 report, and upon approval by San Joaquin County PHS, excavation of petroleum hydrocarbon contaminated soil began on July 2, 1991 Excavation operations continued until July 23, 1991, when confirmation samples collected from the bottom and sidewalls of the excavation were analyzed and found to contain no detectable concentrations of TPH- gasoline, TPH-diesel or BTEX, with the exception of Sample S-42, which reported 0 69 mg/kg TPH- gasoline WALLACE KUHL Ree)ryeyatx> Er ASSOCIATES INC