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.,� - __ �s - �r '.t'�' _ tea.. .yr•� - - - ",��_. v Results of the laboratory analyses indicate that approximately one half of the estimated volume of soil " proposed for excavation has an average concentration of TPH (both gasoline and diesel range) of less than 100 ppm, and nondetectable to low levels of BTEX constituents. The laboratory results from this sampling activity are consistent with the results of previous sampling and analysis conducted by Kaprealian Engineering, Inc. (1988, 1989) . Most of the remaining soil proposes; for excavation had an average TPH-G or TPH-D concentration of less than 850 ppm, with only the 5- to 10-foot depth portions of Sections A and C with TPH concentrations exceeding 1,000 ppm. Both of the composite samples from these sections, however, were found to be nonhazardous based on the acute toxicity test performed in accordance with Title 22 of the California Health and Safety Code. Most of the composite samples from this portion of the proposed excavation area also had no detectable concentrations of BTEX, and low levels of total lead. Organic lead was not detected in the 5- to 10-foot sample from Section A. 2.3 5gi E cayation and Offsite Disposal Based on the results of the laboratory analyses of soil samples, all of Sections A and B, the 5- to 10-foot portion of Section C, and the 0- to 5-foot portion of Section F could be disposed of at a Class Il landfill, while .the remainder of the soil proposed for excavation could be disposed of at a Class III landfill. The total in-situ soil volume estimated for disposal was 5,000 cubic yards. The Liquid Waste Management, Inc. facility in McKittrick, California was selected as the Class II landfill, while the Durham Road Landfill in Fremont, California was selected as the Class III facility. On July 9, 1990, soil excavation was initiated. Balch f ; Petroleum, Inc. of Milpitas, California was contracted by Mobil Oil to perform the excavation under the supervision of Alton Geoscience personnel. Between July 9, and ., August 7, 1990, approximately 3,060 cubic yards of soil were hauled and disposed of at the Durham Road Landfill, and approximately 3,020 cubic yards of soil were hauled and disposed .of at the Liquid waste Management facility. Field ._....---observations-of -contaminant levels- in the-soil were generally consistent with with the results of the drilling and sampling activities, however, an estimated 525 cubic yards of soil originally designated for disposal at a Class III f,f.:ility, were eventually hauled to the Class II facility in McKittrick, California. Totalsoil volume discrepancies can be accounted for by a "fluff-factor" of 22 percent Copies �.° of the load profiles are included as Appendix C.