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1 Unlike samples taken from an open pit the five boreholes were designed to permit systematic and impartial sampling Open pit sampling, typically is determined by visual and olfactory tbias This bias will tend force to sampling in the areas that show the worst case for the site Generally, samples from hand auger borings and excavation walls are taken in areas having the ' greatest degree of contamination. Very rarely are the directed samples taken in an area that appears "clean" For this reason the samples taken from excavation are typically "high" for the site Blind sampling, is designed to access the site without prejudice This yields a more ' valid site characterization Anal is i Results ' Results of the general chemical analyses for the in-situ soil survey are presented in Table 1 In Table 1, sample identification corresponds to the identification codes used for the field sample ' distinction and identification in the laboratory reports (Appendix B) The prefixed portion of Sample Code is that which corresponds to the sample locations on the site map (Figures 3) Suffix portion involves depth of sampling Sample Date is the date the sample was taken ' TPH is the result, reported in milligrams per kilogram (mg/kg), of total petroleum hydrocarbons analyses for soil samples TPH analyses were done by EPA modified method 8015 ' Results of compound specific chemical po pec analyses for o the excavation are also presented in Table 1 As in Table 1, the presentation format includes the sample codes for map location Analyses are for the individuals constituents, benzene, toluene, xylene (total), and ethylbenzene The values are for analyses reported in milligrams per kilogram (mg/kg). The ' analyses were done by EPA method 8020 Anal. ical Data Evaluation and Discussion It is believed by Dufour Environmental that the analytical results generated by this investigation and their evaluation provide an adequate profile of the distribution and characteristics of the contamination on site Stockpile(s) generated during the excavation of 1988 have limited documentation There are no indications of any stockpile characterization rendered Soil samples taken on the day of tank removal appear to be the only previous sampling performed Two soil samples were taken during the excavation of the UST. Laboratory analysis was performed on these soil samples in the form of EPA methods 8015 and 8020. One soil sample taken at the base of the excavation pit indicated nondetectable levels for all specie of Total Petroleum Hydrocarbons, and BTX&E One sample taken from the excavation wall indicated 9,800 mg/kg Total Petroleum Hydrocarbons - Diesel form, and all other tests with this sample produced nondetecable values It is not well documented which wall the sample was taken form, but based on the diagram illustrated in the "Inspection Report" by Laurie Cotulla of the San Joaquin Local Health Department, dated 30 June 1987, with the nature of the warehouse wall in the diagram, the DUFOUR ENVIRONMENTAL AND RESOURCE MANAGEMENT PCP LODI CANNING UST CLOSURE GSA 31PCP LODI SAM 10 JULY 1991 4