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BP Chemical, Advanced Materials Div., P.O. Box 6189, Stockton, CA October 20, 1992 Mr. Lon Kitagawa 3 excavation will not be required, and the excavated pit will be backfilled as described below in Section 2.5. If the analytical results indicate that the sidewall and bottom samples contain TPH-G and BTEX concentrations exceeding the clean-up goals, the excavation will be further extended approximately 2 feet in the vicinity of the sample(s) that contained hydrocarbons exceeding those limits. Additional samples will be collected and analyzed. This procedure will be repeated until petroleum hydrocarbon concentrations in sidewall and bottom samples are below those clean-up limits or until further excavation is not technically feasible. Soil Sampling As described above, soil samples from the excavation sidewalls and bottom will be collected to verify that the affected soil has been removed. Because the excavation will extend deeper than five feet below grade, and the sidewalls will not be stabilized with shoring, the field technician will not enter the excavation to collect soil samples. Instead, samples will be collected from the soil contained within the backhoe bucket. The soil collection method will consist of pushing a 2.5-inch- diameter, 6-inch-long stainless steel sampling tube into the soil within the backhoe bucket. The sample tubes will be sealed with plastic end caps and aluminized adhesive tape, and then immediately delivered (under chain-of-custody procedures) to the on-site mobile laboratory for chemical analysis. A minimum of three samples will be collected from the sidewalls and three samples from the excavation bottom are planned. Additional samples may be required if the initial samples contain concentrations of TPH-G or BTEX above the clean-up goals, and additional excavation is required. After the excavation has been completed, additional samples of the stockpiled soil will be collected and analyzed for disposal characterization. Four stockpile samples will be collected for the purpose of characterizing the soil for off-site disposal. Those samples will be analyzed as described below. Stockpile samples will be collected by pushing a stainless steel tube into the soil, sealing the tube with plastic caps and tape, and delivering the sample to the state-certified laboratory for analysis. The analytical results from the stockpiled soil will be submitted to the disposal facility for the appropriate waste characterization and waste profiling. Chemical Analyses To provide immediate analytical results, an on-site, state-certified mobile laboratory will be used to analyze the soil samples. Samples collected to verify the removal of soil samples with petroleum hydrocarbons will be analyzed using U.S. Environmental Protection Agency (EPA) Test Method 8015 Modified (for TPH-G with benzene, toluene, ethylbenzene, and xylene [BTEX] distinction). Because of analytical equipment restrictions in the on-site mobile laboratory and sample preparation procedures, additional tests will be performed at an off-site state-certified laboratory using EPA 01 GROUNDWATER TECHNOLOGY,INC.