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Report on Additional Excavation and Go3mirmati on Soil Sampling Bulk Transportation Facility, Stockton, California Hygienetics Environmental Services,Inc. 2.4 Additional Excavation and Sampling at Southern Satellite Dispenser At the suggestion of Mr. Wong and with the verbal authorization of Mr. Woods of Bulk Transportation, Foss performed additional excavation at the former location of the' southern satellite dispenser. This additional excavation was done to remove the residual concentration (42 ppm) of diesel hydrocarbons that was found at a depth of 4 feet below grade in October 2002. i Soil was removed to a depth of 6 feet below grade and Hygienetics collected sample {. S-6-Dispenser S from the native soil at the base of the excavation. Plate 3 shows the location at which this sample was collected. The sample was sealed, labeled, and placed on ice as previously described and was included on the Chain-of-Custody form with the soil samples from the pipeline trench excavation. ! ;3 2.5 Laboratory Analyses ! Hygienetics delivered the seven soil samples collected from the two excavations and the five soil f samples collected from the stockpiles of soil to McCampbell!Analytical, Inc. (McCampbell) in Pacheco, California. McCampbell is a California-certified analytical laboratory (Certificate No. 1644). The seven excavation samples were each analyzed for TPHd using Environmental ' Protection Agency (EPA) modified Method 8015 and for BTEX�using EPA Method 8020. Stockpile soil samples S-Stockpile-A, S-Stockpile-B, S-Stockpile-C, and S-Stockpile-D were composited into one sample in the laboratory and analyzed for TPHd and BTEX. i Discrete sample S-Stockpile-1 was also analyzed for TPHd and BTEX.ii } i C3.0 RESULTS OF WORK� 3.1 Laboratory Analytical Results C II F } Laboratory analytical results show no detectable concentration of TPHd or BTEX was found in any of the six soil samples collected from the pipeline trench excavation. "'Further, no TPHd or BTEX I� was detected in the soil sample collected at the location of the'former`southern satellite dispenser. C • Table 1 presents these analytical results and Appendix B contains a copy of the laboratory report. Laboratory analytical results show the composite sample from the soil stockpile contained 700 ppm TPHd and did not contain detectable BTEX. The individual soil sample from the northeri stockpile contained 1,400 ppm TPHd and also did not contain detectable BTEX. These results are presented in Table 1 and a copy of the laboratory report is in Appendix B. I� 3.2 Estimated Mass of Diesel Hydrocarbons Removed The in-place volume, density, and concentration of TPHd in the stockpiled soil were used to calculate the mass of diesel hydrocarbons removed. The in-pIace volume of soil removed from # the excavation is estimated to be approximately 85 cubic yards. This quantity assumes a 30 C percent expansion of the soil volume (to 110 cubic yards) occurred during excavation and stockpiling. A typical in-situ density for silt and clay soils is ,95 pounds per cubic foot. j Laboratory analytical results show a concentration of 1,400-;ppm (or milligrams per kilogram) L TPHd was found in the discrete soil sample collected from the northern stockpile and,'based on field observation, approximately 40 in-place cubic yards of;the excavated soil are assumed to f contain this concentration. Using the above quantities and converting from milligrams per t 3� 5 C I� 3