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..'rElls. r ria= FE� :' "X :$' ..t.. SON V FI 1R RFPOR ANp Ir NK CLOSURi? SPUR" Tracy Boulevard Shell 3725 Tracy Boulevard,Tracy,California Delta Project No.4049.012 Pagc 15 The groundwater pumped was discharged into two 20,000-gallon aboveground storage tanks. Della collected a water sample from each storage tank,as required by the Wastewater Discharge Permit issued by the City. Each water sample was analyzed for TPH and total oil and grease to insure that the maximum concentrations allowed by the City Municipal Code were not exceeded. Table 12 presents the analytical ✓" results,and Appendix L presents laboratory data sheets. Concentrations of BTEX,TPH,and total oil and grease in the sample collected from Tank 1234(Table 12) were below standards allowed by the:City Municipal Code. The water was discharged on May 24, Il directly to the sanitary sewer lateral located on site. The concentt:.tion of benzene in Tank TR-log was 2 ppb;the City standard is I ppb. The water in this tank was filtero3 through a treatment system consisting of aqueous-phase carbon and resampled on May 24, 1990. Tic benzene concentration in this sample was less than 0S ppb and the water was then discharged on May 25,1990,to the s.^.nitary sewer lateral. Water from both tanks was discharged at the rate of approximately 40 gallons per minute. i i 5.0 SUMIARX OF RPSULTS The site geology,hydragmlogy,and soil and ground water sample laboratory analyses are discussed below. 5.1 Geoff a. Examination and classification of the soil samples and auger cuttings from 15 soil borings drilled at the site and observations made during station reconstruction indicate that the geology consists predominantly of silt, clay,clayey silt.and silty clay to a depth of 13 feet below the ground surface. Underlying tht:finer-grained soils are silty sands which were observed to a depth of 21 feet in most of the soil borings. 5.2 Ground Water Flow The water table was observed to be approximately 9 to I I feet below the ground surface in monitoring wells MW-I, MW-2, and MW-3 (Tabic 2). Three sets of water Ievel measurements were collected on September 26 and October 13, I999. and April 27, 1940. The direction of ground water now on September 26 and October 13,1989,was to the north-northeast at a gradient of 0.001,and on April 27, 1990, to the northeast at a gradient of 0.02. A ground water table contour map for September 26, 1939, is -:..---- - - .-..---------- presented..in.-Figure-6.__.._-...---- -..-- -- -- - - ----- — Depths to the water table in replacement monitoring wells MW-lA.MW 2A,and MW-3A was observed to be approximately 9 to 11 feet on August 28.1990(Table 2). The direction of ground water flow was to the northeast at a gradient of 0.001. A ground water table contour map is presented in Figure 7.