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PROBLEM ASSESSMENT REPORT <br /> Moreland Court Shell <br /> 7700 Moreland Court, Stockton, California <br /> Delta Project No 40-88-146 <br /> Page 16 <br /> ' Based on the data collected from soil borings, former product line trenches, and the former underground <br /> storage tank excavation, the extent of petroleum hydrocarbons in soil at the site has been estimated The <br /> ' approximate horizontal extent of soil containing TPH concentrations is shown on Figure 3, two locations <br /> have been identified beneath the former tank locations near sample TS-2 and beneath the former product <br /> ' lines for the outer pump island near samples PL-5 and PL-6 <br /> 4.2 Distribution of Dissolved Constituents in Ground Water <br /> Two soil borings were advanced to 40 and 70 feet below grade and left open overnight with the augers in <br /> place to determine if water was present at these intervals Neither boring had accumulated water A shallow <br /> ' monitoring well was installed to an approximate depth of 40 feet below grade on August 2, 1990 within a <br /> wet silty sand zone The well was screened from 25 to 40 feet below grade across a suspected perched water <br /> ' table Measurements collected from monitoring well MW-1 on two occasions in August 1990,indicated that <br /> the well was dry <br /> Analytical results of TPH, BTEX,and halogenated volatile organics from a ground water sample collected <br /> ' from the water supply well located on site, approximately 20 feet west of the product line trench, indicated <br /> that the analyses were below the analytical method detection limits <br /> ' 5 0 CONCLUSION <br /> During the tank closure process, chemical analyses of soil samples PL-5, PL-6, and TS-2 revealed TPH <br /> ' concentrations of 1,130, 117, and 1,030 ppm, respectively In order to evaluate the extent of petroleum <br /> hydrocarbons detected, Delta drilled soil borings SB-7 through SB-10 and MW-1 near these locations <br /> ' Chemical analyses of soil samples collected from these soil borings at depths of 10 to 70 feet below grade <br /> yielded TPH concentrations below the method detection limit Depth to ground water was determined to <br /> be greater than 70 feet Chemical analysis of a ground water sample collected from the on-site water supply <br /> well did not detect petroleum hydrocarbons <br />