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Clayton <br /> C! SLlf4%14 <br /> The concentration of TRPH in the water sample collected from the exca ration pit <br /> was 2 ppm The groundwater sample was not analyzed tar gasoline or BTEX. <br /> 4.1.2 Overexcavation <br /> Based on the initial excavation, Clayton recommended additional excavation of sod <br /> from the north and east walls. The excavation in the vicinity of the north and east <br /> walls was deepened to approximately 12 feet below grade,where soil appeared to be <br /> clean based on visual observation and readings from the OVM In some areas, the <br /> M excavation was deepened below the water table. <br /> - The walls of the excavation were expanded to the north and to the east. On August <br /> 9, 1990, a concrete, underground septic tank was encountered. SJC/EHD and <br /> ° Interland Corporation were informed of the tank's existence. Clayton obtained a <br /> septic tank closure permit from the SJC/EHD on August 10, 1990. Ms. Diane Hmson <br /> of the SJC/EHD oversaw the septic tank removal and soil sampling on August 17, <br /> �- 1990. <br /> New confirmation samples were collected from the north and east walls after any soil <br /> s M that showed evidence of potential contamination was excavated. The excavation was <br /> deepened to approximately 13 feet below grade in the vicinity of the former septic <br /> tank (4 feet below the bottom of the tank). This overexcavation included the area <br /> - where sod sample ME-1 was collected. Clayton sampled the soil at 13 feet below <br /> grade (IT 4'-BT) <br /> r <br /> dIn total, the following six soil samples were collected from the overexcavation: <br /> _ • Augug-17. 1990: NE ', ME-2, SME-1, IT-6"-BT, and IT-4'-BT <br /> • August 28. 192f?: MN-2 <br />' The soil samples were analyzed by EPA Method 418.1, for TRPH Only samples ME- <br /> and MN2,were analyzed by EPA Method 503018015-8020, for gasoline and BTEX. <br /> Additionally, sample 1T=6"=BT, collected from 6 Inches below the former septic tank, <br /> was analyzed by the following-niethods- <br />��rPYa}s <br /> • EPA Method 8010, for purgeable halocarbons <br /> • EPA Method 6010, for total and soluble lead <br /> 1 The sample locations are indicated on Figure 3 Table 4 summarizes laboratory <br /> sx y= 4 results. Notable results are listed below. <br /> KA <br /> None of the arc constituents for which analyses were conducted were detected. <br /> a, • Sample IT-W-BT had lead concentrations well within background levels for soil <br /> A total of about 1,650 cubic yards of soil were excavated to achieve removal of soils <br /> with concentrations exceeding 3.6 mg/kg of gasoline and 80 mglkg of oil and grease. <br /> f <br /> 6 <br /> _i 7�wu0s.reV <br />