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ARCADIS Ms. Amaru June 1, 2010 • TPH as motor oil by USEPA Method 8015B (M) • Moisture content by American Society for Testing and Materials (ASTM) Method D-2216(so that results can be presented on a dry weight basis) All primary samples were analyzed upon receipt at the laboratory. All contingency samples were held at the laboratory pending the results of the primary samples, and were tested if necessary. The Site Sampling and Soil Removal Work Plan proposed the collection of grab groundwater samples from three borings (ARCADIS, 2010); however, groundwater was not encountered in any borings at 8 feet bgs. Therefore, no grab groundwater samples were collected. Soil Sampling Results As detailed in the Site Sampling and Soil Removal Work Plan and in the responses to the RWQCB comments(dated April 7, 2010), the soil sample results were compared to the following screening levels: • RWQCB, San Francisco Bay Region Environmental Screening Levels (ESLs) for shallow soils with residential land use for petroleum hydrocarbons • USEPA Regional Screening Levels (RSLs) (2009) for BTEX The results from the primary samples were compared to the screening levels as stated above. With the exception of three samples, the results for all primary samples were not detected above laboratory reporting limits or were detected at concentrations below screening levels (Table 1). The three samples containing concentrations above screening levels were collected from borings C51-SB2 and C51-SB4. The sample collected from 5.5 to 6 feet bgs in boring C51-SB2 contained a TPH as motor oil concentration of 210 milligrams per kilogram (mg/kg), which is above the ESL of 83 mg/kg. Two samples collected from boring C51-SB4 (from 5.5 to 6 and 7.5 to 8 feet bgs)contained TPH as gasoline, TPH as diesel and TPH as motor oil concentrations as high as 8,200 mg/kg. Based on the results of the primary samples, four contingency samples were analyzed for the following: Page: 3/8