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ARCADIS Ms. Amaru February 19, 2010 Based on the results of the samples collected from the excavated soil, there appears to be impacts in the soil related to the lube oil storage tank or gas condensate storage tank that were formerly located in the lube oil tank berm area. Therefore, TPH and BTEX are the potential site constituents of concern (COCs). Metals are not expected to be COCs based on the sample results from December 2009 and historical site use. Proposed Sampling Activities ARCADIS proposes to conduct soil sampling around the area of the initial excavation to delineate the horizontal and vertical extent of petroleum-impacted soil. Prior to initiating sampling activities, a site-specific health and safety plan will be prepared for use during the proposed field activities, in accordance with state and federal requirements, and boring/well permits will be obtained from San Joaquin County.An Underground Service Alert ticket will be issued for the site, and a private, third-party, utility locator will screen all proposed boring locations to identify potential conflicts with underground utilities. Site personnel will also be consulted regarding information pertinent to underground utilities at the plant. A total of 18 step-out soil borings(12 primary and 6 contingency)will be advanced within and around the existing excavation to a total depth of 8 feet below ground surface(bgs)using a hand auger.The primary soil borings(SB-01 through SB-12) will be advanced near the edge of the existing excavation, and the contingency soil borings(SBA 3 through SBA 8)will be advanced approximately 7 to 10 feet from the existing excavation (Figure 2). Samples will be collected from each boring at depths of 2,4, 6 and 8 feet bgs.Table 1 summarizes the selected analyses for each sample and identifies which samples will be considered primary and contingency samples. In addition, grab groundwater samples will be collected from three borings(SBA 3, SBA 4 and SBA 7)in order to characterize groundwater quality upgradient and downgradient of the existing excavation.The groundwater samples will be collected by inserting a slotted polyvinyl chloride(PVC)casing into the boring and using a disposable polyethylene bailer to collect the groundwater sample. One grab groundwater sample will be collected from each of the three borings, for a total of three samples(Table 1).After sample collection, the casing will be removed. Depth to groundwater at the site is estimated to be at approximately 8 to 9 feet bgs. Page: 3/7