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borings will be advanced and soil samples collect from 0 to 6 inches, 12 to 18 <br /> inches, and 30 to 36 inches below ground surface (bgs). Soil samples collected <br /> r from each depth interval, within each area, will be composited by the laboratory <br /> prior to analysis. A total or six composite samples, one sample from each interval <br /> per area, will be analyzed for total mercury by EPA Method 7470 using cold <br /> vapor atomic adsorption. <br /> Collect two discrete soil samples, from one of the two areas suspected to contain <br /> elevated levels of mercury, to evaluate the leachability of mercury in soil. Collect <br /> surface and shallow surface soil samples from 0 to 6 inches and 18 to 24 inches <br /> bgs. The two discrete soil samples will be analyzed for total mercury by the <br /> r California Waste Extraction Test(WET) method, modified, using deionized water. <br /> Collect one bulk grab sample of surface material (0 to 6 inches bgs), from one of <br /> the two areas suspected to contain elevated levels of mercury, for physical <br /> separation testing. The bulk sample collected will be visually inspected and <br /> placed through a series sieves to assess grain size distribution of mercury-laden <br /> material. <br /> Soil samples will be analyzed by MBT Environmental Laboratories in Rancho Cordova, <br /> California. MBT Environmental Laboratories is a State of California Department of Toxics <br /> Substances Control-certified laboratory. <br /> i <br /> 3.3 TASK 3 - GROUNDWATER SAMPLE COLLECTION AND ANALYSIS <br /> This task consists of collection and analysis of in-situ groundwater samples from <br /> r <br /> immediately below and downgradient of the two areas suspected to contain elevated levels of <br /> mercury in soil based on the previous investigations (Figure 3). The groundwater gradient <br /> direction will be estimated based on regional information. Groundwater sampling procedures <br /> and protocols are described in Section 4.0. Shallow in-situ groundwater samples will be <br /> collected and analyzed as described below. <br /> • Collect two in-situ groundwater samples, one sample from below each of the two <br /> areas suspected to contain elevated levels of mercury in soil, to assess potential <br /> impacts to groundwater. <br /> SAC 187.14 3 <br /> DAMES & MOORE <br />