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OU 5 Work Plan <br />Spot <br />Check <br />Slide <br />Hammer <br />Passive Soil <br />Gas Survey Soil Vapor Soil Hydropunch <br />Explorations <br />0U5 SG-01 <br />through <br />0U5_SG-18 <br />0U5_SV-01 and <br />OU5 SV-02 <br />OU5_12-42-HP, <br />OU5 MW-15, <br />OU5_MW-22, <br />OU5_MW-24, <br />0U5-SV-01, <br />OU5_SV-02 <br />Samples 18 2 6 6 <br />Analyses <br />TPH, <br />Chlorinated <br />Solvents <br />TPH, <br />Chlorinated <br />Solvents <br />TPH, Chlorinated Solvents <br />Prior to subsurface investigation, Kleinfelder will perform a Passive Soil Gas Survey (PSGS) with <br />sixteen Amplified Geochemical Imaging® (AGI, formerly known as the GORE-SORBERTM) <br />modules (Figure 0U5-1, 0U5_SG-01 through 0U5 SG-18). These modules produce chemical <br />mass values that correlate with concentrations. These mass value data will be used to <br />qualitatively assess relative differences in subsurface conditions prior to subsurface <br />investigations. This will allow Kleinfelder to collect data representing the highest concentrations, <br />better define concentration extents, and to avoid potential subsequent sampling and guide <br />potential remedial actions. <br />To assess expected ongoing natural attenuation, Kleinfelder will collect groundwater samples <br />from locations where previous timeseries concentration data were collected. Kleinfelder will <br />advance pushprobe explorations to collect Hydropunch samples in the location of initial Phase II <br />exploration 12-42, where Hydropunch data were initially collected, and at the locations of past <br />monitoring wells installed for OU 5 (Figure 0U5-1, 0U5_MW-15-HP, 0U5 MW-22-HP, and <br />0U5_MW-24-HP). <br />To define lateral and vertical contamination, Kleinfelder will also advance one pushprobe <br />exploration where the PSGS indicates the highest contamination concentrations and one where <br />PSGS indicates lowest contamination concentrations. Soil samples will be collected from these <br />locations at depths of 10, 15, and 20 feet bgs. Hydropunch groundwater samples will also be <br />collected from these locations, and soil vapor monitoring wells will be installed at two depths: One <br />about 3 to 5 feet above the water table and one about 5 feet bgs. These data will be combined <br />with similar data collected from OU 8 explorations, and a regression model will be developed to <br />calculate soil, groundwater, and soil vapor concentrations from the PSGS mass values. These <br />additional PSGS-based pushprobe explorations are subject to change after PSGS results are <br />available for analysis. <br />Based on proposed industrial use, depth of contaminated soil, and the concrete cap that will be <br />installed as part of the Site construction, Kleinfelder will base further recommendations on <br />groundwater and soil vapor data. These data will indicate either: <br />20173951.001A/SAC17R68420 Page 11 of 26 November 2, 2017 <br />© 2017 Kleinfelder www.kleinfeldercom <br />KLEINFELDER 2882 Prospect Park Dr., Suite 200, Rancho Cordova, CA 95670 p1916.366-1701 f I 916.366-7013