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Work Plan for Shallow Soil Assessment and Proposed Well Sampling Schedule Modification <br />Stockton Charter Way Commingled Plume #CP0057 <br />February 17, 2023 <br />equipment will be cleaned between each sampling interval. Soil encountered during drilling will <br />be continuously screened for hydrocarbon vapors using a PID and described using the Unified <br />Soil Classification System by Stantec field staff, working under the supervision of a Stantec <br />California Professional Geologist. If elevated PID readings are encountered, additional soil <br />samples may be collected, or borings may be extended deeper for further assessment. Soil <br />samples will be collected in 2 -inch diameter by 6 -inch long brass sample sleeves. Soil samples <br />collected for laboratory analysis will be sealed with Teflon@ sheets and plastic caps, then <br />labeled and placed on ice in an insulated container for delivery to a California state -certified <br />environmental laboratory under proper chain -of -custody (COC) documentation. <br />Upon reaching total depth of the borings, the boreholes will be tremie grouted from total depth <br />to grade with neat cement grout. The boring will be completed at the surface with concrete <br />dyed to match existing grade. <br />2.2.1 Soil Sample Analyses <br />Soil samples will be transported on ice to Eurofins Calscience Laboratories, Inc. (Eurofins), a <br />California state -certified laboratory. Samples will be analyzed for gasoline range organics (GRO) <br />by Environmental Protection Agency (EPA) Method 8015M; benzene, toluene, ethylbenzene, <br />and xylenes (collectively BTEX), methyl Cert -butyl ether (MtBE), Cert -butyl alcohol (TBA), di - <br />isopropyl ether (DIPE), ethyl Cert -butyl ether (ETBE), Cert -amyl methyl ether (TAME), ethylene <br />dibromide (EDB), 1,2-dicholorethane (1,2 -DCA), and naphthalene by EPA Method 8260B. <br />® Stantec 6 <br />