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Page 3 <br /> June 27,2023 <br /> Brusca File No. 260-004 Workplan for Additional Plume Definition <br /> groundwater samples will be tested for gasoline, diesel, and motor oil-range petroleum <br /> hydrocarbons by EPA Method 8015B as well as volatile organic compounds (VOCs) by EPA <br /> Method 8260B, including MTBE. <br /> Completion of Soil Gas Assessment <br /> As requested in the referenced CVRWQCB letter, completion of soil gas sampling/testing at the <br /> SG3 location will be performed. The soil gas sampling, testing, and evaluation will be performed <br /> in accordance with the procedures outlined in our previous approved Workplan dated April 19, <br /> 2023.3 During the planned soil gas sampling at location SG3, a leak check gas (1,1 difluoroethane <br /> [DFA]) will be introduced beneath the shroud during sampling. A sample of ambient air will be <br /> collected beneath the shroud to evaluate the 1,1 DFA concentration within the shroud for the <br /> purpose of determining the significance (i.e., percentage) of any 1,1 DFA leakage detected in the <br /> soil gas sample. <br /> The soil gas sample collected from location SG3 will be analyzed for VOCs (including the tracer <br /> gas 1,1 DFA) by EPA Method TO-15 and oxygen by ASTM Method D1946. The air sample <br /> collected within the shroud will be analyzed for 1,1 DFA by EPA Method TO-15. <br /> EVALUATION AND REPORTING <br /> The data obtained during the described additional investigation will be tabulated and evaluated. <br /> A technical report will be prepared which will include: descriptions of the procedures and <br /> observations; scaled site plan drawings; boring logs; the laboratory data; discussion regarding the <br /> results and conformance of site conditions to Low-Threat UST Closure policy (LTCP) criteria; <br /> and, the signature and stamp of the Professional Geologist in charge of the project. <br /> CLOSING <br /> This Workplan will be submitted to the CVRWQCB for review and comment prior to <br /> implementing the work. Additionally, we will upload this document to the State Water <br /> Resources Control Board's GeoTracker database system. <br /> s Brusca Associates, Inc.; "Workplan for Additional Investigation, Area of Removed Underground Fuel Tank, <br /> Anderson Barngrover Ranch Property, APN 091-030-130m 14290 East Comstock Road, Linden, San Joaquin <br /> County,California";April 19,2023. <br />