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837 Shaw Road • Stockton, CA 95215 <br />Telephone (800) 511-9300 • Fax (888) 445-8786 <br />Project No. 14-3002 <br />Subject: Draft Trenching Scope of Work <br />Former SAN JOAQUIN COGENERATION <br />17200 Murphy Parkway, Lathrop, California <br />SCOPE OF WORK <br />AGI proposes to advance a total of 25 trenches at the subject property to locate and <br />identify buried waste. Initially, AGI proposes to advance 18 trenches in the southern area <br />of the site; 5 trenches in the stormwater retention basin; and 2 trenches along the west <br />and east sides of Murphy Parkway, west of the former power plant facility. Most of the <br />trenching locations and sizes were determined by AGI in consultation with EHD staff. Site <br />conditions and materials encountered may dictate final trenching locations and sizes. <br />Trenches will be excavated to total depths between five (5) and seven (7) feet below <br />surface grade (bsg) using a backhoe or mini excavator; trenches will vary in length <br />between 40 and 120 linear feet. Based on previous investigations, buried wastes have <br />been identified beneath the subject property starting at approximately 3 to 4 feet bsg in <br />the southern area of site. If waste is encountered, the trenches will be excavated further <br />laterally and to deeper depths to define the extent of the waste. Excavated soil will be <br />stockpiled adjacent to the trenches for inspection and sampling. Soil and waste (if <br />encountered) will be visually classified by AGI personnel in accordance with the Unified <br />Soil Classification System (USCS) or type of materials encountered and documented on <br />a trench log. <br />Following soil inspection and classification, samples will be collected from each trench <br />location by hand-packing the material into precleaned and certified, 4-oz, Teflon-lined <br />closure, wide-mouth clear glass sample containers (sample jars). The following is the <br />proposed sampling protocol: <br />Surface samples will be collected from each trench location every 40 linear feet <br />and analyzed for total PCBs (dry weight) by EPA Method 8082A. <br />One soil sample will be collected from the bottom of each trench location and <br />analyzed for total PCBs (dry weight) by EPA Method 8082A. <br />If waste is encountered in a trench, one waste sample will be collected and <br />analyzed for total PCBs (8082A) and dioxin/furans by EPA 1668; and the bottom <br />sample will be analyzed for total PCBs and dioxin/furans.