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Ms. Margaret Lagorio,SJCEHD January 5,2005 Work Plan for Additional Site Assessment and Project No. 2033-15600-01 Evaluation of Remedial Alternatives Joe's Truck Plaza,Lathrop,California Page 5 • Contract with a California-licensed well driller (C-57 license) to install the proposed wells. • Update the site-specific Health and Safety Plan. • Secure permits from SJCEHD to perform the drilling and well construction activities. • Mark the proposed well locations and notify Underground Service Alert at least 48 hours in advance of the scheduled field activities. • Secure a permit to discharge extracted water to the sanitary sewer during feasibility testing. • Secure a permit from the San Joaquin Valley Unified Air Pollution Control District (SJVAPCD) to discharge treated soil vapor to the atmosphere during feasibility testing. Task 2: Soil Borings and Monitoring Well Installation Activities Drilling Activities Three borings (MW-9 through MW-11) will be drilled to the base of Sand A (approximately 15 feet bgs), and one boring (MW-8)will be drilled to the base of Sand B (approximately 40 feet bgs). These borings will all be completed as monitoring wells, as described below. All borings will be advanced using a truck-mounted drilling rig equipped with 8-inch diameter hollow-stem augers. To advance the boring for well MW-8, a 12-inch diameter boring will be advanced approximately 5 feet into the fine- grained material at the base of Sand A (approximately 20 feet bgs), and a steel conductor casing will be installed and cemented in place. The 8-inch diameter augers will be advanced through this conductor casing to complete the well boring. The proposed monitoring well locations are shown on Figures 2 and 3. The initial 5 feet of each boring will be advanced with hand tools, air knife, or water knife to reduce the possibility of damaging underground utilities. At a minimum, soil samples from each boring will be collected at 5-foot intervals during drilling using a California-type, split-spoon sampler, fitted with three pre-cleaned brass tubes. The sample tubes will be filled by drilling to the desired sampling depth, then driving the sampler ahead of the augers. After retrieving the sampler, the ends of the bottom-most, intact tube from each sample interval will be lined with Teflon TM sheets, capped, and sealed. Each sample will then be labeled, placed in a resealable plastic bag, and stored in an ice-chilled cooler. The samples will remain chilled and strict chain-of-custody procedures will be followed from the time the samples are collected until the time the samples are relinquished to the laboratory. K:Uoe's Truck Plaza\Work PlansUoes workplan 010505.doc