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R *400 INTERIM WORKPLAN Arts and Artists 204 East Lodi Ave. BACKGROUND The site is located in a flat commercial area in central Lodi. It is our understanding that a 550-gallon underground fuel storage tank containing leaded gasoline was removed by Thorpe oil Co. in January, 1987, and that soil samples collected at that time were contaminated. Three groundwater monitoring wells were installed in August 1987 , and all showed evidence of contamination. By late 1991, two of these wells had gone dry, and were replaced by two new wells in May 1992. The new wells (MW-4 and MW-5) were sampled in July 1992, and contamination was detected. PROPOSED WELL LOCATIONS At the direction of San Joaquin EHD, we propose to install one monitoring well north of MW-4, and a second well east of MW-3 (Figure 1) . Data collected in 1987 indicate that these locations were down-gradient from the former UST at that time, but new data collected in May 1992 indicate that these locations are presently up-gradient from existing wells. The new wells will provide information on the eastern and northern limits of groundwater contamination. Details of the drilling and sampling procedures are provided below. 1) Drill two monitoring wells using truck-mounted, continuous- flight, 8-inch diameter hollow-stem augers and complete according to the well design shown in Figure 2 . 2) Obtain discrete soil samples at five-foot intervals in each boring, using a split-tube sampler loaded with three pre- cleaned brass tubes. 3) Decontaminate sampling equipment in a tri-sodium phosphate solution (TSP) and rinse twice with water prior to each sampling run. 4) Describe auger returns and soil samples in accordance with the Unified Soil Classification System on boring logs. 5) Visually examine soil samples, and use portable photo- ionizaton detector to screen samples for evidence of volatile organic hydrocarbons. 6) Preserve samples in the middle brass tube by covering both ends with aluminum foil, capping, and sealing with tape. 7) Label and log soil samples on a chain-of-custody form.