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ENVIRONMENTAL CONSULTING & MANAGEMENT FtCX= 1855 GATEWAY BOULEVARD SUITE 770 CONCORD, CALIFORNIA 94520 510 602-2333 FAX# 510 687-1258 April 27, 1993 Mr. Harlan Knoll San Joaquin County Public Health Services Environmental Health Division 445 North San Joaquin Stockton, California 95201 Dear Mr. Knoll: On behalf of ARCO Products Company (ARCO), Roux Associates (Roux) has prepared this letter work plan to describe a proposed subsurface investigation at ARCO Facility No. 2093, located at 3425 Tracy Boulevard, Tracy, California (Site). The purpose of this investigation is to determine conditions with respect to the possible presence of petroleum hydrocarbons in soils at the Site. Roux proposes to drill and sample up to six soil borings in the area where ARCO plans to install new underground storage tanks at the Site (Figure 1). The borings will be drilled to a total depth of about 15 ft. below ground surface (bgs) with samples collected at 5-foot intervals. Roux will call Underground Service Alert (USA) to mark utilities in the immediate vicinity of the Site. The soil borings will be drilled by Wayne Drilling Company, a contractor licensed in the state of California as a Water Well Driller (C-57 No. 376345). Boreholes will be drilled using a truck-mounted drill rig equipped with 8-inch outside diameter, continuous flight, hollow stem augers. Samples for soil characterization and laboratory analysis will be collected in the boreholes at 5-foot intervals by driving a 21h-inch diameter, 18-inch long, California Modified, Split Spoon Sampler ahead of the auger. The California Sampler will contain three clean 2-inch diameter, 6-inch long, stainless steel liners. The number of blows to drive the sampler each 6 inches will be counted and recorded on the geologic logs. One stainless steel liner from each California Sampler collected will be retained for possible laboratory analysis. Immediately after the sampler is recovered from the borehole and opened, the ends of one liner will be covered with aluminum foil and plastic end caps. The ends will then be wrapped with duct tape. Each sample will be labeled with the Site location, date, time, identification code, and sampler's initials. Each sample will be placed in a plastic bag and stored on ice in a closed cooler chest while in transit to the laboratory. Chain-of-Custody documentation will be maintained for all samples. The contents of the remaining liners from each California Sampler and the auger cuttings will be examined by the field geologist. Soils from the samplers will be described using the Unified Doc #A159W01.1.3