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i OF 04 1 WORK PLAN ARCO STATION 434 , LODI, CALIFORNIA s This work plan has been prepared for ARCO Products Company (ARCO) to conduct an investigation of soil quality at ARCO Station 434 in Lodi, California. The work pian will be submitted to ARC and the Environmental Health Division of the San Joaquin Local Health District (County). Before commencing work at the site, all necessary permits will i be acquired from concerned agencies. Work will commence within 30 days upon approval of this work plan. PURPOSE YThis work plan describes the proposed investigation of soil quality at the project site. The work proposed is part of an ongoing characterization of the extent of hydrocarbon contamination resulting from a product line leak, discovered and repaired in December 1986. Locations of existing groundwater monitoring wells and boreholes are shown on I Figure 1. Also shown on Figure l are the former and existing locations of underground storage tanks, piping, and pump islands. Laboratory analyses (U.S. Environmental Protection Agz;icy. (LPA) Method 8015, modified) of soil samples collected from monitoring wells W-1, W-2, and W-3 and from soil boreholes B-1 and B-2 are shown in Table 1. These were used in choosing proposed borehole locations. The purpose of this work is to determine the extent of hydrocarbons in soil in the vadose zone. FIELD METHODS f This section describes the field methods for this investigation, Borehole Drilling < Brown and Caldwell (BC) will supervise the drilling of nine boreholes at the site (see Figure 1). Boreholes will be drilled using a truck-mounted drilling rig equipped with 6-314-inch-outside-diameter, 3-1/4-inch-inside-diameter hollow-stem augers. All boreholes will be drilic d to. approximately 50 feet below ground surface. Groundwater fl_uctua_tes_ seasonally-between-about-50-and 60-feet low-ground-surface.--The borehtiles will 6e grouted with a bentonite/cement slurry placed by trernie pipe. j a. i C - _ s