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ri p k�J Jb WORK PLAN FOR SOIL CHARACTERIZATION MAR :2 4 1989 AND PRELIMINARY GROUNDWATER REMEDIATION ARCO STATION 434, ON\%IRONME€`IAl.HEAT;H 541 KETTLEMAN LANE, LODI, CALIFORNIA PPki\hirlSER\/ICE,S This work plan has been prepared for ARCO Products Company (ARCO). The work plan will be submitted to ARCO, the San Toa uin Environmental Health Department (County), and the California Regional Water Quality Control Board, Central Valley Region (Regional Board) for review and approval. This work plan summarizes available inforriiation regarding soil and groundwater contamination at ARCO Station 434 and describes the objectives of the proposed work. The work plan describes the methods to be used in the field, including borehole drilling, soil sampling, well installation, well development, and groundwater sampling. The work plan also presents a quality assurance and quality c ntrol plan for sample collection, which includes sample handling and decontamination procedures in the field. This plan proposes a project schedule for work at the site and the submittal of reports to the regulatory agencies after the completion of the work. A site health and safety plan is also included with this. work plan. Before commencing work at the site, all necessary permits will be acquired from the County. BACKGROUND The location of ARCO Station 434 and the locations of nearby water supply wells are shown on Figure 1. According to the former statin manager, the site has been a service station since 1941. Elevation at the relatively flat project site is about 42 feet above sea level. The area is immediately underlain by Quaternary-age alluvial deposits. These deposits consist of complexly interbedded and int fingered sands, silts, and clays. The freshwater aquifer occurring in these deposits is unconfined and occurs throughout the region. The regional groundwater flow direction ranges from south to west. Depth to groundwater is approximately 55 feet. In December 1986, a loss of approximately 800 gallons of unleaded gasoline resulted from a product line leak at Station 434. The esti ate of the amount lost was calculated from ARCO inventory data for November and December 1986. The leaking product line was replaced. The location of the leak site is shown on Figure 2. AIso shown on Figure 2 are the locations of the existing and fo er underground storage tanks (USTs), existing on-site groundwater monitoring wells, former soil boreholes, proposed additional soil boreholes, and proposed groundwater extraction well. Following the reported loss of product, the City of Lodi (City) took nearby Well 12 (Figure 1) out of service. Well 12 has remained out of service.