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r <br /> , A <br /> RECEIVED <br /> J U L 16 1990 <br /> ENVIRONMENTAL HEALTH <br /> WORK PLAN PERMIT/SERVICES <br /> FOR OFF-SITE GROUNDWATER MONITORING WELL INSTALLATION <br /> ARCO STATION 2093, TRACY, CALIFORNIA <br /> This work plan has been prepared by Brown and Caldwell for ARCO Products Company <br /> (ARCO) to install four off-site monitoring wells, one on-site groundwater extraction well, and <br /> drill two on-site soil boreholes at ARCO Station 2093, located at 3425 Tracy Boulevard, Tracy, <br /> California (site). Figure 1 shows the location of the site with respect to major streets and <br /> highways in the area. Figure 2 shows the proposed off-site monitoring well and on-site borehole <br /> locations. <br /> The work plan will be submitted to ARCO, the San Joaquin County Public Health Services, <br /> Environmental Health Division (County); and the State of California Regional Water Quality <br /> Control Board, Central Valley Region (Regional Board) for review and approval. Before <br /> commencing work at the site, all necessary permits will be acquired from the involved agencies. <br /> Work will commence within 30 days upon approval of this work plan, contingent on obtaining <br /> landowners' permission. <br /> The work plan describes the purpose and scope of the investigation and Appendix A <br /> provides a description of Brown and Caldwell's standard operating procedures for the work <br /> proposed. <br /> At least 48 hours prior to commencement of work, Underground Service Alert will be <br /> notified by telephone. Figure 3 is a map showing all of the known major utilities in the <br /> immediate area where drilling will occur. <br /> PURPOSE <br /> The purpose of this investigation is to more fully determine the lateral extent of soil and <br /> groundwater contamination, both on site and off site. This information will be used to further <br /> define the extent of hydrocarbon-affected groundwater around the site in order to develop an <br /> effective remediation plan. Extremely low concentrations of 1,2,-dichloroethane (1,2,-DCA)have <br /> been identified in the groundwater from three of the seven existing on-site groundwater <br /> monitoring wells. This phase of the investigation will include sampling for this constituent to <br /> determine its lateral extent in the soil and groundwater. The source of the 1,2,-DCA is unknown <br /> at this time. <br />