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i a n <br /> WORK PLAN <br /> FOR OFF-STTIi GR,01,:.NDWA'TER 1IC)aN'1T()RIM; wrLL INSTALLATION <br /> RC( <br /> STATION 2093, TRACY, CALIFORNIA <br /> J� <br /> This work plan(has been prepared by Brown and Caldwell for ARCO Products Company <br /> (ARCO) to insLdl-fiytr off-site monitoring wells, one on-site groundwater extraction well—and <br /> drill two on-site. sail boreholes at ARCO Station 2093. located at 3125 'Tracy Boulevard, Tracy, <br /> California (site). Figure I shows the location of the site with respect to major streets and <br /> highways in the area. Figure; 2 shows the proposed off-she monitoring well and on-site borehole <br /> locations. <br /> The work plan will be submitted to ARCO. the San Joaquin County.Public health Smices. <br /> Environmental Health Division ' <br /> County); and the State of California Regional Vater Quality <br /> Control Board, Central Valley Region (Regional Board) for review and approval. Beforc <br /> commencing work at the site,all necessary permits will be acquired from the involved agencies. <br /> Work will cr)mmcnce 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 /> t At least 43 hours prior to commencement of work, Underground Service Alert will be <br /> nodfied 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 remediadon plan- Extremely low concentrations of I,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,-JCA is unknown <br /> at this time. <br />