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1 <br />' tank area. Stockpiled soils were placed on visqueen, sampled, and <br /> covered with additional visqueen. <br /> Investigation Activities <br />' w retained b Catellus Development Corporation to <br /> ERM-West as reta y P <br /> investigate the extent of the release at Site #2 and to assess the need <br />' for remediation. Two phases of investigation have been conducted by <br /> ERM-West. The Phase I investigation conducted in March 1992 <br /> included the installation of four ground water monitoring wells and <br />' the collection of soil samples from the monitoring well borings. In <br /> addition, an December 1992, a geophysical survey was conducted at <br /> Site #2 to identify the potential presence of any buried objects which <br /> could represent another source for a release of chemicals to soil or <br /> ground water. The Phase II investigation conducted in April 1993 <br /> included the installation of one additional monitoring well and four <br /> soil borings. Both phases of investigation are described in detail <br /> below <br /> Phase I Investigation <br /> Four ground water monitoring wells were constructed at the site by <br /> ERM-West during the Phase I investigation conducted on March 27 <br /> and 28, 1992. The wells were installed an locations that would enable <br />' ERM-West to obtain the maximum amount of information needed to <br /> characterize the sods and ground water at the site. This section <br /> describes the preparatory work performed prior to initiating field <br />' activities, the monitoring well construction and drilling activities, <br /> and the soil and ground water sampling procedures. <br /> EMEaWtign for Fic-ld Activities <br /> 1 Preliminary work for the Phase I investigation included preparing <br /> an Investigation Workplan and a sate-specific Health and Safety <br /> Plan, and retaining contractors responsible for drilling and <br /> laboratory services. Preparatory work also included obtaining the <br />' necessary permits, locating underground utilities, and relocating the <br /> soil stockpile that was situated above the former tank. <br />' The Investigation Workplan specified the steps to be followed during <br /> field activities (Appendix J). A copy of the request letter from San <br /> Joaquin County EHD is included in the Workplan The contractor <br />' responsible for the drilling activities was Spectrum Exploration, Inc., <br /> located an Stockton, California. Jam Dobbas, Inc. was utilized to <br /> move the soil pile that overlies the site of the tank excavation. ERM- <br /> 5-3 <br /> 1 <br />