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16 2.3 Site Hydrology <br /> Site hydrologic data developed during the initial site assessment and subsequent groundwater <br />' quarterly monitoring events indicate that the gradient at the site is relatively flat and that the <br /> groundwater flow direction is to the northeast The reported historical high water elevation for <br /> the Site is approximately 25 feet below grade. During the initial groundwater sampling event <br /> in November 1992 groundwater was encountered at approximately 30 feet below grade. In June <br /> 1993, following substantial precipitation bringing an end to a seven year drought, the <br /> groundwater elevation increased approximately four feet to approximately 26 feet below grade. <br /> The groundwater elevation has fluctuated less than one half foot from June 1993 to September <br /> 1993 <br /> 3.0 SOEL INVESTIGATION <br /> Soil borings and a vadose zone well were constructed at the Site on October 18 and 19, 1993. <br /> A total of eight soil borings were advanced throughout the site and one vadose well was <br />' constructed adjacent to the northern end of the former excavation Soil borings were drilled to <br /> a maximum depth of 28 feet below ground surface, and the vadose zone well was constructed <br /> at a total depth of 28 5 feet below grade The soil boring location map with soil analytical data <br /> is shown in Figure 2 <br /> Soil boring SI-1 was advanced adjacent to the potential source area Soil boring SI-2 was <br /> centrally located within the site adjacent to the former excavation Soil borings SI-5, SI-7 and <br /> Sl-8 were located along the eastern property boundary Soil borings SI-3 and SI-6 were <br /> advanced along the western property boundary Soil boring SI-4 was advanced at the northern <br /> extent of the Site The vadose zone well was located adjacent to the potential source area, east <br /> of the former excavation <br /> Prior to any field work a Health and Safety Plan, required by OSHA regulations, was updated <br /> to reflect the proposed site activities The Health and Safety Plan included a task risk analysis <br /> and an emergency response plan. Underground Service Alert (USA) was contacted to notify <br />' utility companies to mark underground utilities at the drilling locations <br /> 3.1 Soil Sample Analysis <br />' The soil samples collected were analyzed for TPH-G by EPA Method 8015 Modified and for <br /> BTEX by EPA Method 8020 <br />