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(J 1 <br /> J <br /> collecting soil and/or groundwater samples for analysis of PHCs. Field, analytical, and <br /> historical data will be evaluated to determine the lateral and vertical extent of PHC impact in <br /> the soils and groundwater beneath each site. A Site Investigation and Evaluation Report will <br /> be prepared including documentation of field work and a summary of findings and <br /> recommendations. <br /> 3.1 FIELD INVESTIGATION <br /> The following sections describe the approach and methodology for the field 'investigation. <br /> Prior to initiating any field work, an application for "Permit to Construct Monitoring Wells <br /> and/or Soil Borings for the Purpose of Subsurface Investigation," will be submitted to and <br /> approval obtained from the PHS/EHD. <br /> 3.1.1 Approach <br /> Due to the unusually wet winters over the past few years, water levels in the vicinity of the <br /> site have risen substantially since the tanks were removed. It is anticipated that there will be <br /> only a small interval, if any, of unsaturated soils (vadose zone) between the bottom of the <br /> former excavations and the water table. If that proves true, then the subsurface investigation <br /> will focus primarily on evaluation of the lateral extent of PHCs in groundwater. <br /> 3.1.1.1 USTs <br /> In order to reduce the potential for contamination of groundwater due to penetration through <br /> contaminated soils and translocation of contamination by drill tools, an initial boring (115-1, <br /> Figure 2) will be advanced about 10 fest away from the location of the former tanks. In the <br /> initial boring, continuous core samples will be collected from the approximate depth of the <br /> bottom elevations of the former tanks to about 10 feet below the water table. These soil <br /> samples will allow characterization of the subsurface lithology and depth to groundwater at the <br /> tank site, and will provide target locations for collection of soil and groundwater samples in <br /> the subsequent two borings at this site. If the core sampling indicates that the water table is <br /> sufficiently below the bottom elevations of the former tanks, soil samples for PHC analysis will <br /> be obtained from the cores at 5-foot intervals starting at 2 feet below the bottom elevations of <br /> the former tanks and ending 2 feet above the water table. In addition, a groundwater sample <br /> will be collected from the first transmissive zone below the water table. <br /> If the water table is sufficiently below the bottom elevations of the former tanks, a boring will <br /> be advanced within the area of the former excavation near the south end of Tank #4, which <br /> 4 98117WUsrudv.V1W <br />