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• Pa Engineering Science, Inc. <br /> SECTION 3 <br /> PROPOSED INVESTIGATION ACTIVITIES <br /> GENERAL <br /> This section discusses the proposed site characterization activities which are designed to <br /> complete characterization of groundwater contamination in the northeast corner of the site <br /> and to provide sufficient information for determining suitable remedial alternatives for the <br /> low concentrations of TCE in groundwater associated with the northeast corner of the <br /> property. The objectives of the proposed additional remedial investigation are as follows: <br /> 1. Further evaluate the stratigraphy, particularly below depths of 60 feet in order to <br /> complete geologic cross-sections through this area <br /> 2. Analyze groundwater quality at a varietyof depths near p and downgradient of the <br /> sewer line <br /> 3. Investigate the vertical extent of groundwater contamination to an approximate <br /> of 110 feet PP ate depth <br /> r4. Evaluate potential migration of TCE and related compounds in groundwater off-site <br /> to the east of MW-4 <br /> POSITIONING AND RATIONALE FOR INVESTIGATION POINTS <br /> A total of seven CPT probes are proposed to address the data gaps described in the previous <br /> section. The planned sampling locations and depths are shown in Table 1 and on Figure 6, <br /> respectively. Two CPT locations, P-11 and P-12, are positioned adjacent to the sewer line <br /> near the east end of the parking lot in order to evaluate the vertical extent of contamination <br /> beneath the line. Groundwater samples will be collected at intermediate and shallow depths <br /> in these two holes. As shown on Figure 3, groundwater sample analytical results have been <br /> obtained at shallow depth adjacent to the sewer line from B-108, P-6, and MW-4. Figures 4 <br /> and 5 show that one sample analysis has been obtained from the intermediate depth at P-6 <br /> and no samples have been obtained from the deeper layers in this area. <br /> One proposed sampling point, P-13, is located off-site 100 feet north-northeast of MW-4 to <br /> check the lateral extent of downgradient migration and screen for any past northeasterly <br /> offsite migration that could have occurred if a more northerly orientation of the gradient <br /> formerly existed. The remaining four sampling locations, P-14 through P-17, are arranged <br /> 0997\09072\wks2add 12-18-97 <br /> 3-1 <br />