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that will facilitate site closure. Because benzene is the only aromatic that exceeds <br /> drinking water standards, it is the focus of this investigation. <br /> It is suspected that the source of the aromatics is the Tank #3 vicinity. This is <br /> indicated by soil samples containing aromatics (toluene) detected down to the water table <br /> in a boring advanced near Tank #3. However, the monitoring wells that have had <br /> detectable concentrations of aromatics are also located downgradient of Tanks #1 and <br /> #2, in addition to being adjacent to Tank #3. Previous sampling efforts in the Tank #1 <br /> and #2 area appear to be poorly documented, and there is the.possibility that <br /> soil samples were collected from too shallow of a depth to.detect whether a release had <br /> occurred from. these tanks. <br /> The Tank #4 vicinity is not considered a potential source of aromatics because <br /> { aromatics have not been detected in the water samples from wells in this vicinity (MW-3 <br /> and MW-5) nor have they been consistently detected in the soil samples collected in this <br /> vicinity following the soil excavation. <br /> 4.4 PROPOSED SCOPE OF WORK <br /> E <br /> A soil vapor investigation will be conducted to 1) investigate whether the Tank #1 <br /> I <br /> and #2 vicinity is a potential source area, and 2) to evaluate the lateral and vertical <br /> I <br /> extent of aromatics and TPH in' the vadose zone. A survey of production wells for j <br /> municipal, domestic, industrial, and other uses within 2,000 feet of the site is required for <br /> site closure (Tri-Regional Guidelines, Appendix B) and does not appear to have been <br />} <br /> performed to date. Such a survey is proposed in this work scope to facilitate site closure. <br /> In addition, it is proposed that a level survey be conducted to establish an accurate top- <br /> of-casing reference elevation for MW-4. F <br /> R4182OA-1222950-4 <br /> soilvap.pin 4 <br /> 9 <br />