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sT� „q�,,�x � �F � �:��� � n .,,s'�' -td ��xev. z � ���`,.'r,s` .�'E"�S�n��' .�' <,a*•� ::r <br /> w.�?.....-�3F... <br /> B <br /> 1 <br /> Docauea significant concontrotiont of TPU were found In toile at <br /> dept.h% of up to 31 foot balov around aurfaco, and bvcause then <br /> water table wars more than 33 feet below ground surface, in-Ri;u <br /> rerodiati.on of the hydrocarbon contaminated coil was solectod (or <br /> this site, during the• vook of 7 Novombor 1988, five 0011 vapor <br /> extraction vailn M-vS, Figure 2 ) were installed in and around <br /> the former tank field (Figura 2) for the purpozo of onsite, in- <br /> Placo extraction and troatmont of contamInatad coil gar., with the <br /> ultimata goal of significantly reducing the hydrocarbon concen- <br /> t.ations in the coil. Theno fives wells were screened bolow the <br /> tank excavation backfill (about 15 foot depth) to a total depth <br /> of approximately 34 feat. The coil boring logs and the well <br /> f <br /> completion diagrams for the five vapor extraction walla are <br /> included as Appendix A. <br /> On 25 April 1909, pilot-scale touting to determine design para- <br /> rasters for a vapor extraction oyster. at the site was initiated by <br /> EA. A vacuum compressor capable of pumping 30 cubic foot per <br /> minute (cfm) was attached to vapor extraction wells vz, V4, and <br /> V5, all locatod outsider the backfilled tank excavation. Samplau <br /> of the vacuum discharge were collected and analyzod onsite using <br /> EA's mobile HNU gap chromatograph. Vapor samples from V2 con- <br /> tained up to 4,503 ppm total petroleum hydrocarbons (TPN); V4 <br /> contained TPH in concentrations ranging from 40,000 to 63,500 <br /> ppm; and samples from V5 averaged approximately 16,000 ppm TPN. <br /> In addition to vapor concentration measurements, the vapor trans- <br /> missivity of the; soil was tested the same clay. To that and, soil <br /> vapor probes were driven to depths of approximately 15 feet and <br /> 25 feet below ground surface at 5 and to feet from well V3 in the <br /> direction of well V4. These probes were slotted the bottom six <br /> inches of length and equipped on the surface with sensitive <br /> magneholic gauges to Peasure vacuum pressure in the soil <br /> resulting from the vacuum applied to veli V3. In addition, a <br /> magnehelic gauge vas connected to well V4, 22 feet from the well <br /> V3. A vacuum flow of about 22 to 30 cfm was then applied to well <br /> 052/9191 flrt ext <br />