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12 July 2012 <br />AGE-NC Project No. 02-0926 <br />Page 6 of 7 <br />Laboratory Lab Project. No. 1204063 and 1205122), quality assurance/quality control <br />report, and chain-of-custody form are included in Appendix D. Analytical data was <br />uploaded to the State GeoTracker database under confirmation numbers 6034916698 and <br />5207563042. <br />5.0. CONCLUSIONS <br />Based on field data and laboratory analytical data from the March through May 2012 <br />extended 60-day IAS pilot test, AGE concludes the following: <br />Between 16 March and 16 May 2012, an electric air compressor and the on-site <br />SVE system were utilized for the performance of an extended 60-day IAS pilot test. <br />Approximately 17 psi of pressure was applied throughout the pilot test at well MW-6. <br />Sparged soil vapors were recovered throughout the test utilizing the site SVE <br />system and wells VW-1 and MW-5. <br />Ground water levels measured throughout the pilot test did not indicate the <br />presence of mounding within shallow ground water at the site. Lack of mounding in <br />shallow ground water wells can likely be a product of the depth of pilot test sparging <br />equaling 70 to 75 feet bsg. Depth to ground water measurements are summarized <br />in Table 3. <br />Based on dissolved oxygen measurements collected during the 72-hour pilot test <br />performed in December 2011 and the extended 60-day pilot test performed in <br />March and May 2012, significant increases in dissolved oxygen were observed in <br />shallow well MW-5 (Appendix C). During both pilot tests DO concentrations steadily <br />increased within well MW-5 indicating that communication between the sparge point <br />and the impacted well was occurring. Based on these results, monitoring well MW-6 <br />should be used in the future to remediate shallow zone dissolved hydrocarbon <br />impact near well MW-5. Additional shallow screened air sparge wells would be <br />warranted to expedite the remedial efforts in shallow zone water should full scale <br />air sparging commence at the site. <br />Based on analytical ground water data collected during the extended 60-day pilot <br />test, it appears that deeper air sparging liberated residual "drowned" adsorbed <br />hydrocarbon impacted soil in the area surrounding MW-5 and MW-6. TPH-g <br />concentrations were detected at concentrations as great as 1,200,000 pg/I, the <br />highest dissolved concentrations reported historically for the site. However, based <br />on samples collected during the June monthly pilot test sampling, BTEX <br />concentrations surrounding well MW-5 were significantly reduced (up to 90%) as a <br />result of the extended pilot study (Appendix C). <br />Advanced GeoEnvironmental, Inc.