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25 January 2012 AGE-NC Project No. 02-0926 Page 6 of 7 events (Table 6). Ground water levels measured throughout the pilot test did not indicate the presence of mounding within shallow ground water at the site. Lack of mounding in shallow ground water wells can likely be a product of the depth of pilot test sparging equaling 70 to 75 feet bsg. Depth to ground water measurements are summarized in Table 3. Based on dissolved oxygen measurements collected during the pilot sparging, significant increases in dissolved oxygen were observed in shallow well MW-5. Based on these results the location and depth of well MW-6 should provide adequate increases in dissolved oxygen further promoting remediation of the hydrocarbon-impacted ground water plume. Dissolved oxygen concentrations, which generally fluctuated in all other monitored wells (MW-1 through MW-4), likely indicates that the sparging radius of influence is limited. PID readings collected during pilot sparging activities indicated an overall increase in influent concentration (Appendix B). Furthermore, influent PID measurements collected during the pilot test were significantly higher in comparison to the previous six months of SVE operation conducted between April and October 2011 (Table 2). Increases in influent PID provide an indication that shallow hydrocarbon impacted water in the area of MW-5 was effected by pilot sparging and that dissolved hydrocarbons in water were stripped into a vapor phase recoverable by the onsite SVE system. .14LC4 A total of four influent and three vapor samples were collected during the 72-hour IAS pilot test. TPH-g and BTEX constituents were detected in all four influent vapor samples and were absent from the effluent sampling stream. Based on laboratory analytical data, influent vapor stream concentrations increased when compared to results from samples collected during SVE operation between June and October 2011. The increase in influent vapor stream, especially increases in BTEX concentrations is likely attributed to pilot sparging conducted at well MW-6. 6.0. RECOMMENDATIONS Based on the findings of the 72-hour air sparging test, AGE recommends preparation of a correction action plan (CAP) evaluating the feasibility of ground water remedial technologies for the site. Due to limited remaining annual funding for the site, AGE recommends submission of the proposed CAP during the third quarter 2012, as additional funds become available. Further, AGE recommends temporarily suspending ground water sampling until the third quarter of 2012. Advanced GeoEnvironmental, Inc.