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w4- %we 13 September 2012 AGE-NC Project No.99-0682 Page 17 of 17 week of injections TPH-g and benzene constituents were not reported in well MW-8. However,TPH-g and benzene concentrations both rebounded and increased during each subsequent post-ISCO sampling event. The rebounding of hydrocarbon concentrations can likely be attributed to highly impacted and drowned adsorbed soil impact at the well screen depth. • TPH-g and BTEX decreased approximately 68% and 63%, respectively in well MW-10 as compared to baseline analytical data collected in April 2012. Based on historical groundwater monitoring results and results from samples collected during post-ISCO injection monitoring, it appears that ISCO injections effected downgradient dissolved hydrocarbon impact in the area of MW-10 (Appendix E). • Based on the ISCO pilot study field observations and monitoring data, the application of the hydrogen peroxide solution and modified fenton reagent solution (diluted hydrogen peroxide solution with acid) in injection wells at the site was effective at either decreasing dissolved hydrocarbon concentrations(MW-1 A, MW-7 and MW-10)or liberating residual drowned adsorbed hydrocarbons in soil (MW-8). Furthermore, based on decreasing hydrocarbon levels in observation wells MW-7 and MW-10, it appears groundwater in the downgradient area of the injection wells was also effected by the ISCO media application. 6.0. RECOMMENDATIONS Based on the above conclusions, AGE recommends preparation of an interim remedial action work plan(IRAW P)proposing ISCO injection to mitigate the remaining hydrocarbon- impacted groundwater and soil at the site. The IRAWP will detail additional ISCO injection well locations, well constructions and will detail procedures for full-scale implementation at the site. 7.0. LIMITATIONS Our professional services were performed using that degree of care and skill ordinarily exercised by environmental consultants practicing in this or similar localities. Findings were based upon analytical results provided by an independent laboratory. Evaluation of the geologic/hydrogeologic conditions at the site forthe purpose of this investigation was made from a limited number of available data points(groundwater samples and field parameters) and subsurface conditions may vary away from these data points. No other warranty, expressed or implied, is made as to the professional interpretations, opinions and recommendations contained in this report. Advanced GeoEnvironmental,Inc.