ARCHIVED REPORTS - OZONE PILOT TEST & SEMI-ANNUAL GROUNDWATER MONITORING REPORT - THIRD QUARTER 2014

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' 20 March 2015 AGE Project No. 00-0769 ' Page 18 of 19 ' been 1,100 pg/I in December 2012 and 640 pg/I in October 2011. Trend graphs illustrating dissolved TPH-g, concentrations versus time for HU-1 through HU-5 are presented in Appendix F. ' • TPH-g concentrations in wells MW-5(B-C), MW-6(B-D), and MW-10 decreased moderately (37-70% reduction) at the conclusion of the pilot test. However, BTEX ' concentrations in all the above-mentioned wells either increased slightly or remained stable; and TAME and 1,2-DCA concentrations remained stable. Trend graphs illustrating dissolved TPH-g, concentrations versus time for HU-1 through ' HU-5 are presented in Appendix F. • TPH-g and various BTEX concentrations in wells MW-2A, MW-7A, MW-8A, and MW-9A increased slightly at the conclusion of the pilot test. However, ' concentrations were all very low and may demonstrate the influence of the ozone injection. ' The injection of ozone over the 183 day period reduced petroleum hydrocarbon concentrations significantly in wells that were in close proximity (5-15 feet) to ozone injection wells and had corresponding well screen intervals (MW-5A and OZ-4 through ' OZ-8); and in wells where ozone injection was capable of dispersing upwards through well screens (MW-3B and OZ-1 through OZ-3); while, at the same time increasing the DO and ORP concentrations in surrounding monitoring points. Additionally, ozone ' injection reduced petroleum hydrocarbon concentrations moderately in wells that had corresponding well screen intervals (MW-2B and OZ-4 through OZ-8; MW-10 and OZ-1 through OZ-3) but were not located in close proximity to an ozone injection point. ' The results of the ozone injection pilot test indicate that ozone can be a feasible J p e remedial technology at the site. However, additional ozone injection points, with depth- discreet well diffusers (deeper than long screened monitoring wells [e.g. MW-1]), installed in specific locations at the site would be necessary. Additionally, due to the ' high concentrations, large area and volume, and depth of impacted soil and groundwater at the site, AGE believes ozone remediation would need to be supplemented with an additional solute base ISCO/remediation technology (peroxide). t An additional ISCO technology (liquid: hydrogen peroxide or equivalent) would be capable of targeting impacted soil and groundwater in the deeper HU2 zone. ' Based on the results of the semi-annual groundwater monitoring and sampling event performed in August 2014, AGE presents the following brief conclusions: • On 04 August 2014, groundwater on-site was generally inferred to be flowing ttowards the northeast at an average gradient of 0.0008 ft/ft in HU-1; towards the south at an average gradient of 0.002 ft/ft in HU-2; towards the west-northwest at an average gradient of 0.001 ft/ft in HU-3; and towards the northwest at an ' average gradient of 0.002 ft/ft in HU-4 (Figures 3-6). Advanced GcoEnvironmental Inc. 1