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 10 of 19 • Utilizing site wells MW-4D, MW-6D, and MW-8D, groundwater was inferred to be flowing toward the northwest under an average hydraulic gradient of approximately 0.002 ft/ft. Figure 6 illustrates contoured groundwater elevations as measured on 04 August 2014. • TPH-g were detected in groundwater samples collected from wells MW-4D, ' MW-5D, and MW-6D at concentrations ranging from 2,800 pg/I in MW-6D to 58,000 pg/I in MW-4D. BTEX compounds were detected in the same samples at maximum concentrations of 22,000 pg/I benzene, 2,000 pg/I toluene, 670 pg/I ' ethylbenzene, and 1,940 pg/I total xylenes (MW-4D). • 1,2-DCA and TAME were detected in groundwater samples collected from wells MW-4D, MW-5D, and MW-6D at maximum concentrations of 550 pg/l 1,2-DCA 1 (MW-4D) and 260 pg/I TAME (MW-4D). • No additional analytes were detected above laboratory detection limits in the ' groundwater samples analyzed. HU-5: 193 feet to 198 feet bsq ' • Depths to groundwater were measured and groundwater samples were collected from HU-5 wells MW-4E and MW-5E. • Depths to groundwater were 22.95 feet (MW-4E) btoc and 23.70 feet (MW-5E) btoc (Table 1). Groundwater elevations were 12.60 feet (MW-4E) below NAVD88 and 12.84 feet (MW-5E) below NAVD88. ' • TPH-g were detected in groundwater samples collected from wells MW-4E and MW-5E at concentrations of 6,600 pg/I (MW-4E) and 3,400 pg/l (MW-5E). BTEX ' compounds were detected in the same samples at maximum concentrations of 560 pg/l benzene, 310 pg/l toluene, 250 pg/I ethylbenzene, and 900 pg/I total xylenes (MW-4E). • 1,2-DCA and TAME were detected in groundwater samples collected from wells MW-4E and MW-5E at maximum concentrations of 17 pg/I 1,2-DCA (MW-5E) ' and 11 pg/I TAME (MW-4E). • No additional analytes were detected above laboratory detection limits in the groundwater samples analyzed. The estimated extent of dissolved TPH-g, benzene, and 1,2-DCA for HU-1 through 9 HU-5 are illustrated in Figures 7 through 11, respectively. Analytical results of ' groundwater samples collected in August 2014 are summarized in Tables 2, 4, and 5. The laboratory reports (CTEL Lab Project. Nos. CT214-1408026 and 1408037), quality assurance/quality control reports, and chain-of-custody forms are included in Appendix E. EDF files and depth to water data were uploaded to the State GeoTracker database system. Graphs illustrating depth to groundwater, groundwater elevation and TPH-g concentrations versus time (trend graphs) for each hydrogeologic unit are Advanced GeoEnvironmental Inc.