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' 20 March 2015
<br /> AGE Project No. 00-0769
<br /> ' Page 16 of 19
<br /> ' • Ammonia, dissolved sulfide, orto-phosphate, and fluoride were not detected
<br /> above laboratory reporting limits in the groundwater samples collected during the
<br /> baseline and four subsequent sampling events (Table 5).
<br /> ' • Dissolved concentrations of bromide, bromate, chlorine, nitrogen, sulfate, TDS,
<br /> COD, conductivity, and total alkalinity in well MW-8A_all increased significantly
<br /> during the pilot test compared to baseline concentrations detected in June 2013.
<br /> ' The baseline concentrations detected in groundwater samples collected from
<br /> MW-8A in June 2013 were all extremely low; bromate was not detected above
<br /> the laboratory reporting limit (1.0 mg/1), TDS was detected at 90 mg/I and
<br /> ' a conductivity was detected at 93 umho/cm; the other ions were all detected at
<br /> very low concentrations, significantly below concentrations detected at all other
<br /> ' well locations and significantly below concentrations detected at MW-8A during
<br /> the four subsequent sampling events. It is unclear why baseline concentrations
<br /> were extremely low, but based on the data collected at the site and specifically at
<br /> ' well MW-8A following baseline sampling, AGE concludes that baseline data
<br /> collected from MW-8A in June 2013 may be erroneous or shallow groundwater
<br /> was effected by other sources (water line leak or waste water/surface water).
<br /> ' • A significant reduction in dissolved concentrations of TPH-g, BTEX, TAME, and
<br /> 1,2-DCA was observed at well MW-5A (screened 20-40 feet bsg) at the
<br /> conclusion of the ozone injection pilot test compared to baseline concentrations.
<br /> ' Well MW-5A is located approximately five feet from the closest ozone injection
<br /> well (OZ-4: screened 36-40 feet bsg) and in the general vicinity of OZ-5 through
<br /> OZ-8. TPH-g concentrations decreased from 25,000 pg/I in June 2013 to 630 fag/I
<br /> ' in October 2014 (97% reduction); BTEX concentrations decreased from
<br /> 4,500 pg/I, 140 pg/l, 550 fag/l, and 1,160 pg/I, respectively in June 2013 to
<br /> concentrations of 15 pg/l, 20 pg/I, 7.8 pg/l, and 39 pg/l, respectively in October
<br /> ' 2014 (85% to 99% reduction); and 1,2-DCA concentrations decreased from 91
<br /> pg/I in June 2013 to 2.0 fag/I in October 2014 (97% reduction). Trend graphs
<br /> illustrating dissolved TPH-g, benzene, and 1,2-DCA concentrations versus time
<br /> ' in MW-5A are presented in Appendix F; the ozone pilot test operational period is
<br /> depicted in the graph.
<br /> ' • Well MW-1 (screened 30-50 feet bsg) is located in the same general vicinity as
<br /> MW-5A and ozone wells OZ-4 through OZ-8A, however different results in
<br /> dissolved concentrations of TPH-g, BTEX, TAME, and 1,2-DCA were observed in
<br /> ' samples from well MW-1 at the conclusion of the pilot test compared to baseline
<br /> concentrations. TPH-g concentrations decreased from 150,000 pg/I in June 2013
<br /> to 130,000 pg/I in October 2014 (13% reduction); benzene concentrations
<br /> decreased from 18,000 pg/I in June 2013 to 15,000 pg/I in October 2014 (16%
<br /> reduction), but toluene, ethylbenzene, total xylenes, TAME, and 1,2-DCA
<br /> concentrations increased between the same period. However, the increased
<br /> ' concentrations were still within the normal range of concentrations detected
<br /> during previous sampling events. Additionally, concentrations of all the analytes
<br /> detected in well MW-1 during baseline sampling in June 2013 were low
<br /> Advanced GeoEnvironmental Inc.
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