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a <br /> In the early development of bioremediation formulations of ORC, several independent laboratories and universities <br /> participated in proof-of-concept studies indicating that ORC releases oxygen, enhances microbial activity, and <br /> promotes remediation. Subsequently, field applications demonstrated that ORC was effective in promoting <br /> bioremediation under"real world"conditions. <br /> ■ University of Waterloo (published, Groundwater Monitoring and Remediation, Winter 1994) — Conducted at the <br /> widely studied Borden Aquifer in Ontario, Canada, the study indicates that an Oxygen Barrier generated by ORC <br /> released significant amounts of dissolved oxygen (DO). It concluded that the enhancement of DO by ORC led to the <br /> biodegradation of at least 4 mg/L each of benzene and toluene. <br /> ■ North Carolina Site (published, Proceedings from the Second International Symposium on In Situ and On-Site <br /> Bioreclamation, San Diego, CA, 1993) — This study demonstrated that the use of ORC in an Oxygen Barrier <br /> dramatically reduced BTEX compounds downgradient from a UST generated gasoline spill. <br /> ■ Alaska Site (presented at the I&EC Special Symposium, American Chemical Society, Atlanta, GA, 1995) — A pilot <br /> study showed the effectiveness of an ORC remediation compared to air sparging. Sparge points fouled in the high <br /> iron environment and there was evidence of channeling — a problem common with this technology. ORC was <br /> effective in remediation and a full barrier was installed. Benzene levels were reduced from 320 ppb to 9.8 ppb and <br /> total BTEX went from 1361 ppb to 17 ppb. Gasoline range organics went to NO (not detected)from 7.4 ppm. Diesel <br /> range organics rose from ND to.55 ppm, indicating there may have been an influx of hydrocarbons during the test. <br /> ■ New Mexico Site (presented at The New Mexico Environment Department UST Bureau Bioremediation Conference, <br /> Santa Fe, NM 1995) — At this site, ORC was installed in 20 wells to form an Oxygen Barrier. There was a high <br /> contaminant flux at the site (5-15 ppm at 1-2 feet per day). DO increased from inadequate levels and was <br /> maintained at 10 ppm and greater for the first 30 days. After 93 days the estimates of the remaining oxygen <br /> indicated that a change out of ORC would not be required for six months. During this 93 day period, a significant <br /> reduction of BTEX mass was achieved in the treatment zone, such that concentrations of total BTEX in samples <br /> from the most downgradient well (measured at 120 feet from the barrier) declined to NO. At this well, assays of <br /> aerobic microbial degraders were two orders of magnitude higher than background, thus indicating the presence of <br /> oxygen from the ORC installation was driving bioremediation. <br /> ■ 15-Site ORC Performance Evaluation—ORC was placed in 41 existing wells on 16 sites and monitored for a 7 to 12 <br /> week period. The average dissolved oxygen levels were significantly increased; two-thirds of the readings were <br /> between 20 and 30 ppm, even while in the presence of dissolved phase BTEX. As expected,the BTEX levels dropped <br /> dramatically-between 80 and 100 percent in 75% of the wells-a third of those being fully remediated (see Figure 4). <br /> 16-SITE ORC PERFORMANCE EVALUATION <br /> Average DO Increase (41 Wells) Average BTEX Degradation (41 Wells) <br /> 25 m 5000 - <br /> 64LKGROUNO <br /> ¢25CURRENT z a,000—� 4,700 <br /> 0 29 _ <br /> j 15 3.000 <br /> ¢ 10 Nam a <br /> ¢ 2,000 CURRENT <br /> � 2 3]1 <br /> f' S w 1,000 <br /> a <br /> 0 d 0 <br /> AVERAGE 00 AVERAGE BTEX <br /> Figure 4 these graphs illustrate the results of the 16-site ORC Performance Evaluation program described above. <br />