SITE INFORMATION AND CORRESPONDENCE_1985-1997

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0 0 . # ., Conference). The full experiment ran for 233 days and the final results are being prepared for publication. Of great significance was the fact that remediation occurred even though concentrations of BTEX entering the barrier had increased several fold during the course of the experiment. Nevertheless, upon passing through, all of the compounds were remediated to federal standards except for benzene which was reduced 98%, dropping from 1870 ppb to 34 ppb. In some states this would be acceptable for closure. The Alaska study looked at the dispersion of oxygen in the field, with special reference to a predictive model. The field test oxygen measurements exceeded the predicted dispersion results by a factor of two to three times. The actual results were significant enough for the company to propose a full scale barrier and purchase the product for installation. In all of these studies the effectiveness of ORC was clearly demonstrated. The validity of the basic concept was proven. Oxygen can be delivered to the subsurface in a passive, low cost time release manner, which can be effective in the remediation of moderate levels of dissolved phase hydrocarbons, traversing the barrier with typical groundwater flow velocities. ORC is appropriate to be considered whenever aerobic bioremediation could be the technology of choice. The oxygen barrier concept can be used to contain a spreading groundwater plume as described. Another use of ORC is the in-situ treatment of "hot spots" to bring down contamination quickly to more acceptable levels. Or, ORC can be used as a "polishing agent"to continue remediation after a more expensive pump and treat system is turned off. Finally, ORC has been successfully demonstrated for odor control and in biopiles; particularly in remote or inclement areas that limit the viability of other treatment methods and/or where theap ssive release of oxygen in-situ offers safety or operational advantages.