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31 October 2011 AGE-NC Project No. 99-0682 Page 5of9 of soil. Theoretically, the radius of influence of the injection points should increase rapidly at first, then gradually decline as the affected volume increases and the ORC-advanced ® media encounters decreasing hydrocarbon concentrations toward the margins of the hydrocarbon plume. Shorter-chain hydrocarbons are typically consumed first and longer- chain hydrocarbons later. ORC is considered to be a moderately favorable alternative to ozone sparging. However, ORC does not appear to be the best available technology based on the following. • Remediation at sites with similar soil compositions and hydrocarbon-impact typically takes between 24 and 48 months. • Adsorbed and dissolved concentrations at the site would generally require an initial dose of a stronger oxidant to reduce concentrations to levels where ORC can treat the plumes. • A large number of borings and several treatments would likely need to be performed to achieve cleanup goals. • Additional monitoring costs would be incurred to track the progress of the injections, driving up the overall cost to complete the project. 3.3. PHYSICAL/MECHANICAL TREATMENT AGE has evaluated two physical/mechanical treatment alternatives for the site, dual phase extraction and ground water extraction. The presence of dissolved hydrocarbons at the site would require treatment of any recoverable ground water. Two of the most common methods of water treatment are air stripping and carbon adsorption. Air stripping involves removal of volatile organic compounds from ground water by promoting the transfer of contaminants from the dissolved phase to the vapor phase. The process usually works well with volatile organic compounds, but less successfully with longer-chained hydrocarbons. Carbon adsorption utilizes granular activated carbon to simply"filter" organic compounds out of ground water. A third, but less common method of above-ground treatment of water is bioremediation. Contaminated ground water is "treated" by adding hydrocarbon-degrading microbes or by augmenting natural hydrocarbon degradation activities with the introduction of nutrients. Advanced GeoEnvironmcntal,Inc.