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31 October 2011 AGE-NC Project No. 99-0682 Page 4 of 9 as carbon dioxide and water. In applicable situations the use of bio-remediation technologies can optimize environmental conditions so that the appropriate organism can flourish and destroy contaminants. For the subject site, AGE has evaluated two applicable bio-remediation technologies, which include air sparging and Oxygen Release Compound Advanced (ORC-advanced 0 ). 3.2.1. Air Sparging In-situ air sparging (IAS) utilizes air injection to volatilize dissolved hydrocarbons and strip hydrocarbon vapor into the vadose zone, where it is generally recovered by a dedicated SVE system. Commonly, an extraction well is surrounded by specifically designed air injection (sparging) wells that are screened only within the saturated zone (i.e. below ground water). A low capacity blower (air compressor) connected to the injection wells forces air under pressure into the saturated zone, producing air channels that strip dissolved contaminants from the ground water and rise to the soil-air-water interface. Upon reaching the unsaturated zone, the volatilized hydrocarbons are drawn toward the extraction well by the subsurface air flow induced by the vacuum potential. Based on site conditions, which includes two zones of contaminant impact, air sparging is not considered to be a feasible remedial alternative. Air sparging has been discounted for several reasons which include: 1) site lithologic conditions (i.e. sands overlain by clay), 2) multi-zoned nature of the plume (contaminant impact to ground water between 20-50 feet bsg and 50 to 70 feet bsg and possible greater depths) and 3) highly impacted and wide- spread nature of the intermediate zoned plume. 3.2.2. Oxygen Release Compound Advanced ORC-advanced ® media is a patented material distributed by Regenesis Bioremediation Products of San Clemente, California. ORC-advanced ® media is typically applied using direct-injection techniques.This process requires ORC-advanced®media to be mixed with water to form an injectable slurry which is then pressure injected (using a pump) into the zone of contamination. Once in the aquifer, tiny ORC-advanced®media particles can sorb to and/or reside in the soil matrix and produce a controlled release of oxygen for periods of up to 1 year. Duration (and cost of enhanced bio-remediation is dependent on the volume of saturated soil and water to be remediated, the number of injection points/wells, the average concentrations of contaminants and nutrients, ground water gradient, and the permeability Advanced Geo Environmental,Inc.