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' Qealogical 7-ech4la kc. Page 4 Sinclair Trucking Feasibility Study Project No. t030.3 June 25,2003 • Alkalinity of the contaminated zone was enriched compared to background. This may ' be secondary evidence of aerobic biodegradation activity. • Nitrate of the contaminated zone was depleted compared to background. • Oxidation-reduction potential of the contaminated zone is lower compared to ' background. • The measured pH in the water table wells range between 7.3 and 7.6. This pH range is conducive to�!_pinta nvngiaerolbibiodegradationI ' • Temperature is slightly elevated in the impacted area. 2.4 In Situ Remediation ' In situ remedial systems are processes that treat the groundwater in place rather then removing it to the surface and treating it above ground. ' Advanced Oxidation Processes AOPs Advanced oxidation processes (AOPs) are processes that create and use a highly reactive radical that effectively oxidize MTBE and other organic compounds by chemical reaction. The most prominently used radical is the hydroxyl radical, designated as OH. The OH ion will capture a hydrogen atom from a molecule of contaminant, which then causes the contaminant molecule to become unstable and breakdown further. The end products of this breakdown process are reported to be bicarbonate, water and small amounts of mineral acid from any halogen, nitrogen or sulfur present in the groundwater. ' The AOPs have been very successful at treating gasoline compounds and the gasoline oxygenated fuel compounds. AOPs are promising because they quickly destroy the contaminant rather then augmenting the relatively slow biological processes at the site. Typically, AOPs use one or more of the following to create the hydroxyl radical: ' • peroxide • ozone ' • Fenton's reagent Oxygen Releasing Compounds ORCs Oxygen Release Compound (ORC) has been shown to aid in the natural attenuation ' degradation of petroleum hydrocarbons in the soil and groundwater. ORCs could be used at this site relatively quickly and the installation process would be relatively inexpensive. ' ORCs are magnesium peroxide compounds that slowly releases oxygen once it is hydrated. The byproducts of the reaction are oxygen and magnesium hydroxide. The material continues to release oxygen in the subsurface for approximately 6 months after application. ' The ORCs are installed using a GeoProbe direct push rig and a pressure pump. A series of - borings are pushed to a determined depth then a slurry of ORC is pumped through the drill rods under pressure as the rods are retrieved from the boring. The borings are drilled in a ' grid pattern in the area of highest groundwater contamination. The application and cost of ORC and an AOP are very similar, however the AOP has the advantage because it is directly breaking down the contaminant where the ORC is only