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V w GeotogicalrecknicsInc Page 9 Bioventing/Biosparging Pilot Test Work Plan Project No.770.2 June 9,2006 A second test will be conducted with air injection into the deeper well IW-101. This will test the lower permeability silty/clayey units at the site. In the above Air Force guidance -r document the authors state that 1 - 2 day tests underestimate the oxygen radius of influence and wrongly conclude that clay layer are not being addressed. The same parameters as above will be measured but in this case the sampling interval will be daily for up to three weeks. r 4.4 Effectiveness Evaluation Radius of Influence The amount of pressure necessary for demonstrating vacuum influence in soil vapor extraction technology is generally regarded as at least 0.1 inches of water ("How to Evaluate Alternative Cleanup Technologies for Underground Storage Tank Sites", USEPA, May, 1995). This value may also be used as a measure of positive pressure influence with lower positive pressures expected in silty/clayey soils (0.01 inches H2O). The radius of influence of the air injection will be estimated by comparing the changes in pressures at the three monitoring (extraction) wells sets- EW-1/101, EW-2/102 and EW-3/103, that are located at low varying distances from the injection wells. Oxygen Influence .. The objective of bioventing is to supply the subsurface with oxygen to enhance biodegradation of the petroleum hydrocarbons. The oxygen levels in contaminated soils vapor are expected to be depressed (<5%) due to the consumption of oxygen by the existing biological processes. The introduction of air (ambient air 21% oxygen) will increase the oxygen content in soil vapor and the radius of influence of the oxygen influence will be estimated by comparing the changes in concentrations at the three monitoring (extraction) — wells sets- EW-1/101, EW-2/102 and EW-3/103, that are located at varying distances from the injection wells. Carbon Dioxide (CO2) When soil microbes breakdown petroleum hydrocarbons a product of the biodegradation process is the formation of CO2. The measurement of this parameter is conducted after the air injection has stopped and the subsurface conditions allowed to stabilize. As the microbes consume the 02 and produce CO2, increases in the CO2 concentrations can be used to ..r demonstrate the radius of injection influence. The CO2 concentrations can also be used to estimate respiration rates. Once the air injection is terminated, the above parameters will be measured and the rates of oxygen consumption/carbon dioxide production estimated. r r r