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i • 6.3 Proposed Groundwater Air Sparging System ASE proposes installing an in-situ air sparging (AS) system for remediation of dissolved and separate-phase petroleum groundwater contamination on the subject property The AS system will infect clean compressed air below the impacted groundwater surface at approximately 17 to 19-feet bgs through seven (7) AS wells to strip petroleum contamination from the groundwater and soil The AS system will also increase the dissolved oxygen levels in the groundwater which will enhance natural biodegradation of gasoline and diesel in the impacted groundwater a n d soil The proposed AS system will depend on the soil vapor extraction system to remove all volatile gasoline compounds stripped from the groundwater Generally, the total soil gas extraction rate should be at least 150 percent of the total air sparging flow to prevent the possible spread of contamination through the release of fugitive gasoline vapor-laden air Additionally, the zone of influence of each air sparging well must be within the calculated radius of influence of the vapor extraction wells in order to ensure capture of all gasoline vapor-laden air Figure 7 depicts the proposed configuration for air sparging and vapor extraction wells 6 3 1 Aar Sparging Flow and Pressure Controls Individual buried 112 inch diameter air-hose lines will connect each AS point to the AS control panel (Figure 7) The control panel will be used t o regulate and measure compressed air flow to the AS points A blower- type pump (Roots or similar) capable of a total air sparge flow rate of approximately 100 cfm at a pressure of approximately 20 pounds per square inch (psi) will be powered by the IC engine The flow rate will depend on the extraction rate of the VE wells and system Since it is driven by a PTO unit off of the IC engine, the air sparge blower will automatically shut down when the IC engine shuts down, thereby preventing the infection of air into the groundwater when the vapor extraction and thermal oxidation system is not operating 6-4 Additional VEIAS System Construction Details Note that the proposed AS/VE system does not require electrical power unless an electric air compressor is substituted for the blower-type air sparging pump The IC engine will require supplemental fuel in the form of portable liquid propane Frank's One Stop Remedial Action Plan — August 2001 -21-