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Geological recltnics lite. Page 7 Interim Remedial Action Plan Project No.723.2 March 7,2005' final system will not be known until treatment system manufacturers bids are received and evaluated. The following parameters/requirements will be provided to manufacturers upon which to base their system designs: Anticipated vapor flow rates: 500 scfm (standard cubic feet minute) maximum, expect 200 - 300 cfm. Rationale - maximum flow during pilot test was 466 actual cfm with combined extraction from wells EW-1, VEW-1 and VEW-2; when temperature corrected this value will drop slightly for scfm since the measuring port was on pipe between vapor/water separator and thermal oxidizer(assumed temperature >100Y based on touch at this location). Anticipated vapor concentrations: 9,450 ug/1 TPH-G Rationale - average laboratory value from pilot test data. Anticipated groundwater flow rates: maximum 10 gpm Rationale - the sustained pumping rate from the three existing extraction wells was 3 gpm during the pilot test. We anticipate extraction from new deep well EW-2 (see section 3.2.1 below) at 5 gpm based on the assumed greater hydraulic conductivity of sandy soils. The combined system effluent should not exceed 10 gpm as a safety margin based on the sewer —" system capacity with existing 6" vitrified clay pipe. In addition, OMI Thames staff have informed GTI that if 15 gpm is exceeded the site will trigger a higher level of oversight and fee structure as an "industrial" class producer of wastewater. Anticipated groundwater concentrations: maximum of 270,000 ug/l TPH-G influent to dual phase system; maximum of 50,000 ug/1 to air stripper/carbon treatment system. Rationale - the maximum of 2 70,000 ug/7 TPH-G was recorded from EW-I at pilot test start after which concentrations from EW-1 declined. The lower concentrations to the air stripper/carbon treatment system are based on the fact that the water concentrations coming from the dual phase unit are reduced due to the vapor/water separator (averaged 18,667 ug/l). The water expected from new extraction well EW-2 (see section 3.2.1 below) is expected to have much lower contaminant concentrations than the shallow groundwater. The 50,000 ug/7 then represents the lower concentrations with a safety factor (2:1) added to ensure sewer discharge requirements are not exceeded (i.e. - benzene <500 ug/7 & MTBE <0.5 ug/l). Carbon adsorption capacity is a function of the carbon properties (density, surface area, etc.), contaminant concentration & chemical properties, general mineral chemistry of the water, temperature and contact time. These parameters are studied under laboratory conditions and then confirmed through field-testing to allow carbon manufacturers to produce isotherms for their units. GTI will request a carbon vessel contractor to develop an iso-therm for the subject site. They will then determine an applicable design usage rate in lbs/day to size the system based on the above soil vapor extraction rates and contaminant concentrations. The carbon system will also be subject to the USTCFP's three bid process. w v