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'.d Geological T"A cs Inc. �"� Page 11 <br /> Bioventing/Biosparging <br /> Pilot Test Work Plan <br /> Project No.770.2 <br /> June 9,2006 <br /> sand pack by using weighted bentonite chips. A surface seal will be achieved by pumping a <br /> neat cement grout (augmented with < 4% bentonite) through the hollow stem augers as they <br /> are withdrawn. The wells will be secured with locking watertight caps encased in flush <br /> V <br /> mounted traffic rated well boxes. The table below shows well construction. <br /> 5.2 Observation Wells <br /> The existing groundwater monitoring wells and potentially the new bioventing wells will be <br /> .r used during this test. <br /> 5.3 Equipment <br /> V <br /> The biosparging equipment will consist of an air compressor or blower, piping/hose to well <br /> head,pressure gauges and distribution valve. <br /> V <br /> The air injection pressure in the biosparging well must be sufficient to overcome the head <br /> pressure of the overlying water column and the capillary pressure of the subsurface soil. The <br /> flow rates will be small so that the sparging does not cause the contamination to spread. <br /> The EPA has stated that 1 PSI of injection pressure is necessary for every 2.3 feet of <br /> `r hydraulic head. (USEPA: How to Evaluate Alternative Cleanup Technologies for <br /> Underground Storage Tank Sites, May, 1995) GTI proposes installing the biosparging well <br /> screen at a depth of approximately 7 feet below the water table that is currently at -65 feet <br /> y bgs. This would require an injection pressure of 3 PSI(7 feet divided by 2.3). <br /> The pressurized air will be delivered to the subsurface through a ceramic diffuser that will <br /> introduce fine bubbles into the soil. The bubbles will form channels or preferential pathways <br /> through which the air will flow and deliver oxygen to anaerobic zones. <br /> 5.4 Biosparging Test <br /> Air will be introduced in new well AS-1 at a low pressure/flow rates as stated above. <br /> Pressure and oxygen levels will be measured in monitoring wells at periodic intervals as <br /> during the bioventing test. <br /> 5.5 Effectiveness Evaluation <br /> The radius of influence will be determined by measuring the oxygen content in well MW-5 <br /> and the other monitoring wells. If the oxygen content goes up in these surrounding wells <br /> then biosparging will be considered effective. The ultimate effectiveness test would be <br /> declining concentrations in groundwater over time. It should be noted that biosparging is <br /> much slower than other remedial techniques <br />