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17 February 2004 . AGE-NC Project No 96-0254 ' Page 7 of 10 6 1 1 Ground Water Treatment Methods The documented presence of dissolved hydrocarbons will require treatment for the recovered water Two of the most common methods of water treatment are air stripping and carbon adsorption Air stripping involves removal of volatile organic compounds from ground water by promoting the transfer of contaminants from the dissolved phase to the vapor phase The process usually works well with volatile organic compounds, but less successfully with longer-chained hydrocarbons, such as commonly occur in diesel fuel Carbon adsorption utilizes granular activated carbon to simply"filter" organic compounds out of ground water ' A third, but less common method of above-ground treatment of water is bioremediation Contaminated ground water is "treated" by adding hydrocarbon-degrading microbes or by ' augmenting natural hydrocarbon degradation activities with the introduction of nutrients However, MTBE is not rapidly treated by biorernedation 6 12 Feasibility Testing ' • 4n 23 May 2001,a ground water aquifer pumping test was performed at the site to assess the general ground water aquifer characteristics and to assess aquifer response to ground water extraction utilizing wells EW-1, MW-1 through MW-6 at a constant pumping rate Appendix A shows completion details for wells utilized for the pump test Purged ground water was containerized in an on-site 6,500-gallon poly tank (Baker tank) ' A four-inch diameter Grundfos submersible pump was utilized to evacuate water from the pumping well The pumping rate for the test was determined by measuring the time required to fill a 5-gallon bucket from the pumping discharge hose The static pumping test consisted of extracting ground ' water from well EW-1 at a rate of 5 gpm utilizing a 4-inch diameter submersible Grundfos Redi-flo r pump Approximately 3,600 gallons of water were removed from EW-1 during the 12-hour constant rate drawdown test Prior to initiation of the test, the depth-to-ground water was measured in the extraction well EW-1, ' and in monitoring wells,using a Solinst water level meter Well EW-1 is screened from 15 to 30 feet below surface grade (bsg) The other wells are screened from approximately 10 to 30 feet bsg The pump test utilized 7/8-inch diameter, model 3001 Solinst Levelogger pressure transducers that ' were deployed in wells EW-1, MM-1, MW-3 and MW-5 The height of the water column was measured by the datalogger at one-minute time intervals Each pressure transducer was pre- programed prior to the pumping test to log water levels at one-minute intervals For the pumping test conducted at well EW-1, the draw down data collected in observation well ' MW-1 through MW-6 were used to determine the aquifer properties Ground water levels in observation wells within twice the aquifer thickness or within 60 feet, appeared to be influenced Advanced GeoEnvironmental,Inc.