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20 March 1996 <br /> AGE-NC Project No 95-0130 <br /> Page 19 of 23 <br />' 7 2 3 FEASIBILITY <br />' No aquifer testing has been performed at the site If necessary, a pump test can be performed using <br /> one of the existing ground water monitoring wells to determine aquifer and pumping characteristics <br />' at the site <br /> There are several disadvantages to "pump and treat methods" The most pronounced disadvantages <br /> include 1) extended cleanup penods, resulting in elevated total costs, although the maintenance of <br /> this method is relatively cost-effective and 2) regulatory cleanup goals are rarely attainable, mostly <br /> due to recurring hydrocarbons in subsequent sampling events Ground water extraction is generally <br /> not a desirable method for remediation <br />' 7 2 4 DURATION <br /> Experience has shown that all systems involving ground water extraction require much more time <br /> than would be anticipated from aquifer tests and calculations of ground water discharge rates, and <br /> seldom achieve regulatory goals for ground water clean-up Systems typically operate for several <br /> years During this time, pumps and other equipment may need replacement several times The primary <br /> utility of pump-and-treat systems is in preventing migration of contaminated ground water <br /> I7 2 5 ESTIMATED COST OF GROUND WATER EXTRACTION <br /> Costs for installation of a"pump and treat" at the Top Filling site could be as great $50,000, including <br /> installation of several large-diameter extraction wells However, once extracted, the contaminated <br /> water has to be treated or disposed Treatment is highly dependant upon the concentrations of <br /> I dissolved hydrocarbons in the ground water The cost per gallon could be as great as $2 00 Based <br /> upon the extraction and treatment of approximately 200,000 to 300,000 gallons of contaminated <br /> ground water, costs for the entire treatment project would likely be between $450,000 and $650,000 <br /> 7 3 IN-SITU BIOREMEDIATION/BIOENHANCEMENT <br /> 7 3 1 BASIC PRINCIPLES <br /> Bioremediation involves the introduction of hydrocarbon-degrading microbes and/or nutrients to <br /> enhance naturally-occumng bacteria, through wells into the ground water The microbes degrade <br /> hydrocarbons and spread laterally (and vertically) by migration and reproduction <br /> Hydrocarbon-degrading microbes are able to metabolize hydrocarbons and assimilate the resulting <br />