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30 January 2014 <br /> AGE Project No . 99-0682 <br /> Page 17 of 28 <br /> longer-chained hydrocarbons . Carbon adsorption utilizes granular activated carbon to <br /> simply "filter" organic compounds out of ground water. A third , but less common method <br /> of above-ground treatment of water is bioremediation . Contaminated groundwater is <br /> "treated" by adding hydrocarbon-degrading microbes or by augmenting natural <br /> hydrocarbon degradation activities with the introduction of nutrients . <br /> 11 . 1 .2 . Feasibility <br /> Groundwater extraction pumping tests have not been completed for the Stallworth Auto <br /> Sales site . Also , groundwater extraction and treatment would not treat hydrocarbon <br /> impacted soils in saturated zones at the site, and additional treatment methods would have <br /> to be coupled with the technology to address these areas. <br /> There are several other disadvantages to "pump and treat" methods. The most serious <br /> disadvantages include: 1 ) extended cleanup periods, resulting in increased total costs , <br /> although the maintenance for this method is relatively cost-effective and 2) regulatory <br /> cleanup goals are rarely attainable , mostly due to persistent hydrocarbons detected during <br /> subsequent sampling events . Groundwater extraction is generally not a desirable method <br /> for remediation , however this technology is useful for hydraulic control to prevent spreading <br /> of the contaminant plume . <br /> Based on the evaluation of the technology provided above, groundwater extraction does <br /> not appear to be the most feasible option for treatment of the on-site groundwater and <br /> "drowned" adsorbed plumes . <br /> 11 . 1 . 3. Duration <br /> Based on AGE's experience, groundwater extraction systems typically require several <br /> years in order to remove a bulk of the contaminants dissolved within groundwater. Based <br /> upon the groundwater plume size and the general lithology beneath the site , it appears that <br /> a 24 to 36-month period would be required to effectively remediate impacted groundwater <br /> at the site. <br /> 11 . 1 .4 . Estimated Cost <br /> Costs for installation of a "pump and treat" groundwater remediation system typically <br /> ranges from $80 , 000 to $100 , 000 , including the installation of large-diameter extraction <br /> wells . The approximate cost to operate, sustain , monitor and sample a groundwater <br /> extraction remediation system could vary from $75 ,000 .00 to $ 100 , 000 . 00 per year. <br /> Advanced GcoEnvironmental, Inc. <br />