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r <br /> 27 June 1996 <br /> AGE-NC Project No. 95-0118 <br /> Page 12 of 23 <br /> 7.1.4. FEASIBILITY <br /> Generally, a vacuum of at least 1.0 inch of water is required to successfully volatilize subsurface <br /> hydrocarbons. As stated in Section 5.4., the theoretical radius of influence at 1.0 inches of water is <br /> approximately 27 feet. The soil matrix at the site is predominantly sand, therefore a moderate <br /> vacuum should yield significant flow rates. At least one additional soil vapor extraction well will <br /> be required at the Elkhorn Country Club site. <br /> A drawback of SVE is that not all contaminated zones of soil are remediated effectively or at the <br /> same rate. For instance, a sandy soil will clean-up more quickly than a silt; SVE is not usually <br /> effective in soil with a high clay content. Other drawbacks of SVE include ineffective treatment of <br /> soil lying below ground water or within the "smear''zone and ineffective treatment of longer-chain <br /> hydrocarbons (diesel). Ground water remediation would need to be conducted concurrently with <br /> =' SVE to facilitate remediation of the smear zone. <br /> ' 7.1.5. DURATION <br /> I`= Cleanup periods for soil vapor extraction typically range from 6 months to 1 year or more. Based <br /> upon the plume size and the presence of clay-rich soil, we estimate a soil.vapor extraction cleanup <br /> period of 6 to 18 months. <br /> 7.1.6: ESTIMATED COST <br /> The cost for SVE systems varies greatly, depending upon the particular system utilized for <br /> destruction of the extracted hydrocarbon vapors (thermal destruction, carbon adsorption, etc.). For <br /> the subject site,the cost to operate,maintain,monitor and sample an SVE system will likely average <br /> between $50,000 and $75,000.per year. Depending upon the manufacturer, rental/lease costs will- <br /> '" likely comprise approximately $24,000 to $36,000 per year of the total cost. <br /> Maintenance costs can vary significantly, depending upon the specific unit utilized. However, <br /> average monthly costs (including maintenance and supplemental fuel)can range from $12,000 to <br /> $30,000 annually. <br /> 7.2. EX-SITU TREATMENT OF IMPACTED SOIL <br /> Hydrocarbon-impacted soil can be excavated and treated on-site or transported off-site for disposal. <br /> On-site treatment alternatives (ex-situ) include aeration, bioremediation, vapor extraction, and <br />