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07 November 2004 <br /> AGE-NC Project No 96-0232 <br /> Page 7 of 11 <br /> by laboratory analysis sis of primary chemicals of concern MTBE and potential breakdown chemical <br /> by-products (i e TBA, formaldehyde, acetate, oxygen and hydrogen peroxide) <br /> 4 2 4 Feasibility <br /> It would appear that In-situ ozone sparging of dissolved MTBE in ground water at the site has a high <br /> feasibility On-site, MTBE-impacted ground water is most prevalent at depths between 15 feet and <br /> 50 feet bsg Lithology at depths between 15-25 feet and between 40-50 feet generally consisting of <br /> permeable to semi-permeable silty fine sands and fine sands, which is conducive for IOS treatment <br /> (Figure 10) <br /> Based on previous pilot studies conducted by LFR Levine-Fricke and by Kerfoot Technologies,Inc <br /> (see Appendix C),IOS was a very effective remediation tool in MTBE removal from ground water <br /> after only 5-7 weeks of operation Both LFR Levine-Fricke and by Kerfoot Technologies, Inc <br /> reported 96-99% destruction rates of MTBE after a 5-7 week duration <br /> One concern with IOS is precipitation of iron and/or manganese, which can cause clogging of <br /> sparging points Another concern with IOS is that ozone could artificially create high levels of <br /> hexavalent chromium if naturally occumng levels of total chromium are high enough Previous <br /> laboratory analysis of total chromium, iron and manganese at the site (Appendix B) indicated that <br /> iron concentrations in ground water at the site are adequate for IOS <br /> 4 2 5 Duration <br /> Ozone sparging conducted in conducive conditions generally result in rapid remediation rates At <br /> the site,we would estimate an extended remediation period of at least 6 to 18 months for remediation <br /> of MTBE-impacted ground water <br /> 4 2 6 Estimated Cost <br /> Installation of an IDS system would most hkelyrequire the installation of one to two additional IOS <br /> wells located near well MW-8, and possibly one to two addtional IAS wells located near the UST <br /> area,installation of an IOS piping system and installation of IOS equipment IOS setup costs would <br /> likely range from $25,000 to $35,000 Spargmg equipment, utility, maintenance and monitoring <br /> would range from $5,000 to $10,000 annually Based upon a treatment period of 6-18 months, the <br /> total costs would be in the range of$27,500 to $50,000 <br /> Advanced GeoEnvi ran mental,Inc <br />