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LFR Inc. <br /> 2.0 PROPOSED ASSESSMENT AND CLOSURE OF THE SVE AND <br /> AIR/OZONE SPARGING SYSTEMS <br /> Due to the effective mass removal of both the SVE and the sparging systems, and the <br /> documented diminishing removal rates, it is recommended that both the SVE and <br /> sparging systems be assessed for closure. <br /> This report proposes a phased approach leading to closure, including assessing <br /> Hazardous Substance concentrations that remain in place in the vadose zone and within <br /> underlying sparged groundwater. Based on the results of the assessment, it will be <br /> determined whether the SVETS can be terminated and whether the sparging system has <br /> effectively removed the higher concentration of Hazardous Substances in the sparge <br /> area so that this groundwater system can also be shut down. <br /> LFR proposes the following steps to assess whether operation of the SVETS and <br /> air/ozone sparging systems can be terminated. <br /> 2.1 Phase II SVETS Assessment <br /> To better assess current conditions, LFR will collect soil-vapor samples from the <br /> SVETS influent, SVE wells, and new soil-gas monitoring points as described in the <br /> following sections. <br /> 2.1.1 Proposed SVETS Influent Soil-Gas Samples <br /> LFR will collect SVETS influent concentration data for the purpose of demonstrating <br /> system-wide de minimis to no continued removal of mass from soil vapor. Influent <br /> soil-gas samples will be collected in Summa canisters and analyzed by U.S. <br /> Environmental Protection Agency (EPA) Method TO-15. At least two samples will <br /> be collected 30 days apart for this assessment. <br /> 2.1.2 Proposed SVE Well Soil-Gas Samples <br /> The last time the individual SVE wells were sampled was in July 2005. Soil-gas <br /> samples will be collected from a selection of operating SVE wells to assess current <br /> baseline Hazardous Substance concentrations under current conditions. Groundwater <br /> sparging will be discontinued for a minimum of 72 hours prior to soil-gas sampling to <br /> assure adequate sweep and removal of any sparged vapors within the vadose zone. LFR <br /> recommends sampling wells located across the extent of the former plume dimensions <br /> (north, south, east, west, and hot spot). <br /> Page 4 pimp los=-Phll_IV IRA-AugOM6750.dm:deh <br />