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8 LFR <br /> from and within the sands (referred to by FA as the Eastern Hot Spot), and any adjoining clays or <br /> silts, will then decrease over time and will be captured and remediated by the extraction system, <br /> which is located downgradient from the sparging system. <br /> FA Comment 2: <br /> Much time has passed since LFR's original Draft Feasibility Study was produced May 5, 2000. <br /> Significant advancements have occurred in remediation technology over the past six years, and <br /> more emphasis has been placed on remediation to mitigate vapor migration and the potential for <br /> inhalation exposure. It is important to address these issues when updating and revising the Draft <br /> Feasibility Study. In addition, the time frames required to complete site remediation under various <br /> remedial alternatives need to be estimated and given due consideration when comparing the <br /> effectiveness of remedial alternatives. This was one of the important comments Farr Associates <br /> made previously in response to our review of the Draft Feasibility Study and the Revised Draft <br /> Feasibility Study reports. <br /> Finally, considering that the Site Remedial Investigation Report was completed December 10, <br /> 1999, and the first Draft Feasibility Study was completed May 5, 2000, it is very important that <br /> LCERT complete the feasibility study process and select the final site remedy in the near future. <br /> The progress on evaluation of potential remedial technologies and remedial alternatives for the Site <br /> has been unreasonably slow, and LPL needs to see this process concluded as soon as practicable. <br /> Response to Comment 2: <br /> LFR has been aware of the inhalation issue since early in 1997 when remedial investigations <br /> indicated the potential for inhalation risks within the HSA at the Site. This concern precipitated the <br /> expedited installation of the existing soil-vapor extraction system prior to 2000. LFR understands <br /> that Lincoln has since performed vapor sampling within its buildings and found that vapor <br /> exposures from subsurface chemical migration are not occurring within its buildings. Additionally, <br /> as documented in LFR's RI/FS report dated December 10, 1999, surface areas located over the <br /> groundwater plume, which are lateral to the HSA, never showed any shallow soil vapor or indoor <br /> air issues resulting from volatilization of the underlying VOC-affected groundwater. Thus, the <br /> requested emphasis on "remediation to mitigate vapor migration and the potential for inhalation <br /> exposure" has been implemented and will continue to be part of our focused remedial plan for the <br /> Site, as will groundwater remediation. Again, these data have all been incorporated within the <br /> SCM, which shows no indoor air issues away from the source areas. <br /> Once the air/ozone sparging system is in place and the investigation in the vicinity of MW-108A <br /> (i.e., the Bank of Stockton area) is complete, the FS will be finalized and the final remedy can be <br /> selected. To date, the series of pilot tests requested by FA within the HSA prior to finalization of <br /> the FS has been completed, and additional investigations and pilot studies are being proposed in the <br /> Bank of Stockton area. Considerations regarding time frames to achieve remediation goals will also <br /> I[r-Farr-FS-response-06750.dm:lfr 5 <br />