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Joe Niland - 2 - 25 August 2021 <br /> Geosyntec proposes to implement focused SVE in the vicinity of soil vapor probe SG-100. <br /> Two SVE wells will be installed near SG-100, one screened between 5 and 10 feet below <br /> ground surface (bgs) and the other screened between 10 and 20 feet bgs with the <br /> assumption that each will have a radius of influence (ROI) of 50 to 100 feet based on <br /> previous SVE data for the Site. The locations of the proposed SVE wells are shown on <br /> Figure 3 of the Remedial Plan. <br /> Geosyntec will use a mobile trailer mounted SVE system powered by a generator to <br /> extract soil vapor and granular activated carbon vessels to treat the extracted soil vapor. <br /> Initially, a pilot test will be conducted to assess ROI and to optimize SVE operation. The <br /> pilot test will be limited to a five-day period to utilize a pilot testing permit exemption. After <br /> the initial five-day pilot test, Geosyntec will demobilize the SVE system, and collect <br /> performance monitoring samples from SG-100 and the two adjacent SVE wells to evaluate <br /> the potential for rebound in PCE soil vapor concentrations. Performance monitoring <br /> samples will be collected one-, three-, and six-months following implementation of the pilot <br /> testing. Additional confirmation samples may be collected if the data will be valuable in <br /> establishing trends and to assess rebound. The rate of rebound in soil vapor <br /> concentrations will determine how many sampling events are needed and whether <br /> additional SVE activities are necessary. <br /> Geosyntec will submit performance assessment reports after the one-month and six-month <br /> sampling events. Geosyntec will include an assessment of whether additional SVE is <br /> needed in the six-month report. Consideration for the proposed ISCO for groundwater will <br /> be assessed after all SVE activities have been completed. <br /> Central Valley Water Board staff concurs with the SVE pilot testing and performance <br /> monitoring. Therefore, by 7 January 2022, please submit the first performance <br /> assessment report and by 3 June 2022, submit the second performance monitoring report <br /> that includes an assessment of the data and recommendations. The five-day pilot testing <br /> exemption shall be confirmed with the San Joaquin Valley Air Pollution Control District <br /> prior to the proposed SVE pilot testing. Please provide us with at least 72 hours' notice <br /> prior to initiation of the any field work so that we have an opportunity to observe the work. <br /> Feel free to contact me with any questions or concerns regarding this letter at <br /> (916) 464-4622 or Bill.BrattainCd�waterboards.ca.gov. <br /> �pQaoFesAID <br /> °'gitallysignedbyWilliamBrattain �}y�p 3LQ. <br /> William Bratfie� FLo <br /> bate:2021.08.25 13:41:46-07'00' y+ rL\ <br /> William Brattain, P.E. c62154 <br /> Water Resource Control Engineer * /* <br /> Private Sites Cleanup Unit OF 08/25/2021 <br /> Kristin �, Digitally signed by <br /> ��_ Kristin Shelton qj�oFesat° <br /> Shelton Date:2021.08.26 ,Y9t"AA,SAI .� <br /> 08:58:04-07'00' <br /> Kristi Shelton, P.E. C74503 <br /> Senior Water Resource Control Engineer * <br /> Private Sites Cleanup Unit °Mr,..► <br /> OF <br /> cc: Srinivasa Varadhan, PE, Geosyntec Consultants, Inc., Rancho Cordova <br />