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23 SAMPLE AND ANALYTICAL FREQUENCY REDUCTION <br /> CRA reviewed the groundwater monitoring program for this site in light of the State <br /> Water Resources Control Board Resolution 2009-0042 adopted May 19, 2009 and the San <br /> Joaquin County Environmental Health (EHD) July 17, 2009 letter requesting sample <br /> frequency reductions to determine the appropriate monitoring frequency and analytical <br /> suite for all wells associated with this site. <br /> We prepared Table 1, Sample and Analytical Frequency Reductions, to summarize the <br /> current groundwater monitoring program and the proposed changes to the <br /> groundwater monitoring program for this site. The justifications for changes made to <br /> each well are noted on the table. <br /> Overall most wells that were sampled quarterly have been changed to a semi-annual or <br /> annual sampling frequency. Some wells will remain on a quarterly schedule because <br /> they are source area wells and because they are located where we are planning to <br /> perform ISCO remediation, and more frequent data from these wells is useful in the <br /> planning process. <br /> f Since ethanol and methanol have not been detected in at least four years in any of the <br /> wells, we propose eliminating analysis for these two compounds. <br /> i <br /> We propose that annual sampling be performed during the second quarter of each year, <br /> and that semi-annual sampling be performed during the second and fourth quarters of <br /> each year. <br /> We will implement these proposed groundwater monitoring program changes upon <br /> approval from EHD. <br />' 1 <br /> j ; 240183 (10) 3 CGNESTGGA-ROVERS & ASSOCIATES <br /> I <br />