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Jenny Salinas - 2 - 5 July 2021 <br /> Jacobs representatives have discussed the need for a robust background analysis to <br /> better understand if upgradient nitrate sources are present and impacting groundwater <br /> underneath the Site. Background determination discussions are ongoing. <br /> The Work Plan proposes a soil assessment consistent with prior 5-year interval project <br /> evaluations. Specifically, <br /> 1. Collect soil samples from five sampling zones: two in the former bagging plant <br /> area, and one each in the test grove, turnaround area, and north of the <br /> warehouse. <br /> 2. Sample each of the five areas from eight boring locations within a 35-foot <br /> diameter area. Samples will be collected from each boring location at 0-2 feet <br /> below the ground surface (bgs), 2-4 feet bgs, and 4-6 feet bgs intervals. <br /> 3. Composite the eight samples corresponding to each depth interval in each <br /> sampling zone. The resulting composite samples will be analyzed for nitrogen as <br /> nitrate, total Kjeldahl nitrogen (TKN), nitrogen as ammonia, exchangeable <br /> ammonium, soluble ammonia and ammonium, and pH. <br /> 4. Submit findings in an investigation report and compare results to previous 5-year <br /> composite sampling results. <br /> Central Valley Water Board staff finds the Work Plan to be consistent with historical <br /> project evaluations and concur with the scope of work. Please complete the work and <br /> submit an investigation report by 30 September 2021. Please notify Central Valley <br /> Water Board staff at least 48 hours before any sampling event so staff may be present, <br /> if desired. <br /> If you have any questions, you may contact me on my mobile telephone, if previously <br /> provided to you, or by email at Jeff.Tierney@waterboards.ca.gov. I am teleworking and <br /> will not be accessible at my desk phone, (916) 464-4680, until further notice. <br /> Jeff Digitally signed <br /> by Jeff Tierney <br /> Date:2021.07.02 <br /> Tierney <br /> 1,0:17:05-07'00' <br /> JEFF TIERNEY, E.I.T. <br /> Federal and Private Sites Cleanup Unit HALO 01 <br /> CAs <br /> Digitally signed by <br /> Nathan Casebeer <br /> Date:2021.07.02 16:53:21 8359 <br /> -07'00' <br /> k <br /> Nathan Casebeer, P.G. <br /> Federal and Private Sites Cleanup, Chief G� <br /> cc: Abe Northrop, Jacobs Inc., Portage MI <br /> Michael Kith, San Joaquin County Environmental Health Dept., Stockton <br />