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The field parameters recorded are as follows: <br />• pH — 8.12 <br />• Specific conductivity 934.7 standard units <br />• Temperature 23.1 C <br />These field parameter readings differed from that of leachate collected at FSL, which are as <br />follows: <br />• pH — 6.75 to 6.86 <br />• Specific conductivity 4,822 to 4,237 standard units <br />• Temperature 31.8 to 28.4 C <br />These field parameters suggest that the liquid detected in lysimeter LZ -4 was not leachate. The <br />VOC laboratory testing for the LZ -4 sample was completed on August 6, 2018. As shown on <br />the attached lab report, several VOCs were detected. To confirm these initial detections of <br />VOCs, a verification sampling event will be conducted at LZ -4 within 30 days, by September 10, <br />2018. <br />Historically, it is very unusual for fluid to be extracted from any of the lysimeters from the site, <br />including the background lysimeter LZ -1. Since the secondary suction lysimeter at LZ -4 could <br />not produce appreciable fluid, it is clear that the lysimeters below the liner are not in saturated <br />soil. A comparison of the field parameters between the extracted fluid from LZ -4 and leachate <br />indicates that the fluid at LZ -4 was not leachate. Since this is the first time that a sample has <br />been collected from LZ -4 and refuse has been present in Module 1 for more than 10 years, it is <br />also unlikely that there are imperfections or other issues with the base liner of Module 1. <br />If verification testing of LZ -4 results in additional fluid extraction and if this fluid confirms the <br />initial VOC detections, a more detailed evaluation monitoring program and engineering <br />feasibility study will be conducted in accordance with Title 27. <br />If you have any questions, please contact Juan Acevedo, Engineer III, at (209) 468-3066. <br />Sincerely, <br />TAJ M. BAHADORI, PE <br />Senior Engineer <br />TMB:mf <br />N:\1 Foothill\RWQCB\Correspondence\2018-08-10 FH Lysimeter Letter.dou <br />Enclosure <br />(Via Email) Jim Stone, Deputy Director/Operations <br />Desi Reno, Integrated Waste Manager <br />Robert McClellon, Environmental Health Department <br />2 <br />