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Kevin Basso - 2 - 4-627 November 2007 <br /> 3. The first year of the test section monitoring demonstrated that the alternative cover <br /> performed as modeled under dryer than normal conditions. Moisture did not percolate <br /> through the cover into the waste and likely dry season evapotranspiration exceeded wet <br /> season percolation (net negative flux). The test took place in 2006/2007 during a dry <br /> rainy season with approximately 47% of average precipitation. <br /> 4. The ACAP testing, the design modeling, the performance modeling and the test section <br /> performance results combine to demonstrate that the alternative cover should perform <br /> at least as well as a Title 27 prescriptive cover in an average precipitation year. <br /> Title 27 Section 21090(x) states in part the following: "...The RWQCB can allow any <br /> alternative final cover design that it finds will continue to isolate the waste in the Unit from <br /> precipitation and irrigation waters at least as well as would a final cover built in accordance <br /> with applicable prescriptive standards under¶(a)(1-3)." Therefore, staff finds that based on <br /> only one year of data and below normal wet season that Forward's proposed alternative cover <br /> design when constructed with the design materials and in the design climate will likely comply <br /> with Title 27 requirements. Staff looks forward to continued monitoring and study of the test <br /> section through at least one average or greater than average precipitation year. Staff <br /> anticipates that field performance testing may drive future adjustments to cover design but <br /> believes that the ET cover is a valid alternative to the prescriptive cover. <br /> Staff looks forward to working with you on the Alternative Final Cover for Forward Landfill. If <br /> you have any questions, please call me at (916) 464-4614. <br /> Ross D Atkinson <br /> Engineering Geologist <br /> Title 27 Unit <br /> cc: Robert McClellan, San Joaquin County LEA, Stockton. <br /> Gary Lass, Geologic Claremont <br /> Luis Mariscal, Geologic, Claremont <br /> Lochlin Caffey, Forward Inc. <br /> RDA;W:\stafflatkinsr\mydocuments\forward\EtcoverDemo.doc <br />