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r� R W. Michael Carroll - 3 - 28 September 2005 San Joaquin County 4. There are inconsistencies between the HELP, model and actual proposed construction design. The HELP model is run using a homogeneoussoil at 48 inches depth, whereas the design calls for 1.5 feet of existing intermediate cover and 36 inches of soil placement for the ET cover. The test pad construction and maintenance should mimic the proposed design and shall demonstrate the ET cover, constructed as in the pilot study,will meet the performance goals of the prescriptive cover. The soil characteristics of the intermediate cover should be also included in the design if this layer will be part of the four-foot design. 5. Once the construction phase has commenced weekly progress report shall be provided to the Regional Board. 6. Winterizing the ET cover against erosion is very important, especially within the first year until the vegetation is established. Erosion control measures shall outlined in the CQA Plan. We are deeply concerned that the ET cover test section be adequately designed with all the necessary soils analysis, and soil specifications based on the proposed onsite soils. The thickness of the cover should be based on onsite data,not typical thickness reported in other reports. The vegetation proposed should be sustainable with the soils proposed under Foothill Landfill weather conditions. We urge the County use reports such as Interstate Technology Regulatory Council (ITRC)entitled, Technical and Regulatory Guidance for Design, Installation, and Monitoring of Alternative Final Landfill Covers, December 2003, in making sure all data needs for a design are met. We support many of the positive aspects of an ET cover over the prescriptive standard in Title 27. However,without a properly designed cover we may have to reject a proposed cover based on inadequate data or design instead of the merits of properly documented ET cover. If you have any questions,please call me at 916-464-4676 or email me at: mwhite@waterboards.ca.gov. MOLL WHITE Water Resources Control Engineer cc: Robert McClellan, San Joaquin County Environmental Health Division, Stockton Keith Kennedy, Permitting and Enforcement Division, CIWMB, Sacramento Mr. Tim Crandall, Kleinfelder, Inc., Sacramento 1 Kleinfelder,Landfill Closure Method Selection Report,Foothill Sanitary Landfill,San Joaquin County,California.