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California Regional Water Quality Control Board <br /> Central Valley Region <br /> Winston H.Hickox Robert Schneider,Chair <br /> Secretary for Gray Davis <br /> Environmental Sacramento Main Office Governor <br /> Protection Internet Address: http://www.swrcb.ca.gov/rwqcb5 <br /> 3443 Routier Road,Suite A,Sacramento,California 95827-3003 <br /> Phone(916)255-3000•FAX(916)255-3015 <br /> 21 March 2002 <br /> Mr. Kevin Basso <br /> General Manager J-�� <br /> Forward Inc. a% <br /> 1145 West Charger Way <br /> Stockton, CA 95206 <br /> LINER PERFORMANCE APPRAISAL LEA CHA TE A TTENUA TION ANAL ISES <br /> PRESCRIPTIVE CLA YLINER,FORWARD AND AUSTIN ROAD LANDFILLS, SAN <br /> JOAQUIN COUNTY (Case No. 2209 & 2148) <br /> On 26 March 2001 Central Valley Regional Water Quality Control Board staff requested that Forward <br /> Inc. provide a demonstration that any future waste containment units fulfill the performance standards <br /> for a Class H landfill. In fulfillment of this request on 21 February 2002 Forward Inc. submitted <br /> "Leachate Attenuation Analyses Prescriptive Clay Liner, Forward Landfill". Staff has reviewed this <br /> liner performance demonstration and has the following comments: <br /> 1. The liner performance demonstration relies on natural attenuation within the compacted clay <br /> liner(CCL) to reduce VOC concentrations in leachate. The demonstration is general in scope, <br /> equally applicable to all landfill liners with two feet of CCL, and does not consider site-specific <br /> conditions. The demonstration's weakness is that it ignores data from the EPA study that <br /> demonstrates that in practice many composite liners do leak and the resultant leachate can <br /> contain significant amounts of VOCs as shown by recent sampling at Ostrom Road Landfill. <br /> 2. The demonstration assumes that the leachate VOC concentrations that escape the CCL will be <br /> low enough to be considered insignificant. However, Table 5 of the demonstration contains <br /> several "Calculated Final Concentration Values"that exceed MDLs for their respective <br /> compounds. These concentrations still pose a potential threat to groundwater escaping from the <br /> base of the liner. <br /> 3. The number and size of geomembrane defects assumed in the model seems inappropriate <br /> compared to the field data in the USEPA study. The draft document "Assessment and <br /> Recommendations for Optimal Performance of Waste Containment Systems"indicated that <br /> average monthly active-period leakage rates through primary composite liners will often be less <br /> that 19 gallons per acre per day but occasionally in excess of 94 gallons per acre per day. We <br /> calculate the flow rate through a I square centimeter defect in a geomembrane and a 2-foot thick <br /> CCL with a constant head of 12 inches to be 0.004 gallons per day. It would take 4750, 1 CM2 <br /> California Environmental Protection Agency <br /> Recycled Paper <br /> The energy challenge facing California is real. Every Californian needs to take immediate action to reduce energy consumption. <br /> For a list of simple ways you can reduce demand and cut your energy costs,see our Web-site at http://www.swrcb.ca.gov/rwqcb5 <br />