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v The LCRSs are tested annually to demonstrate operation in conformance with the WDRs. The results of these tests are reported to the RWQCB and include comparison with earlier tests made under comparable conditions. A leak detection system is also located under the sumps (vadose zone) in the WMUs. The leak detection system consists of either porous suction cup or pan lysimeters. The lysimeters are sampled and tested in accordance with the site's WDRs. The chemistry of the LCRS fluids will be compared with groundwater and subdrain liquid chemistry to evaluate whether a leak has occurred. Recognizing that technical discussions with the CVRWQCB have indicated that a double composite liner could be regarded as the most appropriate liner system for some landfill locations, a cost comparison was developed for the Forward Landfill to identify the additional costs that would likely be accrued for installation of a second composite liner. As indicated below, based on current manufacturing, shipping, handling, installation and CQA costs, it is estimated that inclusion of a second composite liner including clay, FML and a leak detection layer would add as much as $10,000,000 to the long-term cost of the prof ect. Since the technical discussions presented above in Sections 1 through 6 strongly indicate that the long-term performance of a single composite liner at the Forward Landfill is fully protective of water quality in the vicinity of the site, the addition of a double composite liner (with associated costs) would yield virtually no additional groundwater protection benefit. 8.0 CONCLUSION The studies that were performed for this project demonstrate that landfill leachate will not impact groundwater at the Forward Landfill. This conclusion is supported by site conditions that mitigate this possibility, and recent scientific research of lined landfills. Specifically, recent research confirms that well-designed modern landfills do provide adequate protection against water quality impairment (Giroud, Badu-Tweneboah & Bonaparte, 1992; Bonaparte & Gross, 1990). In the 1990 study, Bonaparte & Gross presented the results of a field study in which the authors investigated the quantity and origins of flow in the leachate collection systems of 30 existing lined landfills. This research confirmed that modern landfills result in negligible pollutant discharges to ISgroundwater and the more recent research determined that even a prior study by Giroud -18- C:\2000-008\Forward Composite Liner V3 .doc\09119/02 Geologic Associates Unit Cost Units Estimated Cost FML $0.601 4,356,000 ft $2,610,000 CCL $10/ d 325,000 d $3,250,000 Leak Detection Layer $0.55/ 4,356,000 ft $2,396,000 C A $10,000/acre 100 acres $1,000,000 Total Incremental Cost Est. $9,250,000 Since the technical discussions presented above in Sections 1 through 6 strongly indicate that the long-term performance of a single composite liner at the Forward Landfill is fully protective of water quality in the vicinity of the site, the addition of a double composite liner (with associated costs) would yield virtually no additional groundwater protection benefit. 8.0 CONCLUSION The studies that were performed for this project demonstrate that landfill leachate will not impact groundwater at the Forward Landfill. This conclusion is supported by site conditions that mitigate this possibility, and recent scientific research of lined landfills. Specifically, recent research confirms that well-designed modern landfills do provide adequate protection against water quality impairment (Giroud, Badu-Tweneboah & Bonaparte, 1992; Bonaparte & Gross, 1990). In the 1990 study, Bonaparte & Gross presented the results of a field study in which the authors investigated the quantity and origins of flow in the leachate collection systems of 30 existing lined landfills. This research confirmed that modern landfills result in negligible pollutant discharges to ISgroundwater and the more recent research determined that even a prior study by Giroud -18- C:\2000-008\Forward Composite Liner V3 .doc\09119/02 Geologic Associates