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• • Draft Supplemental Environmental Impact Report Page IV.G-20 • Forward Inc. Landfill 2018 Expansion Project • In order to minimize sediment transport to Littlejohns Creek, landfill slopes, ridgetops, and peripheral areas would be revegetated to inhibit erosion. • Implementation of these procedures would reduce the impact to a less-than-significant level. • Mitigation Measure G.2: None required. • • Impact G.3: Potential groundwater impacts could result if the proposed liners and leachate • collection systems for the Landfill expansion areas were not properly designed or installed, or if they were to fail later on. • • Without a properly designed landfill cell liner and LCRS installed in the project expansion • areas, landfill leachate could percolate through the ground underlying the landfill units and potentially contaminate groundwater. To address this potential, the expansion areas would • have a leachate collection system installed that will meet the federal and state Class 1I landfill design requirements. There have been no historical problems of note with the existing leachate • system at the landfill units and the new leachate collection system is not expected to encounter • more difficult on-the-ground conditions. • The following groundwater quality protection measures are proposed as part of the project: • • A double liner would be installed under the sump area, as previously required by the • RWQCB; • • The liner and leachate collection system for the two new expansion areas would have new a • leachate management system. The adequacy of the leachate collection system and associated • monitoring would be reviewed and approved by the RWQCB; • The regulatory required separation between the liner and groundwater shall be • implemented to allow for chemicals in the leachate to attenuate before reaching the • groundwater,should the leachate breach the liner and leachate collection system; • • Electric testing of the liner in each WMU shall be conducted before waste can be disposed in that Unit, as required by the RWQCB; • • If any modifications to the leachate collection system and associated monitoring are • required by the RWQCB, the landfill operator shall implement those changes; • • The liner system will be overlain by a protective operations layer consisting of a one-foot • thickness of soil and a one-foot thick gravel layer that serves as the leachate collection layer. This two-foot layer will serve to protect the liner system from sharp or jagged materials in • the waste. • • The operator will remove any hazardous materials spotted during delivery, thus • minimizing the potential for leachate impacts to groundwater if a break occurs in the liner or the leachate collection system. • Landfill operations and maintenance are designed with adequate lifetimes to identify and • correct any failures in the leachate collection system. • • • •