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RESOLUTION NO. R5-20021181 2 WHEREAS, this liner performance evaluation identified issues that have not been resolved with respect to the applicability of single composite liners for Class H waste units at Forward Landfill; and WHEREAS, because of the following site-specific considerations with respect to the final 10 acre waste management unit (WMU D-02)within the 100 acres of area D, the threat to groundwater quality at WMU D-02 using a single composite liner with two foot of clay as it bottom component is minimal: • Class II waste management units in area D with single composite liners constructed since 1993 by Forward Inc. have a history of high quality construction, good operational practices and no evidence of a release of waste constituents to the environment; and • There is approximately forty-five (45) feet of separation between the bottom of the waste unit and groundwater, and native soils beneath the unit are intercalated clay, silt, and sand; and • Forward Inc. proposes to construct WMU D-02 with a double composite liner under the sump area, thus giving an extra level of protection in the area most likely subjected to build—up of hydraulic pressure head; and • WMU D-02 is the final 10-acre parcel filling the northeast corner of a larger previously constructed 100-acre landfill area composed of multiple, single composite lined waste management units; and • Construction of a double composite liner at this time will present unique and difficult constructability problems. Constructability problems that would have to be resolved include: matching a double liner with two existing single liners; continuity of leachate drainage pipes; and stability issues resulting from multiple geomembrain layers (which can act as failure plains)in an area exposed to lateral stresses from two directions; and • Forward Inc. has proposed to aggressively control landfill gas at the combined Forward/Austin Road landfill and has submitted a plan for landfill gas control at the Forward site; and WHEREAS, Forward Inc. will fill the currently operating waste management unit by late summer 2002 and started construction of the new unit WMU D-02 in April to avoid running out of capacity; and WHEREAS, there is insufficient time to resolve all outstanding issues with Forward's liner performance demonstration for expansion outside of the D area in time to prevent a temporary shutdown of landfill operations; Therefore,be it RESOLVED, that the California Regional Water Quality Control Board, Central Valley Region, hereby approves construction of a single composite liner for the remaining 10 acres of waste management unit D-02 provided that it otherwise complies with all the requirements of WDR Order No. 97-141 and Title 27.