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WMU C, an approximately 4-acre Class III unit overlies the south end of Trench 4 in WMU A. Because WMU A is a Class I unit, a compacted clay dike was constructed in the end of Trench 4 to separate the hazardous WMU A wastes from the nonhazardous WMU C wastes. WMU C contains a compacted clay liner and a dendritic LCRS. Operations began in WMU C in 1984. In 1994, the northern portion of the waste in WMU C was overlain by an interface liner and blanket LCRS consisting of a geosynthetic clay liner (GCL), a 60-mil high density polyethylene (HDPE) geomembrane, and a geocomposite drainage net. This area is known as WMU D-94. Municipal solid waste and designated wastes were placed over the interface liner. Municipal solid waste was placed over the portions not underlain by an interface liner and LCRS. WMU D comprises a significant portion of the area north of the South Creek and includes several constructed WMUs. WMUs D-87, D-88 N, D-88 S, and D-89 were constructed in 1987, 1988, and 1989, respectively. All of these units met or exceeded the liner construction requirements for Class II landfills at the time they were constructed by providing at least 2-foot thick compacted clay liners. WMUs D-88 N, D-88 S, and D-89 have 4-foot thick liners. WMUs D-87, D-88 N, and D-88 S have dendritic LCRS's and D-89 has a blanket LCRS. Interface liners, as described for WMU D-94, have been placed over existing waste in WMUs D-88 N, D-88 S, and D-89 to separate municipal solid waste in these units from designated wastes that have been placed above them. WMUs D-93, D-94, D-95, D-97, D-98, D-99, D-00, D-01, and D-02 are permitted to receive designated wastes. These units were constructed to meet prescriptive Class II regulatory requirements for base liners and LCRS' and contain the following elements, listed from bottom to top: • Minimum 2-foot thick compacted clay liner with a maximum permeability of 1 x 10-7 cm/sec and/or a GCL; • 60-mil HDPE geomembrane; • Blanket LCRS consisting of a minimum 1-foot thick layer of granular drainage material (overlain by a geotextile filter) and/or a geocomposite drainage net and a network of pipes and sumps; and • Minimum 1-foot thick protective operations layer. Forward Landfill-Project Description 4-2 BRYAN A.STIRRAT&ASSOCIATES (J:\Allied\Forward\2007.0018 Lateral Expansion\Reports\Prof Descrip\021308 Final Proj Des\Sec 4.doc:2/13/2008)