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WASTE DISCHARGE REQUIREMENTS ORDER NO. R5-2003-0049 -11- FORWARD INC. AND ALLIED WASTE INDUSTRIES FOR OPERATION OF FORWARD CLASS II LANDFILL SAN JOAQUIN COUNTY 51. The Discharger adequately demonstrated that construction of a Subtitle D prescriptive standard liner on the side slopes would be unreasonable and unnecessarily burdensome when compared to the proposed engineered alternative design. The installation of 24-inches of compacted low permeability soil and gravel drainage material on side slopes will be technically difficult and would cost substantially more than the use of GCL and geocomposite drainage net respectively(the alternative design). The Discharger has demonstrated that the proposed engineered alternative is consistent with the performance goals of the prescriptive standard and affords equivalent protection against water quality impairment. 52. The leachate collection and removal system (LCRS)will consist of a 12-inch gravel layer with six-inch PVC lateral pipe and headers. The drainage layer will be installed at a minimum 2% grade with collection pipes placed on approximately 200-foot centers. Calculated peak daily leachate generation was 4,073 gallons/acre or approximately 0.0045 cubic feet per second. Daily peak head on the liner system was calculated to be approximately 1.6 inches. 53. A pan lysimeters will be installed beneath the landfill leachate sumps for the purpose of vadose zone monitoring. The proposed design for the pan lysimeters consists of, in ascending order: a prepared subgrade; a 24-inch thick, low-permeability soil layer(minimum permeability of 1 X 10-7 cm/sec) or a GCL liner; a 60-mil high density polyethylene (HDPE) geomembrane; a gravel filled pan lysimeter with access pipe; a GCL liner; a 60-mil high density polyethylene (HDPE) geomembrane; a gravel filled LCRS sump with access pipe;an 8-ounce/square yard separator geotextile; and a 12-inch thick protective cover soil operations layer. 54. Forward landfill has a vadose-zone monitoring network of twelve suction lysimeters and two pan lysimeters; the Austin Road landfill is an unlined facility and has no active vadose-zone monitoring. 55. The Discharger proposes the following construction quality assurance protocols for liner construction: a. monitor placement of drainage layer gravel with a dedicated CQA technician; b. a liner leak test over the entire base liner to be performed after installation of the gravel drainage layer and the operations layer; and c. during placement of the first layer of waste in a new unit, site personnel will monitor waste placement and will exclude materials that could threaten the liner.