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WASTE DISCHARGE RRUIREMENTS ORDER NO. -11- FORWARD INC. AND ALLIED WASTE INDUSTRIES FOR OPERATION OF FORWARD CLASS II LANDFILL SAN JOAQUIN COUNTY minimum 2% grade with collection pipes placed on 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); 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 B- 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. 56. Construction will proceed only after all applicable construction quality assurance plans have been approved by Executive Officer. 57. The discharger proposed to construct two Class lI surface impoundments to contain and evaporate leachate from solid waste management units. An engineered alternative to the prescriptive liner requirements of Title 27 is proposed for the Class H Surface Impoundments. The engineered alternative consists of from the top down: a. A primary 60-mil-thick High Density Polyethylene (HDPE) geomembrane b. A geonet drainage layer, as a Leachate Collection and Removal System (LCRS) c. A secondary 60-mil-thick HDPE geomembrane and d. A GCL in place of the compacted clay liner.