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WASTE DISCHARGE REQUIREMENTS ORDER NO. R5-2014-0006 -22- FORWARD INC.AND REPUBLIC SERVICES INC. FORWARD CLASS II LANDFILL SAN JOAQUIN COUNTY is LANDFILL CLOSURE 91.Title 27, section 21090 provides the minimum prescriptive final cover components for landfills consisting of, in ascending order, the following layers: a. Two-foot soil foundation layer. b. One-foot soil low flow-hydraulic conductivity layer, less than 1 x10-6 cm/s or equal to the hydraulic conductivity of any bottom liner system. c. Geomembrane layer (this layer is required for composite-lined landfills for equivalency to bottom liner). d. One-foot soil erosion resistant/vegetative layer. 92.Title 27 allows engineered alternative final covers provided the alternative design will provide a correspondingly low flow-through rate throughout the post-closure maintenance period. 93.The Discharger submitted a December 2008, Preliminary Closure and Postclosure Maintenance Plan (Appendix L in the Joint Technical Document) for closure and post-closure maintenance of all the unlined and composite-lined landfill units at the facility. The Closure Plan proposes eight-staged closure projects over the life of the Landfill. Final closure dates for the various stages will depend on module fill rates. The first closure Stage consists of most of the top deck, north and west side-slopes of the Austin Road Unit and the east, west and south slide-slopes to a height of 150 feet of the Forward Unit. To date, the first stage areas on the Austin Road Unit have a final cover installed but not yet certified as closed. All of the first stage was tentatively scheduled for completion by December 2014. 94.Due to Forward Landfill changing development plans, the 2008, Preliminary Closure and Postclosure Maintenance Plan, is outdated and it is unlikely that the 2008 closure stages can occur as projected. This Order requires submittal of an updated Preliminary Closure and Postclosure Maintenance Plan. 95.The Discharger proposes an ET final cover for closure of the landfill. The proposed final cover consists of a minimum of one-foot of existing interim cover overlain by a minimum of three-feet of selected fine grained soil. 96.From 2006 to 2010, the Discharger completed a demonstration project for an alternative final cover system on the northern slope of the Austin Road Unit. The project involved a three- foot thick soil cover over the existing one-foot thick interim cover. The soils consisted of on- site clayey silt with an as-built minimum hydraulic conductivity of 1 X 10-6 cm/sec. Performance of the demonstration cover was monitored for climate (rainfall, evaporation, solar radiation, relative humidity, barometric pressure, temperature and wind speed) and soil moisture at various depths within the 4-feet thick cover. Lysimeters at the bottom of the cover system measured no breakthrough (no water infiltration through the cover and into the waste) over the four-year test. Soil moisture and heat dissipation sensors installed at various depths within the cover demonstrated overall soil drying trends; upward moisture and soil