|
Configuration of the landfill — A plan illustrating the configuration of the landfill is provided below. The landfill plan shows the topography of the waste accumulation area within the landfill fence boundary and the surrounding land for a distance of approximately 200 feet. The plan also shows the final configuration of the landfill at closure, including the final grade, berms, swales for proper drainage, and control of surface water run-on and run-off for the site. A typical cross-section of the landfill is oriented north-south across the center of the landfill, and shows the existing landfill surface, the final grade at closure, and the drainage controls for surface water run-on and run-off for the site.
Final Cover — The final closure design for the landfill was based on information collected during the site inspection and from site process knowledge, as stated in the Landfill Closure Plan. As detailed in that plan, the final cover will consist of 18 inches of compacted native soil with a hydraulic conductivity less than 1.0E-O5 cm/sec overlain by 6 inches of soil capable of sustaining vegetative growth. The final lift of waste under the cover will be compacted to minimize settlement, and will have a 3 percent grade. The compaction will be in accordance with specifications detailed in Appendix D of the Closure Plan.
Liner System — There is no liner system beneath the landfill. Pursuant to NAC 444.704, a liner system is not required since this is a Class II landfill. A "Request for Variance, Groundwater Monitoring and Composite Liner Requirements" is included from the 1998 Permit Application. That document provides a technical evaluation of the operation and closure activities and specifications in support of the variance request.
Leachate Collection and Removal System — The landfill was constructed without a leachate collection system. Pursuant to NAC 444.704, a leachate collection system is not required since this is a Class II landfill.
Devices for Monitoring and Controlling Landfill Gas — As mandated by NAC 444.667, the owner or operator of a municipal solid waste landfill must provide for the control of explosive gases at the facility. In accordance with this regulation, gas monitoring is performed in on-site structures and in the native soils. Landfill gas will be monitored annually during the active life of the landfill and the post-closure period. A mobile sensor and network of landfill gas monitoring wells will be used to monitor the potential migration of landfill gas from the facility.
Each well location will contain a cluster of two wells designed to monitor different intervals in the subsurface. Gas monitoring wells are monitored annually with appropriate equipment to ensure that landfill gas concentrations do not exceed the lower explosive limit (LEL) for methane at the facility boundary. Pursuant to NAC 444.667, ambient air in permanent structures at the landfill (at the metal building) are also monitored annually to ensure that landfill gas concentrations do not exceed 25 percent by volume of the LEL for methane. Monitoring data is entered into the operating record after the monitoring event.
Cover Material — The 6-inch daily soil cover and 12-inch intermediate soil cover will be constructed with soil excavated from the new landfill cells excavated north of the existing cell. Excess soil from the new cell excavations will be stockpiled at the landfill site. Soil will be taken from this stockpile to construct the final cover, consisting of an I8-inch compacted soil layer and 6-inch vegetative soil layer.
Drainage Control System — The final cover will be graded smooth, and the area around the landfill will be contoured to prevent run-on from a IOO-year storm and six-hour up-slope precipitation events. A drainage swale around the foot of the landfill cover will be constructed to control run-on and run-off.
|
