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Overview-Summary
The Pahrump Landfill is located approximately 1 mile east of State Highway 160, on Mesquite Road and approximately 4 miles northeast of Pahrump town center. The landfill is on approximately 80 acres, with the active landfill footprint encompassing an area of approximately 42 acres. Adjacent land uses currently are open space, non-developed desert lands to the south and east, a rock quarry pit and closed landfill area to the north, and residential to the west.
Geologic/Groundwater Conditions
Groundwater at the site was encountered at 198 feet below ground surface during previous site investigations. The static groundwater level has been monitored at between 153 and168 feet. Groundwater recharge is from Mt. Charleston range located east of the landfill site.
Climate
Climatological Data for Pahrump, Nevada shows average annual rainfall of 4.78 inches per year. The average high month is February with average rainfall of 0.73 inches. The Pahrump area has annual evaporation rates in excess of 100 inches. The area has low humidity, is very arid and is a typical desert environment.
Final Cover
The Final Cover Configuration from bottom to top consists of 12 inch foundation layer, 24 inch screened native soil layer, and 6 inch erosion layer.
Perimeter Landfill Gas Monitoring
Nye County has documented 12 new landfill gas probe installation in Appendix 5. Monitoring of the perimeter landfill gas probes will be on a quarterly basis using appropriate monitoring equipment. Any buildings including the gate house will also be monitored for landfill gas on a quarterly basis.
Recycling
Recycling efforts at the landfill include recovery of inert materials such as asphalt, concrete and roof tile, as they are used in lieu of importing rock for roads and wet weather pads. Further recycling efforts at the landfill include metals (appliances, refrigerators, scrap metal) and tires. Typically, these materials are unloaded in designated areas by the haulers.
Closure and Post-Closure maintenance plan
The Closure and Post Closure Maintenance Plan for the Pahrump Landfill is presented herein. One of the purposes for this Closure and Post Closure Maintenance Plan is to provide the basis for a registered Civil Engineer to prepare a thorough estimate of the costs associated with the closure of the Pahrump Landfill. The estimated closure and post closure maintenance cost is necessary to determine the total Nye County Closure Fund that is necessary to provide Nevada Division of Environmental Protection with appropriate financial assurance justification and associated financial assurance mechanism.
Closure Sequencing
The Pahrump Landfill excavation and fill sequencing has been designed to maximize landfill capacity, schedule soil movement to minimize need for multiple handling, minimize landfilled area not final closed, and bring landfilled areas to final grade as soon as practical.
Final Closure
The Pahrump Landfill will implement various improvements during landfill operations and before final landfill closure. Those improvements include such items as: 1) landfill gas perimeter monitoring probe installations; 2) drainage detention basins; 3) perimeter drainage ditches; 4) access roads; and 5) site security. As a result, these items are not included in the closure cost estimate for the Pahrump Landfill.
Closure Construction
The closure construction items that are necessary to be constructed when final graded landfill areas are final covered with soil will include:
- final cover soils (12 inch interim cover/foundation layer, 24 inch screened native soil layer, and 6 inch erosion layer)
- vegetation (BLM native desert seed mix),
- landfill surface drainage ditches,
- landfill slope downdrain culverts,
- drainage erosion protection,
- top deck headwall diversion berms, and
- construction quality assurance testing and certification
Description of the various final cover soil layers is below.
Interim Cover/Foundation Layer -- This interim cover/foundation layer will be a minimum of 12 inches thick. This layer shall consist of native, unscreened soil and rock materials.
Screened Native Soil Layer -- This screened native soil layer will be a minimum of 24 inches thick.
Erosion Layer -- The erosion layer shall be capable of sustaining desert vegetation growth and provide erosion protection. There will be limited moisture conditioning and compaction of this layer
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