RFB-09-26 EEC-24084AMLBAML RECLAMATION PROJECT
RFB-09-26 EEC-24084AMLBAML RECLAMATION PROJECT
Estimated Length of Project:
(Substantial Completion) + 90 Calendar Days (Final Completion)
The work will consist of excavation of the spoil material around the mine subsidence area. An existing concrete structure from the original mining is visible in the subsidence depression.
Excavation will extend to the lowest elevation of the face of the existing concrete structure. Side slopes for the excavation area of 3:1 to 4:1 will be required, and benching may be necessary to provide a safe working area. Once the existing concrete structure is fully exposed, a concrete cap will be constructed to fully close the mine opening. It is unclear if the concrete structure is associated with the slope shaft or an air shaft of the Goldsberry Mine. Methane monitoring is the responsibility of the contractor, and if methane is encountered, the contractor must immediately implement a plan to secure the area. Methane monitoring and control is incidental to the overall completion of the project.
The reinforced concrete mine closure will be constructed with the following general guidelines.
Excavate a 20 ft diameter circular trench to a depth reaching the bottom of the face of the
exposed existing concrete mine structure. The excavation slopes will be at approximate 3h:1v to 4h:1v. Benching will be required if needed for stability. The concrete mine structure will be examined by the engineer and a formed reinforced concrete closure will be constructed around the opening. The concrete closure will be 8 inches thick and will have #5 reinforcing steel at 12- inch centers both ways. Form work will be required on both faces with the interior face being set 4 inches inside the existing structure. The new closure will use drilled and epoxy dowel rods to attach to the existing structure wall on 2 ft. centers. The new closure will extend 12 inches beyond the existing structure on every side.
The floor of the excavation area can be stabilized with Filter Fabric and Size 2 Coarse aggregate or roadway stone if required. Pumping will be required to keep the working area dry and is incidental to the overall completion of the project. Material excavated will be stockpiled within the project limits and will be used to backfill the pit. Upon completion of the concrete mine closure, the excavated spoils will be used to fill the subsidence area by placing in 12-inch
compacted lifts. Additional material will be found on site within the project limits to bring the elevation to existing surrounding grade. Additional filter fabric and Size 2 aggregate may be required by the engineer.
Other work includes site preparation, repair of driveways, and other features disturbed during the construction process. An on-site temporary stockpile for excavated spoil will be used, but items not suitable for disposal must be taken to a landfill. Driveways damaged during the project will be repaired in kind with bituminous pavement. Removal of existing pavement is required on driveways and is incidental to repair. Standard AML revegetation methods and best management
practices for silt control will be used. All disturbed areas will be promptly revegetated at the end of construction using lime, fertilizer, AML seed mix, and mulch, as necessary.
The project site has previously been disturbed by road construction, utility installation, mining
and business development, landowner activities, and surface expression of deep mine subsidence. These disturbances consist of significant mixing, and removal of earthen material from excavation, grading, fill material placement, road construction, site development and driveway construction. There should be no undisturbed earthen material to a depth of several
feet at the areas slated for significant project-related construction activities.
Access to the site is via state and county roads, a business-maintained driveway, and an existing access road. This construction activity will consist of standard road construction practices appropriate to mitigate impacts to the local community from potential degraded road conditions to maintain public traffic safety.
The strict implementation and enforcement of standard AML sediment and erosion control Best Management Practices (BMPs) will prevent significant amounts of sediments disturbed by project related activities from entering area streams to create indirect impacts to aquatic resources.
Project Location: Henderson