Filed with BLM Office
Reclamation measures for Cyprus (now called Phelps Dodge) Sierrita Corporation's copper mining operations at the Sierrita mine in Green Valley, Arizona were developed in accordance with the Arizona Mined Land Reclamation Act (A.R.S. 27-901). These measures will be implemented within two years of closure.
POST-MINING LAND USE
The post-mining land use objective for the portions of the facility on BLM lands is wildlife habitat/dispersed recreation, with the exception of the open pits. These areas have stable slopes, available growth medium, and meet public safety requirements. The emphasis of revegetation efforts in these areas is the development of habitat for mule deer and other native species which now occur on or adjacent to the Cyprus Sierrita property. The goal of the revegetation plan for wildlife habitat is to provide a diverse vegetative cover that retains soils and encourages wildlife habitat establishment. The revegetation plan for wildlife habitat was developed using Best Management Practices. The revegetation plan is specific to region, taking into consideration the mean annual precipitation, desert temperatures, and existing vegetative communities which occur in the area.
Along with the development of wildlife habitat, opportunities for dispersed recreation are also created. Existing dispersed recreational activities in the area include hiking, rock collecting, wildlife observation, and deer, javelina, dove, and quail hunting. The dispersed recreation objective will be achieved by promoting wildlife habitat and by providing post-mining public access to these areas.
Reclamation measures for the open pits consist of public safety measures undertaken to reduce or eliminate potential public safety hazards. Scrap metal, wood, trash, ad other debris incidental to mining activities and reclamation activities that pose a threat to public safety or creates a public nuisance will be disposed of in the onsite-landfill, or, where appropriate, transported for proper disposal.
Barriers will be constructed to restrict public access to the pits. Six-foot high berms will be constructed around all open pits in conjunction with final mining activities. Standard 4-strand barbed wire safety fences meeting ADOT design criteria will be constructed around the perimeter of the open pits. Berms and fences will be monitored on a routine basis until all reclamation activities are completed to ensure that access to all open pits is prohibited.
Visible warning signs will be posted at 300-foot intervals around the perimeter of the pits and in other visible areas where public access is available. The signs will be constructed of weather-resistant material.
WASTE ROCK DISPOSAL AREAS
The waste rock is comprised of several rock types, including ruby star quartz monzonite, ox
Diversion ditches or retention basins will be retained to divert stormwater run-on from reaching the disposal areas. The surface of the disposal areas will be regraded, but not compacted, to minimize ponding, redirect surface flows, and to provide the final desired slope configuration. Twenty percent of the top surface of the waste rock disposal facilities will be capped and revegetated to encourage natural revegetation on the top surface and slopes.
HEAP LEACH DUMPS
Slope stability analyses were performed on three slopes selected to provide the "worst-case scenario" in terms of pile height and slope. The analyses indicate that the pile slopes are stable against circular or irregular surface failures in both the static and seismic (pseudo-static) conditions. The analysis recommended grooming the surface by crown-chaining to remove any loose surface materials (such as large boulders and cobbles) that may become dislodged. The heap leach will be neutralized during closure in accordance with APP requirements.
Stormwater diversions will remain in place to minimize stormwater run-on to the heap leach facilities. The surface of the heap leach areas will be regraded to provide a constant one percent slope to a central evaporation pond. The pond area will be compacted, and lined with six to 12 inches of growth medium. Twenty percent of the top surface of the heap leach facilities will be capped and revegetated in a mosaic pattern to encourage natural revegetation on the top surface and slopes. The existing leachate monitoring and control system will be continued in accordance with the APP.
Reclamation of the roads will promote stability, provide drainage, and encourage revegetation success to achieve the PMLU of wildlife habitat. The access roads to be reclaimed will be regraded to minimize cut banks and to promote proper drainage, if necessary. After grading is complete, ripping will be performed on former road surfaces to a depth ranging nom six inches to two feet to reduce compaction and to prepare the seedbed. The prepared roadbeds will be revegetated as described below.
Revegetation for wildlife habitat will promote the establishment of diverse and self-sustaining plant communities. The emphasis of revegetation efforts in these areas is the development of habitat for mule deer and other native species which now occur on or adjacent to the Cyprus Sierrita property. The goal of the revegetation plan for wildlife habitat is to provide a diverse vegetative cover that encourages soil retention and wildlife habitat establishment.
Revegetation will be accomplished through seedbed preparation and mechanical broadcast seeding. Growth medium will be redistributed along 20 percent of the tops of the waste rock and heap leach areas to provide a base for revegetation to facilitate plant community development.
Pure live seed will be dispersed using a mechanical broadcast seeder followed by watering (conducted using a water truck or waterpull). Natural colonization will supplement the revegetation efforts to promote long-term habitat productivity for the revegetated areas. Site preparation will occur in the fall, immediately prior to planting. Seeding will occur in late October or early November with plant growth occuring in the spring when temperature and moisture conditions are optimal.
A seed mix was recommended by the BLM, Phoenix District Office, and developed by the Natural Resources Conservation Council to promote a plant community similar to that found in adjacent undisturbed areas. Another seed mix, developed by Curtis & Curtis Seed Company, provides an alternative plant combination well suited for Cyprus Sierrita's climatic and topographic conditions. These seed mixes serve as guidelines for the revegetation plant community. However, final plant selection will occur at closure and will be based on availability, success rates, and cost. Seed types, amounts, and costs are provided in the attached table.
Periodic inspections of the revegetation efforts will occur for approximately two years during the establishment of the seedlings as part of the ongoing reclamation maintenance, or until reclamation at the mine is complete.
Note: The tailing pond(s) is not on the 385.42 acres owned by BLM; therefore, its "reclamation" is not included in this plan, but it will also remain "en situ" forever after.