The U.S. Bureau of Land Management’s (BLM) Idaho Falls District has released a draft environmental impact statement (EIS) analyzing a mine and reclamation plan that P4 Productions LLC, a subsidiary of Bayer, formerly Monsanto, submitted for a proposed Caldwell Canyon Mine in southeastern Idaho’s Caribou County.
P4 has proposed a plan to develop several phosphate leases that the company owns on Schmidt Ridge, about 13 miles northeast of Soda Springs, Idaho, including modifying leases to add about 656 acres needed to achieve maximum ore recovery. The BLM and other agencies cooperating on the draft EIS are seeking public input to ensure that all aspects of the proposed action have been thoroughly analyzed.
In total, the mining and support facilities would disturb about 1,559 acres – 153 acres of BLM public land, seven acres of previously disturbed U.S. Forest Service land, 230 acres of Idaho State Endowment land, and 1,169 acres of private land. The expected mine life would be about 40 years, followed by an expected two years of reclamation.
P4 would use mining methods at the Caldwell Canyon Mine similar to those used at the Blackfoot Bridge Mine, and would begin in time to transition from the Blackfoot Bridge Mine when it is depleted. Blackfoot Bridge, near the Blackfoot River, has an estimated 11 years of phosphate ore left.
The proposed Caldwell Canyon project consists of developing two new open mine pits; construction of haul and access roads; installation of a power line, water management features, monitoring wells, and shop and office facilities; implementation of environmental protection measures; and reclamation. Ore would be sequentially removed from the north and south pits in 10 phases lasting three to six years each.
The preferred alternative for Caldwell Canyon includes use of an earthen cover, combined with a geo-synthetic cover, over selected portions of mine waste rock to meet water quality standards. Ore would be hauled via truck to an existing railroad load out and then by rail to Bayer’s elemental phosphorus processing plant in Soda Springs. Mine overburden would be placed as backfill in the mined out Dry Valley Mine pit and the Caldwell Canyon pits as they are mined out.
Mining below the water table would occur at the south and north ends of a pit where ground water interception wells would be installed to draw down levels below the planned pit bottom to reduce water flowing into the pit. The water would be stored in ponds. With the exception of a culverted haul road crossing, P4 proposes to avoid Caldwell Creek, a non-fish-bearing stream between two pits. An earthen cap would reduce precipitation infiltrating into pits.
The preferred alternative analyzed in the EIS seeks a balance between resource extraction and conservation, while providing opportunities for high-paying jobs in the local community. If approved, the Caldwell Canyon Mine would sustain about 185 mining jobs and 585 plant jobs for an additional 40 years, and would aid the region by providing $49 million annually in payroll, taxes, royalties, and purchases, as well as sustaining support and service jobs.
Cooperating agencies are the U.S. Army Corps of Engineers, Idaho Department of Environmental Quality, Idaho Department of State Lands, and Idaho Office of Energy and Mineral Resources. Due to the small amount of national forest system land impacted by the project, the Forest Service has decided not to participate as a cooperating agency, but BLM will solicit input from the Forest Service, Shoshone-Bannock Tribes, Idaho Department of Fish & Game, and U.S. Fish & Wildlife Service.
The BLM will make decisions related to approval of the Caldwell Canyon Mine and reclamation plan and/or alternatives, enlargement of the existing leases, and issuance of authorizations for infrastructure. Public meetings will be in Pocatello on Dec. 18 and Soda Springs on Dec. 19. Written comments must be submitted by Jan. 14.
