Several federal agencies have recorded in the Federal Register their intent to prepare an Environmental Impact Statement (EIS) for Agrium Inc.’s newest proposed open pit mine operation in Southeast Idaho’s phosphate-rich Caribou County. The U.S. Department of the Interior, the Bureau of Land Management’s Pocatello Field Office, and the U.S. Forest Service’s Caribou-Targhee National Forest will jointly prepare an EIS to determine and analyze the effects of a proposed phosphate mine and reclamation plan on federal mineral leases held by Nu-West Mining Inc., doing business as Agrium Conda Phosphate Operations.
Agrium’s proposed mine plan includes two different mining areas separated by the historic, now inactive, Maybe Canyon Mine, parts of which are undergoing investigation and remediation through the Comprehensive, Environmental Response, and Liability Act (CERCLA), or Superfund, process.
The Husky 1-North Dry Ridge Phosphate Mine Project area is about 19 miles northeast of Soda Springs. It is anticipated that mining of the North Dry Ridge deposit will occur for about 2½ years, followed by about 11 years of mining operations on the Husky 1 deposit.
The proposed Husky 1-North Dry Ridge Mine Project would include an open pit phosphate mine, including stockpiles, temporary and permanent overburden storage areas, storm water retention ponds, and mine pit backfill areas; haul roads; equipment staging areas; and re-routing an existing national forest system road.
Agrium proposes building new facilities associated with its mining operations, including fuel storage area and dust suppression wells with water fill stands. Existing offices and shops at the nearby Dry Valley Mine also would be used.
The EIS will analyze a proposed disturbance of about 1,052 acres on private and national forest system lands – about 646 acres on three existing leases, 397 acres on requested lease modifications and special use authorizations, and about nine acres off lease on private lands.
Three existing leases contain 3,027 acres. To maximize phosphate mineral recovery, Agrium has proposed lease modifications or enlargements to both the Husky 1 and North Dry Ridge leases, totaling 470 acres. Agrium also has requested off-lease special use authorizations covering 395 additional acres to accommodate access roads, storm water retention facilities, and staging areas.
Within the disturbance area on national forest system lands, about 65 acres are in the Dry Ridge inventoried roadless area. The proposed action is consistent with the exemptions for phosphate mining within the general forest, rangeland, and grassland theme of the 2008 Idaho Roadless Rule.
The proposed mining sequence is to mine the North Dry Ridge and Husky 1 consecutively, but with some transitional overlap. Mining will begin in the North Dry Ridge area and then progress to the Husky 1 as production at North Dry Ridge slows.
The EIS will address potential impacts to water quality from dissolved metals, including selenium. Agrium has proposed to implement practices designed to reduce, eliminate, or mitigate these impacts. Suitable soil or other growth media would be salvaged from disturbed areas for use in reclamation.
Concurrent mine reclamation would include backfilling pits as mining progresses, grading slopes, capping overburden disposal areas and pit backfills, re-establishing drainages, spreading seeds, stabilizing surfaces, promoting re-vegetation, and testing and treatment for remaining contaminants. Environmental monitoring would be performed to ensure impacts do not exceed those authorized.
Issues initially identified for the proposed mining include potential effects on groundwater and surface water quantity and quality; absorption of contaminants by vegetation; loss of soil and mineral resources; changes to air quality; loss of wild