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Notice of Availability of Final Environmental Impact Statement for the Proposed Blackfoot Bridge Mine, Caribou County, ID

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Information about this document as published in the Federal Register.

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Bureau of Land Management, Interior.


Notice of availability.


In accordance with the National Environmental Policy Act of 1969, the Bureau of Land Management (BLM) is announcing the availability of the Final Environmental Impact Statement (EIS) for the proposed Blackfoot Bridge Mine.


The Final EIS is now available for public review. The BLM Record of Decision will be released no sooner than 30 days after the Environmental Protection Agency publishes its Notice of Availability of the Final EIS in the Federal Register.


Copies of the Blackfoot Bridge Mine Final EIS are available in the BLM Pocatello Field Office at the following address: 4350 Cliffs Drive, Pocatello, Idaho 83204. In addition, an electronic copy of the Final EIS is available at the following Web site:​id/​st/​en/​prog/​0.html.

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Kyle Free, Bureau of Land Management, Pocatello Field Office, 4350 Cliffs Drive, Pocatello, Idaho 83204, phone (208) 478-6368, fax (208) 478-6376.

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The Final EIS was prepared to provide decision-makers and the public with an evaluation of significant environmental impacts resulting from the proposed action and from all reasonable alternatives. P4 Production, LLC (P4), a subsidiary of Monsanto Company, holds mineral leases issued by the United States, granting them exclusive rights to develop phosphate minerals in the Blackfoot Bridge area. P4 submitted a Mine and Reclamation Plan (MRP) to the BLM for the development of a phosphate mine on existing Federal leases and an application to modify these leases to increase their size. Prior to mining under the proposed MRP P4 must receive BLM approval and obtain additional Federal and state permits.

The BLM has prepared a Final EIS to evaluate effects of the Blackfoot Bridge Mine upon the human environment, including the potential effects of selenium and other contaminants associated with other phosphate mines in the region. The Final EIS also considers appropriate mitigation measures. The National Environmental Policy Act of 1969 (NEPA) requires the BLM to evaluate the MRP, considering the no action alternative and other reasonable alternatives, before issuing decisions on the development of the phosphate leases and modification of the existing leases.

The BLM is also required by the Mineral Leasing Act of 1920, as amended, and 43 CFR Part 3590, to evaluate the MRP from P4 to determine if the plan will achieve the ultimate maximum recovery of phosphate ore reserves contained within Federal Phosphate Leases I-05613 and I-013709.

The U.S. Army Corps of Engineers (USACE) is required to evaluate and respond to P4's application for a permit under Section 404 of the Clean Water Act, which is needed to implement the MRP. The USACE is informing the public of this application through a 30-day Public Notice for Application for Permit that will run concurrently with this Notice of Availability. The Final EIS provides the analysis upon which the BLM and other involved agencies can base their decisions.

The Proposed Action consists of P4's Plan to develop the Blackfoot Bridge Mine using open pit mining methods to extract phosphate ore. The ore would be hauled about 8 miles to P4's existing Soda Springs elemental phosphorus plant. The mine would consist of three separate mine pits, the North, Mid, and South Pits. Mining would begin in the Mid Pit, followed by the North Pit and then the South Pit. Mining of the North Pit and portions of the Mid Pit are predicted to extend below groundwater level and would require the mine to pump water during portions of the 17-year mine life. All overburden would either be used to backfill the mine pits or be placed in the external East Overburden Pile (EOP) or Northwest Overburden Pile (NWOP). Other mine-related facilities would include an ore stockpile, a truck loading facility, an equipment yard, a water management system, topsoil stockpiles, roads, and sediment control structures. Approximately 739 acres of surface are expected to be disturbed over the life of the project, with about 674 acres (91 percent) planned to be re-vegetated. Nine percent of the mine site would involve residual highwalls that cannot be re-vegetated. About 90 percent of the disturbance would occur on privately owned surface controlled by P4 and about 10 percent would occur on BLM managed surface lands.

As phosphate mining has developed in southeast Idaho, increasing concern for surface and groundwater contamination has led to the development of various best management practices to control potential selenium migration from the mines. Placing an impermeable or low-permeability cover over external overburden piles and pit backfilled areas is a preferred way to reduce infiltration into the materials to reduce the potential leaching of selenium into the environment.

As part of the Final EIS analysis, groundwater modeling has been used to estimate the potential effects of the proposed action on water resources in the project area. Model results indicate that the Proposed Action, as designed, has the potential to release selenium concentrations to groundwater and surface water in excess of applicable water quality standards. Alternative waste rock capping designs (Alternatives 1A and 1B) were developed to reduce the amount of water that would contact the backfilled pits and external overburden piles. This Start Printed Page 13430would reduce the volume of water containing constituents of concern that could potentially affect the quality of area groundwater and surface water and prevent the release of excessive selenium. Alternatives 1A and 1B would incorporate a layer of impermeable material called a laminated geosynthetic clay liner, or GCLL. The GCLL cover system would be comprised of the following materials (from surface to base):

  • 18 inches of topsoil;
  • 1 foot of weathered alluvium cover material;
  • 6 inches of drainage/protective layer material;
  • GCLL;
  • 6 inches of a protective sub-grade layer (weathered alluvium or other earthen material); and
  • Run of mine (ROM) overburden.

The GCLL includes a thin layer of powdered clay sandwiched between two geotextile layers. A geotextile is a sheet of material that is resistant to penetration damage. The top geotextile layer is laminated with a polyethylene geomembrane layer, providing an additional layer of protection.

Alternative 1A would cover all backfilled pits with the GCLL cover as well as 86 acres of the EOP and would cover the remaining areas with the Simple 1 cover, while Alternative 1B would cover all backfilled pits and the entire 141 acre EOP with the GCLL. While Alternatives 1A and 1B primarily address water quality issues, additional alternatives address other issues and are also considered in the Final EIS.

The Proposed Action and Alternatives 1A and 1B include a lease modification to Phosphate Lease I-05613. The amended lease modification areas occur in 4 separate parcels located on private and BLM surface. The lease modification allows for extending proposed mine facilities from the original lease areas into an additional 300 acres.

A Notice of Intent (NOI) to prepare this EIS was published in the Federal Register on February 3, 2006. Publication of the NOI in the Federal Register initiated a 56-day public scoping period for the Proposed Action that provided for acceptance of written comments. The scoping process identified concerns that included potential effects of the project on water resources; socioeconomic conditions; livestock grazing; reclamation and restoration; wildlife and vegetation; soils; threatened, endangered, and sensitive species; air quality; aesthetics; land use; visual resources; hazardous and solid wastes; tribal interests and cumulative effects.

The Notice of Availability for the Draft EIS was published in the Federal Register on August 14, 2009. A 45-day comment period on the Draft EIS was extended by 30 days, extending the comment period to November 2, 2009. Agencies, organizations, and interested parties provided comments on the Draft EIS via mail, email, and public meetings. Comments also came in the form of postcards, form letters, and comment forms. A total of 6,994 comments were received. The majority, approximately 80 percent of the comments, expressed support for the project. Comments expressing concerns about the Draft EIS largely focused on surface and groundwater quality issues and the proximity of the mine to the Blackfoot River. In developing responses to these comments, additional mitigation measures have been added to Alternatives 1A and 1B. Alternative 1A is the Agency Preferred Alternative. Primary mitigation features added to Alternatives 1A and 1B in the Final EIS include:

  • GCLL coverage over the East Overburden Pile (EOP) has been expanded from 21 acres to 86 acres for Alternative 1A and the northern portion of the EOP will be constructed of limestone instead of chert. GCLL coverage over the entire 141- acre EOP for Alternative 1B remains unchanged from the Draft EIS.
  • An Overburden Seepage Management System (OSMS) has been proposed as an addition protective measure for Alternatives 1A and 1B that would use a network of perforated pipes constructed underneath the external overburden piles for additional protection against unanticipated leakage events and during construction of the EOP. and
  • An Adaptive Management Plan for the water management system has been developed that would result in placement of dredged or fill material in areas currently containing wetlands and non-wetland waters of the U.S. only as necessary to manage runoff water.

It is currently expected that P4's existing South Rasmussen Mine will be depleted sometime in 2012. Because of operating requirements at the Soda Springs processing plant, it is necessary to bring Blackfoot Bridge Mine online in 2011. In the initial years of Blackfoot Bridge mining, a blend of ores from both South Rasmussen Mine and Blackfoot Bridge Mine would be required.

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Authority: Mineral Leasing Act of 1920, as amended and the Federal Land Policy and Management Act of 1976, as amended.

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Joe Kraayenbrink,

BLM Idaho Falls District Manager.

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[FR Doc. 2011-5497 Filed 3-10-11; 8:45 am]