Final Donlin mine environmental statement released, but doesn’t include agency preference

The U.S. Army Corps of Engineers Alaska published a final environmental impact statement for the Donlin Gold mine Friday, but what regulators think of the complex development plan is still unclear.

Donlin Gold's proposal is for a large open-pit mine near Crooked Creek in the upper Kuskokwim River drainage. The mine would extract roughly 33 million ounces of gold over its initial 27-year life.

Substantial support infrastructure for the mine would also be built, including a 315-mile natural gas pipeline from near Beluga on the west side of Cook Inlet to the mine site to provide a fuel supply for the 227-megawatt power plant at the mine site. Donlin's plan also calls for a 30-mile access road from the Kuskokwim to the mine as well as expanding the Bethel barge dock and constructing additional fuel terminals in Dutch Harbor.

Donlin Gold estimates the mine and associated infrastructure that includes a natural gas pipeline from west Cook Inlet and fuel storage all the way in Dutch Harbor, will cost $6.7 billion based on its plan from a 2011 feasibility study.

Corps of Engineers Alaska District regulatory officials wrote in an email that the agency is still working through the Clean Water Act Section 404 analyses and will identify the least environmentally damaging practicable alternative through the culmination of the EIS process.

The agency is expected to select its preferred alternative plan and issue the subsequent record of decision for the Donlin Gold mine sometime this summer.

The alternatives identified by the Corps for the project outline the prospect of diesel fuel pipeline that could parallel the gasline to drastically reduce the need to barge additional diesel up the Kuskokwim, thereby cutting the risk of a fuel spill related to the mine.

The longer diesel pipeline would likely start at either Port MacKenzie in the Matanuska-Susitna Borough or at the Village of Tyonek on the west side of Cook Inlet and then link up with the gasline.

Another option to reduce diesel shipments that is considered in the final environmental impact statement, or EIS, is to mandate Donlin employ LNG-fueled haul trucks at the mine.

The EIS also contemplates a dry stack tailings facility instead of the more traditional tailings pond and dam. Using the dry stack method would avoid a potential tailings waste release from behind the dam, but also require a filter plant that would produce a partially saturated "compactable filter cake," according to the EIS, that would trucked to the storage facility and then be spread and compacted by bulldozers.

Donlin is proposing a 2,300-acre fully lined wet tailings storage facility.

The mine site is on lands owned by The Kuskokwim Corp. and Calista Corp., the area village and regional Native corporations, respectively.

Donlin spokesman Kurt Parkan said in addition to the record of decision the company still has to secure numerous other state and federal permits, among them approvals for water discharge, waste management and a tailings dam safety permit that will eventually require additional geotechnical drilling.

After the permits are secured company leaders will reevaluate the project's economics, which they acknowledge are subject to the volatility of gold prices, and begin the search for financing if the project pencils out.

Donlin Gold leaders acknowledge the project is more sensitive to gold prices than even other Alaska prospects simply because of its associated infrastructure costs.

Elwood Brehmer can be reached at elwood.brehmer@alaskajournal.com.