It is estimated that the proposed Donlin Gold mine would require an average load of 157 megawatts. To provide the amount of power required to operate the mine at peak capacity, a 14-inch, 312-mile-long buried pipeline to transport natural gas from the Cook Inlet region to the mine site is being considered. This would be an alternative to barging in diesel fuel from Bethel. If the pipeline is included in development, approximately two barges per day would take small amounts of diesel fuel and camp supplies from Bethel to a port site approximately eight miles down river from Crooked Creek, and would then be transported on a 30-mile access road to the mine site. Many other options to provide power such as coal, hydroelectricity, a power line intertie, biofuel, and even nuclear energy, were considered during the feasibility analysis but did not meet the current needs of the project.
A reclamation and closure plan is required by law to ensure when mining activity is completed, the mine is closed and the land is reclaimed and restored. The reclamation and closure plan is worked out in great detail and submitted to the permitting agencies for approval before the project is constructed.
To ensure that reclamation is properly carried out and meets permit requirements, the law requires the mine operator to provide financial assurance in the form of a bond or other financial insurance that is independently guaranteed.
Reclamation involves re-contouring the land, covering it with soil where needed and seeding it with vegetation native to the area. Reclamation will be ongoing through construction and operation as certain phases of the project are completed. Long after the mine is closed, environmental monitoring of the area will continue.
Once the mine is closed, Donlin is proposing to allow the open pit to fill with water and become a lake over a period of many years. The water quality of the lake will be continuously monitored and before any water is released it will be treated to meet strict water quality standards.
After completing all mining and milling activities, excess water will be pumped from a tailings storage facility to the pit lake. The tailings area will then be covered with rock and gravel. The tailings storage facility, along with the waste rock facility and other disturbed areas will be reclaimed by being re-contoured, covered with soil as needed, and seeded with a grass mix.
Over time, native trees and plants will naturally reclaim the area. All buildings and equipment will be taken apart and removed. Some material will be buried in permitted on-site landfill trenches that will be covered with soil and reclaimed, as required by regulatory agencies.
Extracting the gold at the Donlin Gold site will require significant processing:
- Crushing and grinding the ore in large grinding mills to create a fine silt-like powder
- Separating the gold-bearing minerals from other material in concentrating and washing circuits
- Applying heat, pressure, and oxygen in an autoclave to pre-treat the ore
- Dissolving the gold with cyanide solution in contained steel mixing tanks to extract it from other minerals
- Gathering the dissolved gold onto activated carbon and sending the cyanide solution through a cyanide detoxification process
- Extracting the gold from the carbon in a process similar to electroplating
- Refining the gold and pouring it into gold doré bars
Placer gold was first discovered at Snow Gulch, a tributary of Donlin Creek in 1909 during a rush to the George River by miners from the Iditarod-Flat District. Small-scale mining was conducted in the area from 1910 to 1940. After World War II sluice mining was conducted on Donlin Creek.
The Kuskokwim Corporation (TKC), a consortium of 10 upriver villages closest to Donlin, owns most of the surface land in the proposed mine area. The subsurface land is owned by Calista Corporation, a regional Native corporation formed under the Alaska Native Claims Settlement Act that encompasses 56 villages in the Yukon Kuskokwim (YK) region. Exploration in the Donlin Creek area over the years has been via lease agreements and contracts with these landowners.
Calista identified mineral potential in the region in 1975 and conducted prospecting and limited exploration activities from 1984 to 1987. The first substantial exploration drilling program was carried out by WestGold in 1988 and 1989. Placer Dome US (PDUS) explored the property from 1995 to 2000 and constructed a 75-person camp, 17 miles of road and a 5,000 foot long airstrip to support the advanced exploration and other programs.
In 2001, PDUS formed the Donlin Creek Joint Venture (DCJV) with NOVAGOLD as an operator. In February 2003, PDUS reassumed management of the DCJV as operator. PDUS initiated engineering and environmental studies and conducted an economic evaluation of the project and completed a resource estimate and continued with the pre-feasibility and feasibility studies.
Barrick Gold merged with Placer Dome in 2006 and acquired the PDUS interest in the DCJV. Approximately 1,784 exploration and development drill holes, totaling 132,493 m (403,705 ft), were completed from 1989 through 2008.
In December 2007, Donlin Creek LLC was formed as a limited liability company with 50/50 ownership by Barrick Gold North America and NOVAGOLD Resources Alaska, Inc. In 2011, the company’s LLC name was changed to Donlin Gold LLC. Activities at the Donlin Gold Project are managed by Donlin Gold LLC which oversees all aspects of development with input from both partners.