Name of the Project
Coffin Butte pumped-storage scheme project.

Location
The project is located on Coffin Butte, in Wheatland County, Montana, in the US.

Client
Absaroka Energy, through its single-purpose subsidiary, CB Energy Park.

Project Description
This hydroelectric facility will comprise an upper and a lower off-stream, closed-loop reservoir complex, with each reservoir sized at about 2 500 acre-feet.

The reservoirs will be connected by a buried, concrete and steel-lined penstock.

The lower reservoir will comprise:
• a 1 524-m-long, 15-m-high earth and roller-compacted concrete (RCC) embankment;
• a 20 ha lower reservoir, with a storage capacity of 2 500 acre-feet at an elevation of 1 584 m;
• a temporary diversion on Miller Creek, with a sump pump and pipeline to bring initial fill water to the lower reservoir;
• a well to bring groundwater to the project to compensate for evaporation and seepage losses;
• a powerhouse containing two reversible 125 MW turbine/generator units for a total installed capacity of 250 MW; and
• an a 3-km-long 230 kV transmission line connecting to an existing 500 kV transmission in the area or an 11-km-long 230 kV transmission line connecting to the Two Dot substation.

The upper reservoir will comprise:
• a 1 402-m-long, 15-m-high earth and RCC embankment;
• a 20 ha upper reservoir, with a storage capacity of 2 500 acre-feet at an elevation of 1 901 m;
• a 5-m-diameter, 1 524-m-long steel-lined tunnel extending to the powerhouse;
• existing ranch roads, along with 8 km of new access roads; and
• appurtenant facilities.

The proposed project will have an average generation capacity of 880 GWh/y.

Jobs to Be Created
Not stated.

Value
Not stated.

Duration
Not stated.

Latest Developments
None stated.

Key Contracts and Suppliers
None stated.

On Budget and on Time?
Not stated.

Contact Details for Project Information
Absaroka, tel +1 406 585 3006 or email contact@coffinbuttepumpedstorage.com.