Environmental, North America, Small Hydro

Alaskan 455-kW Gartina Falls small hydroelectric project to reduce diesel dependence

According to Alaska’s Energy Authority, Inside Passage Electric Cooperative Inc. (IPEC) is constructing a US$8.2 million run-of-river 455-kW Gartina Falls small hydroelectric project in Hoonah, Alaska that could reduce fossil fuel usage.

IEPC thinks Gartina Falls’ output will replace 30% of Hoonah’s diesel-powered electricity, and will help reduce electric rates for all five communities IEPC serves: Hoonah, Kake, Chilkat Valley, Angoon and Klukwan.

According to the Federal Energy Regulatory Commission license that was issued in 2013, the project must be completed by 2018.

The scheme involves a new concrete diversion dam that is 14 feet high and 56 feet long located on Gartina Creek in Hoonah. The dam will create a 1.7-acre reservoir.

The project’s dam will divert between 11 cubic feet per second and 110 cfs from Gartina Creek through the intake chamber to the project penstock, which will convey flows to the powerhouse. The powerhouse will contain one 455 kW horizontal cross-flow turbine/generator set, inlet piping, guard valve, switchgear, and controls.

The dam and intake structure is being constructed above Gartina Falls and a steel penstock, access road, and the powerhouse will be suspended over Gartina Creek, built at the base of the falls. After the flow enters the powerhouse and passes through the turbine, it will split the discharge.

To provide a constant source of water to the pool 125 ft downstream from the base of Gartina Falls, 10 cfs will be diverted to the base of Gartina Falls through the minimum flow discharge pipe. All remaining discharge flows over 10 cfs will be returned 205 ft downstream.