Alaska Electric Light & Power to re-develop old hydro facility

Alaska Electric Light & Power on June 11 filed a statement of its intentions with the Federal Energy Regulatory Commission for the re-development of a long-abandoned hydroelectric facility on Sheep Creek located in the City and Borough of Juneau.

As it is presently conceived, the Sheep Creek Project would be a run of the river facility. There will be a small, approximately 10-foot high, concrete diversion structure. The diversion dam is estimated to be 75 feet long to span the width of the creek bottom. A 36-inch penstock approximately 4,750 feet long would carry water from the diversion to the powerhouse. The present penstock alignment will keep the penstock on the east side of Sheep Creek so there will be no stream crossings.

The powerhouse would be located near the mouth of Sheep Creek near the site of the abandoned powerhouse and adjacent to the existing AEL&P substation which serves the customers in the area. The powerhouse would house a single 3.3 MW generating unit.

A short tailrace would discharge directly into Sheep Creek at the base of the existing barrier falls. The existing barrier falls is located approximately 200 feet upstream of the existing highway bridge and provides a natural barrier to anadromous fish passage.

There would be a switchyard located adjacent to the powerhouse which consists of a single 3.5MVA transformer used to step the generation voltage up to 23-kV to tie into the existing electric transmission system. The switchyard would also include an automated switching device, instrument transformers and protective relaying.

In 1910, a hydroelectric facility was constructed at this site to provide power to the Treadwell mine located on Douglas Island. This facility was a run of the river project with a wooden diversion structure located at the same site as a new concrete diversion structure would be constructed. The powerhouse had three units, two 1000-kW units with 1900 hp Pelton turbines and one 225-kW generator connected between two 300hp Pelton turbines.

Eventually, the local mining operations ceased, and the hydroelectric facilities were transferred to A-J Industries who continued to sell power to AEL&P. Due to the load levels in Juneau and the need for winter power, the run of the river projects were shut down, while the storage projects remained in service. AEL&P bought the A-J Industries power generation facilities in 1972. By that time Sheep Creek had been shut down for over two decades and was in complete disrepair. Remains of the original diversion as well as sections of the original flume and penstock are still visible. The original powerhouse and turbine/generators are still intact. The new project does not propose to re-use any of these facilities.

About Barry Cassell 20414 Articles
Barry Cassell is Chief Analyst for GenerationHub covering coal and emission controls issues, projects and policy. He has covered the coal and power generation industry for more than 24 years, beginning in November 2011 at GenerationHub and prior to that as editor of SNL Energy’s Coal Report. He was formerly with Coal Outlook for 15 years as the publication’s editor and contributing writer, and prior to that he was editor of Coal & Synfuels Technology and associate editor of The Energy Report. He has a bachelor’s degree from Central Michigan University.