Alaska Electric Light and Power has filed an application with the Federal Energy Regulatory Commission to investigate the feasibility of a Sheep Creek hydroelectric project.
A public comment period is underway.
If the agency grants the permit, the Juneau company would be allowed to study the impact of what’s described as a diversion dam on Sheep Creek.
FERC spokesman Adam Beeco calls it a no ground disturbance permit.
“It’s essentially just reserving the site for the applicant to that land for a specific period of time. So essentially they’d have access to that site for studies, but not move any ground,” Beeco says.
The Treadwell Mine operated a small dam on Sheep Creek south of Juneau from 1910 to 1943. Most of the area already belongs to AJT Mining Properties, a sister company of AEL&P.
The project is described in the Federal Register as a 10-foot high, 75-foot long diversion dam at about 620 feet above sea level.
AEL&P generation vice president Scott Willis says the dam would create a small pond, deep enough to get the water into a pipe, called the penstock.
“We want to get the water that’s in the creek into the pipeline, so like on Gold Creek we’ve got a wooden diversion dam that keeps the creek high enough to flow into the flume. At Sheep Creek we would envision a concrete structure that would make enough of a pond to get the water to flow into a steel pipeline,” Willis says.
Willis says the pipeline would run along the surface, mounted on blocks, to a power plant below, probably located near the old plant on Thane Road.
“And then the water from the penstock flows through the unit in the power plant and then discharges in the tailrace and that will just go right back in that lower end of Sheep Creek,” Willis says.
Willis says the run-of- river hydro project would add about 3 percent to Juneau’s current hydroelectric sources.
When AEL&P brought the Lake Dorothy project online in 2009, it added 20 percent to Juneau’s hydro supply. A planned second phase would add another 20 percent, but the capital city would have to grow a lot to justify building out the project, Willis says.
Hydroelectric projects take years to plan, permit and construct.
“So we think this small, little chunk of energy could fit in nicely 6 or 8 years from now, just give us a little more energy. We’ll need a little bit more by then and that helps us postpone a much larger investment in Lake Dorothy phase two,” Willis says.
If FERC grants the permit, it would be for a period of three years and require environmental and engineering studies, including the impact on wildlife, fish and cultural resources of the Sheep Creek valley. Willis says he wouldn’t be surprised if it would take longer than three years to complete the feasibility study.
AEL&P submitted its FERC application in January. The 60-day public comment ends March 25th.
Brief comments can be submitted online, using the agency’s eComment system.
View Sheep Creek hydroelectric project in a larger map