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By Dan Rudy 

SEAPA to look into Tyee expansion

 


At its board meeting in Ketchikan April 28, Southeast Alaska Power Agency agreed to look into the feasibility of putting in a third generating unit at the Tyee Lake hydroelectric facility.

The proposal was put forward by board members representing Wrangell and Petersburg, whose communities Tyee predominantly powers.

Operating since 1984, the Tyee hydro facility uses water from a natural lake, which is funneled into a drop shaft feeding two generating units that together generate 25 megawatts of power. In the original construction, the foundation for an eventual third unit was included.

SEAPA CEO Trey Acteson explained addition of a third unit would on its own be a capacity increase to the facility, allowing it to take on additional load as needed or serve as a redundancy. Even with the additional turbine in place, Tyee would still have the same lake to rely on, which covers about 52,400 acre feet of active storage.

Though primarily benefitting SEAPA’s northern communities, the addition of a third unit on its own would be different from work currently being undertaken at the Swan Lake hydropower facility, which provides power to Ketchikan and Saxman. Its dam is being raised to increase its overall energy reserves – in this case, water stores – by 25 percent.

In order to make the Tyee addition worthwhile, building a dam may be necessary – a significant investment, possibly costing as much as $20,000,000.

“We’ve looked at it in-house before,” Acteson said.

A weir installed by SEAPA at the Tyee outlet in 2014 replaced an old federal gauging station will aid in a hydrosite analysis of the basin. Wrangell’s board alternate, Clay Hammer, explained that between the analysis and feasibility study, SEAPA will have a better idea of whether an expansion of the Tyee facility would be a prudent investment.

Moving ahead, SEAPA staff will look into finding an appropriate consultant, to be paid through the agency’s professional services fund.

“It would just be nice to see that project going forward,” commented Steve Prysunka, Wrangell’s voting member on the SEAPA board.

Work on the Swan Lake project is underway, anticipated to wrap up later this year. Final contract details and legal reviews are ongoing, contractor bond and insurance deliverables in progress, and pre-construction planning being finalized with contractor Pacific Pile & Marine.

Acteson explained that controlling Swan Lake’s levels during the construction process will be imperative to the project’s success, as water cannot be allowed to spill due to work being undertaken on the dam’s spillway. As a result, water can only be run through the dam’s turbines.

To help maintain this control, SEAPA solicited bids for a 5-megawatt load bank to produce excess load. Three came in, and the after discussion the board approved contract with Marsh Creek LLC of Anchorage for $239,754.

SEAPA has also proposed a generation adjustment with Ketchikan Public Utilities, having it turn down some of its own hydro assets at in order to help the Swan project. Acteson anticipated a review meeting with KPU management this week, with a draft to be put before the board at once both sides have reached a preliminary agreement.

“We should have something worked out – hopefully as soon as possible – should the need arise,” Acteson reported.

Other renewal projects are continuing or have been completed. Operations manager Steve Henson reported installation of a new satellite communications and phone system at Tyee Lake will be ongoing over the coming six weeks, the second half of 100 aluminum helipads needed to service the Swan-Tyee Intertie line will be finished over the summer, and line maintenance at Tyee Lake has been scheduled from May 31 to June 7. During that time, Petersburg and Wrangell have to switch to their own power supplies while the hydro facility is taken offline.

 

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