KETCHIKAN – After a summer of record-setting rainfall, the Swan Lake Hydroelectric Facility reached full capacity following expansion totaling an additional 15 feet of storage for the first time. Due to drought conditions since construction was finished three years ago, this summer marked the first time water levels made it all the way up on the flashboards, forcing a reservoir spill on July 24.
“This expansion allows for increased storage of one of our area’s most important renewable energy sources: hydropower,” said Sen. Bert Stedman, R-Sitka. “This expansion ensures that we can store more hydropower and use it during the fluctuating rainy seasons. This is just a part of a larger ongoing expansion, and we are currently reviewing other hydropotentials to increase storage generation in the future.”
The Swan Lake Reservoir Expansion Project achieved its objective of increasing regional hydro storage capacity, which was identified as a priority in the Southeast Alaska Integrated Resource Plan. The expansion was a 22MW hydroelectric facility on Revillagigedo Island that expanded the capacity from 86,000 acre-feet to 111,800 acre-feet, allowing for about 25-30% more storage.
PPM was contracted to perform concrete demolition work on the spillway, procure and place Owner-designed embedded metals and seal plates for the flashboard system (a unique element to this project), erect the flashboard system, place Owner-provided embedded metals for the vertical gate and erect the vertical gate, place reinforced concrete on the wing walls, construct a new reinforced concrete center pier, and modify and seal existing parapet walls. PPM also made modifications to the intake building and constructed a utility trench and conduit bank that carries tubing and cabling from the intake building to the new vertical gate.
“This is a great example of maximizing the value of an existing hydroelectric asset without the need for additional transmission or powerhouse infrastructure,” said SEAPA CEO Trey Acteson.
The project was completed on an accelerated schedule and came in under the engineer’s estimate of $13.3. million. It was partially funded through a $3.9 million direct appropriation from the State of Alaska and SEAPA sold bonds for the remaining balance. Alaska’s congressional delegation supported the project, as well, which subsequently led to the passage of related Swan Lake Boundary Adjustment Act. Numerous state agencies and the U.S. Forest Service also worked collaboratively to bring the project to fruition.