Blue Lake Dam expansion project: Sitka hopes to keep up with electrical demand.

AuthorSwagel, Will
PositionENERGY

When Sitka Electric Utility Director Chris Brewton first got to town in 2008, he was shocked to see "piles of plug-in electric heaters" being unloaded outside a local hardware store. In Sitka to head the municipally-owned electric utility, Brewton was interested and asked the guys doing the unloading what was going on. He was told that scores of Sitkans were coming in and scooping up the electric heaters for their homes.

So Brewton checked the books and saw that the demand for electricity had increased along with the price of heating fuel, which had more than quadrupled--rising from 71 cents a gallon in 2002 to $3.24 per gallon in 2008. (At this writing, in April, No. 2 heating fuel is selling for $3.96 to $4.18/gal. in Sitka.) During that period, Sitka also experienced a significant increase in seafood processing capacity, spurring another large increase in electrical demand. Home builders were using electric heat in new construction. At $2.85 per gallon, officials estimated that electric heating had become cheaper than oil.

Sitka is blessed with excellent hydropower resources. For nearly 20 years, plenty of electricity was supplied by two dams--one at Blue Lake (built in the 1950s) and one at Green Lake (built in the 1980s). But in the last five years or so, a combination of the increased demand and low rainfall has led to more and more reliance on expensive diesel generators to fill the gap.

Solving the Shortage

Construction on the solution to Sitka's power "shortage" began late last year. Sitka plans to raise the 210-foot-high Blue Lake Dam. Luckily, the dam was originally built to be strong enough so that it could be raised in the future.

"Somebody had some foresight," says Richard Linden of McMillan LLC, the construction manager on the job, who has more than 30 years experience building dams. "Normally, you would not be able to raise a dam without going down to the bottom and reinforcing it from the bottom up. Not to say it hasn't been done before, but it's unusual."

The Blue Lake Expansion project is pegged at $145 million, to be paid with a combination of state grants and the sale of municipal utility bonds.

The plan is to raise the concrete arch dam by 83 feet to an elevation of 425 feet, in order to collect that much more water, bring the flow down the mountainside to a newly built powerhouse, and then use the increased water flow to run up to three generators. The project is expected to generate an average of 94,000 megawatt...

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