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By SAM ALLEN
Daily News Staff Writer
The City of Ketchikan has been running solely on hydropower for about a week — the longest such stretch this year.
This was achieved in part by above normal August rainfall in the Ketchikan area, including a single day downpour of about 4.85 inches.
Southern Southeast has been classified as in a severe drought by the U.S. Drought Monitor, a situation that has contributed to a heavy reliance on diesel generation over the past year to supplement hydropower.
The rush of rain allowed the Southeast Alaska Power Agency to bank about 15 feet of water in both Swan and Tyee lakes, allowing SEAPA to sell power from those hydro facilities to Ketchikan for the first time this year, according to SEAPA CEO Trey Acteson.
"(We're) completely 100% off diesel," said Ketchikan Public Utilities Electric Division Manager Andy Donato on Aug. 30, "but it's short-lived."
SEAPA shut down Tyee this week to perform some deferred maintenance, causing the northern communities of Petersburg and Wrangell to supplement with diesel.
SEAPA will shut down Swan Lake and the Swan-Bailey line during the week of Sept. 9 for deferred maintenance, and Ketchikan Public Utilities is expected to go back on diesel then, according to Donato.
During this diesel-free span, a significant portion of the hydro power has come from SEAPA sales. While it varies depending on peak usage, about 73% was coming from Swan Lake on the afternoon of Sept. 5.
After the next week of maintenance, Donato said they'll reassess with SEAPA and see what they can do for the rest of the month.
"Hopefully by then we'll get a little more inflows," said Donato, "and then we can evaluate what the rest of the year will look like."
The work SEAPA is doing on Tyee this week and the work it plans on doing to Swan next week will give the lakes a chance to recover with nobody drawing from them, according to Donato.
"And so hopefully, that will give us additional time to utilize those two resources without any diesel," said Donato.
Both Acteson and Donato said that the forecasts from NOAA show warmer and wetter weather for the next couple of months.
"Our typical heavy rain months will be September and October and November," said Acteson, "So, from a historical perspective, our rainiest months are ahead of us."
Donato said they used the diesel-free time this past week to repair Bailey units three and four.
"We had a bunch of exhaust leaks that we accumulated on (Bailey unit) three and we had some minor stuff on (Bailey unit) four," said Donato.
The Alaska Department of Environmental Conservation has recently approved KPU's permitting change requests for its Bailey units, according to Donato.
The diesels now have permits based off of gallon usage. Previously, the diesels had hourly permit limits that were based on full output, which the generators seldom run at, according to Donato.
Donato estimates that this change allow the utility to stretch the time of the diesels use by as much as 40%.
He said this allows KPU to rely more on these diesels, which are more efficient than the rental diesels. However, he said that there hasn't been a decision made on when to return the rentals.
On October 18, 2018, the Ketchikan City Council was notified that KPU Electric would be seeking additional generation capacity through the use of a rental generator program. Since Dec. 6, 2018, the City Council has approved four separate motions approving a total of approximately $1.32 million to operate the rental generators, according to a June citywide memo from Jeremy Bynum, KPU electric system engineering manager.
The rental diesel generators, which require frequent maintenance and fuel deliveries, have been moved nine times so far to satisfy permitting regulations, according to Donato.
"The last thing we want to do is get rid of these and then find out we're shy here going into the winter months," said Donato.
Current lake levels for the major lake contributing to Ketchikan's hydro generation — Upper Silvis and Swan — are both considerably lower than their 10-year average.
However, both Ketchikan Lake and Whitman Lake were within a foot of their historical average.
Swan Lake's 10-year average is around 320 feet this time of year and as of Friday it was around 300 feet. For Upper Silvis Lake, the elevation of 1,099 feet on Friday was about 24 feet shy of the 10-year average.
"So our lake levels are low. They're below the 10-year averages. We know that. And we're not out of the woods yet," said Donato.