Kasidaya Creeks diversion dam, more than 500 feet above Taiya Inlet, sends water 4,000 feet down a penstock, generating up to 3 megawatts of electricity. An excavator warms up for work outside the powerhouse.
Kasidaya hydro project now online
Story by Jeff Brady Photos by Andrew Cremata
KASIDAYA CREEK Alaska Power and Telephones Kasidaya Creek hydro project started operating round-the-clock on Nov. 13, providing Skagway and Haines with supplemental hydro power that the company hopes will eliminate the need for any diesel generation in the late winter and early spring.
The 3 megawatt operation had been under construction since April 2006. It was hoped to have the $10 million project completed this summer, but construction extended into the fall. The operation was tested over much of October, and was ready to crank up power to the Skagway-Haines grid in November.
Stan Selmer, AP&Ts regional vice president, took the News on a tour of the facility on Nov. 19. We boarded a crew boat at 7:30 a.m. for the 12-minute ride down to the site, three miles south of Skagway on the east side of Taiya Inlet.
The aluminum Ixoye, a former Thorne Bay school bus, has been hauling workers to the job site pretty steady for the past year and a half. They worked 10-hour shifts, six days a week.
Captain Tim Roseberg would take the crew down early in the morning, and return to get them late in the day. In between those trips, he would return to the small boat harbor and switch to a landing craft, hauling equipment and various loads of pipe, building materials, cement, and gravel to the remote site.
I bet we hauled 3,000 yards of D1 (gravel) on the landing craft, Roseberg said.
He said they only missed four or five days due to weather. On this day, the wind was blowing from the north, but the east side of the inlet wasnt too choppy.
Tim Roseberg lines up the boat with the Kasidaya launch. Ed Slattery sips coffee on the ride over.
A rock jetty sticks out about 50 feet to protect the boat from the more prevalent south winds. The boat lines up with wood pilings along the jetty, and then scoots up as far as it can. The bow scrapes bottom and a small gangway drops from the nose of the boat to the shore. The workers stream off.
On the day of our visit, there are just three who came down to work: plant operator Ken Nalan, and equipment operators Ed Slattery and Jim Shunn. Over the past year, during diversion dam, powerhouse and penstock construction, as many as a dozen workers were on the site every day. Now most of the work is checking instruments and cleaning up the site. This includes removing the last of the huge trees that were felled and stacked during road construction months ago. They are being hauled to Skagway for free firewood.
Theres a small building on the shore that sits over a vault, which serves as the junction box for connection to the underwater transmission line just offshore. A splitter line sends the power to Haines and Skagway, says Selmer.
About 25 yards to the south, hidden in a notch that cant be seen from the water, is the powerhouse and substation. The 24 by 48 steel building houses the Turgo turbine. The penstock comes in underground and then splits inside the plant, rising up to the turbine. Unlike the bucket-style Pelton wheel at the 4 MW Goat Lake powerhouse, the Turgo has vanes which catch the water as it flows through the turbine, causing the hub and shaft to turn, says Nalan. It came from England, and the generator is from Brazil. Theres a bank of North American controls along a far wall.
When running at 900 revolutions per minute during spring runoff, the Turgo will generate its full capacity of 3 MW. Right now, the onset of cold weather has the system operating at a tenth of that level.
We first went online last month at 800 kilowatts, now it is less than 300 KW due to the colder weather, Nalan says.
The plant is noisy and a step outside the back reveals the new raceway sending the water toward the inlet after its run through the turbine.
Ken Nalan and Stan Selmer inside the powerhouse. One of the pipes leading from the penstock to the Turgo turbine.
Back inside, in a small office, Nalan is checking a laptop that monitors the entire operation. Theres another in Skagway that employees are checking every two or three hours.
Its now automated to the point where we can monitor it in town, Nalan says. When it becomes fully automated, we can read (how much should run through it) based on the amount of water in Kasidaya Creek and Goat Lake.
He explains how Goat Lake, a storage facility, is the areas lead machine that they dont want to drop below 500 KW. When the system is fully automated, this (Kasidaya) machine will adjust accordingly, Nalan says.
The Kasidaya screen shows several monitor levels. Nalan can shift to a graph that shows power generation, and then bounce between various sensors in the powerhouse and up at the diversion dam. He notices that one at the dam is not working properly, so we head up the road to check it out.
We climb into a 4-wheel-drive pickup with chains. The road is fairly steep and follows the penstock, which is buried most of the way. The black 42-inch line emerges about two-thirds of the way up the road along a section where the bank was too steep to bury it. It crosses under the road and then levels out where we cross a bridge over Kasidaya Creek. The diversion dam is in view about 100 more yards up the creeks canyon.
We are at an elevation of 567 feet, but it seems higher due to the climb on the road, which is about 4,000 feet in length, same as the penstock.
The dam is 16 feet high and 70 feet long, though only about 40 feet of it is visible. Across the top in the center of the structure is an eight-foot-high, pneumatically-operated gate that is in the up position now. It can be lowered by regulating air in a long, pillow-like bladder when the water is high, so they can divert excess water to the creek over a spillway.
The water in the creek is currently about a foot and a half below the top on the back side, where the dam has created a small pool. Its level is being monitored by two Aquatape sensors. Nalan can see that one indeed has frozen up, so hell deal with that later.
The penstock intake is on the south abutment, behind which is a small 15 by 15 valve house where there are more monitors and indicator lights. One even watches the amount of rock and debris that might be accumulating near the intake. If theres too much, they can open up the sluice gate and flush it out, he says.
Nalan explains how they can control the level of the forebay, a small inlet that leads from the dam to the penstock, by increasing or decreasing the power being generated. Ideally, they like the forebay level to be the same as the pool level.
A closeup of the dam. A gauge shows 252.6 KW being generated that day.
Goat Lake actually has a smaller 24-inch penstock, but the 2,900-foot plunge to its powerhouse by the Skagway River creates 900-940 pounds per square inch of water pressure through its turbine, Nalan says. By comparison, Kasidayas drop of 567 feet through a bigger penstock results in 235 psi at its powerhouse.
Kasidaya allows AP&T to keep Goat Lake at a higher level through the winter, so it can continue to operate into the spring, when water is usually at its lowest levels. Higher demand in Haines and Skagway and low levels in Goat Lake this past year, resulted in an expensive switch to diesel generation that was passed on to customers.
Every kilowatt we can generate now (from Kasidaya) is that much that we dont have to generate by diesel in the spring, Nalan explained.
Slowly back down the road we go, getting a nice view of Harding Glacier across the inlet. Nalan says they saw some goats up here in the spring, and a bear was sighted early on when the road was being cleared. They looked for an old cabin that supposedly was used by an early prospector, Otto Patey. But its remains may be further up what was once called Paradise Valley.
As we descend the final steep section to the bottom, we can see an excavator working between the lower job site and the creek outlet to the south. Selmer says it is moving rock from the beach and placing some above the powerhouse to shore up the side hill, as well as removing rock to make easier access to the wood. Later that week, they moved five landing craft loads to Skagway for local residents to cut up. Eventually, the earth-moving equipment will head south to the companys next hydro project at Reynolds Creek on Prince of Wales Island, Selmer says.
Other than a kayaker who stopped by the creek mouth this summer, we have been the only non-work-related visitors whom they have seen.
But more will have an opportunity in the spring. On the trip back to Skagway, Selmer says an open house is being planned with public boat rides back and forth to Kasidaya.
By then it should be running at full capacity. That will be something to see, he says.