Construction of one small hydroelectric project in Alaska is complete, and two more are being built. These three projects total 18 MW in capacity. Operation of these projects will eliminate the use of more than 2 million gallons of diesel fuel each year.
By Richard H. Levitt, Glen D. Martin, and Corry V. Hildenbrand
Three hydroelectric projects are under construction or recently completed in Alaska: 800-kW Falls Creek, 3-MW Kasidaya Creek, and 14.3-MW Lake Dorothy. Development of these three projects is intended to offset the use of expensive diesel fuel. Together, these hydro projects are expected to produce more than 88,500 megawatt-hours of electricity each year to supply cities in southeastern Alaska.
Construction of the 800-kW Falls Creek project about 45 miles west of Juneau, Alaska, is expected to be complete by the end of 2008. This project, being built by Gustavus Electric Co., will meet more than 90 percent of the electricity needs of the city of Gustavus and offset the use of about 20,000 gallons of diesel fuel a month.
Development of this project began in the early 1980s when Gustavus Electric Co., the power provider for the city of Gustavus, decided to explore the possibility of offsetting generation at its 1-MW diesel plant with hydropower. In 1983, the utility began looking into development of a hydroelectric project at a site 5 miles east of Gustavus. However, the proposed site was within the Glacier Bay National Park and Preserve, a marine wilderness under National Park Service control. This area includes tidewater glaciers, snow-capped mountain ranges, ocean coastlines, deep fjords, and freshwater rivers and lakes.
Gustavus Electric needed a way to gain access to this land for hydro development. In the end, getting rights to develop on this land took 15 years and an act of Congress. In 1998, Congress passed, and President Clinton signed, the Glacier Bay Boundary Adjustment Act, which authorized Gustavus Electric to submit a license application to the Federal Energy Regulatory Commission (FERC). The law states that, if FERC granted the license, a land exchange would be authorized between the National Park Service and the state of Alaska.
While it was lobbying for passage of this act, Gustavus Electric negotiated the terms of a lease agreement with the state. The terms provided the company with a 50-year lease and a renewal option for another 50 years. Once the Glacier Bay Boundary Adjustment Act was signed, Gustavus Electric and the state signed a lease agreement for the land on which the Falls Creek project is located.
After the act was passed, Gustavus Electric spent three years conducting environmental and engineering studies and preparing the FERC license application. In October 2001, the utility submitted its license application. Three years later, FERC issued the license.
In early 2006, ownership of the land was transferred from the National Park Service to the state of Alaska and, in turn, Gustavus Electric leased the land from the state. Work on the run-of-river facility began in April 2006.
The Falls Creek project consists of a gated diversion structure, 9,700-foot-long penstock, powerhouse containing a single turbine-generating unit, tailrace conduit, and 6.25-mile-long buried transmission cable. Gustavus Electric is performing the civil work for the project.
The diversion structure consists of two independently operated spillway gates on concrete abutments. Its foundation is 8 feet thick and 12 feet high. One spillway gate is 27 feet wide and one is 9 feet wide. The 8-foot-tall gates, supplied by Obermeyer Hydro Inc., are pneumatically operated.
On one side of the diversion structure is the intake, with a fish screen and a 30-inch-diameter penstock made of high-density polyethylene (HDPE). This section of penstock runs 5,500 feet, where it connects to 4,200 feet of 26-inch steel pipe that leads to the powerhouse, downstream on Falls Creek. The elevation of the pond behind the diversion structure is 665 feet; the powerhouse elevation is 63 feet. The steel powerhouse, supplied by Allied Steel Buildings, contains a turbine supplied by Canyon Hydro in Deming, Wash., and a generator supplied by Marelli Motori of Italy.
Flows from the powerhouse discharge into a 36-inch-diameter HDPE pipe. This pipe takes water 300 feet upstream from the powerhouse, to be released behind an engineered log jam. Gustavus Electric placed this log jam in the river to provide spawning habitat for salmon.
The transmission cable runs from the Falls Creek powerhouse to the substation behind the diesel powerhouse in Gustavus. As of September 2008, about a mile of cable remained to be installed. Gustavus Electric included a fiber-optic communication cable with the transmission line to provide communication capabilities for Falls Creek.
Other companies involved include R&M Consultants Inc. in Anchorage, Alaska, which is providing geotechnical services for the project, and Alaska Power and Telephone, which is acting as civil engineering consultant.
When the Falls Creek project begins operating at the end of 2008, the utility expects it to produce about 2,160 megawatt-hours of electricity each year.
Capacity: 800 kW
Gross Head: 600 feet
Annual Generation: 2,160 megawatt-hours
Turbine: 800 kW, 600 revolutions per minute
Generator: 4.16 kilovolts
Diversion Structure: Two pneumatically operated 8-foot-tall spillway gates: one is 27 feet wide, the second is 9 feet wide; attached to 8-foot-thick by 12-foot-high foundation; concrete abutments extend to bedrock
Penstock: 9,700 feet long; 5,500 feet of 30-inch-diameter high-density polyethylene pipe and 4,200 feet of 26-inch-diameter steel pipe
Powerhouse: Steel, 30 feet wide by 40 feet long
Development of this $8.5 million project is being financed through grants, loans, and equity. To date, Gustavus Electric has received $5.75 million in grants – $2.8 million from the Denali Commission (a partnership between the federal government and the state to provide cost-sharing of infrastructure projects), $1.5 from the Department of Agriculture’s Rural Utilities Service, and $1.45 million in appropriations from the state.
The 3-MW Kasidaya Creek hydro project in southeastern Alaska began operating in October 2008. The plant is expected to produce 11,900 megawatt-hours of electricity each year for developer/owner Alaska Power and Telephone Co. (AP&T).
AP&T began looking into development of Kasidaya Creek (formerly known as Otter Creek) more than a decade ago – at about the time the company applied for a FERC license to develop its 4-MW Goat Lake facility. Goat Lake, which began operating in December 1997, is a storage project, intended to operate year-round to meet the electricity needs of the cities of Skagway and Haines (100 and 75 miles north of Juneau, respectively). At the time, Skagway was just beginning to emerge as a popular tourist destination. To meet increasing electricity demand, the utility turned to hydropower as an alternative to diesel generation.
Hydro generation has a long history in Skagway. AP&T’s 943-kW Dewey Lakes run-of-river project, half a mile east of Skagway, began operating in 1902. With the addition of Goat Lake, AP&T was able to generate enough hydroelectricity to offset the use of almost 1.9 million gallons of diesel fuel each year. However, these two plants did not generate enough to meet electric needs year-round, particularly in late winter and early spring.
AP&T began exploring the possibility of developing another project 3 miles south of Skagway on Taiya Inlet. The proposed site was a narrow canyon in a remote, roadless area within the Tongass National Forest. Kasidaya Creek ran through the canyon. Stream gage data indicated high flows during the summer months – exceeding 1,500 cubic feet per second. AP&T determined that, by generating power at this site during the summer, it could reduce generation at the Goat Lake plant and thus collect more water in its forebay. That stored water could then be released through the powerhouse in the winter and early spring. In this way, AP&T would be able to meet peak winter demand without using diesel fuel.
AP&T filed for a FERC license for the project in 2002 under the name Otter Creek. FERC issued the license three years later. (In 2006, AP&T changed the name of the project to Kasidaya Creek.)
Construction began in April 2006. AP&T acted as the primary contractor and hired a construction superintendent who had just completed the utility’s 2-MW South Fork hydro project on Prince of Wales Island.
Construction challenges were significant. Because there were no roads to the site, construction personnel had to be ferried each day in a 35-foot aluminium boat with a ramp at its bow that could be lowered to the beach for loading and unloading. To get equipment to and from the site, AP&T used a mechanized landing craft, similar to the ones used by the military in World War II, to haul excavators, dump trucks, and cement trucks from Skagway to the project site. Often, equipment repairs could not be completed on site; the equipment had to be towed onto the landing craft and ferried back to Skagway. To aid the on- and off-loading, AP&T designed and built a special jetty. The jetty also acted as a breakwater to protect the personnel boat and the landing craft from waves, which can be as high as 4 feet in Taiya Inlet.
Much of the construction had to take place in the winter, when flows were at their lowest levels. During these winter months, outside temperatures at the site were well below 0 degrees Fahrenheit (F). Each day, in order to begin construction, snow had to be cleared off the access road. To keep the foundation forms warm before, during, and after concrete was poured, construction crews used heaters powered by diesel generators.
The 3-MW Kasidaya Creek project on Taiya Inlet in southeastern Alaska will provide electricity primarily during the summer months, allowing Alaska Power and Telephone Co. to avoid the use of expensive diesel generation.
The project features a 16-foot-high, 70-foot-long reinforced concrete diversion structure located in the canyon at 530 feet elevation. The structure’s right abutment includes rockfill on the downstream side for stability. The spillway is located in the center of the structure and includes an 8-foot-high, 36-foot-long pneumatically-operated gate supplied by Obermeyer Hydro.
The structure diverts water from Kasidaya Creek into the penstock intake on the left abutment. The 4,000-foot-long steel penstock drops about 500 feet to connect into the prefabricated metal powerhouse manufactured by Chief Industries Inc.
The powerhouse sits on the shore of Taiya Inlet west of the diversion structure. To preserve the natural beauty of the site, AP&T located the powerhouse behind an existing bedrock notch, which shields it from view. The powerhouse contains a single turbine-generator unit. Gilbert Gilkes and Gordon Ltd. of the United Kingdom supplied the Turgo turbine; Weg Maquinas Ltda. of Brazil supplied the generator. Phoenix Power Control Inc. (now North American Phoenix Energy Services) supplied the controls and switchgear.
Capacity: 3 MW
Gross Head: 537 feet
Annual Generation: 11,900 megawatt-hours
Turbine: Turgo, 3 MW, 900 revolutions per minute
Generator: 4.16 kilovolts, 4,100 kilovolt-amperes, 0.8 power factor
Diversion Structure: Reinforced concrete, 16 feet high, 70 feet long
Penstock: Steel and high-density polyethylene, 40 inches in diameter, 4,000 feet long
Powerhouse: Prefabricated metal, 28 feet wide, 480 feet long
AP&T employees played prominent roles in design and construction. Larry Coupe, senior civil engineer with AP&T, designed the civil works for the project. Bob Berreth, AP&T’s senior electrical engineer, designed the supervisory control and data acquisition (SCADA) network and switchgear; worked with Gilkes on the turbine design and Weg on the generator design; and installed the switchgear, transformer, and wiring. Vern Neitzer, the utility’s senior engineer, oversaw the design, conducted pre-licensing site surveys, aligned the turbine and generator, and supervised the overall construction activity.
Power from the project is transmitted from a 3,750 kilovolt-ampere generator step-up transformer manufactured by Pacific Crest Transformer into a submarine cable. This 15-mile-long cable feeds into transmission lines in the communities of Skagway and Haines. Pirelli-Jacobson Inc. installed this cable, with assistance from AP&T, in 1998 after Goat Lake was completed.
Estimated development cost for the project is $10 million, financed through a combination of AP&T funds and contributions from the Denali Commission. The commission provided more than half the funds needed to build the project. To finance the remainder of the cost, AP&T sold tax-exempt revenue bonds through the Alaska Industrial Development and Export Authority.
Alaska Electric Light & Power Co. is building the 14.3-MW Lake Dorothy project on Dorothy Creek in southeastern Alaska. When the project comes on line – expected in late 2009 – it will provide electricity to the city of Juneau.
The utility originally began developing the Lake Dorothy project in 1996 to supply power to a large gold mine to be installed in Juneau. However, two years into the FERC licensing process, the mine owner determined development of the mine was not financially feasible.
Without a customer to buy the electricity from the proposed project, the utility had to rethink its development plan. Development of the full capacity of the site – 45 MW – was no longer feasible. But, with increasing power demands in Juneau and anticipated growth in southeastern Alaska, the utility decided it could justify development of a 14.3-MW project and thus continued efforts to obtain a FERC license. FERC issued the license in December 2003.
The 14.3-MW Lake Dorothy project, under construction on Dorothy Creek in southeastern Alaska, will help meet electricity demands in the city of Juneau. The project is expected to begin operating in late 2009.
The project will draw water from three natural lakes that were formed by the movement of glaciers – Lake Dorothy, Lieuy Lake, and Bart Lake. In August 2008, JS Redpath Corporation of Sparks, Nev., completed construction of a lake tap in Lake Dorothy, 120 feet below the water surface. The lake tap was designed and executed by Norconsult of Norway. This lake sits at 2,400 feet elevation. Water extracted from Lake Dorothy will flow 340 feet through a 60-inch-diameter steel penstock to Lieuy Lake, at 1,711 feet elevation. The penstock, expected to be in place by the end of 2008, is being installed by JS Redpath, Harri’s Plumbing of Juneau, and North Pacific Steel Erectors of Juneau. MWH designed the penstock for Lake Dorothy.
Water exiting Lieuy Lake flows into Bart Lake, at 1009 feet elevation, via Dorothy Creek. The outlet of Bart Lake was controlled by a natural debris dam consisting of woody debris, talus boulders, and logs located at the outlet of the lake. This debris dam did not maintain a consistent lake level. Originally, Alaska Electric Light & Power planned to install a lake tap in Bart Lake to move the water to the powerhouse. However, independent engineers determined that the geology of the lake would not support the tap and recommended that the inlet works design be changed to a rockfill diversion dam with an impervious core.
Alaska Electric Light & Power is replacing the debris dam with a 31-foot-high diversion structure. This dam, designed by R&M Engineering and being constructed by Southeast Road Builders of Haines, Alaska, will allow Bart Lake to be maintained within its normal historic level of 1009 feet elevation. With the lake level at this elevation, the utility is able to construct the intake on the southwest shore of Bart Lake, about 100 feet east of the new diversion dam’s left abutment. The intake valve and 60-inch-diameter steel penstock will be located in a nearby ravine. Water will travel 8,300 feet through the penstock and connect with the Lake Dorothy powerhouse, at 33.6 feet elevation. The penstock was designed by MWH and is being installed by Southeast Road Builders.
The prefabricated steel powerhouse will contain a single 14.3-MW vertical six-jet Pelton turbine supplied by Gilbert Gilkes and Gordon Ltd. of the United Kingdom. The turbine connects to a generator supplied by Ideal Hyundai. Construction at the powerhouse site began in 2007. Southeast Road Builders excavated the site. North Pacific Erectors is building the powerhouse, which will be 58 feet wide by 69 feet long by 46 feet high.
The project is expected to produce about 74,500 megawatt-hours of electricity a year. Alaska Electric Light & Power will transmit the electricity via a new substation and 3.5-mile-long 138-kilovolt transmission line to the utility’s electrical transmission system that serves the Juneau area.
Completion of the Lake Dorothy project enables the utility to avoid the use of additional diesel fuel. Without this hydro project, new baseload diesel-fueled generation would have had to be developed to meet projected load growth in the Juneau area.
Development of the Lake Dorothy project is being financed through $60 million in tax-exempt revenue bonds. Alaska Electric Light & Power sold these bonds through the Alaska Industrial Development and Export Authority.
As load growth in Juneau continues to increase, Alaska Electric Light & Power plans to expand the Lake Dorothy powerhouse and install two additional 16-MW turbines. The lake tap installed in Lake Dorothy will be used to supply water to a 2,000-foot-long penstock that will lead into a 3.5-mile-long tunnel. This tunnel will take water to the Phase 2 powerhouse, which will be an expansion of the existing powerhouse. Alaska Electric Light & Power plans to begin work on this expansion in October 2009. n
Mr. Levitt may be reached at Gustavus Electric Company, P.O. Box 102, Gustavus, AK 99826; (1) 907-697-2299; E-mail: firstname.lastname@example.org. Mr. Martin may be reached at Alaska Power & Telephone Company, 193 Otto Street, P.O. Box 3222, Port Townsend, WA 98368; (1) 360-385-1733, extension 122; E-mail: email@example.com. Mr. Hildenbrand may be reached at Alaska Electric Light & Power, 5601 Tonogard Court, Juneau, AK 99801; (1) 907-463-6320; E-mail: firstname.lastname@example.org.
Richard Levitt, president of Gustavus Electric Company, is project manager for construction of 800-kW Falls Creek. Glen Martin is project manager for permitting, licensing, and compliance with Alaska Power & Telephone Company, which is building 3-MW Kasidaya Creek. Corry Hildenbrand, vice president of Alaska Electric Light & Power, is project manager for construction of 14.3-MW Lake Dorothy.
Capacity: 14.3 MW
Net Effective Head: 899 feet
Average Annual Generation: 74,500 megawatt-hours
Turbine: Six-jet vertical Pelton, 14.3 MW, 450 revolutions per minute
Generator: 13.8 kilovolts, 19,070 kilovolt-amperes, 0.75 power factor, three phase
Water Conveyance: Water flows from Lake Dorothy via a valve-controlled lake tap through a 340-foot-long steel penstock to Lieuy Lake. Water from Lieuy Lake flows into Dorothy Creek, then into Bart Lake. At Bart Lake, a 31-foot-high rockfill diversion dam and concrete intake structure direct flow into an 8,300-foot-long penstock to the powerhouse
Powerhouse: Prefabricated steel, 58 feet wide by 69 feet long by 46 feet high