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HomeMy WebLinkAboutKing Cove Hydro Project Engineering Excellence Awards 19951995 Engineering Excellence Awards King Cove Hydroelectric Project Category D3 Energy Production/Conservation Submitted By: li)~ HDR Engineering, Inc. 2525 C Street Suite 305 ~chorage,AJaska 99503-2689 Submitted to: Consulting Engineers Council of Al aska February 14, 1995 The King Cove Hydroelectric Project: HDR Engineering Brings Hydropower to King Cove King Cove, Alaska, on the Alaska Peninsula, is home to an 800 kW run-of-the-river hydropower facility recently constructed to replace the city's diesel-generation system. HDR Engineering's involvement in the project has encompassed every phase of this project, from feasibility studies and fmancing to design and construction management. By balancing the needs of the client with environmental and engineering design constraints, HDR has not only ensured the success of this project, but through its example, has made hydroelectric generation a more viable option for rural Alaska communities. Sandwiched between the stormy Gulf of Alaska and the even stormier Bering Sea, the community of King Cove is 624 air miles southwest of Anchorage and seven days via ship from Seattle. Like most communities in Alaska, no road links this community to another, so access is limited to air or sea transportation when weather permits. The same landscape that isolates King Cove from the rest of the state, however, also has made this area well suited for hydropower. The steep mountains that surround the community provide head and the area's 52 inches of snow and 33 inches of rain each year provide for the volume of flow. Although the area was generally well suited to this type of project, it was not without complex problems. Inaccessibility; grizzly bears; steep, glacial streams with high sediment and bedloads; near constant rain and snowfall; and 120 mph winds were problems that required original solutions. The city's·remote location posed one of the greatest challenges. During all phases of the project, traveling to the project site took a major effort of coordination. This was especially true during construction as the entire crew had to be relocated to the site, as well as housed and fed for the life of the project. What is even more unusual is that during initial site visits, team members carried shotguns for protection from the local grizzly bear population. King Cove's isolation made securing equipment a complex process, as all materials from the 9,000-pound flywheel to the correct nut to bolt it down had to be barged in from Seattle or flown in from Anchorage. With the week-long journey by ship from Seattle, the project leaders had to manage the project effectively to keep to its tight schedule and budget. As a product of this effort, the HDR team completed this $5.7 million project on time and under budget. The design and construction of the project also presented complex challenges that required innovative solutions. While most hydroelectric projects rely on a single source of water to drive the turbine, the required head could only be obtained by placing the intake high on the mountain and constructing two intakes on two branches of Delta Creek (Glacier Creek and Clear Creek). The high bedload and environmental constraints would not allow the impoundment of significant quantities of water, so a run-of-the-river design was required. These two characteristics -separate intakes and a run-of-the-river design-were accommodated with a unique concept for control. Located at a higher elevation, the Glacier Creek intake was designed as the primary source of water. Under normal con,, tions, this intake draws water from Glacier Creek and sends King Cove Hydroelectric Project Engineering Excellence Awards it to the powerhouse below. A check valve installed at the Clear Creek intake prevents Glacier Creek water from backing up through the Clear Creek intake during high flow conditions. When Glacier Creek flow becomes insufficient to meet the city's power needs, the pressure in the pipe drops and the water flows "open channel." When this "open channel" flow reaches the pool level of the Clear Creek intake, it triggers the intake to let Clear Creek flows into the system. This two-intake balancing act works without any mechanical controls, a unique, foolproof, passive control design. The HDR design also had to address the high bedload and sediment load in the tributaries. Because of the steep terrain and the relatively recent recession of glaciers from this area, both streams carry extremely high loads of sediment-as is evident by the large fan in Delta Creek and, hence, its name. Moreover, 8-to 12-inch boulders have been observed tumbling downstream during floods. To keep the intakes fully operational and reduce long-term maintenance needs, HDR designed a sluiceway with a side intake trashrack at each of the tributaries. Opening the sluice gate during floods allows bedload to flush harmlessly by the trashrack while turbine operation continues. To remove fmer materials, a sediment chamber with a separate sluice pipe is positioned between the intake grate and the penstock. To keep the intakes from becoming blocked by frazil ice in cold temperatures, HDR designed them to be submerged in small, quiescent pools. By enabling a layer of ice to form over the intake structures, the intake screen does not become blocked; instead, water flows under the ice surface and into the penstock. As a backup to these intake protection systems, water level sensors upstream and downstream of the intake trashracks alert plant operators if the trashracks become plugged. HDR's cold regions experience not only enabled the project team to identify a potentially serious problem, but allowed the company to engineer a cost-effective solution--one that did not carry a high operations and maintenance price tag. To best use the available head and flow, power is generated by a Gilkes Turgo impulse turbine, a dual-jet unit equipped with hydraulic deflectors to control flows. Design parameters were 292 feet gross head and 242 feet net head at full load. The rated synchronous generator output is 805 kW at 0.90 power factor. The unit also includes a speed governor because it was designed to operate as the sole source of power for the community. As is typical of small communities in Alaska, King Cove's system is not connected to another town's electrical system or to a grid system. To accommodate fluctuations in user loads that would otherwise be absorbed by a grid network, HDR's design included a 9,000-lb flywheel. This flywheel both stores and provides energy to ensure smooth transitions during load changes. With a peak city load of 500 kW, the existing city system could not produce the load required for proper testing. Moreover, the constant on-line and off-line operations inherent to the start-up debugging sequence would neither be convenient to city residents nor easy on electrical equipment. Instead of settling for a scaled-back testing process or risking city equipment, a "water rheostat" was constructed as a load bank. The HDR team hauled an empty, 3-yard dumpster from town, fllled it with salt water, installed copper electrodes, and connected it to the hydroelectric facility. The salt provided the conductivity, the electrodes linked the dumpster 2 liR King Cove Hydroelectric Project Engineering Excellence Awards directly to the generator, and the heating of the water provided the demand for power. With the entire King Cove projected load for the year 2020 distributed to the dumpster, the project team tested the operation of the new equipment from no output to full capacity with no impact to the city system. Making certain this system could handle the residents' projected electrical needs was particularly important because King Cove is a rapidly expanding community. In five years the current diesel system would not have met the city's demand. Providing for this community's growing electrical needs is a necessary part of maintaining the residents' standard of living. Although the design and construction of a 800 kW hydropower facility may not be considered unusual in the lower 48 states, this effort in Alaska is ground breaking. King Cove's interest in hydroelectric projects has spanned a decade, but HDR was the first finn to make it a reality. King Cove, with its steep mountains and high precipitation, could be any of a hundred communities in Alaska. Because of King Cove's success, it will become a prototype for all other facilities in the region. In demonstrating that a hydropower facility can meet a city's long-term electrical needs, HDR has begun a transition from more expensive, diesel-burning systems to the cheaper, cleaner option of hydropower. Given the uncertain future costs and storage requirements of diesel fuel and its impact on the environment, residents have been pleased to learn that the new system is saving the city over 400 gallons of fuel each day. As summed up by City Manager Gary Hennigh, "HDR's work has been incredibly well received by the community, and the residents are thrilled with the product." By overcoming extraordinary environmental and technical challenges in one of the country's most remote locations, HDR has improved the quality of life in King Cove and forever secured a niche for hydropower in Alaska. 3 ~ COVE HYDROELECTRIC PROJECT OWNER: RDA CITY OF KING COVE, ALASKA HDR worked with the city through every step of the process from feasibility studies and financing to design and construction management. King Cove's remote location presented unique challenges to the project team. Field work for the feasibility study, for example, required team members to tote shotguns for protection from grizzly bears. The area's 5,000 foot mountains and heavy precipitation made the landscape well suited for hydropower. Note the two intakes on the left-and right-hand sides of the photo. Wit h no roads linking King Cove to another community, access was limited to air or sea transportation when weather permitted. Barges like this one brought equipment and materials from Seattle or other locations in Alaska. Before construction During construction Before and during construction shots of the Glacier Creek intake, one of the two intakes needed for this run-of-the-river design. Set at different elevations, the two intakes required an engineering balancing act to make them work successfully. During construction After construction During and after construction shots of the Glacier Creek intake, one of the two intakes needed for this run-of-the-river design. Set at different elevations, the two intakes required an engineering balancing act to make them work successfully. With a short construction season, crews built the intakes between June and September. Crews built and buried 6,700 feet of 32-inch steel penstock from the intake to the powerhouse. A multidisciplinary effort, this project involved water resources, transportation, and other elements, as captured by this shot of a road and pipeline crossing. Because the existing system could not produce the load required to test the facility, HDR transformed this dumpster into a load bank. By filling it with salt water, installing copper electrodes, and distributing the entire projected load for the year 2020 to it, the team tested the facility to full capacity. City of King Cove Located 5 miles from town, 2 miles of new road was required to access the hydropower facility, which consists of intakes on two tributaries of Delta Creek, 6,000 feet of buried penstock, a powerhouse, a single 800 kW impulse turbine and generator, 5 miles of buried electric cable, and a SCAD A system for remote monitoring and control. Funding 1993-1994 HDR's Involvement in the Project Feasibility Study 1991 Delta Creek Topographic Mapping 1992 Final Design Work 1994 Procurement of Materials 1994 Construction 1994 King Cove Hydroelectric Facility OnLine November 1994 Environmental Studies and Permitting 1993 Funding Sources lOr the King Cove Hydroelectric Project Grants: State/ Alaska Energy Authority $2,500,000 (granted to city) State/Deparnnent of Administration $500,000 U.S. Deparnnent ofEnergy Aleutians East Borough City of King Cove Loans: Farmers Home Administration (Hickel Administration match of Aleutians East Borough/ City of King Cove/State of Alaska funds) $250,000 (through Tribal Council) $250,000 $250,000 (cash from city permanent fund) $I ,800,000 (25 years/ 5.5% interest) CITY OF KING COVE February 14, 1995 Awards Selection Committee Consulting Engineers Council of Alaska Anchorage, Alaska Subject: Engineering Excellence Award for the King Cove Hydroelectric Project Dear Selection Committee: Since November 1994 the King Cove hydroelectric facility has been on line, providing for the electrical needs of about 200 households and ten commercial and government facilities. A major part of the city's success in seeing the hydroelectric project become reality was our steadfast confidence and faith in HDR Engineering. HDR oversaw all phases of the project. Each member of the HDR team provided consistent and timely professional guidance throughout the project. Project Manager Duane Hippe is an extremely competent engineer, and even more importantly, he is a quality individual. These two factors were very instrumental in our decision to go with HDR the whole way on this project. For bush communities contemplating similar projects, this experience has shown me that it is imperative early in the process to secure the services of professionals who clearly understand both the community and the range of technical and financial components of the project. These professionals must be trustworthy, so you feel confident taking their advice and comfortable voicing any concerns. HDR Engineering was just that firm to the City of King Cove. Through this firm's efforts, the city has made its vision for a hydropower facility become reality. Sincerely, 1 . , _jLL~--((j~ ;;i Gary4fennigh City Manager 1600 A STREET. SUITE 103 ANCHORAGE, AK 99501·5146 (907) 274-7555 (907) 276-7569 FAX P.O. BOX 37 KING COVE, AK 99612 (907) 497-2340 FAX (907) 497·2386