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Grand Coulee Powerplant
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| Region | Facilities in Pacific Northwest | Pacific Northwest Home Page |
| State | Washington |
| River | Columbia River |
| Purpose | Grand Coulee Dam is a key feature of Reclamation`s Columbia Basin Project in central Washington. A multi-purpose project, it provides flood control, irrigation, hydropower production, recreation, stream flows, and fish and wildlife benefits. Facilities at the dam include three powerplants, a pump-generating plant, and three switchyards. Franklin D. Roosevelt Lake behind the dam is 151 miles long with over 5,000,000 acre feet of active storage. Water is pumped for irrigation in the Columbia Basin to irrigate approximately 670,000 acres with an ultimate potential of 1.1 million acres. |
| Facts | Grand Coulee Dam is the largest concrete structure built in North America. Raising the water surface 350 feet above the old riverbed, the dam is 5,233 feet long, 550 feet high, and contains 11,975,500 cubic yards of concrete. The original dam was modified for the Third Powerplant by a 1,170-foot-long, 201-foot-high forebay dam along the right abutment approximately parallel to the river and at an angle of 64 degrees to the axis of Grand Coulee Dam. |
| Facts | The power facilities at Grand Coulee Dam consist of a powerplant on both the left and right sides of the spillway on the downstream face of the dam. The Third Powerplant, on the downstream face of the forebay dam, the pumping generation plant on the left abutment of the dam, and an 11.95/115-kilovolt switchyard, a 230-kilovolt consolidated switchyard, and a 525-kilovolt Third Powerplant cable-spreading yard and switchyard are located high on the hills west of Grand Coulee Dam. |
| Facts | The Left Powerhouse contains three station service generators rated at 10,000 kW and nine generators rated at 125,000 kW. The Right Powerhouse contains 9 generators rated at 125,000 kW. The Third Powerplant contains three generators nameplate rated at 600,000 kW but able to operate up to 690,000 kW, and three generators rated at 805,000 kW. The Pump-Generating Plant contains six pumps rated at 65,000 horsepower, two pump-generators rated at 67,500 horsepower, and four pump-generators rated at 70,000 horse-power. Each of the generators is fed by an individual penstock with the largest (Third Powerplant) approximately 40 feet in diameter and carrying up to 35,000 cubic feet per second of water. One switchyard has 11.95 kilovolt distribution and four 115 kilovolt transmission lines; one switchyard has 230 kilovolt generation (from eighteen 125,000 kW units) and eleven transmission lines; the third switchyard has 525 kilovolt generation (from six Third Powerplant Units) and four transmission lines. There are electrical connections through transformers between the 115 and 230 kilovolt switchyards and the 230 and 525 kilovolt switchyards. The main dam contains 11 drum gates, each 135 feet long and 40 outlet tubes with 102-inch ring seal gates for spilling water. The average water released from Grand Coulee Dam is 110,000 cubic feet per second. The average power generation is 21 billion kilowatt hours per year |
| History | Construction of the original project started in 1933 and was completed in 1942. The first power was generated in 1941 and the last of the original 18 units (Right and Left Powerhouses) began production in 1950. Pumping for irrigation commenced in 1952 with six pumps installed. Six pump-generators were installed from the mid-1970`s (P/G-7 and P/G-8) to the early 1980`s (P/G-9 through P/G-12). Construction of the Third Powerplant and Forebay Dam commenced in 1967 with the first unit (G-19) commissioned in 1975 and the last (G-24) in 1980. The 18 original generators in the Right and Left Powerhouses have had the stator windings replaced increasing the rating from the original 108,000 kW to 125,000 kW. The last three generators in the Third Powerplant (G-22, G-23, and G-24) had their stators and cores replaced increasing their rating to 805 MW at 825,640 kva and power factor of 0.975. Six banks (18) of the original transformers in the Left Powerhouse have been replaced with the ratings increased to 129,000 kilovolt amperes. |
| Present Activities | A contract was awarded to Grand Coulee Consortium (GCC), consisting of GE Hydro of Lachine, Quebec, Canada and VA Tech of Linz, Austria, to replace the turbine runners on main unit generators G-1 through G-18. The contractor has completed 17 units, with G-8 being the last to be completed in FY2010. |
| Present Activities | Replacing 500 kV Cables with Overhead Lines:
The degraded condition of high voltage cables that transmit power from the TPP and across the dam to the switchyard constitutes an unacceptable risk for loss of generation. The nine oil-filled cables for G-19, G-20, and G-21 have been operated near or above their continuous current rating for 30 years. Because they cross the river in a common underground tunnel, failure of one cable has the potential to destroy all nine cables and take all three generators out of service for at least one year. Replacing these cables with overhead transmission lines will remove the potential of one cable failure causing the loss of 2,100MVA or more of generation. |
| Present Activities | Modifying the Fixed-wheel Gate Repair Chamber for Blasting and Painting:
This project will modify the chamber to allow blasting and painting of TPP fixed-wheel gate components and be in compliance with Life Safety and Electrical Codes. At present, the wiring is not explosion-proof, ventilation is inadequate, separation from dam galleries is inadequate, and lighting is inadequate. All these factors lead to potential violations of code requirements if work is undertaken during seasons when blasting and painting cannot be done outdoors. Fixed-wheel gates from the six TPP penstocks can be moved by gantry crane from their individual chambers to this modified chamber for repair or refurbishment.
The project is well underway, with planning and VE studies completed, and final design scheduled for completion in FY2009. The next phase, procurement, will cover purchasing, installing, and commissioning the new equipment using traditional procedures.
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| Present Activities | Rehabilitating TPP Cranes:
There are six cranes which will see heavy use during the TPP unit overhauls. There are three upper bridge cranes, one 2,000-ton lower bridge crane, one draft tube gantry crane, and one forebay gantry crane. It is imperative that they all be in excellent working order prior to the overhaul work for use by contractors and the GCPO in order to prevent unplanned crane outages that could result in costly delays in the overhaul schedule.
Repairs and upgrades of these cranes in preparation for overhaul was the subject of a crane consultants inspection and report that was completed in September of 2008. This TPP work is intended to be combined with rehabilitation of other facility cranes as long as the TPP work can be completed prior to the generator overhaul contract.
The consultants recommendations have been reviewed and utilized to prepare preliminary design concepts. The concepts have undergone Value Engineering (VE) study to ensure that needed function and value were addressed in selecting the final alternatives for design.
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| Present Activities | A contract was awarded to replace eight station air system air compressors with installation completed in FY 2005. A contract was awarded to upgrade the 11.95-kV switchgear. A new arrangement of switchgear is currently being installed which will provide better reliability for station service power to the switchyards. Completion of this upgrade is scheduled for FY2009. |
| Present Activities | Efforts continue with specification preparations, issuing a request for proposals and review of proposals for a new Supervisory Control and Data Acquisition (SCADA) System. |
| Present Activities | New Material Storage Building:
Overhaul of the TPP turbines and generators requires lay-down space for all turbine and generator parts as they are removed. These and other incidental parts will occupy nearly all of the TPP floor space. There are a variety of spare parts and pieces presently being stored in the TPP that need to be removed in order to provide the needed overhaul lay-down space. These valuable and easily damaged spare parts need to be kept in a secure, covered, and heated storage space. The proposed new storage building will be built to provide this space in a location convenient for movement of materials to and from the TPP. Preliminary plans for this building include a 100-foot by 200-foot floor area with 30-foot walls, 30-foot by 28-foot door (same opening as the north TPP door), insulated walls and ceiling, heating and cooling, forced ventilation, power, compressed air, and a life safety system with fire suppression.
The GCPO facilities are considered part of a historically significant area. As such, this new storage building cannot detract from the overall appearance of the area. The storage building will be much smaller than the TPP and will retain the historical context of the site.
The general size and requirements of the building have been established and the VE study has been completed. Design of the building is scheduled to begin in June 2009.
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| Present Activities | TPP 236 MVA Transformer Replacement:
New transformers will replace the six single-phase 236-MVA transformers comprising the generator step-up transformer banks for generators G19 and G20. These banks of transformers have been in continuous service since 1975. Identical transformers in an adjacent bank were replaced in 2002 because of deteriorating conditions. When these types of transformers deteriorate they produce flammable gases within the cooling oil. Close monitoring is required to prevent gas build up and the potential for explosion. Due to potential for explosion, access to this transformer area has been restricted. An explosive failure could damage cable circuit terminations and adjacent transformers which would compound immediate power loss and lengthen recovery time. Spares for these transformers are not available in the Northwest. Design for this project is complete and the procurement process is scheduled to begin in July 2009. |
| Future Planned Activities | A recent failure of a single phase transformer on Unit G10 resulted in re-evaluation of the need for replacement transformers. Additional replacement transformers for four units in the Left Powerplant will be purchased beginning in FY2010. Due to condition and age of the transformers in the Third Powerplant, 6 new 236MVA transformers will be purchased. This will provide more reliable service between the powerplants and the switchyards and for the power system.
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| Future Planned Activities | The Third Powerplant units are approaching the time for mechanical overhauls. Planning efforts are underway. Project personnel are working with the Bonneville Power Administration (BPA) and the capital work group of the Bureau/BPA's Joint Operating Committee (JOC). They are working on various capital replacement items of the project including unit's excitation systems, governor control systems, station service equipment, and switchyard circuit breaker replacement.
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| Special Issues | Since Grand Coulee has such a large amount of generation; it is used as a peaking facility by BPA. Fluctuations in the downstream tailbay/river have required extensive downstream stabilization measures, including elaborate monitoring and pump systems to maintain riverbank stability. |
| Special Issues | Water releases from Grand Coulee play a significant role in providing water for the fish that have been listed under the Endangered species Act. In addition, to the extent possible, spill is minimized to keep the Total Dissolved Gas (TDG) below the state standards. As part of the power peaking operation the pumps and pump-generators in the Pump-Generating Plant are load factored (use for pumping during light load hours) to allow BPA to sell more power during peak hours and also to provide a load during light load hours (to reduce spill). The pump-generating plant provides an approximate load swing - from consuming 600 MW with all 12 units pumping to generating 300 MW with 6 pump-generators generating. |
| Special Issues | River operations have been modified to comply with biological opinions and court decisions. The water supply for FY2009 above Grand Coulee was sufficient to provide benefits for endangered species, power supplies, and agricultural growers. |
| NERC Region | Western Electricity Coordinating Council, Northwest Power Pool Area |
| PMA Service Area | Bonneville Power Administration |
| Plant Type | Conventional |
| Powerhouse Type | Above Ground |
| Turbine Type | Francis |
| Original Nameplate Capacity | 1,974,000 kW |
| Installed Capacity | 6,809,000 kW |
| Year of Initial Operation - Left and Right Powerplants | 1941 |
| Year of Operation - Third Powerplant | 1975 |
| Year of Operation - Pump-Generator Plant | 1973 |
| Net Generation | 21,890,698,375 kWh |
| (Fiscal Year) | 2008 |
| Rated Head | 330 ft |
| Plant Factor | 38.24 percent |
| (Fiscal Year) | 2008 |
| Production Mode | Intermediate |
| Remotely Operated | No |
| Project Authorization | The Columbia Basin Project began with fund allocation for Grand Coulee Dam pursuant to the National Industrial Recovery Act of June 16, 1933. The project was specifically authorized for construction by the Rivers and Harbors Act approved August 30, 1935. The Columbia Basin Project Act of March 10, 1943 (57 Stat. 14), reauthorized the project, bringing it under the provisions of the Reclamation Project Act of 1939. |
| Project Authorization | Construction of the Third Powerplant was authorized by Public Law 89-448 (80 Stat.200) dated June 14, 1966, as amended by Public Law 89-561 (80 Stat. 714) dated September 7, 1966. |
| Project Purpose | The Columbia Basin Project is a multi-purpose development using part of the resources of the Columbia River in the central part of the State of Washington. The key structure, Grand Coulee Dam, is on the main stem of the Columbia River about 90 miles west of Spokane, Washington. The extensive irrigation works extend 125 miles southward on the Columbia Plateau to the vicinity of Pasco, Washington, where the Snake and Columbia Rivers join. The project irrigation facilities are designed to deliver a full water supply to 1,095,000 acres of land previously used only for dry farming or grazing. Of the 1,095,000 acres, approximately 550,000 are currently irrigated. Power production facilities at Grand Coulee Dam are the largest in North America. |
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Last updated: Jul 10, 2009
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