GRANDCOULEEPOWERPLANT
Grand Coulee Dam and the Third Powerplant, Right Powerplant, and Left Powerplant
Aerial View of Grand Coulee Dam |
Installation of a Turbine at Grand Coulee Third Powerplant |
| Plant Contact: | David Murillo Power Manager |
| Telephone Numbers: | Phone:509-633-9507 Fax: (509) 633-9138 |
| E-Mail Address: | dmurillo@pn.usbr.gov |
| Reclamation Region: | Pacific Northwest |
| NERC Region: | Western Electricity Coordinating Council, Northwest Power Pool Area |
| PMA Service Area: | Bonneville Power Administration |
| 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. 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 Purposes: | 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. |
| Plant Facts: | Grand Coulee Dam is the largest concrete structure ever built. This barricade, which raises the water surface 350 feet above the old riverbed, 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. 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. 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. |
| Plant 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 550,000 acres with an ultimate potential of 1.1 million acres. |
| Plant 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: | Replacement of the original main unit (G-1 through G-18) and respective transformer protective relays are being replaced along with replacement of the original 460-volt power circuit breaks, the 250-volt DC breakers and the 120-volt AC control breakers. In conjunction with this work old lead covered control cable is being replaced and control system upgrades are being performed. This work is being performed during outages for the contractor replacing the turbine runners. 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 first runner was installed on unit G-3 and tested during the week of October 22, 2001. The peak efficiency measured was 95.6 percent at 323 feet of head and a servo stroke of 78 percent. This compares to the original peak turbine runner efficiency of approximately 92 percent at this head. The contractor has completed 10 units, 6 in the Left Powerhouse and 4 in the Right Powerhouse. The contractor was nearly completed with G-14 (Right Powerhouse) by the end of FY 2007 and is continuing manufacturing and installing turbine runners on one unit in the Left Powerhouse and one unit in the Right Powerhouse concurrently. The contractor has proposed an accelerated schedule in order to complete the project earlier than is currently scheduled. Pump Unit P-3 had it’s impeller replaced by a contractor. During return to service checkout procedures, a seal ring failure occurred requiring the contractor to correct the problem. Return to service is scheduled for early spring of calendar year 2008. A stator core and winding replacement is scheduled for this same unit in the fall of calendar year 2008. 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 FY2008. A contract was awarded to provide new generator air housing coolers for units G1-18. The first set of coolers will be received in FY2007 with the remainder to be supplied in FY2008. A contract was awarded for upgrading 5 elevators throughout the dam and powerhouses. 3 of the elevators are in the Pumping/Generating Plant and 2 of them are in the Dam structure. Scheduled completion of this contract is calendar year 2008. A contract was awarded to replace the log booms upstream of the dam. This work was completed in FY2007. The breakers in the 500 kV switchyard are being replaced. By the end of calendar year 2007, 12 of 17 breakers will be replaced with new SF6 gas insulated breakers. |
| Future Planned 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. This project is scheduled for award in FY 2008. The powerplant roofs of the Left, Right, and Third Powerplants will be resurfaced by contract in FY2008. The projects bridge and gantry cranes will be upgraded with new controls and variable frequency drives. This project will begin in FY2008. A recent failure of a single phase transformer on Unit G10 resulted in re-evaluation of the need for replacement transformers. A new set of transformers will be purchased for this unit with a contract to be awarded in calendar year 2008. 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. Specifications will be issued beginning in FY2008. The protective relays for the 500kV and 230kV switchyards will be replaced beginning in FY 2008. This will provide more reliable service between the powerplants and the switchyards and for the power system. The Third Powerplant units are approaching the time for mechanical overhauls. Planning efforts are underway to determine the extent of this work and also to evaluate if increasing the capacity is a technically and economically viable alternative. The 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. |
| 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. BPA has requested an evaluation of the downstream tail water elevation change restrictions in an effort to allow BPA additional flexibility in peaking operations. 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. River operations have been modified to comply with biological opinions and court decisions. The water supply for FY2007 above Grand Coulee was sufficient to provide benefits for endangered species, power supplies, and agricultural growers. |
| River: | Columbia River |
| Plant Type: | Conventional and Pump Generator |
| 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 Third Powerplant Pump-Generator Plant |
1941 1975 1973 |
| Age: | 66 years |
| Net Generation (FY 2006): |
22036.4 GWh |
| Rated Head: | 330 feet |
| Production Mode: | Intermediate |
| Plant Factor (FY 2006): | 37.1 percent |
| Remotely Operated: | No |
Click here for graphs and charts of Grand Coulee Powerplant performance.
Click here for information on Grand Coulee Dam.
Click here for information on the Columbia Basin Project.
Revised October 19, 2007 Hydropower Site Map Help