Grand Coulee Bridge by two concrete piers, about 150 ft high. During construction, one of the piers began to tilt, probably due to fine glacial material under the gravel. Additional supports were added as a temporary measure. The piers were later taken down to the bedrock using pneumatic caissons. Grand Coulee Bridge The Grand Coulee Bridge, or Columbia River Bridge at Grand Coulee Dam, is a steel thru cantilever truss bridge built in 1934-1935. It carries Washington State Route 155 across the Columbia River immediately below Grand Coulee Dam, near the city of Grand Coulee, Washington. It was added to the National Register
Grand Coulee Dam of electricity. Each generator is supplied with water by an individual penstock. The largest of these feed the Third Powerplant and are in diameter and can supply up to . The dam's power facilities originally had an installed capacity of 1,974 MW but expansions and upgrades have increased generation to 6,809 MW installed, 7,079 MW maximum. Grand Coulee Dam generates 21 TWh of electricity annually. This means the dam generates about 2,397 MW of power on average, which results in a total plant factor efficiency of 35%. In 2014, 20.24 TWh of electricity was generated. Grand Coulee Dam's spillway is