The Conowingo Hydroelectric Development on the Susquehanna River

The Philadelphia Electric Company, through its subsidiaries, has just completed construction of the Conowingo dam and powerhouse to develop the fall of the Susquehanna River from the tail-race of the Pennsylvania Water and Power Company´s dam at Holtwood, Penna., to a point within four mi. of tidewater. This project ranks as one of the largest hydroelectric developments in the United States and is exceeded in size by the Niagara Falls development only. The speed of its construction, requiring less than two years from the start of construction operations to regular operation of the first units, is an outstanding achievement. In an average year, 1,250,000 kw-hr. will be delivered in Philadelphia at 220,000 volts, from the initial installation of seven 54,000-hp. water-wheel units, (ultimately to be increased to 11 such units), resulting in a saving of more than 750,000 tons of coal annually. These water-wheels and generators, together with the 27-ft. diameter butterfly valves installed as head gates, are the largest from the standpoint of physical dimensions yet constructed. The concrete dam of gravity type, 4630 ft. long, develops a normal head of 89ft., and has created a lake 14 mi. long. The spillway section, 2385 ft. long, has been designed to pass a maximum flood of 880,000 cu. ft. per sec. and is surmounted by movable crest gates for maintaining a constant head-water level. Relocation of 16 mi. of railroad together with many State and County roads and bridges was required in the acquisition of lands for the reservoir.