McMillen Jacobs Associates chose Poseidon P2 seven-foot barges and accessories to float their cranes and materials on a challenging dam project in Montana.
McMillen Jacobs—a San Francisco, Calif.-based engineering, environmental, and construction firm specializing in underground and water resource projects—was retained to design, procure, and install new vertical lift spillway gates at Morony Dam, near Great Falls, Montana.
Morony Dam is a hydroelectric gravity dam located on the Missouri River in Cascade County, Montana that is owned and operated by NorthWestern Energy (NWE). The dam is 883 feet long, 94 feet high and generates 48 megawatts of power. The 390-foot-long spillway consists of nine spillway bays. The original 1929-era radial spillway tainter gates are used to control the flow of water over the spillway. The headrace and powerhouse are located on the north (left) side of the dam.
The existing radial tainter gates are structurally deficient for ice loads and susceptible to ice buildup at the sealing surfaces as well as large ice build up on the horizontal gate surfaces. NWE determined that the most effective solution is to replace the tainter gates with new heated vertical lift roller gates designed to prevent ice buildup on the sealing surfaces and on the gate body. Field services will be performed to incorporate the new vertical lift roller gates into the existing concrete spillway including a continuous 256-foot long hoist structure and building to enclose the hoist mechanical and electrical equipment.
Poseidon Barge, Ltd. is a portable sectional barge manufacturer located in Berne, Ind. The company rents and sells portable sectional barges that are used in bridge construction, general marine construction, dredging and other projects where it’s necessary to float heavy construction equipment, materials or personnel.
Thanks to McMillen Jacobs for their continued support and business!
Reprinted from Marine Construction Magazine, Issue II, 2024
