Powerhouse Bridge Crane Rehab, Fort Randall Dam, South Dakota

The project at Fort Randall Dam was approached with incredible foresight. When the project specification was released, it was assumed that the rehabilitation would be completed on-site at Fort Randall Dam. In an effort to decrease disruptions to the powerhouse workflow, we developed a plan to remove the cranes from the building and perform as much work as possible at the WEMCO facility in Spokane, WA. One of the obstacles that we faced was getting the cranes in and out of the building safely. When the cranes were originally installed, building access was no issue. After the original installation in the 1950s, a narrow roll-up door was installed at the facility. During disassembly and reinstallation, the trolleys had to be positioned on their side in order to fit through the door.

WEMCO was hired as a Prime Contractor by the US Army Corps of Engineers to be responsible for performing a complete mechanical and electrical rehabilitation on two 150-ton capacity Powerhouse cranes, as well as up-rate their capacity to 155-tons. The rehabilitation scope included engineering and manufacturing a new control system. Inspecting and rehabilitating mechanical components including all-new open gearing, bridge driveshaft, gearboxes, main and aux bull gears, new paint, new wire rope as well as a new Operator’s Cab complete with HMI display and modern technology to make the crane operation more user-friendly, reliable, and safe. WEMCO was also required to up-rate the current 150-ton powerhouse cranes to 155-ton capacity for lifting heavier components when servicing the generators. This required an in-depth FEA stress analysis of the hoist trolley, and adding additional stiffeners and bracing was to make the existing trolley rate for 155-ton capacity with the appropriate amount of safety factor. WEMCO removed the Cranes from the dam and transported them back to Spokane, WA for a full inspection and rehabilitation procedure. In-house setup and functional run testing were performed at WEMCO headquarters for customer acceptance before reinstallation taking place. Once the Cranes are reinstalled, a final load test will be administered by a Commissioning Engineer and the USACE will be trained on the safe operating procedures for their new equipment. When these cranes are operated in tandem at max capacity, this results in a 310-ton lift.

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