User:HomerPaq/Hinged floating bulkhead

Developed in 1987 by engineers from Xcel Energy and Ayres Associates, an architectural/engineering firm based in Eau Claire, Wisconsin, the hinged floating bulkhead has become a valuable tool to dewater gates and intakes of dams and hydroelectric plants. Since its initial development, the innovative system has been used at projects across the nation to safely, efficiently, and cost-effectively dewater spillway gates and powerhouse intakes.

This dewatering system significantly reduces owners' costs, provides a safe work environment, and efficiently uses resources. The system has been particularly valuable in dewatering tainter gates for rehabilitation and testing. The bulkhead caissons can be launched from shore, floated to the structure, and quickly installed.

Older floating bulkheads were typically one-piece bulkheads used at site-specific intakes. Many of these bulkheads are still in use, but they are difficult to maneuver and operate, cost more than conventional bulkheads, and are expensive to maintain. The hinged floating bulkhead is composed of individual floating caissons pinned together at hinges. To place the floating bulkhead, the lower caissons are filled with water to sink the unit into place. Small electric hoists or crane can be used to position the submerged bulkhead against the pier nose. The bulkhead operates much like an overhead garage door for sealing an intake.

The bulkhead's buoyancy is such that only a small percentage of the bulkhead's actual weight rests on the intake's or spillway’s sill. Once the bulkhead is in place at the bay, the existing gate is opened to dewater the bay. The reservoir water pressure keeps the bulkhead in place and seals it to the pier noses.

To remove the bulkhead, the water-filled caissons are filled with air, and the unit floats away from the pier nose. The bulkhead assembly is then ready for use at the next bay.

The floating bulkhead is typically placed in the water with a small crane. It can be positioned against the pier nose with or without a crane. Installation can also be done with or without divers, depending on the application.

The design won a national award from the American Consulting Engineers Council (now American Council of Engineering Companies) for its innovation and cost-effectiveness. It also won a Wonders of Wisconsin Engineering Award in 2007 from the American Council of Engineering Companies, Wisconsin Chapter.