Underwater applications of prefabricated plugs for maintenance and repairs works at Cheves and Ituango

Low-level outlets and intake facilities at dams typically include upstream water conveyance systems and downstream flow control devices (FCD) such as valves or gates. In many cases, no provision was made in the original project design for isolation upstream of the FCD. Minor works or inspections are possible by divers or remotely operated vehicles, but major works typically require dewatering. This can be achieved by lowering reservoir levels or installing cofferdams, but often this is not feasible or cost-effective in deep waters or where watertight conditions cannot be achieved to manage leakage and create a safe working environment. An alternative solution is to install prefabricated underwater plugs directly upstream of, or within, the water conveyance. This papers reviews two recent examples in Latin America.