ASI Group

Construction of Dam Diversion Tunnels

ASI was approached by a hydroelectric company regarding support for the closure of diversion tunnels for a dam under construction. Previous attempts by other inspection/survey companies resulting in failure to collect any data in the “No Go” zone near the intake. Our current unmanned survey vessel, however, was not designed to withstand the strong river flows near the intake, which reached several meters per second. 

To overcome this challenge, ASI took the initiative to construct a custom pontoon frame that could be integrated with the unmanned survey vessel’s computer and positioning systems. This innovative solution enabled us to create a robust Unmanned Surface Vessel (USV) capable of withstanding the high flows. 

During the design process, it was crucial to incorporate multiple safety factors to prevent the unit from being pulled into the tunnel and potentially causing damage to the infrastructure. ASI implemented a redundant system using two air winches in tandem, ensuring a 100% backup mechanism. Even in the event of a full winch failure, the system would remain operational. 

Additionally, two jet boats were employed to provide support for the launch, recovery, and redirection of the USV. Each air winch required nearly 3,280 feet (1,000 meters) of rope in the water for operation. ASI was successful in collecting data and identified several points of interest for the client.