ASI Group

Underwater Inspections of Rock Cut Tunnels

ASI was hired by a client to inspect two rock cut tunnels at a Generating Station. The purpose of the inspections was to gather data for the client’s condition assessment of the tunnels under full hydraulic head pressure, unlike previous inspections that were done with manned entry in a dewatered state.

ASI chose to utilize their Seaeye Falcon ROV (Remotely Operated Vehicle) due to its capabilities and compact size. The ROV was equipped with various sensors and tools to carry out the inspections effectively. These included a video camera, real-time imaging sonar, multi-beam profiling sonar, inertial navigation system with an integrated doppler velocity log (DVL), and a lighting system. The Falcon ROV’s design allowed it to operate over long tether lengths, and its four horizontal vectored thrusters enabled it to move in forward, lateral, and reverse directions.

The first tunnel inspection covered a total distance of 9,619 feet (2,930 meters), while the second tunnel inspection spanned 11,889 feet (3,620 meters).

By conducting the inspections using the ROV, ASI achieved several advantages. Firstly, they minimized risks to personnel and equipment since there was no need for manned entry or dewatering the tunnels. This eliminated the potential dangers associated with the pressure differential and reduced the risk of collapse. Additionally, the inspections were completed safely and within the specified timeframe.

Overall, ASI successfully performed underwater inspections of the rock cut tunnels using their Seaeye Falcon ROV, providing the client with the necessary data for condition assessment without compromising safety or operational efficiency.