Tunnel Inspection

Long tunnels are often an integral part of many large hydroelectric dams and aqueduct systems. They present difficult challenges for inspection and maintenance due to their limited access, long penetrations, and typically large diameters. Hibbard Inshore is a world leader in the inspection of fully flooded long tunnels. Eliminating hydrostatic tunnel pressure through dewatering can increase structural stress and the likelihood of failure. In addition, dewatering typically causes increased outage times. Hibbard Inshore eliminates these problems by offering its clients ROV based alternatives. Hibbard Inshore works directly with its customers to design project-specific inspection methods with a focus on reducing the total cost of inspection by minimizing outage times, performing inspections in flow to allow continued generation, and limiting structural and safety risks.

The company has been inspecting tunnels for many years using both ROV and AUV technologies. The latest of these technologies is the hybrid AUV/ROV which combines all of the conveniences of a ROV including real-time data, real-time control, ability to hover to look at areas of interest, and tethered retrieval as a fail-safe. The vehicle also offers the distance and sensor payload capabilities usually associated with AUVs.

Because Hibbard Inshore has a fleet of long range ROVs with varying capabilities, the right system can be selected for each particular project. Sizing the vehicle directly to project needs keeps project costs in line with project requirements.
The fleet of long range vehicles ranges from a small LBV ROV with 2 kilometers of tether to a mid-sized Long Range Navajo with 5 kilometers of tether to Hibbard Inshore’s Saab AUV/ROV with capabilities to over 20 kilometers from a single access point. Each vehicle can be outfitted with cameras, lighting, inertial tracking systems for mapping and alignment along with the latest in single beam and multibeam imaging and dimensioning sonar systems in order to allow for thorough assessment of tunnel surfaces for signs of degradation.