Hibbard Inshore has set the record for the longest flooded tunnel inspection against flow ever attempted.
Success came from using the Saab Seaeye Sabertooth AUV/ROV hybrid. Used as a tethered ROV, which was extremely important to Hibbard for real-time data feedback, vehicle control and safety measures, the Sabertooth swam the 8km of tunnel against a 0.3km/s flow whilst fitted with a range of surveying and filming systems.
This achievement kept the vital water supply flowing to Rio Tinto’s aluminium smelting plant in British Columbia during the inspection mission.
Speed was essential as the flow was reduced during the mission and a ‘very fast’ inspection in an eight-hour timeframe was needed, says Dave Malak, director of Hibbard Inshore.
The Sabertooth was fitted with a combination of multi-beam systems and cameras to provide 3D profiling of the tunnel, along with a record of the tunnel wall status and HD video examination of areas of concern.
For Rio Tinto the 40 year-old tunnel is a critical asset that needed a thorough examination to reveal areas of potential collapse for maintenance planning and to provide comparable data for trends in tunnel condition.
Hibbard’s success follows its record-breaking 24km tunnel inspection inside Australia’s Snowy Mountain hydro scheme where the Sabertooth was also used in its tethered mode.
The Sabertooth concept combines the technologies of both AUV and ROV vehicles into a single unified resource to give operators the range and manoeuvrability of an AUV, yet with the tooling capability of a light-work ROV.
Hibbard Onshore was first to spot the potential of the Sabertooth concept, recognising the advantages of a vehicle that has 360 degree manoeuvrability, a sleek hydro-dynamic design, efficient thrusters and accurate navigation – and an ability to cope with flowing water in a confined space.