SEAMOR Marine discusses the deployment of its Steelhead ROV to inspect the Canadian hydro-electric dam’s water intake trash racks for debris at 27 metre depth and its survival following an extremely dangerous water flow surge.
Situation
In February 2022, the BC Hydro Ladore Dam facility in Campbell River, Vancouver Island, required an urgent intake inspection. At the time, the generators were shut down for maintenance. The trash racks, which protect the water intakes and turbines from debris, were due for inspection.
Problem
The first trash rack was clear of debris. The pilot operator then descended to the bottom and proceeded towards the second intake on the right side at a depth of 27 metres.
The three spill gates, located adjacent to the trash racks, were partially open and spilling water. Because the generators were down for maintenance, the water flow through the gates was extremely high, with the gates open approximately 25cm and 50cm. Due to heavy rainfall, the water flow was higher than normal for that time of year.
Suddenly, the Remotely Operated Vehicle pilot lost the image of the trash racks, and the reel system flew through the air topside about eight feet, jamming itself hard against the railings.
Solution
Despite the powerful forces acting upon it, the SEAMOR Steelhead ROV was still functioning, and the tether remained intact. Two technicians immediately sprang into action, hauling on the tether with all their might. After inching the ROV back inch by inch, the tether finally failed at the vehicle.
The Steelhead ROV then flew out the other side of the dam, fell vertically about 15 metres, and was eventually recovered about 4km downstream.
While accidents like this happen frequently in the industry, there is no such thing as 100% prevention and safety. In this case, the client, BC Hydro, had purchased their first ROV following an injury to a tired diver.
Thankfully, this time it was an injured machine and not a human. SEAMOR is dedicated to keeping divers safer by gradually replacing them with ROVs across the globe, in all conditions and at great depths. While divers may still be required in the future, they will not have to linger at dangerous depths or plunge into potentially dangerous currents without an ROV first ensuring the area is safe to dive.
Read the full case study here, or visit the SEAMOR Marine website to find out more.
