Multiconsult is reassessing hydropower plants with underwater ROVs to prevent dam failure

Tuesday, August 16, 2022 / Blueye Office

According to NVE, 625 dams in Norway are vulnerable to increased flooding due to climate change. Over 1,000 bridges have damage of a significant nature that threatens their load-bearing capacity (NRK). A few weeks ago, we also witnessed a bridge collapse in Tretten; fortunately, no lives were taken.

Bridges, dams, hydropower plants, quays, and other similar infrastructure are affected by the sea and weather. They need supervision and follow-up to ensure that the necessary maintenance is carried out. Wearing and damage are quite easily detected on the upper side of these structures, but it's important not to forget the parts located underwater.

Several of Multiconsults engineers carry out annual reassessments of hydropower plants. Ensuring that Norway's hydropower plants are in a safe condition to supply electricity has not become less important with increased prices and the war in Ukraine. It is important to have reassessments carried out to prevent dam failures. We chatted with Anders Tørklep from Multiconsult to learn more about how they use ROVs as part of their service offering to the hydropower plants in Norway.

Both biologists and engineers at Multiconsult use underwater ROVs from Blueye

Multiconsult is a Norwegian engineering and architecture company. With over 3,000 employees in various fields, they offer services in planning, design, environmental studies, project management, and the like.

Since 2019, Multiconsult has enriched its service offering with the Blueye ROV to be able to take pictures and videos during assessments and inspections of underwater objects. Today, ROVs are used by biologists as well for various observations, and engineers put the ROVs to work at dams and hydropower plants. The ROVs enable inspections without draining dam facilities, which is both expensive and time-consuming.

Multiconsult and their Blueye ROV at a hydrodam during winter
Multiconsult and their Blueye ROV at a hydrodam during winter. Photo: Multiconsult

Inspecting hatches, pipes, tunnels, and dam structures when reassessing hydropower plants

In Norway, we have over 1,700 hydropower plants that supply us with electricity. Ensuring that dam structures are in good condition, that the water flow is not obstructed, or that hatches can be maneuvered are just a few areas that require continuous follow-up.

Anders Tørklep is a mechanical engineer who has been with Multiconsult for the past ten years. Anders is out on many different assignments as Multiconsult supports the dam constructor and the power companies with whatever they need.

The tasks using ROVs are usually planned well in advance, as reassessments of power plants are requirements set by the authorities. According to NVE, hydropower plants must be reassessed every 15-20 years.

We use the ROV for many different purposes, especially for inspections. Several of us are approved by NVE to inspect and reassess hydropower plants. If something breaks down at a facility, it can have catastrophic consequences for infrastructure and people. - Anders Tørklep, Engineer at Multiconsult

ROVs are used to check the condition inside pipes and tunnels, but also to see if hatches open and close properly and to check for excavations in the dam structure. With the ROV, they can do this without emptying the dam.

Visual inspection using the Blueye ROV when a hatch is maneuvered. Video: Multiconsult

Before user-friendly ROVs became available, Multiconsult depended on experienced 3rd parties or diving teams.

If it's an underwater inspection job, we have a more competitive offer if we can include our own ROV. - Anders Tørklep, Engineer at Multiconsult

Anders also tells us that around 5 people in his department use the Blueye ROV. It is essential for Multiconsult that more people know how to use the tool. As they work on multiple projects at once, sending more people than necessary to a project is unfortunate.

The Blueye ROV is easy to use. Low threshold. Intuitive. - Anders Tørklep, Engineer at Multiconsult

Climate change puts pressure on dam safety

NVE classifies dam facilities in Norway in classes of consequence from 0 to 4. The various classifications are set based on the consequences a dam failure can have for property, people, infrastructure, and the environment. Class 4 is the most serious, and in class 0, there are no consequences.

Imagine that the dam bursts and a cabin is located below. You then have to assess whether the wave from the burst hits the cabin or not. If you assess the water to reach the cabin, then the dam belongs to consequence class 1. - NVE

The consequence classes are used to differentiate requirements for security, internal control, competence, and other technical requirements.

Osfaldet powerplant after a breach in 1916
Osfaldet powerplant after a breach in 1916. Photo: Odd Daane / Norsk skogmuseum

In 1791, 22 people lost their lives due to a dam failure at Kobberdammen in Trondheim, just a few kilometers from where Blueye's office is today. This is the worst dam failure in Norway's history (NVE). Fortunately, we have not experienced any dam failures in modern times in Norway. Still, there are reasons enough to be aware of the greater vulnerability to increased floods due to climate change. NVE has counted 565 dams in classes 3 and 4 in a recent analysis (2021) and out of those, 45% are vulnerable to increased floods.

Although dam safety is generally good, future climate change may put more pressure on dams as they will have to withstand greater floods and thus greater loads than they do today. - Lars Grøttå, Section Manager for Dam Safety in NVE

Would you like to learn more about using ROVs in hydropower? Feel free to contact us by filling in the form below.

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