Monitors the sea for Jotun in Sandefjord

Jotun is carrying out environmental clean-up work on the Vera site in Sandefjord. 100 years of industrial activity have left their mark. Cautus Geo is monitoring the fjord in real time to prevent the spread of heavy metals and oil.

Jotun has assessed future risks. The company has owned the Vera site since the 1930s. The concern is that climate change, bringing more rain and more frequent storm surges, could lead to the leaching of environmental pollutants.

– A new climate, characterised by more extreme weather as a result of rising temperatures, rising sea levels and torrential rain, leads to less predictability. This can increase the risk of leaching. Pollutants below sea level could then be washed away. We want to prevent that. That is why we are cleaning up after past activities, says project owner Jan Helge Eriksen at Jotun.

The cost of the project could exceed 200 million kroner. The 77 mål industrial site down by the sea is to be cleaned up and brought into line with the requirements for sensitive land use, such as residential development.

Underwater excavation

A total of 55,000 cubic metres of contaminated soil is to be removed. The work is being carried out by the contractor AF Decom. Some of the excavation is taking place below sea level, right next to the water’s edge.

Physical barriers and silt curtains are used to protect the fjord. Offshore, Cautus Geo monitors water quality using solar-powered monitoring buoys.

The sensors continuously measure turbidity and send the data to Cautus Web. “If the set thresholds are exceeded, an alarm is triggered via text message and email,” says project manager Anders Brekkenes of Cautus Geo.

High complexity

– It’s a large and very complex project with a great deal of variation in the ground. Ongoing monitoring is an agreed part of the arrangement with the Norwegian Environment Agency. Cautus Web gives us the overview and peace of mind we need, says environmental adviser Ida Nilsson at AF Decom.

The summer season in nutrient-rich waters has presented practical challenges.

– We’ve had a lot of fouling on the sensors in the sea. This has resulted in strange readings in the measurement data. We’ve taken various measures, including replacing sensors, cleaning them, applying copper tape and carrying out visual inspections, says Nilsson.

The consultancy firm Norconsult has engaged Cautus Geo to provide sensor services. They highlight the Cautus Web analytics solution.

– “The portal is easy to understand and simple to use. It’s a great asset in projects like this,” says project manager Halvor Saunes of Norconsult.

Ready for the future

Once the work is completed, the previously decommissioned industrial site will be free of contamination. It will then be able to withstand future climate conditions and future uses, even if this involves housing with playgrounds and shops.

– No decisions have been made regarding its future use. However, we would like to open up the area. This would allow a coastal path to be established, and the site could perhaps, in the long term, be developed with homes and shops, or used for our own purposes, new industry or expansion, explains Eriksen.

“Our job is to provide expert support on technology and ensure real-time monitoring of environmental parameters,” says Brekkenes.

Delivery at a glance

• Sensors: Buoy-based turbidity gauges at a silt curtain in the sea (one measuring buoy and one reference buoy).
• Web portal: Cautus Web – a cloud-based real-time platform with alarm notifications via email and SMS.
• Key players: Jotun (developer), AF Decom (main contractor), Norconsult (consultant) and Cautus Geo (environmental monitoring).