The new Näckenbadet is being built on the same site where a previous indoor swimming facility was located. The difference is that the new one will have a basement underneath the pools, thus placing the facility below the groundwater level, which classifies the work as "Water Operations" according to the Environmental Code.

Background

The demolition work began in August 2022, and in December of the same year, a permit for water operations was granted by the Land and Environment Court. Peab Anläggning AB was contracted to build the new facility.

Nacka Municipality informed early on about the site's history and the old landfill that had been there. In the 1930s-60s, the inner part of Neglingeviken was filled in, probably with demolition debris, and due to the moraine in the area, there are conditions for near-shore landslides. A soil environmental investigation was conducted when the old Näckenbadet was built, and the groundwater was sampled again in 2017, showing a slight tendency for leaching. In Nacka Municipality's waste plan 2020-2024, Näckenbadet was listed as a priority along with eight other closed landfills.

First of all, a geotechnical investigation was conducted, which resulted in the choice of "Jet Grouting" or cement injection as the method to stabilize the ground and seal the sheet piles around the area where the excavation would be done.

Properly sized water treatment from the start

Initially, the plan was to start the project with just a sedimentation container, but Robert Mena, now project manager at Peab Anläggning AB, soon explained the benefits of investing in a full-scale system from the beginning.

– We gathered for a brainstorming meeting at the municipality, and it didn't take long before they understood the advantages of investing in a larger system, says Henrik Larsson, project manager at Swedish Hydro Solutions.

– Both we and Peab have extensive experience with such projects, and when we showed the benefits of avoiding all the interruptions that an undersized system would cause, they understood immediately.

Said and done. The plans for a full-scale water treatment system were submitted to Nacka Municipality immediately, as the site where it would be constructed was subject to surface load requirements - which requires a special permit.

Quick procurement and solution-oriented dialogue

– Once the design was decided, the procurement happened very quickly, right in the middle of summer 2023, says Carl-William Kalholm, Sales and Marketing Manager at Swedish Hydro Solutions. We met Peab on-site several times to discuss the setup and brainstorm ideas to find the most effective solution.

– We have a very good collaboration, and we have found several creative solutions together. For example, the old pools were initially used as pre-sedimentation steps to quickly start the work, continues Carl-William.

Focus on groundwater

Once the sealing sheet piles were established and excavation work began, the focus shifted to groundwater management and protecting the sensitive recipient Neglingeviken.

When digging to a certain depth, groundwater starts to push up. When this occurs, a completely different set of regulations come into play. There are clear rules for how much groundwater can be pumped out and treated. If this limit is exceeded, groundwater from surrounding areas can move in, reducing the bearing capacity in the areas the groundwater leaves.

– According to the regulations, we are not allowed to pump out and treat more than 3,000 cubic meters of water, says Angelica Lüth. That is our upper limit, and we have an environmental consultant from Nacka Municipality who closely monitors how we manage the groundwater and ensures we adhere to the programs in place.

Good cooperation

The project has consistently been characterized by good communication and a solution-oriented approach. Swedish Hydro Solutions, together with Peab Anläggning AB and Nacka Municipality, has maintained a clear environmental focus.

"We have learned a lot from this project. We have all become a bit of water treatment experts, laughs Angelica Lüth. Swedish Hydro Solutions has shown us how to manage the facility, and we have learned a lot about water management, sampling, and its importance, she concludes.

– This is an important project, and Neglingeviken is a sensitive recipient. Whenever something unexpected has occurred, we have been on-site within an hour or two. Everyone prioritizes both good cooperation and environmental issues, concludes Carl-William Kalholm.

The new Näckenbadet is expected to be ready for occupancy in 2026.