Jämsä water treatment plant

NYAB constructed the expansion part of the Jämsä central treatment plant and managed the structural works for the renovation of the old treatment plant, as well as the full delivery of the machinery contract. The project was extensive and demanding, lasting nearly a year and a half. NYAB successfully completed all the work three months ahead of schedule.

The Jämsä central treatment plant serves around 15,000 residents in Jämsä and Jämsänkoski, and during the peak season of the nearby Himos ski resort, the population multiplies. For instance, during the midsummer festivals, Himos hosts 40,000 visitors. This must be accounted for in the plant’s capacity.

The main reason for the extensive renovation work and the construction of the new process building was due to environmental permit requirements.

“Ammonium nitrogen must be removed from the wastewater, which our old system couldn’t handle. So, we built a system that meets the latest requirements in the new treatment plant, and at the same time, renovated the old part: among other things, we added a new screening unit and replaced the aerators,” explains Pekka Karppinen, the waterworks manager of the Jämsä central treatment plant.

NYAB handled all the earthworks, machinery installation, and the construction of the new process plant building. The work began in February 2020 and was scheduled to be completed by the end of September 2021, but everything was ready by June, three months ahead of time.

“Everything went surprisingly smoothly, really effortlesly, even though there was a lot of organizing with the main contractor NYAB, along with process automation, HVAC, and electrical contractors all working on both renovation and new construction sites at the same time. NYAB planned and scheduled everything so that the work flowed very smoothly. It was clear that experienced professionals, used to working together, were on the job,” Karppinen describes the project’s progress.

The plant remained operational throughout the project

NYAB’s project manager Pekka Nissinen says the project began with the earthworks for the new process building and then continued with the construction of above-ground elements, including the casting of concrete tanks on-site.

“The concrete tanks are 60 meters long, 15 meters wide, and about four meters deep. The tanks were divided by partitions into two primary settling tanks and two aeration tanks. We built concrete vault structures on top of them and the process building. At the same time, we worked on the renovation of the adjacent old treatment plant.”

The renovation works for the old plant had to be carefully scheduled around Himos’ peak season to minimize disruption during critical upgrade phases.

“When we upgraded the machinery in the old wastewater treatment plant, it had to remain operational at all times, which added a layer of complexity to ensure that the water treatment process wasn’t interrupted. This was done by alternating the renovation work between the different tanks. Out of two aeration and two settling tanks, one was always in operation,” Nissinen explains.

When the work was completed in June, test runs were conducted without any issues and according to the plans.

Karppinen is pleased: “The plant works as it should, and ammonium nitrogen is being removed. We are now fully compliant with the new environmental permit requirements.”