Finland. Tampereen seudun keskuspuhdistamo Oy
| Date of agreement: | 07 Nov 2019 |
|---|---|
| Country: | Finland |
| Customer: | Tampereen seudun keskuspuhdistamo Oy |
| Amount in EUR: | EUR 150 million |
| Maturity: | 30 years |
| NACE sector / loan type: | Collection, purification and distribution of water |
This loan has a positive effect on maritime environments: 100%
Project
NIB is providing the loan facility for Tampereen Seudun Keskuspuhdistamo (Tampere Region Central Treatment Plant) to safeguard the treatment of sewage in the Pirkanmaa region far into the future.
The wastewater treatment plant (WWTP) will be built in the Sulkavuori bedrock. The purified effluent will pass through the bedrock tunnel from Sulkavuori to Vihilahti area and further along the discharge pipeline to Lake Pyhäjärvi. The discharge line changes from a bedrock tunnel to a water-installed pipeline in Vihilahti. The pipeline will be installed in the bottom of the lake partially through excavation and partially through descent. The drainage lines from the direction of Rahola, Pirkkala and Lempäälä are mostly designed for street and road areas and waterways.
The centralised wastewater treatment solution is utilising the latest technologies. The WWPT will be an active sludge plant operating on a parallel precipitating principle, where the wastewater is cleaned mechanically, chemically and biologically. The purified effluent will be disinfected by UV treatment.
The project will reduce the effluent load on Lake Pyhäjärvi. In addition, the project will improve the sanitary condition of the Lake Pyhäjärvi and the water system below it.
The construction work at Sulkavuori has commenced, and the wastewater treatment plant is expected to begin operations in 2024. In addition to freeing areas for residential development, the central treatment plant will handle sewage from industry and service industries.
The existing WWTPs at Viinikkala and Rahola in Tampere as well as in Lempäälä will be closed. All three existing plants are located in the middle of residential areas in valuable waterfront areas. Closing the plants will enable the vacated land areas in Tampere and Lempäälä to be redeveloped in a way considered to be a viable and sustainable utilisation of municipal resources.
The central WWTP is a joint venture between the municipalities of Kangasala, Lempäälä, Pirkkala, Tampere, Vesilahti and Ylöjärven Vesi Oy.
Fulfilment of NIB's mandate
The treatment capacity, or average sewage flow, will increase by 19% between the years 2014–2040, and will accommodate the expected population growth of Tampere and adjacent towns.
A well-functioning wastewater collection and treatment system together with utilisation of the wastewater treatment sludge form a necessary component of a sustainable society. Centralised systems are most efficient, as they tend to be more flexible and better controlled. With the expanded wastewater treatment capacity, the wastewater treatment plant will be able to capture more overflow water and reduce the amount of nutrients entering the water system.
The existing plants are unable to improve their processes to achieve sufficiently high levels of nitrogen removal and the treatment efficiencies are not fully in line with HELCOM recommendations, thus the centralised treatment plant will improve the existing situation.
Sustainability summary
This is a project with a potentially extensive environmental and/or social impact (category A, read more)
The new WWTP in Sulkavuori will replace three plants in and around Tampere, which were constructed in the 1960s and 1970s. The existing facilities are at the end of their technical lifetimes. The new wastewater treatment unit is being built underground in caverns to be excavated for this purpose.
The key environmental issues of the project include noise and vibration impacts during construction, wastewater effluent discharge into the Lake Pyhäjärvi, and odorous emissions. The noisiest phase of the project is the excavation of caverns and tunnels by drilling and blasting.
As mitigation efforts, the project will install noise barriers and will limit the construction time. The odorous emissions will be reduced significantly, as the centrally located facilities will be moved to Sulkavuori. Building a WWTP in underground caverns and treating the odorous emissions reduces the odour impact on the environment.
The new WWTP will reduce the nutrient load to Lake Pyhäjärvi and its downstream waters. The phosphorous removal is more efficient than in the existing wastewater treatment plants and the phosphorous load on Lake Pyhäjärvi will be reduced by 600 kg annually.
The two current WWTPs lack an efficient nitrogen removal and the new Sulkavuori facility can reduce significantly the nitrogen load on Lake Pyhäjärvi by 1250 tonnes annually. The longer retention time in the aeration basins and the additional sand filters make the wastewater treatment more efficient.
The new WWTP is also to disinfect the water before its discharge into Lake Pyhäjärvi.
