Excavation of Blominmäki wastewater treatment plant to pick up speed during the spring

The work on HSY's new wastewater treatment plant in Espoo's Blominmäki district was about five per cent complete as of January 2016, but the excavation of the bedrock will pick up speed during the spring. The excavation will proceed at maximum speed with 5–6 drilling jumbos once the Blominmäki access tunnel is built to provide access to the treatment plant's underground cave level and the connection between Mikkelänkallio and Blominmäki is opened for use.

The construction of the Blominmäki wastewater treatment plant was celebrated on 20 January 2016 in one of the plant's process halls, which will be 20 metres wide. In time, these post-filtering halls will be where the plant achieves its lofty treatment targets: more than 90% of nitrogen and more than 96% of phosphorus will be removed from the wastewater treated at the plant.

"The Blominmäki plant will achieve by far the best wastewater treatment results in Finland and the entire Baltic Sea region. It will also be the most energy-efficient treatment plant in Finland, and perhaps all of Europe. At HSY, we are also prepared to implement even more advanced technology in the future. For example, at the similar wastewater treatment plant in Helsinki's Viikinmäki district, we are currently investigating the capture of phosphorus and nitrogen nutrients directly from the treatment process," says Raimo Inkinen, Executive Director of Helsinki Region Environmental Services Authority.

"Lemminkäinen has extensive experience of complex rock engineering. Our excavation projects include the recently completed Oulun Kivisydän parking facility and the Rantaväylä tunnel in Tampere. The experiences we gained from these projects will be utilised at Blominmäki. We are placing particular focus on carrying out the excavation work efficiently with minimal disturbance to the environment and local residents," says Harri Kailasalo, Executive Vice President, Infra projects at Lemminkäinen.

According to Jukka Mäkelä, Mayor of Espoo, the wastewater treatment plant is a good example of cooperation across municipal boundaries.

"Built in bedrock in Espoo, the plant will treat wastewater not only from Espoo and Kauniainen, but also from Kirkkonummi, Siuntio, western Vantaa and possibly Vihti. The plant is centrally located with respect to the future urban structure. Relocating the wastewater treatment plant from Suomenoja to Blominmäki supports the development of the Finnoo area and the entire West Metro growth corridor. The area around the West Metro will feature urban structures supported by the new railway, diverse housing, smart traffic systems and the best environment for innovation in all of Europe," Jukka Mäkelä says.

The construction of the wastewater treatment plant began in December 2014 with the Mikkelänkallio vehicle access tunnel, which the contractor, Skanska, excavated over a length of approximately one kilometre. It was immediately followed by Lemminkäinen's rock engineering contract, which will continue until January 2018. The wastewater treatment plant will be commissioned in 2020.

Blominmäki project website: www.hsy.fi/blominmaki