The periodical Suomen Kuvalehti has published an article about the environmental impacts of the planned construction at Malmi Airport. Due to the quality of the ground, the area should be piled densely. The article estimates the carbon dioxide emissions of piling: more than 350.000 tonnes of carbon dioxide is produced in pile manufacturing alone, plus the greenhouse gas emissions from pile assembly and cleaning the area. The cost of piling is estimated at EUR 470 per square meter. This would increase, for example, the price of a 100 m2 (1076 sq ft) family home by €47.000.
The information is based on the constructability survey carried out by the city, and the officials confirm it.
You can read the article (in Finnish) here.
Constructability survey by Destia, 2015 (in Finnish)
A preliminary study of acid sulphate soils mapping techniques, Ramboll 2018 (in Finnish)