The preliminary construction of Haakoninlahti and Koirasaari was a total contract commissioned by the City of Helsinki, where our professionals were responsible for the dredging, sea filling and excavation in the area as well as the removal of contaminated soil. We expanded the land areas by dredging and filling the sea by a total of approximately 200,000 m³. We deepened the water’s edge of Haakoninlahti by 2,000 m3 (solid cubic volume), of which 800 m3 (solid cubic volume) took place below sea level. In the challenging underwater excavation, we went to a depth of up to 10 metres, so the work required special expertise from planning to implementation.
The contract was carried out as low-emission in accordance with the Carbon Neutral Helsinki 2030 emissions reduction programme, and so only renewable diesel and electricity were used on the worksite. We also promoted environmental friendliness in earthworks: We obtained the quarry needed for fillings in the project from another one of our construction sites, and thereby we reduced the use of virgin materials and the resulting costs.
With the preliminary construction, the land areas in Haakoninlahti and in front of Koirasaari were expanded for the use of housing construction, the new Baneerikuja, boat docks and fixed breakwaters.
The contract time was from October 2022 to June 2023, and the value of the contract was approximately 6 million euros.