Terramare deepened the Vuosaari fairway and harbour basin from 11 metres to 13 metres navigation depth in 2020-2021. The project involved the dredging of around one million cubic metres of clay and moraine material, and around half a million cubic metres of bedrock was drilled and blasted, says Project Manager Jani Vyyryläinen.
“The project was challenging in the sense that there is a lot of sea traffic at the location and different parties were involved. We frequently held meetings to ensure that information flowed freely about what was happening and where,” explains Vyyryläinen, reminding us that safety was the number one priority in the project.
Blasted rock for re-use
In the contract, the soft materials generated were disposed of in a dumping area in the open sea, while the blasted rock was transported by barge by sea for use in sea-filling in the construction of the new Hernesaari district. Another blasted rock disposal location was Ruusuniemi.
“Sea transport of the blasted rock not only brought cost savings, but also reduced noise and traffic disruption in the urban area,” says Vyyryläinen.
The upgraded, deeper fairway and harbour basin helps Vuosaari Harbour to meet the challenge set by growing ship sizes. For some container vessels, cargo capacity may be almost doubled, which in turn will bring savings in transport costs and reduce the environmental impact of shipping traffic.
Reins tightly in own hands
According to Vyyryläinen, the project represented Terramare’s core expertise, but it also had its own special features: for example, a small local marina and some power plant seawater intakes must be taken into account at the various stages of the contract. And there were also the fragments of an old stern door that needed to be cleared from the seabed.
“Coordination was needed over a fairly wide area, because sometimes we operated as far as 20 kilometres out at sea.”
As part of the dredging and the drilling and blasting work, various navigation aids have also been moved in the harbour basin and fairway area.