Eranti Engineering Oy

Innovative solutions

Our environmental engineering work stars with defining the problem and understanding the fundamentals. The challenge is to find a cost efficient solution that does not create greater problems than it solves. It is important to put the project into the right track from the very beginning.

The renovation project of lake Gallträsk is a good example. The city of Kauniainen had spent decades and hundreds of thousands euros to figure out how to dredge the lake that had become shallow because of sedimentation. It was focusing on a method of dredging the sediment an mixing it with turf and nutrients. The mixture was then supposed to be transported to farms for land improvement in accordance to the ideology of sustainable development.

There were three problems:
1) The cost of this renovation scheme was huge;
2) The scheme would require setting up a wet process and traffic of hundreds of heavy trucks at the heart of the city;
3) A major portion of the sediment was water and using fossil fuel to transport water is not in accordance with sustainable development.

The key issue in solving the problem was to notice that the water content of the sediment was in excess of 1000 %, ie. the weight of water is more than ten times the weight solid substance in the sediment. When such sediment is put under pressure, it squeezes like a sponge. When it is dried up, it shrinks to a small fraction of its original volume.

Eranti Engineering Oy costestimated a scheme, where sediment is dredged into a sheetpile retained island. Since the volume of the island is only some 20 % of the original volume of the sediment, there would be no need to process or transport material. The cost is also only a fraction of the original estimate.

Other break trough solutions by Eranti Engineering include use of thermal effluents for ice control to achieve year round navigation at the Saimaa Channel and methods to deal with sediments polluted by dioxins and furans at the River Kymi.

Lack of oxygen in bottom causes euthropication of the Gulf of Finland because of the internal loading of phosphorus. Air bubbling is a cost efficient way to eliminate this internal loading.