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STABLE (LIFE06 ENV/FIN/000195) is a LIFE-Environment project "Controlled Treatment of TBT-Contaminated Dredged Sediments for the Beneficial Use in Infrastructure Applications. Case: Aurajoki – Turku, Finland". STABLE has been testing and demonstrating innovative, new methods for the treatment of contaminated sediments: dredging with an environmental grab and stabilisation with the new process stabilisation system. The project involved two real scale tests in Port of Turku: a smaller field test of the methods during 2007 and, after improvements and further development of the equipment, a whole-scale pilot during 2008-2009. The stabilised masses are used for the foundation of a container storage area.
The project started on 1st April 2006 and was finished at the end of March 2009.
The results are presented in Layman's report and other publications of the project. The project has shown that
- dredging with environmental grab does not cause significant turbidity in the water environment. Additionally, the water content of the dredged sediment is relatively low and that makes it possible to stabilise the dredged sediment without separate dewatering.
- the new process stabilisation system produces homogeneous mixtures of binder and the dredged sediment. For this reason it has been possible to obtain savings in binder and achieve even stabilisation of the mixture in the stabilisation lagoon.
- the binder admixture is a critical factor with respect to the technical quality, economy and environmental impacts of the stabilisation. The optimisation of the binder recipe requires quite extensive laboratory tests and creativity to acquire new types of binder components like by-products from power stations and industry of the region.
- the cost efficiency of process stabilisation largely depends on the feeding efficiency of the dredged sediment from barges to the process stabilisation equipment and requires relatively large total amount of masses to be treated
- the combined use of environmental grab and process stabilisation system consumes less non-renewable natural resources and energy than available alternatives. The theoretically alternative systems are e.g. the use of normal grab for dredging, mass stabilisation instead of process stabilisation, or even natural aggregates for the filling of the lagoon instead of stabilised dredged sediment. The latter case involves dumping of the contaminated dredged sediment into landfills.
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