The general concept
On March 31, 1999 Wismut delivered first report on the general conception of environmental remediation of Sillamäe tailing pond to the representatives of the government of Estonia and Silmet Grupp.
The remediation concept foresees the following means:
- Reinforcement the dam of the depository by building breakwave on the shore and establishing a pile grillage on the area between the embankment and the shore;
- Blocking the waters, flowing from the mainland by a diaphragm wall;
- Contouring the surface of the depository into a system of shallow valleys with several watersheds and finally covering the depository with a multi-layer waterproof covering;
After remediation the environmental hazards disappear, because:
- The covered depository looks like a hill, covered with vegetation, water can't get in there: it runs down the slopes without absorption; the surface water discharged from the mainland will be led to the other direction by a trench and diaphragm wall;
- Radioactive dust doesn't rise from the covered surface;
- Radon is still emanating from the tailings deposit, but it decays before getting on the surface (half-time of radon is approximately 3,5 days).
- The reinforced concrete pile grillage, established on the shore will guarantee the stability of the dam. The breakwave type of shore reinforcement would be established against weathering wave activity.