Riverbed lining of the Glan

Situation

For the construction of the new Klagenfurt Regional Hospital, it was necessary to divert the Glan river over 850 m in order to create a new area of 6 hectares. However, there were two problems with the construction project: the new riverbed lies partly in the groundwater, but a rise in the groundwater level and mixing of groundwater and river water must be avoided. Secondly, tree and plant growth must be possible in the area above the waterline.

Solution

For these reasons, the planners opted for a geosynthetic clay liner. This meets both on-site requirements. It provides the necessary seal between the river water and groundwater, whilst above the waterline, the root systems of trees and shrubs can penetrate the liner. Bentonite powder is used as the sealing material in the geosynthetic clay liner. The bentonite powder has excellent swelling properties. If a root pierces the membrane, the swelling clay envelops the root system and thus largely retains its sealing properties. The special ability of the GTD even extends to the point where piles can be driven into the ground, whereby – in this extreme case – one can assume that the driven piles will be sealed. The overlaps of the waterproofing membranes are bonded using a special adhesive to provide shear and tensile strength. On the one hand, this ensures the necessary waterproofing of the overlaps. On the other hand, it prevents the overlap areas from shifting, e.g. due to heavy construction machinery.

Advantages

• Natural design of the entire site
• Good swelling properties of the clay waterproofing membrane
• Separation of groundwater and river water