ABSTRACT
The A96 motorway from Munich to Lindau skirts Leutkirch for approximately 6 km, through the planned ‘Leutkircher Heide’ water-protection area. As this is the third largest ground-water area in Baden-Wuerttemberg, it calls for special protection. In the approval procedure, the water administration authority imposed conditions regarding the cross-section of the road, the selection of building materials and the control of the pipe system when in operation. Building materials, cross-sectional design and operating conditions are closely inter-related and were given equal consideration. The water administration authority, and the Institute for Soil Mechanics at the University of Munich, as experts, were both involved in the process of decision making. At the same time, details of manufacturers’ current products were obtained. A closed pipe system constructed in cast steel, with geosynthetic clay liners situated under the drainage, was installed. The criteria for the materials were laid down in the usual way for motorway administration: specification, installation instructions and control tests. When going to tender, special tenders for sealing and the pipe system were not excluded. But the specific proposals made could not be accepted. The pipe system and the GCL proved really problem-free in installation. It proved possible to put the plans into practice without any restrictions. For the GCL, the weight, water content, share of montmorillonite minerals and the permeability of the total system were checked.
