MP-250014, Beckenried Ischenstollen drainage system, replacement drainage filter construction services

There is a large landslide in the Ischenwald area above Emmetten. To reduce slip activity and debris flows in the front area of ​​the slip mass, the Ischen tunnel was built at the end of the 1970s and expanded at the end of the 1980s. From the tunnel, the drainage filters, which are up to 50 m long, cross the rock and reach into the loose rock layers up to the sliding surface and drain it. Today the slip surface is shifting at a rate of approx. 20 mm per year. The average daily discharge varies from 10 to 80 m/s throughout the year. During a landslide in 1999, almost all of the filter pipes were sheared off and replaced in 2000/2001. Meanwhile, many filter tubes are crushed or sheared off in the area of ​​the sliding surface. Although the drainage capacity is not yet affected, it is likely to decrease in the next few years. The construction project includes the replacement of all drainage filters in the main and extension tunnels; the existing filters will continue to be operated. The filter holes must be carried out in the narrow tunnel between the existing pipes in a rising direction (15-35° from the vertical). Furthermore, concrete repair work on the ridge, in the parament and in the sole as well as work on the existing pipes is planned. Slope water and dirty water must be collected, tested and treated separately. Main quantities: Drilling work approx. 11,400 m Number of filters approx. 353 pieces Solid pipes approx. 3,530 m Filter tubes approx. 7,835 m Repair of shotcrete approx. 15 m3 Repair of concrete approx. 15 m3 Repair of new reprofiling mortar approx. 10,000 kg pore water pressure transmitter approx. 8 pieces. Water discharge measuring points approx. 3 pieces