Tyrolit Wire Saws Tackle “Underwater Cutting” to Create New Fish Ladder

Published: 15/1

At the Flumenthal power plant in Switzerland, a completely new fish ladder is currently being built in the form of a bypass channel – the ideal construction site for Tyrolit diamond tools and machines. After the construction of the Flumenthal power plant 50 years ago, fish in the Aare were able to overcome the difference in height between the upper and lower water via a fish pass. However, this no longer meets today’s fish migration requirements, which is why Alpiq Hydro Aare AG commissioned a completely new fish ladder in the form of a 1,575-ft (480m) bypass channel, which should be completed by the end of 2024. Within the framework of this project, the old concrete bank wall below the power plant’s estuary had to be removed and replaced by a new one.

For the dismantling work, contractor Bohrex AG from Subingen required a number of core drills and horizontal as well as vertical cuts by wire saw, all of which were carried out with Tyrolit products powered with the PPH40RRP power pack. A diver supervised and supported the underwater work, using a radio and an underwater camera for controlling the cuts. The diver even carried out some of the cutting work with the help of instructions from the team onshore

In a first step, various holes were drilled with Tyrolit core drill bits in order to feed the saw wire for the vertical cuts and to secure and recover the dismantling elements. Half of the drilling was carried out in the dry basin. However, for the second half of the drilling works, the basin was flooded and the drilling was carried out under water. After that, several vertical cuts had to be made with the Tyrolit WCU17 wire saw used together with the attachment kit for the WSE1217 wall saw. The major challenge was the final 82-ft (25m) horizontal cut, which could not be carried out with standard machines due to the required machine power and the enormous cutting length under water. The project team therefore used a special construction in the form of two connected Tyrolit SB wire saws.

The heavily reinforced concrete, loose material, and strong water flow caused by heavy rainfalls made the work a challenge for all parties involved. Safety was also a top priority during the cutting work. Operators were secured by a safety line at all times, while the cut elements were managed to prevent them from being carried away by the current.

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