The holding dam had to be resealed using a new bored pile wall which was strengthened at the top and bottom with two reinforced concrete belts. To excavate recesses in the bored pile wall to attach the latter, Umwelttechnik & Wasserbau GmbH used a 24t excavator with a Kemroc ‘KRX 70’ power tool drive unit with longitudinal milling attachment.

Umwelttechnik & Wasserbau GmbH is currently involved in an extensive project in the Harz Mountains. Near Osterode, a holding dam within the Söse dam network is to be completely renovated, primarily to secure the drinking water supply from the reservoir on the river Söse, and secondly, to protect the main dam from the consequences of extreme weather events. The project also includes renovating federal highway 498 which passes over the holding dam and the construction of a new road bridge over the weir. 

As part of the Sösetal reservoir, there is a holding dam located in front of the actual main dam. During renovation, the holding dam will have a completely new sealing diaphragm installed in its core in the form of a bored pile wall. The bored piles are made with a water impermeable grade of concrete to seal the dam. For this purpose, the wall will consist of bored piles up to 25m long and around 120cm diameter. To fasten the reinforced concrete belt to the wall, a recess is made in each pile, into which an anchoring spur is installed. To make the recesses for the anchoring spurs in the piles, U&W used its 24t excavator with a Kemroc power tool KRX 70 drive with a longitudinal milling attachment.

Most of the various grinder attachments that the engineers at U&W have available in their tool inventory are supplied by Kemroc. “Working with excavators and milling attachments is a natural part of our everyday work,” says Johannes Frankenfeld, site manager for the project. “Of course we don’t have to have every type and size of milling attachment in stock for every conceivable application. For this very specific application on the bored pile wall, the tool of choice was a KRX 70 drive unit fitted with a milling head, and this is what we rented from our Kemroc dealer for this project.”

Work on the large scale project was scheduled to run from April 2022 to summer 2025. By late autumn 2023, the first concrete anchors on the upper side of the dam were completed. Work on the remaining concrete anchors is expected to continue until the summer of 2024.