KEMROC Combos Deliver High-Accuracy Performance for High-End Development

Published: 24/7

Königsteiner Höfe is the exclusive address of an innovative residential and commercial quarter which is being built in Königstein, Germany. The 97,000 ft2 (9,000 m2) project includes eight luxury apartment buildings, as well as offices, a bistro, and organic market. The general contractor Köster and the subcontractor Höfling Erdbau have started the first phase of this ambitious project which has to be completed by June 2024. This phase involves excavating the site and installing all the required ground support.

After the groundbreaking ceremony at the end of December 2022, subcontractor Höfling Erdbau excavated 700,000 ft2 (65,000 m3) construction site 50 ft (15m) deep on the slope side, and to 23 ft (7m on the valley side, with shoring erected as a contiguous bored pile wall.

By mid-February 2023, nearly 190 bored piles surrounding the excavation pit were completed. The piles then had to be anchored and lined by filling the space between each pile with steel mesh and shotcrete. To keep costs down, the shoring wall had to be profiled back beforehand with a surface to be as flat as possible. Achieving the surface finish required would have been impossible in the difficult quartzite ground conditions using an excavator with breaker or ripper.

To complete this task, Höfling Erdbau combined a 25t excavator with a 161-hp (120kW) KEMROC KR 120 rotary drum cutter. This made it possible to mill the ground containing quartzite from between the bored piles with a smooth surface finish and line it with shotcrete in what would have previously been classed as soil class 6 to 7 material.

 

Drainage trenches all around

Subsequently, Höfling Erdbau had to excavate a drainage trench up to 23.6 (60cm) deep and 19.7 in (50cm) wide along the entire length of the shored wall. Here, the solution was the combination of a 9t short-tail excavator and a 59-hp (44kW) KEMROC EK 40 chain cutter.

The unique design of the KEMROC EK range of chain loosen the material along the entire width of the cutter head without leaving a central spur as would be the case when using conventional drum cutter without any sideways movement. In this way, they excavate trenches with a precisely defined width. This operating characteristic saves time and up to 40% energy, is gentle on excavators and produces fine-grained milled material that can often be used immediately as backfill.

For the Königsteiner Höfe project, the milled material was transported away for recycling, as the sloping drainage trench was to be lined with a fleece material and filled with special drainage gravel . Collected rainwater will flow down to pump shafts.

Given all the site challenges and project requirements, Höfling Erdbau site manager Daniel Korn says that “the choice of equipment was almost perfect for this task.”