An industrial area in Leonberg near Stuttgart is changing its appearance. Here, the developer is replacing an outdated manufacturing centre with a modern building. After demolishing the structure that stood above ground level, the company Berb from Bösingen took on the task of removing the basement structure, including the concrete foundations, creating a 6,000m² excavated pit that needed to be secured. Thanks to a Kemroc KRD 120 (120kW) drum cutter with a KRM 60 rotation unit mounted on Berb’s own crawler excavator, the retaining walls constructed from girders with timber lagging, were installed quickly and efficiently.

Combining assets

Bantle Entsorgung und Rückbau in Bösingen, Berb, was founded in 2017 by Georg Bantle. This is a sister company of the road and civil engineering company Gebrüder Bantle from Bösingen on the edge of the Black Forest. With qualified personnel and its own machine and equipment park, Berb has completed important demolition, disposal and earthworks projects throughout southwestern Germany. Kemroc excavator attachments have been part of the joint equipment arsenal of both companies for some time now. A patented chain cutter attachment is used for gypsum mining at a gypsum deposit owned by the Bantle brothers, whilst Berb also use a 6t cutter wheel attachment.

The demolition of the remaining building structure in Leonberg was initially carried out with an excavator plus hammer and shearer attachments. However, to then create and secure the excavation pit for the future building complex, a previously untested approach was taken. A company owned 26t excavator with a drum cutter attachment was used to install the girder and plank shoring system.

Installation of this shoring system (also known locally as ‘Berlin shoring’), requires double-T steel girders to be rammed into the ground at regular intervals and then wooden planks are used to fill the space between the girders. To create space for the shoring, the soil is normally removed using an excavator with bucket. However, if the bucket removes a large boulder, voids are left behind the shoring which then needs to be backfilled. To avoid this, it was decided to try a new method using an excavator with a KRD rotary drum cutter attachment. The range is a relatively new addition to Kemroc’s range of excavator attachments with nine sizes available for excavators from 0.5t to 50t operating weight.

In Leonberg, a KRD 120 was delivered to the construction site.  It was mounted on the excavator together with a Kemroc KRM 60 rotation unit. This range of endlessly rotating rotation units for excavators from 2t to 70t enables accurate positioning of the drum cutter attachment at any angle to the material to be milled from any excavator position. While working in Leonberg from February to May 2022, the drum cutter attachment was used to remove material from between the steel girders from the bottom to the top producing straight, vertical walls, without the operator having to continuously reposition the excavator to move from one section to the next. The result was smooth, flat walls with the correct amount of space for insertion of the timber planks.

“Thanks to this combination of equipment, our operator managed to remove the correct amount of material quickly and accurately from different layers containing rocks or soils with large amounts of stones,” reported Berb site manager Florian Eisele after the completion of this project. “We also produced a very small amount of excavated material, keeping removal and landfill costs within tolerable limits. In any case, in this type of application, success is not determined by the production rate of the Kemroc attachment, but rather about accuracy.” Using the combination of equipment in conjunction with a fully hydraulic quick coupler and a standard bucket had additional benefits as Eisele further explained: “The operator could quickly and easily alternate between milling and loading the excavated material, so the excavator was utilised in the best way possible. This saved us from having an additional 8t excavator in Leonberg.”