City of Erfurt uses sealing plug system from Schwalm
Seals effectively

Between the 50s and 70s, local authorities integrated additional branch pipes and adapters into their sewer systems when planning and developing residential areas so that they were already equipped for future developments. But often these were never subsequently needed. As a result, there are still open cross and blind connections which do not conform to legal regulations, creating a major need to seal these retrospectively. This is the case in the city of Erfurt, which is using Schwalm’s own ultility patent-protected sealing plug system.

“We are absolutely convinced of the sealing plug system from Schwalm,” emphasises Jörg Behrendt, head of Sewer Network I Operations for the city of Erfurt. “Because the idea that innovator Willi Schwalm developed almost a decade ago in conversation at the IFAT 2004 is simply brilliant and still has a pioneering character even today. Back then, the Sewer Network Operations of the city of Erfurt confidently monitored the test carried out with the sealing plug pilot trials by Schwalm. Other technical procedures, which were available at this point, did not appear to be suitable as a long-term solution.

Even the results from the pilot phase were impressive because open connections could be quickly, effectively and completely securely sealed off. Controlled remotely by the operator, the sealing plugs were transported to the connection pipe using the Schwalm repair robots Talpa FSR 1330 and Talpa FSR 2060 and then inserted and tightened in place. If necessary, the plug can be removed at a later date so the connection can be used and retrieved from the location. The working arm of the robot is equipped with an air-hydraulic impact wrench to carry out the assembly or disassembly. In accessible sewers, the plugs can be fitted manually.”

Inventory and status evaluation

As in many other cities, there are still a multitude of open cross and blind connections in the Erfurt sewer system dating back to the past. The recent sewer system status evaluation showed that there are still several hundred open or improperly sealed connections left to repair. These are shown by the red dots on the plan (excerpt) of the Erfurt sewer network.

Due to the positive experiences, the Sewer Network Operations for the city of Erfurt work with Schwalm Kanalsanierung from Bad Hersfeld. After extensive preparations and planning the traffic schedule with the necessary barricades in Erfurt city centre with 72 hours’ notice, work began in August 2013 – the first 4-week deployment of Schwalm employees Andreas Breul and Ronny Weißbrich began in the state capital of Thuringia. During this period, over 170 open blind connections were professionally sealed underground. In October 2013, work continued with the positioning of a multitude of sealing plugs over a four week period. “Work will continue at the start of 2014,” explain Schwalm project supervisors, Michael Draband and Jörg Behrendt.

“The repair progress including traffic restrictions in Erfurt has worked really well up to now. The Schwalm sealing plug system is working brilliantly. For this reason, we are entering the coming year with confidence and will continue to repair the cross and blind connections during the next stage, which will be followed by further phases in the coming months and years.”


Technology always develops from the primitive to the complicated and then to the simple. (Antoine de Saint-Exupéry, French aviator and author [1900 – 1944])

The specialists from Schwalm Kanalsanierung and the City of Erfurt have worked together and invested much effort and energy in developing the Schwalm sealing plug system. And it has more than paid off. The system has been perfected. It is easy to use and all the legal conditions are fulfilled. “A very important task has been safely and professionally completed underneath Erfurt,” say Michael Draband and Jörg Behrendt unanimously.