Automatic Repair of Manholes in Pulheim

Faced with the need to rehabilitate all the sewerage manholes within the grounds of Brauweiler Abbey in Pulheim, the Rhineland Regional Authority (LVR) opted for the MRT* automatic repair system developed by HDT of Bottrop (Germany), combined with a high-tech coating system from MC.

*MRT = Manhole Rehabilitation Technology
The work was carried out between July and September 2013 by Heikaus KS Kanalsanierungen GmbH, a Krefeld company with a long-standing tradition in the sewerage rehabilitation field that also offers many years of experience with MRT technology and the speciality ombran mortars involved. The team started by blasting the walls of the manholes down to a “sound” base, ensuring optimum preparation of the substrate for the subsequent repair coating. The blasting pressures applied in this operation need to be in the region of 350 to 500 bar. The MRT system generates these through a vertically traversing water/granulate blasting unit centred within the manhole. This eliminates the need for a human operative to be located in such a confined and dangerous space.
Fast and reliable application

The substrate preparation stage was followed by the coating operation, performed by a spinning unit working its way down the manhole shafts to depths of between 2.0 and 3.5 metres. Its rotating head “slings” the high-tech ombran MHP-SP mortar – specially formulated for spray and spinning application methods – onto the prepared surface. Within the spinning unit, the material is accelerated to such a speed that it compacts on impact with the manhole wall. The DySC® technology of the reprofiling and coating system promotes further consolidation of the mortar matrix during the service lifetime of the coating, extensively preventing the penetration of aggressive substances. Within three minutes, the MRT system had created a new layer of 15mm per square metre with no spray shadows or unevenness, greatly reducing the time conventionally required to rehabilitate a manhole shaft. And because the coating is not only easy and quick to apply but also water-resistant after just three hours, the sewerage system downtime was likewise kept to a minimum. To ensure effective protection of the manholes against biogenic sulphuric acid corrosion, LVR chose the high-tech coating ombran CPS from MC for the Pulheim project. A special accessory in the form of a coating head meant that this hybrid silicate coating could also be applied with the MRT system.