Non-circular HOBAS GRP Pipes Renovate Aged Sewer Networks in Belgium

As part of a campaign to rehabilitate the sewer networks of the Brussels-Capital Region, Hobas supplied 15 kms of non-circular GRP pipes 500/1000 to 1380/2070 mm.


The Brussels-Capital Region comprises 19 municipalities and is home to around 1.2 million inhabitants. The region’s sewer network was built a century ago and is already in a rather poor condition. The more than 2,000 km of brick and concrete sewers, around one hundred main sewers, as well as approximately 50 stormwater drainage lines and pumping stations all show material fatigue and undercapacity. Their highly deteriorated condition leads to cracks and consequent floodings, which had already negatively affected the surrounding roads. In view of the network’s failures, the local authorities formed an intercommunal cooperation to face the challenge and rehabilitate the region’s sewer network within the next 20 years. The corresponding works were awarded to various contractors.


For the first part of this massive project, the contractors decided to use trenchless technology to keep traffic disruptions as well as impacts on citizens, retailers, and connected households to a minimum. Hobas GRP NC Line pipes were used for this purpose, since they proved especially suitable for the rehabilitation of the existing structures and offer an optimum hydraulic performance, both in dry weather and during rainfall. Their perfectly smooth inner surface also minimizes friction and prevents the build-up of deposits.


Based on the technical recommendations of the French Scientific and Technical Centre for Building (CSTB) and the French RERAU (Rehabilitation of urban sewer networks) research program, the pipes’ dimensions, thickness, and capacity to withstand external loads were calculated and checked. Following this detailed preparation, Hobas NC Line pipes were supplied in cross-sections of 500/1000 to 1380/2070 mm and in various pipe lengths in order to rehabilitate the existing sewer network as precisely as possible. The pipes were inserted into the old pipe one after the other. In a final step, the annular space between the existing brick structure and the new GRP sewer line was filled with cement grouting. The completion of this installation topped off a series of successfully implemented projects by Hobas in Belgium, where the company has delivered over 15 km of Hobas GRP pipes within the last three years.