Sewer line brought back to service with non-circular Hobas GRP Profiles
When in 2015, an old non-circular concrete sewer had to be rehabilitated in Groningen in the northern part of the Netherlands, Hobas was brought into play. Within only three weeks and under challenging circumstances, the sewer line was successfully renovated with egg-shaped GRP profiles.
Petrus Campersingel is a highly frequented road in the Dutch city of Groningen. It is used not only by cars but also by heavy traffic. This subjects the pipes and structures underneath to particularly high loads – among others an old egg-shaped concrete sewer with a cross-section of 1200/1800 mm, which was found in need of renovation in 2015.
At first, the contractor considered rehabilitating the 277 m long sewer with a CIPP liner, but the corresponding safety factor revealed by the static calculation was too low. So GRP became the material of choice, and the contractor’s reasons for using egg-shaped Hobas NC Profiles 1000/1500 mm were manifold: the fully customizable shape and diameter, the resulting possibility to reduce the diameter of the existing egg profile, the necessary strength to withstand the groundwater pressure and traffic loads, and not least the products’ long lifetime.
The construction works involved quite a few challenges – the road traffic had to be maintained between 6 a.m. and 9 p.m., bicycle traffic was even to be maintained around the clock the soil next to the road was quite weak, and the existing shafts were basically inaccessible. However, a good cooperation between all parties involved made it possible to tackle all challenges successfully. The installation of the Hobas NC Line Profiles was realized from two access pits, one of them in the middle of the pipe route. After the installation of the first part of the pipeline, a GRP shaft with a temporary valve was installed at this access point. The remaining NC profiles were then installed from the second access pit and the pipeline finished by connecting it to an existing concrete shaft.
During the installation, a visit to the project site was arranged by the city of Groningen together with Hobas and the contractor BAM. Forty interested clients used the opportunity to experience at first hand how Hobas NC Line Profiles are installed by relining. The day was a great success and left the visitors positively impressed. Beginning of December 2015, the installation of the 277 m long pipeline was successfully finished after three weeks only. The city of Groningen is very satisfied with the professional implementation of the project and the high quality of the new Hobas NC Pipeline.