First Large-Scale and Technically Demanding HOBAS GRP Jacking Project in the World

A sewer was to be installed under a very busy part of the port in the north of Germany. The specifications were challenging: a fire service exit, port railway and federal railway lines were not to be disrupted under any circumstances and settling had to be prevented over the entire length of the pipeline. Given the fact that trenchless construction saves space and is highly accurate, jacking was truly predestined for this application. The HOBAS Products‘ corrosion resistance also to aggressive wastewater, their smooth outer surface and easy handling persuaded the clients and they ordered jacking pipes with an outside diameter of 752 mm and wall thickness of 50 mm. The pipes were installed six meters under the groundwater table in two drives over a length of 165 meters without any intermediate jacking stations. Although their outer surface is very smooth, the HOBAS Pipes were lubricated with bentonite every 30 meters to reduce friction and speed up the jacking work. It is hardly surprising therefore that the greatest jacking force used was only 1700 kN, which is far less than the limit for the pipes.