How a city upgraded its sewer systems with vitrified clay pipes
The remit of works involved re-routing an existing sewer directly under one of the city’s busiest roads. Temporarily closing this arterial route for an open trench excavation wasn’t an option as it would have caused severe disruption to traffic across the area.
The challenge
Specifiers at the City of Ludwigshafen worked with the contractor, Friedrich Eisen GmbH, to find a solution that would allow the traffic to continue uninterrupted at street level while the work took place below ground.
The renovation work, which took 10 weeks to complete, was carried out in Friesenheim, one of the city’s most densely built-up districts. The work required the new sewer section to be installed on a side street connected to the main road.
Joining these to the main collector would normally have required digging an open cut trench and closing the street entirely for pedestrians and vehicles. This would have resulted in major disruption for commuters, residents and businesses in the district.
As a result, the city issued a public tender that ruled out road closures.
The solution
The Mannheim-based civil engineering company specialising in sewer rehabilitation, Friedrich Eisen GmbH, was awarded the contract following a tendering process.
The team proposed the construction of an underground arch-shaped heading using traditional mining methdos, digging manually toward the reception shaft. Inside the tight 1.5-metre bore, a ceiling-mounted rail system was installed to move the sewer pipes into place while an excavator threaded the pipes into the access pit. Above ground, working conditions were also tight due to the narrow width of the side road.
The team laid 155 metres of Steinzeug-Keramo KERA vitrified clay pipes with a 400 mm diameter and 112 metres with a 300 mm diameter. Another 280 metres of vitrified clay pipes with a diameter of 150 mm were also used for connecting secondary routes.
With a standard pipe length of 2.5 metres and integral joint connections, they could be laid quickly and accurately without any complications. Once in place, the pipes were set in concrete and the tunnel was filled with a suitable backfill material to complete the installation. At the same time, the sewer line on the side street was completed on schedule.
Choosing the right material for this project was important to the city of Ludwigshafen am Rhein so that they could align with sustainability goals and ensure long-term value for residents and businesses.
Steinzeug-Keramo’s vitrified clay pipes were selected for their sustainability benefits, quality of manufacturing and efficient installation. Made entirely from natural materials such as clay, chamotte and water, they are fired at high temperatures, giving them exceptional durability and resistance to corrosive chemicals and gases found in sewers.
The results
Vitrified clay pipes were particularly suited for this project because of their inherent strength and high load-bearing capacity, which allows them to withstand both static and dynamic loads, performing well under routes with heavy traffic.
The longitudinal compression resistance of Steinzeug-Keramo vitrified clay pipes can be as high as 100N/mm2, which made them a compelling choice on this project.
Their smooth interior surface also minimises friction and reduces the likelihood of blockages. This characteristic is especially beneficial in preventing the accumulation of debris, which can again lead to costly repairs and service interruptions.
As vitrified clay pipes are made entirely from natural materials and contain no harmful substances, they can be left in the ground without risk of leaching and polluting the surroundings. This makes them not only durable material for this project but also environmentally safe.
Independent research conducted by Project Hub 360 confirms that if the operational lifespan of a sewer system exceeds 40 years, vitrified clay pipes represent the most economically viable investment. Although clay pipes require a slightly higher initial investment of only around 4%, they offer cost savings of up to 65% in the long run compared to alternative materials.
Background details
Building owner: Stadt Ludwigshafen
Contractor: (company carrying out the work) Friedrich Eisen GmbH, Mannheim
building materials retailer: Union Bauzentrum Hornbach, Neuhofen
