Pressure pipe Bornholm Street
A large main pressure pipe runs between the Damsterdiep sewage pumping station and the Garmerwolde sewage treatment plant (STP). This pipe carries 80% of the city's wastewater to the STP treated . The municipal sewer system connects to this main pressure pipe at various locations throughout the city. One of these locations is on Bornholmstraat, near Sontweg. We will be replacing this connection in October 2025.
Reason
In 2019, we discovered that the connection between the municipal pressure pipe and the main pressure pipe was leaking. The connection was then sealed with a repair clamp. This allowed us to quickly stop the leak. With a lifespan of approximately 10 years, this was only a temporary repair. That is why we are now replacing the clamp with a more robust and durable solution.
Execution of the work
To reach the connection, the construction pit must first be excavated. Once the connection is exposed, we can dismantle it. We do this in dry weather. Before dismantling, we pump out the pressure pipe and the buffers in the sewage pumping stations as much as possible. This creates (buffer) time to temporarily take the pipe out of service.
The connection can now be dismantled. We will temporarily close the opening on the main pressure pipe. This will allow the main pressure pipe to discharge wastewater again. At the same time, we will start constructing the new connection from the municipal sewer. To connect to the main pressure pipe, the buffer and the pipe will first pumping stations again. The temporary closure on the main sewer can now be removed and the new connection can be completed. In total, this job will take approximately 4 weeks.
Location
The work will be carried out on the industrial estate near the Danish Port at the intersection of Sontweg and Bornholmstraat. Bicycle traffic will be diverted while the work is being carried out. The adjacent business parks will remain accessible. Coordination with these companies will take place.
Planning
Feb. – April '25: preliminary research and surveying
The connection, which was repaired in 2019, was excavated, examined, and measured in 3D at the beginning of April. With these measurements, we can create a new design and prefabricate the parts.
April–September 1925: design and research
The design is being worked out in detail so that we can order the parts. We are also investigating how best to buffer the wastewater during the execution of the work. This gives us a good insight into the time we have to carry out the work.
Oct. 25: work in progress
We can only carry out the work if there is not too much rainfall. Heavy rainfall means there is more waste water in the sewer pipe, which reduces our buffering capacity. Less buffering capacity gives us less time to carry out the work. The actual replacement of the connection is now scheduled for October, but this is still dependent on the weather forecast for that month.
Nov. – Dec. '25: completion and aftercare
Once the connection has been replaced, we will leave the work site tidy. The hole will be filled in, any damage to the road repaired, and the lawn reseeded.
Execution by contractor consortium GMB Heijmans infra
The work is being prepared and carried out by the GMB Heijmans infra consortium.
Questions, complaints, and reports
Implementation
If you have any questions about the execution of the work or the traffic measures, please contact Johan Poelsma, environmental manager at GMB Heijmans infra, on +31 (0) 528 281100 or at jpoelsma@heijmans.nl.
Project
If you have any questions about the project, please contact Gaby Krikke, environmental manager at water authority , on +31 (0) 50 304 8911 or at g.krikke@noorderzijlvest.nl.