Major sewer system repair in Tilburg-North

Sometimes reality is completely different from what first meets the eye. This was demonstrated once again last January, when Rions Riooltechniek discovered a small-scale soil subsidence near a sewer well on the IJpelareweg in Tilburg-Noord. A thorough analysis showed that the problem was much bigger than the sinkhole alone. Four sewage pipes that carry wastewater from almost the whole of Tilburg to the water purification plant had subsided and burst, most probably as a result of heavy rainfall and the high groundwater level. A calamity that called for a quick and professional solution. On the way to it, Heijmans and Vanderkamp - The Dutch Water Engineers from Zwolle joined forces.

After the observation by Rions was a fact, the company, at the intercession of the Municipality of Tilburg, immediately sought contact with a number of external parties. One of these was Heijmans, which was asked to both advise and devise a physical solution to the calamity. "Together with the Municipality of Tilburg, Rions and various advisors, we first carefully analyzed the situation," says Wouter van Leeuwen, project manager on behalf of Heijmans. "In doing so, we quickly discovered that several wells on site were subsiding as well as defective, causing both groundwater and sand to flow into the sewer. But it didn't stop there. As a result of the subsidence, a sewer pipe with a diameter of about 2 meters was also damaged. And that in turn led to more sinkholes. What at first appeared to be a relatively small-scale soil subsidence turned out to be a much larger problem with ditto proportions. Rapid intervention was therefore a must." 

Challenges 

Heijmans moved swiftly to find a suitable solution. The task was clear, as were the enormous challenges it faced. "The sewage pipe, which normally drains about 15,000 cubic meters of sewage water per hour together with three other similar pipes on site, lies at a depth of 6 meters in the groundwater," Wouter explains the biggest challenge. "Replacing it is a mega job, also because of the fact that a gas line has to be moved. In March 2024, we presented a design to replace the sagging wells and the sewer pipe. In the meantime, however, the groundwater level remained very high and further subsidence occurred."   

Eventually, the three other sewer pipes at the problem location were also found to be damaged and subsiding. All this forced Heijmans to take swift action. In September this ultimately resulted in a cofferdam measuring 17 by 42 meters. A very large-capacity pump was needed to move the water from in front of the problem location to behind it. An installation that can only be supplied by a few parties in the Netherlands. Heijmans eventually ended up with Vanderkamp, a leading supplier of temporary pumping solutions. "Subsequently, together with the Water Board and the Municipality of Tilburg, we looked at, among other things, what capacities were required and what flow rates we had to take into account," Wouter continues. "All that was translated by Vanderkamp into a design of a huge installation consisting of five pump sets that was installed prior to the closure of the sewer pipes in June. This pumping plant, with a capacity of as much as 14,500 cubic meters per hour, will remain in place until we complete the work. Starting with the sewer replacement from January 2025. The project is expected to be completed in May 2025."

Construction

Until then, the pump installation supplied by Vanderkamp is running 24/7. Sales engineer Marco Wesseling and project leader Michiel Sieders are closely involved in the work in Tilburg on behalf of the Zwolle-based company. "After Heijmans indicated to us that a pump installation with a very large
 capacity was needed, we first consulted with the Municipality of Tilburg, Heijmans and the Water Board to see what the best location for the installation would be," Marco says. "Then, again in close cooperation, we made various designs and went on site to see how the entire route of pump sets should run. These findings were incorporated into a 3D design. We also made various calculations regarding the electrical and hydraulic provisions. After the pumping plan was also ready as the final piece, we started the construction of the pumping plant."

Capacity

The challenges in doing so had multiple dimensions and angles, according to Michiel, who, in addition to day-to-day project management on behalf of Vanderkamp, was also responsible for translating the pump design into practice. "First, there is the capacity that the installation must be able to deliver. Within the sewerage profession, there are the terms dry weather supply and rain weather supply, abbreviated as DWA and RWA respectively. Dry weather supply refers to the sewer flow resulting from shower and toilet use, among other things. In wet weather, rainwater is added to that. This can cause large differences in sewage flow. However, our system is perfectly designed to deal with this. However, the approximately 14,500 cubic meters of water that must be pumped every hour is not the maximum capacity of the system we developed. It is much higher. The reason that here the maximum is stuck at 14,500 cubic meters has to do with the fact that the sewage treatment plant behind the pumping station cannot process more." 

A second challenge, according to Michiel, lies in the fact that the wastewater that must be pumped over the problem site comes from the four damaged sewer pipes as well as a separate branch on site. "As a result, you cannot suffice with an installation with combined pumps, but a separate, dedicated pump set is needed for each of the five pipes. Including a backup for unforeseen cases."

Custom 

Vanderkamp has once again signed for first-rate workmanship in Tilburg-Noord. The installation, mainly constructed from standard components, fits seamlessly with the client's specific demands and needs. Marco: "Because we accurately mapped out the supply of water per sewer pipe, we were able to determine the optimum pumping and reserve capacity especially for this purpose. That is the basis. With appropriate pump sets, fittings, valves and flow meters, among other things, we then designed the installation. Then we made some minor technical adjustments on site. That all resulted in a perfect piece of customization and a resounding end result." Michiel concurs. "Large pump volumes and Vanderkamp fit together, as was proven again during this project. We provide the capacity, but also the expertise and the required customization. Here again we were able to put those qualities into practice in a beautiful way and within a great cooperation with Heijmans."     

Cluster of disciplines
Together, Heijmans and Vanderkamp are pulling out all the stops to tackle the problems in Tilburg-North quickly and professionally. In any case, Jan Heijmans, business manager within Heijmans Infra region South, views the progress of the project with great satisfaction. "Teamwork, manufacturability and making connections are not only core concepts within our multidisciplinary construction company. They also come together in a beautiful way within this special project, where all those involved from different disciplines and techniques are enabled to show their specific qualities. All this takes place within a collaboration that is exceptionally successful mainly thanks to the ultra-short lines, clear communication and dedication of the project partners. I therefore have every confidence that we will successfully complete this extensive job within the set schedule."