What about... RWZI Utrecht

The smell of success

You can’t smell zeros and ones. Although... thanks to digitization Utrecht’s sewage treatment plant smells of success. Here’s a short introduction to the Building Information Model (BIM) and virtual reality. 

December 22, 2017

Grey skies, unflappable gulls. Around fifty of them floating around in the so-called secondary sedimentation tank of Utrecht’s sewage treatment plant. They show no interest in passing construction vehicles, which they’ve been exposed to for six months now. De Stichtse Rijnlanden water board has tasked construction consortium Heijmans/GMB with creating a new sewage treatment plant alongside the old one. The project will be complete at the start of 2019.


Bert Post behind his computer with the BIM-model of the RWZI.

‘The major benefit of BIM is transparency and saving time’, says Jurgen Pennings, the consortium’s Design Coordinator. ‘Especially here, as you’re extremely dependent on suppliers in the case of a sewage treatment plant. They are supplying such things as the pumps, electrical equipment, software, pipes and façades. These manifold disciplines give rise to complex design processes and accompanying drawings. BIM enables us to spot conflicts between the different elements sooner. Thus preventing stagnation and costs of failure.’

He retrieves a drawing from BIM and taps on his screen: ‘This is the process water building. Nine parties are involved in the design and implementation. BIM also reduces the chances of communication becoming confused.’ In order to ensure that misunderstandings aren’t possible, every drawing is given a QR code. Anyone scanning the code will immediately see whether or not the drawing has been released for implementation.’


Sat opposite him is Bert Post. The Technical Manager Utilization is beaming. He proudly shows off three-dimensional cross sections of the sand filter building in the making. BIM cuts through the drawing in iterative steps, which can be adjusted to the millimetre. ‘The sand filter building has three layers and plenty of piping. Yet you can view each and every space three-dimensionally from any perspective you want. That way you can quickly pinpoint any issues.’

Extremely handy, even if Post and Pennings were taken aback by the first ‘clash test’: BIM coolly reported 1,080 clashes in the foundations of the sewage treatment plant. ‘False alarm’, grins Jurgen. ‘The system was detecting all the piles ending up in the concrete floors.’


Bert Post and Jurgen Pennings on the site.

BIM’s primary role is to improve the design process. Nonetheless, it also offers collective happiness, expediting the validation of drawings. Post cites a practical example: ‘The definitive design for the sludge processing building had been accepted. Shortly thereafter it emerged that additional facilities would be required. A new 3D model incorporating amendments was enough to convince the client and get validation swiftly.’

Nevertheless, paperwork is not a thing of the past. The implementation of the sewage treatment plant on the construction site is being done in line with some seven hundred fifty drawings. ‘BIM isn’t commonplace out there’, acknowledges Pennings. ‘The 3D model also calls for its own way of working and thinking. A concrete shutterer prefers hard copy drawings, dispensing with the fuss of using a tablet whilst braving the elements.’


Nevertheless, BIM wins in the sphere of implementation as well. Construction supervisors and foremen regularly use prints to illustrate phasing. Moreover, 4D BIM (linking BIM to planning) is on the rise.

Virtual reality

When it comes to the sewage treatment plant under construction, they do have one trump card to play: the Oculus virtual reality goggles. A sturdy frame containing a mobile phone. Anyone putting this bad boy on his head will be stepping into a virtual world. The construction consortium has created three-dimensional films that reflect the reality of around twenty places on the grounds of the sewage treatment plant.

Your editor can try it too. Staggering: he thinks he’s on a sludge tower. In the distance is the dual carriageway Brailledreef, behind him the village of De Vecht. If he looks down, there’s a ten-metre drop. He reaches for a railing, slightly shakily. His hand fumbles around in the air in vain: the steel railing isn’t there.


‘Special software enables us to render any 3D image from BIM true to life within minutes or hours, depending on the thickness’, explains Jurgen. ‘Thus putting you actually in, next to or on an object.’ Virtual reality also helped to get the definitive design for the sewage treatment plant accepted, the two acknowledge. ‘Sometimes 3D images on a computer screen aren’t persuasive enough. For example, the client had some doubts about the dimensions of the pump cellar. Would it not be too cramped, with all the risks that this would entail? Virtual reality provided the breakthrough. They saw that everything would be fine.’

Panoramic view

Are there any conditions attached to use of BIM? Yes, the gentlemen say in chorus: everyone has to unwaveringly adhere to the basic agreements. Stick to the plan, is the motto. Which applies after completion too. The construction consortium will be taking care of the management, maintenance and utilization of the sewage treatment plant until 2029. Jurgen: ‘This has been amply factored into the BIM design already, particularly when it comes to the choices in terms of equipment and materials. We’ve designed things from the perspective of the user, with everything fine-tuned to users.’

A tour of the construction site, where dozens of people work each day. Near the six ® tanks under construction, which are collectively capable of processing in excess of thirteen thousand cubic metres of sewage an hour, is the watch scaffold. Up the stairs to enjoy the panoramic view. Not virtual reality, but a real sewage treatment plant under construction in the autumn sunshine.