3D modelling solved the sewage problems
How do you fix 40 years of sewage problems and a poorly documented spaghetti of pipes, manholes and cables in the ground? COWI found a solution, which the Stavanger WS authorities, the cable owners, the trenching contractors, as well as the residents along the troubled road are very pleased with.
The Boganes road is located at Hinna just south of the Stavanger city centre. The surrounding area has for years been troubled by a poor sewage system which at times led to sewer pollution in the sea. In particular it affected the residents and boat owners at Jåttåvågen, a new residential side in Stavanger.
After repeated protests from the residents the municipality of Stavanger finally engaged COWI in 2015 to find a definitive solution to the problems.
“Due to fairly inadequate documentation of the existing infrastructure, we had to take some unconventional measures to solve the challenge”, says Håkon Roger Galde at COWI Stavanger. He has been the engineering project manager and the technical construction manager for the WS project. “We soon realized that it was going to be a complex job. It turned out that there was very much and quite unmanageable infrastructure in the ground”.
“To get as good overview and control of the task as possible we were fortunately allowed to perform two significant measures before we started the design process”, he continues. “The first one was to do a few extra test excavations at critical locations to find out what really lied in the ground, and simultaneously also measure the exact position of the infrastructure, not only the x and y values, but also the depth information, the z values. The second assessment was in fact to model all this existing infrastructure in 3D based on the recorded findings and the documentation we had, and to use this as a model basis for the new design.”
“It actually turned out that the map and reality often did not match. For example a pipe, which on the map was plotted as a line, was in reality ten 110mm pipes. You can re-align one or two pipes, but it is incredibly difficult to do ten. Along with an excessive amount of pipes and cables were also many purpose-built manholes, everything with small sloping. At the most critical point, four fairly large WS pipes crossed each other with different degrees of slope”, illustrates Galde.
“It was therefore very rewarding to have a close dialogue with the various infrastructure agencies to get the 3D model of the existing situation as accurately as possible. We actually ran an extra round with all the agencies, where we sat together around the model and made certain we had the correct data of the right cables and pipes etc. Consequently we had the opportunity to create a best possible WS plan for this complex project.”
The 2100th century’s most important project
“The result was that we never have experienced such a good control of what really lie in the ground”, empathizes Håkon Roger Galde. “In fact we did not get one single change notification from the contractor. I've never experienced that before.”
Stavanger municipality has described the WS project as 2100th century´s most important project, because even the finished construction was a success. Galde was also hired by the municipality to do the technical construction management of the project. Everything professional was therefore a close interaction between consultant, contractor and developer.
Win-win for everyone
“Short communication lines gave me a very good opportunity to follow up on theory and practice”, tells Galde. “Deviation status in relation to the model was on the agenda in every construction meeting. You can of course never get absolutely everything documented perfectly, but the feedback from the contractor was that this was close to optimal. The contractor could plan their work on a completely different level.”
“The engineering and construction method is a win-win situation for all parties. Everyone get substantially more value.”
Substantial added value
“We as WS engineers get a much better design starting point, so that also our plans are improved, which in turn will benefit our client”, he adds. “Stavanger Municipality not only receives better WS documentation, they can also coordinate their work easier and better. The overall result is minimal change orders, better quality and reduced costs.”
“The cable agencies on their side get their infrastructure considerably better documented and quality assured in terms of positioning. They can hence plan new projects in good time, and also benefit from a better basis for joint piping and participation in constructions.”
“Even for the trenching contractors it involves better and more informative plans”, says Galde. “Well documented plans can prevent damage to cables and pipes on the construction site. Model data can be used for machine control and survey data. The 3D model can also provide simpler and better collaboration with the contractor's own suppliers, which in turn provide the ability to schedule trench work and project progress better.”
“In the long term I think the approach we've used will become the future way of working”, says Galde. “The project has already opened the eyes of many local infrastructure operators. 3D modelling and the close collaboration in both the planning and execution phase have resulted in more industry players now having acquired Novapoint WS and turned to COWI for assistance in using the tools for their needs.”
“The WS product library in Novapoint WS is invaluable in the engineering design work. Most WS products are now available as model objects in the library and can be used directly in the design. Elements not found in the libraries we model ourselves and get them built according to the models. The cement foundry we use is for example building our purpose-designed sewer manholes directly from my digital models. When you model a manhole model in one to one, you know exactly what will be missing. The quality assurance can be made in the modelling phase and minimizes errors and deficiencies on the construction site.”
“With the BIM technology in Novapoint 20 the modelling is taken to a whole new level, especially in large development projects. I am currently responsible of WS design for the new hospital in Stavanger. There we share model files with both architects, landscape architects, energy and structural engineers, and others.”
“We are also working on a new city district project for Stavanger where we, together with Telenor, Lyse and Get, is 3D-modelling all existing infrastructure both below and above ground, in order to achieve better and detailed zoning and design of the area in the future.”
“Modelling of reality is without a doubt the future way of doing it”, concludes Håkon Roger Galde at COWI.