Tuesday, May 21, 2024


Per Aarsleff Pipe Technologies comes from a history of developing, producing, and installing needle felt liners since 1979. However, in the recent decades it has concluded that if it wants to maintain a leading position in the relining market, it needs to master all products. Therefore, the company started to produce glass fibre liners about 10 years ago, but also to test close-fit systems and precast glass fibre reinforced pipes. PAPT has a strong feeling that having experience with different kinds of systems, both on the production and the
installation side, will benefit clients as well as its business since it can optimise the project execution.

On a clear and cold winter morning in February 2022 the renewal of 3,000 m of DN800 began in Fredrikstad, Norway. The client had some concerns about the project since the pipe was located under farmland and under the Gamle Fredrikstad Golf Club. How could Olimb, a part of the Aarsleff group, ensure that the least possible harm was done to the ground while the rehabilitation of the 3,000 m was executed? With many years of experience from different systems Olimb chose a solution with the glass fibre. The size of the pipe, the access to the manholes and the length of the bypass pumping all pointed in
the direction of a glass fibre liner. The bypass pumping was a key to success in this project.

After some weeks with perfect weather conditions for installing liners, the weather changed into a more mild and wet period. Therefore, the people on the ground struggled with both installations, and massive water volumes. However, after three months, lots of water and ensuring the golf players game during installations, 3,000 m of glass fibre liner was installed with success and with the client’s satisfaction and approval.

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Interesting Facts from the Fredrikstad project include:
• 2,941 m of renewed pipe
• 22 installations
• 3 months duration
• Difficult ground conditions
• Challenging bypass pumping


Not only technical solutions but also cooperation is important when having a partner. In Esbjerg in the Southern part of Denmark a 6 km long pipe underneath a breath taking and vulnerable nature area had to be renewed.

The client had the option to replace the existing pipe and manholes with a new system. But it would affect the area for many years and with that in mind the client asked for a CIPP solution. This was both more sustainable and less time consuming. However, it was still a concern that big vehicles had to enter the area to perform the installations. Aarsleff was chosen for the job and immediately set a team with two other well-known contractors to solve this complicated project.

As it was in Fredrikstad in Norway, the bypass pumping was also an important part of the project. The bypass pumping set-up was designed to deal with up to 1,075 l/s with several pumps being used to ensure the function of the existing pipe. Needle felt liner cured with steam was chosen for smaller diameters or shorter installation for mid-range diameter. Needle felt liner cured with water was chosen for large diameter and long lengths and UV cured glass fibre liners were chosen for manholes and mid-range diameter pipes. For the very small diameters LED curing technology was used, and the laterals were rehabilitated with Aarsleff long top hat profiles.

The project was started in April 2021 and handed over in December 2021. Beside the technical solutions the coordination between all the parties were essential to be successful. The relevant authorities, biologist, client, consultants, partners, and users of the area were involved in the project. All with a positive mind before, during and after the project.

Salient facts about this project include:
• 600 m of renewed pipe between DN150 and DN1000
• 44 installations
• 6 months execution time
• Difficult ground conditions
• Challenging bypass pumping
• Combining different CIPP solutions to be as efficient as possible
• Coordination and professional Project management


In the summer 2022 the city of Malmö had to renew some of its big collectors. The pipes were either DN1400 or DN1500 and had transported wastewater from the residents of Malmö for almost 100 years. The client was VA SYD and they had cleaned and evaluated the pipe. It had several cracks in the crown and therefore it was decided to rehabilitate the pipe.

Because of the traffic, fire station and schools the client wanted as few excavations and installations as long as possible a CIPP solution was chosen. The Swedish part of Aarsleff analysed the job site on-site and had three solutions in mind. A GRP system where precast glass reinforced pipes could be pushed into the existing pipe, a UV cured glass fibre liner, or a heat cured flexible liner. Due to the requirement of client in terms of excavation and long lengths a solution with a flexible needle felt liner was chosen. The existing pipe also had a lot of bends and here the flexibility of the needle felt liner was preferred. The entire length of the existing pipe could be renewed with only six installations in total. Only a few excavations were necessary. Both the GRP and UV cured liner solution required extra excavations.

The client was satisfied with the project and in terms of sustainability. A CIPP solution saved up to 650 t of CO2 compared to excavating and installing new pipes. Also, the saved execution time was very valuable for the client.

Interesting Facts pertaining to the Malmö project include:
• 1,200 m of renewed pipe of DN1400 or DN1500
• 6 installations
• 1 month execution time
• 1000 l/s by-pass pumping
• High density traffic area, schools, fire station etc. in the installations area.
• Choosing one method to optimised installation lengths.
• Saving CO2 compared to excavation projects.

The processes in the three projects highlighted in this article are typical of how Per Aarsleff Pipe Technologies analyses and chooses methods in CIPP projects. Because the company has many years of experience with most of the products and methods in the market, it can also choose the most optimal solution for the client. For the project in Norway, UV cured liner was the best solution due to the size and location of the existing pipes. For the project in Denmark, PAPT had to use almost all its methods due to the variety in pipe sizes and in Sweden curing long lengths with water was the best solution to avoid extra excavations.

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