The project was for the municipal client, Lille Métropole Communauté Urbaine (LMCU), who saw the benefits of using Trenchless Technology for its sewer rehabilitation with the Alphaliners from Reline Europe.

Until recently, the GFRP lining system and the UV technology were unknown to LMCU, and while sceptical at the beginning, the record of previous installation results and successfully implemented projects convinced the client.

The job was awarded to sewage system specialist AXEO Brumath, France, and had to be completed within a short time frame of only a few months – between March and July 2011.

In Emmerin, near Lille in northern France, the main intercepting sewer leading to a wastewater treatment plant had become derelict. The sewage system, which had been built in the 1970’s was showing major signs of damage.

Although there was nothing wrong with the statics of the old pipes; excessive corrosion, displaced pipe couplings and penetrating roots were causing leaks, and up to 90 per cent of the pipe system was overgrown. The rehabilitation was essential.

With an overall pipeline length of 4 km and pipe diameters of up to DN 1,200 mm, the rehabilitation project was a demanding project that had to be completed within a very tight time frame. The sewage system runs along a nature reserve which will likely be restructured in mid 2011.

Construction Supervisor at AXEO Brumath Michel Moller said, “This is the largest project of this kind in France to date. Considering the length, diameters and short completion time, the entire French rehabilitation industry is considering this task as a reference project.”

The narrow time frame as a challenge

The challenge for the professionals at AXEO Brumath was to complete the project, including all preparation and finishing work within the narrow time frame. The pipes affected were two main intercepting sewers. The first, with a length of 1,255 m and a diameter of DN 1,000 mm, runs from the pumping station at the nearby industrial area and the Port Santes along the nature reserve ‘Le Parc de la Deûle’ to the wastewater treatment plant.

The second intercepting sewer – diameter DN 1,200 and 3,009 m in length – connects the commune Wattignies with the wastewater treatment plant. A 243 m feed pipe with a diameter of DN 600 mm leading to this main intercepting sewer had already been rehabilitated.

The initial phase involved restoring the segment from the pumping station to the wastewater treatment plant. This required the installation of a 1.4 km long water by-pass system through which the water could flow from the industrial area to the plant during the construction phase.

Mr Moller said, “Designing the water drainage bypass as a single, large system makes sense. It enables us to perform work along the entire construction site efficiently without any major loss of time caused by things like daily sewer cleaning.

“In this first segment, DN 1,000 mm Alphaliners, with a wall thickness of 7.2 mm, were installed over a length of 1,255 m. The logistics on their own in this respect were immense. The total weight of all installed liners amounts to approximately 236.5 tonnes. Reline Europe supplied the liners in the lengths required for the respective installation segments. The Alphaliners were then pulled into the sewer directly from the lorry with the help of a conveyor.”

Also on site was David Veltz from Reline Europe who had already co-operated closely with AXEO Brumath during the preparation phase. “Obviously, entering the French market with such a large project is a challenge for us. But we all acted in concert, from the production employees to the management. That the project was a success is due to the good co-operation between the city of Lille, AXEO Brumath and Reline Europe,” Mr Moller said.

Fast curing – short installation time

Once completed, work on the approximately 3 km long intercepting sewer was carried out. Again, the construction vehicles were only able to drive to the drainage system on specially built construction roads.

Thanks to the clever choice of the installation segments and the deployment of two construction crews at the same time, the construction team was able to complete the construction work even faster than originally planned. Up to five liners were installed per week.

The company opted for various logistical solutions to implement the liner order. The Alphaliners DN 1,000 mm, for example, were delivered in individual boxes. The larger DN 1,200 mm Alphaliners, however, were delivered in overseas containers.

“With this method, we are much more flexible and also more environmentally friendly, since we do not use disposable packaging. We are thus also able to deliver very heavy liners reliably to the construction site,” said Mr Veltz.

On site, the large-dimensioned liners were pulled into the sewer system with a cable winch. By using a 1.5 km long winch cable, the set-up time between the individual installation segments could be kept to a minimum. Once the liners were inflated, UV light was used for the curing process at a speed of approximately

40 cm per minute. To achieve this, a light train of nine UV lamps, with a capacity of 1,000 watts each, was moved along the installed liner.

Even with longer installation sections, the curing process only took a few hours. Due to the well-structured work and fast processing method, up to 150 m of sewer pipes could be rehabilitated on an average work day. Meeting the tight time frame of the trenchless sewer project was therefore not a problem.

Conclusion

As well as saving time and protecting the environment, trenchless sewer rehabilitation with UV light curing GRP liners has another advantage.

“After 30 years of experience in sewer rehabilitation using hot water as the curing medium, I am now able to compare the two methods. In addition to the advantages for the environment, the UV system also has benefits for the residents. While hot water curing requires the construction site to be manned day and night, this method allows interruptions and can be continued the following day,” said Mr Moller

In his opinion, the system used in Lille is currently the best sewer rehabilitation system available.