More than 900 M of Large-Diameter Sewer Rehabbed
The community of Zonhoven in the Belgian region of Flanders rehabilitated the town’s combined sewer lines with diameters of DN 1,400 mm and DN 1,300 mm as part of a project to renovate its walkways and supply lines.
The company Kumpen N.V. was commissioned to complete the project, and chose UV-curing glass-fiber reinforced hose liners by RELINEEUROPE for the rehabilitation. The first section of construction was completed in five segments, for a total of 905 m between November 2016 and January 2017. The project shows how good construction site preparation, a competent team and powerful curing technologies can be combined to complete sewer rehabilitation projects quickly and economically even with such large dimensions and difficult conditions.
There’s a lot of activity on Stationsstraat in Zonhoven on this cold November day. The cobblestones on the footpaths have been removed from this narrow residential street in a town of around 21,000 inhabitants near the City of Maastricht. A new cycling path will be built here soon. Supply lines are also being replaced, and the sewer is being rehabilitated at the same time. A construction company is busy installing new street lights. Local residents line up behind the construction machinery on the way to their driveways. A powerful dewatering facility has already been constructed to rehabilitate the sewer. As a final preliminary task, the cleaning truck emptied out the 104-m long sewer section to be rehabilitated.
The main sewer line for the town of Zonhoven leading to a treatment plant around a kilometer away lies below Stationsstraat and Donkweg. As a camera inspection showed, leaking sleeves resulted in serious infiltration issues and caused a large amount of water from outside the system to flow toward the treatment plant. This severely impacted the treatment plant’s cleaning efficiency.
To keep the project economical, and the length of construction as short as possible, the town and the engineering firm it commissioned decided to rehabilitate the sewer using UV light curing glass-fiber reinforced hose liners. The technology would not add any extra impact on quality of life for residents in the area, and it would help prevent the district from becoming chaotic due to the many different projects running in parallel. The entire project was affected by difficult weather conditions, including strong rains and extremely cold temperatures.
The 104-m long Alphaliner1800 was manufactured and delivered to the construction site ready to install in accordance with the structural analyses for the project with a total wall thickness of 8.4 mm. The shipping crate containing the Alphaliner weighed almost 8 tons. The Alphaliner1800 was designed for extremely high structural loads, allowing for economical rehabilitations even with thin walls or for sewers of large dimensions. Production focused specifically on using an ECR fiberglass quality with good transparency for UV light curing, as this optimizes the curing process.
The hose liner is too heavy to move with pure muscle alone. A powerful crane is required to lift it out of the shipping crate and onto the conveyor belt. Installing hose liners in a dimension of DN 1400 is a unique challenge, even for the experienced rehabilitation company Kumpen N.V., which has been working with hose liners for 10 years. For this reason, two application technicians from RELINEEUROPE were on the construction site to support this project.
During the first step, the anti-slip foil was inserted into the sewer section to protect the liner material from damage. Then the team could pull in the hose liner with a powerful winch using the conveyor belt and blow it up with compressed air. The cone was removed first in order to be able to insert the large hose liner into the shaft, which is just 1 m wide.
Enormous pressure is exerted on sealing packers when rehabilitating such large diameter dimensions. For this reason, specialized equipment was used on the construction site in Belgium to increase efficiency and safety. Besides an easy to install system for securely bracing the packer in the channel, it also includes a collapsible folding packer made up of three circular elements — in contrast to other systems with two — and a specialized hoist. This makes it very easy to insert the packer elements into the shaft.
During installation, this packer was used first to attach the top element and then to lift the liner using the hoist. The other elements can then easily be installed afterward and fixed securely with steel pins and tension straps. After the packer was set in place and the liner inflated, the team could then insert the UV light chain through a specialized installation port. The folding packer has a cover attached with screws for this purpose, which can be opened to bring in the light chain. A compressor was used to calibrate the hose liner to the required working pressure. To do so, the liner material was pressed tightly against the walls of the old sewer, creating a new line within the line.
The REE4000, RELINEEUROPE’s most powerful UV curing system, was then used for the curing process. For this project, the rehabilitation company used UV light with a total output of 18,000 watts.
The new REE4000 UV system type facilitates a high degree of automation during the construction process. The system operator could input the curing parameters directly from the delivery slip using the integrated QR code scanner. This allowed all relevant construction site data to be automatically included in the curing log. The ignition points for the UV bulbs and pulling speed could also be set automatically. On this DN 1400 Alphaliner, the 8.4-mm thick laminate was cured at 80 cm per minute and was completed after approximately two hours with an installation length of 105 m.
“We were even able to finish a meter a minute when curing the sections with diameters a little under DN 1,300 mm,” explains RELINEEUROPE application technician Mario Saalow, outlining the benefits of the powerful technology. In the past, the maximum possible speed for these kinds of dimensions was 30 cm per minute.
The estimate used for the curing speed was conservative due to the cool temperatures and cool standing groundwater, in order to guarantee reliable curing for the large diameter liner. This project, then, doesn’t even represent the maximum achievable speed: significant improvements are possible.
Installation and pulling speeds are especially important with large diameters, to reduce the enormous costs for dewatering, for instance, while at the same time minimizing installation risks. Saalow believes that the system operator’s ability to maintain a clear overview of the curing process using the swiveling front and rear cameras integrated into the light chain is another advantage. Ultrasound sensors in the chain recognize the end of the rehabilitated section and switch off the system fully automatically at the end of the curing process.
The Kumpen N.V. Team had rehabilitated a total of 11 sections in this large diameter project for Zonhoven by the end of November. The shortest of these was 20 m long, the longest 169 m. One unique challenge for the team was passing under a train line while dealing with a bend in the sewer.
“The project is going well, and we are very satisfied with the UV system technology” says Kumpen project manager Kristof Maesen. “The curing speed, in particular, is very good.”
Twenty-five employees work in two teams in the Kumpen N.V. Renovation Division, which completes sewer rehabilitation projects in Belgium and The Netherlands. The company employs a total of 450 workers, making it one of the largest civil engineering firms in Belgium.
With an experienced group, good preparation of the site, and equipment adapted for this dimension of hose liners, the rehabilitation firm Kumpen N.V. once again proved its competence in large-diameter rehabilitation.