Brandenburger overcomes obstacles on relining project
Brandenburger and AKWA have celebrated the completion of a technically and logistically challenging relining project in Poland’s second largest city. The €400,000 (US$420,000) project featured obstacles such as confined space, harsh weather conditions and equipment failure, which made eventual success all the better.
Installing a 280 m glass fibre reinforced plastic (GFRP) pipe with a 1,500 mm diameter and only 10 mm thickness is quite a feat. And to pull it off under a river with the sewer separated from the river’s water by only 1 m of earth – that is something else entirely. That is exactly what Brandenburger accomplished in Krakow, Poland, in August 2016.
Numerous pedestrians, cyclists and joggers make use of the banks alongside Poland’s longest river, the Vistula. Some of them may know that the Vistula is normally 5-6 m deep, 9 m if there is flooding. But most of them would not know that four sewers, now sixty years old, pass under the river. Installed in 1954, the sewers have been in constant use, transporting sewage from one side of the city to the other.
It was one of these four sewer that Brandenburger and AKWA Sanierungstechnik GmbH was tasked with rehabilitating. The challenge was to install a 26 t liner across the entire width of the river; in other words over a length of 280 m with a diameter of 1.5 m. Brandenburger Liner GmbH & Co. KG rose to this great challenge and produced a liner for the project on a new, larger production line.
Throughout project works the Brandenburger team was managed by Marc Albrecht and the AKWA Sanierungstechnik GmbH team was managed by Piotr Grawżym. Together, the project workers dug down 8 m into the sewer in Krakow.
An ambitious project of this kind in Poland’s second largest city requires meticulous planning. This is especially true as certain toxic gases tend to collect in the walls of the 60-year-old sewer and need to be carefully managed during project works. In this case, after pumping out the sewer water and cleaning, the dirt was indeed gone, but it was discovered that the gases were still trapped in the concrete. According to Grzegorz Owczarek, managing director of AKWA, the sewer was vented for two months to let the gases escape. Before that, workers could only go into the sewer if they were wearing breathing apparatuses.
After the gases were vented, the sewer and its two access shafts on each side of the Vistula needed to be prepared for the delivery of the liner. Employees of AKWA had previously dug out wide windows and a construction pit at the entrance, from where the liner could be drawn in later.
To ensure that works were not at risk of sinking into the mud in front of the shaft, teams from Brandenburger and AKWA heaped up minerals at the entrance on the first day of construction. The next step was to smooth out sharp edges in the shafts with a power grinder, position the cable winches as well as the conveyor belt, and finally draw in the foil over which the liner was to slide into the sewer.
A difficult delivery
Delivering the liner to the construction site was not an easy task; the only access to the river was a narrow street too small for the delivery lorry to navigate. The vehicle had to turn around before the entrance and reverse several hundred metres to the construction site entrance. Manoeuvring had to be done precisely and with great care until the lorry was situated in front of the conveyor belt.
With the liner safely delivered to site the project hit a major snag: the sensor on the conveyor belt failed. With the help of the staff from Brandenburger, Marc Albrecht was able to solve the problem quite quickly, allowing the folded liner to be drawn into the sewer without any further difficulties.
By the late afternoon the pipe liner was inflated and in position. Manuel Geißler, application engineer from Brandenburger, gave the go-ahead for the light chains with twelve UV lamps at a power of 1000 watt each, which were drawn through at 60 cm/min to cure the materials.
Inspection of the liner during the next morning confirmed that the €400,000 (US$420,000) rehabilitation project had been completed successfully. Reflecting on the project, Michael Schloder, Managing Director of Brandenburger, said, “We are quite proud that we could achieve the installation of a liner of this size. Our employees have completed a big job and proven how important good preparation and flexibility is on site.”
Grzegorz Owczarek, managing director of AKWA, was also happy with the successful conclusion of the major project, and reported that a member of the staff from the Krakow water works visited the construction site and complimented them on its successful completion.
For more information visit the Brandenburger website.
This article was featured in the Winter 2017 edition of Trenchless International. To view the magazine on your PC, Mac, tablet, or mobile device, click here.
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