No fear of large liner lengths: In Switzerland, ISS Notter Kanalservice installed a 257-meter long DN 600 liner in one day

Sewer rehabilitation with light-curing pipe liners are already characterised by fast installation times and few disadvantages for traffic and residents. In Bottmingen in Switzerland the objective was to prove that users of this method need not worry even if the liners are long. For the advantage is obvious: "You only have one installation and curing phase and roads are blocked only once with construction vehicles", explains Fabian Murmann, construction supervisor at ISS Notter Kanalservice referring to the advantages of this long rehabilitation segment. Normally, one would have divided this rehabilitation segment of nearly 260 meters into two segments, which would have meant that the construction phase would have lasted two days. Long lengths thus not only save time but also costs.

 

Before the start of the rehabilitation, a final camera inspection is performed. As part of the rehabilitation measure in Bottmingen, the main intercepting sewer from the local hospital to the treatment plant was rehabilitated with GRP pipe liners. The damage revealed showed leaking pipe couplings, joint fractures and an ovalisation of the old pipes of about three per cent.

 

 

For Mario Saalow, who accompanied the construction on behalf of RELINEEUROPE, the manufacturer of the slip liners, the prerequisite for the successful installation of the GRP liners of this length is the perfect coordination of the constructions crews and that the equipment for the curing phase has the sufficient capacity required for long lengths. In addition, the sewer pipe to be rehabilitated should be as straight as possible. These requirements were met in Bottmingen when, on 17 May 2011, the rehabilitation work began early in the morning at 7 am. The UV-curing system of the company ISS Notter Kanalservice had a usable cable length of 300 meters. Up to this length, it would theoretically have been possible to install a liner. The new control system of the UV-system developed and manufactured by RELINEEUROPE ensures that despite the length of the cable along the light train, each UV lamp has its fully capacity for the curing process of the liner.

 

Maximum care was required when preparing the pulling head of particularly long liners. Moreover, the four-strong men crew around construction supervisor Murmann was aware that, ideally, the Alphaliners with a total weight of 6.4 tons had to be pulled over the sewer pipe in a continuous and smooth manner. The liner was pulled directly from the lorry over the sewer pipe using a conveyor. In addition to the standard Preliner Foil, a biodegradable white oil was used to improve the lubricity of the pipe liner. The Swiss rehabilitation experts ensured in particular that the joining of the liner heads were performed "absolutely accurately" and that the straps were sufficiently tightened. The pulling force required to pull the liner over the pipe finally was only 1.6 tons.

 

Using a conveyor, the 257-meter long liner was pulled over the pipe in one go.No differences for the installation of shorter liners were evident in the following work. The liner was inflated and calibrated with air. Routine procedures also included the subsequent placing of packers at the liner ends and the installation of the light source for the curing of the 5.6 mm thick liner. With a curing capacity of nine times 1,000 watts, the curing process at a speed of 84 centimetres per minute took about five hours. At 10 pm on the same day the rehabilitation of the segment had been completed.

 

 

When deciding in a rehabilitation project whether to install liners over long segments exceeding 200 meters, Mario Saalow recommends that the users of the RELINEEUROPE Alphaliner method first of all conduct a thorough risk analysis; because liners of this length have a significant material value. "Contractors should not be afraid of using the services and technical support our company offers for their construction site. The customers can rely on the experience of our specialists from a number of construction sites and thus minimise the risk for their own project. Provided the conditions are given, nothing speaks against installing long liners and thus improving the efficiency of rehabilitation projects.