Close-Fit rehabilitation at Lake Attersee, Austria

In September 2012, quick rehabilitation was needed for 150 metres of sewage pipe with diameters of 300 mm on the shores of Lake Attersee, a popular holiday destination in the Salzkammergut region of Austria. With their Close-Fit liner, SPR Europe was able to provide the optimal solution.

150 metres of pipe-in-pipe in no time at all – and a defect wastewater sewer in the network of the Attersee Region (Reinhaltungsverband Attersee) was rehabilitated and brought into shape for the next decades. In September 2012, SPR Europe used the Close-Fit method to rehabilitate the sewer with diameters 300 mm, which was showing signs of breaks and cracks in the brickwork after a pipe inspection. At the location directly on the shores of the tourist destination Lake Attersee in the town of Steinbach, trenchless renovation was the economical and technical best solution for rehabilitating the sewer in the specified narrow time frame and without major impact on the heavy daily traffic.

Taking into account the criteria – time frame, condition of the existing pipe, construction site surroundings, nominal width and length of the rehabilitation section – the Close-Fit method presented the ideal technology. The breaks and cracks would normally make preliminary sealing necessary. This is where the Close-Fit liner offers a distinct advantage, as depending on the flow level, this step is not necessary. Installation of the liner can be started without delay.

Structurally self-supporting pipe-in-pipe

With the help of a traction limited winch and using a normal manhole, a four-man team from the Rabmer construction company, a subsidiary of SPR Europe, installed the pre-shaped PE pipe in the 150-metre length of sewer in two days. The deformation reduces the diameter of the new pipe by 25-30%, making it much easier to pull it into the damaged pipe. With the help of hot steam and pressure, the Close Fit liner was brought back into its original circular shape and pressed against the host pipe, without an annular gap. The new structurally self-supporting pipe within the pipe can withstand operating pressures of up to 12 bar and can withstand even higher pressures in combination with the host pipe. In the following two days, rehabilitation was performed manually on the manholes as well as the connections to the manholes, where pressure was applied to eliminate the annular gap between the liner and the host pipe. Many visitors came to the open house event to learn more about the success of the Lake Attersee rehabilitation project and the Close-Fit liner technology. The customer was able to put the rehabilitated sewage pipe into operation - a pipe built to last, with a new, outstanding level of hydraulic performance.

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