Pipe Express: fast installation through groundwater
Herrenknecht’s newly developed semi-trenchless method for pipeline installation has completed its third successful mission. South of Stockholm, using Pipe Express, Züblin Scandinavia AB installed a water pipeline more than a kilometre in length within 12 days. Groundwater lowering was not required despite a water level just below the terrain’s surface. Compared to conventional open cut construction the method has significantly less impact on the environment, while simultaneously minimizing costs.
Groundwater lowering not necessary
The benefits were obvious to Mats Ohlsson, project manager of client Stockholm Vatten: “For open-cut construction we would have needed sheet piles and we would have had to lower the groundwater.” The Pipe Express method from Herrenknecht, however, requires no lowering of the groundwater. The construction company made the most of this enormous budget and time advantage. It used Pipe Express for the laying of a 1,036-metre-long section of a 48-inch water pipeline near Huddinge, some 10 kilometres south of Stockholm. After drilling started on February 22, on March 5, 2015 the destination had already been reached. In the most productive 12-hour shift, 221 metres of pipeline disappeared into the ground; the average construction performance was 0.7 metres per minute. About 60 percent of the construction time was taken up just with welding and coating the up to 224-metrelong steel pipe strings.
Michael Lubberger, senior product manager pipeline at Herrenknecht, is proud of the success in Sweden: “After the pilot project in the Netherlands and the subsequent deployment in Thailand, this is already our third drive with Pipe Express. We see strong potential for the new method on the pipeline market.” The keen interest of international specialists on the site confirms this view.
Setting new standards for installing pipelines
Pipe Express from Herrenknecht is a new, semi-trenchless near-surface pipeline installation method. In this method, a buggy with a trenching unit creates a narrow, approximately 40-centimetre-wide trench on the surface. Below it in the soil a boring machine is mounted that digs the actual tunnel with diameters of up to 1.5 metres and lays the pipeline at the same time. The excavated soil is brought to the surface by the trenching unit and backfilled in the trench again behind the machine, laborious finishing work is not required. The pushing force for both excavation unit and pipeline is provided by a Herrenknecht Pipe Thruster located at the starting position.
In contrast to the conventional construction method the corridors, including construction paths, are up to 70 percent narrower. Extensive earthworks, groundwater lowering, the ramming of sheet piles etc. are not necessary. Up to 2,000-metre-long pipelines with a diameter of 900 to 1,500 millimetres (36 to 60 inches) can thus be laid quickly and cost-efficiently.