With the construction of a new north-south pipeline connection, Poland is reacting to the increasing local demand for gas. Part of this network expansion is the >>Czeszów-Wierzchowice Gas Pipeline Project<< in the southwest of the country. So far, only HDD technology (Horizontal Directional Drilling) had been used for crossing rivers or roads during pipeline projects in Poland. Used for decades, the method has proved its worth for large numbers of boreholes, but it reaches its technical and economic limits in heterogeneous, non-stable grounds.

The sandy, sticky clay of the pipeline crossings in Wierzchowice and Czeszów presented just such geological conditions. Furthermore, the two alignments with lengths of 700 and 464 meters respectively run along existing gas lines. Uncontrolled deviations during the drilling process thus had to be avoided at all costs. All of these parameters pointed towards the first time use of the innovative Direct Pipe® technology from Herrenknecht. This method combines the advantages of microtunnelling and HDD technology. In a single step the required borehole is created and the prefabricated pipe is simultaneously installed without a trench.

Thanks to the gyrocompass navigation system which allows for an exact steering of the TBM, the drilling crew precisely installed the two pipelines with an outer diameter of 1,047 millimeters underground in just 13 respectively 16 drilling days. In doing so, they safely crossed, among others, beneath an ecologically sensitive fish pond. The sticky ground that typically tends to cause blockages is not a barrier for the Direct Pipe® method. Even at very high levels of friction resistance, the 500 tonnes of thrust provided by the Pipe Thruster in the launch shaft is more than enough. Overall, a very positive conclusion was drawn after successful completion of the project in October 2016 with daily best performances of 147 meters.