The contractor Salzmann Erd- und Betonbohrungen from Oberstetten, Canton St. Gallen, Switzerland has used its directional HDD drilling machine TERRA-JET TJ 1804 S to lay a gas line in the city Sirnach. Therefore the HDD machine was installed directly on the road, which was blocked due to the open trench for the main gas pipeline. The directional pilot bore was 49 m (160 ft) long. After 20 m (66 ft) an existing telecom cable had to be undercrossed. During backreaming a HDPE pipe OD 125 mm (5”) was pulled in.
The HDD machine TERRA-JET TJ 1804 S is equipped with 2 m (6.6 ft) long drill rods, which allow a minimum bending radius of 25 m (82 ft). The torque of 1’800 Nm (1‘350 ft.lbs) and the thrust and backream force of 40 kN (4 tonnes, 8’800 lbs) allow bore channels up to ø 200 mm (8 ft).
It was not possible to position the HDD machine at the higher end of the bore. Therefore the bore started at the lowest point. The drill rods had to be bent upwards by 9 % per drill rod.
The drill head reaches the arrival pit right on target. The backreamer
ø 160 mm ( 6.3“) and the HDPE pipe ø 125 mm (5“) are assembled and pulled in.
The mixing and pumping station, the drilling fluid tank and the tools are installed on the trailer. This allows easy mixing of the Bentonite into the drilling fluid.
The complete 49 m (160 ft) long bore including pipe pulling took half a day.