Successful drilling under the river Göta Älv using the walkover navigationsystem from Underground Magnetics Mag 8.
When the municipally of Vänersborg was going to extend the water network and build a new pipeline to Vargön and Vänersnäs they choosed the HDD method for crossing the river.
The drilling operation was undertaken by Styrud AB. Total length was 440 meter.
Of that length was approximately 300m under water. At the deepest point the depth was 22 meter.
This would be just on the level of what the existing competition might reach. Just to make sure and avoid locating problems the new Mag 8 delivered by Stingrock AB was choosen for the task.
– The conditions was quite challenging, says Anders Malm navigator for Styrud AB.
Measurement had to be done from a boat and above the normal current the release of excessive water from lake vänern 900m³ per second made it difficult to keep the boat in position to get readings.
– Normally you get a lot of interference which effects the signal from the transmitter. It can be electromagnetic interference from power, signal,lines, railway, tramway cathodic protection of constructions and a lot more, and the deeper the drilling has to be performed the capacity of the navigationsystem has to be of best class.
– With the Mag 8 signal was very good and it was never a problem to stay on line. This feels good for the future to have access to the Mag 8.