Directional boring, commonly called horizontal directional drilling or HDD, is a steerable trenchless method of installing underground pipes, conduits and cables in a shallow arc along a prescribed bore path by using a surface-launched drilling rig, with minimal impact on the surrounding area. Directional boring is used when trenching or excavating is not practical. It is suitable for a variety of soil conditions and jobs including road, landscape and river crossings. Duct or continuous piping can be made of materials such as PVC, polyethylene, polypropylene, Ductile iron, and steel if the pipes can be pulled through the drilled hole.
Connectrix operates Vermeer 7/11 directional drills (7000lb thrust), rolling on independent transporters equipped with slurry tanks and multiple drill head assemblies. Capable of drill and pull back on pipes or ducting up to 150mm outer diameter.
Location and guidance of the drilling is an important part of the drilling operation, as the drilling head is under the ground while drilling and, in most cases, not visible from the ground surface. Uncontrolled or unguided drilling can lead to substantial destruction, which can be eliminated by properly locating and guiding the drill head.
There are three types of locating equipment for locating the bore head: the walk-over locating system, the wire-line locating system and the gyro guided drilling, where a full inertial navigation system is located close to the drill head. Connectrix employees the Walk-over locating system — In this system a sonde, or transmitter, behind the bore head registers angle, rotation, direction, and temperature data. This information is encoded into an electro-magnetic signal and transmitted through the ground to the surface in a walk-over system. At the surface a receiver (usually a hand-held locator) is manually positioned over the sonde, the signal is decoded and steering directions are relayed to the bore machine operator.