Horizontal directional drilling is a key trenchless method, used for drillings under roadways, railways, sewers, rivers etc. It allows the pipe to follow a pre-defined trajectory and enables its correction during the drilling, thanks to its accurate real-time tracking of the boring head. A special drilling fluid is used for this mehtod, which makes it very efficient in clay. It is also one of the best choices in terms of time, budget and flexibility. This method finds wide application worldwide for the installation of gas, water, sewer pipelines and cable protection, made of HDPE or steel, with a diameter from 100mm up to 1000mm or even more. In some cases, high tension cables can be installed directly.
The technology consists of three steps: pilot hole boring, conducted between a starting pit and an end pit with a previously chosen directory, pre-reaming and pullback. The piloting is guided with an electronic emitter – receiver system. The drilling fluid fluid is used through the whole process to cool and lubricate the equipment and to strengthen the hole. If necessary, a pre-reaming with a backreamer is carried out, in order to prepare the hole for the desired pipe diameter. At the end the pipe is pulled back from the end towards the starting pit.