HDD, also known as horizontal directional drilling, is a technique typically used by Bothar for long crossings over waterways, gorges and environmentally sensitive areas where traditional trenching or excavating is not practical.

The HDD process commences with a small rotating and steerable drill bit being launched from the surface at an angle of 10-15 degrees which is used to drill a mud-filled pilot hole. A rotating barrel reamer is then attached to the drill head and pulled back by the drill string to enlarge the bore, drill mud being used to flush away the cuttings and to support the reamed hole. Subsequent reaming is repeated until the required diameter is achieved.

Bothar Boring’s HDD service permits the placing of pipes or conduits over considerable distances, without disturbing the surface or damaging the surrounding environment. This method of trenchless technology is suitable for laying water and wastewater pipes, gas, oil pipelines, and electricity and telecommunications cables and conduits. Bothar’s HDD size range is from 300mm – 1500mm in diameter with a maximum length of 2.5km.