What is Horizontal Directional Drilling?

Horizontal directional drilling is an innovative trenchless technology that enables us to install underground utilities without conventional open trenching, as well as obtaining sub-surface information in areas previously inaccessible. Bores from 50mm (2") diameter to 900mm (36") diameter can be completed. The length and size of the bore varies depending on soil type and size of product being installed with this equipment.

The Benefits of Horizontal Directional Drilling
Fast, low cost and low impact on the environment
Directional drilling makes a horizontal borehole. Drilling begins with the boring of a small diameter pilot hole directed to and along a desired design profile using flexible drill rods. Sub-site electronics are used to monitor and track the bore location through a sensor located in the bore head below the surface. Directional changes are made to the drilling alignment and direction with a bore head, which is offset slightly from the drill rods. Through small adjustments by the operator, steering corrections throughout the bore can be made (for example, around tree roots, boulders, buried utilities or private property). A special drilling ´mud´ technology, borrowed from the oil and gas industry, is introduced into the hole to prevent it from caving as well as providing a lubricant and flushing medium for cuttings.

Following advancement of the pilot hole, a back reamer is attached and pulled back though the pilot hole in order to achieve the required diameter for the product pipe to be installed. Pipe casing may then be pulled through the bore into position and required connections made.

A good horizontal directional drilling video recommended as below
https://www.youtube.com/watch?v=FQBVTlcl20c&noredirect=1