HORIZONTAL DIRECTIONAL DRILLING (HDD) is a pipeline installation method that utilizes a drill rig to install the product pipe with virtually no excavations being necessary.
The drill rig sets up and launches from the surface and pushes drill pipe into the ground to establish the pathway for the product pipe to be installed.
The location of the drill pipe is monitored through the use of a locating device at the front of the drill head. Once the operator knows where the drill head is, he then controls what direction the drill head goes in by alternately thrusting and rotating the drill pipe in predetermined directions. Once this pilot bore is done and a path had been established for the installation of the pipeline, the hole is then enlarged through reaming. This process may be done as many times as is necessary to create a hole large enough to pull in the final product pipeline.