Horizontal Directional Drilling (HDD)

A surface-launched trenchless technology for the installation of pipes, conduits, and cables. HDD creates a pilot bore along the design pathway and reams the pilot bore in one or more passes to a diameter suitable for the product, which is pulled into the prepared bore in the final step of the process.

Horizontal Earth Boring

Auger boring, boring, and jacking; the use of auger boring machines to prepare holes by the installation of a casing whereby the spoil is removed by the use of augers.

Horizontal Earth Boring Machine

A machine used to bore horizontally through the earth by means of a rotating tool, or nonrotating pushing or piercing tool.

Horizontal Rotary Drilling

The mechanical installation of pipe or casing by rotating methods which do not use augers for the removal of spoil. Usually uses a fluid of water and bentonite to remove spoil.

Host Pipe

The tube which carries the product being transported and which may go through casings at highway and railroad crossings. It may be made of steel, concrete, clay, plastic, ductile iron, or other materials. On occasion it may be bored direct under the highways and railroads.