DD – directional drilling – The practice of drilling non-vertical wells.

Geothermal energy – Heat is a form of energy and geothermal energy is, literally, the heat contained within the Earth that generates geological phenomena on a planetary scale.

Geothermal radial drilling – Method used to install ground heat collectors and borehole heat exchangers.

GPR – ground penetrating radar – This is a geophysical method that uses radar pulses to image the subsurface.  This non-destructive method uses electromagnetic radiation in the microwave band (UHF / VHF frequencies) of the radio spectrum, and detects the reflected signals from subsurface structures.

GPS – Global positioning system.

HDD – horizontal direction drilling – This is a steerable trenchless method of installing underground pipes, conduits and cables in a shallow arc along a prescribed bore path by using a surface launched drilling rig, with minimal impact on the surrounding area.

Pipe bursting – This is a trenchless method of replacing buried pipelines such as sewer, water, or natural gas pipes without the need for a traditional construction trench. “Launching and receiving pits” replace the trench needed by conventional pipe-laying.

Pipe Jacking – This is a method of tunnel construction where hydraulic jacks are used to push specially made pipes through the ground behind a tunnel boring machine or shield.  This technique is commonly used to create tunnels under existing structures, such as roads or railways.

Topographical survey – A survey of the surface shape and its features.