Trenching-
Trenching is a form of excavation in which a large hole is dug; the hole itself is usually quite deep but not very wide, and it is often dug to be long. Trenching is common in construction, especially when installing underground pipes, wires, or structural supports.
Excavation-
Excavation is the process of moving earth, rock or other materials with tools, equipment or machinery. It includes earthwork, trenching, wall shafts, tunneling and underground. Excavation has a number of important applications including exploration, environmental restoration, mining and construction.
Conduit Installation-
Conduit may be installed underground between buildings, structures, or devices to allow installation of power and communication cables. An assembly of these conduits, often called a duct bank, may either be directly buried in earth, or encased in concrete (sometimes with reinforcing rebar to aid against shear forces).