Drive/Entry Shaft/Pit

Excavation from which trenchless technology equipment is launched for the installation of a pipeline, conduit or cable. It may incorporate a thrust wall to spread reaction loads to the soil.

Drop Connection Manhole

A manhole in which the influent pipe enters from above the effluent invert depth. If the drop occurs in the manhole itself, it is called an “internal” drop manhole. If the drop occurs a few feet upstream of the manhole, it is referred to as a “external” drop.

Drop Manhole

If the upstream pipe is at a greater elevation than the manhole invert then two inlet connections to the manhole are made. One is through the wall at the same grade as the upstream pipe, the other is at the invert so to direct flows through the channel. The invert connection is made by incorporating a pipe drop in the upstream pipe. The pipe drop may be outside or inside the manhole.

Dry Bore

Any drilling or rod pushing system not employing drilling fluid in the process. Usually associated with guided impact moling, but also some rotary methods.

Duct

(1) In many instances, a term interchangeable with pipe. (2) In the boring industry, it is usually used for small plastic or steel pipes that enclose wires or cables for electrical or communication usage. (3) ConduitA broad term that can include pipe, casing, tunnels, ducts or channels. The term is so broad that it should not be used as a technical term in boring or tunneling. inside which a utility service is installed.