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) Conduit inside which a utility service is installed.

DWF

Dry Weather Flow; is the base flow in a sewer prior to rain induced flows.

DWI

Dry Weather Inflow; is the result of flow entering the collection system from connected sources which are not caused by rainfall. Typically, this could include water from fire fighting, hydrant abuse, street washing, sump pumps etc.

Earth Piercing

The use of a tool that comprises a percussive hammer within a suitable, generally torpedo-shaped casing. The hammer may be pneumatic or hydraulic. The term is usually associated with nonsteered devices.

Earth Pressure Balance (EPB) Machine

Type of microtunneling or tunneling machine in which mechanical pressure is applied to the material at the face and controlled to provide the correct counter-balance to earth pressures in order to prevent heave or subsidence. The term is usually not applied to those machines where the pressure originates from the main Pipe Jacking rig in the Drive Shaft/Pit or to systems in which the primary counter-balance of earth pressures is supplied by pressurized drilling fluid.