Wale

Guide or brace of steel or timber, used in trenches and other construction.

Walkover System

See LocatorAn electronic instrument used to determine the position and strength of electro-magnetic signals emitted from a transmitter sonde in the pilot head of a boring system, in an impact moling tool or from existing underground services which have been energized. Sometimes referred to as a Walkover System..

Wall

Also riser. The vertical section between the bench and the cone of a manhole.

Washover Pipe

A rotating drill pipe of larger diameter than the pilot drill pipe and placed around it with its leading edge less far advanced. Its purpose is to provide stiffness to the drilling pipe in order to maintain steering control over long bores, to reduce friction between the drill string and the soil and to facilitate mud circulation. See Directional DrillingA steerable system for the installation of pipes, conduits and cables in a shallow arc using a surface launched drilling rig. Traditionally the term applies to large scale crossings in which a fluid-filled pilot bore is drilled using a fluid-driven motor at the end of a bend-sub, and is then enlarged by a washover pipe and back reamer to the....

Waste Ejector

See Spoil EjectorA set of paddles, rotating in close proximity to the inside of the casing pusher..