Page 476 - Trenchless Technology Piping Installation and Inspection

426 App endix D

Locator: An electronic instrument used to determine the position and
strength of electro-magnetic signals emitted from a transmitter (sonde) in
a directional drilling operation, or from existing underground services,
which have been energized, thereby identifying its location. In horizontal
directional drilling it is referred to as a walkover system.
Machine upset: The inadvertent action of a horizontal auger boring
machine that rotates the machine and track from its normal and upright
position to another position.
Man-entry: Also worker-entry, describes any inspection, construction,
renewal or repair process, which requires an operator to enter a pipe,
duct, or bore. OSHA currently has no minimum size limit for worker-
entry operations; however, they address a much broader concept of
confined space in Title 29 Code of Federal Regulations Part 1910.146. The
minimum size for which this is currently permissible in the United
Kingdom is 900 mm (approximately, 36 in.). Many trenchless technologies
do not require worker-entry inside the pipe.
Manhole: A structure that allows access to the sewer system.
Manual inspection: Method of sewer inspection that usually involves
physical entry and hands-on examination.

Microtunneling: A trenchless construction method for installing pipelines.
Microtunneling uses all of the following features during construction:
(1) Remote controlled––The microtunneling-boring machine (MTBM) is
operated from a control panel, normally located on the surface. The
system simultaneously installs pipe as spoil is excavated and removed.
Personnel entry is not required for routine operation. (2) Guided––The
guidance system usually references a laser beam projected onto a target
in the MTBM, capable of installing gravity sewers or other types of
pipelines to the required tolerance, for line and grade. (3) Pipe jacked––
The process of constructing a pipeline by consecutively pushing pipes
and MTBM through the ground using a jacking system for thrust.
(4) Continuously supported––Continuous pressure is provided to the
face of the excavation to balance groundwater and earth pressures.
Microtunnel boring machine (MTBM): See microtunneling.
Midi-HDD: Steerable surface-launched horizontal directional drilling
equipment for installation of pipes, conduits, and cables. Applied to
intermediate sized drilling rigs used as either a small directional drilling
machine or a large guided boring machine. Tracking of the drill string
may be achieved by either a downhole survey tool or a walk-over
locator.
Mini-horizontal directional drilling (Mini-HDD): Small diameter horizontal
directional drilling. In Europe it is called guided boring.
Mixed face: A soil condition that presents two or more different types of
material in the path of the bore.