Page 470 - Trenchless Technology Piping Installation and Inspection

420 App endix D

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 counterbalance
to earth pressures 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
counterbalance of earth pressures is supplied by pressurized drilling
fluid.
Earth pressure balance shield: Mechanical tunneling shield that uses a
full face to support the ground in front of the shield and usually employs
an auger flight to extract the material in a controlled manner.
Emergency repair: An unscheduled repair that must be made during a
pipe failure or collapse. This type of repairs may cost many times (usually
10 times more, not including social costs) of planned repair costs and may
not be as effective and/or permanent.

Emergency stop: A red, manually operated push button that, when
activated, stops all functions of the machine.
Entrance pit: (1) See boring pit or drive shaft.
Entry/exit angle: Angle to horizontal (the ground surface) at which the
drill string enters or exits in forming the pilot bore in a horizontal
directional drilling operation.
EPDM (ethylene-propylene-diene monomer): Type of rubber that has excellent
resistance to ozone, sunlight, and oxygen. It also has excellent resistance
to acids, alkalis, and ketones. Plus, it has excellent heat resistance and
aging. However it has poor resistance to fuels and oils.

Epoxy: Resin formed by the reaction of bisphenol and epichlorohydrin.
Epoxy lining: A curable resin system based on epoxy resins.
Exfiltration: The leakage or discharge of flows being carried by pipes or
sewers out into the ground through leaks in pipes, joints, manholes, or
other sewer system structures; the reverse of infiltrations.
Exit pit: See reception shaft.
Exit shaft: See reception shaft.
Expander: A tool, which enlarges a bore during a pullback operation by
compression of the surrounding ground rather than by excavation.
Sometimes used during a pipe bursting process as well as during
horizontal directional drilling

Face stability: Stability of the excavated face of a tunnel or pipe jack
operation.
Felt: A material specially designed to soak up, hold, and transport resins
in place to produce a hard cured-in-place pipe.