Page 4 - Trench and Excavation

Glossary of Excavation Terms

Accepted Engineering Practices- those requirements, which are compatible with the standards
of practice, required by a registered professional engineer.
Actual Slope- the angle to which and trench face is excavated.

Adjacent- the area within a horizontal distance from the edge of the trench equal to the depth of
the trench.

Aluminum Hydraulic Shoring- Pre-engineered shoring system comprised of aluminum
hydraulic cylinders, used in conjunction with vertical uprights and/or horizontal rails (wales).

Angle Of Repose- the steepest angle at which the internal friction and cohesiveness of the soil
will keep it from flowing.
Apparent Cohesion- A weak cohesive force generated by the surface tension and capillary
action of water, which allows moist granular soil particles to stick together.
Appendix A- The part of CFR 1926 Subpart P which deals with soil testing. This appendix is
mandatory only if it is used.
Appendix B- The part of CFR 1926 Subpart P which deals with sloping and benching systems.
This appendix is mandatory only if it is used.
Appendix C- The part of CFR 1926 Subpart P which deals with timber shoring systems. This
appendix is mandatory only if it is used.
Appendix D- The part of CFR 1926 Subpart P which deals with aluminum shoring systems. This
appendix is mandatory only if it is used.
Appurtenances - Parts of a water main structure necessary to allow it to operate as intended
(e.g., hydrants, valves, and elbows). These parts are not considered as part of the main structure
itself.

Backfill- Material which fills the trench from the bedding to the top of the trench.
Bedding- Material which surrounds the pipe or which the pile lies upon.
Bell-Bottom Pier Hole- An excavation where the top cross-section is narrower than the bottom
cross-section.
Benching- A method of protecting employees from trench cave-in by excavating the sides of an
excavation to form one or a series of horizontal levels or steps with vertical or near vertical
surfaces between levels.

Berm- A mound of earth, which is molded and compacted into a long, narrow path commonly
used to channel water.

Caliche - A natural encrustation of calcium carbonate and dry, stony soil.
Cave-In- The separation of a mass of soil or rock material from the side of an excavation or the
loss of soil from under a trench shield or support system. This mass suddenly moves into the
excavation and can immobilize an individual and/or producing injury.
Cemented Soil- A soil where the particles are held together by a chemical agent (e.g., calcium
carbonate) such that a hand-sized sample cannot be crushed by finger pressure.
Clay- Soil mass composed of mineral particles less than 0.002mm in diameter.

Close Sheeting- The side-by-side placement of non-interlocking sheeting planks.

Trench & Excavation
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