What’s the difference between a trench and an excavation? An excavation is a hole left in the ground as the result of removing material. A trench is an excavation in which the depth exceeds the width.
An unstable trench or excavation can collapse, killing or injuring workers by suffocation or crushing when a worker is buried by falling soil. Trench stability is affected by a number of factors such as:
- soil type
- surcharge (excessive weight near the trench)
- existing foundations
- previous excavation
The risk of a cave-in is not the only hazard in trenching. Injuries and deaths are also related to six other major areas:
- personal protective equipment
- utilities underground and overhead
- materials handling and housekeeping
- heavy equipment
- traffic control
- confined spaces
Before excavating, the gas, electrical and other services in the area must be accurately located and marked. If the service poses a hazard, it must be shut off and disconnected. Over half of all powerline contacts involve buried cable.