What are the hazards of trenching and excavation work?
Cave-in The most common serious hazard is a cave-in. Workers can be killed or seriously injured if the sides of a trench or other excavation collapse. Cave-ins are most often caused by: • Vibration from construction equipment or traffic in the construction area that makes the soil come apart. • The weight of equipment that is too close to the edge of the trench can cause a collapse. The weight of the earth that has been removed (spoil bank) can also put a dangerous strain on the trench walls. • Soils that do not hold tightly together are more likely to collapse. For example, sandy soils are not cohesive and can easily slide back into a trench. By contrast, clay usually holds up well. • Soil that has been dug before is not as stable as earth that has not been previously disturbed. Work on utility lines involves digging previously disturbed soil. • Water weakens the strength of the trench sides. Rain can also be a hazard by either putting too much weight on the walls or filling the trenc
