I want to discuss safety with you today, we know how dangerous excavating and shoring operations can be, and in fact statistics show they are some of the most hazardous in the construction industry. However, most of these hazards can be eliminated from the jobsite with proper work and safety techniques. All persons involved in excavation and shoring operations must be properly trained in safe work methods and practices and be able to recognize unsafe conditions when they occur.

The most common hazards of excavation and shoring operations are:

• Death by suffocation or crushing

• Tools or equipment striking utilities

• Materials or tools falling into the trench

• Personnel falling into the trench

• Personnel working too close together

• Hazardous atmospheres Death by suffocation or crushing – Proper sloping, benching, or support.

Trench cave-ins are the leading cause of death in trenching operations. Death may be caused by suffocation, but the force of a trench wall collapse has been known to embed the bodies of workers up to 12 inches into the opposing wall of the trench. Several factors can contribute to trench cave-ins and all should be addressed and safeguarded against in any trenching operation.

The instability of soil which leads to cave-in may be either a natural property such as loose sandy soil, or the drying of previously stable soil as a result of being exposed by excavation. Instability may also be a result of external factors such as vibrations from traffic or machinery, pressure from heavy equipment or machinery, or adjacent structures.

Safeguarding against cave-ins is accomplished by proper sloping or benching of trench walls, or proper support of walls by shoring or shielding. It is the law that one of these precautions be used on all trenches unless the excavation is made entirely in stable rock or the excavation is less than 5 feet in depth and has been examined by a competent person to ensure there is no potential for cave-in. Soil type must be known in order to determine which system or angle of slope to use, and should be determined by a trained competent person who must identify and classify the soil type.

I believe sloping of trench walls is the simplest way to ensure the safety of employees in a trench. However, sloping requires a significant increase in the volume of material to be excavated and stock-piled.

• Sloping for trench walls 20 feet or less in depth varies as follows:

• Soil Type A: ¾ : 1,