There are four ways to protect workers from cave ins on an excavation site: sloping, benching, shoring and shielding. The method chosen will depend factors including, but not limited to, soil type, water content, excavation depth and width, the nature of the work, and any nearby activities that could increase the likelihood of a cave-in. This determination must be made by a competent person on site.
If an excavation is more than 20 feet deep, a registered, professional engineer should design a protective system for the excavation site.
Sloping and benching involves removing the material from the face of an excavation at an angle to the floor. The flatter the angle between the face and the floor, the more protection afforded. If the slope is now deeper than 1.5 feet back for every foot of depth, it will be safe for all soil types.
Shoring and shielding systems prevent cave ins. Shores are vertical or horizontal supports that prevent the face from collapsing. They are easy to install and relatively inexpensive. Shields protect workers in the event that a cave in does occur. They are placed in the excavation by heavy equipment, come in a variety of dimensions and are usually made from aluminum or steel