Working in trenches and excavations can be one of the most dangerous construction operations. Soil cave-ins pose the greatest risk, but there are other potential hazards, including falls into the trench, loads falling and striking workers, hazardous atmospheres present, and being struck by mobile equipment. The Occupational Safety and Health Administration (OSHA) has an Excavation and Trenching Standard in place that is designed to protect workers from these hazards when it is adhered to. OSHA defines an excavation as any man-made cut, cavity, trench, or depression in the earth’s surface formed by earth removal. A trench is defined as a narrow underground excavation that is deeper than it is wide and is no wider than 15 feet. Listed below, please find some of these standards and requirements.
Determine the soil classification and requirements for the soil type (A, B, or C).
Call 811 before you dig; this will request that utility companies or owners determine the location of underground utilities before excavating.
Dig a minimum of 5 feet away or as state law permits away from marked utilities.
If the trench is 4 feet in depth or greater, then ensure proper sloping, benching, or shoring is in place.
If the trench is 20 feet in depth or greater, then ensure engineering protective systems are in place.
Ensure that underground installations are protected, supported, or removed while the excavation is open.
Keep heavy equipment away from the trench edges and identify other sources that may affect the stability of the trench.
Keep all spoil piles and equipment at least 2 feet away from the trench edges.
Use stairs, ladders, or ramps every 25 feet to exit the trench.
Do not work in trenches where water is standing or accumulating unless special supports are used to prevent cave-ins.
Test for atmospheric hazards such as low oxygen, hazardous fumes, and toxic gases when greater than 4 feet in depth.
The Trenching and Excavation Standard requires that a competent person inspect the jobsite trenches daily, as the conditions may change before workers enter the trench, and to be onsite whenever excavation or work is being performed.
Adherence to these standards ensures workplace and trench safety. Please refer to the online OSHA guidelines for further information.