What is the OSHA Trench Definition

Project Managers Discussing OSHA Trench Definition and guidelines.

Excavation and trenching are among the most hazardous construction operations. OSHA trench definition is any man-made cut, cavity, trench, or depression in the earth’s surface formed by earth removal. Also, OSHA trench definition is defined as a narrow underground excavation that is deeper than it is wide, and is no wider than 15 feet (4.5 meters). Cave-ins pose the greatest risk and are much more likely than other excavation-related accidents to result in worker fatalities. Other potential hazards include falls, falling loads, hazardous atmospheres, and incidents involving mobile equipment. Trench collapses cause dozens of fatalities and hundreds of injuries each year.

Trenches 5 feet (1.5 meters) deep or greater require a protective system unless the excavation is made entirely in stable rock. Trenches 20 feet (6.1 meters) deep or greater require that the protective system be designed by a registered professional engineer or be based on tabulated data prepared and/ or approved by a registered professional engineer. There are different types of trench protective systems.

OSHA Trench Definition and Trench Workers

OSHA requires that workers in trenches and excavations be protected and that safety and health programs address the variety of hazards they face. Sloping involves cutting back the trench wall at an angle inclined away from the excavation. Shoring requires installing aluminum hydraulic or other types of supports to prevent soil movement and cave-ins. Shielding protects workers by using trench boxes or other types of supports to prevent soil cave-ins. Designing a protective trench shoring system can be complex because you must consider many factors: soil classification, depth of cut, the water content of the soil, changes due to weather or climate, surcharge loads (e.g., spoil, other materials to be used in the trench) and other operations in the vicinity.

OSHA trench definition standards require that trenches be inspected daily and as conditions change by a competent person prior to worker entry to ensure elimination of excavation hazards. A competent person is an individual who is capable of identifying existing and predictable hazards or working conditions that are hazardous, unsanitary, or dangerous to employees and who are authorized to take prompt corrective measures to eliminate or control these hazards and conditions. OSHA requires safe access and egress to all excavations, including ladders, steps, ramps, or other safe means of exit for employees working in trench excavations 4 feet (1.22 meters) or deeper. These devices must be located within 25 feet (7.6 meters) of all workers. Workers are expected to keep heavy equipment away from trench edges, they have to know where underground utilities are located, and they also have to keep surcharge loads at least 2 feet (0.6 meters) from trench edges. They are expected to inspect the trenches at the start of each shift and test for low oxygen, hazardous fumes, and toxic gases.