Requirements for Excavations [29 CFR 1926 Subpart P]
According to OSHA, excavating is one of the most hazardous construction operations. It is also the most frequently cited violation when OSHA conducts inspections of construction sites. The primary hazard of trenching and excavation is employee injury from collapse. Therefore, it is essential that engineering controls, protective equipment, and safe work practices be implemented to minimize hazards for workers who will enter trenches or excavations at their job sites. OSHA requires that all excavations 5 feet or deeper make use of one of the following protective system options: sloping the ground; benching the ground; shoring the trench with supports (e.g., planking or hydraulic jacks), or shielding the trench (e.g., using a trench box).
Excavations of 5 feet or deeper must meet OSHA's requirements at 29 CFR 1926 Subpart P (i.e., 29 CFR 1926.650, 29 CFR 1926.651, and 29 CFR 1926.652). These regulations provide employers with criteria for classification of soil types, selection of employee protection methods, use of performance criteria, and safe access requirements (such as having a ladder or ramp, and having excavated material be placed more than 2 feet away from an excavation edge).
Soil type, water content of soil, environmental conditions, proximity to previously backfilled excavations, weight of heavy equipment or tools, and vibrations from machines and motor vehicles can greatly affect soil stability and the potential hazards of a job site. Workers should never enter a trench that does not have a protective system in place which was designed and installed by a competent person. A competent person understands OSHA regulations, can recognize hazards and is authorized to correct them, can select an appropriate protective system (e.g., benching cannot be used in Type C soil), can direct the installation of the protective system, and will conduct daily inspections of the job site and protective system.
Protective systems for excavations 20 feet or greater in depth must be designed by a registered professional engineer.
Trenching and excavation hazards are also addressed in specific standards for general industry and marine terminals. Detailed information on excavation hazards and safeguards is available online at http://www.osha.gov/SLTC/trenchingexcavation/index.html.
To learn more about this and other safety requirements, attend Environmental Resource Center's Safety Regulations - Webcast, the OSHA 10-Hour Compliance Course, or the Environmental, Health, and Safety Laws and Regulations seminar.