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Former OSHA investigator stresses trench safety: soil classification, competent person and engineering controls
Summary
John Young of the North Dakota Safety Council reviewed trench and excavation hazards, soil classification techniques, protective-system options (sloping/benching, shielding, shoring) and the role of the competent person, citing OSHA/ANSI guidance and emergency-response considerations.
John Young, a trainer with the North Dakota Safety Council and a former OSHA official, delivered a virtual presentation on trenching and excavation safety, covering soil classification, protective systems and on-site responsibilities. "No one can absolve themselves from their responsibility for safety by contract," Young said, urging field supervisors and engineers to proactively identify and correct hazards.
Young said the competent person is the central role in trench safety: they must identify existing and predictable hazards, perform soils analysis (manual or instrument-based tests) and have authority to correct unsafe conditions. He recommended asking three basic questions on any excavation: who is the competent person, how was the soil classified, and what protective system is in use.
Young outlined key regulatory and practical thresholds: a means of egress is required at 4 feet, and a protective system is generally required at 5 feet. He explained visual and manual soil-classification techniques (roll-the-soil ball, thumb penetration, ribbon/plasticity tests) and described type A, B and C soils and how that classification affects protective measures. He said type A soils are dense clays with higher allowable pressure, type B is an intermediate category, and type C behaves like loose granular material (beach sand) and offers the least stability.
On protective systems, Young described three approaches: sloping/benching (use of an angle of repose based on soil type), shielding (trench boxes designed to "take a hit" and protect workers from cave-ins) and shoring (systems that support exposed walls). He warned that shielding and shoring must be used per the engineer’s tabulated data and that employers must keep that tabulated data on-site for reference. He also cautioned about stacking trench boxes only when the manufacturer/engineer allows it and checking pinning and egress requirements.
Young used accident examples to stress urgency: a trench cave-in can crush or suffocate an employee quickly because a cubic yard of soil can weigh roughly 2,700–3,300 pounds and soil can move rapidly. He described emergency-response considerations, noting that many rural responders lack trench-rescue experience; competent persons should ensure contact lists and local rescue arrangements are in place.
Other practical items Young covered included spoil-pile placement (at least 2 feet from the trench edge), vibrations and water effects on soil strength, surface encumbrances (trees, poles) and utilities (call-before-you-dig/811). He recommended daily competent-person inspections, atmospheric testing where there is a risk of toxic vapors or oxygen displacement, and ensuring unobstructed egress ladders that extend at least 3 feet above the trench rim.
Young concluded by reiterating the three inspection questions and encouraging attendees to ask for tabulated data for shields or shores on site; there were no formal votes or policy actions during the training.
