Hazards: Cave-in and burial · Falling or rolling spoil and equipment · No safe way out of the trench · Hazardous atmospheres and water accumulation · Struck-by mobile equipment at the edge
Why it matters
OSHA's trench collapse alert puts it plainly: it only takes seconds to become buried in thousands of pounds of soil. CPWR's May 2024 Data Bulletin reports that OSHA counted 39 workers killed during trench or excavation work in 2022, up from 15 the year before, with construction accounting for roughly 85% of fatal trenching injuries from 2011 to 2021.
Key points
- 5 feet is the line. 1926.652(a)(1): every employee in an excavation gets an adequate protective system. Two exceptions only — entirely stable rock, or under 5 feet after a competent person examines the ground and finds no indication of a cave-in.
- Under 5 feet is not a free pass. Somebody qualified has to look and say so. "It's only four and a half" is not that examination.
- Slope it, shore it, or shield it. Cut the walls back, put shoring in, or set a box. And a box only protects the people inside it — step out to make a connection and you are in an unprotected trench.
- No soil classification? Cut 1 1/2 to 1. 34 degrees, no analysis needed, per 1926.652(b)(1)(i) — 12 feet back on each side at 8 feet deep. Past 20 feet, sloping has to be designed by a registered professional engineer.
- A way out within 25 feet. In trenches 4 feet or deeper, a ladder, stair or ramp no more than 25 feet of lateral travel away — 1926.651(c)(2).
- Spoil and equipment 2 feet back. 1926.651(j)(2). The pile at the lip is a surcharge load on the wall, and it rolls in on top of you.
- Inspected today, not last week. A competent person inspects before the start of work, as needed through the shift, and after every rainstorm — 1926.651(k)(1).
- Signs of distress mean everybody out. Fissures in the face, the edge subsiding, material slumping or bulging from the bottom. Out first, talk after.
Do / Don't
Do
- Know the depth and the protective system before anyone goes in.
- Keep the ladder in the trench and moved with the work.
- Call the competent person back after rain, a vibration source, or any change.
Don't
- Enter a trench to "just grab something" with no protection.
- Park the excavator or stack pipe at the edge.
- Work outside the shield or below an unsupported face.
Quick site check
- Walk today's trench together: depth, soil type, protective system.
- Ladder in place, within 25 feet of anyone working?
- Spoil, pipe and equipment a full 2 feet off the edge?
- Who inspected it this morning, and what did they find?
Discussion — ask the crew
- The trench we are opening today: how deep is it going, and what is the protective system before anyone steps in?
- Who is the competent person on this excavation, and does everyone here know their name?
- If a wall started to spall while you were in there, where is the ladder and how many steps away is it?
- It rained overnight. What has to happen before the first person goes back in this morning?
- Where is our spoil pile right now, and is it a full two feet off the edge?
Refs: 29 CFR 1926.652 — Requirements for protective systems · 29 CFR 1926.651 — Specific excavation requirements · 29 CFR 1926 Subpart P Appendix B — Sloping and Benching (Table B-1) · OSHA — Trenching Safety: 5 Things You Should Know to Stay Safe (Publication 3974, 2019) · OSHA — Trench Collapses Can Be Deadly (Alert, Publication 3971, 2022) · CPWR — Data Bulletin, Trenching Injuries, Citations and Penalties in Construction (May 2024)Sign-in sheet included in the printed version