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Safety & OSHAaka: trench protectionaka: excavation shoring

Trench Safety

In Plain English

The safety measures required to prevent trench walls from collapsing on workers.

Definition

Trench safety refers to the protective systems and procedures required by OSHA 29 CFR 1926 Subpart P to prevent cave-in fatalities and injuries in trenches, which are excavations where the depth exceeds the width at the bottom. Protection methods include sloping to a safe angle, benching, shoring with timber or hydraulic shores, or using a trench box (pre-manufactured shielding system). Trenches must be inspected by a competent person daily and after any rainfall.

Why It Matters in Bidding

Trench protection is a direct, measurable cost line that excavation estimators must carry, whether through rental of trench boxes, hydraulic shoring, or the added excavation volume and haul cost of sloping. On public work, trench safety is frequently a separate mandated pay item, and omitting it or the required competent-person inspections exposes a contractor to citations, stop-work orders, and severe liability.

Example

Bidding a 9-foot sanitary line, an estimator prices trench box rental, the competent person's daily inspection time, and the extra spoil handling that benching adds rather than assuming open-cut excavation.

Related Terms

Excavation SafetyCompetent PersonOSHASite Safety Plan

Related Tools & Templates

Trench Safety Checklist

Frequently Asked Questions

OSHA requires a protective system for trenches 5 feet deep or greater unless the excavation is entirely in stable rock. For trenches over 20 feet deep, a registered professional engineer must design the protective system. Estimators should price protection by depth and soil class as defined in 29 CFR 1926 Subpart P.
Price the chosen protective method against trench depth, length, and soil classification. Sloping or benching adds excavation, spoil handling, and right-of-way; trench boxes or shoring add rental, mobilization, and crane time. Always include the competent person's daily and post-rainfall inspection labor, which is a required, billable cost.
A competent person is someone trained and authorized to identify trench hazards and stop work to correct them. They must inspect the excavation daily, before each shift, and after rain or changing conditions. Estimators should account for this person's time, since the role is mandatory and cannot be skipped to save labor.

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