Excavations and Trenching
The excavation standards
1926.651 covers surface conditions and 1926.652 covers protective systems. A competent person must inspect excavations daily before work begins and after any rainstorm or event that could change conditions. Protective systems - sloping, benching, shoring, or shielding - are required at 5 feet or deeper unless the excavation is entirely in stable rock.
Numbers that get tested
Soil classification drives the slope: Type A at 3/4:1, Type B at 1:1, Type C at 1.5:1, and Type C is never benched. Spoil piles, materials, and equipment stay at least 2 feet back from the edge. A ladder or other means of egress is required in trenches 4 feet or deeper and must be within 25 feet of lateral travel, extending 3 feet above the excavation. Test for oxygen deficiency and hazardous atmospheres where they may exist, and ventilate.
Utilities and water
Call 811 before digging, respect the locate marks, and hand-dig within the tolerance zone. Control water with dikes, ditches, and pumps, and never work in standing water without assessing stability. Provide high-visibility vests and barricades where mobile equipment operates near the edge. Stop work and re-inspect if you see tension cracks, bulging, or a change in conditions.
Traps
The 5-foot protective-system trigger is confused with the 4-foot egress rule. A trench is an excavation deeper than it is wide, with a bottom width of 15 feet or less. Type A soil is not a license to skip protection at depth.
Rule of thumb: five for a protective system, four for a ladder, two back for spoils, twenty-five to reach the ladder.