Trenches and excavations don’t need to be deep or large to create life-threatening hazards. Soil is extremely heavy, and failures can occur with little or no warning. A cubic yard of soil weighs about 2,700 pounds, and a cave-in can exert a force equivalent to dropping a small car from a foot above a person’s head. Workers can be trapped before they have time to react. For this reason, every trenching or excavation project must be carefully planned. 

KEY SAFETY PRACTICES

• Underground utilities: Identify and physically locate sewer, water, gas, communication and electric lines before excavation begins. Determine the estimated location of utility installations that reasonably may be expected to be encountered, and contact utility companies or owners during established local response times to have them locate the lines before work starts. If utilities cannot respond within 24 hours (unless state or local law requires a longer period) or cannot establish the exact location, you may proceed with caution and use detection equipment or other acceptable locating methods. 

• Overhead utilities: Ensure digging equipment has adequate clearance to avoid contact with overhead electric and communication lines, and plan work to maintain safe distances per applicable electrical safety standards. 

• Protective systems planning: Before excavation begins, evaluate the need for shoring, sloping, benching, shielding, or other protective systems to prevent cave‑ins. This evaluation must be done by someone familiar with soil classification, protective system requirements and OSHA standards (refer to 29 CFR 1926, Subparts P‑A and P‑B).

• Plan work carefully: If a job isn’t planned ahead of time, crews may take shortcuts to get the work done, putting themselves at serious risk. Soil may appear solid, but the condition behind trench walls cannot be seen. Excuses and shortcuts are unacceptable; all excavation work must be properly planned and executed to prevent unnecessary hazards.

• Trench protection requirements: All trenches and excavations 5 feet deep or deeper must be protected from cave-ins unless made entirely in stable rock. Protection can include sloping, benching, shoring/support systems, or trench shields/boxes. Trenches less than 5 feet deep may still require protective systems depending on soil type and site conditions.

• Shoring and trench boxes: When using shoring or trench boxes, the top must extend at least 18 inches above the trench. For extended projects with trenches deeper than 6 feet, fall protection should be installed around the perimeter to protect workers on the surface.

• Spoil placement: Excavated material must be placed at least 2 feet from the edge of any trench or excavation. Placing spoil closer can put pressure on trench walls and increase the risk of cave-ins. Workers should not be on the sides of sloped or benched excavations unless those below are protected from falling materials.

• Equipment and traffic: Take precautions to prevent vibrating equipment or traffic from causing a cave-in. Keep all equipment and vehicles away from trench edges.

• Groundwater hazards: Consider groundwater seepage as a potential cause of trench or excavation collapse. Workers must stay out of excavations where water is accumulating until proper protective measures are in place, which may include shoring, pumping, or the use of lifelines and harnesses.

• Heavy loads: Never allow workers under loads handled by lifting or digging equipment. Workers must stand clear of vehicles being loaded or unloaded.

• Means of exit: Any trench or excavation 4 feet deep or deeper must have a safe means of exit so workers never travel more than 25 feet to reach it. This can be provided by a ladder, ramp, or open end. Ladders should extend at least 3 feet above the surface and be secured or tied off if possible.