ISSUES:
Trench collapses or cave-ins, pose the greatest risk to workers’ lives. When done safely, trenching operations can reduce worker exposure to other potential hazards including falls, falling loads, hazardous atmospheres, and incidents involving mobile equipment.
- Soil weighs between 90 and 140 lbs. per cubic foot. Therefore, one cubic yard (3 ft. by 3 ft. by 3 ft.) can weigh as much as a small pickup truck. If a person is buried, there is little chance of survival.
- There are many things that can affect soil stability, such as the type of soil, water, and vibration. Soils saturated with water and previously disturbed soils are very dangerous to work in or around. But don’t be fooled, even hard soil and rock that appears stable can cave in.
- About half of the people killed each year in trenches die trying to rescue someone else who has been buried by a cave-in. Call 911 for help. Do not attempt a rescue unless you have been properly trained in trench rescue techniques.
- Other hazards include falling objects, hazardous atmospheres, and exposure to mobile equipment and traffic.
- Remember, if you are buried by a cave-in, your chance of survival is very low. Therefore, always be sure that the trench walls are sloped, shored, or shielded with a trench box and that the trench is safe before you enter.
SOURCES OF HAZARDS:
- Lack of pre-planning and site visits.
- Improper protection systems.
- No assigned “Competent Person.”
- Not following engineer designs or manufacturer’s requirements.
- Working under loads or not keeping material from falling into the work area.
- Lack of Training.
REGULATIONS:
1926.651(a) Surface encumbrances. All surface encumbrances that are located so as to create a hazard to employees shall be removed or supported, as necessary, to safeguard employees.
1926.652(b) Design of sloping and benching systems. The slopes and configurations of sloping and benching systems shall be selected and constructed by the employer or his designer and shall be in accordance with the requirements of paragraph (b)(1); or, in the alternative, paragraph (b)(2); or, in the alternative, paragraph (b)(3), or, in the alternative, paragraph (b)(4).
1926.652(c)(2)(iii) Manufacturer’s specifications, recommendations, and limitations, and manufacturer’s approval to deviate from the specifications, recommendations, and limitations shall be in written form at the jobsite during construction of the protective system. After that time this data may be stored off the jobsite, but a copy shall be made available to the Secretary upon request.
1926.652(b)(3)(iii) At least one copy of the tabulated data which identifies the registered professional engineer who approved the data, shall be maintained at the jobsite during the construction of the protective system. After that time the data may be stored off the jobsite, but a copy of the data shall be made available to the Secretary upon request.
1926.651(f) Warning system for mobile equipment. When mobile equipment is operated adjacent to an excavation, or when such equipment is required to approach the edge of an excavation, and the operator does not have a clear and direct view of the edge of the excavation, a warning system shall be utilized such as barricades, hand or mechanical signals, or stop logs. If possible, the grade should be away from the excavation.
5 4 3 2 1 RULES FOR EXCAVATIONS.
- 5. 1926.652(a)– (c) Protective Systems Each employee in a trench/excavation shall be protected from cave-ins by an adequate protective system except when excavations are less than 5 feet in depth 4
- 4. 1926.651(c) Access and Egress Provide employees a means of access and egress when the trench is 4 feet or deeper. Ensure the means of access/egress are located within 25 feet of lateral travel of all employees working in the excavation.
- 3. 1926.651(c) Access and Egress Ladders must be secured and extend a minimum of 3 rungs (36 in) above the landing and tied off. In the event that no ladder is used, employees must be able to enter/exit the trench/excavation with less than 3 points of contact.
- 2. 1926.651(j) Spoil Piles and Equipment Provide protection from loose rock, soil, tools, and other items that may fall or roll into the excavation. Maintain a clear 2-foot area at the excavation edges.
- 1. 1926.650 Scope and Definitions Each trench/excavation must have a minimum of 1 competent person.
EXAMPLE INCIDENTS THE FACTS:
In the U.S., trenching kills on average 40 workers every year. Workers can suffer death or serious injury within minutes of being caught in a trench cave-in.
January 3, 2025: A miner in Borger Pit, Hutchinson County, Texas, died in a trench collapse. March 3, 2025: Two workers died in a trench collapse in Maryland.
EXAMPLE INCIDENTS THE FACTS:
- Pre-Planning is essential; including a site inspection before digging.
- OSHA requires that protective systems for excavations and trenches be designed by a registered professional engineer for any trench deeper than 20 feet.
- If the trench parameters or site conditions are not covered by OSHA standards (Appendices) or the manufacturer’s tabulated data (MTD), a site-specific engineered design is necessary. This applies to both shoring and sloping/benching systems
- Protective systems – (ex: Slope, Bench, Shore, or Shield excavations) are required where the soil or rock is unstable or prone to collapse and could cause injury to a person or trench or excavation is deeper than 4 feet.
- Provide adequate Access/Egress – never climb or allow climbing the sides of an excavation or trench.
- Management control of risk by supervision and control of work – allow no more personnel in the trench or excavation than is absolutely necessary to perform the task at hand. Minimize access of persons to an excavation.
- Do not work under suspended or raised loads and materials.
- Provide daily and ongoing inspections.
- Have a rescue plan. A written plan is recommended for deep excavations and is required for trenches over 20 feet deep.
- Wear high visibility or other suitable clothing when exposed to vehicular traffic inside the excavation or at edges or trenches and excavations.
- Hard barricades are the most effective protective system at excavation and trench edges.
- Competent Person Responsibilities:
- Ensure proposed excavation(s) have been marked for underground utility locating and contact utility locating service.
- Know and understand utility locating services and their markings.
- Classifying the soil type.
- Prescribe and ensure proper installation of protective system(s).
- Identify and correct all hazards, including those associated with confined spaces.
- Ensure employees are protected from the spoils, surface encumbrances, and all other potential hazards surrounding the excavation.
- Ensure adequate access and egress. Ensure proposed excavation(s) have been marked for underground utility locating and contact utility locating service.
- Ensure adequate access and egress.
- Ensure excavation is properly barricaded and protected from the public.
- Ensure atmospheric monitoring is performed when necessary.
- Perform daily trenching and excavation inspection (Prior to the start of work, as needed throughout the day, after rain or other event).
- Perform evacuation of exposed employee(s) from an excavation or trench if evidence of: a situation that could result in a possible cave-in, indications of failure of protective systems, or hazardous atmospheres. All employees shall be removed from the hazardous area until the necessary precautions have been taken to ensure their safety and/or other hazardous conditions.
WHAT YOU NEED TO KNOW:
- Planning and physical site inspections are required before digging and continuing operations on a daily basis.
- Who is your “Competent Person” on site? Do they understand the scope of their responsibilities listed in Number 12 in the previous section?
- Have all surface obstructions existing in the excavation or trench removed, supported, or have a written plan for removal before digging a trench or excavation?
- Is all the required tabulated data for all protective systems (Sloping, Benching, Shoring, or Shielding) on-site readily available? This can be as simple as knowing where the OSHA tabulated data is (utilizing 1926.652(c)) or having access to the engineered/manufacturer requirements.
Benching cannot be done in Type C soil.
- Do participate in or require that pre-planning be performed.
- Do require a “Competent Person” to perform a daily and ongoing evaluation. Ensure all workers know who that person is.
- Do enter trenches or excavations only that have been sloped at the proper angle, shored, or shielded.
- Do require that tabulated dates for support systems be on-site or readily available.
- Do require appropriate egress means, equipment, and procedures.
- Do check regularly for hazardous materials and oxygen levels in the trench.
- Do use a ladder or ramp to get in and out of the trench. Place the ladder inside the protective system.
- Do check that all spoil piles and materials are far enough away to prevent being struck by hazards.
- Do stay out from under raised loads
- Do be present mentally the entire time you are in a trench or excavation.
- Do prepare a rescue plan.
Here are important Don’ts to keep in mind about trenches and excavations:
- Don’t follow the “get it done” attitude and just dig in and go.
- Don’t utilize support systems without understanding the tabulated data (OSHA information, engineered design information, or the manufacturer’s specific utilization data.
- Don’t just climb in a trench or slide down the edges of an excavation.
- Don’t climb on shoring or shields. Never ride in equipment buckets or on crane hooks.
- Don’t store anything close to a trench excavation that could fall into the space.
