11.4: Competent Person

A competent person is an individual, designated by the employer, who is capable of identifying existing and predictable hazards in the surroundings or working conditions which are unsanitary, hazardous or dangerous to workers, and who is authorized to take prompt corrective measures to eliminate them. Under the Excavation standards, tasks performed by the competent person include: Classifying soil; Inspecting protective systems; Designing structural ramps; Monitoring water removal equipment; and Conducting site inspections.

Why is preplanning important for excavation work?

No matter how many trenching, shoring, and backfilling jobs an employer has done in the past, it is important to approach each new job with care and preparation. Many on-the-job incidents result from inadequate initial planning. Waiting until after the work starts to correct mistakes in shoring or sloping slows down the operation, adds to the cost of the project, and makes a cave-in or other excavation failure more likely.

How can employers prevent cave-ins?

OSHA generally requires that employers protect workers from cave-ins by: sloping and benching the sides of the excavation; supporting the sides of the excavation; or placing a shield between the side of the excavation and the work area.

In many cases the type of protective system needed is well known and simple to use. At other times employers will undertake the more complex process of designing a protective system. Designing a protective system requires consideration of many factors, including: soil classification, depth of cut, water content of soil, weather and climate, and other operations in the vicinity. Employers are free to choose the most practical design that will provide the necessary protections. Any system used must meet the required performance criteria.

The Excavation standards describe various methods and approaches that can be used to design protective systems. Examples of protective systems that can be used to comply with the Excavation standards include:
■ Sloping the sides of the excavation to an angle not steeper than 1½:1 (for every foot of depth, the trench must be excavated back 1½ feet). A slope of this gradation is safe for any type of soil.
■ Designing a sloping and benching system in accord with tabulated data, such as tables and charts, approved by a registered professional engineer. This data must be in writing and must include enough explanatory information (including the criteria for selecting a system and the limits on the use of the data) for the user to be able to select an appropriate protective system. At least one copy of the data, which identifies the registered professional engineer who approved it, must be kept at the worksite during construction of the protective system. After the system is completed, the data may be stored away from the jobsite, but a copy must be provided upon request to an OSHA compliance officer.
■ Using a trench box or shield approved by a registered professional engineer or designed in accord with tabulated data approved by a registered professional engineer.

Image 11:1 Trench Slope and Shields. (Source: www.osha.gov, Public Domain).

The Excavation standards require employers to provide support systems, such as shoring, bracing, or underpinning, when necessary to ensure that adjacent structures (including adjoining buildings, walls, sidewalks and pavements) remain stable for the protection of workers. The standards also prohibit excavation below the base or footing of any foundation or retaining wall that could be reasonably expected to pose a hazard to workers unless:
■ The employer provides a support system, such as underpinning;
■ The excavation is in stable rock; or
■ A registered professional engineer determines that the structure is far enough away from the excavation that it would not be affected by the excavation activity or that the excavation work will not pose a hazard to workers. Excavations that would undermine sidewalks, pavement, and appurtenant structures are prohibited unless the employer provides an appropriately designed support system or another effective method of protecting workers from the possible collapse of those structures.

The Excavation standards require employers to take certain steps to protect workers when installing and removing support systems. For example:
■ Members of support systems must be securely connected to prevent sliding, falling, kickouts or predictable failure.
■ Support systems must be installed and removed in a manner that protects workers from cave-ins and structural collapses and from being struck by members of the support system.
■ Members of support systems must not be overloaded.
■ Before temporary removal of individual members, additional precautions are required, such as installing other structural members to carry loads imposed on the support system.
■ Removal must begin at, and progress from, the bottom of the excavation.
■ Backfilling must progress together with the removal of support systems from excavations.

In addition, the standards permit excavation of 2 feet (0.61 meters) or less below the bottom of the members of a support system, but only if the system is designed to resist the forces calculated for the full depth of the trench and there are no indications, while the trench is open, of a possible loss of soil from behind or below the bottom of the support system. Employers must coordinate the installation of support systems with the excavation work.

Employers are responsible for maintaining materials and equipment used for protective systems. Defective and damaged materials and equipment can cause protective systems to fail and lead to other excavation hazards.

Employers must ensure that:
■ Materials and equipment are free from damage or defects that might impair their proper function;
■ Manufactured materials and equipment are used and maintained consistent with the manufacturer’s recommendations and are used so as to prevent worker exposure to hazards;
■ A competent person examines any damaged materials or equipment to evaluate its suitability for continued use; and
■ If a competent person cannot assure that damaged material or equipment can support the intended loads or is otherwise suitable for use, the materials and equipment are removed from service until evaluated and approved by a registered professional engineer.

In addition to cave-ins and related hazards, workers involved in excavation work are exposed to hazards involving falling loads and mobile equipment. To protect workers from these hazards, OSHA requires employers to take certain precautions. For example, employers must:
■ Protect workers from excavated or other materials or equipment that could pose a hazard by falling or rolling inside the excavation by placing and keeping such materials or equipment at least 2 feet (0.61 meters) from the edge and/or by using a retaining device to keep the materials or equipment from falling or rolling into the excavation.
■ Provide a warning system (such as barricades, hand or mechanical signals, or stop logs) when mobile equipment is operated adjacent to an excavation, or when such equipment must approach the edge of an excavation, and the operator does not have a clear and direct view of the edge.
■ Protect workers from loose rock or soil that could fall or roll from an excavation face by scaling to remove loose material, installing protective barricades at appropriate intervals, or using other equivalent forms of protection.
■ Institute and enforce work rules prohibiting workers from working on faces of sloped or benched excavations at levels above other workers unless the workers at the lower levels are adequately protected from the hazards of falling, rolling, or sliding material or equipment.
■ Institute and enforce work rules prohibiting workers from standing or working under loads being handled by lifting or digging equipment.
■ Require workers to stand away from vehicles being loaded or unloaded to protect them from being struck by any spillage or falling materials. (Operators may remain inside the cab of a vehicle being loaded or unloaded if the vehicle is equipped, in accord with 29 CFR 1926.601(b)(6), to provide adequate protection for the operator.)

Water in an excavation can undermine the sides of the excavation and make it more difficult for workers to get out of the excavation. The OSHA standards prohibit employers from allowing workers to enter an excavation where water has accumulated or is accumulating unless adequate precautions are taken to protect workers. Such precautions can include special Trenching and Excavation Safety support or shield systems to prevent cave-ins, water removal to control the water level, or the use of a safety harness and lifeline.

If an employer uses water removal equipment to control or prevent water accumulation, the equipment and operations must be monitored by a competent person to ensure proper use. If excavation work interrupts the natural drainage of surface water, the OSHA standards also require the use of diversion ditches, dikes, or other suitable means to prevent surface water from entering the excavation and to provide adequate drainage of the adjacent area. In addition, a competent person must inspect excavations subject to runoffs from heavy rains, and excavations subject to such runoffs are subject to the requirements described previously in this paragraph.

Atmospheric testing is required before workers enter an excavation greater than 4 feet (1.22 meters) in depth where an oxygen deficiency or a hazardous atmosphere is present or could reasonably be expected, such as in excavations in landfill areas or excavations in areas where hazardous substances are stored nearby. If there are any hazardous conditions present, the employer must ensure that adequate precautions are taken to prevent employee exposure to those conditions. Such precautions include providing workers with proper respiratory protection or ventilation. In addition, when controls are used to reduce the level of atmospheric contaminants to acceptable levels, testing must be conducted as often as necessary to ensure that the atmosphere remains safe.

If hazardous atmospheric conditions exist or may reasonably be expected to develop in an excavation, the employer must ensure the ready availability of emergency rescue equipment, such as breathing apparatus, a safety harness and line, or a basket stretcher. This equipment must be attended when in use.

OSHA requires employers to provide ladders, steps, ramps, or other safe means of egress for workers working in trench excavations 4 feet (1.22 meters) or deeper. The means of egress must be located so as not to require workers to travel more than 25 feet (7.62 meters) laterally within the trench. Any structural ramps used solely for worker access or egress must be designed by a competent person. Structural ramps used for access or egress of equipment must be designed by a competent person qualified in structural design. Also, structural members used for ramps or runways must be uniform in thickness and joined in a manner to prevent tripping or displacement.

Employers must ensure that any worker who enters a bellbottom pier hole or similar deep and confined footing excavation wears a harness with a lifeline. The lifeline must be attached securely to the harness and must be separate from any line used to handle materials. Also, the lifeline must be individually attended by an observer at all times when the worker wearing the lifeline is in the excavation.

Employers must ensure that a competent person inspects all excavations, adjacent areas, and protective systems daily for possible cave-ins, indications of failures in protective systems and equipment, hazardous atmospheres, and other hazardous Trenching and Excavation Safety conditions. Inspections must be done prior to the start of work and as needed throughout the shift. Inspections are also required after natural events, such as rainstorms, or other hazard-increasing occurrences, such as blasting work. If an inspector finds any unsafe conditions during an inspection, the employer must clear workers from the hazardous area until the necessary safety precautions have been taken.

When employers share the details of their safety and health programs with workers, they should emphasize the critical role workers play in keeping the jobsite safe. Employers also need to emphasize specific practices that will help reduce the risk of on-the-job injuries at excavation sites. Such practices can include the following:
■ Know where underground utilities are located before digging.
■ Keep excavated soil (spoils) and other materials at least 2 feet (0.61 meters) from trench edges.
■ Keep heavy equipment away from trench edges.
■ Identify any equipment or activities that could affect trench stability.
■ Test for atmospheric hazards such as low oxygen, hazardous fumes, and toxic gases when workers are more than 4 feet deep.
■ Inspect trenches at the start of each shift.
■ Inspect trenches following a rainstorm or other water intrusion.
■ Inspect trenches after any occurrence that could have changed conditions in the trench.
■ Do not work under suspended or raised loads and materials.
■ Ensure that personnel wear high-visibility or other suitable clothing when exposed to vehicular traffic.

Employers should consider establishing and maintaining safety and health management systems that provide systematic policies, procedures, and practices for protecting workers from job-related safety and health hazards.

The primary hazard of trenching and excavation work is employee injury from a cave-in. Before workers enter a trench, a soil analysis should generally be conducted to determine the appropriate employee protection methods such as sloping, benching, shoring or shielding. Employers should also consider potential struck-by hazards associated with heavy equipment, falling loads, and public vehicular traffic in close proximity to the excavation operations. Also consider potential hazards from undermining sidewalks and buildings. Other unsafe conditions that may be encountered include hazardous atmospheres and electrical hazards from overhead and underground power lines. These five key trench safety tips will help keep workers safe:

■ Ensure that there is a safe way to enter and exit: To prevent injuries during normal entry and exit of a trench or excavation at a job site, employers must provide ladders, stairways, ramps, or other safe means of egress. In some circumstances, when conditions in a trench or excavation become hazardous, survival may depend on how quickly workers can climb out.
• Provide stairways, ladders, ramps, or other safe means of egress in all trenches that are 4 feet deep or more.
• Position the means of egress within 25 lateral feet of workers.
• Ensure means of entering and exiting the trench is within the protective system.
• Structural ramps that are used for access or egress from excavations must be designed by a competent person.
• When two or more components form a ramp or runway, they must be connected to prevent displacement, and be of uniform thickness.
• Cleats or other means of connecting runway components must be attached in a way that would not cause tripping (e.g., attached to the bottom of the structure).
• Structural ramps used in place of steps must have a non-slip surface.
• Use earthen ramps as a means of egress only if a worker can walk them in an upright position, and only if they have been evaluated by a competent person.

■ Ensure trenches have cave-in protection: All excavations are hazardous because soil can be unstable. If workers are not using protective systems or equipment while working in trenches or excavations that are five feet or greater in depth, they are in danger of being crushed by a cave-in. Pre-job planning is vital to incident-free excavation work; safety cannot be compromised as work progresses. The following concerns must be addressed by a competent person:
• Evaluate soil conditions and select appropriate protective systems.
• Construct protective systems in accordance with the standard requirements.
• Plan ahead; contact utilities (gas, electric, water and sewage) to locate underground lines, plan for traffic control if necessary, be prepared to support utilities (pipes/ducts) passing through excavations when necessary, and determine proximity to structures that could affect choice of protective system.
• Test for hazardous atmospheres such as low oxygen, hazardous fumes, and toxic gases, especially when gasoline engine-driven equipment is running, or when the soil has been contaminated by leaking lines or storage tanks. When necessary, ensure that there is adequate ventilation or respiratory protection.
• Provide appropriate protections if water accumulation is a problem (i.e., remove water, divert water flow).
• Maintain safe access into and out of the excavation.
• Inspect the excavation, adjacent areas, and protective systems daily at the start of the shift, after a rainstorm or after any other hazard increasing event. The inspection shall be conducted by a competent person, who looks for evidence of a situation that could result in a possible cave-in, indication of failure of the protective system, hazardous atmospheres or other hazardous conditions.
• Keep excavations open only for the minimum amount of time needed to complete operations.

■ Look for standing water and test for atmospheric hazards: Excavations may present risks of hazardous atmosphere and water accumulation. If any of these conditions exist, workers could be exposed to the possibility of suffocating, inhaling toxic materials, being burned or engulfed by fire, or drowning.

Employers can ensure that excavations are safe to work in by directing the competent persons to inspect excavations:
• Before construction begins.
• Daily before each shift.
• As needed throughout the shift.
• Following rainstorms or other hazard-increasing events (such as a vehicle or other equipment approaching the edge of an excavation). Plan ahead; contact utilities (gas, electric, water and sewage) to identify the location of underground lines and determine proximity to structures that could enter the excavation. Test for hazardous atmospheres where hazardous atmospheric conditions are likely to occur, such as when equipment is running or work is being conducted that could generate a hazardous atmosphere. Examples: low oxygen, hazardous vapors and toxic gases, especially when gasoline engine-driven equipment is running (e.g. when pumping water accumulation from the bottom of the trench), or the soil has been contaminated by leaking fuel lines or storage tanks. When necessary, ensure that there is adequate ventilation or respiratory protection. Provide appropriate protections if water accumulation is a problem (i.e., remove water, use PPE, divert water flow).

■ Keep materials away from the edge of the trench: Excavated material (spoils) at your site are hazardous if they are set too close to the edge of a trench/excavation. The weight of the spoils can cause a cave-in, or spoils and equipment can roll back on top of workers, causing serious injuries or death. Provide protection by one or more of the following:
• Set spoils and equipment at least two feet back from an adequately protected excavation.
• Use retaining devices, such as a trench box that will extend above the top of the trench to prevent equipment and spoils from falling back into the excavation.
• Where the site does not permit a two-foot setback, spoils may need to be temporarily hauled to another location.

■ Never enter a trench unless it has been properly inspected by a competent person: The conditions of an excavation can change during the course of work. Even a properly protected excavation or trench can become compromised. Inspections must be conducted by a competent person. OSHA defines a “competent person” as “one who is capable of identifying existing and predictable hazards in the surroundings, or working conditions which are unsanitary, hazardous, or dangerous to employees, and who has authorization to take prompt corrective measures to eliminate them.”

A "competent person" has training in the use of protective systems, is knowledgeable about OSHA requirements, and has authority to immediately evacuate workers from the excavation and ensure that hazardous conditions are addressed.