According to OSHA, trenching is a leading jobsite hazard, which causes an average of 54 fatalities each year. The following are OSHA’s common trenching and excavation safety standards to help protect yourself and your crew during excavation work activity.

  • Locate and daylight/pothole buried utilities prior to excavation.
  • Trench excavations that are five feet deep or greater are required to have sloping, benching, shielding (trench box) or shoring unless the excavation is made entirely in stable rock.
  • A competent person* may determine that a protective system isn’t required for trench excavations less than five feet deep.
  • A competent person must inspect the excavation and classify the soil type. The classification is based on the results of at least one visual and one manual analysis.
    • Solid Rock
    • Type A Slope ¾ to 1 (53º)
    • Type B Slope 1 to 1 (45º)
    • Type C Slope 1 ½ to 1 (34º)
  • The atmosphere must be tested before entry in trench excavations four feet in depth or greater before entry if the potential for oxygen deficiency or a hazardous atmosphere exists or could reasonably be expected to exist.
  • A ladder or other means of egress must be accessible within 25 feet of the worker’s activity for excavations four feet in depth or greater.
  • Excavated materials and equipment must be kept a minimum of two feet from the edge of excavations.
  • Excavated material must be sloped to prevent the material from re-entering the excavation.
  • A competent person must inspect excavations, protective systems and the area around the excavation daily prior to the start of work and as needed throughout the shift. They should document the inspections.
  • Employees are not to work in excavations where there is accumulated water or where water is accumulating. A pump(s) must be in place to remove accumulating water.

*A competent person is an individual who is capable of identifying existing and predictable hazards or working conditions that are hazardous, unsanitary or dangerous to workers, soil types and protective systems required, and who is authorized to take prompt corrective measures to eliminate these hazards and conditions.

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Members can download the audio version of this toolbox talk here.


1 Competent PersonAn inspection shall be conducted by the competent person prior to the start of work and as needed throughout the shift.
2 DaysContact utilities two days before excavation.
2 FeetSpoils, surcharge or other material or equipment must be set back two feet from the excavation.
2 FeetExcavating no more than two feet below members of support or shield is permitted, if the system is designed for the full depth of the trench, and there is no loss of soil from behind or below the system.
3 FeetLadders must extend not less than three feet above the top of the trench.
4 FeetStairways, ladders or ramps are needed in excavations four feet or more in depth.
4 FeetIn excavations greater than four feet, the atmosphere must be tested if oxygen deficiency or hazardous atmosphere does or is reasonably expected to exist.
5 FeetExcavations less than five feet in depth do not require a protective system if the competent person examines and determines there is no potential for a cave-in.
6 FeetGuardrails are required on walkways that are over excavations six feet or more above lower levels.
18 InchesTrench boxes must extend 18 inches above the top of the vertical sides of the excavation.
19.5 PercentA minimum of 19.5% oxygen must be present before employees can enter an excavation greater than four feet in depth.
20 FeetSloping, benching, or timber and aluminum hydraulic shoring for excavations greater than 20 feet must be designed by a registered professional engineer.
24 HoursSimple slope excavations in Type A soil that are open for 24 hours or less (short-term) and that are 12 feet or less in depth must have a maximum allowable slope one-half horizontal to one vertical.
25 FeetA ladder, ramp or other safe means of egress shall be located in trench excavations that are four feet or more in depth so as to require no more than 25 feet of lateral travel for employees.

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Members can download the audio version of this toolbox talk here.

Trench and Excavation Safety

Originally published 07/12/2017

Trench collapses can occur without warning, regardless of the depth. The vast majority of trenching fatalities occur in trenches 5 to 15 feet deep. But trench cave-ins don’t have to happen. They are preventable with proper planning and execution of safety precautions.

Here are some practices that will help reduce the risk of on-the-job injuries or fatalities on excavation sites.

  1. Know where the underground utilities are located before digging.
  2. Keep excavated soil (spoils) and other materials at least two feet from trench edges.
  3. Keep heavy equipment away from trench edges.
  4. Identify any equipment or activities that could affect trench stability.
  5. Test for atmospheric hazards such as low oxygen, hazardous fumes, and toxic gases when workers are in trenches more than four feet deep.
  6. Inspect trenches at the start of each shift. This should be done by the competent person. The competent person should be authorized to order immediate corrective action, including restricting entry into the excavation, until any hazards or potential hazards have been eliminated.
  7. Ensure that employees working in trenches four feet deep or more have an adequate and safe means of exit, such as ladders, steps or ramps. These must be within 25 feet of all workers at all times and will need to be relocated as the job progresses.
  8. Inspect trenches following a rainstorm or other water intrusion.
  9. Inspect trenches after any occurrence that could have changed conditions in the trench.
  10. Do not work under suspended or raised loads or materials.
  11. Ensure that workers wear high-visibility or other suitable clothing when exposed to vehicular traffic.
  12. Develop a trench emergency action plan and train workers and supervisors on the proper actions to take in case of an emergency.

Remember: Unlike most accidents, the cave-in of an excavation can usually be predicted if closely watched. So stay alert. Don’t take anything for granted.

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The Hazards of Leading Edges – Part II: Excavation

This week we’ll look at leading edge hazards in excavation work. OSHA regulates hazardous elevations starting at 48 inches (four feet) in general industry, and 72 inches (6 feet) in construction. However, proactive safety management programs look for leading edge hazards at any height and create plans to protect workers.

The leading edge of an excavation project poses several potential injury scenarios, including falls and cave-ins. The danger to workers and equipment is great if the edge warning is limited or non-existent. Devastating impact injuries occur from falling into excavation holes, especially if the worker lands on an object, such as a concrete pipe or concrete forms.

Never pile excavated material (spoils) too close to the edge of a trench/excavation. It obscures the view of the edge, which makes it possible for equipment to drive off the edge and into the excavation.

Soil at the leading edge of an excavation site has a low, unconfined compressive strength, meaning the soil does not have anything to push against when it is compressed. An edge with low compressive strength can result in the soil giving way, and anyone or anything at that edge will cascade into the hole.

Provide leading edge protection on an excavation site by doing one or more of the following:

  • Use snow fencing or other visual warning material to create a warning barrier.
  • Set spoils and equipment at least two feet from the excavation.
  • Where the site does not permit a two-foot set back of materials, temporarily haul spoils to another location.

Leading edges exist in all types of construction. Make sure your jobsite safety audit includes an inspection of all leading edges and provides a plan of action for protecting workers.