5 common trenching and excavation safety hazards
A wide range of projects at construction sites require trenching and excavating, but this regular part of the job is a leading hazard for workers. The Occupational Safety and Health Administration, or OSHA, has made reducing hazards in trenching and excavation its priority goal.
Discover OSHA’s digging safety guidelines and how to avoid trenching and excavation safety hazards to keep you and your crew safer on the jobsite.
Trench safety: Preventing the top 5 excavation hazards
Make sure you and your crew take excavation safety hazards seriously. The National Institute for Occupational Safety and Health (NIOSH) reports that more than 80% of trenching fatalities happen in the construction industry. Explore the top five excavation hazards to keep your workers safe and your business running.
1. Trench cave-ins and collapses
Trench collapses remain one of the deadliest excavation hazards. Per the Center for Construction Research and Training (CPWR), OSHA reported that 39 workers died while performing trenching or excavation work in 2022 — more than double the number of fatalities recorded in 2021. More than 80% of trenching fatalities occur in the construction industry, highlighting the importance of proper protective systems and regular safety inspections.
To prevent this serious threat to worker safety, OSHA requires soil composition analysis from a professional engineer or qualified professional. This person will then design and implement a system to prevent worker injury and death. The three steps to avoid collapse hazards include:
Slopes: Ensure trench walls are benched.
Supports: Shore walls to brace them.
Shields: Protect workers from sidewalls with trench boxes.
Bonus tip: Inspect excavations after rain or extreme weather events as well as at the beginning of each shift. Soil stability can shift due to moisture and other weather conditions.
2. Falls into excavations and falling loads
Workers and work equipment or materials falling into trenches represent a safety hazard. If possible, use barriers and signage to mark the area of a fall hazard. Not only construction equipment but also excavated dirt can become a falling load and crush workers.
In order to prevent falling loads, OSHA trench safety standards require jobsites to have materials stored at least two feet away from the edge of an excavation. The agency also recommends not allowing loads to be suspended or raised above workers.
In addition, make sure workers have a safe and secure means of egress in trenches 4 feet deep or more. The competent person who designed the structural ramps must make sure that these don’t create a tripping hazard. Provide trench excavation safety training, so workers appreciate the risks and understand if they’re in unsafe conditions.
3. Hazardous atmosphere in trenches
Not only can excavated areas sometimes have diminished oxygen levels, but a trenched area’s atmosphere can also be contaminated with toxic gases and chemicals. Either or both of these situations can represent a risk for workers.
In excavations deeper than 4 feet, a qualified professional must perform atmospheric testing. Depending on the hazardous atmosphere in the excavation, workers must wear proper respiratory protection equipment to minimize the risk.
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4. Mobile equipment on the construction site
Accidents involving mobile equipment, like dump trucks and backhoe loaders, are another common excavation hazard on construction sites. Mobile equipment operators may have an obstructed view and might not be aware when they’re approaching the trench perimeter.
OSHA suggests minimizing hazards by using a spotter or flagger for vehicles on the jobsite. In addition, require workers to stand back when a construction vehicle is loading or unloading material to prevent them from being hit by flying debris or soil.
Bonus tip: Reduce the risk of working around mobile equipment by making sure you and your crew wear the right protective apparel, including reflective vests. Make sure you also protect your head from construction debris with a hard hat.
5. Hitting utility lines while excavating
Trenching hazards also include electrocution and natural gas leaks from hitting utility lines. To prevent worker fatalities as well as damaged infrastructure, make sure to contact local utility companies prior to excavating.
In many states, digging without calling first is illegal. The easiest digging safety tip is to call your local 811 agency and allow the utility companies the time they require to mark their lines. This will help keep your crew safe and your company from receiving financial penalties.
Frequently asked questions
What’s the difference between trenching and excavating?
A simple way to remember the difference is that all trenches are excavations, but not all excavations are trenches. Specifically, OSHA says an excavation is when soil is removed from the surface of the earth to create “any man-made cut, cavity, trench, or depression.”
A type of narrow excavation, a trench is below the surface of the ground, and its width — measured from the bottom — cannot be greater than 15 feet. Typically, a trench is deeper than it is wide.
OSHA’s requirements for trenches vary and depend on the depth of the trench as well as soil type. Find the excavation safety standards in 29 CFR 1926.650-652, Safety and Health Regulations for Construction.
Who is considered a 'competent' person by OSHA in excavation?
OSHA defines a competent person as someone who has the training and knowledge to recognize existing and predictable dangers — such as cave-in risks, hazardous atmospheres, or water accumulation — and has the authority to stop work until conditions are made safe.
Where is the typical point of failure in an excavation?
The most common point of failure in an excavation is the trench wall or face, especially near the bottom where soil pressure is greatest. When the soil becomes unstable, the wall can shift inward and trigger a collapse. Because cave-ins can happen suddenly and without warning, it's important to use proper protective systems and inspect excavations regularly.
What is shoring in excavation?
Shoring is a protective system that supports the walls of an excavation or trench to help prevent cave-ins. It uses hydraulic, mechanical, or timber supports to hold soil in place when sloping or benching isn't practical. Shoring helps maintain the stability of the excavation and provides an added layer of protection for workers inside.
Under what conditions should you test for air hazards in a trench?
Workers should test for air hazards whenever there's a possibility that a trench could contain a hazardous atmosphere. OSHA requires atmospheric testing before employees enter excavations deeper than 4 feet if there's a risk of oxygen deficiency, toxic gases, or flammable vapors. This can include excavations near landfills, underground storage tanks, sewer lines, or other areas where hazardous substances may be present.
Ferguson can help with excavation safety
To make sure your construction excavation site is in compliance and that you're keeping workers safe, get the safety products and jobsite equipment you need for construction projects of every size from ferguson.com. We have your trench safety needs covered, from hand and head protection to first aid and hearing protection.
While trenching and excavation present unique dangers, maintaining a safe jobsite requires a comprehensive approach. Keeping your team safe from heat-related illnesses is just as crucial as adhering to excavation protocols. For additional vital guidance on protecting your workforce, be sure to read our article on How to Prevent Heat Exhaustion at Work.