Trench and Excavation Hazards

Trench and excavation hazards are higher than general construction. Cave-ins kill two workers every 30 days. Hear how to keep workers safe in your big digs.

In this podcast, Dan Clark describes trenching protective systems, including sloping, benching, shoring and shielding. You’ll also hear tips from safety official and excavation expert Dan Taillefer about the dangers of interrupting utilities, vehicle traffic, weather and more.

Also discussed are OSHA requirements on soil types (A, B and C), means of egress (ladders, stairs or ramps), and regular inspections by a competent person.


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Dan Clark: Let’s say a cubic yard of dirt falls on you. Could you crawl your way out? Doubtful. That amount of dirt can weigh as much as a car. So, be careful in trenches and excavations.

Hi there, I’m Dan Clark of The Safety Brief. This is where we talk about health and safety hazards in today’s demanding industrial and construction worksites, a service of Creative Safety Supply. Save 10% off your entire order at with coupon code SAFETYBRIEF. All one word. SAFETYBRIEF.

Excavation is any type of hole dug in the ground. A trench is a type of excavation, they’re more narrow, usually deeper than they are wide, and have soil on all four sides.

Trench_and_Excavation_Hazards-Creative_Safety_Supply-250x67Dan Taillefer : Excavation work is inherently hazardous ‘cause there’s several hazards that could come up during excavation.

Dan Clark: That’s Dan Taillefer, Occupational Health and Safety Inspector with the Ontario Ministry of Labour

Dan Taillefer : Contact with overhead power lines, disrupting buried utilities and services, cave-in of the excavation wall.

Dan Clark: And excavation changes the pressure in the ground making it uneven causing the soil to collapse into the hole

Dan Taillefer : During a cave-in, the worker can be trapped immediately by the weight of the soil that is collapsed from the trench wall and a worker has no chance in that circumstance.

Dan Clark: Trenching cave-ins kill two workers every month the US. Don’t let an unprotected excavation be an early grave.

Trench_and_Excavation_Hazards-Creative_Safety_Supply-250x167Dan Taillefer : You must identify what kind of soil you’re dealing with so you can apply the proper protective measures such as a trench box, proper shoring or if, as an option, you can slope the excavation walls adequately.

Dan Clark: Unless the excavation is in solid rock, OSHA requires protection against cave-ins for all trenches more than 5 feet deep for any of the soil types—A, B or C—or for any depth that shows the signs of a cave-in.

Trench_and_Excavation_Hazards-Creative_Safety_Supply-250x660SLOPING makes angled sides of the excavation.

BENCHING makes the sides of the excavation in multiple levels, like stairs.

SHORING is placing wood or metal against the sides of the excavation, supported by braces to prevent the soil from collapsing.

SHIELDING creates a space around the workers that protects them in case of a cave-in. A trench box is the item often used to do this, which is lowered into the trench and surrounds the workers.

A competent person must inspect trenches at the start of each shift, and as needed during the workday.

Dan Taillefer : conditions can change at a moment’s notice. It all depends on weather conditions, outside effects such as vibration from traffic, from a nearby roadway, equipment working in the vicinity of the excavation.

Dan Clark: Keep all equipment, materials and spoil piles at least two feet back from trench edges.

Dan Taillefer : And that is to ensure that there’s no extra pressure on the excavation walls.

Dan Clark: OSHA also requires safe entries and exits with ladders, ramps or stairways. They must be within 25 feet of any worker.

And before you start digging, know where the underground utilities are located.

Dan Taillefer : Excavation work is extremely dangerous and it’s extremely important for all parties working at an excavation site to be diligent of the changing conditions and to ensure that proper protective measures are installed at your excavation site.

Dan Clark: Dan Taillefer, Occupational Health and Safety Inspector with the Ontario Ministry of Labour.

And that’s it for this episode on Trench And Excavation Hazards. Come back for more ways to stay safety compliant in today’s ever-changing landscape of safety requirements. I’m Dan Clark of The Safety Brief, a service of Creative Safety Supply. Save 10% off your entire order at with coupon code SAFETYBRIEF. All one word, SAFETYBRIEF.


Additional links:

CDC / NIOSH: Preventing Worker Deaths from Trench Cave-ins

OSHA Fact Sheet: Trench Excavation

OSHA video is below: Excavations In Construction/Trenching


tape measure image: Virginia Department of Labor and Industry

Trenching protective systems image © CIDWT. 2009. Installation of Wastewater Treatment Systems. Consortium of Institutes for Decentralized Wastewater Treatment. Iowa State University, Midwest Plan Service. Ames, IA.

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