It’s the first day on the job. Your employees are working with an equipment operator to expose some underground sewage lines that a plumber is going to be tying into. The excavator finishes the rough excavation and begins to exit. One of your workers grabs a shovel and prepares to jump into the trench when someone yells, “Stop!”
Just because the operator finished digging the trench, doesn’t mean it’s safe to enter. Every trench is at risk of caving in at any time without warning. Vibrations of nearby traffic or construction equipment, weight of equipment too close to the trench, and the condition of the soil, are just three potential causes.
What your employees need to know
Work in and around the trench should never begin unless an approved cave-in protection method is installed. These include:
- Shoring – timber, mechanical, or hydraulic system structures that supports the sides of a trench.
- Sloping – forming sides of an excavation that are inclined away from the excavation itself. The angle of incline varies with differences in the soil type, environmental conditions, and application of surcharge loads.
- Benching the ground – forming a series of horizontal levels or steps, usually within vertical or near vertical surfaces between levels.
- Trench box – a box placed inside the trench with walls high enough to protect workers if the sides of the trench fail.
What your employees need to do
Each protection method has its own limitations, so workers should never move outside the protected area. Many workers have been injured or killed just because they left the area with the cave-in protection.
Additional steps your workers should follow include:
- Locate the entry/exit points for the trench. Not only are these how workers access and leave the trench under normal circumstances, they are also the escape route should something go wrong.
- Be aware of surroundings at all times and watch for hazards while working in or around trenches.
- Always watch for changes from the day before, e.g. have water, fissures, or any new dirt appeared in the trench? If there are changes from the last time you worked in the trench, exit the trench immediately and inform the “competent person” in charge.
- Never jump over a trench. Always walk around the trench or use approved walkways/bridges.
- Occasionally, trenches can contain hazardous atmospheres such as oxygen deficiency, flammable gases, or atmospheric contaminants. Testing and adequate precautions must be taken to protect against these conditions.
At your safety meeting
A competent person must be on site to conduct inspections prior to entering the trench each day and throughout the shift as needed to identify cave-in potential or any other possible hazards, and to take prompt action if any hazards exist.
Make sure your employees know that they must check with the competent person every time they enter the trench.
Other things to cover at the meeting include:
- Reviewing your site-specific emergency plan, including what to do should someone need to be rescued from a collapsed trench.
- A demonstration and discussion about the protection method you will use and what its limits are.
- Instruction on how to install the protection method.
- Location of entry and exit points.
- Identify any other hazard controls that may be necessary (i.e. air monitoring).
Stress the importance of safety with your employees and remind them frequently why the safety measures are in place. Because the trenching area can be unstable, your employees are at serious risk if you don’t emphasize or they don’t follow safety precautions.
Questions, Comments or Suggestions?
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The above evaluations and/or recommendations are for general guidance only and should not be relied upon for medical advice or legal compliance purposes. They are based solely on the information provided to us and relate only to those conditions specifically discussed. We do not make any warranty, expressed or implied, that your workplace is safe or healthful or that it complies with all laws, regulations or standards.
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