All accidents and deaths pertaining to trenching and excavating are preventable. Some of the contributing factors are:
Inadequate hazard assessment
Improperly sloped walls
Incorrect shoring materials
When to Add Protection
Under no circumstances should you enter a trench and/or excavation deeper than 1.5 metres (5 feet) unless it is properly sloped or shored.
Equip Yourself with Knowledge
With underground facilities, the smallest incident can cause incredible destruction. You can prevent disasters by following these basic steps:
Plan your work
Call before you dig
Hand expose facilities
Both excavators and owners of buried facilities are responsible for preventing damage to underground facilities. Make sure you do your part.
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What Can Happen to You
If you are in an unsafe trench or excavation you could suffernot only yourself but endure hardships amongst family and friends:
And possible death due to suffocation (soil weight)
Are you will to take this risk?
Some Common Hazards with Trenching & Excavating
Underground and overhead facilities
Collection or seepage of water
Use of inadequate materials
Failure to install safeguards
Are You Prepared for the Unexpected?
No one can predict a trench or excavation cave-in yet when a cave-in does happen you only have seconds to respond. The development of an emergency response plan for a rescue must be included in the site hazard assessment.
How you secure a trench depends on the soil type. Make sure you know what type it is (Refer to current OHS Legislation):
Hard and compact-soil that can only be excavated by machinery and shows no sign of cracks after excavation.
Likely to crack or crumble-soil that can be excavated with hand tools, shows signs of cracking after excavation, and has a low to medium moisture content.
Soft, sandy, or loose-soil that is easily excavated with hand tools and will run or shift if unsupported.
If an excavation contains soil of more than one type, the employer must operate as if all of it is the soil type with the least stability.
Get a Professional
When designing the construction of a safe trench and/or excavation, nothing can take the place of experience and knowledge. If you have any doubts - get additional help. A small doubt could signal a large catastrophe.
Use the applicable legislation to find the sloping angle for your specific job. For reference, here's a chart for 45-degree angle slopes:
Width of Trench Across Top to Give 45-Degree Cut-Back
Bottom Width 1.2m 1.8m 2.4m
Depth(Metres) Width across the Top (Metres)
2.1 5.4 6.0 6.6
3.1 7.4 8.0 8.6
4.0 9.2 9.8 10.4
4.9 11.0 11.6 12.2
5.8 12.8 13.4 14.0
6.7 14.6 15.2 15.8
7.6 16.4 17.0 17.6
8.5 18.2 18.8 19.4
Read the manufacturer's specifications to find out proper installation procedures and how the shoring is designed to be used. Each type of shoring can be different:
Other methods designed by engineers
Remember - always stay in the protected area of the trench. Even one step out is too far.
Changing conditions and time itself can make a previously safe trench hazardous. Keep a constant eye on the condition of the trench and the equipment you are using.
It's Not Child's Play
Watching children at play in a sandbox will give you an understanding of their fascination with moving earth and heavy equipment. Unfortunately, sometimes children don't know to stay away from the real thing.
Talk to your children about the dangers of heavy equipment and trenches. Explain that the workers who work in trenches have special equipment and knowledge so they can be safe. Children can easily get hurt in these areas.
Sometimes, adults don't know when to stop either. If you need to do any work to your house or cottage that requires you to dig a trench (such as sewer lines) you may be getting in over your head.
Use Professionals-they will do a safer and better job.
Think About Others
Trenches can be completely safe if you use proper equipment, follow legislation, and use safe work procedures. Make sure you and your co-workers work as a team - protecting yourselves and each other. You also need to make sure other people cannot be injured in trenches. Never leave an unprotected trench open. Use barricading, fencing, or even backfill it. You may save the life of a child.
For more information, refer to current applicable Occupational Health and Safety Legislation.