In an overall environment of physical danger where there is little margin for error, the specter of trench cave-ins looms particularly large. Federal reports show that working near unstable ground or in trenches, excavations, or other confined spaces that aren't properly shored up may invite disaster. In one case, a 35-year-old man working in an unreinforced trench died when the walls of a manhole he was building in Medway, Massachusetts, collapsed in on him, burying him alive. In another case, a 68-year-old man was killed in Germantown, Pennsylvania, when the unshored walls of a 16-by-4-foot ditch fell in, covering him with hundreds of pounds of dirt.
To prevent such disasters, the Occupational Safety and Health Administration (OSHA) requires that trenches be inspected daily and as conditions change by a competent person prior to the entry of workers. OSHA also offers these safety tips:
- Use a shield or trench box system designed to protect workers in excavations.
- Assign a supervisor who is familiar with trench safety to oversee the operation.
- Shore the sides of trenches with timber or other materials to make sure that the earth doesn't collapse on workers who have to enter them.
- Slope the sides of trenches on both sides to reduce the weight and pressure exerted by the soil.
- Secure the sides of excavations by engineer-designed sheeting or bracing.
- Protect against falls and water accumulation.
- Provide safe access and exits.
- Have workers wear hard hats and other equipment as needed.
- Communicate with workers about hazards and potential hazards and about access to medical and exposure records.
For more information, see OSHA's safety alert on trenches at http://www.osha.gov/SLTC/trucking_industry/index.html
Occupational Safety and Health Administration. Trench Safety.