It doesn’t sound very deep, but a 5-foot-deep trench that caves in will cause a fatality. In addition to cave-ins, there are other risks that are posed by trenching and excavation, including falls, equipment accidents, and hazardous atmospheres.
OSHA defines an excavation as “any man-made cut, cavity, trench, or depression in the earth’s surface formed by earth removal. A trench is defined as a narrow underground excavation that is deeper than it is wide, and is no wider than 15 feet (4.5 meters).”
OSHA offers the following guidelines for trench and excavation safety:
- Trenches 5 feet deep or deeper require that a protective system be used. Trenches 20 feet deep or deeper require that a registered engineer design the system, due to the many and complex factors involved. Protective systems include sloping (angling the trench walls away from the excavation), shoring (installing supports to prevent soil movement), and shielding (using trench boxes and similar supports).
- OSHA requires that trenches be inspected daily and monitored for changes in condition by someone who can identify potential hazards.
- All excavations and trenches must provide safe access, such as ladders, steps, and ramps.
- Heavy equipment must be kept away from trench edges.
- Surcharge loads must be kept at least 2 feet (0.6 meters) from trench edges.
- Management and employees should know where underground utilities are located.
- Tests should be done for low oxygen, hazardous fumes and toxic gases.
- Trenches should be inspected at the start of each shift and following rainstorms.
- No one should work under raised loads.
Although OSHA Standards require safety systems in trenches 5 feet or greater, it is imperative that the competent person for trenching evaluates all ground and soil conditions to ensure worker and public safety. In fact, OSHA can cite you for not having a safety system in a trench that is less than 5 feet.
About 15 years ago in the Greenville area, there was a contractor installing water lines that were only about 4 to 4 ½ feet deep. Prior to the accident, we had some deep freezing weather that froze the top layer of soil. On the day of the accident, the weather had warmed up to approximately 60 degrees. The work was being done at the bottom of a low sloped hill. The competent person did not properly evaluate the site and did not identify poor soil conditions. There was a worker inside the trench on his knees fitting pipes together. The earth slid into the trench burring him up to his neck Because of the more shallow trench, coworkers were able to get him out fairly quickly. However, the damage had been done. The worker suffered 2 broken ribs, a punctured lung, a broken left arm and a torn knee.
OSHA cited this company under the General Duty Clause. This clause is used when there is an apparent danger/hazard or an accident resulting from a danger that was not controlled properly. There is no specific standard that addresses this danger/hazard. It is up to the employer to ensure that every employee is working in an environment is free from recognized and potential hazards and that the hazards are properly controlled or employees are protected by PPE or other safety methods.