OSHA is well aware of just how many injuries, both fatal and non-fatal, are associated with excavation/trenching. In fact, the Agency has been conducting a trenching initiative for the past several years. In an effort to lessen the number of excavation/trenching-related fatalities, OSHA designated a trench initiative team in 2003 to identify safety issues and to develop outreach materials. Although the Agency’s studies have shown that there has been a steady decline in fatalities, it is still continuing its outreach efforts to remind employers of the need for constant attention to prevent cave-in fatalities.
The trench task force enumerated a number of possible risks that employees might encounter while working in an excavation. However, there are five risks that are most often cited by OSHA inspectors when they examine a site:
1. Lack of adequate protective systems – OSHA Standard 1926.652(a)(1) requires that any excavation between 5 feet and 20 feet deep must have protective systems to prevent a cave-in. The acceptable forms of protective systems include:
- Shoring – These are timber, mechanical, or hydraulic systems that support the sides of an excavation.
- Sheeting – A system in which plates or shoring-grade plywood are driven into the ground to keep the earth in position.
- Shielding (also known as a trench box) – This protects the workers in the event of a cave-in. The box is placed in the trench and moved with the employees as the work in the trench progresses.
- Sloping – A method of cutting back trench walls at a steep enough angle so that a cave-in isn’t possible. The angle depends on the type of soil.
- Benching – This technique cuts into the sides of an excavation to form one or more horizontal steps.
2. Failure to make necessary on-site inspections – A competent person on-site must inspect the excavation, the surrounding areas, and all protective systems on a daily basis for indications that a cave-in might occur, protective systems might fail, or that other hazardous conditions are present. Inspections should be conducted prior to the start of workday and before the beginning of each shift. Inspections must also be made after an event that might increase the possibility of a cave-in, such as a rainstorm.
3. No adequate method of access and egress – Excavations/trenches that are 4 feet deep or more must have proper means of egress. OSHA has established the following guidelines:
- The means of egress must be positioned within 25 lateral feet of workers.
- A competent person must design structural ramps that are used solely for access or egress from excavations.
- When two or more components form a ramp or runway, they must be effectively connected to prevent displacement, and be of uniform thickness.
- Cleats or other means of connecting runway components must be attached in a way that would not cause tripping.
- Structural ramps used in place of steps must have a non-slip surface.
- Earthen ramps cannot be used as a means of egress unless a worker can walk them in an upright position, and a competent person has evaluated them.
4. Improper placement of spoil piles – These must be placed at least 2 feet back from the excavation to prevent debris falling into the site.
5. Failure to quickly evacuate at-risk employees – As soon as the competent person discovers an indication that a cave-in might occur, a protective system could fail, or that other hazardous conditions are present, exposed employees must be removed from the excavation until the necessary measures have been taken to make working in the area safe again.