Construction trenching accidents result in 40 fatalities and numerous injuries each year. The American Society of Safety Engineers (ASSE) recognizes that many of these fatalities can be prevented by using government and industry safety standards.
A construction trench is a narrow excavation made below the surface of the ground. In general, the depth is greater than the width, but the width of a trench (measured at the bottom) is usually not greater than 15 ft. (4.5 m).
A trench is a space where cave-ins, falls, falling objects and bad air can cause worker fatalities. Also, electrocutions or explosions can occur when workers contact underground utilities and bad air in small spaces can damage a worker’s breathing, contribute to causing a fire, or poison the worker.
The U.S. Occupational Safety and Health Administration’s (OSHA) trench standard is in the Code of Federal Regulations: 29 CFR 1926.650, 651 and 652. OSHA requires that workers in trenches and excavations be protected. The standard addresses a variety of hazards such as evaluating soil conditions, selecting protective systems, contacting and communicating with utility companies to locate underground lines, planning for traffic control, and determining proximity to structures that could affect choice of protective systems.
“Key issues that should be addressed when involved in an excavation project include people working in vertical trenches often on short duration projects commonly without trench boxes or adequate shoring; not understanding how dramatically water, vibration and previously disturbed dirt impacts stability; and, the chance of rescuers getting hurt by a secondary cave-in,” ASSE member Mike Hayslip, of Ohio, said.
Hayslip has a professional civil engineering license and also is a member of the ASSE Construction Practice Specialty.
“The information is readily available for employers and employees alike to help ensure a safe excavation project,” Hayslip said.
In addition to the OSHA standard, voluntary national consensus standards published by the American National Standards Institute (ANSI) address excavation and the hazards associated with trenching. These include the A10.12-1995 Standard Safety Requirements for Excavation, and the A10-16-1995 (R-2001) Construction and Demolition Operations — Safety Requirements for Tunnels, Shafts and Caissons.
OSHA and ANSI standards point out how important it is that:
• trenches be inspected by a competent person that understands the OSHA excavation standard before every shift and as new hazardous situations arise;
• all equipment associated with the excavation be checked to see that it is in good condition;
• safe access in and out of the trench is in place;
• a rescue plan is in place, and rescue equipment is at the job site;
• the soil is evaluated to determine the correct worker-protection systems (such as shoring) that must be in place; and
• the spoil piles are kept 2 ft. or more (.6 m or more) from the trench.
Formed in 1911, the non-profit Des Plaines, IL -based American Society of Safety Engineers is the largest and oldest professional safety organization and is committed to protecting people, property and the environment.
ASSE’s more than 30,000 occupational safety, health and environmental professional members manage, supervise, research and consult on safety, health, transportation and environmental issues in all industries, government, labor and education.
For more information, visit www.osha.gov, www.cdc.gov/niosh or www.asse.org.