Trenches that are what depth or greater require a protective system designed by a Professional Engineer?

• A. 15 feet
• B. 20 feet
• C. 10 feet
• D. 25 feet

Answer: (B)

Trenches that are 20 feet in depth or greater require a protective system designed by a Professional Engineer to ensure safety during excavation activities. This requirement is aligned with regulations and safety standards aimed at preventing cave-ins, which are among the most hazardous events occurring in excavation work. The designation of 20 feet is significant because it marks a threshold where the risks increase substantially, necessitating advanced design and engineering intervention to provide adequate safety measures for workers in those trenches.

In contrast, trenches that are shallower than this depth may be managed with simpler protective systems, such as sloping or benching, which can be designed and implemented by competent persons rather than needing specialized engineering plans. Thus, the 20-foot depth is a critical standard in occupational safety for trenching operations.