Understanding Trench Trigger Numbers:
Key Safety Guidelines for Trenching and Excavation
October 28, 2023
Trenching and excavation are essential yet hazardous activities in construction and infrastructure development. To ensure safe practices and compliance with safety regulations, workers must be aware of specific “trigger numbers.” These numbers represent thresholds in trenching guidelines that, when reached or exceeded, require specific safety measures to protect workers from accidents, cave-ins, and hazardous conditions. Here’s a breakdown of critical trench trigger numbers and their significance in the field.
Important Trigger Numbers
- 6 Inches: The maximum distance allowed between a trench box and the trench face, reducing the risk of soil collapse.
- 2 Feet: Keep excavated materials and equipment at least two feet from the trench edge to avoid hazards from falling materials.
- 4 Feet: For trenches four feet deep or more, a safe egress method (ladder, ramp, or stairway) must be available within 25 feet of lateral travel. Atmosphere testing for hazards is also required at this depth.
- 5 Feet: Trenches five feet deep or more require an excavation permit and a protective system against cave-ins.
- 20 Feet: Protective systems for excavations over 20 feet deep must be designed by a registered professional engineer.
Staying Compliant and Safe with Trench Trigger Numbers
Knowing and adhering to these trench trigger numbers is critical to creating a safe work environment for trenching and excavation teams. By following these guidelines, organizations can prevent accidents, stay compliant with regulations, and protect their workforce.
For more information on trenching and excavation safety, consult Reliance Safety Consultants or explore additional resources to keep your team informed and safe.
Additional Tips & Resources for Trench Safety
Daily Inspections: A competent person should inspect trenches daily, especially after weather changes.
Soil Types and Support: Know soil types (Stable Rock, Types A, B, C) to choose the right protective systems.
Sloping and Benching: Use these methods in unstable soils to prevent collapses.
Emergency Plans: Establish a rescue plan and conduct regular drills.
Ladder Placement: Secure ladders in trenches 4+ feet deep, accessible within 25 feet of workers.
Air Quality: Test for hazardous gases and oxygen deficiency in deeper trenches.
Prevent Water Accumulation: Use pumps or barriers to keep water out.
Guardrails for Walkways: Ensure walkways over trenches deeper than 6 feet have guardrails.
Vigilance and Communication: Watch for instability signs and maintain open communication.
Ongoing Training: Keep up with safety practices and take refresher courses regularly.
Check out our online course!
Remember to check out our online trench/excavation safety course available in our LMS. This course provides comprehensive safety guidelines and best practices to keep your team compliant and informed. Contact Reliance Safety Consultants for more details!
For more information on trenching and excavation safety, consult Reliance Safety Consultants or explore additional resources to keep your team informed and safe.