A trenching safety plan should include several key elements to protect workers from cave-ins and other hazards. Here's a breakdown of essential components:

1. Pre-Excavation Planning: Before starting any excavation work, it's crucial to identify and mark the estimated locations of underground utility installations such as sewer, telephone, fuel, electric, and water lines [1]. Contact utility companies or owners to establish the exact location of these installations [1]. If they cannot respond within 24 hours, proceed with caution using detection equipment or other acceptable means to locate the utilities [1]. Also, assess the stability of adjacent structures and provide support systems like shoring, bracing, or underpinning if their stability is endangered by the excavation 4, 19.

2. Protective Systems: Implement adequate protective systems to prevent cave-ins. This can include sloping or benching the sides of the excavation, using support systems such as shoring, or installing shield systems like trench boxes [2]. Excavations in stable rock or those less than 5 feet (1.52m) deep may not require a protective system if a competent person determines there is no potential for a cave-in 7, 10.

3. Competent Person Inspections: A competent person must conduct daily inspections of excavations, adjacent areas, and protective systems for any evidence of potential cave-ins, failure of protective systems, hazardous atmospheres, or other hazardous conditions 7, 16. Inspections should occur before the start of work and as needed throughout the shift, especially after rainstorms or other hazard-increasing events 7, 16. If any hazardous conditions are found, employees must be removed from the area until the necessary precautions are taken 7, 16.

4. Atmospheric Hazards: Test the atmosphere in excavations, especially those in landfill areas or near hazardous substance storage, before employees enter, particularly if the excavation is deeper than 4 feet (1.22 m) [3]. Ensure adequate precautions are in place to prevent exposure to hazardous atmospheres, including providing proper respiratory protection or ventilation 4, 18. Emergency rescue equipment, such as breathing apparatus, safety harnesses, and lifelines, should be readily available where hazardous atmospheric conditions exist or are likely to develop 4, 18.

5. Water Accumulation: Prevent employees from working in excavations with accumulated water unless adequate precautions have been taken 4, 18. These precautions may include special support or shield systems, water removal, or the use of safety harnesses and lifelines 4, 18. If water removal equipment is used, it should be monitored by a competent person to ensure proper operation 4, 18.

6. Access and Egress: Provide a stairway, ladder, ramp, or other safe means of egress in trench excavations that are 4 feet (1.22 m) or more in depth, ensuring no more than 25 feet (7.62 m) of lateral travel is required [3]. Walkways with guardrails should be provided where employees or equipment are required to cross over excavations, especially if the walkway is 6 feet (1.8 m) or more above lower levels 7, 16.

7. Protection from Falling Loads and Equipment: Ensure that employees are not permitted underneath loads handled by lifting or digging equipment [3]. When mobile equipment is operated near an excavation edge, use warning systems such as barricades, hand or mechanical signals, or stop logs [3]. Keep excavated materials and equipment at least 2 feet (.61 m) from the edge of excavations or use retaining devices to prevent them from falling into the excavation 7, 19.

8. Sloping and Benching: If using sloping or benching systems, ensure that the slopes and configurations are selected and constructed in accordance with regulatory requirements 2, 10. Employees should not work on the faces of sloped or benched excavations above other employees unless those at lower levels are adequately protected from falling materials or equipment 2, 17.

9. Shield Systems: Ensure shield systems are not subjected to loads exceeding their design capacity and are installed to restrict lateral movement 2, 17. Protect employees from cave-in hazards when entering or exiting areas protected by shields, and do not allow employees in shields during installation, removal, or vertical movement 2, 17.

10. Shoring Systems: Coordinate the installation of support systems closely with the excavation of trenches 2, 17. Ensure shoring is installed and removed in a manner that protects workers from cave-ins and structural collapses, and that shoring components are securely connected to prevent failure [4].

11. Emergency Procedures: Develop and communicate emergency procedures, including readily available emergency rescue equipment and trained personnel 4, 18. Ensure that a competent worker is stationed on the surface to alert workers in the trench of any potentially unsafe conditions and to provide assistance in an emergency [4].

By incorporating these elements into your trenching safety plan, you can significantly reduce the risk of accidents and ensure a safer working environment.