Safe Work Procedure: Trenching

Document Number: [SWP-NUMBER] Revision Date: [DATE] Next Review Date: [NEXT REVIEW DATE] Department: [DEPARTMENT NAME]

1. Scope

This Safe Work Procedure (SWP) outlines the safety requirements and procedures for trenching activities to protect workers from cave-ins, falling materials, and other hazards associated with trenching work. It applies to all trenching operations where workers are required to enter a trench that is more than 1.2 meters deep [1].

This SWP covers the steps to be followed before, during, and after trenching operations, including hazard identification, risk assessment, control measures, and emergency procedures.

This SWP should be used in conjunction with other relevant safety procedures and regulations, including those related to excavation, confined spaces, and underground utilities [2].

2. Definitions

Competent Person A person who is capable of identifying existing and predictable hazards in the surroundings, or working conditions which are unsanitary, hazardous, or dangerous to employees, and who has authorization to take prompt corrective measures to eliminate them [2].

Excavation Any man-made cut, cavity, trench, or depression in an earth surface, formed by earth removal [2].

Shoring An assembly of structural members designed to prevent earth or material from falling or sliding into an excavation [3].

Spoil Pile Material excavated from an excavation, trench, tunnel or excavated shaft [3].

Trench A narrow excavation (in relation to its length) 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 not greater than 15 feet (4.6 m) [4].

Temporary Protective Structure A structure or device in an excavation, trench, tunnel or excavated shaft that is designed to provide protection from cave-ins, collapse, sliding or rolling materials, and includes shoring, boxes, trench shields and similar structures [3].

3. Responsibilities

3.1 Supervisors

• Ensure that a competent person inspects the trench daily and documents the inspection [1].
• Ensure that workers are trained and competent to perform trenching tasks [1].
• Provide and maintain all necessary equipment and PPE [1].
• Ensure that all underground utilities are located and marked before excavation begins [5].

3.2 Workers

• Follow all safe work procedures and instructions [6].
• Use required PPE and equipment properly [1].
• Report any hazards or unsafe conditions to the supervisor immediately [1].
• Do not enter any trench that is not properly protected [7].

3.3 Health and Safety Representative

• Assist in the development and review of safe work procedures [1].
• Participate in incident investigations and recommend corrective actions [1].
• Monitor the effectiveness of safety programs and procedures [1].

4. Potential Hazards and Risks

Hazard	Risk	Control Measures
Cave-ins	Injury or death due to entrapment and suffocation	Slope or shore trench walls, use trench boxes or shields [1].
Falling materials	Injury from being struck by falling rocks, soil, or equipment	Keep spoil piles at least 1 meter from the edge of the trench, scale loose materials from trench walls [5].
Underground utilities	Electrocution, explosion, or exposure to hazardous materials	Locate and mark all underground utilities before digging, use hand digging methods near utilities [5].
Hazardous atmosphere	Asphyxiation, poisoning, or explosion	Test for hazardous gases and oxygen deficiency before entering the trench, provide ventilation [8].
Water accumulation	Drowning or collapse of trench walls	Use pumps or other methods to remove water, monitor water levels [8].
Slips, trips, and falls	Injuries ranging from minor to severe	Maintain good housekeeping, ensure proper access and egress [6].
Equipment strike	Injury or death from contact with equipment	Use spotters, establish exclusion zones, ensure equipment operators are trained [9].

5. Personal Protective Equipment (PPE)

Proper PPE must be worn at all times during trenching operations to minimize the risk of injury [1].

• Hard hat - Protects the head from falling objects [1].
• Safety glasses - Protects the eyes from dust, debris, and chemical splashes [1].
• Safety boots - Provides foot protection from punctures, impacts, and crushing hazards [1].
• High-visibility vest - Increases visibility to equipment operators and other workers [1].
• Gloves - Protects hands from cuts, abrasions, and chemical exposure [1].

Inspect all PPE before each use for damage or defects. Replace any damaged or defective PPE immediately [1].

6. Equipment and Tools

Use the right tool for the job and inspect all equipment before use to ensure it is in good working condition [1].

• Excavator/Backhoe - Used for digging and moving large amounts of soil [1].
• Shovels - Used for manual digging and moving soil [1].
• Ladders - Used for safe access and egress from the trench [6].
• Gas detectors - Used to monitor the air quality in the trench for hazardous gases and oxygen levels [8].
• Water pumps - Used to remove water from the trench [8].

Inspect all equipment daily before use. Remove any damaged or defective equipment from service [1].

7. Pre-Job Requirements

7.1 Training and Competency

• All workers involved in trenching operations must be trained in safe work procedures, hazard identification, and the proper use of PPE and equipment [1].
• A competent person must be trained in excavation safety and be able to identify and correct hazards [2].
• Operators of excavation equipment must be trained and certified to operate the equipment safely [1].

7.2 Pre-Job Briefing

• Conduct a pre-job briefing with all workers involved to discuss the scope of work, potential hazards, and control measures [1].
• Review the safe work procedure and ensure that all workers understand their roles and responsibilities [1].
• Discuss emergency procedures and contact information [1].

7.3 Work Area Preparation

• Identify and mark all underground utilities in the area [5].
• Establish a clear work zone and barricade the area to prevent unauthorized access [10].
• Ensure that there is adequate lighting and ventilation in the trench [8].
• Locate all emergency equipment, such as first aid kits and fire extinguishers [8].

8. Safe Work Procedure Steps

Step 1: Excavation

Carefully excavate the trench to the required dimensions, taking care not to damage any underground utilities [5].

• Use appropriate excavation equipment for the job [1].
• Maintain a safe distance from the edge of the trench [5].
• Ensure that spoil piles are located at least 1 meter away from the edge of the trench [5].

Safety considerations: Be aware of the location of underground utilities and avoid damaging them. Ensure that the excavation is stable and does not pose a cave-in hazard [5].

Step 2: Install Protective System

Install a protective system to prevent cave-ins, such as sloping, shoring, or trench boxes [1].

• Ensure that the protective system is appropriate for the soil type and trench depth [1].
• Follow the manufacturer's instructions for installing and using the protective system [1].
• Inspect the protective system regularly for damage or defects [1].

Safety considerations: Never enter a trench that is not properly protected. Ensure that the protective system is installed correctly and is in good working condition [1].

Step 3: Entry and Work in Trench

Enter the trench using a safe means of access, such as a ladder or ramp, and perform the necessary work [6].

• Ensure that the ladder or ramp is securely in place and extends at least 1 meter above the top of the trench [6].
• Wear appropriate PPE, including a hard hat, safety glasses, and safety boots [1].
• Monitor the air quality in the trench for hazardous gases and oxygen levels [8].

Safety considerations: Be aware of the potential for cave-ins, falling materials, and hazardous atmospheres. Follow all safe work procedures and instructions [1].

9. Precautions and Safety Measures

• Competent Person Inspection: A competent person must inspect the trench daily before the start of work and after any event that could affect its stability, such as rain or vibration [1].
• Underground Utilities: Always locate and mark all underground utilities before digging. Use hand digging methods near utilities to avoid damage [5].
• Sloping and Shoring: Slope or shore trench walls to prevent cave-ins. The type of protection required depends on the soil type and trench depth [1].
• Spoil Piles: Keep spoil piles at least 1 meter away from the edge of the trench to prevent materials from falling back into the excavation [5].
• Access and Egress: Provide a safe means of access and egress, such as a ladder or ramp, located within 8 meters of any worker in the trench [6].

10. Emergency Procedures

10.1 General Emergency Response

• In the event of an emergency, immediately evacuate the trench and call for help [1].
• Provide first aid to any injured workers [1].
• Secure the area to prevent further injuries [1].

10.2 Specific Emergency Scenarios

• Cave-in: Evacuate the area and call for emergency services. Do not attempt to rescue anyone without proper training and equipment [1].
• Utility Strike: Evacuate the area and notify the utility company immediately. Do not approach the area until it has been declared safe [5].
• Hazardous Atmosphere: Evacuate the trench and provide ventilation. Do not re-enter the trench until the air quality has been tested and is safe [8].

10.3 Emergency Contact Information

• Emergency Services: 911
• [Company Safety Officer]: [PHONE NUMBER]
• [Project Supervisor]: [PHONE NUMBER]

11. Incident Reporting and Investigation

Report all incidents, near-misses, and hazards to the supervisor immediately [1].

Investigate all incidents to determine the root cause and implement corrective actions to prevent recurrence [1].

12. References and Related Documents

• Occupational Health and Safety Regulations [1]
• Company Safety Policy [1]
• Excavation Safety Standards [1]

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Approved by: [NAME AND POSITION] Date: [APPROVAL DATE]

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