A recent incident highlighted the critical importance of establishing and following strict procedures when carrying out excavations. A groundworks team accidentally struck a gas main while working on-site, fortunately resulting in no serious injuries. However, the release of gas did cause short-term health issues for some operatives and nearby residents. This event underscores the potential dangers associated with underground service strikes and the need for robust preventative measures.
Understanding the Risks
Underground services pose significant risks during excavation work, with the potential to cause severe injury or damage if struck. Here are some key hazards associated with common underground services:
- Electrical Services: Typically buried at depths of 450mm to 1m, these services can cause explosions or fires if damaged, leading to serious injuries or fatalities due to arcing.
- Gas Lines: Found at depths ranging from 375mm to 900mm, gas lines can result in explosions or fires if breached. A leak may not be immediately apparent, making it a delayed and hidden danger.
- Water Pipes: Located between 750mm to 900mm deep, high-pressure water lines can cause flooding, potentially leading to drowning or collapse of excavation sides due to instability.
- Telecoms: These services, which vary in depth, may not pose direct physical danger but can cause significant disruption and incur high repair costs if damaged.
It’s essential to recognize that these services might not always be at the expected depths, and a strike to one service can lead to collateral damage to others.
Implementing Safe Practices
To mitigate these risks, it is crucial to implement comprehensive safety procedures. The key elements include:
- Planning: Before commencing any work, obtain accurate service drawings and other relevant information from the client. Use these details to plan the excavation process carefully, ensuring minimal risk to existing services.
- Detection and Marking: Utilize multiple methods to detect and identify underground services. Utility plans, while helpful, may not always be accurate, especially on private land. Supplement these plans with visual inspections, looking for indicators like lamp posts, gas service pipes, or evidence of previous trenching.
- Tools for Detection: Use a Cable Avoidance Tool (CAT) and a signal generator (Genny) to detect underground services. However, these tools have limitations, particularly in areas with multiple services or where non-metallic pipes are involved. Proper usage is essential for accurate detection.
- Marking: Once services are identified, clearly mark their locations on the ground using paint, ensuring that all team members are aware of their positions.
- Safe Digging Practices: Even with thorough planning and detection, it is impossible to guarantee the absence of underground services. Therefore, always adopt safe digging practices:
- Avoid using power tools or excavators within 500mm of identified services.
- When exposing buried services, follow a specific process, such as using hand tools or vacuum excavation, to minimize the risk of damage.
- Employ a banksman to oversee the excavation process. The banksman should focus on monitoring the ground for any signs of buried services and maintain clear communication with the excavator operator.
Conclusion
The recent incident serves as a powerful reminder of the importance of stringent safety measures when working near underground services. By implementing these procedures—thorough planning, accurate detection, and safe digging practices—we can significantly reduce the risk of service strikes, ensuring the safety of our teams and the surrounding community. Always prioritize safety and remain vigilant during excavation work to prevent potentially catastrophic incidents.
