OSHA Bulletin Provides Information on Horizontal Drilling Hazards
OSHA’s "Avoiding Underground Utilities During Horizontal Directional Drilling Operations" addresses safe operations and specific methods to avoid underground lines and reminds contractors to use the state’s utility location system before any drilling occurs.
What is Horizontal Directional Drilling (HDD)?
HDD is a trenchless technology that uses surface-launched equipment to drill underground horizontally and install pipes, conduit, and cables. Although HDD technology is thought to take less time, require fewer workers, and cause less surface damage compared to traditional open trench excavations, it is more difficult to avoid utility lines due to the limited visibility inherent to the process.
Potential hazards associated with HDD include mechanical rotating parts, high-pressure drilling fluid, and damaging electric and gas lines, which can lead to electrocution, fires, and explosions.
To ensure safety, OSHA recommends:
- Use site-specific safety assessments to determine appropriate drilling techniques and safety practices
- Develop a fire protection program and follow it throughout all construction phases
- Contact the local utility location services to mark lines and assist with determining utility locations
- Compare drawings with surface markings, as some utility lines may miss detection or may be missing from utility maps
- Review drawings and contact utility companies directly, whenever possible, to verify underground utility locations
- Ensure that the HDD machine operator and tracker walk through the planned drill path during planning and site preparation. Check for structures like gas meters and manhole covers that may indicate an underground utility line, obstructions along the drill path, and potential sources of interference that could affect tracing device readings
- Use safe and appropriate potholing techniques to the planned drill path’s depth to expose any hidden underground utilities
- Before starting the operation, train HDD machine operators and trackers to communicate effectively with hand signals and radios
- Ensure that trackers check the tracking device readings frequently during HDD operations and compare them with pre-operational walkthrough readings. If any changes in readings occur, the tracker should immediately signal the HDD machine operator to stop drilling, investigate, and take appropriate safety precautions before continuing to drill.
- Instruct trackers to look into the potholes to observe the drill stem as it passes near the underground utility lines during drilling, and guide the HDD machine operator along the bore path to avoid striking a line.
- Instruct trackers to observe the back reamer to verify that it follows the bore path and avoids utility lines
- Drill at a pace that is slow enough to permit the tracking device to sense any drill line deflections caused by large obstructions