Direction Boring and the Hazards to Us!
Ideal Contracting employees were instructed to dig a 30in trench running north to south for the installation of a 6″ irrigation sleeve. The location of the trench was known to be in close proximity to an existing natural gas line that was directionally bored. Ideal Contracting was intending to cross over this line as part of the digging operation. After potholing for the natural gas line, it was determined that the existing natural gas line was 5ft 5in (65in) in depth. This gas line was identified near the building, approximately 20ft away from the location of the strike. The investigation of this incident determined that the area where the trench crossed over the natural gas line, the top of the pipe was only 3’6″ (44in) below grade. The operator was positioned perpendicular to the trench and excavating toward his equipment from the north to the south of the excavation.
When the operator was close to his machine, he began to dig without repositioning. Being in this position caused the bucket to dig lower than 30″ based on the angle he was attempting to excavate at. This operation resulted in the bucket going down 44″ where the gas line’s actual location was.
What is Directional Boring?
Directional boring, commonly called horizontal directional drilling or HDD, is a steerable trenchless method of installing underground pipes, conduits, and cables in a shallow arc along a prescribed bore path by using a surface-launched drilling rig, with minimal impact on the surrounding area. Directional boring is used when trenching or excavating is not practical. It is suitable for a variety of soil conditions and jobs, including road, landscape, and river crossings.
Problems we Encounter With Directional Boring
Directional Boring can result in frequent changes in depth along the line. Blue Staking or flagging is not present in the soil. There are no signs to indicate past excavations have taken place in the area, such as previously disturbed soils, soil coloration, or indicator tape. All the warning signs that we are normally looking for are not present.
How to Avoid Striking a Directional Bore Line
Pre-planning your work is the best way to avoid striking underground utilities. Verify on drawings the location of utilities that could be impacted by your work. Use GPR services and Electromagnetic Toning devices to verify depth. Use soft digging methods to expose lines that could pose a hazard. Never assume you know the depth of the line. Always include your safety department when digging operations are going to be conducted near underground utilities so we can help ensure your safety and the safety of those in your area.
What to do if you hit a utility:
- Call emergency personnel if needed
- Check the safety of employees and the public
- Make sure the proper utility company is notified
- Document everything with notes and pictures
- Supply all information to whoever is fixing the utility and try to help as needed