Federal agencies Utilities Injury prevention

Safety bulletin focuses on horizontal directional drilling hazards

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Washington — OSHA has published a Safety and Health Information Bulletin intended to help underground utility workers and employers avoid hazards associated with horizontal directional drilling.

Workers performing HDD face reduced visibility compared to those involved with vertical drilling, the bulletin states. Installing underground utility lines safely via HDD equipment helps keep drills from contacting or rupturing existing underground lines for electric, water, sewage, gas, steam and chemical utilities. Hitting and breaking underground electrical or gas wires, however, puts workers at risk of electrocution, gas leaks and explosion.

In 2013, an HDD operation in Kansas City, MO, damaged a natural gas line – triggering an explosion and fire at a nearby restaurant. One restaurant worker was killed, and three HDD workers were severely injured.

The bulletin includes tips to help workers avoid making contact with lines:

  • Perform a visual inspection of the planned digging path. If possible, physically confirm underground locations by digging small test holes from the surface, also known as potholing.
  • When possible, review drawings and contact utility companies directly to review underground utility locations.
  • Analyze findings with surface markings to determine any missed utilities.
  • Call 811 before digging to ensure no utility lines are in the work area.

Although HDD operations are considered trenchless, OSHA wants workers to be aware of trenching and excavation controls for projects in which trenches are used to accommodate the machine or reception pit.

The agency recommends that employers provide job-specific training for workers to identify utility lines; use potholing; and follow proper protocol to identify, evacuate and report natural gas leaks. Signs of a natural gas leak include dirt, water or debris blowing from the ground to the air; an unusual hissing, whistling or roaring sound near a natural gas line; and a distinctive sulfur-like odor.

In addition, because some gases are odorless, OSHA recommends the use of handheld natural gas detectors.

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