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The Hazards Associated With Directional Drilling: What To Look For And How To Stay Safe

Horizontal directional drilling has greatly increased the ease of performing underground utility installations by reducing the need for time-consuming, labor-intensive and disruptive trenching. It has also increased the safety of the process for workers involved in utility installations by eliminating potential trench wall collapses and other deadly mishaps. However, as with any process used by builders and others involved in utility work, there are still, quite literally, hidden dangers when performing directional drilling. Much of the danger comes from the equipment itself and potential contact with underground obstructions. Below are some of these hazards and some considerations to keep in mind so workers are kept safe:

Drilling string dangers

Perhaps the most obvious of dangers, but one that still bears emphasizing, is posed by the drilling string itself. The string consists of interconnected pipe sections that move in three directions: rotational, forward, and backward. Each one of these can be a threat to worker safety:

  • Rotational – The twisting forces generated by a boring drilling string can snag clothing and draw workers into the rotating pipe. In addition, torque generated by rotating strings can flip over equipment should the string bind or catch. That is why it is important that equipment be placed on stable ground and firmly anchored to prevent or lessen unpredictable movements.
  • Forward – A forward-moving drilling string can injure workers who aren't expecting the movement. For workers on the back end of the job where the string emerges, this can be particularly hazardous should the drilling head unexpectedly penetrate the soil surface.
  • Backward – The backward motion of the drilling string during the back reaming process can be just as dangerous for workers as forward movements. Workers can be caught and pulled into the excavation by the reamer head as it drives backward into the pilot hole.

Accidental contact with underground obstructions

The most insidious danger associated with horizontal drilling is making accidental contact with existing underground structures. There are a myriad of utilities and pipelines, as well as other man-made and natural obstacles, that can traverse the soil just a few feet beneath the surface:

  • High-voltage electrical cables
  • Residential electrical cables
  • Water lines
  • Telephone lines
  • Natural gas pipelines
  • Petroleum pipelines
  • Sanitary and storm sewer lines
  • Concrete footings and foundations
  • Basements
  • Pilings
  • Stump remnants

An underground collision with many of these obstacles can cause costly damage to equipment and infrastructure, but more significantly, collisions with lines bearing electrical current or flammable substances can cause explosions and death or injury to workers.

Avoiding underground contact is ultimately the responsibility of the entity doing the installation work.  Below are some practical ways to avoid a potentially-fatal collision while drilling:

  • Contact your "one-call" service – In several provinces, you can call a toll-free number or make an electronic request before undertaking a digging project. The "one-call" provider will mark all known utility lines that exist in the area, free of charge to you.
  • Perform potholing – Getting the utilities marked by the "one-call" service is an important first step, but you still need to ascertain the depth of the buried obstruction. Potholing is a safe method for verifying utility cable location and depth; it involves making a vertical hole with the use of soil vacuuming or another safe depth testing technology.
  • Be observant – The use of "one-call" and potholing shouldn't serve as a replacement for good judgment. If you notice visual clues that indicate the possibility of an underground obstruction, then take the time to verify that one does or does not exist.

For example, a depressed area may indicate the presence of a buried culvert or other pipeline. Other clues that a potential underground obstruction may be lurking include the presence of manhole covers, no visible utility poles, wide right-of-ways with no surface obstructions, and transformer boxes. Click here for more information about staying safe while doing directional drilling.