What is Horizontal Directional Drilling?

Horizontal Directional Drilling (HDD, Directional Boring, directional drilling) is a method of installing underground pipelines and conduits from the surface along a prescribed bore path. The process is successfully used for installing telecommunications & power cable conduits, water lines, sewer lines, gas lines, oil lines, product pipelines and casings used for environmental remediation. Typical crossings include waterways, roadways, congested areas, environmentally sensitive areas and any area where other methods are more expensive or not feasible. Use of HDD is growing rapidly and is expected to continue to increase for the foreseeable future.

Pilot Hole- The first stage consists of drilling a small pilot hole. Drilling fluid is pumped through the drill pipe to the drill bit where high pressure jets and the bit will grind the soils ahead of the drill stem. The drilling fluid will also carry the cuttings back to the entrance pit at the drill rig. Tracking of the pilot hole shall be by means of a walkover guidance system. An electronic transmitter behind the drill head will send a signal to the locator at the surface directly above the drill bit to give the exact coordinates of the drill stem. A reading will be taken every 5 to 15 feet to check the depth, alignment, and percent slope of the drill head. Corrections will be made by the operator and locator to keep the pilot hole along the predetermined bore path. The speed of the pilot hole will vary upon existing soil conditions and the amount of steering which is required. Upon reaching the exit point, the beacon housing and bit is detached and replaced with a reamer.

Pre-Reaming- The second step is to pre-ream the pilot hole and enlarge it to a size sufficient to safely install the lines. A reamer is pulled back and rotated while pumping drilling fluid to cut and remove solids to enlarge the hole. Pre-reaming speeds will vary depending on existing soil conditions and the amount of cuttings that are removed from the hole. Bentonite and additives will be used to ensure a clean and stable hole. Bentonite is used to create a layer around the outside of the hole while pre-reaming. This will help stabilize the bore hole and with fluid loss or infiltration. Additives such as detergent and polymers are used to help break up the clay soils. A more evenly mixed drilling fluid will prevent any blockages inside of the bore hole.

Pipe Pullback- The final step is the pullback of the pipe. The drill rod and reamer will be attached to a swivel, which is utilized between the pipe and the reamer to prevent any torsional stress from the rotating drill being transferred to the pipe. As the pipe is pulled into the hole, drilling fluid is pumped downhole to provide lubrication.

Why Directional Drill instead of Trench?

  • Less traffic disruption
  • Lower cost
  • Deeper installation possible
  • Longer installation possible
  • Faster completion times
  • Directional capabilities
  • Safer for the environment


Contact Info:

Main Phone: 360-673-4433
Fax: 360-673-4466

Jimmy Downing, Estimates

Diana Downing, Operations

Jaimie Hinckle, Office Manager


Email: downingHDD@kalama.com

447 N. First Street Ste 250 - Physical
P.O. Box 33 - Mailing
Kalama, WA 98625


Our Services
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