HDD Project Completed In Cascade Mountains

Extreme Boring
By Jeff Griffin, Senior Editor | May 2011, Vol. 66 No. 5

Directional drilling installations that a dozen years ago would have been considered impossible are routinely performed today. Projects in difficult conditions that made industry news then are commonplace now.

Broader applications of horizontal directional drilling (HDD) is the result of the combination of better equipment and downhole tools, understanding of the use of drilling fluids and the knowledge and experience of the crews who understand how to use these technologies to maximum advantage.

There always will be “can’t-be-done” jobs that will be completed by enterprising drillers, and there’s a small group of HDD specialists who seem to relish tackling such projects.

One of the most difficult and impressive recent HDD projects was completed this winter high in the Cascade Mountains of Washington.

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General contractor Robinson Brothers, Vancouver, WA, was responsible for relocating approximately eight miles of aerial fiber optic cable. It was failing due to the harsh weather and was to be placed underground. HDD segments were subcontracted to Apex Directional Drilling. The cable route went up and down steep, heavily-wooded mountainsides and crossed canyons, some of which contained streams and lakes. Solid and fractured basalt encountered in drilling ranged in hardness from 20,000 to 50,000 psi.

Two, 2-inch diameter HDPE ducts to hold fiber optic cable were placed in the ground. Approximately five miles of the route was plowed, with three miles put in the ground by directional drilling.

“It was clear at the beginning that these would be extremely challenging bores to complete,” said Apex Directional Drilling President Mike Lachner. “This was a high-profile project and it attracted a lot of attention and interest.”

Equipment choice
The Apex bid costs were based on using a 100,000-pound pullback drill unit with a dual-pipe mechanical drilling system, rather than a larger machine with a mud motor. Not employing a mud motor eliminated the need for support equipment required for that technology and greatly reduced the quantities of drilling fluid necessary.

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