HDD Project Completed In Cascade Mountains

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

“That we would attempt these bores with this equipment probably raised some eyebrows,” said Lachner. “I’m sure there were those who didn’t believe it could to do the job in these conditions. However, we are confident in our capabilities. We like difficult projects, but we don’t undertake anything we aren’t confident in completing. Although we’re a young company, our management and personnel have many years experience in HDD, including many difficult projects, and we’ve already established a reputation for doing jobs other contractors don’t want to take on. We have experience with the mechanical drive system on smaller machines and were comfortable the 100,000-pound model could do the job.”

The Ditch Witch JT100’s All Terrain (AT) dual-pipe mechanical drilling system -- Lachner calls it a mechanical mud motor -- employs an inner rod to drive a rock bit, and the outer pipe uses a bent sub to steer the downhole tool for drilling pilot holes and provides rotary torque for the hole opener during backreaming. It is designed to delivery maximum downhole horsepower to the bit while operating with low volumes of drilling fluid.

Apex handled the job as a design/build project, performing a turnkey operation that included detailed planning of the bores and completion of each HDD installation.

“Planning each bore was critical,” said Lachner. “With the severe downward angles, it was essential to level off at exactly the correct point and then start up the opposite slope at exactly the right spot to hit the projected exit point. Profiles were critical, and we had to maintain a 40-to-45-foot depth because our plan was to use walk-over tracking equipment and if we went deeper, we could lose tracker signal.”

Apex’s JT100 unit had been doing long-haul work on the east coast, and was brought to Washington for the mountain project. A five-man crew began work in October 2010.

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Logistical nightmare
The logistics of getting the drill unit, support equipment, supplies and personnel to set-up locations was complicated and difficult.

“Some roads had to be built, and launch pads constructed and maintained,” said Lachner. “Equipment was hauled over mountain roads with a D8 Caterpillar dozer. On some of the bores, it was seven miles from a paved road to the set-up location. The two-inch duct was on reels, and the D8 Cat pulled reel trailers to work sites. Crew members and supplies were brought in and out with a 6x6 ATV.”

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