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HDD Project Completed In Cascade Mountains
For each pilot hole, 6½ -inch tri-cone bits were used. To keep pilot holes open during product pullback, a 6-inch Rockmaster backreamer was connected in front of the pipe string.
A Ditch Witch 752 walk-over tracking system was used in conjunction with a TMS bore planning system, a Windows-based bore management tool to plan the bore, monitor its real-time progress and print an as-built map of the completed installation.
Throughout the project, weather made working conditions difficult.
“We got started in October 2010,” Lachner said, “and the snows came in November. From then through completion of the last bore in February 2011, we worked in winter conditions. With heavy winds and freezing temperatures, along with significant snowfall we were forced to bring in all-terrain vehicles to mobilize in and out of the drill sites each day. The location furthest out was roughly seven miles from the base of the mountain.”
Keeping equipment from freezing and supplying machines with water and fuel were issues, also.
“We had to carry in diesel fuel in portable slip tanks and gas cans over the course of each day,” Lachner continued. “With water trucks having limited access to our drill sites, we had to schedule each day based on their mobility to us. We ran Cat D9 dozers all day everyday up and down the mountain roads to keep them clear enough to drive on and even at that our 4x4 rigs were not always able to maneuver up and down the steep hills. We transported all our equipment and tooling to and from each drill site on trailers with large excavators and dozers because the access roads, even when clear, were too steep and curves were too sharp for trucks to travel.”
Constant high winds through the mountain canyons made it necessary for continual maintenance on tents and shelters built to cover fluid mixing systems and reclaimers. High-grade propane heaters and large containers of propane were used to keep them warm in the freezing temps. Snowfall at its peak was about six feet with drifts as high as 10-12 feet on both sides of the bore sites.
“At times, we had to move snow to keep equipment from being buried, and we actually had to make new roads through the snow for access to our equipment,” Lachner added.
There were also environmental restrictions that had to be observed.
“Trees with trunks larger than eight inches in diameter could not be removed,” he explained. “In addition we had time constraints requiring the project to be completed by February because work could not continue during the spotted owl mating season”.