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Mountain Pass Drilling: Contractor Beats The Snow To Install Fiber In Washington
The system employs an inner rod to drive a rock bit, and an outer pipe steers the downhole tool for drilling pilot holes and provides rotary torque for backreaming. It is designed to deliver maximum downhole horsepower to the bit. The system also enables simultaneous drilling and steering through rock and rocky soil while requiring no more drilling fluid than conventional equipment.
All HDD equipment on the project was AT models -- mud motors never were used. Directional drilling was the only feasible method to use in many areas where the roadway had no shoulders and there was no room for excavation or plowing equipment to operate.
Construction began in July 2012 with two Apex-owned, 30,000-pound pullback JT3020 AT drills and a backhoe crew for tie ins, said Gagner.
“Over the next two weeks the project blossomed to nearly full capacity as we employed seven of our own drills (six JT3020s and one 100,000-pound pullback JT100 AT) and three subcontractors, each with one HDD unit,” Gagner continued. “We were installing 1 1/4-inch SDR 9, ribbed inner duct to house the fiber optic cable. With duct in place, cable was installed hand-hole to hand-hole by Apex subcontractor Precision Fiber.”
Once the East side of Sherman Pass was completed, Apex and subcontractors descended off the west side of the mountain and moved equipment into position for building the western segment.
At the projects' peak, 12 drill crews, six backhoe crews and two plow crews were used. APEX was able to complete all work most likely to be impacted by winter weather before the snow arrived.
Said Gagner, “Over the course of the five-month fiber build, approximately 360 individual drill shots were completed, the shortest bores measuring 60-feet in length while the longest bore measured 1,480 feet. The average bore length on the project was 300 feet.”
Walk-over electronic tracking equipment was used on all HDD installations.
In addition to difficult surface terrain and rocky subsurface conditions, access to work areas was difficult.
“Highway 20,” said Gagner, “is a two-lane road through mountainous country, with minimal shoulder room for construction equipment. Extensive traffic control set-ups were required for nearly all underground work performed, usually consisting of two flaggers, one pilot car and one supervisor. Traffic control was subcontracted to Altus Traffic.”
The last bore and conduit installed was completed just before Thanksgiving Day 2012.