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HDD Project Completed In Cascade Mountains
Bore 3 was the reservoir shot. The drill rig was at the bottom on a level grade with the lake. We drilled down to a 45-foot depth and leveled off to span 950 feet under the lake. We then bored uphill about 1,158 feet following a plus 60 to 75 percent grade, depending on the bore layout, with an elevation change of 800 feet and notched out the hillside to stage tooling and pull product. This bore was one of the two extremely severe bores considering the grade changes required.
Bore 4 was 1,200 feet under a canyon, but the layout required a set-up location that prevented drilling directly across in a straight line -- the slope to the bottom was too steep to meet our bend radius. With plenty of room in our right-of way, we chose to drill around the outside of the canyon keeping within our running area. This one was a little easier with a minus 24 percent grade. We shot this bore from the side instead of setting up directly under the power lines. Upgrade to the exit point was plus 48 percent.
Bore 5, the timber bore, was across a canyon filled with thick forest that had to remain undisturbed. The set-up spot was on the side with the most room for equipment staging with both sides being about the same elevation. We shot down at about a negative 65 percent and slowly began to level off and hit the bottom of the canyon level in approximately 450 feet. We began a plus 24 percent up grade about three quarters of the way across the canyon to hit the bank on the uphill side that increased to a positive 80 percent to follow grade up the hill. We drilled out roughly 1,300 feet to the exit point. This bore had an elevation change of 245 feet to the bottom of the canyon on the machine side and about 280 feet of change to the exit point.
Bore 6 was called Dog Creek. We set up on the top side of the bore drilling down following minus 65 percent grade with an elevation drop of 700 feet. We shot down about 1,300 feet to level off to drill under the creek which was about 60 feet across with fast-moving water about three-feet deep. Past the creek, we began uphill at a plus 40 percent grade with a more gradual incline for about 900 feet with elevations reaching 300 feet. This was the project’s longest bore due to the ground conditions, and the grade changes required more distance to maintain the bore profile.