Rocky Mountain Power recently completed construction of a new 11-mile-long, 3-kV power transmission line in West Jordan, Utah. The new line was constructed within the existing right-of-way, only 25 feet from the existing overhead lines. The Soilmec SR-50 hydraulic rotary rig with a low-headroom attachment was instrumental in constructing the foundations and completing the project.
“It’s very tricky adding transmission poles near energized lines,” notes Phil Stilson, president of Most Wanted Drilling, Farmington, Utah, the drilling subcontractor for the job. “By using the Soilmec low-headroom attachment on the SR-50, we saved a lot of time. In the past, the utility would have had to spread the energized lines so we could move and work around them. This is a slow and potentially dangerous process. Those lines are packing a lot of juice.” For the West Jordan project, spreading the lines was not necessary because the low-headroom attachment could be driven under the existing lines.
Most Wanted Drilling installed 6-foot- to 12-foot-diameter caissons for the monopole powerline every 300 feet. More than 100 foundations were built, with depths ranging from 35 feet to 85 feet.