Bellvue Transmission Pipeline North Segment – Phase 2

Completed in 2018 by Southland Contracting, the Bellevue Transmission Pipeline North Segment – Phase 2 Project consisted of installation of approximately 2,500 linear feet of 88-inch tunnel – supported with ribs and lagging with a carrier pipe of 60-inch welded steel cylinder pipe with poly coating and mortar lined. There will be 4 access shafts ranging from 40 – 50 vertical feet deep along the tunnel alignments. The project also has approximately 2,800 linear feet of cut and cover work installing the 60-inch welded steel cylinder pipe. Ground conditions range from boulders, cobbles, gravel, sand, clay and sandstone will be encountered during shaft and tunnel excavation. The rock portions of the tunnel consist of rock with unconfined compressive test between 1,000 psi and 21,000 psi with an average of 6,000-7,000 psi. Groundwater was also a problem as the alignment is adjacent to the Cache la Poudre River. Each access shaft is expected to encounter flows around 1,000 gpm. Dewatering wells will be installed around each shaft and along the alignment of the open cut.