Weber Basin Water Conservancy District (District) covers 2,800 square miles and serves over 700,000 residents. The Davis Aqueduct was constructed in the 1950s and Reach 1 parallels the Wasatch Fault, delivering raw water to the District’s Davis North Water Treatment Plant as well as to farmers in two counties for irrigation purposes. Davis Aqueduct Reach 1 (DAR1) is the first, and most critical, of several planned large-diameter parallel conveyance pipeline projects over the next decade to address seismic resiliency, provide redundancy, and accommodate growth.
To avoid most of the seismic hazards, liquefaction, and landslide areas for the new conveyance pipeline, Brown and Caldwell (BC) conducted a route evaluation study and recommended conveyance pipeline alignment. The proposed route included crossing two major canals and US Highway 89 to maximize hazard avoidance. Planning the highway crossing took almost a year with close collaboration between Utah’s Department of Transportation, BC, the District, and the contractor. The crossing plan had to be completed in two consecutive weekends while leaving one direction of traffic completely open. The team successfully completed the crossing construction in snowy, wet weather, using multiple crews for continuous construction, and the highway reopened several hours early on the second weekend.
BC oversaw surveying, extensive geotechnical investigations, a corrosion study, and NEPA clearance for the new route. BC designed 2.2 miles of 72-inch diameter welded steel pipe and a small pump station at Military Springs to capture seepage and Gateway Tunnel drainage, maximizing the available water resources in that area.
The new BC-designed 60-mgd pump station provides multiple redundancies, with one 20-mgd pump install at 345 feet of discharge head to save on capital and maintenance costs. The pump station was designed with the option of several pumps, which can be added as needed by the District. Nestled between the US-89 frontage road and the irrigation canal, the pump station can pull water from either the Gateway Tunnel or the canal to supply the District’s Davis North Water Treatment Plant. It can also return water to the irrigation canal in the event of an upstream failure.