A key component of the Strawberry Aqueduct and Collection System in northeastern Utah, the North Fork Siphon was a 72-in.-dia, prestressed concrete cylinder pipe at the end of its useful life. This project replaced it with an 84-in.-dia, welded-steel pipe located parallel to the old one. The system ensures delivery of 50,000 acre-ft of water to Utah residents per year. Carrying water at approximately 285 cu ft per second from the Stillwater Tunnel, the siphon descends 700 ft down a 55-degree grade to the floor of a mountain valley bisected by the North Fork of the Duchesne River.

Photo by Blake Buehler

The adverse weather conditions in North Fork Canyon limited construction only to non-winter months until substantial completion in April 2021. The work included installing 154 pipe segments on two slopes with up to 70% inclines. There was only a 700-ft elevation difference between the siphon inlet-outlet and the valley bottom. Installation tasks on the steep slope were performed with a cable crane system to minimize the environmental footprint and avoid construction scarring on canyon faces. Whitaker purchased the equipment from a firm in Austria. It consists of two 80-ft-tall towers and spools of cable that can reach up to 2,000 ft.