Daly Ditch Siphon

In Hamilton, MT the large, wooden irrigation system that supplied water to the Bitterroot Valley for over a century recently needed replacement. The obvious solution was to span the canyon with a modular steel bridge, but this proved to be too costly for a 200’ bridge. To meet function and budget requirements, a complete design change was needed. After considering various options, an aerial span was suggested. To accommodate the length of the clear span, three precast piers were installed to support the bottom of the siphon. For corrosion protection and superior hydraulic performance, a 60” Aluminized Type II welded-seam Spiral Rib was utilized to pass the necessary volume of water through. Additionally, the welded-seam pipe, bands, and gaskets equipped with rods and lugs provided the most watertight scenario possible.

The flume along the hillside also required extensive repairs and was replaced with a 73”x55” Aluminized Type II welded-seam pipe arch to convey irrigation water and terminate back into the ditch. Precast concrete inlet and outlet structures were used to transition the different segments of the system. A steel trash rack was used to prevent debris from flowing through the system and acted as a human safeguard to prevent a person from being sucked into the siphon. TrueNorth Steel worked closely with the Daly Ditches Irrigation District from the project’s start to finish. From rough sketches to plans and specs to reality, this project helped provide critical infrastructure to supply the Bitterroot Valley with irrigation for many years to come.