Hanksville Canal Company Diversion
The Hanksville Canal Company Diversion Project replaces the historic diversion structure that failed in 2006 with a new concrete dam on the Fremont River, located roughly two miles west of Hanksville, Utah. The new dam is designed to provide critical floodwater storage during high-flow events and to ensure reliable delivery of seasonal irrigation water for local agriculture.
Malcolm constructed a cutoff wall beneath the new diversion dam foundation to control groundwater seepage and mitigate long-term dissolution of gypsum in the foundation rock. The wall consists of 264 interlocking secant concrete piles, each 1 meter (39 inches) in diameter and extending 20 to 46 feet deep.
In addition, Malcolm performed stitch grouting to seal and strengthen bedrock faults underlying the foundation. This work reduces permeability, limiting potential gypsum dissolution and erosion. The stitch-grouting program included three rows of 3-inch-diameter holes drilled to depths of up to 80 feet, followed by water-pressure testing and pressure grouting using balanced, stable Type V or microfine cement grout.
