The Tibble Fork Reservoir is an easy drive up American Fork Canyon in the Uinta-Wasatch-Cache National Forest. As a popular recreation site for the past 60 years, the reservoir filled in with a large volume of sediment, with over half of the sediment attributed to the Van Dugway Landslide located one mile upstream of the reservoir. With RB&G serving as the lead design firm, the implementation of the project was performed as a joint venture team involving Barrett Engineering and Horrocks Engineers. Cooperating entities included the U.S. Forest Service, Utah Division of Wildlife Resources, Utah Department of Transportation to the extent that it effected SR-144 in the project area, and a group of homeowners who have summer residences located downstream.
To meet applicable safety and performances standards, and to provide an additional 120 acre-feet of storage, sediment was excavated within the reservoir, the spillways were replaced and raised, a new toe drain was installed, and the dam embankment raised 15 feet. Harsh winter weather conditions challenged workers on this $8.6 million infrastructure project. It ultimately required crews to work around the clock, seven days a week to meet the May deadline.
One unique aspect was the construction of a three-foot-thick cement-bentonite slurry wall more than 70 feet below the reservoir bottom, which required use of a long-stick excavator with an 80-foot reach. The wall mitigates seepage below the dam wall, which was also raised 15 feet. A new concrete spillway structure was built so that water inflow could be diverted during construction.
Services: Dam design, geotechnical engineering, construction management, structural, materials testing and inspection