(I can tailor my presentation to whichever items would be of most interest, based on what other presentations are already being included in the conference. Below are brief descriptions of what could be included, so I could focus my presentation on any of these, and change the title accordingly.)
Millsite Dam dam is owned by the Ferron Canal & Reservoir Company in central Utah. Rehabilitation included several components to bring the dam up to current dam safety standards. This included: foundation dewatering and excavation, flattening the downstream face and adding a stability berm, constructing a new labyrinth spillway, and replacing the piecemeal outlet works. As part of the work, the dam was raised four feet to restore capacity that had been lost from sedimentation. A unique internal filter and drain system was used in order to leave a large portion of unfiltered cobble/rock zone in the main dam section rather than removing the majority of the dam. The labyrinth spillway included scaled physical modeling to opitimize the design of the new spillway, which includes an impressive 60-foot waterfall at the discharge end of the spillway chute.
Challenges for the project included: innovative design and excavation of bedrock for the new labyrinth spillway; working with multiple public and private entities because of the project impacts; a golf course at the toe of the dam that needed to have two golf holes redone; a nearby state park that needed portions of the park raised because of the raised water level; outlet connections to open canals, pressurized irrigation pipelines, a city, and a power company; involvement by several state and federal agencies for design and approval; federal and state funding; dealing with a local endangered cactus impacted by the raised water level; and more.
One of the main challenges was the result of a design error in the concrete for the labyrinth spillway. The project was originally expected to take less than two years, but ended up taking over 6 years. The spillway concrete didn't include enough reinforcement for temperature and shrinkage stresses. This was discovered after the entire floor and a portion of the walls had been completed. Additional efforts were needed to treat the already placed concrete, and the remaining walls needed to be redesigned, which included extensive analyses and review. This created the need for innovative solutions to pass spring runoff through the spillway during redesign and additional construction.
