|May 1, 2014
Lower Dry Fork Dam modifications completed
By Adriana Fehrs
The newly rehabilitated Dry Fork Dam was tested once the reservoir waters filled back up. The last steps of the modifications for the Dry Fork Dam involved installing a new concrete impact basin, gate house, 200 feet of six foot diameter concrete pipe, completing the stability berm, sand filter, and toe drain. CSKT Safety of Dams finished up the project on April 2. (Photo courtesy of Dan Lozar, CSKT Safety of Dams Program Manager)
LONEPINE — Construction of the final ‘stage two’ of the Dry Fork Dam finished on April 2 after months of digging, setting rebar, pouring concrete, and dealing with the harsh winter
The original earthen Dry Fork Dam, located six miles north of Hot Springs on the Dry Fork Reservoir, was built in 1921. The U.S. Geological Survey (USGS) writes, “The Dry Fork Reservoir is one of a group of four reservoirs known as the Camas Reservoirs located in the Little Bitterroot River basin operated for irrigation and recreation.” In 1935 the dam was rebuilt, and up until 2008 the dam has undergone regular maintenance, staving off any major issues. The BIA owns the dam, and CSKT is compacted to run the Safety of Dams Program on the facility.
In late January the CSKT Safety of Dams and local contractors work vigorously into the night to complete the Dry Fork Reservoir before the spring run off and irrigation season. (Photo courtesy of Dan Lozar, CSKT Safety of Dams Program Manager)
In the fall of 2007 ‘stage one’ of the rehabilitation for the Dry Fork Dam began. Mungas Co Inc., of Philipsburg, was responsible for all construction for stage one. Mungas put in a new sand filter, toe drain, and stability berm. All of the new construction helped to add stability to the earth dam. Construction of stage one ended in 2008. Dan Lozar, CSKT Safety of Dams Program Manager, says, “Prior to ‘stage one’, there had been enough maintenance on the dam to keep it running, but in the last years running up to 2007, the dam really started to show its age and downstream instability became an issue.”
During the harsh winter months, the Saftey of Dams worked fast to finish stage two of the modifications to the Dry Fork Dam outside of Hot Springs. The project was completed on April 2. (Photo courtesy of Dan Lozar, CSKT Safety of Dams Program Manager)
In Spring of 2013, the CKST Safety of Dams Program bid on a contract for the final ‘stage two’ of the rehabilitation for the dam. Lozar says, “The rehabilitation of the dam was a long process. It had to be broken up into stages to make it more financially feasible.” S&K Environmental (SKER) won the contract, and on-site construction was underway by late August 2013. The project was designed by the U.S. Bureau of Reclamation (USBR) of the Department of the Interior (DOI). “The [USBR] had very strict specifications for the construction, and S&K Environmental was able to meet all of those specifications,” says Lozar.
By mid October 2013 the CSKT Safety of Dams had already dug out a large trench for the modifications that would be made to the Dry Fork Dam. The final stage two of the rehabilitation ended April 2 on time. (Photo courtesy of Dan Lozar, CSKT Safety of Dams Program Manager)
Stage two of the Dry Fork Dam rehabilitation proved to be a team effort. SKER, CSKT Safety of Dams, local engineering firms and subcontractors all played a part on the project. “It was really a team effort. I applaud SKER for their ability to use all local contractors and engineers,” says Lozar. The remote location of the dam made collaboration a huge part of the project. “Logistics were tightly scrutinized because of how far out we were, and communication was essential. We had to make sure everything ran smoothly.”
Local contractors and engineers for CKST Safety of Dams Program make modifications to the Dry Fork Dam for stage two of the project. Workers had to follow strict specifications set by the U.S. Bureau of Reclamation (USBR) of the Department of the Interior (DOI). (Photo courtesy of Dan Lozar, CSKT Safety of Dams Program Manager)
The last steps of the rehabilitation involved installing a new concrete impact basin, gate house, 200 feet of six foot diameter concrete pipe, completing the stability berm, sand filter, and toe drain. Construction didn’t come to a halt, regardless of the weather. SKER and CSKT Safety of Dams had a small window of opportunity to work with. Construction had to be done during the time when the reservoir water receded and before spring run-off and irrigation season. Lozar says, “It was difficult, we had a hard winter, but essentially we got the project done in time.”
Now, the multiple stages to finish the dam modifications are complete and the Lower Dry Fork Reservoir is filling up. CSKT Safety of Dams is currently finishing up their ‘First Filling Plan’ – a 24 hr/day monitoring of the dam when it refills for the first time – which is done as a precautionary measure. Lozar says, “Things are looking good.”