Mild winter puts Leavitt on fast track

A Saturday was required to complete one of the biggest undertakings thus far in the expansion of the Leavitt Reservoir northwest of Shell.
Rounding up nine of its mixing trucks, which it couldn’t have done on a weekday without shutting down one of its plants, Big Horn Redi-Mix delivered 29 loads of concrete to Leavitt site, where employees from Big Sky Civil Contractors and Montana Civil Contractors formed the foundation of a 90-foot outlet works tower.
The order called for just over 280 cubic yards of concrete, and adding to the challenge was the approximately 22 miles of road between the Greybull plant and the reservoir.  Each round trip took about two hours from start to finish.
“It was a lot of trucks, but everything went well,” said Big Horn Redi-Mix manager Jim O’Keefe, adding that several more pours are planned in the coming weeks as the building of the outlet works tower and the dam continues off Beaver Creek Road.
The goal of the reservoir expansion is to provide additional late-season water to irrigators on Beaver Creek.  To accomplish this, water from Bear Creek will be diverted, through a 42-inch pipe, into a wetland area and then the reservoir itself, where will be stored until it is released into Beaver Creek for late-summer irrigation use.
The outlet works tower will play a key role in its operation, according to Kevin Mininger of RJH Consulting, the engineering firm that was hired by the Shell Valley Watershed Improvement District to oversee the project.
“For one thing, it will serve as a multi-level withdraw system,” said Mininger. “We’ll be able to pull from the reservoir at three different elevations — from the bottom, from a third of the way up and from two-thirds of the way up.
“What that will allow the owners to do is optimize the water quality. Obviously the water at the bottom will be the coolest temperature, but it’s sometimes low in oxygen content.  Certain requirements will have to be met when releasing water to improve the aquatic habitat in Beaver Creek downstream.  Looking at the temperature at the dissolved oxygen, that gives the flexibility to blend water from different elevations or pull from a single elevation, wherever it makes sense.”
The other purpose of the outlet works tower will be to serve an emergency spillway.  The tower will feature two cavities. On one side will be the gates that regulate the amount and location where the water is withdrawn. The other will be open.  “That’s the spillway,” he said. “If the reservoir is full, there’s a precipitation event and water flows into the reservoir, it’ll drop into that tower and go out through the bottom to maintain the maximum pool of the reservoir without letting it fill too much.”
Don Scott, Montana Civil’s superintendent, said a 42-inch pipe at the bottom of the outlet works tower will be encased in concrete and stretch about 500 feet.
Ahead of schedule
The first quarter of 2024 couldn’t have gone much better than it did for SVWID and the contractors.
When bids for the four unique aspects of the project were opened late last year, the SVWID awarded three contracts that totalled $62.9 million.  Big Sky Civil and Montana Civil landed the largest of the four, Contract A, to construct the dam, outlet works, wetland mitigation area and recreational facilities, with a bid of $36.4 million. Those two companies also landed Contract D, to produce aggregate materials from the terrace borrow area, with a bid of $17.9 million.
Contract B, to construct the supply pipeline and associated structures, went to Mountain View Builders of Sheridan, which bid $14.6 million.
But at the time, the SVWID did not award Contract C, which is to construct a transfer pipeline and associated structures.  The lowest bid came in at $14.6 million, which was slightly outside the estimated cost $12 million to $14 million.
The Wyoming Legislature resolved the issue during its recent budget session, earmarking $56.8 million for the Leavitt Reservoir project as part of Senate File 75 (Omnibus water bill - construction).
With that, the total project cost rose to $88.85 million.  Of that, the state is paying $87.13 million. The remaining $1.72 million will be need to be repaid by the SVWID over a 50-year period and at an interest rate of 4%.
On site there were no complaints about the mild winter. “They were able to continue to get work done — especially in terms of aggregate production, which is several months ahead of schedule,” said Mininger. “They have produced 80% of the total amount of aggregate that will be needed for the project.
“The majority of what’s left is the rip rap, which of course is the slowest going.”
In a typical day, there are approximately 30 people working on site, with most being employees of the contractors although a few locals have been added to the crew, according to Mininger. He added that the peak will probably come in June.
“As they get more of the foundation of the embankment prepared, and have a little bigger work area, the contractors may increase their crew size,” he said.
The project is expected to require two years to complete, with most of the work expected done by the end of calendar year 2025.  Some pipework work may stretch into the early part of 2026, but Mininger is confident that the goal of filling the reservoir for the first time in the spring of 2026 will be met.