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E-Newsletter | August 2023 |
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 New Video Recaps 2 Years of Construction as Project Hits Halfway Mark
The largest reservoir that’s been built in the U.S. this century has reached its halfway point in construction. Work on Chimney Hollow Reservoir kicked off in August 2021, and two years later the project remains within a couple weeks of its summer 2025 targeted completion date.
As the project hits the two-year mark, crews have built up 120 feet of what will eventually be the 350-foot-tall main dam at Chimney Hollow Reservoir, while progress also continues on the inlet/outlet tunnel, saddle dam, valve house and other critical infrastructure components.
In this new video, Northern Water and Barnard project managers touch on the many successes the project has seen in the first half of this four-year construction project.
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Employee Spotlight: RJ Roos
When Barnard Construction was selected as the general contractor for the Chimney Hollow Reservoir Project in August 2019, Chimney Hollow Reservoir Project Operations Manager RJ Roos was one of the first assigned to the project. He had recently finished building a new dam in Labrador, Canada, and returned to Bozeman, Mont. waiting for the next project. A couple of years later, the Chimney Hollow project began, he and his family moved to Berthoud, which would be their new home for the next four years.
Throughout his 20-year career with Barnard, Roos has worked his way from a project engineer to a field superintendent to general superintendent and now operations manager. The 13 projects that Roos has worked on have taken him and his family all over the United States and Canada.
In what could be called “full circle,” Roos started his career with Barnard in 2003 as a project engineer working on the Pleasant Valley Pipeline, a joint effort between Northern Water, Fort Collins, Greeley and the Soldier Canyon water districts to increase the flexibility and reliability of water deliveries. Twenty years later, he is back in Northern Colorado working on another Northern Water project – this time, a much bigger project that comes with a lot more responsibility.
Helping construct Chimney Hollow Reservoir has been the highlight of his career. It’s a large-scale project with many components that provide daily challenges and rewards. But what he enjoys most about the project, though, is not the actual construction work.
“I enjoy the people part of it – managing and helping people grow. I like pushing them to do things that they don’t think they can do or ever thought they could do,” Roos said.
When he’s not at work, Roos enjoys spending time with his wife and kids, including camping, riding dirt bikes, hunting and hiking. After this project, Roos anticipates that he will move back to his home state of Montana and is looking forward to being home for a while.
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 Concrete Spillway Taking Shape
Throughout the past year and a half, crews have been working on the reinforced concrete spillway on the left (west) abutment of the main dam. Despite setbacks due to this spring’s heavy rain events, the project has made significant progress. Since completing excavation, 1,700 cubic yards of concrete have been placed on the bottom “tray” of the spillway, which includes approximately 29 individual slabs that combine for 725 feet of its total length of 2,907 feet. Five box culvert sections (the concrete wall and roof enclosures) have been placed, resulting in 125 feet of fully completed spillway. Construction of each 25-foot section of box culvert takes about one week using a slipform machine. The forms are flown in by crane and prepared with rebar, a bulkhead and water stop before concrete is placed. Once this occurs, the concrete must be cured to 75 percent strength before the slipform equipment can be removed. To help speed up production time, two more slipform machines are in the process of being added.
Once complete the spillway will safely convey precipitation and runoff from storm events, up to the probable maximum flood (PMF), around the main dam embankment. The PMF storm event estimate for Chimney Hollow Reservoir’s dam is the first in Colorado to incorporate recently developed climate change impacts to ensure the dam remains safe in the future. This state-of-the-art design minimizes the risk of failure in the event of spillway operation. Because Chimney Hollow is an off-channel reservoir and not located on a major river system, the spillway is quite small relative to the size of the main dam. The spillway has a 10-foot-wide chute designed to accommodate a skid steer loader for inspections and maintenance. The length is approximately 3,600 feet and contains about 12,000 cubic yards of reinforced concrete, all produced on site.
Most of the spillway will be constructed below the existing ground surface to keep the spillway on a solid rock foundation and to maintain the aesthetics of the site.
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Valve House Slabs Complete
In late July, crews placed the final concrete slab for the valve house to provide solidity between the ground and the four-story building. Each of the seven slabs contains roughly 300 to 400 cubic yards of concrete and is 6 feet thick, unlike the standard 4-inch slabs in a typical house. The immense pressure of water descending through the Colorado-Big Thompson Project (C-BT) and Chimney Hollow systems from Pinewood Reservoir require robust slabs that act as thrust blocks to secure the valve house infrastructure.
Beginning in March, crews blasted and excavated approximately 72,000 cubic yards of material, then inspected and cleaned the area. Prior to placing the concrete slabs, crews installed steel rebar to reinforce structural stability below the valve house. Completing the valve house foundation – a key feature of Chimney Hollow’s water infrastructure – enables crew members to move on to other tasks and helps ensure project success.
“The valve house is key for delivering water to the system and the slabs are a critical part of its design,” said Jeremey Deuto, Northern Water’s Senior Project Manager for the Chimney Hollow Reservoir Project.
With approximately 50 valves up to 6 feet in diameter, the valve house is designed to safely control the flow rates and pressures between the C-BT Project’s Pinewood Reservoir, Chimney Hollow Reservoir and Carter Lake.
“The valve house is the heart of the water infrastructure for Chimney Hollow,” Deuto said.
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 Participant Spotlight: City of Loveland
The City of Loveland is the third largest participant in the Chimney Hollow Reservoir Project and has exactly one-ninth of the storage capacity with 10,000 acre-feet. Once completed, this reservoir will be a critical element in Loveland’s water supply portfolio.
“Water stored in the reservoir will be hugely beneficial to Loveland. In the face of a host of emerging water supply risks, Chimney Hollow is a critical element ensuring a reliable and sufficient water supply for the city,” said Loveland Water & Power Water Resources Manager Todd Hanlin. “Chimney Hollow Dam and Reservoir represents a historic achievement in the water supply development for the entire Northern Colorado region.”
Although water will not be delivered from Chimney Hollow Reservoir for a few more years, project participants have been actively working on and prioritizing their conservation efforts with plans to cut more. Hanlin said Loveland is currently reviewing all its water conservation programs and activities to determine the most effective tools for the future. It plans to reduce the five-year average of gallons per capita per day (GPCD) from 163 to 155, which is a 5 percent overall reduction. Additionally, Loveland plans to reduce water use by 322 million gallons per year beyond what it would use if no conservation activities were performed.
With a population of just over 77,000, Loveland residents have the added benefit of a new reservoir and open space right in their backyard. Recreation will be managed by Larimer County and is likely to include wakeless boating, fishing, hiking and horseback riding.
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 County Road 18E Clean Up
Northern Water, Barnard Construction, Black & Veatch and Stantec employees lent a hand in the volunteer trash pickup along Larimer County Road 18E on Saturday, Aug. 5.
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Stay Connected
Visit the Chimney Hollow Reservoir Project website for the latest news and project highlights.
Also, connect with us on Facebook and Twitter!
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About Chimney Hollow Reservoir
The Chimney Hollow Reservoir Project is a collaboration between 12 Northeastern Colorado water providers to improve the reliability of, or make firm, water supplies from the Windy Gap Project. Chimney Hollow Reservoir will be located just west of Carter Lake in Larimer County to provide dedicated storage to supply a reliable 30,000 acre-feet of water each year for future generations.
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