Dec. 10, 2024

Chimney Hollow Project Nearing Operational Readiness

Northern Water’s Municipal Subdistrict staff and key project contractors are making great progress on getting the Chimney Hollow Reservoir Project ready for operations in 2025. As the main dam nears completion and other key project elements are wrapping up, getting the new reservoir ready for operation isn’t as simple as opening the valves and letting water flow into the reservoir. The carefully calculated process has taken a lot of work to get to this point.  

Joe Donnelly, Principal Project Manager for the Chimney Hollow Reservoir Project, said final drafts of operational procedures are in review alongside the State of Colorado’s Engineers office, Stantec - the project designer, and the U.S. Bureau of Reclamation on the use of the Colorado-Big Thompson Project infrastructure to deliver water to the new reservoir from the West Slope.  

“It’s exciting to get to this point of being close enough to start testing components of the project,” Donnelly said. “The last piece of conveyance infrastructure is in the works with the inlet/outlet tower going vertical. This is certainly a fun time to be at Chimney Hollow.”   

Stantec has finalized the first-fill plan for the project which will limit how quickly we initially fill the new reservoir. This plan is with the State Engineer’s office, Division of Dam Safety, for final approval. The process will include determining a maximum rate of water rise that is acceptable for the reservoir and then setting hold points, or pauses, in the filling to see how the dam responds at select water levels. As part of the plan, they have scheduled four hold points to have water levels sit for three to four weeks to see the response and confirm the dam is performing as expected.    

Barnard Construction, the project’s general contractor, has also finalized a draft commissioning plan that is in for approval. As part of their efforts to get the project operational, all electrical and mechanical operations will need to be tested locally and using a remote SCADA system for operations. The valves are first tested in dry conditions to make sure everything works properly, followed by wet testing to ensure there is no leakage or problems operating under pressure.   All valves and major equipment will be tagged in the Northern Water’s asset management system to manage preventative maintenance, which also interacts with our GIS team to help track items. 

Northern Water’s Instrumental Control and Electrical Engineering Department has been designing all the controls that will be installed in the valve house beginning in December. 

“It’s a delicate balance of water delivery to Chimney Hollow which exists in the middle of the overall C-BT Project,” Jim Nguyen, Operations Superintendent for Northern Water, said. “Because this is Windy Gap water, there is more coordination of moving water into this system – ultimately more coordination than any other reservoir in the C-BT Project.”  

Nguyen said a great relationship with Reclamation is what will make this project work.  

Northern Water Operations crews have also been on site at Chimney Hollow since the beginning of construction learning about the key reservoir components. Through a program colloquially named ‘Chimney Hollow University,’ Northern Water’s three operations crews (mechanical, electrical and civil) visit the site monthly for a half-day training. Some sessions are in a classroom setting while others are in the field. By regularly bringing the crews on site, they are gaining first-hand experience of the reservoir components they will maintain and operate once it is built. 

Once Barnard conducts commissioning in spring, Northern Water crews will conduct final scenario testing with real water to ensure full operational readiness of the new reservoir.