Raise and Roll in Colorado: Doka supports largest roller-compacted concrete dam expansion in U.S. history

As part of an effort to manage the region’s long-term water supply, Denver Water is raising the 70-year-old Gross Reservoir from 340-ft. to 471-ft. The rise will dramatically increase the capacity of the reservoir, from approximately 42,000-acre ft. to 119,000-acre ft.

Doka’s infrastructure group collaborated closely with the joint venture team of Kiewit and Barnard to develop a custom formwork solution that addresses the unique challenges of this large-scale project. The formwork system incorporates horizontal adjustment to maintain tie spacing as the dam face steps back with each lift, ensuring both aesthetic alignment and structural integrity.

Doka’s innovative approach combines custom and standard girder forms, creating a flexible, easy-to-move system that supports 24/7 progress on the jobsite. The formwork solutions include Xclimb 60 for the training wall girder formwork, Framax S Xlife panels on the lower training walls and trailing platforms constructed from WS10 and H20 Beams T. The formwork is designed to be assembled in a way that allows four one-foot lifts per 24 hours. As the project progresses, Doka will also install DokaXact Load and Pressure sensors for real-time concrete monitoring.

"Doka’s involvement in the Gross Reservoir expansion project underscores our commitment to engineering excellence and innovation in infrastructure," says Michael Kennedy, CEO of Doka USA. “The challenges posed by the dam’s stepped design and the need for precise alignment with the existing structure required us to engineer a formwork solution that could adapt to varying pressures while maintaining efficiency and safety. By combining custom and standard girder forms, our team delivered a system that not only supports the massive volumes of roller compacted concrete but also helps ensure the structural integrity of the dam as it rises.”

According to Denver Water, the multi-year expansion project is the largest dam raise in the United States and the largest roller-compacted concrete (RCC) dam raise worldwide. About 725,000 cu. yds. of RCC and over 90,000 cu. yds. of conventional concrete will be required to complete the project. The project scope also includes 118 concrete steps that rise from the bottom of the existing dam to the new dam crest.

"Every project comes with unique challenges, and the Gross Reservoir expansion is no exception,” says Michael Kennedy. “Our team is proud to partner with everyone involved to overcome those challenges in support of this critical infrastructure investment, which will help safeguard the region’s water supply for generations to come."

The Gross Reservoir project is scheduled for completion in 2027.