Kiewit has completed all roller compacted concrete (RCC) placement at the Gross Reservoir Expansion Project in Colorado, marking a major construction milestone for the dam-raising scheme.
The contractor said the work has increased the height of Gross Dam by 130ft (40m), bringing it to 470ft (143m) and making it the tallest dam in Colorado. Only one vertical foot of structural concrete slabs remains to be placed before the dam reaches its final design height.
As of June 2026, more than 744,000 cu yd (569,000m³) of RCC and 59,000 cu yd (45,000m³) of conventional concrete facing have been placed on the project.
The Gross Reservoir Expansion Project is designed to increase water storage capacity for the Denver metropolitan area. The dam raise is one of the largest RCC dam construction projects currently underway in the US.
With RCC placement now complete, construction activities will focus on the remaining structural concrete works at the dam crest, spillway and stilling basin, along with installation of mechanical, electrical, instrumentation and security systems.
According to Kiewit, overall construction is expected to be completed in October 2027.
