Engineers solve major challenges to deliver largest US Asphalt Core Rockfill Dam (ACRD)
January 23, 2026
In New Civil Engineer, Don Montgomery discusses detailed design elements of the largest ACRD in the US: Colorado’s Chimney Hollow Reservoir Project
Main construction works have been completed, on schedule, for the Chimney Hollow Reservoir in northeastern Colorado—the largest dam to be constructed in the state in the last 50 years, and the largest US Asphalt Core Rockfill Dam (ACRD) in the US. The reservoir will help local water suppliers meet the needs of the region’s growing population and cover gaps in the network. Located just west of Carter Lake near Loveland, the reservoir will serve 12 providers with around 825,000 customers.
The construction of this dam was unusual for the US. New Civil Engineer interviewed Stantec’s Don Montgomery, our client Northern Water, and contractor Barnard, to examine how the dam was built and discuss the various obstacles the project team had to overcome.
