Engineering firm Black & Veatch has been selected to deliver program management services to Denver Water on the Gross Reservoir expansion project in Colorado, US.

The expansion will more than double existing reservoir capacity and enhance water supply dependability for the 1.4 million people Denver Water serves in the metro area.

Black & Veatch will provide project controls, comprising of schedule, cost and document control, as well as construction management services.

The first filling of the reservoir is expected in April 2026. Dam construction will be carried out in three phases within four to five years, once permits are secured.

As part of the expansion, the height of the existing 340-foot-dam will be increased by more 131 feet, helping to increase reservoir capacity from 42,000 acre feet of water to 119,000 acre feet of water.

The project will also enable to increase the total output of Gross Dam’s hydroelectric power plant from 7.6MW to 8.1MW.

The expansion will increase Gross Reservoir’s capacity to 119,000 total acre feet by adding an additional 77,000 acre feet.

Around 72,000 acre feet will be used by Denver Water, while 5,000 acre feet will be offered to the environmental pool that provides additional water for South Boulder Creek during low flow periods.

It will also offer enhanced stream flow to a 17-mile stretch of South Boulder Creek located below the reservoir.

Black & Veatch project manager Greg Zamensky said: “Black & Veatch is supporting Denver Water’s vision of not only ensuring system resilience, but of providing clean, affordable and reliable water to customers for generations to come.

“The Gross Reservoir Expansion Project builds on our deep experience in supporting utilities as they execute significant, long-term projects."

Gross Reservoir Expansion Project program manager Jeff Martin said: “Back in the 1950s, the existing Gross Dam was designed and built to accommodate subsequent raises like the one we’re planning today.”