Crews Overcome Heavy Rain in May

June 25, 2023

Crews Overcome Heavy Rain in May

While the large amount of precipitation that Northern Colorado received since early May has been beneficial for multiple reasons, it wasn’t as welcomed by construction crews working on projects throughout the area.

At Chimney Hollow Reservoir, more than 15 inches of rain has fallen since the beginning of May.

A major precipitation event occurred during the second week of May, when 3.26 inches of rainfall was estimated over a 26-hour period. According to historic data, the storm was nearly a 100-year rainfall event at the site. This significant event was followed by a series of storms in late May and early June that totaled a year’s worth of precipitation in just a few weeks.

A cofferdam built early in the construction of the project has been able to capture the runoff from the small watershed around Chimney Hollow, however. Temporary pipes to convey water from the cofferdam around the construction site were set up to prevent damage to the main dam construction.

Stormwater is captured in the cofferdam on site from recent heavy rainfall.

Across the Continental Divide, the recent precipitation, as well as above-average snowpack runoff, led to a sharp increase in the flow of the Colorado River through Windy Gap Reservoir. At the site, crews are working to create the Colorado River Connectivity Channel to reconnect the river above and below the reservoir.

In early May, the river flow increased from 800 cubic feet per second (cfs) to about 2,200 cfs in about 48 hours. By doing so, the river overtopped an internal berm built last year, and water entered the area where the new channel will be located. As water overtopped the berm, some limited damage occurred. The full extent of the damage will not be known until water recedes next month.

Construction crews have been able to remain active at the site by working on the portion of the Connectivity Channel located below the Windy Gap Dam.