May 10, 2023

Managing Water On Site During Construction Makes a Big Impact

With Chimney Hollow Reservoir construction nearly half complete, managing the site’s water is vital to the construction process and other on-site water needs. Construction crews work hard to maintain a reliable construction water supply, control stormwater runoff and to make sure we only discharge clean water downstream from the site.

A stormwater management plan approved by the Colorado Department of Public Health and Environment (CDPHE) lays the groundwork for the discharge and control of all stormwater associated with construction activities. A temporary cofferdam helps to keep stormwater out of the active construction areas. Crews also operate an on-site industrial wastewater plant to treat water that has come in contact with active construction.

“We utilize a number of measures and best management practices to ensure that any water that runs off our site is clear of sediment and other contaminants,” said Joe Donnelly, Northern Water’s Principal Project Manager for the Chimney Hollow Reservoir Project. “Ultimately, we only discharge water from the site that has gone through a treatment plant, going above and beyond typical construction practices.”

On site, the largest use of water is seasonal dust suppression throughout the warm months of the year. Water trucks spray roads throughout the site to keep dust at a minimum. In addition, crews use non-toxic polymers to help hold dust particles together to cut down further on dust. Another large use of water is wetting embankment materials before they are compacted for the main dam embankment construction. According to Donnelly, this process is now in full production with round-the-clock work to raise the dam to its ultimate 350-foot height. A water line was also built from the local drinking water provider to supply potable water to the on-site offices for approximately 500 people working on site.

Spill prevention control measures, which are regulated through an environmental permit, ensure crews have at least two levels of containment around fueling stations and other areas that work with common construction fluids like motor oil and hydraulic fluid so that no contaminates enter water sources.

“Managing water on site is a small part of the project, but it is hugely important to our long-term project goals of providing a safe and reliable drinking water supply for the region,” Donnelly said.