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Chimney Hollow Reservoir – Dam Construction Stormwater

Larimer County, Colorado, USA

Chimney Hollow Reservoir - Dam Construction Stormwater

The Chimney Hollow Reservoir project is underway! Just west of Carter Lake in Larimer County, Colorado, our WaterTectonics field team is installing a water treatment system for construction of the largest asphalt dam in the United States. The Chimney Hollow Reservoir project is a collaboration between nine municipalities, two water districts and a power provider with the goals of: meeting the region’s future water demands; protecting the environment and wildlife; maintaining local food production; and preserving the region’s quality of life. The reservoir will store 90,000 acre-feet of water when built providing a firm yield of 30,000 acre-feet annually!

WaterTectonics is working with the project’s General Contractor, Barnard Construction Company, to handle permitting, treatment of construction site stormwater and treatment plant operations for grout water. Treatment of 500 gallons per minute includes chemical treatment, pH adjustment and use of four reaction/settling ponds.

During this four-year project, seasonal climate extremes and high winds were considered. With low temperatures dipping to -10° or below and overnight shutdown; heated chemical storage, custom heated wraps with anchors for external components and drain ports on interconnecting piping to prevent freezing. Due to multiple treatment steps, additional concerns included tankage for coagulation and settling needs where slower moving water would freeze over. Lined, sub-grade ponds were used for gravity return piping with circulation and other means to mitigate damage plant damage and related down-time.