BOULDER, Colorado — Xcel Energy’s effort to clean up decades of coal ash contamination at its Valmont Power Station near Boulder is advancing through regulatory review, but environmental advocates and local residents continue to raise concerns about groundwater pollution and the potential role of a second coal ash landfill at the site, according to state records and company statements.
Colorado regulators are reviewing Xcel’s final groundwater remediation plan, which could move into construction as early as late summer if approved, according to documents filed with state environmental authorities and statements from the utility. The project is intended to address contamination linked to coal ash disposal that has affected groundwater beneath and beyond the company’s property.
The proposed cleanup system would pump contaminated groundwater from beneath the site and transport it for treatment and disposal. Xcel spokesperson Sydney Isenberg said the company is awaiting state approval of the final design and expects installation of the extraction system to begin later this year. “We are currently anticipating approval from the state on the final design for that remedy,” Isenberg said in a statement.
Coal ash, a byproduct of coal-fired power generation, contains contaminants that can include arsenic, lead, chromium, lithium and selenium. The Valmont facility, which burned coal for decades before transitioning away from coal operations, contains large volumes of ash stored in landfills near Boulder. State and federal regulations require Xcel to address both the source of contamination and the affected groundwater, according to regulatory documents.
Public health officials have supported efforts to prevent further migration of contamination. Erin Dodge, a water quality program coordinator with Boulder County Public Health, said in a statement that “the timely installation of a well-designed groundwater treatment system is critical to help prevent the continued or further spread of groundwater contamination.”
However, environmental groups argue that the remediation plan may not fully resolve pollution concerns if another coal ash landfill northeast of the power plant is also contributing to groundwater contamination. The landfill became subject to expanded federal coal ash regulations in 2024, though cleanup requirements and timelines remain under review. Xcel has said the extent of that landfill’s contribution to groundwater contamination remains uncertain.
Residents have also voiced concerns about potential air-quality impacts from future excavation of coal ash during a broader cleanup effort expected to take years. Community members and local officials have sought independent air monitoring as plans for ash removal advance.
As of Friday, Colorado regulators were continuing their review of Xcel’s groundwater treatment proposal. The company said additional federal, state and local permits are still required before construction can begin, with the treatment system potentially entering operation in 2027 if approvals are secured.
