Colorado's Coal Ash: A Toxic Legacy Surfaces

Colorado regulators are examining Xcel Energy's final plan to remediate groundwater contamination stemming from long-term coal ash disposal at the Valmont Power Station. This ambitious project, potentially commencing construction in late summer, addresses pollution that has spread beyond the company's property and impacted nearby residential wells.

The proposed system represents a novel approach in Colorado, designed to extract contaminated groundwater for treatment. Despite this, environmental advocates express reservations, suggesting the cleanup might be incomplete if a second, older coal ash landfill also contributes to the pollution.

Decades of coal combustion at the Valmont Station generated approximately 1.6 million cubic yards of coal ash, stored in landfills east of Boulder. This waste contains hazardous substances like arsenic, lead, and chromium. Investigations have revealed that a landfill built in 1993 has contaminated groundwater since at least 2017, with evidence of a plume migrating towards residential areas.

Xcel Energy aims for the extraction system's installation to begin in late summer and conclude in the fall, pending state approval of the final design. This system is part of a broader remediation effort that will eventually include removing coal ash from the 1993 landfill, a process anticipated to span about a decade.

Questions persist regarding a second coal ash landfill located northeast of the power plant. This "legacy landfill," initially exempt from federal regulations, is now subject to expanded EPA rules. While Xcel has not yet proposed a remediation plan for this site, its potential role in contamination remains unclear, as it lacks liners and groundwater monitoring systems.

This legacy landfill could pose an ongoing threat, potentially leaking pollutants into groundwater for years. Critics argue that neglecting this source might lead to a continuous cycle of groundwater treatment without achieving true cleanliness. The regulatory landscape for such legacy landfills is uncertain, with potential rollbacks of federal requirements that could shift the burden of oversight to state regulators or Xcel itself.

The groundwater treatment plan involves a network of extraction wells and collection trenches to intercept and capture contaminated groundwater. This captured water will be transported to a treatment facility. Xcel is also implementing a water augmentation plan to replenish extracted groundwater and mitigate impacts on downstream water rights.

Construction of the system is expected to take five to seven months. With necessary permits, including those from Boulder County, the system could become operational by early 2027.