Coal Ash
Coal ash is a byproduct of the combustion of coal used to produce power at power plants. Fly ash, bottom ash, slag, and flue gas desulfurization materials are all terms that represent the different types of coal combustion residuals (CCR). Coal ash is disposed of in wet form in large ponds (surface impoundments) and dry form in onsite or off-site landfills.
Once an impoundment area has reached capacity or is to be closed for other reasons, the water is drained, and the ponds are dredged. The dredged residuals are then deposited on-site in designated landfills. Coal ash can contain heavy metals and other toxic substances that can harm health if inhaled or ingested. Boulder County Public Health is working with state and federal regulators to better understand and mitigate potential health risks at this site.
Groundwater Monitoring for Contamination and Corrective Measures
Xcel Energy’s ongoing groundwater monitoring at the Valmont Power Station identified localized groundwater contamination near the coal ash landfill and a few neighboring properties. Xcel is required to clean up and permanently resolve the groundwater contamination at Valmont Station. Their proposed plans for addressing the groundwater contamination are outlined below, along with an overview of Boulder County Public Health’s role in the project and information on how the public can share their voice on the cleanup effort.
In 2020, Xcel’s groundwater monitoring at the Valmont Power Station detected two contaminants, lithium and selenium, present in concentrations in some monitoring wells, which were above what is considered safe groundwater protection standards. The standards are set by the Colorado Department of Health and Environment and the Environmental Protection Agency to protect public health and the health of our aquifers. This contamination is linked to the coal ash stored in the landfills on the property.
Additional testing from several privately owned wells on neighboring properties to the northeast has also found concentrations of lithium and selenium above groundwater protection standards. Lithium and selenium are naturally occurring elements in rocks, soil, and groundwater. However, they can be potentially harmful if large amounts are ingested or if there is long-term exposure. The groundwater contamination is not currently believed to impact any public water supplies.
Plans for Remediation
Xcel is developing plans with a contractor to clean up the existing groundwater contamination and permanently prevent any future contamination. The proposed remediation plan involves a combination of groundwater pumping and treatment and source removal from the coal ash landfill. Xcel intends to apply coal ash in a beneficial reuse project, where 85% of the coal ash from landfills will be used to produce a product sold into the local ready-mix concrete market. Coal ash partially replaces cement, which must be manufactured from mined limestone. Boulder County Public Health recognizes the potential air quality concerns related to the excavation and processing of the coal ash. We are working to advocate for best management practices and policies to address possible impacts on air quality and reduce potential community exposure.
Xcel has been sharing information about site conditions and its proposed groundwater action plan with Boulder County Public Health, the Colorado Department of Public Health and Environment, and the Environmental Protection Agency.
Health Information about Selenium and Lithium in Drinking Water
Additional resources from Xcel Energy
