Responsibly managing our coal ash facilities is a priority.
When coal is burned to generate electricity, it leaves behind a solid residue—coal ash, similar to ash in a wood burning stove. We’ve decreased coal ash output from our operations 55% since 2005 by generating electricity with cleaner resources, including natural gas, wind and solar energy. As a result, we’ve reduced the amount of coal ash that we store or dispose in permitted landfills on our properties. This progress will continue as we transition away from coal and achieve our vision of providing 100% carbon-free electricity by 2050. We have proposed ending the use of coal by year-end 2030.
We operate in states that have effectively regulated coal ash storage and disposal activities for decades. These local rules specify construction and operating standards for facilities where we store and dispose of coal ash, and they ensure routine inspections and groundwater monitoring. In addition, the U.S. Environmental Protection Agency began regulating coal ash as a nonhazardous waste in 2015 under its Coal Combustion Residuals (CCR) Rule, which establishes national minimum standards for the design, operation and closure of these facilities.
Upper Midwest Region Data and Information by Plant
Colorado Region Data and Information by Plant
Please email our Upper Midwest or Colorado and Texas offices.
Coal combustion residuals or byproducts are generically referred to as coal ash. Fly ash, bottom ash and slag are common terms that describe different types of coal ash. Coal ash is mainly made up of rocks, minerals and other noncombustible, natural materials that are present in coal when it is mined from the earth. Coal ash contains less than 1% of trace elements, which are also found in soil and naturally exist in our environment.
Over the years, many studies have evaluated the environmental impact and safety of coal ash. The results support the classification of coal ash as a nonhazardous waste, but also confirm the importance of responsibly managing, storing, disposing and reusing coal ash.
2011 U.S. Geologic Survey report on coal ash from five U.S. power plants
AECOM report on Coal Ash Material Safety for the American Coal Ash Association
2015 U.S. Geologic Survey report Trace Elements in Coal Ash
Xcel Energy's coal fueled generating plants produced about 1.2 million tons of coal ash in 2021. We currently operate eight active coal ash facilities, including two impoundments or ponds and six landfills. In addition, we have two impoundments that we no longer use and are closing them, following the process outlined in EPA's CCR Rule. Since EPA’s CCR Rule was adopted, we have removed the coal ash from and closed 15 impoundments where we continue to monitor groundwater following EPA’s closure process.
Each coal-fueled plant is unique in the amount and type of ash it produces and how the ash is reused or disposed. More than half of our coal operations are located in arid regions where groundwater is scarce or at a greater depth — a favorable geologic condition that minimizes the possibility of environmental impacts.
About 70% of the coal ash from our operations is permanently disposed in landfills in a dry form. The Sherburne County (Sherco) Generating Plant is our only plant with an impoundment that stores wet coal ash. Coal ash from the plant is sluiced to this 100-acre facility, which was designed with state-of-the art features for managing water and protecting the environment. When the impoundment is full, it will be capped with an engineered, protective cover system, and a special collection system will continue to dry the pond after it is closed. EPA inspected the pond in 2009 during a nation-wide review and found that it meets stringent safety requirements. We would expect all our coal ash storage and disposal facilities to receive similar findings because of our high standards around safety and protecting the environment.
In 2021, 17% of the coal ash produced at our plants was reused for beneficial purposes, including 100% of the coal ash produced at our Texas coal-fueled plants. Reuse offers many environmental, engineering and economic benefits, such as:
EPA and other federal agencies encourage the responsible reuse of coal ash through a framework of engineering standards, material specifications, procurement guidelines and other programs. Many uses of coal ash are further regulated by state and local governments.
Our practice is to responsibly reuse this material whenever possible and appropriate. Currently, when we sell coal ash produced at our plants to third parties, our contracts allow only encapsulated beneficial use or un-encapsulated beneficial use in quantities less than 12,400 tons in non-roadway applications. Our contracts also require that third parties responsibly manage the coal ash and follow all federal, state and local requirements.
The most common use of our coal ash is as a cement or concrete additive and for manufacturing protective coatings. Bottom ash from our plants is mainly used for construction within lined disposal facilities, as a cement or concrete additive, and for manufacturing roof shingles and sand blasting grit.
Some ash also is used in power plant air emission-control equipment. Rather than using raw material in control equipment, such as limestone, coal ash can be used as a sorbent to capture sulfur dioxide from stack emissions.
EPA Information on Beneficial Reuse (external link)
The American Coal Ash Association (external link)
The design and operation of Xcel Energy’s coal ash facilities adheres to local, state and federal standards. We also incorporate operating practices that minimize the potential for precipitation to come in contact with the ash. These include:
EPA’s CCR Rule provides two options for closing landfills and impoundments — either removing the coal ash from the facility or installing an engineered cover system or cap over the facility. Generally, our landfills will be closed with the ash in place, with the current natural or engineered liner system, and an engineered cap installed. How we close our impoundments will vary, depending on what is best for each site’s conditions.
To confirm that our design and operating practices are effective, we install wells to test groundwater and monitor performance. Regulations and individual plant permits determine the number and location of wells. State and federal requirements specify that groundwater monitoring systems include wells located up- and down-gradient of the facilities to assess the quality of groundwater entering and leaving the site, which can help in identifying sources that may influence groundwater. EPA’s CCR Rule requires well placement as close as possible to the landfill or impoundment.
EPA Information Fossil Fuel Combustion Waste (external link)
EPA Information on Coal Combustion Residuals (external link)
The U.S. Environmental Protection agency regulates the disposal of coal ash under the Coal Combustion Residuals Rule, published in April 2015. The following are documents that Xcel Energy is required to provide under the new rule, as well as additional information on our groundwater monitoring programs at individual power plants.
Black Dog CCR Rule Implementation Notice (PDF)
Sherco Plant Implementation Notice (PDF)
Arapahoe Station CCR Rule Implementation Notice (PDF)
Cherokee Station CCR Implementation Notice (PDF)
Comanche Station CCR Implementation Notice (PDF)
EPA Notification Appendix 4 Concentration Exceedances October/November 2022 (PDF)
CCR Impoundment:
Hayden Station CCR Implementation Notice (PDF)
Pawnee Station CCR Implementation Notice (PDF)
Xcel Energy retired the coal unit at Valmont Station in March 2017. While the plant no longer operates on coal, we still maintain a landfill on the property where coal ash was placed. We regularly monitor and investigate groundwater conditions around the landfill, following Environmental Protection Agency and state of Colorado requirements.
Through our monitoring on the Valmont property, we’ve detected selenium and lithium in groundwater at concentrations above groundwater protection standards. Because of this, we’ve continued to expand our monitoring network to include testing on some nearby properties to further investigate groundwater conditions in the area. There is no indication that this situation is impacting drinking water. Although groundwater protection standards for these substances are set conservatively to protect people and the environment, exceeding a groundwater protection standard doesn’t mean there is a specific or immediate risk, only that further evaluation is needed.
We are using the groundwater monitoring and modeling results to evaluate solutions and develop an action plan for preventing groundwater constituents from moving beyond the Valmont Plant property boundary in the future. We’re making every effort to implement a solution as quickly as possible. Once the best option is confirmed, we will begin designing a solution to implement after we’ve completed our analysis and collaborated with environmental and state regulators and the public.
Valmont Station CCR Implementation Notice (PDF)
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