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Coal Ash Management

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 62% 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 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.

Find our CCR Rule Compliance Data and Information and learn more about our groundwater monitoring programs at individual power plants.

Upper Midwest Region Data and Information by Plant

Colorado Region Data and Information by Plant

Have specific questions?

Please email our Upper Midwest or Colorado and Texas offices.

Coal ash composition

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.

Learn more about coal ash and read some of the studies

EPA information on 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

Production, storage and disposal

Our generating plants consumed 14.8 million tons of coal in 2020, producing about one million tons of coal ash. Xcel Energy currently operates 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 ponds 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 a pond that stores wet coal ash. Coal ash from the plant is sluiced to this 100-acre pond, which was designed with state-of-the art features for managing water and protecting the environment. When this pond 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.

Beneficial Reuse

In 2020, 16% 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)

Environmental Management

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 ponds — 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 ponds 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 pond. 

Additional Resources

EPA Information Fossil Fuel Combustion Waste (external link)

EPA Information on Coal Combustion Residuals (external link)

CCR Rule Compliance Data and Information

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.

CCR Rule Compliance Data and Information - Upper Midwest

Sherco Plant CCR Operating Record

Sherco Plant Implementation Notice (PDF)

Common:

Operating
Annual Emergency Action Plan Meeting
Fugitive Dust

Bottom Ash Pond:

Design
Location Restrictions Report
Liner Assessment
Marker
Hazard Potential
Emergency Action Plan
History of Construction
Structural Stability
Safety Factor
Operating
Inflow Flood Control Plan
Inspections
Groundwater Monitoring:
Closure and Post Closure
Closure Plan
Post Closure Plan

Scrubber Solids Pond #3:

Design
Location Restrictions Report 
Liner Assessment
Marker
Hazard Potential
Emergency Action Plan
History of Construction
Structural Stability
Safety Factor
Operating
Inflow Flood Control Plan
Inspections
Groundwater Monitoring
Closure and Post Closure
Closure Plan
Post Closure Plan

Dry Ash Disposal Landfill:

Operating
Unstable Area Report
Run-On and Run-Off Plans
Inspections
Groundwater Monitoring
Closure and Post Closure
Closure Plan
Post Closure Plan

Bottom Ash Pond #2

Design
Location Restrictions Report
Liner Assessment
Marker

 

Hazard Potential
Emergency Action Plan
History of Construction
Structural Stability
Safety Factor
Operating
Inflow Flood Control Plan
Inspections
Groundwater Monitoring
Closure and Post Closure
Closure Plan
Post Closure Plan

CCR Rule Compliance Data and Information - Colorado

Arapahoe Station CCR Operating Record

Arapahoe Station CCR Rule Implementation Notice (PDF)

CCR Impoundment:

Closure and Post-Closure

Cherokee Station CCR Operating Record

Cherokee Station CCR Implementation Notice (PDF)

CCR Impoundment:

Design Criteria
Operating Criteria
Groundwater Monitoring
Closure and Post Closure

Comanche Station CCR Operating Record

Comanche Station CCR Implementation Notice (PDF)

Common:

Operating Criteria
Groundwater Monitoring

CCR Landfill:

Design Criteria
Operating Criteria
Closure and Post Closure

CCR Impoundment:

Design Criteria
Operating Criteria
Closure and Post Closure

Hayden Station CCR Operating Record

Hayden Station CCR Implementation Notice (PDF)

CCR Landfill:

Design Criteria
Operating Criteria
Groundwater Monitoring
Closure and Post Closure

Pawnee Station CCR Operating Record

Pawnee Station CCR Implementation Notice (PDF)

Common:

Operating Criteria

CCR Landfill:

Design Criteria
Operating Criteria
Groundwater Monitoring
Closure and Post Closure

CCR Impoundment:

Groundwater Monitoring
Closure and Post-Closure

Groundwater Monitoring at Valmont Station

In March 2017, we retired the coal unit at Valmont Station. While the plant no longer operates, we still maintain a landfill on the property where coal ash was disposed. Through our ongoing environmental monitoring of the landfill, we expanded our groundwater monitoring network to install new wells at the landfill and also on property owned by the City of Boulder, adjacent to the Valmont property.

Results from the new monitoring wells show levels of selenium and lithium above groundwater protection standards beneath the adjacent City of Boulder property. We are now working to evaluate groundwater conditions at seven private properties northeast of Valmont Station and expect to have initial results in early 2022.

We’re using the groundwater monitoring and model results to evaluate solutions and develop an action plan for preventing groundwater constituents from continuing to migrate 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 working on design.

We want to implement the solution at the plant in 2023, after we’ve completed our analysis and collaborated with environmental and state regulators and the public.

Valmont Station CCR Operating Record

Valmont Station CCR Implementation Notice (PDF)

Common:

Operating Criteria
Groundwater Monitoring

CCR Landfill:

Design Criteria
Operating Criteria
Closure and Post Closure

CCR Impoundments:

Design Criteria
Operating Criteria
Closure and Post-Closure

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