Coal Ash Re-Use and Recycling
About 40% of the coal ash produced every year is “recycled” in what EPA and industry call “beneficial re-use.” However, valid concerns exist around the safety of re-using coal ash, as it poses another route for human and environmental exposure. Coal ash is commonly reused in a number of ways. For example, it is used as structural fill or fill for abandoned mines; as a top layer on unpaved roads; as an ingredient in concrete, wallboard, and in school running tracks; as an agricultural soil additive; and as “cinders” to be spread on snowy roads.
Every year, about 11.5 million tons of coal ash is placed in structural fills such as highway embankments or building foundations. Because this re-use is subject to little or no regulation, some structural fills may be little more than dumpsites in disguise. There are no current federal standards regulating how coal ash is re-used. For example, a 60 Minutes segment from August 15, 2010 highlighted the consequences from using toxic coal ash as a “fill” to build up part of a golf course.
Mine filling is another re-use of particular concern. In this form of re-use, coal ash is dumped directly into abandoned mines and quarries, and typically is in direct contact with the water table, which has resulted in significant contamination.
Some re-use is less controversial. For example, ash is also sometimes used making materials such as bowling balls, concrete and bricks. These uses fully “encapsulate” coal ash, in theory locking the ash and its toxic contaminants away. Encapsulated re-uses also reduce the need for extraction of virgin natural resources – coal ash can replace a significant amount of high-carbon-footprint materials like Portland Cement. EPA has designed some of its proposed coal ash rules to account for this and actually incentivize additional reasonable re-use. However, some warn that EPA’s assessment of risk for coal ash in building materials may be inaccurate that encapsulated uses of coal ash could pose risks to human health.
Update: In early February 2014, EPA, using a newly developed methodology, determined coal ash and other coal combustion residuals are safe to use in concrete as a substitute for portland cement, and the use of flue gas desulfurization gypsum as a substitute for mined gypsum in wallboard. EPA’s evaluation concluded that the beneficial use of encapsulated CCRs in concrete and wallboard is appropriate because they are comparable to virgin materials or below the agency’s health and environmental benchmarks.