EPA Tells Tennessee it Must Limit Toxic Heavy Metals in Coal Ash Pollutions Discharges

August 31, 2011


This August the U.S. EPA sent letters to Tennessee, telling the state it must do better before issuing proposed Clean Water Act permits for TVA’s Kingston and Gallatin coal plants. These permits, known as National Pollutant Discharge Elimination System (NPDES) permits, are required for discharges of pollutants to surface water. Kingston, Gallatin, and other coal plants use water to transport and store fly ash, bottom ash, and other wastes. This process results in water contaminated with arsenic, selenium, and other toxic ‘heavy metals’ that stay partially suspended in the liquid. Coal plants routinely discharge the contaminated water into nearby rivers and streams, because Tennessee’s NPDES permits do not currently restrict discharges of toxic metals.

When Congress passed the Clean Water Act, it established the goal of eliminating all discharges of water pollution into our rivers and streams. To accomplish this, the Act requires NPDES permits to include “Technology-Based Effluent Limits” for all known pollutants in a given discharge; as technology and knowledge advance, permits should become more protective and pollution should decrease. Put simply, coal plants are required to achieve the best pollution reductions that available technology can provide.

Some of these limits are set in industry-specific “Effluent Limit Guidelines;” others are set on a case-by-case basis when a state agency uses its Best Professional Judgment to determine what technology is available to control a pollutant. EPA set guidelines for the steam electric industry in 1982 and included limits for pH, oil & grease, and total suspended solids, but not for heavy metals. Since that time, many utilities and state agencies have asserted that they are not required to set any limits beyond those in the Effluent Limit Guidelines.

EPA’s recent letters finally refute that claim, however; the Clean Water Act requires Technology-Based Limits on heavy metals, and these limits must be set on a case-by-case basis:

“[T]he record for the 1982 Effluent Limit Guidelines indicates that best available technology . . . was not established for fly ash or bottom ash transport water in the final 1982 rule. These wastewaters discharge from coal ash impoundments. Thus, best available technology-based limits would currently need to be established through best professional judgment for discharges from coal ash impoundments” (acronyms expanded).

The letters direct the Tennessee permitting agency to evaluate the costs for TVA to install, “at a minimum, chemical precipitation and/or biological treatment for the . . . discharges in order to reduce effluent discharge of metals.” In other words, the Clean Water Act requires TVA to treat this waste stream with the best available technology, and Tennessee must stop letting polluters off the hook.