Alcoa requests permit modification

To ensure that it continues to comply with environmental regulations at the Badin Works aluminum smelter, Alcoa has submitted a request to the N.C. Department of Environment & Natural Resources to modify its National Pollutant Discharge Elimination System (NPDES) permit.

Alcoa is requesting to redirect stormwater from a small ½ acre site within the Badin Works property to another stormwater discharge outfall. With this modification, Alcoa is confident that fluoride levels in stormwater entering Badin Lake will remain below the allowable limits. No new or increased flows or fluoride levels in the stormwater discharge from Badin Works are being requested.

Fluoride is a naturally occurring chemical that is used in the aluminum manufacturing process and waste containing fluoride was previously stored on the Badin Works property. As part of the remediation process at Badin Works, Alcoa removed this waste and the underlying soil from the ½ acre site in 1994 and disposed of it an appropriate industrial landfill.

Stormwater runoff from this ½ acre site contains low levels of fluoride, but does not pose any risk to people who use Badin Lake (swimmers or fisherman) or to the wildlife or aquatic life in Badin Lake. Monitoring shows that fluoride levels are typically within the limits set by US Environmental Protection Agency for drinking water.

As part of its environmental responsibility, Alcoa is continually looking at ways to reduce fluoride levels. During the past two years, Alcoa has spent more than $180,000 to identify and reduce the amount of fluoride in stormwater. These efforts have included a variety of steps, including but not limited to:

• Simulating rain events and collecting soil, sediment and water samples to better determine the source of fluoride.

• Minimizing contact between stormwater and surface soils by installing new liners in drainage channels, roadways and parking areas, then covering those areas with stone.

Background on Fluoride

Fluorides are naturally occurring compounds that are often added to drinking water supplies and a variety of dental products, including toothpaste and mouth rinses, to help prevent dental cavities. Small amounts of fluoride are beneficial. Over time, ingestion of very high levels of fluoride in drinking water may cause brittle bones in children and adults and mottled teeth in children.

For the prevention of dental decay, the Public Health Service has recommended since 1962 that public water supplies contain between 0.7 and 1.2 milligrams of fluoride per liter of drinking water. The Environmental Protection Agency has set a maximum amount of fluoride allowable in drinking water of 4.0 milligrams per liter of water.

The NPDES permit places limits on fluoride levels coming from a portion of the Badin Works plant to 1.8 milligrams per liter, even though these discharges are located far from drinking water withdrawals.