RALEIGH – The Division of Waste Management has entered into an administrative agreement with Alcoa Inc. that requires the company to install a cap composed of sand, gravel and rock over two areas on the bottom of Badin Lake where sediment has been contaminated by low levels of polychlorinated biphenyls (PCBs) originating from the company’s Badin operations.
The Division of Waste Management’s approval of the sediment remediation project this week includes a condition that the state can require additional remedial work if project goals are not achieved to DENR’s satisfaction or if DENR determines that additional remediation measures are necessary.
“This project will move forward with full understanding that it does not in any way limit our authority to require Alcoa to do additional assessment or remediation if new information indicates that is necessary to address contamination associated with the Badin plant’s operations,” said DWM Director Dexter Matthews.
For a number of years, PCB-contaminated stormwater runoff from the site of Alcoa’s now idle aluminum smelting plant entered the lake through two stormwater outfalls. DWM believes that the PCBs in the stormwater came from leaks and spills of PCB-containing fluids from electrical and hydraulic equipment, as well as releases from old waste disposal areas. Use of PCBs on the Alcoa site ceased in the 1970s and waste disposal areas on the plant site that were likely sources of the PCB contamination have been remediated.
The cap will isolate the PCB-containing sediments by preventing any re-suspension into the waters of the lake and thus remove the potential for PCB exposure to the lake’s aquatic life.
The project will involve lowering the water level in Badin Lake by approximately 15 feet, excavating the maximum amount of contaminated sediment possible, and placing the cap to cover any remaining contaminated sediments that cannot be removed and hold them in place.
Capping will take place during the upcoming fall and winter months to avoid adverse impacts on the fish spawning season. The project and a subsequent return to normal lake water levels are estimated to be completed within five weeks from the start of project work, and are not expected to impact spring and summer recreational boating and fishing activities.
The project is being conducted under the authority of North Carolina’s Inactive sites and Hazardous Substance Response Act and will be overseen by the division’s technical staff. The final administrative agreement can be found online at http://portal.ncdenr.org/web/wm/alcoa-badin.
(The preceding is a press release from DENR, issued September 20, 2012.)