The company has tentatively scheduled a drawdown of 15 to 20 feet to begin in early November to expose two areas of lake bottom that contain PCBs (polychlorinated biphenyls). PCB-contaminated mud would be removed where possible, and the remainder covered with gravel and other materials.
The lowered lake levels would close public boating ramps on the lake and would strand most of the 1,150 private docks around the 5,350-acre impoundment, according to Robert Brown, a spokesman for Alcoa.
"While some parts of the lake are extremely deep, the lake will essentially be closed during this time," said Brown, who explained that once the lake level drops 5 feet – estimated at several days after the drawdown begins – public boat ramps would be closed until the lake is refilled by mid- to late December.
Brown said Alcoa scheduled the drawdown for late fall to minimize the impact on recreation. He stressed that the drawdown and remediation won't take place until they're approved by regulators.
The N.C. Division of Waste Management must give its okay, although it's not clear when that would come.
"The remediation work can not start until the public comment period for the draft Sediment Remediation Plan has closed and comments have been evaluated," said Cathy Akroyd, public information officer for NCDWM. The public comment period closed August 24.
Brown noted, however, that should the schedule slip, Alcoa may postpone the drawdown until 2013.
"The schedule could be pushed back slightly, but Alcoa does not want to risk not having the lake full for the beginning of the spring recreation season or fish spawning period. If the schedule gets too tight, the work will be delayed until fall, 2013," he said.
Alcoa last drew down Badin lake by 15 to 20 feet in December 2003 to conduct a relicensing study of fish and aquatic habitat.
The remediation project came about because of stormwater discharges to Badin Lake that occurred during and before the 1970s from Alcoa's Badin Works plant, which closed in 2010. PCBs flowed into the lake from two outfalls from the plant and now sit in sediment covering 3.7 acres, according to a remediation fact sheet posted on-line by Alcoa.
One of the PCB sites is next to the boat ramp across NC 740 from the former plant; the other is several hundreds yards north near the western shoreline.
A fish-consumption advisory sign posted at the Badin boat ramp warns of elevated levels of PCBs found in some catfish and largemouth bass in Badin Lake.
Brown said the drawdowns would not affect other lakes on the Yadkin system, including High Rock, Tuckertown and Falls.