River gauges show the Waccamaw River did not quite reach the 22-foot flood levels predicted earlier this week in Conway.
On Wednesday it appeared to finally crest at 21.17 feet after more than a week of rising. While that may not seem like much difference, it was just enough to keep the river from overtopping a coal ash pond outside town.
“That leaves us about a foot between the top of the river and the top of the AquaDam that we’ve got around our second ash pond,” Santee Cooper spokeswoman Mollie Gore said. She noted the temporary AquaDam that crews installed on top of the protective dikes ahead of the flooding had almost certainly prevented water from flowing into the pond.
Gore said the dams will remain for another week at least as floodwaters slowly go down again. Crews will also need to pump out water in the ponds.
Santee Cooper had been nervous the water could breach into its ponds, which contain potentially hazardous byproducts from the coal power process, such as arsenic and lead. The Grainger plant which once operated at the site was shuttered in 2013, but the utility has worked to remove more than 1.2 million tons of ash left behind. About 200,000 tons still remained when Hurricane Florence came ashore.
The utility initially took steps ahead of the storm to safeguard its ponds along the Waccamaw. The precautions included filling the ponds to stabilize the pressure on the dikes and placing containment booms. Santee Cooper later added the AquaDam atop the dam of its second pond to safeguard it for floods up to 22 feet.
Floodwaters did overtop the first pond, but Gore said Pond 1 was mostly empty from previous cleanup work and no significant contamination is expected.