Santee Cooper anticipates rising Waccamaw could overtop ash pond 2
CONWAY, S.C. – Based on NOAA river projections, Santee Cooper expects the Waccamaw River could begin overtopping Grainger Ash Pond 2 sometime tomorrow afternoon, Sept. 25. Overtopping does not mean that the dike will breach or that ash will be released, and preventative work Santee Cooper has done will mitigate any potential impacts. That work includes:
- Pumping water from the Waccamaw into both ash ponds, so that water in the ponds will balance pressure on the earthen dikes from the rising river. Experts believe this action means the structural integrity of the submerged dikes likely will not be compromised.
- Staging heavy equipment, sand and other materials in place for use as needed. We also have several hundred tons of gravel already bagged in 1.5-ton sacks, which a heavy-lift helicopter can place if needed.
- Installing a portable, water-inflated AquaDam around the entire 6,000-foot perimeter of Pond 2, adding at least 30 inches of protection to the top of the dike.
- Adding a layer of 30-inch-high silt fencing around the Pond 2 dike perimeter, intended to filter water moving out of the pond.
- Placing approximately 11,000 feet of floating environmental containment boom throughout the site. The boom is intended as a barrier to contain particles if they are dislodged and rise to the surface.
- Preparing to assess impacts of any potential discharge, by collecting baseline surface water and sediment samples and conducting daily upstream and downstream river and sediment sampling. Results of the sampling will indicate whether ash leaves the ponds and guide additional mitigation if it is needed.
The Waccamaw has eclipsed its record flood level set in 2016 and is still rising. The lowest part of the AquaDam atop Pond 2 is 21.5 feet gage height, and NOAA is forecasting a river crest of 22 feet gage height will occur midafternoon Wednesday.
Santee Cooper is working with DHEC, downstream water users, the Waccamaw Riverkeeper and other stakeholders as this situation develops.
Santee Cooper began excavating the ash ponds in 2014, has already removed about 1.4 million tons and was on track to finish that effort within a few months. Approximately 200,000 tons of ash remains in Pond 2 and is below dike level in the section farthest from the river.