Recent test results in Mooresville indicated that the town’s growing coal ash sinkhole has not further contaminated municipal drinking water. The town initially conducted sampling after North Carolina Department of Environmental Quality inspectors found coal ash in the nearby streambed, a tributary of Lake Norman, in 2020.
The sinkhole formed outside of the local business Tire Masters, located off N.C. Highway 150, heading towards Lake Norman, when an underground pipe failed under the parking lot. The sinkhole first appeared in 2018 as a depression in the pavement, but Ryan Rase, assistant town manager of Mooresville, says the town was not aware until 2020.
The hole has continued to widen as rain erodes the surrounding concrete. Coal ash had been used as a filler when the property was regraded for construction — a regular and largely unregulated practice in the 1980s and ‘90s. As rainwater enters the sinkhole, it washes chemical pollutants downstream.
The lighter, powdery coal ash used in structural fills contains many highly toxic pollutants and heavy metals such as mercury, arsenic, copper and chromium.
The town sampled groundwater from a stream immediately south of the site and the location where the stream discharges into Lake Norman. Test results for heavy metals and radioactive materials, both associated with coal ash pollution, did not exceed water quality standards.
Rase said most people in the area rely on municipal drinking water supplied from Lake Norman. The town is developing a plan to clean up the site, which they’ll submit to the DEQ.
“They’re going to want to see that you’ve contacted some professionals, whether it be geologists or engineers, that know how to work around different situations like we’re dealing with the sinkhole,” Rase said.
The town of Mooresville has contracted a Charlotte-based structural engineering firm to make sure that the building doesn’t collapse into the hole during repairs. The town is also working with Charlotte-based engineering consultants to assess potential human and environmental threats and pursue federal assistance through the Environmental Protection Agency’s Brownfields program.
Rase said the town hopes to begin repairs within the next “90 to 120 days,” which will include partial excavation of the structural fill, but assured residents that the town’s drinking water remains safe.
“The town of Mooresville is required — just like any other municipality — to test our drinking water,” said Rase. “We have met and exceeded all of the parameters and requirements per our potable drinking water permit.”
