State scientists determined that excavation was the only acceptable option because Duke Energy's coal ash sits deep in the groundwater, and if left in unlined, leaking lagoons as Duke proposes, it would continue to pollute indefinitely. According to Duke Energy's own analyses, it has the ability to remove the wet ash from unlined pits to dry, lined landfills on-site at each of the six sites in question. Duke Energy is required to clean up seven other coal ash sites in North Carolina by court order and an eighth coal ash site by a settlement agreement with the Southern Environmental Law Center, Waterkeeper Alliance, and Yadkin Riverkeeper.