The spill began sometime between midnight and 1 a.m. Eastern Standard Time on December 22, 2008, when the dike surrounding the ash containment dewatering pond broke. The breach occurred at the northwest corner of the dewatering pond, overlooking the Swan Pond Creek spillway. The spill consisted of an initial large wave which lasted for approximately one minute, followed by a series of smaller consecutive waves of breaking away and sliding that occurred over a period of approximately one hour.
