In City of Bowman v. Gunnells, 243 Ga. 809, 811 (2) (256 S.E.2d 782) (1979), the Court established guidelines for determining whether a municipality will be liable for creating or maintaining a nuisance: the defect or degree of misfeasance must exceed mere negligence (as distinguished from a single act); the act complained of must be of some duration and the maintenance of the act or defect must be continuous or regularly repetitious; and there must be a failure of municipal action within a reasonable time after knowledge of the defect or dangerous condition.