"Surface impoundment" shall mean a facility or part of a facility that is a natural topographic depression, human-made excavation, or diked area formed primarily of earthen materials, or lined with synthetic materials, that is designed to hold an accumulation of liquid wastes or wastes containing free liquids, and which is not an injection well. Examples of surface impoundments are holding, storage, settling, and aeration pits, ponds, and lagoons.
132 Neb. Admin. Code, ch. 1, § 132