Waste impoundment, or impoundment, definition
Waste impoundment, or impoundment, means a facility or part of a facility that is a natural topographic depression, excavation, pit, pond, lagoon, trench or diked area. An impoundment, which may be lined with earthen material or synthetic material, is designed for storage, treatment or final disposal of solid waste. Examples of impoundments are holding, storage, settling and aeration pits, ponds and lagoons.