Impervious surface means a surface that has been covered with a layer of material so that it is highly resistant to infiltration by water.
Contaminate means the addition of sediment, any other pollutant or waste, or any illicit or prohibited discharge.
Surface impoundment or "impoundment" means a facility or part of a facility which is a natural topographic depression, man-made excavation, or diked area formed primarily of earthen materials (although it may be lined with man-made materials), which 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.
Building means any structure used or intended for supporting or sheltering any use or occupancy.