An impervious area is any area within a parcel which prevents or significantly impedes the infiltration of stormwater into the soil. Examples of impervious surfaces include: Parking lots, Roofs, Driveways, Patios, Sidewalks, Swimming Pools, and Gravel and stone areas. As pervious areas (natural soil) become "paved", increased amounts of stormwater are generated, placing an increased demand on the stormwater system.