"Impervious surface" means a non-vegetated area that either prevents or retards the entry of water into the soil mantle as compared to infiltration under natural conditions prior to development. A non-vegetated area which causes water to run off the surface in greater quantities or at an increased rate of flow from the flow that was present under natural conditions, prior to development. Common impervious surfaces include, but are not limited to, roofs, walkways, patios, driveways, parking lots, storage areas, concrete or asphalt paving, graveled areas and roads, packed earthen materials, surfaces covered by oil, macadam, asphalt treated base material (ATB), bituminous surface treatment (BST), chip seal, seal coat or emulsified asphalt and cutback asphalt cement, and other surfaces which similarly impede the natural infiltration of stormwater. Open, uncovered retention and detention facilities shall not be considered impervious surfaces for purposes of determining whether the thresholds for applying minimum stormwater management requirements are exceeded pursuant to chapter 30.63A SCC. However, open, uncovered retention and detention facilities shall be considered impervious surfaces for purposes of runoff modeling. (Added by Amended Ord. 02-064, Dec. 9, 2002, Eff date Feb. 1, 2003; Amended by Amended Ord. 10-026, June 9, 2010, Eff date Sept. 30, 2010; Amended by Ord. 15-103, Jan. 11, 2016, Eff date Jan. 22, 2016).