Article VII Definitions

Impervious Surface.  A non-vegetated surface area that either prevents or retards the entry of water into the soil mantle as under natural conditions prior to development.  A non-vegetated surface area which causes water to run off the surface in greater quantities or at an increased rate of flow from the flow present under natural conditions prior to development. Common impervious surfaces include, but are not limited to, roof tops, walkways, patios, driveways, parking lots or storage areas, concrete or asphalt paving , gravel roads, packed earthen materials, and oiled, macadam or other surfaces which similarly impede the natural infiltration of stormwater.  Open, uncovered retention/detention facilities shall not be considered as impervious surfaces for purposes of determining whether the thresholds for application of minimum requirements are exceeded.  Open, uncovered retention/detention facilities shall be considered impervious surfaces for the purposes of runoff modeling.

Effective on: 4/16/2011