In undeveloped areas, rainwater is unrestricted and may be absorbed directly into the ground on which it falls. When an area is developed, buildings and parking areas overcome the natural absorption area where the rain would normally be infiltrated back into the ground. These impervious structures offset the typical absorption pattern. As a result, when the rain is not allowed to penetrate it begins to build up, may cause ponding or flooding and/or begins to flow to another location. Road flooding: accidents, washouts, driver delays. Building & property flooding: structural & property damage, sewer backup, foundation settlement, devalued properties. Environmental damage. Utility service interruptions. Increased clean-up costs, health hazards, personal inconvenience, increased insurance costs.