What is Impervious Surface?
The Beckley Stormwater Ordinance defines “Impervious area” as land area covered by buildings, pavement, gravel or other material that significantly inhibits stormwater from penetrating the soil. Because of its composition or compacted nature, impervious areas impede or prevent natural infiltration of water, thus these areas cause significant increased volumes of runoff from precipitation and quicker peak flows of discharge, which contributes to downstream drainage problems and urban flooding.
Impervious areas also accumulate large quantities of solids, oil and greases, polycyclic aromatic hydrocarbons, bacteria and metals such as lead and zinc which are washed off of these surfaces and become polluntants in local waterways. Research shows the amount of impervious areas within watersheds are the most important determinant of waterbody health/degradation.
Across the United States, stormwater utility’s use impervious area based fee structures, because they equitably distribute the costs of operating, maintaining and providing environmental improvement programs among property owners that contribute the greatest to the water quantity and quality problems that large impervious areas generate.
Examples of impervious surfaces
- Tennis Court, Roof & Parking lot
- Gravel driveway after rain
Stormwater runoff effects from impervious surfaces
For more information about Stormwater and its effects please visit the follow Web pages:
Stormwater Utility Fee Calculation Methods
Geographic Information Systems (GIS) & Remote Sensing