Need for Stormwater Management
Stormwater runoff is rainfall or snowmelt that flows from saturated permeable surfaces like roofs and paved driveways, sidewalks, parking lots and streets. Stormwater runoff creates drainage and flooding problems and picks up pollutants such as oils, grease, fertilizers, pesticides, litter, and metal. This runoff is then collected and conveyed by ditches, culverts, intakes, catch basins, and storm sewers that discharge directly into creeks, rivers, streams, and lakes without being treated to remove the pollutants. The contaminants in stormwater negatively impact the quality of our local streams and lakes.
New federal laws regulating stormwater runoff require the City of Urbandale to develop and implement a comprehensive stormwater quality management program to protect and improve water quality.
An impervious surface is any surface area that does not readily absorb water. Because water cannot be absorbed adequately, it runs off these surfaces and must be managed through well planned, constructed and maintained stormwater facilities to prevent flooding and pollution of the receiving waters.
The stormwater management fee is based on the amount of total impervious surface on your property. This amount of impervious surface is a good gauge of how much your property is contributing to the overall need for stormwater management facilities in our community.
Gravel is considered an impervious surface. It is difficult for water to soak into a packed gravel surface. Once gravel is compacted, surface water runs off of it much like a paved surface. The gravel may slow the flow of water from an area, but nearly the same amount of runoff will flow from under the gravel as if the gravel was not there. Many flat roofs are covered with gravel, but they still shed the rainwater that falls on them. In addition, if cars or heavy equipment are traveling on gravel surfaces, the runoff typically carries pollutants like metals or petroleum into our waterways.