Storm Water Management
Have you ever seen certain areas or property developments that flood or have standing water every time it rains? This occurs when water doesn’t have a way to infiltrate the ground. Water runoff needs a place to go to prevent flooding, erosion, pollution and other environmental issues. Control and treatment of water runoff is called storm water management. There are a variety of ways to manage storm water.
You might be asking why this information is important to you. Well, storm water management is required on most development sites. If you’re planning to construct a new building or even renovate or add on to existing infrastructure, there is a good chance you will be required to install some form of storm water management. When property is developed, land is covered with impervious structures, such as buildings and parking lots which results in less land area for water infiltration. If water cannot infiltrate into the earth, flooding can occur. Storm water management provides site grading to direct storm water to specific locations such as detention or retention ponds or basins where it can be stored until it can slowly infiltrate into the earth or outlet at a specified rate to control flooding. Storm water basins also function as a water treatment facility. Storm water enters the basins and as it infiltrates or outlets, pollutants and sediment settle out of the water improving the quality of the water before it enters rivers and streams.
Detention and retention basins improve water quality and reduce flooding, but they can also take up valuable land area. Calculations for sizing storm water basins can vary, however it is conceivable that a basin could be 50% of a site. Owners must evaluate the conditions of their site to determine if basin size requirements and the amount of land they require are a cost/benefit in property development. If over 50% of a parcel of land is used for storm water management that leaves less land area for income producing area such as, buildings, parking, landscaping and other governmental requirements associated with land development.
Alternatives to standard detention and retention ponds:
- Underground Detention: A system of underground perforated pipes that hold storm water and control the rate of release. Underground systems can be costly.
- Raingardens or Bio-swales: Mini pond depressions around the site, potentially in parking lot islands or lawn extensions, which are designed with soils that infiltrate water and are planted with native plant species that can tolerate being submerged in water and drought conditions. Raingardens or Bio-swales may not provide enough treatment volume.
- Stormceptors: Similar to an underground cistern that uses cylindrical force to separate pollutants out of storm water. Stormceptors are not a substitute for volume, but work best for treatments when land area is limited.
- Green Roofs: Can be a good alternative if space is limited. See our article on Green Roofs for more information.
Storm water management is something to consider early on in the development process due to its space and site planning implications. Some jurisdictions are willing to permit flexibility in design and alternative designs. Some jurisdictions also give credits or incentives for using alternative “green” storm water management alternatives.
In our experience, storm water management can delay projects and can become a costly component. You can reduce your wait time to begin construction by working with a team of professionals and your local government entity early on in your planning for your new construction or renovation project.