Stormwater management is a critical aspect of every construction project. As land development continues on multiple properties across a State County, an important question that civil engineers must consider is how to best manage stormwater runoff for each project.
Homes built today are much larger than homes built 50 years ago. With the larger impervious area footprint of these homes, there is an increased amount of water runoff and an equal decrease in landscaped/natural yard space from what existed prior. With less natural yard space on each property owner’s lot, this extra water runoff has nowhere to go but runoff into neighboring properties and into the public street right of way, which carries pollutants into our waterways.
As the water runs off your property, it can pick up pollutants along the way such as yard fertilizer, oil drips in a driveway or street, and sediment. From there, your surface water runoff continues downhill, along with runoff from all of your neighbor’s properties in your watershed, until it reaches a public storm sewer system which conveys the water more efficiently to local outfall point. This outfall point is typically a neighborhood drainage ditch and/or a perennial stream, which flows further to a tributary, then a river. In the case of Northern Virginia, most of the area’s counties (Fairfax, Loudoun, and Arlington) eventually flow into the Potomac River and ultimately the Chesapeake Bay. To protect water resources, communities can implement stormwater pollution prevention plans.
Why Is Stormwater Management Important?
There are two major concerns for Stormwater Runoff with increased land development and bigger homes; quality and quantity of water. As mentioned above, the water runoff picks up pollutants along the way and transports these pollutants into our local streams, rivers and bay. The poor quality of water runoff will result in a degraded environment downstream. An increased quantity of water runoff causes more erosion to local streams which causes further damage to the environment.
One may think that their individual lot consisting of a single home being built isn’t that much of an increase in stormwater runoff. However, adding that home to thousands of other homes being built in the same county, the negative effects begin increasing exponentially, contributing significantly to the overall environmental problem. Every landowner has a right to build on their property; however, they do not have a right to further damage the local environment with increased stormwater runoff.
Stormwater Pollution Prevention Plans
In an effort to protect the local environment, the Commonwealth of Virginia enacted the Chesapeake Bay Preservation Act (Chesapeake Bay Preservation Act | Virginia DEQ). The Chesapeake Bay Act is controlled through the Department of Environmental Quality (DEQ) on the State level, but has issued general discharge permits to the local level so that local county governments can regulate stormwater runoff through Land Disturbance Permits.
Each county in Northern Virginia has its own Stormwater Management Requirements to uphold in order to fulfill its duties in protecting the Chesapeake Bay:
- City of Alexandria Stormwater Management Program
- Loudoun County Stormwater Management Program
- Fairfax County Stormwater Management Program
- Arlington County Stormwater Management Program
Sustainable Land Development
Most counties in Northern Virginia, primarily Fairfax County and Arlington County, have a shared goal of sustainable land development. These counties require a “net-zero” impact on the environment in terms of trees and stormwater. Any land development project over 2,500 square feet in land disturbance triggers these requirements, making them necessary to achieve in order to obtain a land disturbance permit. When developing a project over this threshold, the “net-zero” impact for post-development stormwater runoff needs to be equal to or less than pre-development conditions. With an increase in impervious area, the increased amount of stormwater needs to be detained, treated on-site, and released at a rate equal to or less than pre-developed conditions. Our Civil Engineers are experts in developing Site Plans to address these requirements for plan and permit approval.
Homeowners and developers may think they are subsidizing or bearing the burden of these stormwater regulations, compared to homeowners who do not develop their property, but that is a common misconception. Each landowner is responsible for the net increase in stormwater runoff that their project directly produces. Choosing to maximize the buildable area of your property will result in more stormwater management controls required to offset the net increase in stormwater runoff. Choosing to build a more modest size home that does not have an increase in impervious area, or only a minimal increase in impervious area from what was there before, will not have as much of a cost in stormwater controls as a larger home project. Therefore, the stormwater requirements are proportional to the net increase of impervious area.
Stormwater Management for Homeowners
Examples of stormwater management (SWM) controls are planter boxes, rainwater detention tanks, and permeable pavers. The larger the house, the more of these SWM controls our Civil Engineers will need to design to meet State and County level requirements to obtain plan and permit approval for your project. Therefore, if you want to maximize the amount of buildable area allowed by zoning, you will need to be prepared for the costs and impacts associated with having to design for the increased amount of stormwater.
Our Civil Engineers are experienced in working with homeowners and developers in maximizing the buildable area of their homes. During the detailed design phase, our Civil Engineers can provide options for stormwater management in Northern Virginia. Sometimes the options for more modest size home builds can be as simple as providing a permeable paver driveway or 1 planter box. Larger home builds can require a combination of options such as a permeable paver driveway, 3-4 planter boxes and 1-2 above-ground rainwater detention tanks.
Our profession is Land Development and we believe in the right to develop property. However, we also believe in sustainable land development so that we can all continue to develop land responsibly for years to come and protect the environment. It is important that our clients also understand this responsibility when building a larger home.
If you are planning to build a new addition or home in Northern Virginia or Washington, DC, please contact us for a quote on your next Land Development project.