Stormwater Management and Chevy Chase Lake
One of the concerns we’ve heard from the community is the impact redevelopment may have on Coquelin Run (roughly this is the tributary that runs between 8101 Connecticut Avenue and Chevy Chase Lake Drive). We felt it would be beneficial to define stormwater management and how redevelopment of Chevy Chase Lake will actually improve stormwater management. We’ll do this in a two part series. The first segment will cover the basics of stormwater management and the second will focus specifically on its application to Chevy Chase Lake.
First let’s start with some definitions. The U.S. Environmental Protection Agency defines stormwater as runoff that is “generated when precipitation from rain and snowmelt events flows over land or impervious surfaces and does not percolate into the ground. As the runoff flows over the land or impervious surfaces (paved streets, parking lots, and building rooftops), it accumulates debris, chemicals, sediment or other pollutants that could adversely affect water quality if the runoff is discharged untreated.” Some refer to this very generally as drainage, but there is a very important distinction to make between stormwater and sewer water. They are managed in very different ways. Sewer water (the stuff you flush, put down your household drains, etc.) is captured by the county sanitary sewer system and flow directly to a treatment works facility. They do not flow into Coquelin Run. What impacts Coguelin Run is stormwater.
One of the biggest sources of stormwater comes from single family residential developments. When people treat their lawns with fertilizers and pesticides or wash their cars those chemicals run directly into stormwater drains and into nearby watersheds. Since this type of development is not being proposed in Chevy Chase Lake let’s focus on other sources of stormwater runoff. Often commercial developments feature large impervious surface parking lots. We have some of these currently at Chevy Chase Lake. When it rains pollutants wash into stormwater drains and into the watershed. Rooftops are also another source of stormwater runoff that ends up in Coquelin Run. Thankfully, stormwater management techniques have improved greatly over the last decade and many best practices are now common and in some cases mandatory. As part of the new Commercial-Residential Zone (CR Zone), developers actually get credit for some of these best practices, such as green roofs. Other construction techniques, such as permeable pavement or curbside gardens also have significant impacts. Even providing structured parking instead of large surface area lots opens up options for better stormwater management.
As we mentioned before, the primary watershed in Chevy Chase Lake is Coquelin Run, with is a tributary of lower Rock Creek. Rock Creek eventually feeds into the Potomac, which in turn drains into the Chesapeake Bay. Montgomery County has deemed the condition of Coquelin Run as “poor” in the last assessment in 2002. This is because the area “was largely developed during the time when control of stormwater runoff was not required.” Redevelopment of Chevy Chase Lake with current best practices could make a significant impact on the health of Coquelin Run. We’ll talk about some of those specific possibilities and opportunities in the second part of this post. For more information about stormwater management, the National Resources Defense Council has a very informative section on its website that you can access by clicking here. The Montgomery County Department of Environmental Protection website also has valuable information available by clicking here.
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