Stormwater Management

July 02, 2021 (Reston, Virginia)

When land is undisturbed, rain and snow melt and flow into waterways, are filtered by earth or absorbed by vegetation. Any time you add roads and buildings, which have impermeable surfaces, to an area of undeveloped land, it reduces natural absorption in the areas they are built and can increase the speed at which water runs off the property into streams and storm sewers. As areas become more densely developed, it is important to manage stormwater, because without appropriate management water can build up where it is unwanted or overrun controls and waterways. It’s a problem that’s compounded by the increase in severe storms driven by changing climate.

Local counties and municipalities are responding to the increased urgency for improved stormwater management by imposing more substantial requirements on developers and builders. There are limits on the amount of impermeable surface that can be included on a lot or community (in the form of roofs, lead walks, patios, driveways, and the like), and often communities or lots require stormwater management in the form of ponds, rain gardens or rain planters.

A stormwater management pond is typically built to serve an entire community. It effectively is a large gravel pit, which is eventually covered over with grass, that provides an underground area for stormwater to gather and allow it to filter more slowly into the ground water or waterways. In dry weather, some stormwater management ponds look like grassland or low meadows with wildflowers. A rain garden is a smaller version of the same concept, usually added to a single lot as an underground repository for rainwater or snowmelt.

These management systems can make a big impact on reducing the speed at which water runs off, thereby “spreading it out” so it flows more slowly into waterways, which can then handle the water as they would naturally.