DC’s Stormwater Management Rule
Washington, DC is calling on its citizens to help decrease the amount of stormwater runoff. The new regulations in DC require new construction and significant renovations to be responsible for including and implementing plans to store and reuse stormwater on site.
With about 43 percent of the district covered with impervious surfaces, such as asphalt, pavement, brick, stones, rooftops, and even soil compacted by development , there is little space in DC where rainwater is able to infiltrate the ground, increasing runoff. Stormwater runoff collects trash and other pollutants as it passes over these impervious surfaces. Heavy rains can cause storm sewers to become flooded, especially the ones that share a piping system with sanitary sewers. Flooding from these sewers and stormwater runoff lead to the pollution and damage of our waterways.
Regulated sites in the district will be responsible for retaining a certain volume of stormwater.
- Major land-disturbing activities: retain the volume from a 1.2-inch storm event
- Major substantial improvement activities: retain the volume from a 0.8-inch storm event
A site can meet its responsibility for their stormwater retention volume (SWRv) through complete on-site retention or a combination of on-site and off-site retention. Each site is responsible for retaining at least 50 percent of the SWRv calculated for the site. An additional option to meet requirements is the Stormwater Retention Credit (SRC) trading program, which allows you to purchase SRCs from other sites who are retaining more than their required amounts.
Stormwater can be retained and used through Best Management Practices (BMPs), including:
- Green Roofs
- Rainwater Harvesting
- Impervious Surface Disconnection
- Permeable Pavement Systems
- Filtering Systems
- Open Channel Systems
- Storage Practices
- Proprietary Practices
- Tree Planting and Preservation
Following one or several of these BMPs can also save you money. By integrating BMPs into your design, you can qualify for discounts on the two stormwater fees that are charged in DC. Additionally, if you implement an initiative such as Rainwater Harvesting, you can use the grey water collected in some of your plumbing in the building, therefore decreasing your water use.
DDOE has created a guidebook that gives detailed information about the 2013 Stormwater Management and Soil Erosion and Sediment Control and BMPs. There is a transition period for full compliance to the Stormwater Rule based on the type of project being executed.