Design standards have been developed for vegetated systems, permeable pavement, and tree space design and the draft release contains design guidelines, drawings, and specifications.
WASHINGTON, DC – The District Department of Transportation (DDOT) has released Draft Design Standards for Low Impact Development (LID) and Green Infrastructure (GI) for the public right-of-way (ROW) in the District. Design standards have been developed for vegetated systems, permeable pavement, and tree space design and the draft release contains design guidelines, drawings, and specifications.
LID and GI practices are methods to restore ecological systems of urban cities. Hardscape surfaces in cities such as roads and sidewalks lead to significant stormwater runoff and difficult growing conditions for urban trees. LID designs for streets reduce and filter stormwater runoff at the source before it flows into the storm drain system. Vegetated stormwater reduction practices such as bioretention areas capture and filter stormwater while creating a streetside amenity. Permeable paving allows water to flow into pavement and through a storage area. Both types of practices will infiltrate water where the soil conditions are suitable. Improved tree spaces create larger soil volumes which capture more stormwater and allow capacity for larger, healthier urban trees.
District agencies and private development have been designing and constructing LID and GI facilities in the ROW for about a decade. Starting in summer 2013, all public and private construction projects will be required to meet new Stormwater Regulations issued by the District Department of Environment. DDOT’s LID and GI standards will be the recommended practices to meet these requirements in the ROW.
To develop the standards, a multidisciplinary and multi-agency team and council of experts reviewed existing projects, practices from other cities, and university research to incorporate the best practices into DDOT’s LID and GI Standards. DDOT will also be developing an illustrative manual, maintenance schedules, and performance measurement tools for LID and GI.
The draft standards may be downloaded from DDOT’s LID website:
DDOT welcomes any comments on the draft standards by Thursday, April 18, 2013.
Please email comments to Meredith.Upchurch@dc.gov or mail comments to District Department of Transportation – IPMA, Attention: Meredith Upchurch, 55 M Street, SE Suite 400, Washington, DC 20009.