The Oregon Avenue Watershed Green Streets (OAWGS) project was part of the District Department of Transportation’s (DDOT’s) efforts to address requirements for stormwater retention in accordance with its MS4 permit issued by the Environmental Protection Agency (EPA). DDOT and its consultant team developed the OAWGS project to reduce runoff from streets within the 360-acre Oregon Avenue Watershed area and reduce impacts to nearby Rock Creek Park.  The park’s outfalls and tributaries have been severely impacted by stormwater runoff from the roadway.

The consultant team developed a prioritization system for green infrastructure (GI) facilities such as bioretention, permeable pavement, and other appropriate techniques to retain and reduce stormwater runoff. The consultant team designed site specific GI practices considering design effectiveness, aesthetic, environmental and transportation conditions, and community concerns.

The GI facilities capture a combined 28,000 SF of impervious surface within the right-of-way. However, the total drainage area captured by these facilities is more than 220,000 SF. Despite the constrained conditions found in urban environments, the retention volumes achieved for all GI facilities in the project was more than 11,000 CF, with an average retention of 290 CF for bioretention planters and 2,800 CF for the green alley.