Rain Gardens

Capturing Rain to Help Our Environment

Developing and implementing sustainable solutions to public space issues is a priority for the Golden Triangle BID. Like many city downtown areas, Washington’s central business district is mostly comprised of impervious surfaces like roads, sidewalks, and rooftops. When it rains, these hardscapes don’t allow that water to infiltrate into the ground as natural landscapes like forests or meadows would. Instead, thousands of gallons of stormwater flow from these surfaces into our storm drains, carrying pollution like trash and car oil to Rock Creek and the Potomac River. To help clean up our local streams and rivers, the Golden Triangle BID is diverting thousands of gallons of polluted stormwater from sidewalks and streets into rain gardens, where it is filtered by plants and specially engineered soils.

Rain Gardens in the Golden Triangle

Since 2012, the BID has built six rain gardens and has converted 12,000 square feet of asphalt and concrete to green space. This includes the installation of a rain garden at the Rhode Island and M Street island in 2012, four rain gardens at the corners of 19th and L Streets in 2014,and a sustainable rainwater harvesting system in Duke Ellington Park in 2017. These projects have been completed with funding from DC’s Department of Energy & Environment and the Environmental Protection Agency.

The four rain gardens located at the corners of 19th and L Streets are recognized as Certified Wildlife Habitat™ by the National Wildlife Federation. Adding to the beauty of the rain gardens at the corners of 19th and L Streets are four public art sculptures created by artist Foon Sham.

The BID’s dedication to this project helped the Golden Triangle achieve LEED Platinum, the highest level of LEED certification, from the U.S. Green Building Council. It is the first BID in the world to be certified through the LEED for Communities program.

The Greening of 19th Street

Currently, the BID is building 10 new rain gardens and 10 expanded tree boxes along both sides of 19th Street between K and M Streets. When completed this fall, the project will add more than 4,500 square feet of green space, lining two full blocks on one of the most vibrant corridors in the central business district.

The benefits to a project of this scale are numerous:

  • The rain gardens will be able to capture and filter up to 43,000 gallons of polluted runoff per storm. This will reduce the risk of local flooding and help clean up our waterways.
  • 29 trees, planted in fall 2019, will provide cooling shade to the sidewalks, lowering the area’s heat island effect. They will also help filter out harmful air pollution and mitigate traffic noise.
  • 400 new native plants, also planted in fall 2019, will provide an additional corridor of much-needed habitat for pollinators such as bees and butterflies.
  • 4,500 square feet of new green space may help improve the mental and physical well-being of the thousands of pedestrians that pass by each day. People are happier around trees!

How Do Rain Gardens Work?

Rain gardens are built lower than the neighboring road or sidewalk and are carefully graded to form a slight depression. This allows them to capture and hold stormwater runoff, which flows in from the street via curb cuts. The water then soaks into the ground instead of pouring into storm drains and eventually the Potomac River or Rock Creek. Plants in the rain garden are specially selected for their ability to both absorb lots of water and survive long dry periods between storms. Soil, mulch, and stones also channel and filter water during storms before releasing it slowly into the ground.

Plant Selection for the 19th Street Rain Gardens

In November, the BID will plant 33 trees and more than 400 native plants in the new rain gardens on 19th Street. The plants will bloom next summer and were specially selected for their ability to absorb lots of water and to survive long dry periods between storms. Several of the plants were chosen for their habitat value for pollinators like bees and butterflies.

These are the plants that have been selected for the new rain gardens and expanded tree boxes:

  • Pin Oak
  • Red Maple
  • New England Aster
  • Swamp Milkweed
  • Blue Mistflower
  • Joe Pye Weed
  • Cardinal Flower
  • Golden Creeping Jenny
  • Shenandoah Switch Grass
  • Sedum Angelina

A Unique Public-Private Partnership

All rain garden projects in the central business district are made possible through a partnership between the Golden Triangle BID and the DC Department of Energy & Environment with funding from EPA. Support for the 19th Rain Gardens project is also provided by Pepco – An Exelon Company, Rockrose, The Tower Companies, Carr Properties, OTO Development, Wawa and Population Services International.

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