In 2022, Washington DC installed 2 bioretention systems across 2.6 acres to manage runoff. 1 year later, they could retain 2,627 cubic feet of stormwater per storm

A residential street in Washington, D.C., now has a surprisingly large job during heavy rain. Two planted stormwater systems can retain about 2,627 cubic feet of water per storm. That works out to nearly 20,000 gallons that can be held before runoff moves farther downstream. The project sits on Hamlin Street NE, inside the Hickey Run watershed, where urban runoff has long created water-quality concerns.

The number is striking because the project does not occupy some enormous flood-control basin. It uses two bioretention facilities built into a residential streetscape. Beneath the planted areas are stormwater chambers that provide extra storage when rainfall arrives quickly. The design combines living landscape features with underground infrastructure to slow and hold water.

That matters in a city where pavement changes what rain normally does. Water falling on soil can soak into the ground gradually, but streets and other hard surfaces send it elsewhere quickly. On Hamlin Street, runoff from about 2.75 acres reaches the two systems, with roughly half that area covered by impervious surfaces. Capturing some of that water earlier can reduce the volume and speed reaching Hickey Run.

What was built on Hamlin Street?

The project is located near Mills Avenue on the southeastern side of the 2000 block of Hamlin Street NE. The District Department of Energy and Environment selected the area because it had strong potential for stormwater treatment. The site receives drainage from about 3.1 acres, including approximately 1.3 acres of impervious cover.

The street also had an unusual history within the neighborhood. Hamlin Street was developed before the District established its current stormwater regulations, so the roadway itself lacked stormwater controls. Meanwhile, eight nearby homes had already adopted stormwater practices through the RiverSmart Homes program. That neighborhood participation helped make Hamlin Street a logical location for a larger public retrofit.

The final project contains two different bioretention facilities. One follows the curb in a long, curved layout, while another uses a larger terraced design nearby. Engineers added underground storm chambers because the drainage area was substantial. Together, the systems provide about 2,627 cubic feet of retention, according to the Chesapeake Stormwater Network.

How do bioretention systems handle rain?

A bioretention system gives stormwater somewhere to go before it races into a drain. Vegetation and engineered soil slow the water while helping filter material carried from streets and other surfaces. Some water can infiltrate gradually, while additional water can remain temporarily stored within the system.

Hamlin Street takes that basic idea a step further. Underground chambers sit beneath the bioretention filter media, creating what officials describe as a green-gray hybrid approach. The planted surface handles treatment, while the chambers provide additional storage below it. That combination allows the project to capture more runoff without requiring a large open detention basin.

The distinction is important because stormwater carries more than water. Runoff moving across developed surfaces can pick up pollutants before entering drainage systems and streams. By slowing that water and treating it closer to its source, bioretention can reduce both runoff volume and the pollutants moving downstream.

Why does Hickey Run matter?

Hickey Run is a relatively small waterway, but its location makes it important to Washington's wider water system. The Hamlin Street site sits inside the Hickey Run watershed, which is itself part of the larger Anacostia River watershed. Water leaving this neighborhood therefore becomes part of a much larger downstream system.

The District says the project is intended to reduce runoff and pollution before water reaches Hickey Run. It also aims to prevent erosion and improve natural habitat within the watershed. Those effects can extend toward the Anacostia and Potomac rivers, making a neighborhood project relevant beyond its immediate street.

This is where the 20,000-gallon figure becomes more meaningful. The amount is not large compared with a major reservoir or municipal flood-control project. But the system is working with runoff from only a few urban acres. Repeating that approach across many streets could create a much larger network for managing rainfall.

Why did the project take years to reach the street?

The idea was not created overnight. Hamlin Street had been identified as a potential stormwater retrofit before construction began, with planning and design continuing through several stages. District records show that construction began in fiscal year 2022 and the project was completed in fiscal year 2023.

That timeline reflects one challenge with urban green infrastructure. Engineers cannot simply place a rain garden wherever there is unused space and walk away. Drainage patterns, underground utilities, streets, sidewalks, maintenance and agency requirements all have to work together. The Hamlin Street project required collaboration among several District agencies before its final design could be built.

The result also had to fit an existing neighborhood rather than a newly planned development. The final design incorporated stormwater storage, larger tree wells and an alignment that could accommodate a future sidewalk. It was therefore designed around several needs at once, rather than treating stormwater as the only consideration.

Could small projects like this make a larger difference?

One Hamlin Street retrofit cannot eliminate Washington's stormwater problems. Its value lies in demonstrating what can happen when small drainage areas receive targeted infrastructure. The District is already using bioretention and other green infrastructure approaches in different parts of the city.

There is also a practical lesson in the project's location. Stormwater management does not always require a giant new structure or a dramatic change to a city landscape. A curbside system, planted basin and underground chamber can quietly perform the work during a storm. For residents, much of that infrastructure may look like landscaping until the next heavy rainfall arrives.

The Hamlin Street project later received recognition from the Chesapeake Stormwater Network as a 2025 award winner. That attention reflects the project's targeted design and its ability to combine stormwater storage with neighborhood improvements. The more difficult question now is whether similar systems can be scaled across other urban watersheds.

For American cities facing heavier rainfall and increasingly paved landscapes, that question has practical weight. Every storm begins locally, often on an ordinary street where rain has nowhere natural to go. Hamlin Street shows one way that water can be intercepted before it becomes someone else's downstream problem. The next challenge is determining where many more streets could do the same work.