County, Maryland, Department of Public Works and Transportation designed and constructed a
linear rain garden for the median along Adelphi Road in the late 90s. Originally planned as a
raised curb section, the median was redesigned as a landscaped infiltration/bioretention swale.
Designs such as this one make multifunctional use of the roadway for stormwater controls.
The Maryland State Highway Administration (MSHA) is currently involved in a multi-year
research and demonstration project that will develop standards and specifications for LID
strategies applied to state highways. A pilot project planned along
US 1 in Mt. Rainier,
Maryland, will also use monitoring to demonstrate the effectiveness of selected LID techniques
in meeting TMDL compliance requirements. Another portion of the project involves the
rehabilitation of a 6-year old bioretention facility located in a restaurant parking lot in
Colmar Manor, Maryland. Originally constructed by Prince George's County, the bioretention
facility will be retrofit to comply with current bioretention technology standards. The facility
will also include sampling ports for future demonstrations of pollutant removal efficiency.
In Seattle, Washington, as part of the Urban Creeks Legacy Projects,
Seattle Public Utilities enacted a pilot project called SEA Streets (the Street Edge
Alternatives project), which aims to reduce the impact that streetscapes have on local stream
watersheds and salmon habitat.1,2
SEA Streets is a comprehensive approach that manages stormwater, minimizes impervious surfaces,
and eases traffic. It complements an ongoing effort by Seattle Public Utilities and Seattle
Transportation to address street improvements in areas that do not have traditional piped
As shown here, the SEA Streets Project focused on Broadview, a residential section of northwest
Seattle located in the Pipers Creek Watershed. The alternative streetscape is intended to change
the paradigm that the traditional curb and gutter system is necessary. Vegetated swales, bioretention areas, and infiltration trenches are used in conjunction with traditional drainage
infrastructure to collect and treat runoff close to its source. The designers worked with
property owners to integrate SEA Streets bioretention areas into existing grades and achieve a
functional transition between public and private property. As on other streets, property owners
are responsible for maintaining most of the landscaping, even though it serves as a replacement
infiltration/filtration system for the storm drains. Seattle Public Utilities' long term goal is
to retrofit the ditch and culvert drainage system that currently dominates the northern part of
the city using SEA Streets and other natural approaches to manage runoff.
City of Maplewood, Minnesota, has implemented a very successful
program that uses bioretention in street drainage improvement projects for older neighborhoods.3,4 Instead of curb and gutter systems,
neighborhood rain gardens (bioretention cells) are used to decrease the runoff volume, improve
runoff water quality, reduce construction costs, and maintain the character of the neighborhood.
To assist in the acceptance and construction of the neighborhood rain gardens, the City provides
prototype layouts with such appealing themes as easy daylily garden, Minnesota prairie garden,
butterflies and friends garden,
Maplewood is able to recycle street material for the base aggregate of the gardens, obtain
reasonably priced landscape plants from the County Correctional Facility's greenhouse, and engage
neighborhood residents in the cell construction through a block-wide planting day/block party.
Besides saving money and bringing the neighborhood together, the projects are also a hydrologic
success. For example, an engineer with the City cites a mid-1990s pilot project that now generates
no runoff, i.e. it is 100% contained in the neighborhood! For communities looking to implement
similiar projects, Minnesota's Metropolitan Council Environmental Service5
provides alternative stormwater conveyance options grants to help communities use natural
processes to do the work of stormwater management.