Graham Avenue Submerged Gravel Wetland

Location:  Berlin, Maryland

Client:  Town of Berlin

The Town of Berlin converted vacant land that once housed an electrical substation into a submerged gravel wetland as part of its ongoing effort to reduce flooding from stormwater runoff and improve water quality in the receiving Maryland coastal bays. EA provided planning, design, grant funding support, and construction oversight for the award-winning project.

Historically, the Town had experienced flooding during small storm events with a minimal amount of rainfall. With the increased threat of extreme weather caused by climate change, the community was concerned about safety, potential effects on critical facilities, erosion to waterway banks, and disruptions to emergency responders from flooding within the streets and residences.

As part of ongoing efforts to address concerns, a stormwater best management practice was planned for a small property along Graham Avenue. This submerged gravel wetland is an example of green infrastructure, an approach to water management that protects, restores, or mimics the natural water cycle. It serves the dual purpose of storing stormwater runoff and provides a small-scale filter using wetland plants in a rock media to provide water quality treatment.

At the Graham Avenue facility, runoff that drains into the wetland is dispersed throughout the system and released as treated water. Pollutant removal is attained through biological uptake from algae and bacteria within the wetland media. Wetland plants also provide nutrient uptake.

The project treats approximately 155,000 square feet or 3.55 acres of impervious area with approximately 15,000 cubic feet of stormwater storage. The site receives runoff from heavily trafficked roadways and multiple nearby small commercial businesses and has significantly reduced the severity of flooding in the neighborhood. In addition, treatment through the submerged gravel wetland results in nutrient load reductions of 165 pounds of nitrogen, 16 pounds of phosphorus, and 8,400 pounds of suspended sediment annually.

The project was completed in partnership with the Town of Berlin; Goody Hill Groundwork, Inc.; and the Maryland Coastal Bays Program. It was supported through generous grant funding from the Chesapeake Bay Trust and Maryland Department of Natural Resources through the Chesapeake and Atlantic Coastal Bays Trust Fund.

The Maryland Coastal Bays Program honored the Town of Berlin with a Gold Star Award and recognized EA for their Partnership with the Town on the Graham Avenue submerged wetland project.