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Abstract: Session E  4:10 pm (Back to Session E)
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Incorporating Stream Restoration Techniques in Stormwater Management

Meghan Gloyd, PE
Biohabitats
Baltimore, MD

Authors: Meghan Gloyd, PE; Phil Jones, PE; Darian Copiz

This project utilized stream restoration techniques to retrofit an existing stormwater management pond in Gaithersburg, Maryland as a part of the Montgomery County’s Department of Environmental Protection’s (MCDEP) efforts to comply with its Municipal Separate Storm Sewer System (MS4) permit requirements.  The existing dry pond, located in the Great Seneca Creek watershed on Maryland-National Capital Park and Planning Commission (M-NCPPC) property, was retrofitted to provide innovative water quality management for the 48.5-acre drainage area. The existing pond outlet works were removed and replaced with a cascade structure, which regulates flow to the sand filter constructed within the pond footprint.   A new sand filter basin was constructed in open space immediately downstream of the existing basin and features a sand berm with a gabion stone core.  A riffle controls the flow into the new basin.  Both basins are designed to pond a foot and a half of water until infiltration occurs, improving water quality through filtration and promoting infiltration. The downstream reach was restored using a riffle pool sequence.  Due to the innovative nature of the design, the permitting process involved navigating a host of challenges.  Construction was completed in the fall of 2018.  The presentation will include observations from the design phase, construction phase, and project performance during the first year of installation.