Through its on-call contract with Montgomery County, MD, RES provided construction services to create a series of 10 roadside basins/cells designed to collect and filter roadside run-off before being discharged into Sligo Creek. Several of the basins/cells were constructed on Maryland National Capital Parks and Planning Commission (MNCPPC) park property, while others were constructed along the road and in the right of way between the sidewalk and curb or within the roadway (curb bump-outs). The project was designed so that run-off to each of these basins is conveyed through a series of modified storm drain inlets draining directly into each respective basin. Once the stormwater is collected in each basin, it filters through several layers of filter media (mulch, bioretention soil, and stone) and is collected in an underdrain system connecting each basin to the existing stormwater infrastructure. Each basin was planted with a variety of native grasses and shrubs. This project combined Infiltration and Filtering Practices, as classified by MDE’s Stormwater Design Manual.