Vegetated Stormwater Technologies
Constructed Wetlands and Infiltration/Water Quality Swales
Stormwater runoff volume reduction can be achieved by a variety of methods that integrate stormwater storage, treatment and infiltration with vegetative elements. These techniques incorporate stormwater infiltration principles into standard site elements such as landscaped beds, traffic islands, constructed wetlands, swales and open grassed areas.

The use of vegetated systems provides for additional environmental benefits by reducing runoff volume through evaporation and plant transpiration as well as infiltration. These systems integrate attractively into the site landscaping and work well in commercial, institutional and residential areas.

At the Flying J truck-refueling terminal near Carlisle, Pennsylvania, Cahill Associates engineered a stormwater recharge design over a sensitive carbonate formation. Special water quality measures were designed, including a two-stage pretreatment system that incorporated a settling unit followed by a sand-peat wetland filtration system, which together removed first flush pollutants from stormwater runoff.

For the Ford Motor Co. manufacturing plant in Detroit, Michigan, Cahill engineers designed an innovative system consisting of porous pavement parking with a subsurface storage bed that distributes stormwater into a vegetated water quality swale. The microbiological processes that occur in the soil root zone treat the stormwater prior to discharge.
Examples

Filtration bed at the Flying J Truck Stop near Carlisle, PA.

Vegetated water quality swale conceptual cross-section detail.

Porous asphalt Mustang Lot adjacent to the vegetated water quality swale.