Harvesting Stormwater for Urban Farm Irrigation

Abstract

Rainwater control and reuse contributes to a healthier environment, especially in urban regions. A rainwater harvesting system was designed for an urban farm located in the Germantown section of Philadelphia, Pennsylvania. This design includes a transport mechanism to convey captured rainwater from the roof, approximately 2350 ft2, to a constructed wetland system, where it will be treated. The water, treated to EPA non-potable reuse standards, will then be stored or transported by pumping to the adjacent half-acre farm to irrigate the crops. When the system fills, overflow is controlled and directed to the combined sewer system. Research has shown elevated heavy metals concentrations in runoff coming from aging roof structures; these concentrations can be reduced substantially through treatment in a constructed wetland. Onsite treatment of rainwater reduces the farmers’ dependency on municipal water resources and usage costs. Additional benefits of this system are reducing the hydraulic load and improving water quality of runoff from the property into Philadelphia’s combined sewer system.