Vegetated Roof for Rain Water Harvesting System (RWHS)

About the Program

Category: County Resiliency (Best in Category)

Year: 2014

The EMTOC project is designed LEED Gold and has approximately 4 acres of vegetated roof. The vegetated roof assembly has decreased the heating and cooling provided to the occupant areas and collects rain for RWHS. The County notes using purified potable water for purposes like flushing toilets is a waste of a valuable resource. The treated rainwater harvesting system and proper use of it allows reduction in storm water runoff and associated pollution, and supports Environmental Site Design (ESD) mandates for a comprehensive approach to planned developments. This minimizes the impact on streams, rivers and the Chesapeake Bay. The RWHS is designed to meet the MDE Class IV water quality requirements for Suspended Solids or nephelometric turbidity units (NTU). The criterion set by MDE is 2NTU daily average, not to exceed 5 NTU. The turbidity check, which determines muddiness created by stirring up sediment / suspended foreign particles, is addressed first by the green roof, which filters out a significant amount of particulate. The cascade filters remove large debris and organic materials to approximately 280 microns. The final removal of suspended particles is a function of the filter porosity, which is 5 microns.