A SCENARIO PLANNING APPROACH FOR SCHOOL GREEN ROOFS TO ACHIEVE STORMWATER MANAGEMENT BENEFITS: A CASE STUDY OF BRIER'S MILL RUN SUBWATERSHED

Abstract

In 2010, the United States Environmental Protection Agency (EPA) determined the Total Maximum Daily Load (TMDL), a "pollution diet", for the Chesapeake Bay watershed for six states (New York, Pennsylvania, Delaware, Maryland, West Virginia, Virginia) and the District of Columbia. The EPA required responsible agencies to develop statewide Phase I Watershed Implementation Plans (WIPs) to support the implementation for TMDLs. Previous planning efforts included the development of Subwatershed Action Plans (SWAPs), which provided a baseline of conditions, proposed tools for achieving TMDL reductions and visions for the subwatersheds. In 2012, the Phase II WIP process was developed to refine Phase I plans at the county level, including more local details about a variety of green infrastructure interventions to optimize nutrient and sediment load reductions. While green roofs were considered an important tool in the SWAP plans, they were not included in Prince George's County's Phase II WIP plans. Recently, Prince George's County has implemented a new green roof incentive policy. In light of this new policy, this research explores how green roofs might contribute to reducing TMDLs. The research uses Brier's Mill Run Subwatershed as a case study to demonstrate the benefits of both the incentives and the green roof as a tool in the SWAP plan. The objective of this research is first to document the specific role of green roofs in stormwater management in Brier's Mill Run Subwatershed. Secondly, the thesis provides three metrics to measure and compare the stormwater management benefits of each proposed institutional green roof in the research site. The third goal is to use a scenario approach to achieve school green roofs benefits that contribute to the stormwater management goals of the subwatershed.