The University of Delaware Rain Garden: Environmental Mitigation of a Building Footprint

Abstract

Green technology best management practices such as rain gardens are often used to retrofit and mitigate the footprints of buildings and impervious cover in watersheds. Rain gardens are a recent technology created to help remedy water abuses. A rain garden promotes the environmental benefits of storm water mitigation, water conservation, groundwater recharge, and reduced waterbody pollution. This research documents the process of implementing a rain garden from initiation through completion on the campus of the University of Delaware in the White Clay Creek National Wild and Scenic River watershed. The design considered the surrounding drainage area, infiltration rates, and plant selection. Through this project the researcher sought to create a demonstration that could inspire the public to create rain gardens. Initial goals of the research included preventing standing water from remaining in the garden after a four-day period, avoiding amendments to the native soil, and foregoing the removal of excavated soil from the rain garden depression off the site. In addition, no plant species were to be planted within the rain garden depression that were not native to within a five-hundred mile radius of Newark, Delaware. From this research, recommendations were generated for those wishing to install a rain garden. These include establishing initial goals, involving stakeholders, considering alternative overflow outlets, and inspecting soils to at least a 6-foot (1.83 m) depth. Further recommendations include stabilizing the contributing drainage area; utilizing aged, triple shredded hardwood mulch; and considering berms for use in capturing runoff and regulating outflows. In addition to mitigating the impacts of stormwater runoff from the buildings and parking lots in the watershed, the rain garden also serves as an outdoor education and research laboratory on campus.