What is a rain garden?
A rain garden is a shallow depression in the ground that captures runoff from impervious surfaces such as driveways, roofs, parking lots, and patios, and allows it to soak into the ground. Rain gardens are typically planted with native plants and work together with the soil to provide important environmental benefits. The garden absorbs and filters pollutants and returns cleaner water through the ground to nearby streams. Rain gardens reduce flooding by sending the water back underground, rather than onto the street. They also provide habitat for beneficial insects and wildlife.
Transylvania’s rain garden borders the back of Haupt Humanities building and Haupt Plaza. The 50 by 20 foot planted basin performs both utilitarian and aesthetic functions. Previously, there were storm water issues at the plaza side of the building. Storm water ran across the impervious surface of the plaza toward the building wall and down into the basement and foundation. As part of the plaza’s renovation in 2006, the area was re-graded and an infiltration basin, designed as a rain garden, was installed.
The rain garden is composed of a shallow basin with several layers of material, including:
The basin functions to slow down the flow of rain water by providing a deep medium through which it must soak before reaching a piped outlet. The amount of runoff is reduced by uptake from the plants, evaporation, and infiltration into the soils beneath.
The plantings are native perennials, including Little Bluestem; Lobelia; Sea Oats; Butterfly Weed; Copper, Yellow, and Blue Flag Iris; and Sensitive Fern. Over time they will fill in the entire basin. Their function is to soak up water and filter any pollutants that enter the basin with the rain water. The rim of the basin is planted with dwarf Sweetspire and bordered at the building side with Oakleaf Hydrangea. Small ornamental trees and additional shrubs are planted beyond the basin. Together, the plants provide a scene of color and texture that adds to the liveliness of the plaza.
The Haupt Plaza rain garden was designed by Denise Y. O’Meara, RLA, ASLA, senior landscape architect at Ross Tarrant Architects, Inc., and is maintained by Transy’s grounds staff.