A North Carolina Field Study to Evaluate Greenroof Runoff Quantity, Runoff Quality, and Plant Growth

Recent federal and state regulations require stormwater runoff to be treated by structural controls in ultra-urban development. Several practices have been used in North Carolina; however, a less common stormwater management practice is the greenroof. Two extensive greenroofs have been constructed within the Neuse River Basin. The first was constructed in April 2002 at the Neuseway Nature Center in Kinston, NC. This 19 m² (200 ft²), 3% pitched roof is composed of 10 cm (4 in) deep soil substrate, planted with a variety of species of delosperma and sedum. A second greenroof was constructed atop a storage building of Wayne Community College in Goldsboro, NC. This essentially flat, 70 m² (750 ft²) greenroof is constructed with soil substrate depths of 5 cm (2 in) and 10 cm (4 in) and is planted with the same variety of vegetation as the greenroof in Kinston, NC. Both greenroofs are compared to a control roof of typical design for research purposes. As of January 2003, sampling equipment has only been installed at the Wayne Community College; installation will complete in Kinston, NC, in early 2003. Stormwater runoff quantity and quality data is still pending and will be available for both greenroofs in early spring 2003. Five plant species are tentatively recommended for growth in eastern and central North Carolina: delosperma nubigenum, sedum reflexum, sedum album, sedum album murale, and sedum sexangulare.