We are developing guidance to improve the hydrologic performance of rain gardens and bioretention basins. This guidance will be based on field evaluation of local rain gardens and research on how plants, shrubs and trees improve soil infiltration capacity. Twenty rain gardens in Washtenaw County have been assessed. These gardens have soils that range from clay loam and sand clay to hard clay. In our first set of paired, digitally-filmed rain events, we found that the native plant rain garden was draining more than 1-inch/hour and the turf grass rain garden (same sandy clay soil) was drawing down at roughly half that rate. In fact, over a two-month monitoring period and seven separate events, the native plant rain garden only accumulated water in one of seven and the grass garden in two of the seven events. Monitoring and guidance development will be on-going for at least another year.
Scott Dierks, GEI Consultants, Inc
Scott began his career learning water quality sampling and hydrologic and hydraulic modeling of combined sewer systems in Providence at the University of Rhode Island. He did his masters in ecological engineering waste deep in Florida's swamps at the University of Florida. For the last twenty years he has worked as a licensed professional civil engineer in Michigan with a passion and focus on hydrology, landscape restoration and ecological engineering. His project work spans stream restoration, green infrastructure planning and design and alternative on-site wastewater treatment system design. He is a Senior Water Resources Engineer with GEI Consultants, Inc. in Ann Arbor, Michigan, since 2015.