Water Resources Research Act Program

Details for Project ID 2006AL50B

Evaluating Bioretention Nutrient Removal in a Rain Garden With and Internal Water Storage (IWS) Layer

Institute: Alabama
Year Established: 2006 Start Date: 2006-03-01 End Date: 2007-02-28
Total Federal Funds: $17,444 Total Non-Federal Funds: $35,254

Principal Investigators: Mark Dougherty, Charlene LeBleu

Project Summary: A rain garden is a man-made depression in the ground that is used as a landscape tool to improve water quality. The rain garden forms a biretention area by collecting runoff, storing it, and permitting it to be filtered and slowly absorbed by the soil. The bioretention comcept is based on the hydrologic function of forest habitat. A nutrient removal or filtering process takes place as the water comes in contact with the soil and the roots of the trees, shrubs and vegetation. The first flush of rain water is ponded in the depression of the rain garden, and contains the highest concentration of materials washed off impervious surfaces. Typically, organic matter is blended into a sandy soil with about 30% of native top soil. The planting mixture provides a source of water and nutrients for the plants to sustain growth while clay particles adsorb heavy metals, hydrocarbons and other pollutants. The use of these innovative techniques have been successfully used in the northeast portion of the United States. In the southeast, North Carolina has led the way for implementation of stormwater infiltration management practices. Various groups in Alabama have indicated an intertest in installing some of these practices, but hesitate partly due to lack of research evaluating and demonstrating these practices locally. The use of bioretention devices is poised to expand because their use appears to improve water quality, and they can be designed to be aesthetically pleasing. This project will construct, monitor, and compare two different bioretention areas.