Rain Gardens and Other Natural Solutions for Stormwater And Water Quality Management

G. Dodd Galbreath, Tennessee Department of Agriculture

Our April 25th meeting featured a most enjoyable and informative program on innovative stormwater management techniques. Dodd Galbreath came to the attention of CFWA stakeholders at a previous meeting when we viewed DVD presentation, “Stormwater, Erosion, and You”, produced by Water Works. Dodd appeared in a taped segment of Tennessee Wild Side, where he explained the uses and benefits of Rain Gardens as a natural solution in stormwater management.

“Water follows the money” is becoming an ever more meaningful truth in our society. But nature has always known the value of water. In an undeveloped landscape, about 50% of water is taken into the soil, and is released slowly to replenish springs and streams, or is stored in aquifers. In a developed landscape, the situation is much different. Even just 10 - 20% impervious surface, a single dwelling on a lot, typically reduces soil uptake by 8%; with more houses, e.g., a typical subdivision, the soil uptake is reduced from 50% to just 35%. What does this mean? Stormwater rushes off our developements in streams, carrying pollutants from the surfaces it contacts, causing flooding, stream scouring and other erosion, and resulting in a significant loss of water resources.

Low Impact Development (LID) construction design techniques integrate biology, engineering, soil science, plant science, horticulture, landscape architecture, city planning and other sciences and the arts. In the case of stormwater management, techniques include bioretention basins (“rain gardens”), swales and filter strips, tree boxes (in urban street design), and permeable pavement. Through a series of examples showing LID techniques in the design of individual home, housing developments, and urban streets, our speaker showed the great economic and resource value of LID techniques, and the remarkable aesthetic value these measures have over conventional “concrete and pipe” stormwater management. LID features incorporated in neighborhoods across the nation are saving municipalities about 1/3 the cost of constructing conventional stormwater management structures, and reduce stormwater runoff by over 90%. Practicing what it preaches, the Tennessee Department of Agriculture is installing a number of LID features in the Ellington Agricultural Center in Nashville.

A difficulty in applying modern stormwater management techniques is, somewhat ironically, that they may not be in line with city permitting codes, which are often based on the “concrete and pipe” construction methods. Helping city engineers and developers “get on the same page” with respect to beneficial construction practices is just the sort of thing watershed organizations are meant to do, and CFWA will certainly continue to fill the role in promoting LID stormwater management techniques.

For more information on LID, you may contact Dodd Galbreath at 615-837-5492 or dodd.galbreath@state.tn.us. If you would like a copy of Dodd’s excellent PowerPoint presentation, let us know and we’ll send you one (cfwa@blomand.net). Further information can be found in links listed at the IDIWQ website (http://iweb.tntech.edu/jharwood/).