CINCINNATI, Ohio -- The city of Cincinnati is eyeing overhauling its antiquated storm water management system and Ohio State University Extension may have a "green" solution to reducing the 14 billion gallons of raw sewage that is discharged annually.
Under a three-year contract with the Metropolitan Sewer District of Greater Cincinnati, David Dyke, an OSU Extension educator in agriculture and natural resources, is exploring contour infiltration planting (CIP). The technique involves planting vegetation along the contour of a landscape to capture, infiltrate and redirect runoff during big rain events.
Contour planting is not a new concept. It's a common practice in agriculture to reduce soil erosion, and is widely used out West to conserve water in arid regions. But Dyke may have found a new use for contour plantings in urban areas, specifically for storm water management.
"I found little to no literature when researching information on urban contour plantings for storm water management," said Dyke, who was inspired by the idea from past experiences of maintaining blueberries on hillsides. "I thought, 'What's the difference between those hillsides and the hills of Cincinnati?' Nothing. There's no reason why we can't do something like this in the city."
Cincinnati's hilly geography, along with its clay soils, is a big reason why contour infiltration planting has a good chance for success. The technique involves planting vegetation on raised beds (8-12 inches high), following the contour of the landscape at a 2 percent slope. During rain events, the contour plantings are the right height to capture and absorb water, and what is left over gently flows away from the slope to be redirected to other locations, such as a street sewer or a rain garden.
Dyke said that any kind of vegetation can be used in contour planting, even plants like trees and shrubs that require low maintenance.
"Vegetation plays a key role in shaping the landscape because of its ability to absorb tremendous amounts of water," said Dyke. "A mature tree, for example, can absorb over 1,000 gallons of water a year. Just imagine what 100 trees in a contour infiltration planting area could do."
In addition to capturing and conserving water, contour infiltration plantings would also reduce irrigation needs, limit storm water run-off, and reduce the energy and money involved in treating storm water discharged in water management systems.
"The contour infiltration plantings allow water to become an asset, providing moisture for gardens or other uses, while beautifying the landscape, rather than it be a liability to be treated at taxpayers' expense," said Dyke.
OSU Extension in Hamilton County, along with the Metropolitan Sewer District of Greater Cincinnati, has formed a partnership with other entities in the area to establish a contour infiltration planting demonstration project in Delhi Township Park in Hamilton County. The partners include: Project Evergreen, "Horticulture" magazine, Hamilton County Soil and Water Conservation District, Natural Resources Conservation Service, W.A. Natorp Company, Delhi Township Park District, landscape designer Tim Young, Delhi Flower and Garden Center Landscaping and the Hamilton County Master Gardeners. W.A. Natorp Company and Delhi Flower and Garden Center Landscaping donated all the plant materials for the project.
Dyke said the contour infiltration plantings are an alternative to the more traditional method of storm water management construction, which involves transporting runoff through a system of gray pipes or channels.
"It would cost the city $3 billion for five miles of storm water tunnels," said Dyke. "Contour infiltration plantings impact everybody. They are good for the individual, good for the city, good for the industries, and its good for the environment. In this case, green is cheaper than gray."
The contour infiltration planting project is just a small part of a comprehensive storm water management strategy, which includes green initiatives, launched by OSU Extension and the Metropolitan Sewer District of Greater Cincinnati. OSU Extension has also compiled and released storm water management handbooks for industries and nurseries/landscape companies and a rain garden handbook for homeowners.
For more information on the contour infiltration planting project, contact Dave Dyke at (513) 505-1202 or e-mail firstname.lastname@example.org.