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Detention Basin Retrofitting

detention basin

detention basin



Overview
In an effort to keep local streams and rivers clean, The City of Elgin is working on retrofitting its stormwater detention facilities to improve the community’s water quality. Historically, detention facilities were designed solely for flood control. These facilities had concrete channels that moved stormwater quickly through the basin and kept the bottom of the basin dry so it could be mowed. With the city’s transformation into a community focusing on sustainable practices and the creation of the Sustainability Action Plan (SAP), it has adopted an approach to improve stormwater quality and decrease stormwater facility maintenance.

Jayne Industrial Basin
In early 2011, the detention basin at the corner of McLean Blvd. and Holmes Rd was the first of the city’s basins to be retrofitted. The project consisted of removing the concrete lined channel and installing native and wetland plantings after re-grading the basin. Detention basin retrofitting is an example of a Stormwater Best Management Practice (BMP). A Stormwater BMP is a practice used to manage the impacts of stormwater runoff. Other examples of stormwater BMPs are wetlands, rain gardens, swales, and permeable pavement.

The removal of the concrete channel slows the flow of water and diverts the water onto the stormwater basin floor. This allows some of the pollutants in the water to settle out and be absorbed by the plants and microorganisms in the soil of the basin floor.

By replacing the basin’s turf grass with native plantings, the required maintenance of the basin has decreased. Turf grass is unsustainable because it requires regular mowing, watering, fertilizing, and weed control. Native plantings are a more sustainable alternative because they are drought resistant, promote infiltration and biodiversity, and require little maintenance. With dense root systems making up two thirds of their biomass, native plantings enrich the soil with their organic matter. They also have high water-holding capacities and draw water deep into the earth, replenishing the shallow aquifer, because of the great depths their roots reach. Native plants support biodiversity by providing food and habitats for native birds and insects. The growing point of prairie plants is just below the surface, making them resistant to fire; an annual controlled burn is used to maintain the plants and fertilizes the plants with its ash.  

detention basin

Before

detention basin

detention basin

After

detention basin