By Sarah Hippensteel Hall, Ph.D., Manager for Watershed Partnerships
Last month we discussed how green development can reduce flooding, save money, reduce energy use, and improve public health. This month we want to key in on a few of the more popular green development practices and their incentives.
Rain gardens filter out pollutants
Studies show that up to 70 percent of the pollution in our streams and rivers is carried there by stormwater. Rain gardens help filter out stormwater pollution before it flows into streams and rivers.
- Feature attractive landscaping with perennial native plants.
- Are designed to absorb stormwater runoff from impervious surfaces such as roofs and parking lots.
- Allow water to slowly filter into the ground rather than run off to storm drains.
- Allow about 30 percent more water to soak into the ground compared to a patch of lawn.
- Come in a variety of sizes from small or large home-owner style gardens to complex bioretention gardens, and anything in between.
- Can be bowl-shaped or saucer-shaped gardens.
Rain gardens are particularly effective at reducing solids and nutrients – like nitrogen and phosphorus – in stormwater runoff from residential yards and parking lots. Research done by the Center for Watershed Protection found that bioretention facilities installed in parking lots reduced total phosphorous in runoff by 65 percent, total nitrogen by 49 percent, and metals by 95-97 percent.
MCD helped install rain gardens in several locations to demonstrate their effectiveness:
- City of Springfield
- City of Brookville Wenger Woods neighborhood
- Heritage Park in Hamilton County
- Preble County Historical Society
Pervious pavers absorb rain and snow
Pervious pavers are an alternative to a traditional asphalt or concrete driveway.
When stormwater flows over lawns and concrete driveways, it can carry with it chemicals, fertilizers, sediment and oils, which can degrade the quality of water running into storm sewers. Pervious pavers help slow polluted stormwater runoff, allowing the water to soak into the aquifer instead of flowing off the land and into rivers and streams.
Paver driveways and walkways allow rain and snowmelt to soak through the cracks between each paver so that water doesn’t pond during a rainstorm, and ice doesn’t form in the winter.
While concrete or asphalt surfaces may require a lower initial investment, paver systems are known to last decades longer. They also require little maintenance because they aren’t prone to cracking. When pavers need repaired, only the damaged section needs to be replaced, not the entire surface.
MCD uses pervious pavers to increase infiltration and slow runoff at its headquarters building in downtown Dayton. MCD also helped install pervious pavers at several homes in the City of Brookville’s Wenger Woods neighborhood.
Green roofs mitigate heat and improve air quality
Green roofs, which are made from natural plant material, have natural thermal insulation properties that keep structures cooler in the summer and warmer in the winter. Green roofs are a layer of light weight vegetation that is installed over a roof membrane. They offer features and benefits not present in a conventional membrane roof such as:
- The vegetation and soil layers protect the waterproof membrane from solar exposure, prolonging roof membrane life.
- The soil provides additional insulation and shades the roof from solar heat gain.
- Environmental benefits – including stormwater filtration, heat island mitigation, improved air quality and increased wildlife habitat.
Green roofs have been used in Europe for centuries, but are still catching on in popularity here. They are particularly cost-effective:
- In dense urban areas where land values are high.
- On large industrial or office buildings where stormwater management costs are likely to be high.
MCD helped install green roofs on several modular homes in the Canal Block Litehouse Development in downtown Dayton. Green roofs are also in use on top of Dayton’s city hall building and Springfield Regional Medical Center.
How you can help
Your community can encourage the installation of green practices – like the three listed above – by updating your development policies to encourage builders to think green.
An easy way to get started is to host a Site Planning Roundtable that brings together local leaders from government, development, and natural resources. MCD staff can, in partnership with local sponsors, assist communities during all phases of the Site Planning Roundtable. Call me at 937-223-1278 ext. 3244 and let’s get started!