Show students the provided slides as you discuss.
Green Roof – Green roofs are designed to absorb rainwater so New York’s sewer system isn’t overwhelmed during major rain events. Rainwater is absorbed and “held” on roofs rather than running off into our storm sewers. It waters specially-suited plants and then evaporates from the roofs to support the continued working of the water cycle. Green roofs have the added benefit of absorbing heat and cold and modulating temperature fluctuation, which lowers heating and cooling costs for their buildings and reducing wasteful energy use.
Slideshow image shows how green roofs can easily be integrated into existing residential and commercial buildings on a small scale. Larger local projects include a recent greenroof installation in the Javits Center in Manhattan and on public buildings in Brooklyn and the Bronx.
Bioswale – Bioswales intervene when water is already running off into New York’s storm sewers. Curbside cuts direct water into “rain gardens” that can absorb water and keep it from running into drains. Any excess water that does accumulate can exit out at the other side.
For an excellent series of cross-sections on NYC bioswales, see the NYC Department of Environmental Protection’s handout “Bioswale Care Handbook”: http://www.nyc.gov/html/dep/pdf/green_infrastructure/bioswalecare_handbook.pdf
Slideshow image shows new bioswale on Dean Street, Brooklyn. Notice the two curb cuts, the different types of plants, and the gravel used right at edge to facilitate quick drainage.
Permeable Concrete – Permeable concrete can be used in certain situations to provide the hard surfaces we might like for walking and playing, with the added benefit of allowing water to seep through to the ground below so it doesn’t run off into our stormwater system. Right now permeable concrete isn’t strong enough to support high-traffic wear and tear like on our roads, but it can be integrated into parkland for walkways and play surfaces. Engineers and scientists are always looking to improve permeable technology so we can integrate it more in the cityscape!
If you chose to make permeable concrete, you can demonstrate its properties by running water through the sample and asking students what they see.
The slideshow image shows installation of Stormcrete – a brand of permeable concrete – in Springfield Gardens, Queens. Springfield Gardens is vulnerable to rising sea levels and flooding during major storms.
Wetlands Restoration – water health isn’t just about runoff. Once polluted water is in our waterways there are ways to clean it naturally. The same processes of filtration and absorption are at play when we plant wetland grasses and re-establish organisms like oysters, which naturally clean and filter water.
The slideshow image is taken from Brooklyn Bridge Park, where landscape architects and city park planners have worked to integrate wetlands into the new park (along with permeable pavers, foreground).