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How Green initiatives can help your stormwater collection infrastructure

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From the sky, to rooftops, down the sides of skyscrapers and houses, along roadways, into sewer systems and back into rivers, lakes and oceans. Rainwater really goes a long way before finishing its cycle—and picks up a lot of pollutants along the way.



Here’s how green infrastructure can help keep stormwater treatment costs low in your system.



What is Green Infrastructure?

Traditional gray infrastructure is the network of pipes for sanitary and stormwater management that keep our cities from flooding. Green infrastructure, on the other hand, uses natural processes to reduce the amount of stormwater runoff from entering into gray infrastructure. It helps reduce the conveyance and treatment costs by keeping some extraneous water from entering into your sewer systems.



Green infrastructure attempts to restore some of the natural water cycle into cities that have been built with largely impermeable materials. It keeps the amount of inflow and infiltration to a minimum and works together with more traditional infrastructure to keep unnecessary treatment costs low, and prevent pollution from entering into our water systems.



Why is it a good idea for municipalities?

Many cities are currently ill-equipped to handle the impact of a 100 or even 500 year storm. Chicago’s 500 year storm in 2008 lead to 11 billion gallons of combined sewer water flooding into Lake Michigan—an event that will most likely be more frequent across the country, according to the Intergovernmental Panel on Climate Change (IPCC).



Though it is imperative that we continue to upgrade and maintain our current gray infrastructure systems to handle these storms, funding these projects becomes more realistic with the implementation of green infrastructure to mitigate some of the extraneous water. Gray infrastructure, in the meantime, should remain watertight in order to keep remaining inflow and infiltration out of water systems.



Green infrastructure is a very easy stormwater management strategy to implement. It uses Low Impact Development (LID) and can help out with Best Management Practices (BMP) in your regular gray infrastructure by helping to keep water flow below maximum capacity and prevent Combined Sewer Overflow events (CSOs).



Low Impact Development uses assets from a city or park’s natural resources to reduce imperviousness that concrete or other high impact developments bring to a landscape. These resources are lower maintenance, lower cost, and also ease costs in sanitary and collection systems by reducing the amount of water being treated.



What are some examples of green infrastructure to help mitigate stormwater?

There is a wide range of green infrastructure that cities have begun to implement, or give incentives to developers for implementing. These include, but are not exclusively:



Swales: Also called bioswales, these are essentially grassy ditches in the roadside that filter pollutants and catch stormwater runoff before it enters into a stormwater system.



Rain Gardens: A shallow depression in a lawn with loose soil and vegetation (unlike grass or concrete) to absorb and filter and runoff that would otherwise be heading towards the gutter.



— Permeable Pavement: Is made from materials that simply allow water to flow through, instead of collect on top of a surface. Chicago implemented a Green Alley program with permeable pavement that infiltrates water, instead of creating flooding.



— Constructed Wetlands: Systems that use wetland vegetation and soils to treat water.



— Tree programs: Programs that offer free trees or incentives for planting trees. Tree canopies can also mitigate run off and encourage restoration to the natural water cycle.



Green Roofs: This is infrastructure that can be easily installed onto new building developments in cities. These roofs involve a combination of waterproofing, drainage, filter cloths, and vegetation that absorb water until it evaporates back into the atmosphere, instead of running off buildings and entering into stormwater collection systems.



What cities have already started their own green infrastructure initiatives?

Here are some existing projects to check out:



— Chicago, IL: Sustainable Chicago 2015



— Houson, TX: Bayou Greenways 2020



— Los Angeles, CA: Green Streets Program



— New York, NY: PlaNYC



— Philadelphia, PA: Green City, Clean Waters



— Washington, DC: Sustainable DC