Why Stormwater Treatment Methods Need to Change
When a city experiences a hard rainfall it can cause an ecological disaster. Despite the large stormwater treatment plants in place, the sanitary stormwater sewers can't effectively manage the large quantity of water. So this in turn causes numerous disturbances. While one solution to fix the problem is to make larger treatment plants, perhaps a better solution is found by these cities that are proposing more green technology methods to manage the stormwater runoff.
When excessive water enters the treatment plant is can cause oil, brake dust, heavy metals, and other waste to enter into nearby waterways. When this happens it can cause beaches to shut down, contaminates to enter drinking supplies, and contaminates to enter the food chain.
To prevent the havoc from occurring and being costly to fix, North Carolina State University professor Bill Hunt has suggested recreating or improving the earth's natural filtering system. Which means constructing stormwater wetlands that are modelled on a naturally occurring wetland.
Since nature takes longer to digest and disperse the water, it slows down water entering the ground too quickly. So by mimicking similar environments it will ensure that future rainwater isn't put into the ground too quickly. Instead, it will be released at a pace that can be treated effectively by the underground water treatment plants.
Instead of implementing "sponges" to the landscape in Chicago, the city has focused on managing rainwater through the use of rain barrels. The city spent $6 million over two years in order to provide 123,000 rain barrels to its customers. While rain barrels aren't an effective solution for stormwater runoff problems, they do get individuals thinking about managing the wastewater.
Instead of using rain barrels, North Carolina has decided to implement green streets. The street they renovated in Fort Bragg features 13 sunken "landscape islands" that allow water to enter through a break in the curbing. City engineer Giselle Rodriquez explains that the islands are filled with 3 feet of "expensive dirt mixed with sand and organic topsoil."
By 2036 Philadelphia aims to create green spaces in the city which will help to reduce stormwater pollution in local rivers and waterways by 85%. They currently have made bump-outs in some of their streets (as shown above) and are also offering subsidies to residents that use porous pavers for their driveways and patios since the material is beneficial for reducing stormwater runoff.
Instead of focusing on street improvements or green spaces, the city of Toronto has placed priority on creating green roofs. In 2010 North America's first green roof bylaw took effect for commercial and residential buildings that had more than 20,000 square feet of floor space. Since then at least 400 green roofs have either been built or are in the permitting process. While the green roofs currently seem scarce, they are estimated to be covering the equivalent of approximately 60 NFL football fields and will only continue to expand.