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Overflowing sewers, caused by intense rainfall, can be one of the most severe ecological problems that a city can face, especially in old cities with inadequate infrastructure. A Smart Solution for this problem, already tested by some cities, is to copy nature and create natural “sponges’ for the excess water.
Hard rain can cause ecological disasters for old or unprepared cities in which sanitary and storm water sewers are combined underground. The large quantity of stormwater flowing over a short period overwhelms sewers and treatment plants, forcing oil, dust, heavy metals and feces into nearby waterways. This can in turn enter the food chain, contaminate drinking water supplies or pollute nearby beaches.
The traditional solution to this threat is to build underground tunnels or tanks to capture excess stormwater. This, however, is a very costly solution. For relatively large cities like St. Louis (whose urban area has more than 2 million inhabitants) such projects can cost close to a staggering $5 billion!
Recently, though, engineers have been finding greener, cheaper and smarter ways to deal with the problem. Contrary to the traditional approach of getting stormwater into the pipe and into the ground as fast as possible, the new approach is to imitate nature, and the earth’ s natural filtering system, which works much more slowly and naturally.
The green solution is to create porous places within the city, to act like a natural sponge for the excess water. In effect, these can be artificial wetlands modeled on natural wetlands. These can include low tracts of land ‘“sometimes entire parks- that can collect and filter water, green streets and green roofs, rain gardens and rain barrels, infiltration galleries or even pavements made from porous permeable material. All of these solutions are designed to capture and hold water until it has either naturally percolated through the soil and been absorbed by plant roots or released into the atmosphere through the plants’ leaves.
The true intelligence of such solutions lies in the fact that the benefits and impact go well beyond resolving the problems created by stormwater. Apart from the obvious aesthetic improvement that they pose, expanses of trees and flowers designed to hold water while it slowly seeps to the ground can naturally filter and clean that water and also provide carbon sequestration (the process involved in carbon capture and the long-term storage of atmospheric carbon dioxide) which helps to slow global warming and combats the higher temperature that are often encountered in urban centers.
Five large and small North American cities: Chicago, Fayetteville, Philadelphia, Oak Creek and Toronto, have started using innovative smart green technology to manage stormwater in this way.
According to Dr. Jennifer Drake, from Toronto University:
You’ re creating urban habitats, so you’ re also making pollinating spaces for bees, and public spaces that are beneficial for mental health.
The original article can be found on Politico Magazine.