Posted by Sophie Nichols on Wed, Sep 14, 2022 @ 5:39 AM
Earlier this year, an article published online by editor and writer Melissa Denchak highlighted some shocking statistics coming out of America. Denchak stated that ‘an estimated 10 trillion gallons of untreated stormwater runoff, containing everything from raw sewage to trash to toxins, enters U.S waterways from city sewer systems every year, polluting the environment and drinking supplies… [with] runoff causes significant flooding as well.’ (Denchak 2022).
Denchak described the ‘U.S Environmental Protection Agency (EPA) estimates that upgrading the stormwater and other public water systems will require at least $150 billion in investment over the next two decades.
This problem is not unique to the U.S, it is a problem all over the globe. The question is, how do we address the issues caused by stormwater runoff?
In this article, Citygreen will argue that green infrastructure offers a cost-effective solution to handling flooding and stormwater pollution.
To start, let’s break down the basics.
What is Green Infrastructure?
Green infrastructure encompasses a variety of water management practices, such as planted verges, bioretention pits, swales and other measures that capture, filter, and reduce stormwater. Essentially, green infrastructure replicates natural hydrological processes using soil and plants to slow down, recycle and clean stormwater runoff.
What is stormwater runoff?
Runoff is the product of a rain event causing water to flow into sewers and waterways. With the expansion of our bustling cities and the widening sprawl of our urban areas, there are more impermeable surfaces than ever, changing the intensity of stormwater runoff. According to Denchak, ‘the average city block can generate more than five times as much runoff as a forested area of equal size’ (Denchak 2022).
What is an example of a successful green infrastructure project?
Denchak proposed that New York’s Staten Island Bluebelt was the ‘first and largest green infrastructure project in the U.S.’ A rapid increase in population size saw the Island struggling to deal with sanitary waste and stormwater runoff. The Bluebelt project ‘helped solve these issues by preserving streams, wetland areas, and other drainage corridors (Bluebelts) that use natural mechanisms to capture, store, and filter stormwater’ (Denchak 2022). Nowadays, the Bluebelt comprises more than 14,000 acres and can temporarily hold and filter as much as 350,000 gallons of rainfall.
How does Citygreen implement green infrastructure projects?
Over the past three decades, Citygreen has made significant investments in green infrastructure projects. We learnt early on that mimicking natural systems to manage rainfall, is the most cost-effectively way to deal with stormwater runoff.
An example of a green infrastructure designed that Citygreen has developed is the Strataflow™ system. Instead of a traditional bioretention basin, Citygreen’s Strataflow™ uses an underground structural soil cell system, which delivers a high standard of stormwater treatment with a completely natural look. To any passer-by, what you see is a healthy, flourishing tree surrounded by a grassy verge, but beneath the ground is an advanced WSUD.
This design starts with the Strataflow Kerb Inlet; this device sits in the road kerb alignment, retaining the inherent structure of the concrete kerb. The inlet has a grate (acting as a screen) to stop larger-sized pollutants from entering the system, which inhibits healthy tree growth.
The inlet lets water from the road carriageway flow through the front grate of the drain at a capacity of up to 18 litres/ 5 gallons per second. This allows the inlet to minimise pollutants entering waterways and reduce flood risks by controlling the stormwater flow entering our city’s underground drains.
When the water flows through the street, it enters through the inlet and flows underground. From there, the stormwater reaches the advanced structural soil cell system, where the stormwater is stored, filtered and distributed effectively for the benefit of urban trees and proper stormwater management.
The inlet ensures the water drains down at the correct optimal depth beneath the pavement height. From there, the stormwater reaches the structural soil cell system and the tree’s root system, where the stormwater is stored, filtered and distributed effectively to benefit urban trees and proper stormwater management.
Essentially, Strataflow™ utilises readily available stormwater rather than potable water to irrigate street trees, which improves the vitality of trees and reduces the impact of stormwater on the local environment, all while maintaining a high natural presentation.
Call us Today
Looking for a cost-effective and sustainable stormwater solution? Contact our friendly Citygreen Team today.