WHAT IS GREEN INFRASTRUCTURE?
Section 502 of the Clean Water Act defines green infrastructure as "...the range of measures that use plant or soil systems, permeable pavement or other permeable surfaces or substrates, stormwater harvest and reuse, or landscaping to store, infiltrate, or evapotranspirate stormwater and reduce flows to sewer systems or to surface waters."
By relying on plants, soil, and natural systems to manage rainfall runoff, green infrastructure tackles urban water woes and boosts climate resilience." |
Green infrastructure (GI) refers to systems that are built alongside nature and are useful when it comes to managing natural and anthropogenic related issues (American Rivers, 2019). GI can be implemented to assist with stormwater management, especially when it comes to regions that are often flooded. These systems are seen as alternatives to traditional methods that typically handle stormwater management as they are built in a manner that causes minimal impact to the environment.
Generally, traditional gray infrastructure collects and conveys stormwater from impervious surfaces, such as roadways, parking lots and rooftops, into a series of piping that ultimately discharges untreated stormwater into a local water body, whereas green stormwater infrastructure is designed to mimic nature and capture rainwater where it falls.
Through mimicking the natural hydrological processes and using natural elements such as soil and plants to turn rainfall into a resource instead of a waste, GI increases the quality and quantity of local water supplies and provides myriad other environmental, economic, and health benefits—often in nature-starved urban areas.
Generally, traditional gray infrastructure collects and conveys stormwater from impervious surfaces, such as roadways, parking lots and rooftops, into a series of piping that ultimately discharges untreated stormwater into a local water body, whereas green stormwater infrastructure is designed to mimic nature and capture rainwater where it falls.
Through mimicking the natural hydrological processes and using natural elements such as soil and plants to turn rainfall into a resource instead of a waste, GI increases the quality and quantity of local water supplies and provides myriad other environmental, economic, and health benefits—often in nature-starved urban areas.
TYPES OF GREEN INFRASTUCTURE
Green infrastructure can be used on different scales, from the house or building level, to the broader landscape level.
On the smaller end of the scale, i.e local level projects, green infrastructure practices include rain gardens, permeable pavements, green roofs, infiltration planters, trees and tree boxes, and rainwater harvesting systems.
At the largest scale, the preservation and restoration of natural landscapes (such as forests, floodplains and wetlands) are critical components of green infrastructure.
While there are many forms of GI, the most commonly used for stormwater are listed below.
On the smaller end of the scale, i.e local level projects, green infrastructure practices include rain gardens, permeable pavements, green roofs, infiltration planters, trees and tree boxes, and rainwater harvesting systems.
At the largest scale, the preservation and restoration of natural landscapes (such as forests, floodplains and wetlands) are critical components of green infrastructure.
While there are many forms of GI, the most commonly used for stormwater are listed below.
- Green and Blue Roofing: Green and blue roofs are a type of green infrastructure that is designed to provide stormwater detention on the roofs of buildings. Green roofs are roofs where the surfaces of buildings are partly or completely covered with vegetation while blue roofs use orifices and weirs on top of a flat roof to slowly release stormwater. Green and blue roofs help control the discharge rate of rooftop runoff by retaining water on the roof of buildings for heavier rainfall events.
- Porous Pavement: Porous pavements are similar to regular concrete and asphalt but are made without fine materials. They consist of a layered system of stone that allows stormwater to be stored and slowly seep into the ground below. The idea behind porous pavements is to allow some stormwater drainage to occur in areas that would otherwise require drain and pipe systems.
- Rain Gardens: A rain garden is a garden of native shrubs, perennials, and flowers planted in a small depression, which is generally formed on a natural slope. It is designed to temporarily hold and soak in rain water runoff that flows from roofs, driveways, patios or lawns. Rain gardens are effective in removing up to 90% of nutrients and chemicals and up to 80% of sediments from the rainwater runoff. Compared to a conventional lawn, rain gardens allow for 30% more water to soak into the ground.
- Swales and Bioswales: Swales are low lying depressions in the ground that help pool stormwater and allow it to infiltrate into the ground naturally. Bioswales that are planted with vegetation are especially good at this because because the plants assist with filtering pollutants and absorbing rainwater. They are great options due to their low cost and attractive nature.
- Retention and Detention Basins: Stormwater basins are a large depressions in the ground that collect water. Retention basins hold water permanently, while detention basins hold it temporarily. They are especially good at managing stormwater near large residential and commercial developments due to their large size and holding capacity.
- Rain Collection: Rain barrels, rainwater tanks, and dry wells are all methods of stormwater collection and storage. Rain barrels tend to be the cheapest and least invasive option (Alu-rex, 2015). Additionally, rainwater tanks can be implemented above or below ground, and are used for large rainwater storage (Tanks, 2018). Lastly, dry wells are underground filtration systems that if installed improperly can be damaging to the environment, and tend to be used more by government agencies than by private owners (EPA, 2016).
As of October 25, 2019, NJDEP adopted amendments to N.J.A.C. 7:8 “to replace the current requirement that major developments incorporate nonstructural stormwater management strategies to the ‘maximum extent practicable’ to meet groundwater recharge standards, stormwater runoff quantity standards, and stormwater runoff quality standards, with a requirement that green infrastructure be utilized to meet these same standards” (Adoptions Amendments, 2020).
The New Jersey Stormwater Best Management Practices Manual lists types of GI and their applicable uses in New Jersey, as well as how to implement them.
The New Jersey Water Bank, a partnership between the NJDEP and the New Jersey Infrastructure Bank (I-Bank), provides low-cost loans and other funding for a variety of environmental infrastructure projects that provide a water quality benefit as well. Eligible projects include bioswales, stormwater pump-outs, porous asphalt or concrete, green roofs, cisterns, and street tree trenches. NJ Water Savers offers rain barrel workshops and is a great resource for other green infrastructure information.
The New Jersey Water Bank, a partnership between the NJDEP and the New Jersey Infrastructure Bank (I-Bank), provides low-cost loans and other funding for a variety of environmental infrastructure projects that provide a water quality benefit as well. Eligible projects include bioswales, stormwater pump-outs, porous asphalt or concrete, green roofs, cisterns, and street tree trenches. NJ Water Savers offers rain barrel workshops and is a great resource for other green infrastructure information.
REFERENCES
Alu-rex.(2015). 5 Different types of rain barrels. Retrieved from https://www.alu-rex.com/blogue/en/types-rain-barrels/
American Rivers.(2019).What is green infrastructure.Retrieved by https://www.americanrivers.org/threats-solutions/clean-water/green-infrastructure/what-is-green-infrastructure/
Environmental Protection Agency.(2016).Stormwater drainage wells. Retrieved from https://www.epa.gov/uic/stormwater-drainage-wells
Rainwater Tanks Direct.(2018).Tanks.Retrieved from https://rainwatertanksdirect.com.au/small-tanks/
American Rivers.(2019).What is green infrastructure.Retrieved by https://www.americanrivers.org/threats-solutions/clean-water/green-infrastructure/what-is-green-infrastructure/
Environmental Protection Agency.(2016).Stormwater drainage wells. Retrieved from https://www.epa.gov/uic/stormwater-drainage-wells
Rainwater Tanks Direct.(2018).Tanks.Retrieved from https://rainwatertanksdirect.com.au/small-tanks/
By: Angelique Wanek & Dana Kelly, last published December 18, 2020