Today our world faces an immense amount of challenges that engineers are trying to solve everyday. One of these issues happens to be all around us. It is the environment in which we live and the infrastructure that makes life possible. We take many of these amenities for granted such as the streets we drive on, the roofs over our heads, the pipes that supply us with fresh water, and even the landscaping in our own backyards. All these, however, play very important roles in dealing with water drainage, and providing communities with clean water. On the contrary, they do pose problems that engineers need to solve. This can be achieved by a means of green infrastructure, which utilizes landscaping to greatly improve many urban environmental problems. Green infrastructure is, for the most part, cost effective and can be used in numerous ways to replace and improve conventional urban infrastructure. I believe if engineers devise ways to incorporate green infrastructure into every urban setting, many of the environmental problems we face today will greatly decrease.
Green infrastructure, according to the article Green Infrastructure Rising, is “… the interconnected network of open spaces and natural areas—greenways, wetlands, parks, forest preserves, and native plant vegetation—that naturally manages storm water, reduces the risk of floods, captures pollution, and improves water quality” [1]. This type of infrastructure is becoming more prevalent in cities and urban neighborhoods all across the world because it allows for better storm drainage, cleaner water, nicer landscapes, and it controls the higher temperatures experienced within cities [2]. Green infrastructure, including permeable pavement, green roofs, rain gardens, bioswales, strategic tree planting, and landscape-oriented drainage features, are now required by some cities to be incorporated into all new building projects [1]. The conventional methods of infrastructure in communities include impermeable pavements, concrete gutters, sewers, and retention basins. All of these modern infrastructures increase the amount of pollution caused by storm water runoff [1]. Also, they are not especially efficient in removing the water. An article from CEnews.com states that, “Traditional storm water management systems are designed to move water off a site as quickly as possible. This can lead to increased pollution, flooding, erosion, and other environmental problems” [3]. Additionally, the pavement on the roads and roofs of buildings in cities are a big part of the temperature increase seen in urban environments. With green infrastructure, the risk of flooding decreases because it manipulates the landscape and other natural resources to soak in the water and pollutants that may reside in it, instead of just quickly dumping it somewhere else such a river or creek [2]. It provides for cleaner, more livable neighborhoods and cities with slightly cooler temperatures, and increases the value of living [1].
There are many types of green infrastructure, however, permeable pavements, rain gardens, bioswales, and green roofs solve some of the biggest problems in urban environments. Additionally, they require low maintenance and, for the most part, are cost efficient.
Permeable, or porous, pavement can include concrete, asphalt, and pavers. It allows for water and pollutants that leak out of cars to seep through its pores and into the ground. Initially, the water flows through the pavement. It then gets filtered through a bed of stone below the pavement before it is released back into the soil below where it becomes groundwater. The permeable pavement looks exactly like impermeable pavement, but it has small holes that allow for filtration. Unlike impermeable pavement, permeable pavement will not release large amounts of runoff. In fact, its success is so great that companies with large parking lots made of permeable pavement do not even need to construct retention basins or drainage systems because the storm water is naturally soaked into the ground [4].
Rain gardens are a natural way of collecting unwanted storm water. According to the article The Ins and Outs of Stormwater Management, “A rain garden, or bioretention facility, is a landscaped collection of native plants, placed in a shallow depression that captures runoff from impervious surfaces such as streets, driveways, and rooftops. The soil and plants filter out nonpoint-source pollutants, giving the water a chance to slowly infiltrate the ground and recharge aquifers rather than running off into the storm system” [4]. Rain gardens beautify the landscape while retaining storm water. The water and pollutants it carries are deposited in the rain garden where it either increases the groundwater recharge, or the plants and vegetation will soak it in [5]. Since the water is deposited directly into the rain gardens, there is no need for storm drains. They can withstand large amounts of water at a time. Therefore the risk of flooding greatly diminishes [5]. Similarly, bioswales are natural water retention systems that reduce the need for drainage systems and other concrete structures. They are mostly used as subtle landscapes in parking lots. The there is no curb between the bioswale and parking lot, allowing the storm water to drain directly from the pavement to the bioswale where the water is naturally soaked into the ground [6]. Rain gardens and bioswales do need to be maintained, however, it is usually minimal.
While many people think the use of green roofs has just begun within the last few years, it has been successfully used in Europe for about two decades [6]. Green roofs provide for the absorption of storm water and cleaner air. They provide more usable green space in cities and greatly improve energy efficiency in buildings and households. Additionally, green roofs are a great source of insulation and reduce the high temperatures in urban settings [7]. “This is the quality that makes green roofs so effective for storm water management. By absorbing water quickly and then releasing it gradually, the intensity of runoff during a storm can be tempered” [7]. One surprising fact about green roofs is that they are less likely to leak than a shingled roof, and if they do leak, the repairs are usually fairly simple.
There have been many studies done that show the effectiveness of green infrastructure. The article Green Infrastructure Rising found that “Consistent evidence from pilot projects shows that green infrastructure can capture, retain, infiltrate, or evapotranspirate 90 percent or more of the rain from typical storms delivering an inch or less of precipitation. This is crucial because the majority of runoff pollutants are carried in the first half-inch to one-inch ‘first flush’ of precipitation” [1]. Studies also show that 30 to 90 percent of runoff pollution is retained in green infrastructure [1]. Moreover, the article Storm Water Management, Green Roof Style states that “A modeling study found that green roofs on 20 percent of buildings over 10,000 square feet could add 23 million gallons of storage and reduce outflow to sewers by 300 million gallons per year” [7]. Major cities throughout the country are incorporating green infrastructure to enhance their urban environments including Philadelphia, Chicago, Washington, D.C., Portland, Kansas City, and Seattle [1].
Green infrastructure can solve many urban environmental issues in our world. I feel that if we start incorporating green infrastructure into society now, we will greatly reduce urban environmental problems like storm drainage, pollution, floods, poor energy conservation, and increased temperatures. This will also make cities more pleasant places to live and improve our quality of life and ecosystem for present and future generations. It is now up to engineers to incorporate green infrastructure into our everyday lives.
I would like to thank my Engineering 0011 professor, Dr. Vidic for giving me guidance with this paper and the librarians for their guidance in finding the proper resources. I would also like to thank my roommate, Erik Dirkmaat, for helping me with different problems that arose and my parents, Jim and JoEllen Bell, for proofreading my paper.