Green Infrastructure to Build Green Communities

Katie Maginnis for TEI

With the implications of climate change and the rising price of oil, many architects are embracing the idea of “green building”. Jack Ahern, Professor of Landscape Architecture and Regional Planning, has been developing a theory of landscape urbanism based on green infrastructure practices.

As Ahern explains, “The current urban landscape is an expression of the traditional approach,” with designs based primarily on engineering and little regard for environmental concerns. To make a city more “green” according to Ahern, the infrastructure of the city must be examined. Every city has functional systems such as transportation, water management, and waste removal. “To determine how ‘green’ these systems are,” he says, “we need to look at how many ecosystem services they provide.”

For instance, a natural wetland area may provide several services at once – nutrient regulation, flood control, wildlife habitat, and recreational areas. The idea is to create manmade structures that mimic natural systems. With this in mind, Ahern has been designing a project called the Walden Passage. The proposed structure would consist of a small bridge over Route 2 in Concord, Massachusetts where both wildlife and humans could safely cross the highway. While the main project goal is to lessen the negative effects of habitat fragmentation on wildlife, it may also provide a valuable service to the community.

A substantial number of folks are attracted to the area because of its association with the transcendentalist movement. However, Route 2 creates a physical barrier between Walden Pond and the rest of Concord, making it difficult for residents to connect with nature. If the town chooses to build this structure, Ahern says, “People could have a 21st-century solution to a 20th-century infrastructure problem, and thereby experience an important 19th-century philosophy.”

A structure like the Walden Passage may be a feasible way to “green” a suburban town, but greening a city like Chicopee, where space is more limited, is more of a challenge. Along with students from his landscape architecture class, Ahern is quickly generating ideas. The first step in “greening” a city involves assessing the most serious problems with the existing infrastructure. In Chicopee, this means tackling the issue of combined sewer overflows. During heavy rains, almost 100 percent of the stormwater in the city is wasted as runoff that flows into the sewer instead of infiltrating the ground. When this happens, Ahern explains, “it overloads the system and doesn’t recharge the groundwater, so it’s a double-whammy for streams.”

Fortunately, Ahern and his students have a green solution. “It’s not rocket science,” he says, “Just add more trees.” The trees will intercept water as it falls and direct it to the base of the trees where the water can infiltrate the ground rather than overloading the sewer system.

In addition to increasing the urban tree cover in Chicopee, Ahern is investigating the use of green roofs and rain barrels. Both of these techniques help to reduce runoff, and can redirect the water so it can be recycled into the ecosystem by plants. Furthermore, small gardens planted near these structures can enhance the neighborhood with visual beauty, improve air quality, and provide additional wildlife habitat.

“I like the analogy of a toolbox,” he says. “The green roof is a hammer, and the rain barrel is a saw. The challenge is matching the tools to the place, and integrating it into a system.” For Ahern, an important part of this task is reaching out to the community. “Green infrastructure becomes a sustainable, identifiable, memorable part of the community, just like the main street or the town common,” he says.

When designing green projects like those in Concord and Chicopee, Ahern strives to create structures that provide multiple services to people and ecosystems alike. As he explains, “If you can do this, and build a broad coalition of support – the sewer people, the bird people, the recreation department, the schools – then it sounds to me like a nice example of green infrastructure applied to the real world.” Ahern’s future plans include a book project on international examples of landscape urbanism as a means of creating more sustainable cities.