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28th July 2022
...Continued from Part 2

Green streets

A form of sustainable road design, green streets combine various green infrastructure practices to more effectively manage stormwater. Whereas typical roads direct runoff into storm drains, green streets use permeable pavement, bioswales, planter boxes, and other stormwater management techniques to capture, absorb, and filter rainfall where it lands, slashing the amount of runoff that reaches waterways and improving the quality of what does. In fact, green streets can remove as much as 90 percent of stormwater pollutants. In the Watts neighborhood of Los Angeles, a green streets project that began in 2016 has now helped offset nearly 30 million gallons of the city’s stormwater runoff that reaches local rivers and beaches each year.

Green streets offer many other benefits as well. In addition to providing an economical alternative to costly new investments in sewer system infrastructure, they can improve air quality, provide shade, enhance the safety of pedestrians and bicyclists, and beautify neighborhoods. When green streets incorporate additional elements—such as energy-efficient lighting, recycled or locally sourced materials, and improved spaces for walking, running, biking, or public transportation—they are referred to as complete streets.

History of Green Infrastructure

As described in the National Research Council’s definitive report on urban stormwater management, most urban drainage systems evolved in the United States after World War II. These complex structures are based on simple technology: catch basins and pipes that capture water and convey it elsewhere in order to reduce and avoid flooding. Unfortunately, many growing American cities soon discovered a major problem: These systems displaced high volumes of stormwater so quickly that floods weren’t being mitigated so much as moved. To make matters worse, the increasingly nonporous city surfaces were leading to drops in groundwater levels and impacting nearby waterbodies.

The thinking about urban stormwater management started to evolve in the 1970s as landscape architects began placing more emphasis on low-impact development. This entailed greater efforts to develop areas around their natural hydrology, using practices like infiltration via vegetative channels and swales. Architects and engineers were beginning to see a flood-prone area’s natural hydrology not as an impediment but as part of the solution to its flooding problems.

Around the same time, scientists and public health officials began raising the alarm about stormwater’s other hazard: pollution. Studies like the Nationwide Urban Runoff Program, completed in the 1980s, showed that urban runoff contained contaminants like heavy metals, sediment, and even pathogens—all of which water can pick up as it flows across impervious surfaces looking for the lowest ground.

At the start of the 21st century, stormwater infrastructure that was strategically built to allow runoff to infiltrate close to the source became an increasingly popular answer for reducing this pollution. This is when the term green infrastructure was likely coined.

New York’s Staten Island Bluebelt was one of the first and largest precursors to modern-day green infrastructure initiatives. Although it was designed in the 1990s, the Bluebelt’s story began in 1964 with the completion of the Verrazzano-Narrows Bridge linking Staten Island to Brooklyn. While better access to the borough sparked a two-decade boom in residential development, the corresponding infrastructure to handle the increase in sanitary waste and stormwater failed to keep up, resulting in chronic flooding, polluted waterways, and the regular smell of sewage. 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—and quite effectively. Nearly three decades later, the award-winning Bluebelt comprises more than 14,000 acres, can temporarily hold and filter as much as 350,000 gallons of rainfall, and has saved tens of millions of dollars that would have been spent on conventional storm sewers.

Building a Greener Future

Although it wasn’t described as green infrastructure at the time of its creation, the Staten Island Bluebelt demonstrates the sustainable and cost-effective potential of green infrastructure and underscores the significant opportunities that come with investing in similarly innovative projects, both big and small.

Municipal and community leaders are beginning to understand that green infrastructure can deliver numerous economic and environmental benefits—as well as helping to correct age-old planning policies that create social divisions. That means more parks, open spaces, and other amenities can be built in formerly neglected neighborhoods, boosting the health and well-being of everyone.

Indeed, cities across the country are undertaking major green infrastructure initiatives. Take Philadelphia, home to one of America’s oldest sewer systems. The city is investing $2.4 billion to retrofit nearly 10,000 acres of impervious surface (at least one-third of the city’s total that is served by a combined sewer system) to manage stormwater runoff. By 2021, it had exceeded its first target goal and is now preventing nearly three billion gallons of stormwater runoff and sewer overflow annually. Perhaps the most groundbreaking aspect of the program is its competitive grant program to spur the voluntary development of green infrastructure retrofits on private property. The city celebrated the greening of its first thousand acres in 2017 and aims to add another thousand acres every five years.

There are plenty of ways that green infrastructure can be used on a smaller scale as well, including in our own homes. Simple strategies range from the use of disconnected downspouts and porous surfaces for outdoor spaces to the planting of native gardens. Or you can join the no-mow movement.

Federal and local funds available for water infrastructure continue to decline, although state and local governments are stepping up their investments of such projects. The United States maintains its embarrassing D grade in wastewater management from the American Society of Civil Engineers while climate change increasingly rears its ugly head. Altogether, there is simply no better time to look toward more effective, sustainable alternatives to the antiquated and faltering systems that we rely on today.

Modernizing regulations at the national, state, and local levels is a crucial step for driving the use of green infrastructure. In recent years, NRDC has been part of successful efforts to strengthen stormwater permits and regulations in places, including California, New Jersey, and Washington, D.C. Further legislation, incentives, and enforcement across the country—from the EPA, the Department of Transportation, and state and city governments—will be essential for combating stormwater runoff going forward.