In their efforts to reduce the pervasive problem of combined sewer overflow, cities all over the country are increasingly turning to a wide category of projects commonly referred to as "green infrastructure." The challenges these projects are designed to address are especially pervasive in older cities, when heavy rainfalls overwhelm antiquated sewer systems and result in untreated sewage flowing directly into waterways. Some of the tools used by green infrastructure designers include porous pavements, stormwater planters, green roofs, and bioswales, which slow the flow of rainwater and trap pollutants at the surface before they can enter the water treatment system.
The whole concept got another boost on Tuesday, when New York Mayor Michael Bloomberg announced it would be a major component of his comprehensive $20 billion flood mitigation plan. These approaches are also proving just as affordable as the so-called "grey" infrastructure of pipes and drains that cities have traditionally relied on, or in some cases even more so.
Portland, Oregon, Washington, D.C., and Seattle are just some of the cities that have pioneered green infrastructure projects. In Philadelphia, the city will spend some $3 billion over 25 years on such infrastructure as part of its Green City, Clean Waters program.
In the Midwest, Indianapolis is leading the way. Stormwater planters and bioswales with native grasses run almost the entire length of the city’s Cultural Trail, a state-of-the-art bicycle and pedestrian route built over the past six years that wends its way for eight miles through the downtown streets of Indiana’s largest city.
Streetfilms took a look at the bioswales recently on a rainy day in Indy. The footage below offers a great look at how they work in action, with water filling up the trenches and then slowly draining off without ever entering the sewer system. The plantings also serve to separate bicycles from both car traffic and from pedestrians along the path. The project as a whole has added 500 trees and eight acres of green space to Indianapolis, and at the same time it's saving the city money in water treatment costs.
It’s a great example of how smarter infrastructure can be incorporated from the start in new street design, yielding a whole host of positive environmental effects.