Green infrastructure is an environmentally friendly technique to manage stormwater and reduce polluted runoff. It uses vegetation, soils, and natural processes to manage water and create healthier, more resilient urban environments.

Green infrastructure can be used to replace more traditional concrete, or “gray,” solutions in some cases. It is frequently being incorporated above gray infrastructure, as part of a “water treatment train” to help reduce stormwater volume, and remove pollutants, taking some of the stress off older infrastructure, extending its useful life. Green infrastructure mimics nature by soaking up and storing water. There is a wide range of techniques which include green roofs, permeable pavement and other surfaces, rain gardens and restored wetlands.

Benefits of Green Infrastructure

The benefits of green infrastructure go beyond handling storm water. By reducing the polluted runoff that flows into rivers and streams, green infrastructure practices play a critical role in protecting water quality. Because many techniques involve the use of trees and other vegetation, green infrastructure improves air quality. It can often lower energy costs by helping to keep buildings and sidewalks cool. Green infrastructure also plays a crucial role in making communities and facilities more resistant to storm damage.

Green Infrastructure for stormwater management is catching on, because it not only helps reduce flooding, prevent erosion, and improve water quality in waterways, but because it improves livability, provides recreational opportunities, and is a positive influence on community health.

Philadelphia’s ambitious Green City, Clean Waters program encompasses the multiple benefits of above the ground solutions instead of burying massive investment underground. Instead of going the traditional route followed by other cities in the past and building miles-long, multi-billion-dollar tunnels to hold storm-water overflows–and then pumping the stormwater back into the sewer system when the rain stops–Philadelphia’s stormwater management plan is based on green infrastructure and offers sustainable solutions that can be seen.

Philadelphia’s plan envisions transforming the city into an oasis of rain gardens, green roofs, treescapes, and porous pavements, which advocates say is cheaper than tunnels and makes for a more liveable, prettier city with higher property values and better community health.


Green City, Clean Waters Promo from GreenTreks Network on Vimeo.

Follow the links below for a series of videos that look at the various aspects of Philadelphia’s program. For more details visit Green City, Clean Waters at


Clean Water, Green Jobs:


Green infrastructure can be perceived as costly, but the case for its cost effectiveness, multiple community benefits, and job creation potential is not mere wishful thinking. From design and installation to ongoing maintenance, there’s a growing niche supporting green infrastructure.

Besides creating new opportunities within existing sectors like landscaping, paving, and building, entire new industries are emerging. And this is only the start…

Green Homes


Urban runoff adds more water to the sewer system than it can handle during flash storms–resulting in polluted water flowing into local streams, rivers, and creeks.

Since residential rooftops account for a pretty significant amount of impervious cover in the City, “greening” homes brings small-scale stormwater solutions to Philly’s neighborhoods through projects like installing rain barrels, rain gardens, and flow-through planters to capture runoff when it rains.

Keeping Water On Site


At first glance, the area surrounding the Waterview Rec Center seems ordinary enough–but in reality, it’s comprised of a number of green infrastructure techniques that keep water out of the storm drains.

During heavy rainfalls, when the city’s combined sewer system can be easily overwhelmed, Waterview’s porous sidewalks, tree trenches, and flowthrough planter manage the water where it falls; that helps protect local rivers and streams.

Porous Pavement


Before roads and parking lots, the majority of rainwater hit the landscape and soaked into the ground, was taken up by trees and plants, and was slowly returned to the hydrologic cycle. Paved surfaces changed all of that and flushed pollution-laden runoff directly into rivers and streams.

Pervious pavement allows stormwater to drain through the surface, mimicking the natural system that once occurred on a site.

Rain Barrels: Doing Your Part


Everyone has heard terms like rainwater recycling, rain gardens, and rain barrels, but many of us average folks tend to think they’re far too complicated and best left to the hard core Greenies that live down the road.

In reality, Rain Barrels are cheap, easy to install, and provide free water for non-drinking use. And best of all, they make areal difference for our local rivers and streams.

Rain Gardens


A rain garden is an attractive planted area that has been designed to collect water that runs off a roof, driveway, or other parts of a property, including area lawns. During heavy rains, they can prevent storm sewer overflows that can end up in our rivers and streams.

Besides being an attractive alternative to manicured lawns, rain gardens add value to a neighborhood and provide important habitat for birds, butterflies, and other beneficial insects.

Stormwater trees


Trees are one of the real “unsung” heroes of stormwater management because they do so much to absorb runoff, and Philly has undertaken an ambitious plan to Plant One Million trees over the next decade to improve cityscapes, air quality, and help get urban runoff under control.

The Water Department is going a step further with its “stormwater trees”, whick look like a typical street tree, but have a unique design to help it manage stormwater even more effectively. These trees are planted in a lower pit, which collects more water, and is filled with soil and stone. The pit stores water, where it is slowly absorbed by the earth.

Green Schools


The transformation of an asphalt schoolyard into a vibrant green space not only controls stormwater runoff, it acts as living classroom and provides green recreation space for local residents’ use.

This model of environmental stewardship features an indigenous woodland forest garden, porous pavement, permeable recycled play surface, an agriculture zone, and trees that provide migratory bird and butterfly habitat as well as much needed shade. Along with its community improvement and learning enrichment goals, the “Greening Greenfield” effort has become a model that is being adapted to other area schools.

Like Philadelphia, the City of Lancaster is taking its combined sewer overflow problem seriously–and like Philadelphia, is using a Green Infrastructure focused approach. For a look at Lancaster’s effort, take a look at this video:


For more information, visit their site, Save It!

To Learn More

If you’d like some light fact-filled reading, interesting case studies, or other material that supports the case for green infrastructure, here are a few resources to get you started:

Visit WREN’s Green Infrastructure Resources page>>

The Pennsylvania Landscape and Nursery Association report, The Return on Investment (ROI) of Green Infrastructure Projects in the Urban Environment estimated the green industry to be a $150 billion economic sector that is projected to grow over the long term. In addition to environmental and economic benefits, the report cites numerous ancillary benefits. here’s one of many interesting highlights: “Recent studies are demonstrating dramatic improvement in human performance and behavior when a landscaped environment is incorporated into hospitals, schools, workplaces and neighborhoods. Access to landscaped environments have been shown to reduce hospital stays for patients, improved the recovery of cancer patients, improve the performance of students in schools, and reduce sick leave usage among office workers.”

U.S. Water Alliance: Barriers and Gateways to Green Infrastructure (38 pg. report) features a survey that outlines barriers to green infrastructure at the local, state and federal government levels, and provides recommendations on ways to address the barriers.



- A Homeowner’s Guide to Stormwater Management (1.74MB PDF)Developed by the Philadelphia Water Department





Green Guide for Property Management Developed by the Partnership for the Delaware Estuary

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