Philadelphia to be National Model for Green Infrastructure

Back in 2012 we noted that Philadelphia was embarking on a landmark 25-year, $2 billion urban watershed project designed to transform its outdated stormwater management system into a national showcase for new green infrastructure. Now the city is ready for the next step, a newly announced $5 million urban watershed evaluation initiative that will use Philadelphia as the pilot area.

The whole project is fascinating for any number of reasons, but the overarching narrative is the transformation of urban areas from generators of waste and pollution into dynamic systems that return resources with little or no waste.

From a generator of waste and pollution...

As with the inititial $2 billion, the new funding comes from the U.S. Environmental Protection Agency, which has a formal partnership with Philadelphia's Green City, Clean Waters urban watershed initiative.

In terms of returning resources, the goal is to reduce or eliminate excess sewer outflows that occur during rainfall or snowmelt. Like most older cities, Philadelphia has an outdated sewer system that combines stormwater and sanitary waste. When wastewater treatment plants reach their capacity during precipitation, the combined sewer overflows are shunted directly into local waterways as a matter of longstanding practice, resulting in obvious consequences for water quality and pubic health.

...to a rainwater reclamation showcase.

Conventional infrastructure can address part of the problem, such as new holding tanks to keep excess wastewater until the weather dries out and treatment plant capacity is freed up. However, siting issues, expense and operating costs are often prohibitive.

That's where the new green urban watershed infrastructure comes in. The basic idea is to channel as much precipitation as possible into open ground, where soil and vegetation provide natural filtration.

As for where to find that open ground in a densely packed city, that is part of the challenge. Aside from city parks ,the initiative is also looking at school grounds and other public spaces for opportunities to build constructed wetlands. Replacing surfaces in parking lots with porous surfaces is another good option, and streetscapes may provide additional opportunities.

Evaluating the urban watershed

Clearly, replacing concrete with planted areas calls for a long-term commitment to maintenance, so part of the Philadelphia initiative involves testing different plants, soils and strategies to keep those costs to a minimum.

The new $5 million grant will help this effort along in partnership with the recipients, which are Villanova University, Swarthmore College, Temple University, University of New Hampshire and University of Pennsylvania.

The partners are tasked to evaluate long-term performance and identify early-term benefits, in addition to analyzing the economic success of the initiative.

Benefits of restoring the urban watershed

Aside from reclaiming rainwater and snowmelt, cities like Philadelphia can anticipate additional public health benefits from new green infrastructure.

Philadelphia Mayor Michael A. Nutter sums it up like this:

This forward thinking plan will not only result in better water quality for the city, but it will also provide a multitude of benefits for Philadelphians like cleaner air, revitalized green spaces and even new economic opportunity.

For a glimpse of what this can mean on a more modest scale, check out the urban watershed improvements planned for Bellemeade, a small community in Richmond, Va.

In a neat demonstration of the emerging dynamic between environmental protection, urban revitalization, education, public health and economic development, the Bellemeade project involves transforming a neglected and polluted creek into a multilayered community asset.

Image (altered): elPadawan

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