Philadelphia's ambitious green infrastructure, clean water plan

The City of Philadelphia announced that it will move forward on a plan to invest $2 billion over the next 25 years on green infrastructure to clean up the city's water.

The plan calls for building green infrastructure like stormwater tree trenches, vegetated bumpouts, porous asphalt, rain gardens, and sidewalk planters. These natural infrastructure projects filter rainwater and allow it to slowly seep back into the ground rather than runoff into waterways, taking pollutants with it.

Storm water runoff and the overflow of combined sewer systems -- where stormwater and raw sewage flow together in the same pipes -- into waterways are two of the biggest problems facing urban water supplies.

While many cities are investing in similar green infrastructure projects, none have embraced these practices quite like Philly, says Larry Levine of NRDC:

Green infrastructure is widely recognized as often the best and most cost-effective way to do the job.  But Philly is the first to embrace these smarter water practices with such enthusiasm, by committing to a comprehensive citywide program that will benefit its neighborhoods and its rivers alike. Cities around the nation should take note.

Under the plan approved today, Philadelphia will transform at least one-third of the impervious areas (think concrete and asphalt) served by its combined sewer system into “greened acres” -- spaces that use green infrastructure like roadside planting strips, rain gardens, trees and tree boxes, porous pavement, cisterns, and other features to infiltrate, or otherwise collect, the first inch of runoff from any storm. That amounts to keeping 80-90% of annual rainfall from these areas out of the city’s over-burdened sewer system.

Levine notes that all cities with combined sewer systems must have similar plans under the Clean Water Act. But Philly is unique because their plan uses mostly green infrastructure rather than expensive holding tanks or more tunnels.

Check out this video to find out what else the city is doing to keep its waters clean:

Photo: LoriHorwedel/Flickr

This post was originally published on Smartplanet.com