Solving stormwater problems
Monday, September 28th, 2009
By: Kerry Grens
kgrens@whyy.org
Philadelphia's water department has an ambitious new plan for taking care of the city's stormwater overflow. Engineers and environmental groups say the city is taking an innovative approach — but that it won't go all the way to solving the problem.
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Philadelphia can blame it's flooding problems on old infrastructure that combines sewage and rain into the same pipes. Frequently, stormwater overflows the system, and raw sewage ends up flooding into our rivers. To separate the systems would be prohibitively expensive. So the city has planned to use green technology — such as roof gardens and porous asphalt — to divert storm water from the pipes in the first place.
Brady Russell of Clean Water Action says he's pleased to see the city relying on green technology. But it likely won't eradicate the city's overflow problems.
Russell: If at a certain point we have to have more traditional systems, we don't have another way to do it, but it will hold water back so we aren't having as much nutrient and pollution untreated in our waterways, then we need to do that.
Those traditional systems include underground storage tanks and increased pipe capacity. Marc Cammarata manages the watershed engineers in the Philadelphia Water Department.
Cammarata: The integrated approach doesn't just look at stormwater on the streets themselves. It also looks at restoring our streams and wetland systems, and has a piece of upgrading and enhancements to our traditional wastewater treatment system.
The water department concedes that there will still be overflow issues — but it's unclear how much. Robert Traver is a Villanova professor who studies stormwater management.
Traver: We have bunches of rain gardens and rain barrels and porous concrete and green roofs all over campus that we're studying. And the one thing we're finding: it's more effective than we thought it was.
The $1.6 billion dollar proposal awaits approval from state and federal environmental protection groups. Increases in water bills will pay for the 20-year initiative.
Your stories on this topic are very well done. I’d like to pass on a comment. For Philadelphia, the more important stormwater controls will be those associated with the greening of the city streets, such as vegetated street planters, curb bump-outs, and tree boxes. These are the key elements of greening streets and will be highly visible to the citizens, much more so than porous pavement or a green roof. The controls that include vegetation, includcing green roofs, are the single most important aspect of the City's proposed approach, first because evaporation and transpiration by plants provide "free stormwater removal", and also because the benefits we will achieve beyond stormwater control all accrue from the plants and trees: carbon sequestration and reduction of other greenhouse gases, diminishment of heat island effects and the resultant benefit of human health, increase in propertgy values, etc.