Let it rain
Every year, storm water by the billions of gallons (14, by the most recent estimate) overflows the ancient Philadelphia sewer system, and ends up in nearby creeks and rivers, along with whatever horrible stuff it picked up along the way.
There are several ways to approach this matter. They could create entirely separate systems for sewage and storm water. This would work wonderfully well, but would require digging up most of the entire city and would cost a king’s ransom and then some.
They could dig a monstrous underground tunnel to catch the overflow and then feed it back through the treatment plants. (Which, in turn, would likely require massive expansion of the treatment plants.)
Or they could go in a different direction entirely:
“Instead of figuring out how to manage this pollution, maybe we should be looking at how to prevent it in the first place,” said Howard Neukrug, director of the Office of Watersheds in the Water Department. “Let’s break down some of the barriers against nature and deal with rainwater where it lands.”
The idea now is to “peel back” the city’s concrete and asphalt and replace them with plants — with rain gardens, green roofs, heavily planted curb extensions, vegetated “swales” in parking lots, and mini-wetlands.
Everything from impervious streets to basketball courts would be replaced with paving made out of larger particles that let rainwater flow through and leave no puddles behind.
As distinguished, presumably, from the sort of paving they do here that lets rainwater through and cracks the hell out of the pavement in the winter.
The Urbanophile likes the idea, though he cites one potential problem:
There are certainly challenges to overcome — I hear permeable asphalt can’t be salted, for example, a problem in a region with lots of snow — but technology is getting better every day and where there’s a will, we can find the way.
And the EPA isn’t quite sold on the idea either, although I suspect this is due to Not Invented Here syndrome: the ideas they like the best are the ones they think up.
Philadelphia estimates the cost of this project at $8 per month per residential or commercial water account. If they can pull this off for that kind of money, they deserve a Nobel Prize in alchemy, or something.
McGehee »
14 October 2009 · 10:14 pm
As I recall, in Alaska (a region with lots of snow — or so I hear) there are no surfaces that can be salted (legally). Thus alternatives are used.
Philly might look into said alternatives.
CGHill »
14 October 2009 · 10:35 pm
Poking around this little PDF, I found some slightly different advice:
So maybe the salt isn’t so bad after all.
McGehee »
14 October 2009 · 11:17 pm
Of course, on the Dalton Highway when the (unpaved) surface needs winter maintenance, they apply water.
jenn1964 »
15 October 2009 · 7:34 am
Ask Seattle how well the no salt policy works. Isn’t porous asphalt petroleum based? Wouldn’t it exacerbate pollution problems?
McGehee »
15 October 2009 · 9:01 am
In Alaska’s defense, during the icy months almost everybody is riding on studded tires. The only time I ever skidded out on ice enough to cause an accident was the one winter I didn’t have them.
My car wasn’t damaged that time, but it had just been repaired from when it had been hit by another driver while it sat in the driveway minding its own business.
CGHill »
15 October 2009 · 9:06 am
Asphalt is asphalt. The porosity comes from the process by which it’s applied.
But the usual road goo, washed up by rain, ends up below the road bed, and there’s a barrier to keep it out of the subbase. Theoretically, it’s reduced by 90 percent.
Seattle, I understand, worries about salt in Puget Sound. If there normally weren’t any, I’d worry too.