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| Philadelphia has become a leader in green water management. Measures include replacing 30% of its concrete roads with porous ones. Photograph: Corbis |
"The city is emerging as a water management leader, investing in green infrastructure to capture water where it falls
Every year storm-water run-off causes nearly 10tn gallons of polluted water to be dumped into America's rivers and oceans. As cities
across the country struggle to comply with federal regulations
surrounding pollution, Philadelphia is emerging as a model of innovation
in water management by opting for cost effective natural solutions to an expensive man-made problem.
Concrete and rainfall
It's
not by chance that Philadelphia has become a leader in green water
management. Two major rivers flow through the city, and historically it
had a vast network of creeks and streams. Over the past 100 years or so
of relentless development, many of these creeks and streams have been
replaced with concrete pipes and sewers, and most of the city's
naturally porous surfaces have been paved over, making it impossible for
rain water to be absorbed where it falls.
As Larry Levine of the
Natural Resources and Defense Council (NRDC) explains: "When we pave
over the earth and prevent water seeping into the ground, we put
barriers in the way of natural processes. Storm water has to go
somewhere. Today, most of it goes into concrete systems."
Unfortunately,
these concrete systems are not always able to accommodate all the storm
water that comes their way. The Philadelphia Water Department (PWD)
estimates that, when all the impervious cover in the city is exposed to
one inch of rainfall, it generates about 327m gallons of storm water.
This first inch of rainfall gathers most of the surface pollutants
before being routed into the city's combined sewage systems. If the
system becomes overwhelmed with excessive runoff, it is designed to
overflow. When it does, you get raw sewage mixed with polluted storm
water spewing directly into the rivers and creeks.
From grey to green infrastructure
A
few years ago, when faced with having to come up with a viable
long-term storm-water management plan to meet their obligations under
the Clean Water Act, the PWD saw an opportunity
to reinsert nature into what had become an unnatural equation. Instead
of opting to expand the traditional grey infrastructure and build more
pipes and tanks to treat waste water, they chose to invest in green
infrastructure to restore nature's ability to capture water where it
falls and treat it as a resource before it ever becomes waste.
When a cost benefit analysis showed the latter option to be far less expensive than the former (around $2.4bn over 25 years for the green approach as opposed to $8bn for the grey), the city became convinced that it was making the right decision.
Managing
water the green way involves a multi-pronged approach, ranging from
distributing rain barrels to residents free of charge and planting
strategically located rain gardens in parks, on curbsides and on
rooftops, to the more challenging and costly task of replacing 30% of
the city's concrete roads and pavements with porous ones.
The
ultimate goal is to minimise the need for large storage tanks and
treatment plants by enabling the water to be captured where it falls.
The PWD's public affairs manager, Joanne Dahme, is quick to point out,
however, that the new green infrastructure is not meant to replace the
old grey infrastructure, but to complement it. "The green approach could
not work without a good traditional foundation. Pipes and sewers are
the backbone of our system, but the green helps the grey do a better
job."
Bills, bills, bills
So far the programme is mostly funded directly by the city's ratepayers, some of whom have not been happy to see their storm-water bills increase.
However, the PWD did not simply institute an across-the-board rate
rise,but switched from a meter-based system to a more equitable system
based on parcel size. This has meant that some businesses, such as
parking lots, which would have had relatively low bills based on water
usage, are now paying much higher rates
based on how much storm water their property generates to the sewer
system. Meanwhile, high rises that do not have a lot of impervious cover
will have seen their rates decrease.
The beauty of the new fee
system is that it incentivises private property owners to retrofit their
sites with green infrastructure. Those who take advantage of the credit
incentives will not just see their rates go down but ultimately as the
city becomes greener and there is less storm water to deal with, rates
will go down for everyone. The new fees will not be fully phased in
until 2014, but Dahme says that business owners facing higher
storm-water fees have already expressed a lot of interest in working
with the PWD to retrofit their properties, and the city is looking at
several cost-sharing opportunities.
Private investment
The
city is also working to leverage private capital to support the
transition from grey to green. According to Eron Bloomgarden, a partner
at EKO Asset Management, who specialises in this area, there are a lot
of investors interested in environmental impact. The key is to develop
compelling financial products for them to put their money to work in.
"We can do for green infrastructure (GI) what the Energy Savings
Corporations (ESCOs) did for green energy. ESCOs were able to encourage
investment by demonstrating the long term energy savings, GISCOs can do
the same thing for green infrastructure."
It's still too early to
determine how successful Philadelphia's efforts to create private
markets for storm water retrofits will be, but the city is seen as a test case.
Philadelphia's Green City, Clean Waters programme is also being closely watched by other American cities for benefits that have nothing to do with cost. Green infrastructure doesn't just give a city a prettier face,
it has also been shown to remove pollutants from the air, lower asthma
rates and other heat related illnesses, reduce heat island effect,
create local jobs and increase surrounding property values. In other
words, going green should be a win for everybody. If this proves to be
the case, then Philadelphia's Clean Waters programme may well be the
model for the future."
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