Greening the Capital City’s Rooftops

  • This high-rise green roof in Washington DC required a large crane to lift the soil and gravel onto three floors. (Photo courtesy of DC Greenworks)

Green roofs are increasing in popularity across the US, especially in cities, where
there’s not a lot of space for gardens. Sabri Ben Achour explores the trend in
Washington, DC, where the city government is promoting the practice for it’s
environmental benefits:

Transcript

Green roofs are increasing in popularity across the US, especially in cities, where
there’s not a lot of space for gardens. Sabri Ben Achour explores the trend in
Washington, DC, where the city government is promoting the practice for it’s
environmental benefits:

In Washington, you can see flowers and vegetables growing on top of homes,
businesses, even government buildings throughout the city. DC officials say
Washington has nearly 70,000 square feet of rooftop greenery. Only Chicago has
more.

One big fan of these so called green roofs is a popular small hotel, Tabard Inn, just a
few blocks from the White House.

“There’s about 10 varieties of sedum on this roof.”

Sarah Murphy is giving a tour. She’s a horticulturalist.

“This is a very pungent oregano here on the corner, it looks heavily used.”

The city of Washington pays building owners about one-fourth of the cost of
incorporating greenery on rooftops. One big reason? Rainwater runoff.

Sarah Loveland works for an environmental consulting non-profit called DC
Greenworks.

She says Washington has what’s called a combined sewer system. The sewer
system doesn’t just take in what’s flushed down the drain, but also all the rain
running off roofs and streets.

“If you imagine that our sewage treatment plant has a dam, and the sewage system
combines with the storm water system before the treatment plant.”

So, when there’s a heavy rain, that dam at the sewage treatment plant overflows.

“You have both raw sewage and runoff from the streets going directly into the river
untreated.”

Three billion gallons of it a year, at one point.

The EPA sued the District of Columbia.

The city had to spend $150 million to address the problem. Part of that money goes
to green roof grants.

The green roofs slow down rain water – give it some place to soak instead of just
running off straight down the gutter. The city says roofs in the city prevent a million
gallons of storm water runoff from entering the Potomac River.

The roofs also insulate buildings – especially during the summer. Some studies
show they reduce energy costs by 20-30%. And they reduce the heat island effect in
the city, since they don’t get blisteringly hot like traditional roofs.

Green Roofs even offer some habitat for creatures, like bees.

Sarah Loveland with Greenworks, the consultant agency, says rooftop gardens are
also increasingly popular for growing food.

“Veggies are really popular, herbs are really popular – this is a trend that’s taking off
in the restaurant industry. There’s a lot of buzz around it.”

Blueberries and herbs abound in the rooftop gardens of the Tabard Inn, where Paul
Pell is executive chef.

(sound of celery chopping)

“Yeah, we go up and get whatever we want, so it’s fresh. We just climb out the
window when we need it. Chocolate basil goes with ice cream, nasturtiums go with
soups and salads.”

Washington has an advantage over some larger cities in its promotion of rooftop
gardens because federal law prohibits skyscrapers in the nation’s capital, so most
buildings don’t cast shadows over their neighbors.

As a result, most rooftops are sunny – all they need is greenery to soak up the rays.

For The Environment Report, I’m Sabri Ben-Achour.

Related Links

Dental Offices Adding to Mercury Problem

  • George Washington's dentures. (Photo courtesy of the National Institute of Dental and Craniofacial Research)

Dental offices are producing higher levels than
expected of a toxic form of mercury. Rebecca Williams
reports on the findings of a new study:

Transcript

Dental offices are producing higher levels than
expected of a toxic form of mercury. Rebecca Williams
reports on the findings of a new study:

When dentists remove fillings, most of the mercury in the fillings is
trapped in a filter in the spit drains. But some of it does get through.

Mercury in its simplest form is not as toxic as what’s called methyl
mercury. That forms when mercury is exposed to certain bacteria. Methyl
mercury is very toxic even in small amounts.

Researchers at the University of Illinois say they found much higher levels
of methyl mercury in wastewater from dental offices than they expected. In
fact – they say they were the highest levels of methyl mercury ever reported
in an environmental water sample. And that toxic mercury is eventually
released into the environment.

The findings were published online in the journal Environmental Science and
Technology.

To put this all in perspective – the authors say the amount of mercury
coming from dental offices is really, really tiny compared to mercury coming
from coal-fired power plants.

For the Environment Report, I’m Rebecca Williams.

Related Links

Ten Threats: Bacteria Hits the Beaches

  • Lake Michigan dunes with a power plant in the background. (Photo courtesy of EPA)

If you swim or play on the beaches around the Great Lakes, you’ve
probably heard about ‘beach closings.’ At best, the situation is an inconvenience.
At worst, it’s a serious health risk for some people. That’s because the
beaches are closed due to dangerous levels of bacteria in the water.
Beach closures are not all that new, but Shawn Allee reports… the
science behind them could change dramatically in the next few years:

Transcript

We’re continuing our series, Ten Threats to the Great Lakes. Our field guide through the series is Lester Graham. He says anyone who visits Great Lakes beach is familiar with one of the Ten Threats.


If you swim or play on the beaches around the Great Lakes, you’ve
probably heard about ‘beach closings.’ At best, the situation is an inconvenience.
At worst, it’s a serious health risk for some people. That’s because the
beaches are closed due to dangerous levels of bacteria in the water.
Beach closures are not all that new, but Shawn Allee reports… the
science behind them could change dramatically in the next few years:


(Sound of dog and beach)


During the summer, dogs and their owners usually play together in the
water along this Lake Michigan beach, but today, several dog owners
scowl from the sand while their dogs splash around.


“It’s e coli day … it’s a hardship.”


This beachgoer’s upset, and like she said, e coli’s to blame.


Park officials tested the water the previous day and found high levels of
the bacterium. Missing a little fun on the beach doesn’t sound like a big
deal, but there’s more at stake than recreation.


Cameron Davis is with the Alliance for the Great Lakes, a regional
advocacy group.


“Beaches are most peoples biggest, tightest connection to the Great
Lakes, so when beaches close, they really impact our quality of life in the
region.”


And ultimately, health is at stake too. For a long time, scientists tested
beach water for e coli because it’s associated with human feces. That is,
if e coli’s in the water, there’s a good chance sewage is there too, and
sewage can carry dangerous organisms – stuff that can cause hepatitis,
gastric diseases, and rashes.


Sewage can get into the Great Lakes after heavy rains. That’s because
some sewers and drains can’t keep up with the flow, and waste heads to
the lakes.


For a long time, scientists thought human feces was the only source of e
coli in Great Lakes water, but a puzzling phenomenon has them looking
for other causes, too. Experts say cities have been dumping less sewage
into the Great Lakes in recent years, but we’re seeing more e coli and
more beach closings.


Paul Bertram is a scientist with the U.S. Environmental Protection
Agency. He says, we’re closing more beaches because we’re testing
them more often.


“But I don’t think it’s because the Great Lakes are getting more polluted,
and more filled with pathogens, I think we’re just looking for it more.”


If we’re finding more e coli because we’re testing more often, we still
have a problem. We still need to know where the e coli’s coming from.
Bertram says there might be another culprit besides sewage.


“There is some evidence that it may in fact be coming from birds, flocks
of seagulls, things like that.”


But some researchers doubt sewage and bird droppings can account for
high e coli levels.


(Sound of research team)


A few researchers are sorting vials of water in a lab at the Lake Michigan
Ecological Research Station in Indiana.


Richard Whitman leads this research team. He says, in the past,
scientists could predict beach closings by looking out for certain events.
For example, they would take note of sewer overflows after heavy rains.
Whitman says researchers can’t rely on those triggers anymore.


“A large number, maybe even a majority of closures remain unexplained.
Today, we have closures and there’s no rainfall, may not even be
gulls, and we don’t know why the bacteria levels are high.”


Whitman has a hunch that e coli can grow in the wild, and doesn’t
always need human feces to thrive.


“This is my theory. E coli was here before we were. It has an ecology of
its own that we need understand and recognize.”


The idea’s pretty controversial. It runs against the prevailing theory that
e coli only grows in waste from warm-blooded animals, such as human
beings and gulls, but the idea’s also a kind of political bombshell.


If he’s right, it would mean our tests for e coli aren’t very accurate – they
don’t tell us whether there’s sewage around. After all, if e coli is nearly
everywhere, how can we assume it’s a sign of sewage?


“As a pollution indicator, you don’t want it to multiply. If it’s got an
ecology of its own, multiplying on its own, doing its own thing, then it’s
not a very good indicator.”


Whitman wants us to try other kinds of tests to find sewage. One idea is
to look for caffeine in the water. Caffeine’s definitely in sewage but it’s
not found naturally in the Great Lakes, but until we change our water
tests, Whitman will continue his work. He says we still need to know
how much e coli’s in nature and how much is there because of us.


Environmentalists want the government to keep a close watch on the new
science. They say we can’t let questions about the relationship between
e coli and sewage stop our effort to keep sewage and other waste out of
the Great Lakes.


For the GLRC, I’m Shawn Allee.

Related Links

Golf Course Erodes Support (Part 1)

The Great Lakes boast some of the finest beaches in the country…
and
more and more developers are snapping up lake shore property to build
everything from condominiums to golf courses. But coastline development
presents some challenges and potential risks to the lakes. In the first
of a two part series, the Great Lakes Radio Consortium’s Wendy Nelson
reports on one small community that’s struggling with change: