Landscaping to Slow Runoff

  • The bioswales are planted with species that are hardy and beautiful, like this snowberry. (Photo by Ann Dornfeld)

Some cities are looking at taking away parking
on residential streets and replacing it with shallow
ditches full of native plants that filter stormwater.
It’s a way to reduce the polluted runoff that flows
into lakes, rivers and the ocean. As Ann Dornfeld
reports, not everyone is thrilled with the idea:

Transcript

Some cities are looking at taking away parking
on residential streets and replacing it with shallow
ditches full of native plants that filter stormwater.
It’s a way to reduce the polluted runoff that flows
into lakes, rivers and the ocean. As Ann Dornfeld
reports, not everyone is thrilled with the idea:

We’re walking down a winding lane lined with maple trees, tall, dry grasses and
evergreens. Bright white snowberries dot the dark branches. It feels like a walk
in the country. But we’re actually admiring a big-city sewer system.

This little valley – a sort of shallow ditch – is called a “bioswale.” Its plants filter
out pollutants that run off the street. And special, thirsty soil helps the water
absorb into the earth. Sections of the street are narrowed to make room for the
bioswales, so some parking along the street is lost. But houses without
driveways get two parking spaces between the swales.

The bioswales have thick layers of native grasses, shrubs and other plants. It’s
kind of a wild, natural look. Debbie Anderson lives on a nearby street. As she
walks by the bioswale she says to her it just looks messy.

“We think it looked nice when it was first built, but it hasn’t continued to
look good, I don’t think. We moved out here because there was no
sidewalks and the streets were wide open and we like that. Lots of parking,
we can have lots of company. This way you can have, what, two people
that can come? That’s it! No. I don’t want it.”

That’s a pretty familiar argument to Bob Spencer. He’s with the City of Seattle’s
Public Utilities office.

“The big thing is the lack of parking. People really get into using these
street right-of-way shoulders as their personal parking spots.”

But not everybody thinks parking spots are more important than doing something
to reduce water pollution. Spencer says the neighbors on this street actually
competed with other blocks to get these bioswales. It’s free landscaping – and
the city even worked with each homeowner to choose plants that would blend
with their existing garden.

Spencer says the city’s traditional method of dealing with stormwater has washed
contaminants into a nearby creek.

“Well, in the surrounding streets around here, we have what’s called ‘gutter
and ditch’ drainage. And what happens is the water runs off the property
and the impervious streets and rooftops. And it enters a ditch and then
goes pell-mell screaming down to our local salmon-bearing creek, Piper’s
Creek.”

It’s not just Seattle’s creeks that are flooded with runoff. Untreated rainwater
flows straight into lakes and the ocean, polluting them. Cities across the country
are looking for ways to deal with toxic runoff like that.

Spencer says Seattle is pioneering
large-scale natural drainage. In other words, the rain is allowed to drain like it
does in the wilderness. The plant roots slow the water so it can absorb into the
earth. That helps prevent flooding. Pollutants like heavy metals, pesticides
and fertilizers are trapped in the soil, and some of them are broken down in these bioswales.

“So we’ve got a little bit more like a forested system in that we have a duff
layer that acts as a sponge.”

Spencer says the city hasn’t tested the water quality of the runoff that eventually
enters the creek. But he says the runoff has been slowed to a trickle.

“It infiltrates and holds and keeps here 99% of that runoff. So that’s a
pretty large flush of water that’s not entering the creek with this system.”

Officials in Seattle’s city government like the green look of the bioswales. And
they help the city meet federal pollution guidelines. City Council President
Richard Conlin says over the course of three bioswale projects, the city has been
able to lower the cost to about the same as conventional stormwater treatment.

Seattle’s newest bioswale system will be at the foot of Capitol Hill. That’s where
seemingly half of the city’s young people live, in blocks full of apartments,
nightclubs and parking lots.

“It’s actually the densest urban neighborhood west of Minneapolis and
north of San Francisco. So it has a lot of impervious surface.”

Stormwater from Capitol Hill rushes off the hard surfaces and down to a lake. So
the city is taking advantage of new development at the bottom of the hill. It’s
planning to filter the runoff through bioswales before it pollutes the lake.

“And once we’ve done that, I think we’re pretty much ready to say this is
the standard from now on.”

Conlin says the city will likely install bioswales in all new developments, and on
streets where the most runoff enters waterways.

He says cities around the country are contacting Seattle to find out how to install
bioswales of their own.

For the Environment Report, I’m Ann Dornfeld.

Related Links

Ten Threats: Rethinking Urban Runoff

  • Everybody's got a gutter... and they're part of the urban runoff problem. Rain picks up dirty soot and other chemicals from roofs and heads into the gutter. During storms, the dirty water rushes down the gutters and down streets into storm drains... and can pollute beaches, drinking water and wildlife habitat. (Photo by Shawn Allee)

One of the ten threats to the Great Lakes identified by experts across the region is nonpoint
source runoff. It’s a catchall category for pollution that’s not being spewed from one identifiable
source. The federal government’s finding that rain washing off concrete and asphalt in cities and
suburbs poses as big a threat to the Great Lakes as waste coming out of a factory pipe. Shawn
Allee has a look at the government’s effort to cut water pollution by remaking the urban
landscape:

Transcript

We’re continuing our series on Ten Threats to the Great Lakes. The Great Lakes Radio
Consortium’s Lester Graham is our guide through the series. Today a look at a broad problem
with no simple solution:


One of the ten threats to the Great Lakes identified by experts across the region is nonpoint
source runoff. It’s a catchall category for pollution that’s not being spewed from one identifiable
source. The federal government’s finding that rain washing off concrete and asphalt in cities and
suburbs poses as big a threat to the Great Lakes as waste coming out of a factory pipe. Shawn
Allee has a look at the government’s effort to cut water pollution by remaking the urban
landscape:


(rain running into a sewer)


Water from a rain gutter is pouring into a nearby storm sewer drain. That protects property from
water damage and flooding. But at the same time, they pose an environmental problem for the
Great Lakes.


Roofs, streets and parking lots are made of hard materials like concrete or asphalt. During
storms, rain rushes off these surfaces into storm drains.


The problem is this: the runoff isn’t pure.


Brian Bell’s a storm water expert with the Environmental Protection Agency. He says rain picks
up pollutants on all those roofs and streets, things such as:


“Antifreeze from cars, motor oil, brake fluid, copper from the brake pads, cigarette butts from
trash, household hazardous waste, pesticides that may be overapplied.”


And for most sewer systems, that’s not the worst of it.


“The problem with storm water is, once its mobilized and goes into a storm sewer system, that
system does not treat the waste, so all of those things go to the local waterway untreated.”


In this region, runoff flows into the Great Lakes, where it pollutes beaches, drinking water, and
wildlife habitat.


To fight this, the EPA’s trying something new. It wants to make hard, urban landscapes softer.
The idea’s to replace concrete and asphalt with more soil and plants. That way, water can sink
into the ground and stay out of storm drains.


But how do you do that?


Well, the EPA’s working with places like the Chicago Center for Green Technology to show people
how. The city hopes residents and developers will use what they see here in their own projects.


(city sounds in)


Grace Troccolo’s guiding a tour of the facility.


First stop?


“Our parking lot is slightly pitched, so all of our rainwater flows off into these vegetated bioswales,
which when I’m not with people in the business, I call ‘ditch with plants.'”

The plants aren’t typical bushes or flowers. They’re mostly tall, prairie grasses native to the
Midwest. Their roots help water seep deep into the ground. The Center has several bio-swales,
and they all keep runoff on site and in the ground.


Another stop on the tour is a 40-foot section of the building’s roof. It’s covered with a matt of
short, tangled creeping plants. Grace explains why they’re here.


“So here we are at our green roof. Again, getting back to our issue of storm water management,
the city would like to see more vegetated surfaces and of course, in the city like Chicago there are
a lot of roof surfaces and so this section of the roof is designed to hold all of the rainwater that
falls on it during a one-inch storm.”


Again, the roof’s vegetation retains water and keeps it out of storm drains. Because of these
technologies, the building is an urban runoff success story.


All told, the Center releases less than half as much water to storm drains as similar buildings do.


The EPA wants the average home or business owner to follow suit, but price might keep that from
happening. Green roofs, for example, are more expensive than conventional ones.


But some observers say the biggest obstacles in fighting urban runoff are political. Stephen
Bocking teaches environmental policy at Trent University. He says the public’s used to pointing
fingers at a handful of big, industrial polluters.


People just aren’t used to seeing every house and business as a source of pollution.


“It’s much more difficult to deal with the problem when you’re talking about millions of separate
sources. People can’t just say well, it’s the job of industry or the job of the government to deal with
it. It’s the job of everyone to deal with it in some way.”


In other words, we’re all to blame.


Every new building in a city, or home in a subdivision, creates more hard surfaces, such as new
driveways, new parking lots and new roofs.


“It’s pretty hard to deal with a form of development which is intrinsic to our way of life. It involves
thinking about how we live our lives and how design and build our cities.”


Bocking says the EPA’s plan might not be enough to make up for all the roads and other hard
surfaces we’re building. He says, to succeed, we’ll need to change how we develop land.


There’s not much political support to stop that kind of development right now, so for the time
being, hard surfaces will continue to win out.


For the GLRC, I’m Shawn Allee.

Related Links