Chicago has more than 13,000 alleys that total
more than 1,900 miles of area. Those 3,500 acres of alleys consist of enough
impermeable surfaces to equal the paved area at about five mid-sized
airports.
Of course, those alleys didn’t begin as paved
surfaces. But as Chicago grew from a town to a city, most of the gravel and dirt
paths behind its buildings were paved over. Stormwater could no longer soak into
the ground.
Gradually the modern alleys began to cause problems in
wet weather. Rain events that lasted for days overwhelmed the city’s combined
storm and sewer system. Basements of business and residential buildings flooded,
overflow went into the Chicago River, and citizens complained.
Many of the usual solutions would not have been
effective. Connecting sewer mains from the alleys to the city’s sewer system was
cost-prohibitive. Repaving cracked alleys didn’t help. But Janet Attarian,
project director of Chicago’s Streetscape and Urban Design Program in the
Department of Transportation (CDOT), came up with a possible solution to the
flooding.
The Green Alley Program, she explains, was “a response
to flooding in alleys and adjacent property flooding due to improperly graded
alleys, and Mayor [Richard] Daley’s desire to make Chicago the greenest city.
Permeable pavements arose as an innovative method to address these issues
without the need to add new sewer connections and, therefore, increase the
burden on our combined sewer system and exacerbate the problem of basement
flooding.”
The pilot project, with four designs in five
locations, cost $900,000. “The funding came from our regular construction
program sources—not a special source,” Attarian says.
The pilot project was fairly low key. “Just a handful
of people at CDOT—approximately five—were involved in developing the green alley
strategy,” Attarian recalls. “The installations were handled by contractors. No
overtime or additional personnel were required.”
Construction began in the summer of 2006. Each green
alley had high-albedo concrete and either recycled concrete or permeable
pavement (concrete, asphalt, or pavers) as base material. Work crews graded the
surfaces, pitching them so that stormwater moves toward the center of the
alleys. From there, it drains into the existing street sewer system.
Underneath the surfaces are permeable layers: 1 foot
of either gravel or crushed stone to trap water until it soaks into the ground.
Optional inlet structures, also known as infiltration trenches, were also
installed to store runoff until the soil can absorb it.
The Green Alley Program was designed to be more than
just a solution to urban flooding. Its “dark-sky” street lamps reduce light
pollution and direct light downward where it is needed instead of up into
windows to keep residents from sleeping. The street lamps reduce energy cost and
provide a white light that reduces glare and helps people distinguish color at
night.
The high-albedo
concrete reduces the amount of heat absorbed, breaking up the urban heat island
effect. Low-impact development (LID) components, such as bioswales and vegetated
swales were added where suitable. The program’s intent is that citizens can add
more LID features to their neighborhoods in the future.
It was soon obvious that the pilot sites were not only
successful in their locations, but worth repeating in more alleys. Asked what
surprised her about this project, Attarian says, “Three big things.”
The first surprise was “the tremendous response from
the design community and the public at large,” she says. “This project has
proven to be transformational for CDOT and for the local permeable pavement
market. Cities both around the region and around the world have spoken to us
about starting their own Green Alley Programs and trying permeable pavements. I
feel we have started a kind of revolution.”
Attarian’s second surprise was that the program “gave
CDOT the confidence to try many new sustainable strategies, including permeable
pavers in parkways, permeable parking lanes, permeable parking lots with
bioswales, and ground tire rubber in our residential and arterial resurfacing
mix designs.”
Her third surprise was how quickly the program “went
from pilot to policy.” She recalls, “In 2006, we did the first pilots. By the
next year, every alley we built contained at least one of the sustainable
strategies we piloted, and that has been true ever since.”
One factor in the success of the Green Alleys Program
is the way in which it was explained so clearly to the public. The major
component of that public education is a publication titled The
Chicago Green Alley Handbook.
This handbook won a Gold Award in Public
Communications from the Illinois chapter of the American Planning Association.
The American Society of Landscape Architects (ASLA) awarded the 41-page handbook
its Communications Honor Award at both state and national levels for 2007.
Members of the ASLA’s professional awards jury added
this comment along with their award: “Hats off to Chicago! It’s inspiring to see
something this impressive come from city hall. The graphics are so simple and it
communicates beautifully to its intended audience. It would be easy for other
cities to replicate and we hope that they do.”
ASLA-member firm Hitchcock Design Group created the
handbook entirely in-house for its client, CDOT (the municipal department
responsible for LID and sustainable practices). This department, the Department
of the Environment, and the consultant design team all provided input. The
consultant team included Knight E/A (civil engineering), Hey and Associates Inc.
(environmental engineering), and S.T.A.T.E. Testing LLC (material testing).
Hitchcock Design Group was solely responsible for the
graphic design and development and the writing and editing of the text. William
Schmidt oversaw the project for Hitchcock. He was surprised by “the immediate
positive reaction that we received from the city staff and the public. From the
beginning we knew that a public relations piece like this would be critical in
developing staff and public support of the Green Alley Program,” so the
favorable response was gratifying for every Hitchcock employee involved in the
project.
The innovative project and its accompanying handbook
received favorable publicity. “From the feedback we have received and the
success of the program I think the handbook hits a home run,” Schmidt says.
The eye-catching and effective handbook has two major
sections, plus a list of printed and electronic resources for people who need
more information. The first section explains the four different prototypes
constructed as pilot projects. Beginning with the public improvements in the
alley right of way, diagrams indicate clearly what the property owners can
expect to see when the city’s work on the alleys is completed. There are even
polite reminders that during installation both garbage pickup and access to
garages will be temporarily unavailable.
The second part of the handbook covers 11 different
LID measures, including rain gardens, native plants, green roofs, recycling, and
collecting rainwater for landscape irrigation. Property owners can add some or
all of these LID techniques to enhance the environmental benefits of the green
alleys.
These sustainable practices are explained in detail. A
visual key indicates suitability for commercial, industrial, and residential
properties. Cost and potential benefits for each technique are included.
The material about LID measures that property owners
can add helps them buy into the city’s part of the program and understand how
they and their neighbors can collectively strengthen the environmental
protection efforts of their municipal government.
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Photo: Chicago Department of Transportation |
| High-albedo concrete reduces the amount of heat absorbed, lessening the urban heat island effect. |
The reference section contains answers to frequently
asked questions and a glossary of sustainability terms. Readers who want more
information can find it grouped under headings of the various LID measures
explained in the handbook. At least one Web site address for an online
publication is provided for each heading.
The handbook’s final page lists Web sites and
telephone contact information for Chicago’s Center for Green Technology and
three municipal departments: transportation, environment, and water management.
A final reminder lets residents know that they should call the Department of
Transportation or their local alderman when problems occur in their green
alleys.
Written for a general audience unfamiliar with
concepts of sustainable development, the handbook’s tone is reassuring without
being pedantic. Terms are clearly explained. At the same time, the handbook does
not assume prior knowledge on the part of the residents in the green alley
neighborhoods.
The handbook’s consistent style of typefaces,
diagrams, and other elements of graphic design resulted in an attractive booklet
that a citizen would want to keep.
The final draft of the handbook was approved in
January 2007. The initial 2,000 printed copies were distributed to residents and
property owners at public meetings to educate them about alley renovation in
their immediate neighborhoods. Aldermen and other public officials across the
city also received printed copies to generate interest in funding future green
alley projects.
As the Green Alley
Program expands, more copies of the handbook will be printed. It has also been
put online as a PDF file.
The ASLA describes
The
Chicago Green Alley Handbook as
“a user-friendly manual on sustainable design for a general
audience.”
Hitchcock Design
Group’s involvement makes an interesting story. When the project began, Schmidt
had just joined the firm and wasn’t yet as busy as he is now. Hey and Associates
contacted Hitchcock, asking the firm to join in on a response to the city’s
request for proposal (RFP) for the project.
CDOT employees had
received complaints about flooding and drainage problems in alleys. They were
looking for “environmentally sustainable and cost-effective solutions,” notes
Schmidt. He had a grand total of half a day to add concepts for green alleys to
go into the RFP.
Schmidt, a Chicago
resident recalls, “I sketched up a plan and section based on my own alley behind
my house, including permeable paving, high-albedo concrete, and recycled
construction materials. I also included best practices on the adjacent property,
such as rain gardens, bioswales, and native trees and
vegetation.”
Not bad for a
half-day’s work. Several months later, CDOT staff members called Hitchcock and
the other corporate members of the team, inviting them to interview for
assignment of the project. Soon afterward they were awarded the
project.
“Essentially, the
four-hour design exercise became the basis for the green alley prototypes that
were constructed, as well as the graphic principles that communicate the project
goals in the handbook,” Schmidt explains.
Asked about the
most difficult part of creating the handbook, Schmidt says, “Honestly, this was
one of the easiest projects that I’ve had the pleasure of working on, because
the project was so well organized. All the key components of the project were in
place: the client and consultant team knew their responsibilities, and we had
buy-in from the mayor and city staff—both critical in making something like this
happen.”
Second only to
Portland, OR, in the number of green roofs (including the famous one atop its
City Hall), Chicago has a serious commitment to becoming a green city. This
collective consciousness and enthusiastic support from the mayor is an advantage
for any retrofitted project.
Schmidt notes that
his city “has been on the forefront of sustainable design for years. As a
result, the learning curve [for the Green Alley Program] was small, because most
city staff was already familiar with most of these ‘green’ principles to some
degree.”
Prototypes for the
green alleys involve three different permeable paving materials: concrete,
asphalt, and concrete unit pavers. Each type has been used repeatedly. As
Schmidt explains, “One of the components of the Green Alley Program was the
development of guidelines used to determine the most appropriate prototype
design based on site-specific physical and environmental conditions.”
Chicago’s climate, with its extremes of hot summers
and bitterly cold winters, affects any outdoor construction project. “All of the
components of the Green Alley Program—permeable paving, dark-sky lighting,
recycled materials, high-albedo paving, and so on—have been used in projects for
years,” Schmidt says, but “none of them have been combined in a green alley
application in Chicago’s climate.”
With this uncertainty, “It is important to do your
homework up front on these projects to understand how the design and materials
will perform under site-specific environmental and physical conditions,” he
explains.
For the Green Alley Program, he and the other members
of the project team identified and planned for such factors as “the impact of
adjacent land uses, underlying soil conditions, the size of the watershed, the
quality of the stormwater runoff, freeze-thaw cycles, and traffic volume” in the
Chicago urban location.
Another uncertainty existed for the program. “There
was little to no experience in the local concrete and asphalt plants designing
permeable mixes, and paving contractors had no experience with the specialized
installation methods,” he notes.
Of the possible types of permeable pavement, he says,
“Permeable concrete pavers had the longest track record in our climate, but
there were still very few large projects that had stood the test of time that
you could point to.”
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Photo: Chicago Department of Transportation |
| Permeable asphalt in a Chicago alley |
Another immediate negative, he explains, was that
“many of the paver contractors were of the mentality that pavers were a
decorative amenity, and not an integral part of a stormwater management
system.”
To overcome this resistance, “CDOT and the civil
engineer had to work closely with the asphalt and concrete plants and the
installation contractors to design and work with these specialized
materials.”
S.T.A.T.E. Testing of East Dundee, IL, experimented
with the composition of the mix materials for the top layers of the alleys.
Conventional hot-mix binds rock and sand tightly. Liquid asphalt doesn’t allow
stormwater to drain down into the soil. The mix needed to have air voids for
permeability, but the 25% suggested as ideal allowed the asphalt to leak
out.
The solution was adding ground tire rubber to the mix
instead of fibers. This product was not only recycled, but also saved money
because paving contractors did not have to buy special plant equipment to
produce it.
The concrete alleys had to withstand the weight of
garbage trucks, delivery trucks, and other heavy vehicles. S.T.A.T.E. Testing
used aggregates made from hard, solid rock to achieve strengths to withstand
pressures in excess of 3,200 to 3,500 pounds per square inch. That measurement
compares to the strength of standard concrete.
But, Schmidt says, “Even after all the up-front work
it still takes a leap of faith to some degree whenever you’re doing something
that hasn’t been done before. Sooner or later, you reach a tipping point where
you overcome the learning curve and there is a pool of experienced contractors
and material suppliers, and pricing is more in line with traditional
paving.”
CDOT is monitoring the pilot green alleys to determine
which designs and materials perform the best in the Chicago climate. “Future
green alley projects will use this performance data to determine the best alley
prototype design and permeable paving material,” says Schmidt.
Attarian says, “We are monitoring the green alley
locations to see how they hold up to traffic and weather-related wear and tear,
such as snow and ice, and how they maintain their permeability. So far, the
results are very positive.” She notes that the program does not include
measuring stormwater quality or quantity.
As for maintenance, Attarian says, “We are working on
determining what kind of long-term maintenance is required and how frequently we
will need perform maintenance. One of the things we will be doing this year is
testing various cleaning methods and looking at permeability rates both before
and after.”
“From my experience, the sustainable design movement
in America has been a grassroots effort, with local government really driving
the movement through the development of green standards and policies, or through
the creation of incentives for private developers to incorporate these
principles,” Schmidt says. “I think most municipalities are incorporating these
green principles to some degree; however, it doesn’t happen without strong
leadership and commitment.”
He concedes that people who are concerned about the
cost of sustainable design elements in their projects have a valid point.
“Clearly, some of these initiatives can come with an initial higher cost than
using traditional construction materials and methods. However, if planned
carefully, there can be cost offsets that balance out the bottom line.”
For example, he says, “In the case of green alleys,
the higher cost of installing permeable paving was offset by [saving] the cost
of installing a storm sewer with traditional impervious paving. Also, diverting
this water from the municipal combined sewer resulted in a direct savings in
water-treatment cost, as well as savings to adjacent property owners by reducing
basement flooding.”
The long-term view is essential in considering
sustainable design features in a project. “I think when you start one of these
projects, you have to look at the big picture and not just the initial project
cost,” Schmidt says. “With time, the up-front cost will come down as contractors
become familiar with new construction methods and as supply and demand for
sustainable building materials increase.”
The Green Alley Program won a Chicago Innovation
Award, sponsored by the Chicago
Sun-Times and Kuczmarski & Associates. These awards honor
Chicago-area businesses and nonprofit organizations that develop the year’s most
innovative new products and services.
Reaction to the Green Alley Program from members of
the public has been favorable. “The feedback we’ve received from areas where
green alleys were installed has been positive,” Attarian says, accompanied by
fewer complaints about flooded basements.
Schmidt agrees on the public’s reaction. “From the
feedback I’ve received, the Green Alley Program has been well received by the
public. In all cases, the pilot projects reconstructed existing alleys where
there were drainage problems, deteriorating pavement, or both.”
Considering all of the sustainable development
features in the project, he says, “The only negative I’ve heard has to do with
the dark-sky lighting that has been installed. Residents seem to have the
perception that the lighting levels have been reduced.”
He adds, “My own neighborhood association has a ‘green
committee’ that is responsible for green initiatives in the neighborhood. The
first reaction I get after presenting the Green Alley Program is ‘How do I get
one?’”
Asked to compare the Green Alley Program with other
green projects she has worked on, Attarian says, “Due to the tremendous response
we have had to this program, it has been very satisfying. Also, as we continue
to monitor the original pilot alleys, it has proved to be very instructive about
what we need to work on in the future.”
She
notes that the Green Alley Program “has filtered into many of the other projects
we are working on, so this year alone we will have several streetscape projects
with permeable pavers and open-bottom catch basins.”