Converting dank and dirty alleyways into green infrastructure that helps cities reduce stormwater runoff is no easy task. But more cities across the country are stepping up to the challenge. The green alley movement, which began in Chicago in 2006, has spread to cities including Los Angeles, D.C., Philadelphia, Baltimore, Seattle, Boston, Richmond and more.
For several reasons: According to Chicago’s landmark and now definitive Green Alley Handbook, green alleys “showcase innovative, environmental technologies to help manage stormwater, reduce heat in urban areas, promote recycling and conserve energy.”
Retrofitting alleys with permeable pavement slows the flow of water and in some case enables water to infiltrate into the soil below rather than overflow combined sanitary and storm sewers that can lead to flooding of nearby property, the handbook states.
Additionally, converted alleys can be used by residents and adjacent property owners as outdoor space for urban gardens, sidewalk cafes and farmers’ markets. So it’s good for the earth and good for the neighborhood.
In Chicago, former mayor Richard M. Daley launched the Green Alley Program six years ago as part of his environmental and beautification campaign. Because many of the city’s 1,900 miles (3000 km) of alleys were originally built without a connection to the city’s combined sewer and stormwater system, flooding is a common problem. So the goal became to resurface the city’s alleys—traditionally used for trash pick-up and garage access—with permeable materials that allow water to infiltrate into the ground instead of leaving behind pools of stagnant water or having polluted water flow into Lake Michigan.
Today, under the guidance of Janet Attarian, AIA, Project Director for Chicago’s Department of Transportation, more than 100 green alleys have been installed throughout the city. More are installed annually. And they’re working.
Chicago’s green infrastructure, including its green alleys, diverted about 70 million gallons of stormwater from treatment facilities in 2009, according to a study co-authored by the Society of Landscape Architects, American Rivers, the Water Environment Federation and ECONorthwest.
Other cities have followed suit.
Like Chicago, Richmond, Va., has a combined sewer system and a need to address quantity and quality of stormwater runoff.
Between 2008 and 2009, the City worked to secure grants, get approval from the planning commission and the urban design committee, plan the design, coordinate contractors and specify materials for its first green alley project on 5th Street downtown.
Construction kicked off early in 2010, took three months to complete and cost about $15/sf, says Michelle Virts, Deputy Director of The City of Richmond.
“The first alley took about a year to get going, but the following alleys have been much faster,” she says. “Now that we have a process in place, things will go much more quickly.”
The alleys that followed—made with permeable interlocking concrete pavers—include two residential alleys on St. Christopher’s Lane and Monument Avenue, and a second downtown alley on 12th Street that was completed this summer.
So why these particular alleys?
“We picked our worst alleys,” Virts says. “Those that were filled with lots of trash cans, had bad flooding, and heavy pedestrian traffic. We also chose the two neighborhood alleys to see how the residential use of the space would impact the success of the alley.”
So far, the response from residents has been nothing but positive—they not only appreciate the improved functionality of the alleys, but the look and feel as well.
By choosing pavers that replicate the look of old cobblestone streets, Virts says, “We’ve been able to maintain the historical integrity of our alleys.”
Virts says the City is currently working on the planning and design of two more residential alleys, construction of which she’s hoping will be completed by the end of the year.
“We’ll continue working with the Department of Public Works, which maintains our alleys, to identify alleys that need to be retrofitted,” she says. “It’s still considered a pilot project, but we would like to incorporate these into our budget at some point soon.”
Los Angeles, California
Due to budget cutbacks, Los Angeles struggled to complete its first green alley, but it’s now officially open for business.
The East Cahuenga Pedestrian Alley (nicknamed the EaCa Alley) located in the Hollywood Entertainment District (HED) opened to the public in February this year, but the idea for the massive renovation was first introduced by City Council President Eric Garcetti in the fall of 2008. Garcetti’s motion to make a pedestrian mall out of the run-down alley claimed that it had been illegally gated and used privately by nearby businesses, denying access to the public.
Carl De La Fuente, Project Manager for the City of Los Angeles, says that not only was the alley being used improperly, it was disgusting.
“It looked like a war zone,” he says. “It was basically a trash dump filled with potholes and stagnant water, so the effort just to clean it up was huge.”
The project, which used cutting-edge filtration and permeable interlocking concrete paving systems, cost $790,000 and took the City, working in intermittent stages, just under a year to complete. The space is now home to weekend artists’ and farmers’ markets, sculptures, landscaping, lighting, and outdoor dining areas set up by several restaurants located along the alley.
But green alleys in Los Angeles can do more than support neighborhood commerce, they can save the city money.
The Council for Watershed Health’s Los Angeles Basin Water Augmentation study found that the Los Angeles basin relies on imported water for two-thirds of its water supply. By recharging the city’s groundwater resources through infiltration-based practices (including permeable pavers), the area could recharge 384,000 acre-feet per year. This equates to a dollar value of $310 million saved from the cost of importing and pumping from other sources outside the region.
In the 1920s, less than 5 percent of precipitation in the Los Angeles region flowed to the sea. Today, it’s over 50 percent, and with it flows many pollutants that cause beach closures. When beaches close, tourism drops; when tourism drops, it becomes a loss of revenues to Los Angeles and the surrounding cities.
So Los Angeles has begun a green streets program to encourage rainfall to return to aquifers while improving the urban milieu. There are 26 alleys in the HED all of which are slated for assessment, an effort that began in 2009 and will run through December 2018. As for which one the City tackles next, De La Fuente says there are seven alleys in particular that are in the greatest need of repair, but there are no plans yet in the making.
“After the titanic effort getting the first one completed, all the others will seem easy,” he says.
Washington, D.C.-based Meredith Upchurch, Green Alley Project Manager and LID Team Lead, Stormwater Management Branch, Infrastructure Project Management Administration, would agree that getting the first alley up is the toughest. From the award of funding in 2009 until construction completion, D.C.’s initial three green alley projects took two and a half years to complete, including site selection, design, and construction.
“The biggest challenges were choosing locations and deciding what level of design is needed for the sites,” she says. “For the initial three sites, we chose alleys in poor condition that were scheduled for repaving or were unpaved and had drainage problems.”
Construction on another green alley in the northeast area of the city in the Anacostia watershed—the site of the first three alleys—is slated for later this summer, and seven more alleys in the Rock Creek and Potomac watersheds will start construction in the fall. All of the upcoming alleys will be installed with permeable concrete pavers, pervious concrete and porous asphalt.
Alleys make up almost 2 percent of the total land area in D.C., so addressing runoff from all paved areas to reduce stormwater volume and improve water quality is a primary concern, Upchurch says.
“It just makes sense to do a green alley when we are making needed alley improvements,” she adds.
Not only can a city save money on the treatment and conveyance of water, it may also prevent the city from being fined by the Environmental Protection Agency for exceeding pollutant levels, as directed by the National Pollutant Discharge Elimination System permit program.
While the initial effort to launch a green alley program may be exhausting, the long-term benefits are well worth it.