In a concentrated effort to reduce the volume of stormwater runoff that finds its way into the Willamette River, the City of Portland, OR, has become a leader in developing innovative methods to treat and manage stormwater runoff through the integration of landscape architecture and site design. “Like many jurisdictions, we were notified a number of years ago that we had to manage stormwater runoff to reduce combined sewer overflows and pollutant discharges,” says Tom Liptan, an environmental specialist and landscape architect with the City of Portland’s Bureau of Environmental Services. “That was one of the drivers behind our efforts. Others included the protection of salmon in our rivers and the reduction of pollutants in stormwater discharges to comply with the Clean Water Act.”
Ten years ago, when the city started to look at ways to deal with stormwater runoff, the typical solutions included detention tanks and vaults and stormwater ponds. “These were not viable solutions in our community, as we were 80% to 85% built out,’ says Liptan. “We had to find alternatives, so we asked ourselves, ‘What landscape design elements might lend themselves to locations where we could better manage rain and runoff?’”
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Photo: Bruce K. Ferguson |
| A large installation of Ecoloc block pavement at the Morton Arboretum in Lisle, IL |
The city has creatively converted several locations over the past few years, including the SW 12th Avenue Green Street Project, which was completed in 2005. In 2006, the city won a General Design Award of Honor for the project in the American Society of Landscape Architects (ASLA) Professional Awards competition.
The pedestrian zone of the street was redesigned to sustainably manage street stormwater runoff by converting the previously underutilized landscape area between the sidewalk and the street curb into a series of landscaped stormwater planters designed to capture, slow, cleanse, and infiltrate street runoff.
The project works by diverting the street’s stormwater runoff from the storm drain system and managing it onsite rather than letting it reach the Willamette River. The runoff flows downhill on 12th Street along the existing curb until it reaches a 12-inch curb cut channel that directs the flow to the first of four stormwater planters. Water collects in the planter until it reaches a depth of 6 inches; it can infiltrate the soil at a rate of 4 inches per hour. If the water overflows the 6-inch depth, such as during heavy rainfall events, the excess exits through the planter’s second curb cut and flows back into the street until it reaches the second planter. This scenario is repeated until the water fills the fourth and final planter, at which point it is allowed to enter into the existing storm drain system. However, this is a rare occurrence, as it is estimated that the new stormwater system can handle almost all of the street’s annual flow of 180,000 gallons, and simulated flow tests have shown that the system would reduce runoff during a 25-year storm by 70%.
Because the 12th Avenue Green Street Project was a retrofit, one of the biggest design challenges was finding space for the stormwater planters and working around other streetscape elements, such as on-street parking, existing trees, and existing street lighting.
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Photo: Fred Rozumalski, Barr |
| Drought-tolerant native species function to replace lawn at Minnetonka City Hall. |
“With any retrofit project you always have special concerns and challenges, so my goal with this project was to seamlessly combine stormwater management with all of the uses of the street,” explains Kevin Robert Perry, ASLA, the designer responsible for the project while he worked for the City of Portland. He has since moved to private practice and is a stormwater design specialist with Nevue Ngan Associates, a Portland-based firm that specializes in integrating stormwater management within urban design, site design, and landscape architecture.
“In addition to this project successfully demonstrating how urban design and stormwater management can work together, it also had to be a workable template for future city projects,” adds Perry. “Here in Portland, the success of various ‘green street’ projects goes beyond the public realm, as on the private side we are now seeing developers that are looking for ways to implement what the city has done, but on their own development projects.”
For Perry, having the landscape architect play a lead role in the site design is one of the keys to success in projects such as the 12th Avenue Green Street Project. “It’s really important to have the landscape architect on board very early in the design process,” he explains. “Landscape architects are trained not only to look at the science and aesthetics of working with plants, but they are one of the few professions that can create successful outdoor space in a world full of constraints.”
Bruce Ferguson, Franklin Professor of Landscape Architecture at the University of Georgia and director of the university’s School of Environmental Design, says the City of Portland is doing a great job when it comes to integrating stormwater design into landscape architecture. “We have to end the idea that stormwater management facilities are expected to be utilitarian intrusions on the cities where they are located,” he says. “Cities are supposed to be for people, so we need to bring urban stormwater facilities in line with that purpose. Portland is the city everyone is talking about, and they are doing a great job when it comes to integrating stormwater systems with landscape architecture.”
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Photo: Bruce K. Ferguson |
| Porous pavements retrofitted into an urban alley under Vancouver, BC’s “Country Lane” program |
Ferguson says it is crucial on new development projects to start looking at stormwater management as one of the first steps. “You have to look at stormwater when you are laying out the design. There is no right way or wrong way, but you have the choices in front of you. At various stages in a project, it is a case of looking at the land-use type, the transportation, the site planning, and the materials. The general philosophy is to work with the space you have and to keep water in contact with soil, vegetation, air, and sunlight, beginning at the first possible opportunity and continuing as long as possible. That means, for example, looking at where every downspout discharges and possibly building something in that space, like a rain garden or vegetated swale.”
Ferguson is also a big supporter of porous pavement technology, and he says the use of porous pavement can play a significant role in managing stormwater. “In most urban settings, pavement is two-thirds of the constructed—potential impervious—surface area,” he adds.
Porous pavement is a special type of pavement that, if constructed and maintained properly, allows rain and snowmelt to pass through it, reducing the runoff from a site. Porous pavement can also filter some pollutants from the runoff. It is a subject Ferguson knows well, as he has published a 577-page book on the topic entitled Porous Pavement, and he regularly travels across the country to speak on the topic. He is also an advisory committee member on a Water Environment Research Foundation (WERF) project that is investigating “Successful Integration of Stormwater Best Management Practices (BMPs) into the Urban Landscape.” The two-year project, which is scheduled to wrap up in mid-2007, is evaluating the social, aesthetic, and community aspects that contribute to the success or failure of stormwater BMPs.
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Photo: Moseley Architects |
| Including cisterns in a design allows for water collection and reuse. |
“The purpose of this project is to identify the key factors that influence the success of stormwater BMP project implementation and community acceptance,” explains Jeff Moeller, the senior program director at WERF. “Case studies will illustrate these factors and bring them to life in order to provide guidance to communities developing stormwater BMP programs. Ultimately, the project team will develop a highly visual CD-ROM or Web-based tool to disseminate the results. This information will be of interest to water resource engineers, landscape architects, municipal stormwater managers, public officials, environmental groups, and others involved in stormwater management.”
Moeller says in the past, most of the literature and information that has been developed on stormwater BMPs has focused on the technical design and performance aspects rather than the social, aesthetic, and community factors around which this project is centered.
“By identifying common relationships that influence success, including agency coordination and communications practices, capital and maintenance expenditures, and approaches to public education that raise awareness and public acceptance, this research is expected to be particularly valuable in advancing the state of our knowledge, as well as potentially removing barriers to BMP adoption in some communities,” adds Moeller. “The project may also help end users achieve more aesthetically pleasing and multipurpose BMP designs that provide amenity and benefit to communities in addition to their water-quality functions.”
The project team, panel of experts, and project subcommittee met for the first time in Alexandria, VA, in April 2006, and then again in October 2006 in Dallas at WEFTEC. Leslie Shoemaker of Tetra Tech Inc., a Pasadena, CA–based worldwide provider of consulting, engineering, and technical services, and Jane Kulik of Denver, CO–based Wenk Associates Inc., a provider of a broad range of planning and landscape architectural services, are the co-principal investigators (PIs) for the project, and Martina Keefe of Tetra Tech Inc. serves as the project coordinator. “This project is unique in that it has brought together a multidisciplinary panel of experts in design, engineering, land development, municipal management, and other fields to explore and provide examples of the technical, social, and organizational techniques for successful BMP design and implementation,” says Moeller. “WERF has also assembled a project subcommittee composed of a variety of experts on the topic that provide peer review and oversight to the project.”
For Jane Kulik, the work she does on the WERF project fits in with her day-to-day role at Wenk Associates, where she is a vice president and principal of the company. Founded in 1982, Wenk Associates provides a broad range of planning and landscape architectural services to a diverse group of civic, institutional, and municipal clients. The company is recognized nationally and internationally for embracing both the civic and the natural realms, uniting function, form, and human experience. It is also known for integrating natural systems and processes into urban settings and for transforming degraded landscapes into vibrant public or natural realms.
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Photo: Nevue Ngan Associates |
| Urban design and stormwater management go hand-in-hand. |
“Philosophically, our approach to the management of stormwater is that it must be functional as well as beautiful, and the two should be simultaneous,” explains Kulik. “That means for both new projects and retrofits, the landscape architect needs to be involved from the ground up. We find it is counterintuitive to look at it later.”
Whether working on a new project or a retrofit, Kulik says the form and appearance of the stormwater system can be key to the end result. “If it is done right, a stormwater garden can be a key amenity for the property and a significant part of the ‘experience’ for visitors. Something as simple as an art installation that feeds collected stormwater into the system can help visitors understand that stormwater can be a beneficial resource, that it can be used artfully, and that it can reduce dependence on potable water for irrigation. It is especially important for people to be able to hear, touch, and see the water. Moreover, artfully combining aesthetics with functionality provides a way to get multiple benefits from a single expenditure, which can be an important consideration for a client/owner.”
When it comes to integrating stormwater systems into landscape design, Fred Rozumalski, the lead landscape architect in the Water Resources Group at the Barr Engineering Co. in Minneapolis, MN, integrates “alternative practices based on the model that nature presents. We work with nature and take advantage of the resources rather than treating them as waste products.”
Barr is an employee-owned multidisciplinary engineering firm that serves the Midwest. Its client base includes developers of commercial and residential projects and city and county governments.
“We look at project design from two perspectives,” says Rozumalski. “We look first to prevent stormwater runoff, and second, once stormwater is draining off hard surfaces, we plan for its treatment. On the prevention end, we reduce impervious surfaces as much as possible. That means looking at things like reducing road widths, reducing cul-de-sac size, and creating shared parking areas for adjacent buildings. Once we prevent as much runoff as possible, we look for ways to prevent it from leaving the site. This is done through bioretention, creating rain gardens, or planting a tree canopy that intercepts and evaporates the precipitation.”
Rozumalski points to a project for the City of Minnetonka, MN, that Barr completed in the spring of 2006 as an example of what can be done. “This was a retrofit project for a civic center and complex of other buildings and parking lots,” he explains. “We realigned roads and regraded parking lots and implemented better stormwater solutions at the same time.”
The city wanted to mimic the natural surroundings of the “10,000 Lakes” area while at the same time protect the local creek and adjacent wetlands from large volumes of stormwater. It also wanted to demonstrate sustainable practices to residents and businesses in the community.
“We installed infiltration basins and reduced the lawn areas by 75%, leaving lawn only where it is actively used,” explains Rozumalski. “We substituted trees and shrubs for lawn in a simplified version of a local forest that kept the plantings simple to maintain. We specified tamarack for the wet areas, ironwood for the drier areas, and low bush honeysuckle as an alternative to lawn. That prevented the need for fertilizers, pesticides, and an irrigation system. We also developed a tree canopy over as much of the paved areas as we could so that rainfall is collected on the leaves and then evaporates. This is a good way to reduce the volume of stormwater leaving a site.”
Rozumalski says the city is ecstatic with the results. “They love it,” he says. “They are very proud of the beauty and function of the project and providing an example of how their citizens can protect Minnetonka’s natural resources.”
Bryna Dunn, director of environmental planning and research for Richmond, VA–based Moseley Architects and chair of the US Green Building Council’s Sustainable Sites Technical Advisory Group, says keeping and treating water onsite is an important consideration when developing stormwater management systems. But in addition to natural solutions such as rain gardens, she says Moseley Architects has been including cisterns in a few of its designs as a way to collect and reuse stormwater.
“If we collect stormwater from the roofs of buildings, we are able to save and use that water for irrigation, cooling tower make-up, and flushing of toilets,” explains Dunn. “It is a way of keeping that water onsite rather than just putting it into a pipe and sending it off to become someone else’s problem. Also, when you are using stormwater for these purposes, you are potentially saving on your water bill.”
Moseley Architects specializes in public sector buildings, including schools, and Dunn says in many cases, the stormwater systems can be tied into the curriculum, creating a learning opportunity for the students. “We are currently working on a project for the TC Williams replacement high school in Alexandria, Virginia,” she explains. “They are doing a number of innovative things to make this a high-performance green building, including installing a 450,000-gallon cistern that will supply the school’s irrigation systems, cooling system, and toilets.”
The concrete vault, or cistern, is buried underground in front of the 465,000-square-foot school, and both the runoff from the roof drains and the cooling tower condensate is piped into it. The water will be filtered, cleaned, and tinted with a food-grade dye before being sent back into the school for use.
“Historically, water for things like cooling systems, irrigation, and toilet flushing would come from the drinking water source, so we looked at this opportunity and said, “Why not use this nonpotable source of water instead?’” says Dunn.
Moseley Architects is also working on a building that the company will eventually move into. This historic building in Richmond, VA, was a warehouse and workshop for a truck-mounted hydraulic lift repair center. The architectural firm has purchased the building and is in the process of renovating it into commercial office space.
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Photo: Nevue Ngan Associates |
| A portion of Portland, OR's Green Street Project |
“On this building, we are also planning on including a cistern to collect the roof runoff,” says Dunn. “It will have a green roof, and we will be replacing the hard-packed gravel parking lot with permeable paving, creating rain gardens, and installing biofilters. By doing all of these things, we can slow down the stormwater considerably, and we should be able to reduce the site’s load on the city’s aging combined sewer and stormwater system by at least 60%.”
Michele Adams, a principal engineer with Cahill Associates Inc. in the Philadelphia, PA, area, says looking at how sites manage rainfall naturally before they are developed can help designers and engineers come up with creative solutions for stormwater systems.
“It all begins by understanding how the site works,” says Adams, who is part of a 30-year-old water resources firm with a mix of engineers, scientists, and planners. “You have to look at the rainfall, the geology, and the vegetation, and then design components that replicate how the site worked before it was developed. The process begins by forming a project team that works together right from the start.”
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Photo: Nevue Ngan Associates |
| Lanscaped areas between street and sidewalk capture runoff. |
Adams says the Penn State University Visitor’s Center is a good example of this. “The Penn State project was very much a collaborative effort,” she says. “The architect was Susan Maxman Architects in Philadelphia; the landscape architect was Andropogon Landscape Architecture, also in Philadelphia; and we were the stormwater engineers. The architects fitted the building very carefully into the topography of the site, while the landscape architect worked closely with us to develop ways of creatively dealing with stormwater. This included incorporating rain gardens, vegetative infiltration beds, infiltration trenches, and porous pavement for the parking lots and sidewalks as a means to allow the site to maintain some natural functions.
The most important aspect of this project is that the stormwater is managed where it is generated and that greatly reduces the need for pipes.”
Another project Cahill Associates worked on recently was the kindergarten-to-grade-8 Penn Alexander School in urban west Philadelphia. For this project, Cahill Associates was also the stormwater engineer and worked closely with the Philadelphia Water Department, the University of Pennsylvania, AOL-B Architects, and Olin Landscape Architects in Philadelphia.
“Like a lot of old cites, Philadelphia has combined sewers. When it rains heavily, the sewers fill and discharge a combination of stormwater and sewage to the nearest waterway,” says Adams. “The Water Department has been looking at ways to reduce these overflows by reconnecting stormwater to the land where safe and feasible instead of expressing it to the city’s sewer systems. The goal is to use nature’s designs in our urban management systems, and this was one of the first projects to do this. At Penn Alexander, we accomplished this by taking all of the runoff from the new playground and the roof of the school and directed it to a storage infiltration bed that is located under a new athletic field. A playground with a porous asphalt surface and an adjacent rain garden also catch some of the runoff. All of these things collectively reduce the stormwater burden to the sewers, a significantly less expensive solution than building large, underground storage tanks.”
Portions of Philadelphia’s combined sewer system date to the late 1800s, and, according to Howard Neukrug, the director of the Office of Watersheds for Philadelphia, the system alone may not be adequate for today’s requirements. Its original function cannot always meet the ambitious standards set by the Clean Water Act.
“We have to look at this magnificent infrastructure that was designed and built in the late 19th century—in its time an unparalleled public works vision that resulted in the reduction of cholera and typhoid epidemics, facilitated the industrial revolution, and lay the foundation for the development of Philadelphia as it appears today,” he notes. “To judge these systems against today’s standards is not fair or reasonable. The question is, do we solve our current problems by trying to reinvent the past, or do we come up with modern solutions?
“Today, we face multiple issues that challenge us to find solutions to flooding, combined sewer overflows, and the protection and restoration of our river and stream waterways,” he continues. “Our philosophy is to solve these challenges by looking at our tools and the resources and knowledge acquired 130 years after our original venture. Our modern-day ‘tools’ are designed to integrate land, infrastructure, waterways, and community priorities to develop the optimal solutions that meet our multiple goals. It is our opinion that all of these goals need to be dealt with collectively to manage, in a cost-effective way, stormwater. If we can keep stormwater out of our sewers by using our land or facilities to take on nature’s role while at the same time creating a green community amenity, then we are doing our job. When we can solve flooding or sewer overflow problems by providing kids with a basketball court or a soccer field that is ideal to play on and that at the same time efficiently drains stormwater back into the earth’s groundwater, we have not only improved the environment, but we have also improved the quality of life for the residents of Philadelphia.”
Stuart Echols, Ph.D., an assistant professor in the Department of Landscape Design at Penn State University in State College, PA, says the biggest change we are seeing in stormwater systems is in the way stormwater is viewed.
“In the past, stormwater design has been regarded as a utility, but now we are starting to see it as an amenity,” says Echols. “If we are going to integrate stormwater into the design of the buildings and the landscape, we have to come up with designs that engage, intrigue, and educate. And that means it has to be created at the front door of the building, not in the back corner of the parking lot. The profession is now designing systems that manage the flow rate and the quality of the water. In the smaller flows, we are seeing designs that are approachable, understandable, and touchable. The public can be exposed to the entire process.”
For existing sites, Echols says the biggest challenge is that most of the systems are underground, so we have to look for opportunities to fit new systems in wherever we can. “It is fascinating to walk around an urban environment and start thinking about stormwater systems. You start to see small pockets that are not being used for anything, and you think about ways to retrofit these areas. This can include biofiltration, rooftop gardens, and stormwater gardens. These are all ways to create a playful environment for runoff.”
Echols says we also have to tell the public about the systems and how they work. “The last thing that needs to be done on many of the projects out there is some sort of signage,” he concludes. “Most of the designs are engaging enough to make people curious, and the fact is, people are drawn to water, so we may as well tell them what we are doing.”