Innovative Stormwater Design: The Role of the Landscape Architect

As Mike Breedlove, landscape architect and head of Breedlove Land Planning in Conyers, GA, likes to say, “The role of the landscape architect is to successfully marry mankind to nature.” His statement is even more succinct than the description used by the American Society of Landscape Architects (ASLA), which highlights how landscape architects use a comprehensive working knowledge of architecture, civil engineering, and urban planning to “design aesthetic and practical relationships with the land.” This integrative function of landscape architecture makes the profession seem a natural spawning ground for the innovation needed to successfully meet the considerable challenges posed by stormwater-related pollution and erosion.
     
At a time when stormwater regulation is tightening nationwide under the imperatives of EPA’s National Pollutant Discharge Elimination System (NPDES) Phase I and the newly implemented Phase II, the need for effective and economical solutions becomes ever more urgent. Because the NPDES Phase II final rule permitting requirements, published December 8, 1999, pick up where Phase I left off, virtually every municipal jurisdiction–and the entire construction industry–will feel the pinch if it hasn’t already. While the Phase I rule has already been implemented–covering cities operating municipal separate storm sewer systems (MS4s) with populations of 100,000 or more, construction sites 5 ac. or larger, and 10 categories of industrial activity–the Phase II rule now includes cities with MS4s serving populations less than 100,000 and construction sites ranging in size from 1 to 5 ac., and also ends the Phase I temporary exemption for municipally operated industrial activities.
     
Since water integrates all landscapes–urban and nonurban, no matter what the land use–and its integrity is essential to the welfare of humans and the environment alike, one would think that professionals dedicated to the harmonious integration of human life with the natural world would be heavily represented at the forefront of stormwater pollution prevention. In truth, however, while landscape architects cannot be expected to respond in droves–specializing in stormwater is in some ways analogous to physicians specializing in cardiology–the profession’s interest in site design for water quality is only now coming of age. For most of the 20th century, generally speaking, stormwater management was under the charge of engineers throughout the country who followed a standard model of conveyance technology based largely on the original infrastructure of America’s oldest cities in the Northeast. Currently, innovative stormwater design as a subspecialty of landscape architecture is the mission of relatively few practitioners. Nonetheless, there are unmistakable signs that the best and brightest innovators have set in motion a revolution in the very concept of stormwater and what to do with it. Rather than a nuisance, these hydrologically smart specialists view stormwater as a resource; they seek to work with the hydrologic cycle rather than against it, attempting to mimic predevelopment hydrology to the greatest extent possible. According to these agents of change, this moment in the evolution of landscape architecture has enormous potential, not only for landscape architects themselves, but in terms of the contributions they can make. What follows can only be a broad outline, tracing the roots of this emergent trend, its shape and scope, places and situations where innovation can flourish, and roadblocks to innovation and what can help overcome them.

The Historical Context

Landscape architecture’s part in water-sensitive design is a story of fits and starts. According to Robert France, assistant professor of landscape ecology in the Department of Landscape Architecture at Harvard University’s Graduate School of Design, “The profession certainly started well. Frederick Law Olmsted’s Emerald Necklace in Boston [a linked series of public parks] might be the world’s most famous urban water treatment wetland, designed to be so beautiful that few people would guess that it’s an artificially constructed system.” In particular, the Back Bay Fens segment, approved by city council in 1877, was designed to solve serious drainage problems in the tidal swamp, noxious with sewage and subject to frequent flooding. Olmsted built tidal gates and a sewage interceptor and planted wetlands vegetation to create a temporary stormwater storage basin. The Fens proved that landscape architects could use inspired engineering to integrate the functions of nature and people harmoniously. It was a brilliant multifunctional design, with bridle paths, walkways, canoeing, and park drives in addition to sanitary and flood control features. France also notes that the very first watershed management plans were done in the Massachusetts area by landscape architects.
     
Despite such a stunning start, France states bluntly, “Landscape architects next designed gardens for rich folks and lost their edge.” Money for public projects to be enjoyed by all social classes was not forthcoming. Soon the Depression and World War II took their tolls on the field. It wasn’t until the 1960s and ’70s that the next flush of interest in stormwater design occurred, with a new champion – Ian McHarg – whose groundbreaking work, Design with Nature, has been deemed the most important book on landscape architecture in the 20th century. “In that book the whole idea of water management and land-use planning came to bear,” states France, “and computer-map overlays were laid out,” spurring the development of geographic information systems.
     
A flurry of innovative design followed, including two landmark residential developments featuring open drainage systems. One is The Woodlands, a “new town” north of Houston, TX, with ecological planning by the Philadelphia firm of Wallace, McHarg, Roberts & Todd. The Woodlands lies on a flat, forested, 20,000-ac. coastal plain site with significant areas of poorly drained soil. Begun in 1971, the design aimed to maintain the natural hydrologic equilibrium by using existing natural features (ponds, creeks, permeable soils, trees, and other native vegetation) enhanced by constructed ponds, basins, berms, impoundments, and lot-line swales. The first phase of development, Grogan’s Mill, proved especially successful in providing effective stormwater control while maintaining the water table, increasing base flow, preventing erosion and siltation, maximizing recharge, and protecting natural habitat. Original cost analyses showed a savings of more than $14 million over conventional gutter-and-pipe engineering. A three-day, 13-in. rainfall (with 4 in. falling in one hour) occurred shortly after opening, yet no flooding occurred and surface water receded within six hours. The other prominent example of that era is Village Homes, a subdivision designed by Robert Thayer and colleagues for developer Michael Corbett in Davis, CA, begun in 1975. Controversial for its communal style and solar-energy emphasis, the development has as its most impressive aspect site-sensitive open drainage. Percolation ponds, networks of swales, and check dams drain an extensive greenbelt system, with drop inlets serving only as backup for overflow from retention ponds. The subdivision can entirely absorb a 10-year storm on-site.
     
Whatever the reasons, concern over environmental issues faded somewhat from public awareness after the 1970s. In spite of remarkable achievements, says France, landscape architects in the ’80s “lost it again. A variety of other professionals stole their thunder. But now they’re just at the cusp of reinventing themselves once more.”

What Is Called Innovative?

Porous turf
Walkway made of porous turf reinforced with “Turfgrids” fibers

Harvard’s Department of Landscape Architecture observed its centennial anniversary last year as the oldest educational program in landscape architecture in the Western Hemisphere. Felicitously, part of the yearlong celebration was a two-day international symposium organized by France in February 2000, entitled “Water Sensitive Ecological Planning & Design.” The list of presenters represents a veritable who’s who of people on the cutting edge in watershed management and stormwater concerns. (Anyone who couldn’t attend can catch up on the proceedings by reading detailed abstracts of more than 45 presentations at the symposium Web site, www.gsd.harvard.edu/conferences/watersymp.)
     
Among the presenters at Harvard’s symposium was Bruce Ferguson, FASLA, whom France describes as “the world’s expert on stormwater infiltration, landscape architect or not.” He is professor and associate dean of the School of Environmental Design at the University of Georgia in Athens and past president of the Council of Educators in Landscape Architecture. His publications include Stormwater Infiltration (1994) and Introduction to Stormwater: Concept, Purpose, Design (1998), and he contributed to Tom Richman’s highly acclaimed Start at the Source, a site planning and design manual for stormwater pollution prevention in the San Francisco Bay Area. Ferguson has received awards for projects protecting watersheds in Florida, Georgia, New York, and the metropolitan areas of Pittsburgh, Los Angeles, and San Francisco. He also has interesting things to say about the role of landscape architecture in stormwater work.
     
When most people think of landscape architecture they tend to think of someone who “prettifies” an outdoor space. But aesthetics is only a small part of the story, emphasizes Ferguson. “If I had to choose a single word, it would be integration: bringing different elements together. Think of the relationship between engineering and landscape architecture as a diagram. On the horizontal axis is everything a landscape architect needs to bring to site design.” On that bar lies aesthetics as well as technical and analytical skills, knowledge of the environment, understanding of human needs and functions, negotiating skills, and so on. “Now imagine the vertical axis as engineering. It intersects with the horizontal one only at the point representing technical matters.”
     
While Ferguson stresses the importance of engineering as a critical tool, he points out that site design benefits from the breadth of skills landscape architects bring – their inherently integrative approach, their ability to mediate – to create a synthesis “out of a dialogue of different people with different interests, pushing at the plan from different directions.” Above all, Ferguson stresses, the design work of landscape architects, in addition to being integrative, is site specific and multifunctional. This has important implications for stormwater design.

Porous concrete “lattice” pavers filled with gravel
Porous concrete driveway
Orange County Civic & Convention Center, Orlando, FL

While hydrologic modeling and analysis require technical training beyond the typical undergraduate program in landscape architecture, the concepts behind them are relatively simple. Ferguson has written about hydrology extensively and always underscores the nature of landscapes as open, dynamic systems with inflows and outflows of water resources. In healthy, predevelopment landscapes, precipitation represents the inflow that infiltrates into vegetated soil, providing evapotranspiration to sustain the ecosystem; percolating through the filtering soil to maintain a continual, moderate base flow; providing regular recharge to groundwater supplies; and discharging moderately into surface waterways. Urban development, in contrast, has created the “disease” of runoff. By creating impervious surfaces and denying access of precipitation to the soil, we have created more than the problems of point- and nonpoint-source pollution. Conventional stormwater management, by rushing water downstream, also aggravates flooding; reduces groundwater, base flow, and drinking-water supplies; and encourages erosion, flooding, and habitat destruction.
     
Ferguson sees the only hope of a real cure in restoring infiltration as close to the source of inflow as possible. Numerous techniques are possible, for new development as well as retrofits. Infiltration basins, including vegetated swales, grass basins, constructed wetlands on larger sites (with unlined sides of permeable soil for overflow), and stone-filled trenches can all be remarkably effective in capturing water, including the much more frequent small precipitations that contribute significantly to annual inflow. Various forms of porous materials (porous asphalt, grassy pavers, aggregate-filled pavers, and porous concrete) are another important contribution to healing the disease of imperviousness. But all these applications must be used wisely, with appropriate methods applied to each specific site in ways that maximize their benefits. “No one approach – not even any fixed combination of approaches – is a panacea,” warns Ferguson. This is an aspect of stormwater design where the landscape architect’s instincts serve the project well, since he or she is trained first and always to treat each site as inherently unique. Landscape architects are also trained to get the most out of each designed feature. Multifunctionality saves money. Porous pavement, for instance, when correctly accounted, serves both as a necessary structure and part of the stormwater system, and also cuts down on the need for pipes and gutters.
     
While Ferguson is hopeful that federal regulations will spur more environmentally healthy development, he nonetheless worries about a potential shopping-list approach to stormwater best management practices (BMPs). “The notion that if you choose from a list you must be doing something right makes me very nervous. The concept of BMPs can lead people to believe that if they fly over the watershed and drop their BMPs out of a helicopter they’ll do some good no matter where they land. That’s just not the way it works when it hits the specific site. Aren’t you glad your physician doesn’t work that way, following a cookbook approach?”
     
What, then, is innovation? Ferguson even has reservations about the use of the word. For one thing, he sees tremendous irony in it. “Treatment wetlands, stormwater infiltration, porous pavements, vegetated swales, and bioengineering have all been around for 30 years or longer. They are not innovative if “˜innovative’ means “˜new to the world.’ They are only innovative in the sense that they are unfamiliar to many people, out of line with local convention.” He’s concerned, too, that today’s innovation not become tomorrow’s entrenched bureaucratic standard. “Progress ought not to stop with us.” Ferguson sees the spirit of genuine innovation in those throughout the design professions who take a “scientific approach – and by that I mean you are respectful of facts, especially new facts as they emerge. You need to be both open to new ideas and rigorous in your evaluation at the same time.”

Where Innovation Occurs: Municipal Foresight

The city of Austin, TX, has played a proactive role in stormwater issues since the mid-1970s, making it one of the earliest urban centers to provide comprehensive stormwater regulation at the local level. The population of the area has been growing rapidly since that time, and city officials recognized the potential threat of flooding, erosion, and pollution caused by stormwater, which could harm the Colorado River, local lakes, and the important Edwards Aquifer recharge area that is located below parts of the city. Average annual rainfall is 32 in., but with dry periods between precipitation events. After working with the United States Geological Survey to study several watershed areas, Austin began working with EPA’s Nationwide Urban Runoff Program in 1981 and has been expanding its monitoring efforts ever since. In 1982 a dedicated stormwater utility fee was established to preempt erosion and flooding and to improve water quality; this fee funds the lion’s share of the city’s stormwater management efforts. In 1998 the fee provided $15 million; the 1999 monthly residential charge was set at $4.45 per unit, with commercial and industrial entities paying $48 per developed acre per month.

Lower Colorado River Authority Campus

Austin also has enacted comprehensive stormwater ordinances and, with the city’s aggressive monitoring program, they seem to have teeth. To be a landscape architect involved in site design in Austin means to take stormwater seriously. It has been the trend for several years now for landscape architects, together with engineers, to be first on the scene of any design project, observe Earl Broussard and Brian Ott of TBG Partners Inc., which has offices in Austin, Dallas, and Houston. Broussard, founder of this single-discipline landscape architecture firm, maintains that Austin is well ahead of other cities in the state; hence, the NPDES Phase I and II rules have not caught them napping. For a time, city regulation was more stringent than either state or federal mandates. Ott, who is also a principal in the firm, says, “While heavy regulation makes development in Austin more expensive than in a lot of other regions in the country, the environmental measures that have succeeded politically in the city have made Austin an attractive place to live, still in the midst of a boom.” Broussard believes that Austin’s high median income and education level are also part of the equation. When asked which areas of the country are the places to look for creative solutions to stormwater pollution, he only half-jokingly cites the famous movie line: “Follow the money.”
     
Perhaps TBG Partners’ most impressive showpiece in stormwater design is the Lower Colorado River Authority (LCRA) Campus. LCRA is an agency formed in 1934 to meet water and electricity needs for central Texas. Because its mandate is water conservation and water quality, it wouldn’t do for the design of its headquarters to be anything but a model of what it preaches, even though LCRA was not required to comply with city ordinances. In hiring TBG Partners, LCRA had three requirements: (1) The landscape architect was to be an active participant throughout every phase of development, (2) the project was to demonstrate state-of-the-art xeriscaping to educate the public on its functionality and beauty, and (3) the landscape architect was to create wet and dry ponds, implementing vegetation with the multiple functions of pollutant uptake, a basis for future research, and aesthetic appeal.
     
The 17-ac., moderately sloping (10%) site on the banks of Lake Austin (as the Colorado River is called within downtown limits) has soils of alluvial sand and silt, with smaller proportions of limestone bedrock and clay. Large stands of live oaks were preserved for their beauty and their multiple ecological benefits. A major site constraint was the enforcement of large setbacks because of neighborhood boundaries; major portions of development were pushed to the front of the property, which was also the low point and the location of the major water-quality features. On the main-campus section a filtration pond collects runoff from the western side, which then feeds via underground perforated pipe into the large lawn area below. Nearby is a detention pond that collects runoff from all parking and other impervious cover on the main campus. A wet pond across the street then intercepts water from the detention pond and cleanses it with the help of aquatic plantings before it is dispersed into Lake Austin. An LCRA botanist worked on the team to select the pond plant species best suited for pollutant uptake. These plants must be harvested seasonally to reduce pollutant load; the harvesting in turn allows for the introduction of new species and research on comparative effectiveness. Fifty-four different plant species were used to illustrate xeriscaping principles. A memorial wall, lined along its length by a narrow pool and fed by evenly spaced spouts and a waterfall at its head, graces the walkway leading to the main building. It serves as a metaphor for the Colorado River and commemorates supporters of LCRA’s success. The LCRA Campus has won the City of Austin Xeriscape Award for the large project category and an ASLA Merit Award. Ott says the project, with all of its amenities, cost only slightly more than conventional, hard-engineered stormwater design. That small premium is compensated for, he says, by the fact that “the LCRA project has paved the way for more sensitive development in and around the central Texas area.”

Where Innovation Occurs: When Threat Looms

In the greater metropolitan Atlanta area, stormwater has caused headaches for state and local government officials. In addition to a combined sewer overflow problem and point-source pollution from wastewater treatment facilities, Atlanta is coping with a 1996 federal ruling that has charged both EPA and the State of Georgia with setting total maximum daily loads for pollutants in the state’s waterways by 2004. In a related issue, turbidity standards for the state’s waterways created when the Georgia Erosion and Sedimentation Act was amended in 1989 were called into question when it became clear that the building and construction industries had trouble meeting the new standards. In 1993 the State Legislature asked the Georgia Board of Regents to put together a scientific committee (dubbed “Dirt I”) to review the issue and recommend appropriate levels. The panel suggested that land-disturbing activities should not cause instream turbidity to increase by more than 25 nephelometric turbidity units (NTUs). It soon became clear, however, that commonly used construction practices often made achievement of the 25-NTU limit unattainable at some sites.
 

Oregon Museum of Science & Industry in Portland

A state senate committee called for a second panel to analyze standard construction practices to see how they could be modified to reduce erosion and sedimentation. This second scientific committee, formally called the Erosion and Sedimentation Control Technical Study Committee, is logically nicknamed “Dirt II.” Active on the Dirt II Committee is Michael Breedlove, mentioned above. As part of Dirt II’s mission, Breedlove Land Planning is engaged in a research demonstration project associated with construction of the Big Creek Elementary School in north Fulton County. Tom Sill, planning director of the Chattahoochie/Flint Regional Development Center, applied for and received a grant from Georgia’s Environmental Protection Division to conduct the scientific study, with Richard Warner, director of the Surface Mining Institute, hired as research consultant. Breedlove’s firm has been hired by the architectural firm of Collins, Cooper & Carusi to assist in the design of construction site erosion and sedimentation control features, some of which will become part of the permanent onsite stormwater management system. He works hand in glove with Warner, who is the creator of SEDCAD 4, a computer modeling software package for erosion and sedimentation control analysis. The goal of the Big Creek demonstration site is to monitor the effectiveness of new erosion control measures and ultimately provide cost-benefit analysis.
     
What is intriguing about the project is its design philosophy, which uses standard and economical erosion control practices with only minor, but important, adaptations. By means of a strict staging sequence of sediment controls, whereby the perimeter is completely secured first, construction can proceed on a relatively large disturbed site footprint while keeping the potential for offsite impact very low, thus reducing construction costs. A logical treatment train at Big Creek involves the use of a seep-berm riparian zone system. The seep berm retains smaller storms, with further treatment from a passive sand filter. Water seeping from the berm meets the filter fence, which spreads the water and releases it slowly to the forested riparian zone. The effluent is predicted to produce virtually zero NTUs, since all discharge should infiltrate within the first 100 ft. of riparian zone. An active dewatering system is also being employed, using the standard concept of a stormwater sediment control basin retrofitted with a multichamber component. Its performance is enhanced by a fixed siphon with a rock underdrain for primary treatment, with a floating siphon to discharge higher-elevation effluent from the second chamber into a slow sand filter. Filtered water emerging from the second chamber proceeds to a riparian zone for further treatment before reaching the floodplain. The technology employed is inexpensive, and it is hoped that the extensive monitoring system installed for Dirt II will prove that simple but stringently adhered-to techniques will reduce peak flow to well below predevelopment levels, increase soil moisture and evapotranspiration, and help recharge groundwater by dispersing water to adjacent riparian areas.
     
Breedlove is adamant about the precise staging and sequencing of construction activities. Although, as he says, “It’s just good old-fashioned common sense,” he finds that contractors undergo a “paradigm shift” when first employing the techniques he espouses. “We need to close down the site on a daily basis, even if it’s 500 square feet a day. We’re going to get it green, and we’ll keep closing it down until the only area disturbed is right around the building footprint. We’ve got to get the focus on the sitework and away from that building until everything’s under control; otherwise we lose the battle. And we just can’t afford to keep losing battles.”

Where Innovation Occurs: People With a Mission

The City of Portland, OR, has a reputation for encouraging innovative stormwater management. One of the people behind that reputation is Tom Liptan, ASLA, environmental specialist in Portland’s Bureau of Environmental Services (BES). He came to the job in late 1989, just as Portland began gearing up to respond to NPDES Phase I permitting regulations. In that c

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