by George R. Frantz, AICP, ASLA
Stormwater management approaches in the US are evolving dramatically. For most of the past three decades, the standard approach was to store water and control its rate of runoff into the environment. In the past decade, the treatment of stormwater for urban runoff pollutants has gained traction as the impact of such pollutants has become apparent. Throughout the country, developing green infrastructure to treat stormwater pollution is moving from the fringe of the practice to mainstream acceptance.
New York strongly encourages the adoption of green infrastructure approaches to stormwater management to reduce urban runoff pollutants. The New York State Stormwater Management Design Manual released in 2015 sets as design objectives (1) the capture and treatment the full water quality volume of runoff; ( 2) the capacity to remove 80 percent of total suspended solids (TSS) and 40 percent of total phosphorous (TP); (3) mechanisms for the pre-treatment of stormwater; and (4) an acceptable operational lifespan for stormwater systems.
One issue that New York and other states and municipalities fail to address, however, are regulations that dictate a hodge-podge of small, privately owned and maintained (or not) stormwater management systems. General regulatory practice is that stormwater must be managed and treated on the parcel that generates it. This has resulted in a landscape of single-function detention or retention “craters” in developed areas, with little aesthetic appeal or function beyond stormwater management.
In recent years, cities in China have begun to grapple with the issue of stormwater management and treatment. Chinese planners and designers are faced with three daunting challenges: accommodating unprecedented urbanization, the need to carefully husband land resources, and the need to retrofit older urban areas with stormwater management and treatment systems.
Their response has been the wetland park concept. The wetland park addresses the multiple objectives of managing and treating stormwater, providing for critically needed public park and open space resources, and remediating groundwater and riverine pollution. In Shanghai the pioneering Houtan Park by Turenscape restored 33 acres of the Huang Pu river waterfront for public recreation, remediated a former industrial site, and serves as a stormwater management and treatment facility for the 2 sq. mile Expo 2010 site. During non-rain periods, while thousands of Shanghai residents enjoy the 1.3 miles of waterfront recreation, polluted water from the Huang Pu is diverted into the park’s wetlands for treatment and discharged back into the environment.
Since completion of Houtan Park two other facilities have been built in the Shanghai metropolitan area and others are on the boards as the city advances the new Sponge City concept, and aggressive development of new public parks. Other cities in China, such as Tianjin, Jinhua in Zhejiang province, and Harbin in Heilongjiang province, have developed wetland parks
The wetland park concept has great potential to address stormwater management challenges, the provision of public park and open space, and ecological restoration in the USA as well, particularly in older urban and suburban areas built up before the advent of stormwater management practices, and which often lack adequate public park and open space.
The Town of Geneva, NY, is addressing the challenge of revitalizing and re-purposing a 400-acre declining 1960s suburban commercial area in its new comprehensive plan through the creation of a new mixed-use town center. The lack of stormwater management facilities in the area has caused flooding problems downstream along Castle Creek in the adjacent city of Geneva for decades. The town saw an opportunity to use local topography and hydrology downstream of the area to implement a district approach to stormwater management.
The new plan proposes to eliminate the multiple privately owned and maintained systems that are the norm with a single large, publicly owned and financed facility. Two low-lying areas totaling about 18 acres that are unsuited for development and that also include small wetland complexes and a riparian corridor, would be developed as stormwater management facilities and wetland preserves. These preserves would be naturalistic landscapes that would include constructed wetland areas to manage and treat stormwater.
The preserve would include public trails and overlooks, and places for passive informal recreational activities, for several thousand existing and future residents of the area, while also expanding habitat for wildlife. The preserves would also be nodes on a proposed 6.5-mile bikeway that would knit together several town and city neighborhoods and parks, and open access to a wider population.
Recently, a development plan for the Inlet Valley area in the Town of Ithaca south of Ithaca, NY, proposed a district approach to stormwater management that would also integrate wetland treatment systems and new public park space (Inlet Valley Ithaca Plan: Economic Development Feasibility Study and Strategic Plan). This facility would also enable the management and treatment of stormwater from existing development in the area without costly retrofits or proliferation of privately owned and maintained systems.
The main challenge to implementation of the wetland park concept, however, remains a policy and regulatory challenge. Stormwater management has historically been the responsibility of developers, not local or regional government. State regulations reflect this. We need to re-think the regulations in many states in order to make more efficient use of land and funding as we strive to protect our critical water resources. By integrating park and preserve functions into the equation, we can both provide recreational opportunities, and help the general public gain an appreciation of our wetland environments as something more than wasted land.
George R. Frantz, AICP, ASLA, Associate Professor of the Practice, Department of City & Regional Planning, Cornell University
George Frantz has taught planning field workshop classes in communities ranging from the Ninth Ward of New Orleans to Catskill Mountain resort towns. He has an active private practice in land-use planning and design. His primary areas of expertise are in urban design and comprehensive land-use planning and zoning, with particular emphasis on addressing the needs of agriculture and the protection of environmentally sensitive lands. His current research interests include Chinese and American cities and their potential to evolve into more environmentally and socially sustainable communities.