The following is the second installment of the two-part series excerpted from the Trust for Public Land’s (TPL) Center for City Park Excellence (CCPE) publication, City Parks, Clean Water: Making Great Places Using Green Infrastructure. To view Part I, click here.

Part II

Different Solutions and How They Actually Work

There is no simple formula for green infrastructure in parks. For one thing, geography alone dictates that there are dozens of different kinds of urban parks, from narrow stream side greenways to large flat forestland, from stepped brick plazas to lush community gardens, and from windswept hilltop viewpoints to massive sports complexes. But when it comes to water-smart parks, there are three principal issues:

• Is the physical relationship of the park to the surrounding community such that a redesign could reduce neighborhood flooding or the pollution of downstream waterways?
• Does the park have any available space for water flow and storage?
• Is the composition of the existing soils, water table, and underlying rock such that the park can absorb a significant amount of water in the necessary amount of time?

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Many of you may know The Trust for Public Land (TPL) as an organization devoted to the protection and support of the places people care about and the creation of “close-to-home parks” — particularly in and near cities, where 80 percent of Americans live. Through its Center for City Park Excellence (CCPE), TPL also explores the many issues that affect the success of urban areas’ park systems. CCPE’s most recent publication, City Parks, Clean Water: Making Great Places Using Green Infrastructure, looks at the many ways that parks can help with the control of urban stormwater.

Using case studies, data tables, and interviews with national experts, the report explores both new and existing parks, including in-depth studies of water-smart parks in Atlanta, Birmingham, Alabama, Cambridge, Massachusetts, New York, and Shoreline, Washington. The following is the first installment of a two-part series excerpted from the report.

Lisa Nabor Cowan, ASLA, Sustainable Design & Development PPN Officer, Principal, Studioverde

Part I: City Parks, Clean Water, Green Infrastructure

The effort to clean our nation’s waterways has been underway, with increasing strength, for more than 50 years. Great progress has been made, particularly against pollution from untreated sewage and unregulated factories. Rivers no longer catch on fire, oil slicks are a rarity, and most raw discharge pipes have been eliminated. But in cities there remains work to be done, with most urban waterways still not clean, not swimmable, not safe for fishing, and sometimes not even pleasantly boatable.

The primary culprit, as all landscape architects know, is pollution from runoff from paved surfaces – streets, sidewalks, driveways, parking lots, roofs, patios, plazas, even playgrounds that quickly shed the rain. The solution is to hold back the water where it hits, slow it down so that the destructiveness of erosion and contaminants are controlled, and clean it before it reaches a waterway.

With two different methods of doing this – using giant holding tanks for storage or a natural, spongier approach for infiltration – the U.S. is at a critical decision point in how it will allocate billions of dollars in the coming decades.

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