Landscape Architecture Resource

by Leda Marritz

Urban and suburban places all over the world are experiencing unnecessary flooding and pollution because their heavily-compacted urban soils simply can't manage the rate, quality and volume of storm water as effectively as needed.

Nearly all of the associated problems [of water quality and habitat degradation in urban streams] result from one underlying cause : loss of the water-retaining and evapo-transpirating functions of the soil and vegetation in the urban landscape.

This comes from an upcoming publication that the EPA recently commissioned from the National Research Council to provide suggestions for improvement on stormwater-related issues, Urban Stormwater Management in the United States. The report goes on to say:

Stormwater Control Measures that harvest, infiltrate, and evapo-transpirate stormwater are critical to reducing the volume and pollutant loading of small storms.
[Urban Stormwater Management in the United States (A Report by the National Research Council: National Academies Press, 2008) 8.]

The Sustainable Sites Initiative has just released its Guidelines and Performance Benchmarks Draft 2008. The chapter entitled "The Cost of Unsustainable Practices" states:

The undervaluing of soils is one of the singular failings of the conventional development approach.

Cities as diverse as Alexandria, VA (starting on Slide 16), Charlotte, North Carolina and Toronto, ON (page 24) are implementing minimum soil volume requirements and higher standards for planting street trees. This will allow urban trees to live out their natural lifespan and help solve many tree- and stormwater-related development issues. We are on our way, but we aren’t there yet.

Soil is a critical component of sustainable development, providing the basis for healthy plant growth, treating stormwater runoff as a resource, and restoring ecosystem services. By and large we don't give much thought to the earth we walk on, but soils can vary widely in their quality and composition. Healthy soil is critical to our well-being and the well-being of virtually all life. Current research points to an inescapable conclusion: soil volume and quality matters, and we do not have enough of either.

Healthy trees and soil are the most sustainable and ecological stormwater control measures available. By using soil to combine on-site stormwater management with expanded rooting volumes for large healthy trees, we can create an unparalleled ability to restore soil and ecosystem services to developed sites.

Leda Marritz is a marketing manager at Deep Root Partners, LP, an urban landscape products and ecosystem services supplier.