Dr. Ada Wossink
CALS
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Two Neuse Education Team members have published a report that examines the most economical approaches to dealing with the environmental and economic damages wrought by stormwater runoff.
The document, The Economics of Structural Stormwater BMPs in North Carolina, (at: http://www2.ncsu.edu/unity/lockers/users/g/gawossin/Structural_Stormwater_BMPs.pdf ) should serve as a useful guide to engineers and municipal, county and state officials trying to cope with environmental damage done when impervious or disturbed areas are created by urban construction and resultant inadequate stormwater management. The study was performed thanks to a grant from the UNC Water Resources Research Institutes' Stormwater Consortium.
Dr. Ada Wossink
CALS
photo
Pavement pouring, building construction and land clearing increase stormwater runoff's volume and speed and can affect the environment adversely through changes in volume, timing and location of the stormwater discharges and the movement of pollutants from the site to water bodies.
"These activities contribute to flooding, and to property and habitat damage, or stormwater quantity impacts," says report co-author Dr. Ada Wossink, Neuse Education Team (NET) member and an associate professor and extension specialist in NC State's College of Agriculture and Life Sciences' Department of Agricultural and Resource Economics. "They also lower water quality through stormwater quality impacts by increasing the flow of human pollutants such as oil, fertilizers and pesticides, and of natural elements such as nitrogen, phosphorus and sediment into the water."
"Degradation of lakes, streams and wetlands due to urban stormwater reduces property values, raises our public water utility bills and reduces tourism and related business income," says co-author and NET member Dr. Bill Hunt, an assistant professor and extension specialist in the College of Agriculture and Life Sciences' Biological and Agricultural Engineering Department.
To combat these problems, innovative stormwater best management practices (BMPs) are becoming more common nationwide, Hunt notes. These innovations run along the continuum of small, or site-specific, to large, or regional-scale practices.
A major question facing design engineers and developers is how to select the optimum practice, keyed to a particular watershed size, land cost and the targeted pollutants.
The Economics of Structural Stormwater BMPs in North Carolina focuses on which BMPs work best and their relative costs, including both installment (construction and land) and annual operating costs (inspection and maintenance).
"Our goal," says Hunt, "is to present decision-makers with an economic tool to determine the best BMP to choose for North Carolina conditions, given a particular watershed's size and its type, as described by curve number (CN) range, soil type, and pollutant type."
The research report includes the results of systematic applications of the economic decision-making tool to various N.C. conditions to assess which BMP is preferable from an economic perspective in each situation, she says
The authors drew the following conclusions on structural stormwater BMPS in North Carolina, based on their analysis:
Costs-per-acre-treated
Removal efficiency
Costs per percent pollutant removed
Based on nitrate the conclusion is more mixed. Where the opportunity cost of land is very high (commercial use), a wet pond is preferable over a bio-retention area for small watersheds (10 acres or less).
Management
