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The US 70 Clayton Bypass in Wake County was considered a top priority project by the North Carolina Department of Transportation (NCDOT). This new location facility will relieve traffic congestion along a major arterial route entering Raleigh from the east. However, a number of environmental issues had to be overcome before construction could commence.
The N.C. Division of Water Quality (NCDWQ) and the U.S. Fish and Wildlife Service requested a detailed study of the new road alignment and its potential impacts on water quality. Preventing water quality degradation was particularly important to development of this project due to the presence of federally protected mussel populations in area waterways, including the nutrient sensitive Swift Creek system.
EcoScience Corporation was asked to determine impacts on water quality by evaluating pre- and post-project pollutant loadings in the 92-square mile watershed area. Comparative modeling of present and future loading for total nitrogen, total phosphorus and sediment (both overland and in-stream) was conducted using advanced modeling techniques enabling the prediction of pollutant loads at both large and small evaluation scales. Study area boundaries were defined through stakeholder coordination involving the modeling team, land use consultants, NCDOT, and NCDWQ. Land use data in digital format were integrated into the water quality models using ARCVIEW software.
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