Model determines stormwater pollution from building sites

’The model is designed to evaluate the amount of nitrogen and phosphorus found in stormwater runoff from developments − particularly runoff from a completed project, not a site that is under construction,’ said Dr Bill Hunt, an associate professor and extension specialist of biological and agricultural engineering at North Carolina State, who helped develop the model.

’To comply with regional water-quality regulations, cities and counties have to account for nutrient loads,’ Hunt said, ’but the existing tools are antiquated and aren’t giving us sufficiently accurate data.’

The researchers developed the model using chemical, physical and land-use data specific to North Carolina and surrounding states. This allowed them to account for regional conditions, which will improve the model’s accuracy.

US state and local government officials, as well as developers, can plug proposed development plans into the model and get an accurate estimate of the level of nutrients that would likely be included in stormwater runoff from a completed development site. This would give officials key data that they can use to determine whether a proposed development project should be allowed to move forward or require additional stormwater treatment.

’Because the model uses regional data, it could be modified easily for use east of the Blue Ridge Mountains in North Carolina and adjoining states,’ Hunt said.

The model could also serve as a blueprint for similar efforts across the US. ’The primary obstacle to applying this model outside North Carolina − in Florida or Colorado, for example − would be collecting relevant data from those areas and incorporating it into the model’s framework,’ Hunt said. ’The actual model itself would be fairly easy to modify.’

The model was designed in response to state regulations limiting the amount of nutrients that can flow into Jordan Lake in central North Carolina. The regulations affect a host of North Carolina municipalities, including Durham, Greensboro, Chapel Hill, Cary and Chatham County.

In addition to its long-term applications elsewhere, the model will likely be used to help implement forthcoming stormwater-treatment requirements for North Carolina’s Falls Lake Watershed.