In an effort to improve water quality in the Tar-Pamlico River Basin and to reduce flooding, the City of Rocky Mount has implemented certain design requirements for new development and redevelopment sites. These requirements are broken down into water quality and water quantity standards.
The City's water quality standards were adopted as a result of the Tar-Pamlico Nutrient Sensitive Waters Rule. This rule states in general that that total post development offsite nutrient loading must be 30% lower than the pre development loading. For new development, this translates into a total offsite loading of four pounds per acre per year of Nitrogen, and four tenths of a pound per acre per year of Phosphorous. These nutrient reductions are achieved through the use of Best Management Practices (BMP's) such as wet ponds,engineered stormwater wetlands, bioretention cells, or restored diffuse flow through riparian buffers.
Water quantity standards were implemented in an effort to reduce nuisance flooding problems within the City and its Extraterritorial Jurisdiction. The City requires that pre development run off rates be maintained after development for the 1-, 10-, and 25-year 24-hour storms. Again, this runoff control is achieved through the use of detention devices or BMPs.
The City has developed a Stormwater Design Manual which outlines the design requirements for new development and provides guidance on the calculations and data required for approval.