Post-Construction Stormwater Control Measures
Stormwater Control Measures (SCMs) treat stormwater from developed areas. These are referred to as “Post-Construction” because, unlike Erosion and Sediment Controls, SCMs stay in place after construction is completed to improve water quality long-term. SCMs used to be called Structural Best Management Practices (BMPs), a name that is still sometimes used.
Why are Stormwater Control Measures Used?
SCMs are installed based on requirements from our NPDES permit, the Jordan Lake Rules, the Town of Chapel Hill, and other local governments. These requirements are related to:
- Water Quality – The SCMs improve the water quality over a wide range of parameters, with sediment being a primary target. UNC-Chapel Hill’s SCMs also target removal of nitrogen and phosphorus because the University is located upstream of Jordan Lake, which has too many nutrients entering the lake. SCMs can also improve water quality in terms of bacteria, trash, and oils, though those aren’t the specific targets at UNC-Chapel Hill.
- Volume – By controlling the volume of runoff, pre-development hydrology can be matched and impacts to the stream structure and aquatic life can be prevented.
- Peak Discharge – Peak discharge requirements aim to prevent flooding during rainstorms of multiple sizes.
For details on these regulations at UNC-Chapel Hill, see the Stormwater Design Requirements.
Types of Stormwater Control Measures
UNC-Chapel Hill has the following types of SCMs currently installed on campus:
- Rainwater Harvesting (Cisterns)
- Green Roofs
- Permeable Pavement
- Sand Filters
- Wet Ponds
- Dry Detention Ponds
- Vegetated Swales
- Level Spreaders
- Infiltration Beds
- Underground Detention
- Hydrodynamic Separators
- Catch Basin Inserts
- Propriety Devices
UNC-Chapel Hill has installed over 200 SCMs. Some have followed long-established techniques while other have tried new techniques. In particular, UNC-Chapel Hill has led North Carolina on the installation of green roofs, permeable pavement and rainwater harvesting systems. The University has helped create statewide design guidelines for these practices.
Examples of SCMs installed can be found on the projects page.
UNC-Chapel Hill owns and maintains all the SCMs on campus.