Post Construction

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Regular maintenance is crucial to ensure that a water quality device effectively removes stormwater pollutants. Pursuant to Section 7 of the Guilford County Development Ordinance, engineered stormwater control structures must be inspected annually and the County is required to record the results and notify the responsible property owner or owner’s association when maintenance or repairs are necessary. Upon inspection, if repairs are needed, the responsible party is given 90 days to make the necessary improvements. The Guilford County BMP Design Manual and the Stormwater Watershed Protection/Stormwater Management Manual provides general design guidelines for major BMPs and recommended maintenance schedules.

The Guilford County Planning & Development Department revised the Development Ordinance to comply with the post-construction site runoff control requirements of NPDES Phase II stormwater regulations. Guilford County continues to implement the following post-construction stormwater management practices and strategies:

  • Watershed development plan review;
  • Require alternate and engineered stormwater controls for development and redevelopment as defined in Section 7 of the Guilford County Development Ordinance;
  • Require and enforce stream buffers;
  • Conduct structural stormwater BMP inspections;
  • Implement and enforce Section 7 of the Guilford County Development Ordinance.


Communities across the State of North Carolina must manage rainfall that runs off roads, streets and parking lots. This runoff is called “stormwater.” To manage stormwater, many treatment devices, called Best Management Practices (BMPs), are required to be built based upon site requirements for protection of the overall water quality within watersheds. Generally BMPs focus on water quality problems caused by increased impervious surfaces from land development.

BMPs are control measures taken to mitigate changes to both quantity and quality of urban runoff caused through changes to land use. There are a variety of BMPs available; selection typically depends on site characteristics and pollutant removal objectives. These devices include: wet retention ponds, bio-retention areas, swales, stormwater wetlands, permeable pavement, rainwater harvesting systems, proprietary devices, and level spreaders. Examples of existing BMP devices within Guilford County can be shown below.

BMPs are designed to reduce stormwater volume, peak flows, and/or nonpoint source pollution through evapotranspiration, infiltration, detention, and filtration or biological and chemical actions. BMPs also can improve receiving-water quality by extending the duration of outflows in comparison to inflow duration (known as hydrograph extension), which dilutes the stormwater discharged into a larger volume of upstream flow.


BMPs must have annual, and sometimes more frequent inspection and maintenance to perform as intended. Maintenance includes hydrologic and water quality function, landscape functions, and consideration of impacts on human health and safety. Currently the County is tasked with inspecting 300 +/- water quality devices throughout the un-incorporated areas and contracted townships with new projects coming under annual inspections within the next year. Maintaining the water quality devices in accordance with the operation and maintenance guidelines on an approved site plan is the sole responsibility of the property owner. Guilford County’s Development Ordinance and the appropriate North Carolina Administrative Code requires the inspection of the permanent water quality devices annually to ensure they function efficiently as designed and intended. Annual inspection reports are forwarded to property owners and/or associations for maintenance requirements. Any deficiencies noted in the future inspection reports must be addressed within 90 days of the date of the letter sent.


The Watershed Protection/Stormwater Mangement Section is responsible for the annual inspection of all structural water quality control devices located within the unicorporated limits of Guilford County. Staff maintains an inventory and inspection schedule for the stormwater control devices. Examples of typical deficiencies found during the BMP inspections include overgrown vegetation, trees on dam embankment, lack of sufficient ground cover, erosion, and non-functioning BMPs. The Watershed Protection/Stormwater Mangement Section works with the responsible parties to ensure that the required maintenance is performed. The non-compliant water quality devices are brought before the Board of Commissioners for enforcement on an as needed basis.


As a new innovative approach to ensure meeting and maintaing compliance with stormwater BMP devices and reducing the time needed for researching associated documents and past records, the Watershed Protection/Stormwater Management Section of the Planning and Development Department in coordination with the Geographic Information Systems Department of Guilford County has worked to develop a superior product for the general public (HOAs, business/property owners, maintenance contractors), design engineers, and staff that makes available a 24 hour service through the GIS: Public Data Viewer. The one-stop, user-friendly “virtual” platform location allows users to view associated documents along with current and past inspection reports, pictures, and site plans of each individual BMP device to enhance the efficiency and effectiveness of quality customer service. The GIS template provides citizens with immediate access to an extensive catalog of resources and serves as a platform where they can further share information and best practices while understanding the existing conditions of each BMP device.As a goal of improving service delivery and eliminating the need for maintaining a large volume of hardcopy files, staff has developed this web based GIS application to deliver through a digital platform. This will greatly enhance the ability to have information readily available anytime to not only view but download documents without the need for waiting on staff to relay information over an extended amount of time. From this, the general public is able to view past maintenance requirements to find any trends that may continue to occur and understand the needs of completing these requirements by viewing the associated documents for each individual BMP device.

The development of this GIS based platform was to provide the groundwork for electronic document management and reference for the Watershed Protection/Stormwater Management Section. In turn, as a greater number of documents are received electronically, the section can continue with indexing BMPs to ensure rapid retrieval and having a digital association between the associated documents and their physical location within GIS. From this, the platform is useful as an overall repository for digital files, and to ease the on sight of losing hard copy files. From this, this project has greatly assisted with the overall documentation and record retention for each BMP device that the County is tasked with inspecting, while maintaining an organized and efficient process for inspections. Further, staff within the Watershed Protection/Stormwater Management Section is working towards using handheld tablet devices for field inspections and further supporting onsite meetings with property owners, associations, contractors, design engineers, etc. in support of the GIS based platform.