Post-construction stormwater BMP documentation in South Carolina

Post-construction stormwater BMPs are the permanent stormwater management structures that remain on a development site after construction ends and the NPDES construction permit is closed out. These are different from the temporary erosion and sediment controls installed during grading. A wet detention pond, a bioretention cell, a constructed wetland, or a series of vegetated swales are post-construction BMPs. They manage stormwater runoff from the developed site permanently, and they require ongoing inspection and maintenance to function as designed.

In South Carolina, post-construction stormwater management requirements vary depending on jurisdiction. SCDHEC administers post-construction stormwater standards for sites that disturb two acres or more that discharge to impaired waters or to waters with a TMDL. Many municipalities and county governments have adopted local stormwater ordinances that extend post-construction requirements to smaller sites or impose more frequent inspection schedules. Property owners, HOAs, and facilities managers responsible for these structures are often surprised to learn that the inspection obligation continues long after the contractor leaves.

A post-construction BMP inspection is an assessment of the structure's physical condition and operational performance. For a detention pond, this means checking the outlet structure (weir elevation, orifice condition, emergency spillway), the embankment and side slopes for erosion or animal burrows, sediment accumulation in the forebay and main pool, and the condition of any vegetated buffer around the pond perimeter. For a bioretention cell, it means checking for ponding beyond the design drawdown time, inlet and outlet condition, soil media permeability, and plant establishment.

The inspection record needs to document findings at each component of the structure, note any deficiencies observed, and specify what corrective action is required and by when. For structures subject to recorded maintenance agreements, this record is also the evidence that the maintenance obligation is being met.

Drone aerial inspection is well suited to post-construction BMP documentation for several reasons. Detention pond embankments, emergency spillways, and inlet/outlet channels are often partially or fully inaccessible on foot without wading. A drone covers the full surface area of a pond, both slopes of an embankment, and the downstream channel condition in a single flight. For larger regional stormwater facilities or sites with multiple BMPs spread across the property, aerial coverage produces a complete, dated photo record of every structure in less time than a ground walk.

Deliverables for post-construction inspections include GPS-tagged photos organized by structure and component, a written condition summary for each BMP, and a flight record with date, time, and weather conditions. This format matches the documentation requirements under most local stormwater maintenance agreements and supports the annual inspection reports that many jurisdictions require.

Commercial property managers, HOAs with stormwater obligations, and facilities teams managing institutional campuses often have multiple post-construction BMPs across their properties or across a portfolio. Aerial documentation on a scheduled annual or semi-annual basis builds a consistent photo record of each structure over time, documents deterioration patterns before they become failures, and provides the inspection records required under maintenance agreements.

SC Drone Services covers post-construction stormwater BMP inspections statewide. For construction-phase NPDES BMP documentation on active permitted sites, see our BMP inspections service page. Upstate SC sites are handled by our Upstate partner, Upstate Drone Services.