BMP inspection frequency requirements for construction sites in South Carolina

South Carolina construction sites with NPDES permit coverage must inspect stormwater best management practices on a regular schedule. The requirement comes from the SCDHEC Construction General Permit (CGP), which applies to any land-disturbing activity that will disturb one acre or more of ground surface.

What the permit requires

The CGP sets two inspection triggers. First, inspections must occur at least once every seven calendar days throughout active land disturbance. Second, an inspection is required within 24 hours following a rainfall event of 0.5 inches or greater. These two requirements operate independently: a rain event inspection doesn't reset the seven-day clock.

Inspections are required from the start of land disturbance through final stabilization. Final stabilization means the entire disturbed area has achieved at least 70% permanent vegetative cover, or has been covered with hard surface such as pavement or concrete. Until that threshold is met, the inspection schedule stays active even if grading is complete and framing has started.

What gets documented

Each inspection needs to cover every BMP on the site: silt fence, sediment basins and traps, inlet protection devices, construction entrance stabilization, slope protection, and any area where erosion is active or a BMP has failed. The inspection record needs to include the date, weather conditions, findings at each BMP location, and any corrective action taken or needed. That record goes into the SWPPP and stays on file for at least three years.

SCDHEC inspectors check that the inspection records match the actual site conditions and are being conducted on schedule. A site without dated inspection records is in violation regardless of whether the BMPs are physically in good condition.

Where drone inspections fit

A drone inspection covers a construction site faster and more completely than a ground inspection on a large or difficult site. A 40-acre site with multiple sediment basins, several hundred feet of silt fence, and active grading on multiple fronts takes 30-45 minutes by drone versus two or more hours on foot. The drone produces GPS-tagged photos organized by BMP type and location, the same format required for the SWPPP inspection log, delivered within 48 hours.

For sites running weekly inspections, a drone flight every seven days builds a dated aerial record automatically. That record is useful beyond NPDES compliance: it documents site conditions at each stage of construction, which matters if a BMP fails and causes a downstream sediment event, or if a property owner disputes site conditions after the fact.

Rain event inspections

The 24-hour rain event requirement is where most NPDES violations happen. A 0.5-inch event after hours means the inspection has to be done the next morning before crews start. A drone can cover the site at first light in the same time it takes a superintendent to do a partial ground inspection. For sites in Greenville, Spartanburg, Anderson, and Pickens counties, we can schedule same-day or next-morning flights for rain event inspections.

FAA Part 107 certified. Insured. Based in Clemson, SC, serving construction sites throughout Upstate SC.