O'Fallon, MO Environmental Rules: Erosion Control (2026)

), the Federal Water Control Act, and the Missouri Department of Natural Resources' State Operating Permit MO-R100A (or MO-R109 in a valuable water resource area). All erosion and sediment control measures must be fully installed before any major land-disturbing work begins, so mud, silt, dirt and debris do not run onto streets, sidewalks, rights-of-way or adjacent property, or silt up storm drainage systems on- or off-site. Runoff into receiving streams from land disturbance areas greater than three acres cannot exceed the two-year, twenty-four-hour peak runoff rate for that area's pre-developed state, and temporary discharges cannot accelerate erosion of a receiving stream's channel.

Controls and temporary facilities must be designed, at a minimum, to accommodate stormwater flows from a fifteen-year, twenty-minute design storm, using the Rational Method and the runoff coefficients set out in the code's Table 1 for the specific ground cover involved. If controls installed under an approved plan fail to meet these performance standards, the Director of Engineering or a designee may require the permittee to submit modified plans. SWPPPs must otherwise follow the Missouri Department of Natural Resources' Protecting Water Quality Field Guide, latest edition, for design criteria such as sediment trap, sediment basin and silt fence sizing and structural life limits.