A Stormwater Management Plan (SWMP) is required for all subdivision and site plan applications, and certain conditionally-permitted uses, and shall be consistent with the Stormwater Management Regulations described in Chapter 8:3.6 of the Johnson County Unified Development Ordinance.
Who needs to submit a SWMP?
Site Plans and Subdivision Applications:
An electronic version and one hard copy must be submitted for review and approval, at time of initial development application.
Conditional Use Permits:
An electronic version and one hard copy must be submitted for review and approval. The timing of submittal for Conditional Use Permits is dependent upon the supplemental conditions outlined in Chapter 8:1.23 of the Johnson County Unified Development Ordinance.
- A stormwater drainage report to include:
- Project narrative describing how stormwater will be addressed.
- Stormwater calculations, including break-down of pre- and post-developed land use, drainage areas, curve numbers or runoff coefficients, time of concentration, runoff rates, volumes, velocities and water surface elevations.
- Stormwater BMP maintenance and repair plan.
- Design checklist for any proposed infiltration practices (e.g. bioretention cell).
- A signature block that includes signature lines for the property owner and the PDS Administrator.
- Seeding/final stabilization plan.
- Standard drawings and cross sections, with elevations.
- Site plain showing locations of stormwater practices, limits of disturbance, overlay of any sensitive areas, and existing and proposed contours.
Questions? Contact Planning, Development, and Sustainability at 319-356-6083.