Sumner County, TN Environmental Rules: Stormwater Management (2026)

Section 803 of Chapter 8 of the Sumner County Zoning Resolution sets the criteria for requiring a Stormwater Management Facility on Major Subdivisions of three or more lots or a Site Plan. Under Section 803(A), the County requires a detention or water quality treatment facility if any one of four triggers is met: a post-construction discharge increase of one cubic foot per second or more at an outfall during the 100-year storm; a demonstrated inadequacy in a downstream drainage structure; a discharge into a stream the Tennessee Department of Environment and Conservation has rated as having unavailable parameters; or a post-construction flow pattern causing ponding, damage or erosion on downstream properties.

Section 803(B) flips the presumption: detention is assumed required for every Major Subdivision and Site Plan, and the applicant's engineer, not the County, bears the burden of certifying in writing on a County-issued form that the criteria are not met; a missing certification gets the Construction Plans rejected and pulled from that month's Planning Commission agenda. Section 803(C) lets an applicant appeal a disagreement with the County Engineer in writing to the Planning and Engineering Director, who has ten business days to forward it to a private engineering firm of the County's choosing whose determination is final and whose review costs, per Section 803(D), fall entirely on the applicant, with outstanding invoices due before the item can go on the Planning Commission agenda.

Section 803(E) requires a recorded Stormwater Maintenance and Inspection Agreement that transfers from the developer to the Homeowner/Property Owner Association, and Section 803(F) makes this Chapter control over any conflicting County document.