Franklin, TN Environmental Rules: Stormwater Management (2026)
Key Facts
- Catch basins
- Sized for 10-year storm
- Bridges/culverts
- Sized for 50-year storm
- Road flooding limit
- Max 3 inches, half-width, 100-yr event
- Permit required
- Stormwater management permit before construction
- Enforced by
- Franklin city engineer
Summary
Franklin requires new development to size stormwater systems to specific storm-return standards: catch basins for the 10-year storm, bridges and culverts for the 50-year storm, and emergency bypass for a 100-year flood.
New development shall meet a stormwater quantity level of service defined by:(i)Designing road catch basins and connecting culverts to convey the ten-year design-storm runoff. No portion of the storm pipe network shall be surcharged above the interior crown elevation.(ii)Designing bridges, culverts, channels, and cross-drains to pass the 50-year design-storm runoff. No portion of the storm pipe network shall be surcharged above the interior crown elevation.(iii)Providing emergency bypass of the 100-year flood event.(iv)New roadway, existing roadways, and critical service roads are not inundated by more than three inches of water over one-half the roadway width under a 100-year flood event.
Official source re-checked September 7, 2026: no newer edition of the code had been published (publisher’s edition: Code of Ordinances: Supplement 30 Update 1).
Full Breakdown
Franklin Municipal Code § 23-106 sets the design standard for every new development's drainage system: road catch basins and culverts must convey the ten-year storm, bridges and larger culverts must pass the 50-year storm, and roads may flood no more than three inches over half their width in a 100-year event, with emergency bypass required for that event. Section 23-106(2)(a) requires a stormwater management permit, and often a grading permit, from the city engineer before construction, following review of engineer-stamped plans and an environmental site assessment. The ordinance applies citywide under § 23-102 and is administered by the city engineer under the city's NPDES small-MS4 permit.
Violations & Fines
Building or grading without an approved stormwater management permit, or a design that fails the storm-return standards, can trigger a stop-work order and civil penalties from the city engineer.
Frequently Asked Questions
Does Franklin require a stormwater permit for new construction?
What storm event must Franklin's drainage systems handle?
Sources & Official References
Other rules in Franklin
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