Franklin, TN Environmental Rules: Grading & Drainage (2026)

Franklin's grading and drainage controls sit at the intersection of Title 23 (Stormwater Management) of the Franklin Municipal Code, the City's Subdivision Regulations, and the TDEC NPDES Construction General Permit TNR100000 administered by Franklin as a Qualified Local Program. Section 23-101 (Green Stormwater Infrastructure) is the centerpiece: starting January 1, 2014, all new development and all redevelopment in Franklin that disturbs one acre or more must incorporate green infrastructure practices and reduce stormwater runoff using methods specified in the City's runoff-reduction guidance. The City uses the small-storm runoff reduction approach to drive infiltration, evapotranspiration, and rainwater harvesting on each site. Alternative practices may be approved by the City Engineer only when site-specific physical constraints exist — for example, groundwater pollution risk, soil contamination, or utility conflicts. Section 23-101 explicitly states that cost and difficulty alone are NOT valid grounds for an exemption. Post-construction BMPs are subject to a maintenance agreement recorded against the property, and BMP performance is inspected by the City on a defined cycle. Site plans for grading, drainage, and BMP design must be submitted to the Engineering Department with stormwater management plans and (for sites greater than or equal to one acre) a SWPPP under TNR100000. The Franklin Engineering Department reviews drainage to confirm that on-site detention does not increase peak discharge to downstream properties — particularly important given that downstream of nearly every Franklin site flows to the Harpeth River or its tributaries. Stormwater user fees fund the program, calculated against an Equivalent Residential Unit (ERU) of 3,350 square feet of impervious area.