Collierville, TN Environmental Rules: Stormwater Management (2026)

Chapter 152 of the Collierville Code of Ordinances applies to all land development and construction activities, including site plan and subdivision applications. Under § 152.201 the standards reach any new development or redevelopment site with land development activities of one acre or more. A project under one acre can still be pulled in if its discharge is likely to contribute to a violation of a state water quality standard, if it is a hotspot land use, or if it is part of a larger common plan of development.

The core standard is § 152.207: the first inch of rainfall from an event preceded by 72 hours of no measurable precipitation must be infiltrated, evapotranspired, harvested or used, and that first inch must be 100% managed. Where a site cannot meet 100%, the remainder must be treated before discharge with a technology documented to remove 80% total suspended solids. A developer can instead mitigate off site, at a minimum of 1.5 times the amount of water not managed on site, or pay into a public stormwater project fund set at 1.5 times the estimated cost of on-site controls. Acceptance of that payment is not automatic and is decided case by case. Under § 152.208 the Town can approve a 10% reduction in the volume to be managed for redevelopment, for density that exceeds seven units per acre, or for a Floor to Area Ratio of two, with a maximum reduction of 30%.

Quantity control sits alongside quality control. Section 152.202(D) requires a permanent stormwater storage facility unless the Town Engineer finds an exception applies, and § 152.202(E) caps the release rate at the pre-development peak rate for the two-year, ten-year and 25-year storm events. The design manuals incorporated by reference are the TDEC Erosion Prevention and Sediment Control Handbook and the Town of Collierville Stormwater Drainage Manual. Section 152.203 requires a stormwater management plan, starting with a topographic base map that extends a minimum of 100 feet beyond the limits of the proposed development.