Athens City Code
Source snapshot: 2026-09-15. Check the municipal source for later changes. Municipal source ↗ · Download full document · Markdown
Contents14-130 Permanent Stormwater Management: Design And Construction Inspection
14-130 Permanent Stormwater Management: Design And Construction Inspection
Original section ↗ · Link to this section
- (1) In order to comply with the City’s permanent stormwater standards for new development and redevelopment projects, operators shall design and install SCMs as established by Tennessee Rule 0400-40-10-.04 and comply with other requirements of Tennessee Rule 0400-40-10-.04.
- (2) The Post Construction/Permanent water quality design storm is a 1-year, 24-hour storm event. Actual project WQTV requirements shall be based on the proposed permanent SCM treatment type as outlined in 4.2.5.2 of the Small MS4 General Permit NPDES Permit TNS000000.
- (3) SCMs must be designed to provide full treatment capacity within 72 hours following the end of the preceding rain event for the life of the new development or redevelopment project. The operator may use any design manuals approved as part of the City’s BMP Manual.
- (4) Total suspended solids (TSS) removal rate shall be the City’s recognized metric for the reduction of pollutants in stormwater effluent. Design TSS removal rates for approved MTDs shall be established by a 3rd party certification program recognized by the City. The two certification programs currently recognized by the City include NJDEP and WSDOE; additionally, use of sequential MTDs, e.g. a treatment train of two or more HDS units, in an attempt to cumulatively meet the 80% TSS requirements are not recognized as achieving such and shall not be permissible in permanent SCM design(s).
- (5) Post Construction/permanent water quantity SCMs shall be designed to attenuate post-construction peak flows from the 2-year 24-hour event through the 100-year 24-hour storm event to equal or less than pre-development peak flows for all new development and redevelopment projects.
- (6) Water Quality Riparian Buffers - Post Construction/Permanent water quality riparian buffers shall be those buffers defined in 14-502 above and shall meet the requirements described in this ordinance. The criteria for the width of the post construction/permanent buffer zone can be established on an average width basis at a project, as long as the minimum width of the buffer zone is more than the required minimum width at any measured location. If the new development or redevelopment site encompasses both sides of a stream, buffer averaging can be applied to both sides, but must be applied independently. Water quality riparian buffer widths are measured from the top of bank also referred to as the “ordinary high-water mark.” Stormwater discharges should enter the post construction/permanent water quality riparian buffer as sheet flow, not as concentrated flow, where site conditions allow.
- (7) Post Construction/Permanent buffers for waters with available parameters for siltation or habitat alteration or unassessed waters:
- (a) Average buffer width: 30 feet.
- (b) Minimum buffer width: 15 feet.
- (8) Post Construction/Permanent buffers for Exceptional Tennessee Waters or waters with unavailable parameters for siltation or habitat alteration:
- (a) Average buffer width: 60 feet.
- (b) Minimum buffer width: 30 feet
- (9) The designer/operator must comply with the vegetation requirements and the permissible land uses set forth for buffers in the MS4 permit.