(A) The goal of the water quality buffer is to preserve undisturbed vegetation that is native to the streamside habitat in the area of the project. Vegetated, preferably native, water quality buffers protect water bodies by providing structural integrity and canopy cover, as well as stormwater infiltration, filtration and evapotranspiration.
(B) The buffer width depends on the size of a drainage area. Streams or other waters with drainage areas less than one square mile will require buffer widths of 30 feet minimum. Streams or other waters with drainage areas greater than one square mile will require buffer widths of 60 feet minimum. The 30-feet criterion for the width of the 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 15 feet at any measured location. The 60-feet criterion for the width of the 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 30 feet at any measured location. The Town Engineer shall determine the circumstances under which the average will be available. A determination that standards cannot be met may not be based solely on the difficulty or cost associated with implementation. Every attempt should be made for development and redevelopment activities not to take place within the buffer zone.
(C) If water quality buffer width as defined above cannot be fully accomplished on-site, the Town Engineer shall determine the circumstances under which alternative buffer widths will be available. A determination that water quality buffer widths cannot be met on site may not be based solely on the difficulty or cost of associated with implementation, but must include multiple criteria, such as type of project, existing land use and physical conditions that preclude use of these practices.
(D) Buffer zones are not primary sediment control measures and should not be relied upon as such.
(E) Rehabilitation and enhancement of a natural buffer zone is allowed, if necessary, for improvement of its effectiveness of protection of the waters of the state.
(F) Water quality buffers shall be clearly marked on site development plans, grading permit applications, and/or concept plans.
(G) Buffer zone requirements.
(1) Construction applies to all streams adjacent to construction sites, with an exception for streams designated as impaired or exceptional Tennessee waters, as designated by the Tennessee Department of Environment and Conservation. A 30-foot natural riparian buffer zone adjacent to all streams at the construction site shall be preserved, to the maximum extent practicable, during construction activities at the site. The water quality buffer zone is required to protect waters of the state located within or immediately adjacent to the boundaries of the project, as identified using methodology from standard operating procedures for hydrologic determinations (see rules to implement a certification program for qualified hydrologic professionals, TN Rules Chapter 0400-40-17). The buffer zone requirement only applies to new construction sites. The riparian buffer zone should be preserved between the top of stream bank and the disturbed construction area. The 30-feet criterion for the width of the 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 15 feet at any measured location.
(2) Buffer zone requirements for discharges into impaired or exceptional Tennessee waters. A 60-foot natural riparian buffer zone adjacent to the receiving stream designated as impaired or high quality waters shall be preserved, to the maximum extent practicable, during construction activities at the site. The water quality buffer zone is required to protect waters of the state (e.g., perennial and intermittent streams, rivers, lakes, wetlands) located within or immediately adjacent to the boundaries of the project, as identified on a 7.5-minute USGS quadrangle map, or as determined by the director. Buffer zones are not sediment control measures and should not be relied upon as primary sediment control measures. Rehabilitation and enhancement of a natural buffer zone is allowed, if necessary, for improvement of its effectiveness of protection of the waters of the state. The buffer zone requirement only applies to new construction sites. The riparian buffer zone should be established between the top of stream bank and the disturbed construction area. The 60-feet criterion for the width of the 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 30 feet at any measured location.
(3) Permanent new development and significant redevelopment sites are required to preserve water quality buffers along streams within the MS4. Alternatives to installing new or expanding existing buffer zones may be considered on a case-by-case basis for redevelopment sites. Buffers shall be clearly marked on site development plans, grading permit applications, and/or concept plans. Buffer width depends on the size of a drainage area. Streams or other waters with drainage areas less than one square mile will require buffer widths of 30 feet minimum. The 30-feet criterion for the width of the 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 15 feet at any measured location. Streams or other waters with drainage areas greater than one square mile will require buffer widths of 60 feet minimum. The 60-feet criterion for the width of the 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 30 feet at any measured location.
(Ord. 2012-18, passed 11-12-12)