The City of Kingsport regulation is compliant with the National Pollutant Discharge Elimination System (NPDES) through municipal regulation Kingsport Code of Ordinances Chapter 38 Article III. The city’s Municipal Separate Storm Sewer System (MS4) requires Kingsport to administer and enforce compliance with stormwater discharge permits in an effort to decrease stormwater pollutants and increase overall water quality. Kingsport is a Qualifying Local Program (QLP) participant, which means that there is a streamlined process in place when a permittee has submitted “a program specific Notice of Intent (NOI) to a participating QLP, and has obtained a Notice of Coverage (NOC), the operator of the construction activity is authorized to discharge under the CGP without the submittal of an NOI, Stormwater Pollution Prevention Plan (SWPPP), or related permit fee to the division.”
Sec. 38-169. - Design criteria.
(a) All developments that must submit a stormwater management plan shall provide water quality treatment in accordance with the following requirements:
(1) Stormwater runoff from the development site must be treated for water quality prior to discharge from the development site in accordance with the stormwater treatment standards and criteria provided in the manual.
(2) Water quality treatment shall be achieved through the use of one or more structural and/or nonstructural SCMs that are designed and constructed in accordance with the criteria, guidance, and specifications provided in the manual.
(3) Stormwater quality control methods, designs or technologies not provided in the manual may be submitted for approval if it is proven that such alternatives will meet or exceed the water quality control requirements set forth in the manual and this chapter.
(4) SCMs shall not be installed within public rights-of-way or on public property without prior approval of the director.
(b) All developments that must submit a plan shall provide downstream channel protection using the design criteria and guidance provided in section 3.4 of the manual.
(c) All developments that must submit a plan shall provide a downstream impact analysis addressing overbank flood control in accordance with section 3.5 of the manual.
(d) All developments that must submit a plan shall establish, protect and maintain a buffer zone, in accordance with the policies criteria and guidance set forth in the manual. Exemptions from this requirement are as follows:
(1) The perimeter of waterbodies that have no known connection to streams, other ponds, lakes or wetlands.
(2) Stormwater management facilities or BMPs that are designed, constructed and maintained for the purposes of stormwater quality and/or quantity control, unless expressly required by the design standards and criteria for the facility are provided in the manual.
(e) In addition to the requirements set forth in subsections (a) through (d) of this section, all developments that must submit a stormwater management plan shall include the following:
(1) Account for both on-site and off-site stormwater;
(2) Maintain natural drainage divides and hydrologic characteristics;
(3) Provide soils information; and
(4) Control stormwater runoff and provide peak discharge/volume control in accordance with this article using:
a. Predeveloped conditions unless otherwise specified by the director;
b. NOAA Atlas 14 rainfall data;
c. Post-development versus pre-development hydrologic/hydraulic modeling that shows attenuation of developed site runoff. Developed discharge from a site shall be less than or equal to pre-development discharge for the 2 year through 100-year design storms;
d. Longitudinal storm drains designed for a ten-year frequency storm, provided that no residential or commercial structures are flooded by a 100-year frequency storm;
e. Roadway cross drains designed for a ten-year frequency storm for a local street and 100-year frequency storm for a collector street, provided no residential or commercial structures are flooded by the 100-year frequency storm. All pipes lying under the roadway shall be reinforced concrete unless otherwise approved by the director;
f. Drainage easements delineating the 100-year frequency storm flood fringe to prevent flooding and future disturbance; and
g. Pipe materials approved by the director.
(f) Pursuant to the City of Kingsport Zoning Ordinance, a floodplain development permit is required for all development or redevelopment within federally designated floodplains as shown on the applicable FEMA flood insurance rate map(s) of latest issue.
(g) The rational method shall be used to determine peak flow rates only. National Resource Conservation Service (NRCS) methods and those provided in the manual for water quality and channel protection shall be used in determining storage requirements.
(h) All supporting hydrologic and hydraulic assumptions shall be submitted, as well as all maps and references used in calculations.
(i) The design must not adversely affect adjacent or neighboring properties.
(j) The city may allow stormwater control measures to be implemented at another location within the same USGS 12-digit hydrologic unit code (HUC) watershed as the original project. Off-site mitigation must treat a minimum of 1.5 times the amount of water not treated on site. The off-site mitigation location must be approved by the city.
(k) If the project cannot meet pollutant removal standards, and cannot provide for off-site mitigation, the city may allow the owner to make payment in a public stormwater project fund at a level sufficient to design, install, and maintain the stormwater mitigation measures.
Sec. 38-170. - Exemptions.
(a) Developments that conform to the criteria in subsection (c) of this section are exempt from the requirements of this chapter, unless the director has determined that stormwater quality management is needed to satisfy local or state NPDES, TMDL or other regulatory water quality requirements, or the proposed development will be a pollutant hotspot, or to limit adverse stormwater quality or channel protection impacts of the proposed development.
(b) The exemptions listed in subsection (c) of this section shall not be construed as exempting these developments from compliance with stormwater requirements stated in the minimum subdivision regulations, chapter 114, pertaining to zoning, or other city regulations.
(c) The following developments are exempt from the requirements for a stormwater management plan:
(1) Residential or nonresidential developments that disturb less than one acre of land and are not part of a larger common plan of development or sale that would disturb one acre or more;
(2) Minor land disturbing activities such as residential gardens and residential or nonresidential repairs, landscaping or maintenance work;
(3) Individual utility service connections, unless such activity is carried out in conjunction with the clearing, grading, excavating, transporting, or filling of a lot for which a plan would otherwise be required;
(4) Installation, maintenance or repair of individual septic tank lines or drainage fields, unless such activity is carried out in conjunction with the clearing, grading, excavating, transporting or filling of a lot for which a plan would otherwise be required;
(5) Installation of posts or poles;
(6) Farming activities, existing nursery and agricultural operations, but not including construction conducted as a permitted principal or accessory use by chapter 114, zoning;
(7) Emergency work to protect life, limb or property, and emergency repairs, provided that the land area disturbed shall be shaped and stabilized in accordance with city requirements as soon as practicable;
(8) Additions or modifications to existing, individual, single-family structures;
(9) Silvicultural activities; and
(10) State and federal projects subject to the submission requirements of TDEC.
(Ord. No. 6632, § I, 12-20-2016)
Sec. 38-254. - Requirements.
(a) The owners of stormwater management facilities, BMPs, buffer zones and water quality volume credit areas shall at all times inspect, properly operate and maintain all facilities and systems of stormwater treatment and control (and related appurtenances), and all buffer zones and water quality volume credit areas in such a manner as to maintain the full function of the facilities or BMP's which are installed or used by the owners to achieve compliance with this article.
(b) Inspection and maintenance of privately owned stormwater management facilities, BMP's, buffer zones and water quality volume credit areas shall be performed at the sole cost and expense of the owners of such facilities/areas.
(c) Inspection and maintenance shall be performed in accordance with specific requirements and guidance provided in the manual. Inspection and maintenance activities shall be documented by the owner or their designee, and such documentation shall be maintained by the owner for a minimum of three years, and shall be made available for review by the director upon request.
(d) The director has the authority to impose more stringent inspection requirements as necessary for purposes of water quality protection and public safety.
(f) The removal of sediment and/or other debris from stormwater management facilities and BMP's shall be performed in accordance with all city, state, and federal laws. Guidelines for sediment removal and disposal are referenced in the manual. The director may stipulate additional guidelines if deemed necessary for public safety.
(g) The director may order corrective actions as are necessary to properly maintain and operate erosion prevention and sediment control measures, BMP's stormwater management facilities, buffer zones and/or water quality volume credit areas within the city for the purposes of stormwater pollution prevention, water quality treatment, channel erosion protection, adherence to local performance standards and/or public safety. If the owner fails to perform corrective actions, the director shall have the authority to order the city or others to take corrective actions. In such cases where a performance bond exists, the city shall utilize the bond to perform the corrective actions. In such cases where a performance bond does not exist, the owner shall reimburse the city for all of its direct and related expenses. If the owner fails to reimburse the city, the city is authorized to file a lien for said costs against the property and to enforce the lien by judicial foreclosure proceedings.
(h) This article does not authorize access to adjoining private property by the owner or site operator. Arrangements concerning removal of sediment or pollutants on adjoining property must be settled by the owner or operator with the adjoining land owner.
NPDES Stormwater Permitting Program
Tennessee Permanent Stormwater Management and Design Guidance Manual
Stormwater Management Ordinance