(1) Stormwater design or BMP manual.
(a) Adoption. The municipality adopts as its stormwater design and best management practices (BMP) manual the following publications, which are incorporated by reference in this chapter as is fully set out herein:
(1) TDEC Sediment and Erosion Control Handbook; most current edition.
(2) Title 14, Chapter 7, § 14-712.
(3) Tennessee Permanent Stormwater Management and Design Guidance Manual; most current edition.
(4) Other MS4 approved BMP manuals that comply with the goals of the MS4 Permit and/or the Construction General Permit (CGP) may be chosen by the city and a current list is available from the Public Works Department.
(b) These manuals include lists of acceptable BMPs including the specific design performance criteria and operation and maintenance requirements for each stormwater practice. These include city approved BMPs for permanent stormwater management including green infrastructure BMPs. These manuals may be updated and expanded from time to time, at the discretion of the governing body of the municipality, upon the recommendation of the Public Works Department, based on improvements in engineering, science, monitory and local maintenance experience. Stormwater facilities that are designed, constructed and maintained in accordance with these BMP criteria will be presumed to meet the minimum water quality performance standards.
(2) General performance criteria for stormwater management. The following performance criteria shall be addressed for stormwater management at all sites:
(a) All site designs shall control the peak flow rates of stormwater discharge associated with design storms specified in this chapter or as specified by the City of Cookeville Stormwater Management Design Guidelines and reduce the generation of post construction stormwater runoff to pre-construction levels. These practices should seek to utilize pervious areas for stormwater treatment and to infiltrate stormwater runoff from driveways, sidewalks, rooftops, parking lots, and landscaped areas to the maximum extent practical to provide treatment for both water quality and quantity. All stormwater management facilities that are required under § 14-608 of the Cookeville Municipal Code, and the Cookeville Zoning Code and Subdivision Regulations and which are approved after the adoption of this chapter shall be built to control water quality by using the best management practice outlined in this section. Other methods of controlling water quality may be approved by the Director of Public Works if valid documentation is provided which indicates an equivalent or higher level of water quality will result from the alternate method. Due to the city's NPDES MS4 permit stormwater management requirements are periodically changed, therefore specific requirements for detention and water quality will be found in the City of Cookeville Stormwater Management Guidelines.
(b) To protect stream channels from degradation, specific channel protection criteria shall be provided as prescribed in the BMP manual.
(c) Stormwater discharges to critical areas with sensitive resources (i.e., cold water fisheries, swimming areas, recharge areas, water supply reservoirs) may be subject to additional performance criteria, or may need to utilize or restrict certain stormwater management practices.
(d) Stormwater discharges from "hot spots" may require the application of specific structural BMPs and pollution prevention practices. In addition, stormwater from hot spot land use may not be infiltrated.
(e) Prior to or during the site design process, building permit applicants shall consult with the Public Works Department to determine if they are subject to additional stormwater design requirements.
(f) The calculations for determining peak flows as found in the MS4 BMP manual shall be used for sizing all stormwater facilities.
(3) Minimum control requirements.
(a) Stormwater designs shall meet the multi-stage storm frequency storage requirements as identified by the City of Cookeville Stormwater Management Design Guidelines, unless the Public Works Department has granted the applicant a full or partial waiver for a particular BMP under § 14-707.
(b) If hydrologic or topographic conditions warrant greater control than that provided by the minimum control requirements, the Public Works Department may impose any and all additional requirements deemed necessary to control the volume, timing, and rate of runoff.
(4) Permanent stormwater management plan requirements. The stormwater management plan shall include sufficient information to allow the Public Works Department to evaluate the environmental characteristics of the project site, the potential impacts of all proposed development of the site, both present and future, on the water resources, and the effectiveness and acceptability of the measures proposed for managing stormwater generated at the project site. To accomplish this goal the stormwater management plan shall include the following:
(a) Topographic base map: A topographic base map (2 foot contour intervals) to a suitable scale of the site which extends a minimum of 100 feet beyond the limits of the proposed development and indicates:
(1) Existing surface water drainage including streams, ponds, culverts, ditches, sink holes, wetlands, buffers; and the type, size, elevation, etc., of nearest upstream and downstream drainage structures. Riparian buffer zones shall meet the requirements both in accordance with the Tennessee Construction General Permit and with the Buffer Zone Ordinance for the City of Cookeville.
(2) Current land use including all existing structures, locations of utilities, roads, and easements;
(3) All other existing significant natural and artificial features;
(4) Proposed land use with tabulation of the percentage of surface area to be adapted to various uses; drainage patterns; locations of utilities, roads and easements; the limits of clearing and grading;
(b) Proposed structural BMPs;
(c) A written description of the site plan and justification of proposed changes in natural conditions may also be required.
(d) Calculations: Hydrologic and hydraulic design calculations for the pre-development and post-development conditions for the design storms specified in the BMP manual. These calculations must show that the proposed stormwater management measures are capable of controlling runoff from the site in compliance with this chapter and the guidelines of the BMP manual. Such calculations shall include:
(1) A description of the design storm frequency, duration, and intensity where applicable;
(2) Time of concentration;
(3) Soil curve numbers or runoff coefficients including assumed soil moisture conditions;
(4) Peak runoff rates and total runoff volumes for each watershed area;
(5) Infiltration rates, where applicable;
(6) Culvert, stormwater sewer, ditch and/or other stormwater conveyance capacities;
(7) Flow velocities;
(8) Data on the increase in rate and volume of runoff for the design storms referenced in the BMP manual; and
(9) Documentation of sources for all computation methods and field test results.
(e) Soils information: If a stormwater management control measure depends on the hydrologic properties of soils (e.g., infiltration basins), then a soils report shall be submitted. The soils report shall be based on on-site boring logs or soil pit profiles and soil survey reports. The number and location of required soil borings or soil pits shall be determined based on what is needed to determine the suitability and distribution of soil types present at the location of the control measure.
(f) Maintenance and repair plan: The design and planning of all stormwater management facilities shall include detailed maintenance and repair procedures to ensure their continued performance. These plans will identify the parts or components of a stormwater management facility that need to be maintained and the equipment and skills or training necessary. Provisions for the periodic review and evaluation of the effectiveness of the maintenance program and the need for revisions or additional maintenance procedures shall be included in the plan.
(g) Landscaping plan: The applicant must present a detailed plan for management of vegetation at the site after construction is finished, including who will be responsible for the maintenance of vegetation at the site and what practices will be employed to ensure that adequate vegetative cover is preserved. Where it is required by the BMP, this plan must be prepared by a registered landscape architect licensed in Tennessee.
(h) Maintenance easements: The applicant must ensure access to the site for the purpose of inspection and repair by securing all the maintenance easements needed. These easements must be binding on the current property owner and all subsequent owners of the property and must be properly recorded in the land record.
(i) Maintenance agreement:
(1) Stormwater facilities on properties permitted under the requirements of this chapter are required to provide a maintenance agreement that runs with the land. The owner of property must execute an inspection and maintenance agreement that shall operate as a deed restriction binding on the current property owner and all subsequent property owners and their lessees and assigns, including but not limited to, homeowner associations or other groups or entities.
(2) The maintenance agreement shall:
(a) Assign responsibility for the maintenance and repair of the stormwater facility to the owner of the property upon which the facility is located and be recorded as such on the plat for the property by appropriate notation.
(b) Provide for periodic inspection by the property owner in accordance with the requirements of subsection (3) below for the purpose of documenting maintenance and repair needs and to ensure compliance with the requirements of this chapter. The property owners will arrange for professional inspections in accordance with the requirements of subsection (3) below on a less frequent schedule, to be conducted by a licensed professional engineer or landscape architect, registered to practice in the State of Tennessee, who will submit a signed written report of the inspection to the Public Works Department. It shall also grant permission to the city to enter the property at reasonable times and to inspect the stormwater facility to ensure that it is being properly maintained.
(c) Provide that the minimum maintenance and repair needs include, but are not limited to: the removal of silt, litter and other debris, the cutting of grass, grass cuttings and vegetation removal, and the replacement of landscape vegetation, in detention and retention basins, and inlets and drainage pipes and any other stormwater facilities. It shall also provide that the property owner shall be responsible for additional maintenance and repair needs consistent with the needs and standards outlined in the BMP manual.
(d) Provide that maintenance needs must be addressed in a timely manner.
(e) Provide that if the property is not maintained or repaired within the prescribed schedule, the Public Works Department shall perform the maintenance and repair at its expense, and bill the same to the property owner. The maintenance agreement shall also provide that the Public Works Department's cost of performing the maintenance shall be a lien against the property.
(3) Inspections required for stormwater management facilities that have a recorded maintenance agreement - generally. The owners and/or the operators of stormwater management facilities shall:
(a) Perform routine inspections to ensure that the BMPs are properly functioning. These inspections shall be conducted on an annual basis, at a minimum. These inspections shall be conducted by a person familiar with control measures implemented at the site. Owners or operators shall maintain documentation of these inspections. The Public Works Department may require submittal of this documentation.
(b) Perform comprehensive inspection of all stormwater management facilities and practices. Such inspection shall be conducted once every five years, at a minimum. Such inspections must be conducted by either a professional engineer or landscape architect, licensed in the State of Tennessee. Complete inspection reports for these five year inspections shall include:
(i) Facility type,
(ii) Inspection date,
(iii) Latitude and longitude and nearest street address,
(iv) BMP owner information (e.g. name, address, phone number, fax, and email)
(v) A description of BMP condition including: vegetation and soils; inlet and outlet channels and structures; embankments, slopes and safety benches; spillways, weirs, and other control structures; and any sediment and debris accumulation,
(vi) Photographic documentation of BMPs, and
(vii) Specific maintenance items or violations that need to be corrected by the BMP owner along with deadlines and re-inspection dates.
(c) Owners or operators shall maintain documentation of these inspections. The Public Works Department may require submittal of this documentation.
(5) Sediment and erosion control plans: The applicant must prepare a sediment and erosion control plan for all construction activities that complies with § 14-704
(6) below.
(6) Sediment and erosion control plan requirements. The requirements of Cookeville Municipal Code, Title 14, Chapter 5
, entitled "Erosion and Sediment Control Regulations", shall be met. (as added by Ord. #004-06-11, July 2004, and amended by Ord. #015-01-01, February 2015, and Ord. #O24-06-18, July 2024)