The City of Goodlettsville's Stormwater Policy

As you may already know the City of Goodlettsville has implemented a new Stormwater Management Ordinance. With the new requirements of this Ordinance comes an opportunity to reevaluate and restructure the methodology of how we handle the responsibility for Erosion Prevention and Sediment Controls (EP & SC) for development.

Development that disturbs more than one acre of land (and less than one acre if, in the discretion of the Administrator, such activity poses a unique threat to water, or public health or safety) will be required to obtain a Land Disturbance Permit. The applicant must also have an approved Stormwater Management Plan and Sediment & Erosion Control Plan for the site. This Permit must be applied for at Goodlettsville Public Works, 215 Cartwright Street, Goodlettsville, TN 37072 (615) 859-2740.

Prior to obtaining a Goodlettsville permit, the applicant must obtain all necessary stormwater permits from the Tennessee Department of Environment & Conservation (TDEC) and provide copies of same.

All development that incorporates stormwater quality Best Management Practices (BMPs) is also required to execute an Inspection and Maintenance Agreement.

Development that disturbs more than 5,000 square feet of land use, is less than one acre, and all new single family home construction, will be required to have erosion control fencing and construction exits. A Residential Building Lot Erosion Prevention and Sediment Control checklist for these requirements is available at Goodlettsville Codes Department, 117 Memorial Drive, Goodlettsville, TN 37072. (615) 851-3746.

The mud, sediment, gravel and landscape material leaving the construction site washes into storm drains clogging them and reducing flow capacity of streams which can adversely affect areas that are prone to flooding. These systems drain into local waterways and the resulting sedimentation chokes out wetlands and aquatic life and harms water quality. Sediment is the number one source of water pollution in the State and many streams are considered “impacted” by sediment. One of the major sources is construction sites according to Tennessee Department of Environment and Conservation. These construction sites become a nuisance to local residents and the general public – carrying mud into streets, garages and houses.

The City of Goodlettsville adopted as its stormwater design and Best Management Practices (BMP) manual based on the following publications:

TDEC Sediment and Erosion Control Manual
http://www.state.tn.us/environment/wpc/sed_ero_controlhandbook/

Tennessee Water Resources Research Center Manual for Post Construction
http://eerc.ra.utk.edu/divisions/wrrc/BMP/bmp.htm

Stormwater Design or BMP Manual.

1. Adoption.  The City of Goodlettsville adopts as its stormwater design and best management practices (BMP) Manual, the following publications, which are incorporated by reference in this ordinance as is fully set out herein:
   1. TDEC Sediment and Erosion Control Manual
   2. Tennessee Water Resources Research Center Manual for Post Construction
2. This Manual includes a list of acceptable BMPs including the specific design performance criteria and operations and maintenance requirements for each stormwater practice.  The Manual may be updated and expanded from time-to-time by the Administrator.  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.

General Performance Criteria for Stormwater Management.

Unless granted a waiver or judged by the Administrator to be exempt, the following performance criteria shall be addressed for stormwater management at all sites:

1. All site designed shall control the peak flow rates of stormwater discharge associated with design storms specified in this ordinance or in the BMP Manual and reduce the generation of post-construction stormwater runoff to pre-construction levels.  These practices should seek to utilize previous 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.
2. To protect stream channels from degradation, specific channel protection criteria shall be provided as prescribed in the BMP Manual.
3. Stormwater discharges to critical areas with sensitive resources (i.e., cold water fisheries, shellfish beds, swimming beaches, recharge areas, water supply reservoirs, etc.) may be subject to additional performance criteria, or may need to utilize or restrict certain stormwater management practices.
4. Stormwater discharges from “hot spots” may require the application of specific structural BMPs and pollution prevention practices.
5. Prior to or during the site design process, applicants for Land Disturbance Permits shall consult with the Administrator to determine if they are subject to additional stormwater design requirements.
6. The calculations for determining peak flows as found in the BMP Manual shall be used for sizing all stormwater facilities.

Minimum Control Requirements.

Stormwater Management Plan Requirements.

The stormwater management plan shall include sufficient information to allow the Administrator 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:

1. Topographic Base Map:  A topographic base map of the site which extends beyond the limits of the proposed development and indicates:
   1. Existing surface water drainage including streams, ponds, culverts, ditches, sink holes, wetlands; and the type, size, elevation, etc. of the nearest upstream and downstream drainage structures.
   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.
   5. Proposed structural BMPs;
   6. A written description of the site plan and justification of proposed changes in natural conditions.
2. 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 ordinance 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.
3. 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.
4. 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 needs 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.  A permanent elevation benchmark shall be identified in the plans to assist in the periodic inspection of the facility.
5. 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.
6. 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.
7. Maintenance Agreement:  The owner of the property to be served by an on-site stormwater management facility 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.  The Maintenance Agreement shall:
   1. 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.
   2. Provide for a periodic inspection by the property owner for the purpose of documenting maintenance and repair needs and ensure compliance with the purpose and requirements of this ordinance.  The property owner will arrange for this inspection to be conducted by a registered professional engineer licensed to practice in the State of Tennessee who will submit a sealed report of the inspection to the Administrator. 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.
   3. 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, 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.
   4. Provide that maintenance needs must be addressed in a timely manner which is on a schedule to be determined by the Administrator.
   5. Provide that if the property is not maintained or repaired within the prescribed schedule, the Administrator 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 City’s cost of performing the maintenance shall be a lien against the property.
8. The municipality shall have the discretion to accept the dedication of any existing or future stormwater management facility, provided such facility meets the requirements of this Ordinance and includes adequate, perpetual access and sufficient areas, by easement or otherwise, for inspection and regular maintenance.  Any stormwater facility accepted by the municipality must also meet the municipality’s construction standards and any other standards and specifications that apply to the particular stormwater facility in question.
9. Sediment and Erosion Control Plans:  The applicant must prepare a Sediment and Erosion Control Plan for all construction activities that complies with §18.306(5) below.

Sediment and Erosion Control Plan requirements.

The Sediment and Erosion Control Plan shall accurately describe the potential for soil erosion and sedimentation problems resulting from land-disturbing activity and shall explain and illustrate the measures that are to be taken to control these problems.  The length and complexity of the plan is to be commensurate with the size of the project, severity of the site condition, and potential for off-site damage.  The plan shall be sealed by a registered professional engineer licensed in the State of Tennessee.  The plan shall also conform to the requirements found in the BMP Manual and shall include at least the following:

1. Project Description:  Briefly describe the intended project and proposed land-disturbing activity including number of units and structures to be constructed and infrastructure required.
2. A topographic map with contour intervals of two (2) feet or less showing present conditions and proposed contours resulting from land-disturbing activity.
3. All existing drainage ways, including intermittent and wet-weather.  Include any designated floodways or flood plains.
4. A general description of existing land cover.  Individual trees and shrubs do not need to be identified.
5. Stands of existing trees as they are to be preserved upon project completion, specifying their general location on the property.  Differentiation shall be made between existing trees to be preserved, trees to be removed and proposed planted trees.  Tree protection measures must be identified and the diameter of the area involved must also be identified on the plan and shown to scale.  Information shall be supplied concerning the proposed destruction of exceptional and historic trees in setbacks and buffer strips, where they exist.  Complete landscape plans may be submitted separately.  The plan must include the sequence of implementation for tree protection matters.
6. Approximate limits of proposed clearing, grading and filling.
7. Approximate flows of existing stormwater leaving any portion of the site.
8. A general description of existing soil types and characteristics and any anticipated soil erosion and sedimentation problems resulting from existing characteristics.
9. Location, size and layout of proposed stormwater and sedimentation control improvements.
10. Proposed drainage network.
11. Proposed drain tile or waterway sizes.
12. Approximate flows leaving the site after construction and incorporating water run-off mitigation measures.  The evaluation must include projected effects on property adjoining the site and on existing drainage facilities and systems.  The plan must address the adequacy of outfalls from the development - when water is concentrated, what is the capacity of waterways, if any, accepting stormwater off-site; and what measures, including infiltration, sheeting into buffers, etc., are going to be used to prevent the scouring of waterways and drainage areas off-site, etc.
13. The projected sequence of work represented by the grading, drainage and sedimentation and erosion control plans as related to other major items of construction, beginning with the initiation of excavation and including the construction of any sediment basins or retention facilities or any other structural BMPs.
14. Specific remediation measures to prevent erosion and sedimentation run-off.  Plans shall include detailed drawings of all control measures used; stabilization measures including vegetation and non-vegetation measures, both temporary and permanent, will be detailed.  Detailed construction notes and a maintenance schedule shall be included for all control measures in the plan.
15. Specific details for the construction of rock pads, wash-down pads, and settling basins for controlling erosion; road access points; eliminating or keeping soil, sediment, and debris on streets and public ways at a level acceptable to the Administrator.  Soil, sediment, and debris brought onto streets and public ways must be removed by the end of the work day by machine, broom or shovel to the satisfaction of the Administrator.  Failure to remove the sediment, soil or debris shall be deemed a violation of this Ordinance.
16. Proposed structures; location (to the extent possible) and identification of any proposed additional buildings, structures or development on the site.
17. A description of on-site measures to be taken to recharge surface water into the ground water system through infiltration.

If you have any questions, please contact the City of Goodlettsville Public Works Department by calling (615) 859-2740 or via email.