Planning Department

Conservation Subdivisions

CHAPTER 4.

Note: This chapter partially relies on Zoning text amendments not yet adopted. As a placeholder Zoning Code sections are referred to as "Section 17.12.xx". Once the text amendments are adopted, the xx will be replaced and this note deleted.

4-1 Purpose

  1. Purpose. Conservation Subdivisions enable a development that groups units on the more buildable portion of a tract, while preserving at least 50 percent of the tract including natural drainage systems, open space, and environmentally and culturally sensitive areas. The purpose of Conservation Subdivisions is to:
    1. Provide for the preservation of open space as a watershed protection measure.
    2. Permit flexibility of design in order to promote environmentally sensitive and efficient use of the land
    3. Preserve in perpetuity:
      1. Unique or sensitive natural resources such as groundwater, floodplains and floodways, wetlands, streams, steep slopes, woodlands and wildlife corridors and habitat.
      2. Scenic views.
      3. Historic and archaeological sites.
    4. Permit grouping of houses and structures on less environmentally sensitive soils that will reduce the amount of infrastructure, including paved surfaces and utility easements, necessary for residential development.
    5. Minimize land disturbance and removal of vegetation during construction resulting in reduced erosion and sedimentation.
    6. Promote interconnected greenways and wildlife and other natural corridors through the community.
4-2 Applicability
  1. Applicability. Conservation Subdivisions shall be permitted in areas designated as Rural, Natural Conservation or Interim Non-Urban land use policy category in a Community Plan.
  2. Additional Applicable Land Use Policy Categories. The Planning Commission may permit Conservation Subdivisions in other land use policy categories.
  3. Zoning Code Requirements. Conservation Subdivisions are subject to the requirements of Section 17.12.xx Lot Options for Conservation Subdivisions of the Zoning Code.
4-3 Minimum Area of Subdivision
  1. Minimum Area. The minimum area of the subdivision shall be no less than ten times the minimum lot area for the base-zoning district as established by Table 17.12.020.A of the Zoning Code.
  2. Waiver of the Minimum Area Requirement. The Planning Commission may consider a smaller area than required in Section 4-3.1 if the applicant can demonstrate one of the following:
    1. The proposed Conservation Lands provide a connection between unconnected, existing areas of open space or other protected areas and shall not result in providing only narrow or isolated fragments of Conservation Lands.
    2. The Conservation Subdivision would ensure a unique natural, cultural or historical area will be protected.
4-4 Approval Procedures
  1. Required Pre-Application Conference. Approval of Conservation Subdivisions shall follow the Procedures for Plat Approval set out in Chapter 2 of these regulations. For Conservation Subdivisions, the pre-application conference in Section 2-3.1 shall be required.
  2. Planning Commission Review. The Planning Commission shall review a proposed Conservation Subdivision and shall make a determination that the proposal:
    1. Conforms to and is consistent with the purpose of the Conservation Subdivision as described in the Section 4-1.
    2. Conforms to and is consistent with the principles and objectives of the General Plan.
    3. Provides sufficient protection for the lands designated as Conservation Lands.
  3. Quality of the Conservation Lands. The Planning Commission shall make a determination that the quality of the lands designated as Conservation Lands merit the use of Chapter 5 to develop the subdivision.
  4. Specific Limitations and Requirements. The Planning Commission may impose specific limitations and requirements, including any not addressed by these regulations, so as to ensure that the proposed development, including, but not limited to design of the proposed structures and locations of the building lots, respects the unique character of the resources to be conserved as Conservation Lands, the abutting land uses, and the larger community in which the property is located.
  5. Additional Requirements and Review for the Concept Plan. In addition to standard subdivision review, review of the concept plan for a Conservation Subdivision shall include:
    1. Survey and marking of the boundaries of the areas to be included as Conservation Lands as described in Sections 4-7.1 - 4-7.3 as well as all phasing boundaries.
    2. Location of all areas proposed for grading and other land disturbance with respect to notable features of natural, historical, or cultural significance identified by the applicant as part of the existing conditions submission.
    3. Proposal for minimization and mitigation of development impacts on resources to be conserved.
    4. Impact of proposed development on the identified cultural and natural resources.
    5. Suitability of the proposed areas to provide additions to the existing open space network and greenway systems and to provide terminal vistas, parks, green spaces and other open spaces.
    6. Proposal for conservation easements and dedications.
    7. If applicable, proposal for preservation of farmland.
    8. Delineation of alternative lot size standards to be employed.
    9. Preliminary Conservation Ownership and Management Plan outlining the entities proposed to be responsible for maintaining various elements of the property and describing proposed management objectives and techniques.
  6. Additional Requirements and Review for the Development Plan. In addition to the development plan requirements listed in Chapter 2, a description of the measures to be taken to minimize and control adverse impacts on the Conservation Lands during and following the period of site disturbance and construction shall be required.
  7. Additional Requirements and Review for the Final Subdivision Plat. In addition to the final plat requirements listed in Chapter 2, a Final Conservation Ownership and Management Plan, detailing the precise boundaries and exact acreage of all proposed Conservation Lands and the entities to be responsible for maintaining various elements of the property and describing proposed management objectives and techniques shall be required. Conservation Lands shall be shown as open space on the Final Plat.
4-5 Lot Yield
  1. Lot Yield. To determine the maximum density of the Conservation Subdivision, divide the percent of the gross land area by the minimum lot area of the actual zone district as described in Section 17.12.xx of the Zoning Code.
4-6 Lot Requirements
  1. Lot Dimensions. The lot dimensions shall be as described in Section 17.12.xx of the Zoning Code.
  2. Lot Frontage. Each lot shall have frontage on a street or onto a common open space. The street frontage on the common open space shall be of sufficient width to allow direct pedestrian access from each lot to the street. Lots fronting onto a common open space shall have convenient vehicular access to a street or to a permanent easement via an alley or shared driveway. All alleys in Conservation Subdivisions are subject to the requirements of Section 4-9.4.
  3. Lot Frontage on an Open Space. The Planning Commission may consider a Conservation Subdivision with lots fronting onto an open space with vehicular access from an alley, as illustrated in Figure 4-1. All such alleys shall meet the requirements of the Public Works Department and the Fire Marshal. All alleys in Conservation Subdivisions are subject to the requirements of Section 4-9.4.

    Figure 4-1: Lot Frontage on an Open Space
  4. Multiple Lots on a Common Access Easement. Multiple lots may share a common access easement when doing so is the only way to develop permitted densities without disturbing the conservation lands described in Sections 4-7.2 and 4-7.3. Each of the following restrictions shall apply:
    1. Up to ten lots may share a common access easement.
    2. The lots shall be designed to ensure the health, safety, and welfare of future residents of the development in terms of access by service and emergency vehicles, pedestrian safety, and compliance with other applicable Sections of the zoning code.
    3. For common access easements longer than 150 feet that terminate in a dead-end, a vehicle turnaround shall be provided.
4-7 Conservation Lands
  1. Conservation Lands. Conservation Lands are the undisturbed areas of at least 50 percent of the tract to be set aside. Conservation lands are made up of Primary and Secondary Conservation areas. All lands identified as Primary Conservation areas shall be Conservation Lands. If the Primary Conservation area makes up less than 50 percent of the tract, the balance of the required Conservation Lands shall be made up of Secondary Conservation Areas.
  2. Primary Conservation Areas. The following shall be considered Primary Conservation areas and shall be included as Conservation Lands, unless the applicant demonstrates that this provision would be counter to the purposes of a Conservation Subdivision:
    1. The 100-year floodplain.
    2. All perennial and intermittent streams and associated floodways with a 75-foot corridor measured from the outer edge of the floodway.
    3. Contiguous slopes over 20 percent.
    4. Wetlands.
    5. Known habitat for rare, threatened, or endangered species.
    6. Cedar Glade Communities.
    7. Archaeological sites, cemeteries and burial grounds.
  3. Secondary Conservation Areas. Secondary Conservation areas shall be prioritized on the tract in terms of their highest to least suitability for inclusion in the Conservation Lands. The following shall be considered Secondary Conservation areas and shall be included in the Conservation Lands to meet at least minimum area percentage requirements for conservation lands:
    1. Existing healthy, native forests of a least one-acre contiguous area.
    2. Prime farmland soils and land in agricultural use.
    3. Designated historic and specimen trees.
    4. Other significant natural features and scenic viewsheds.
    5. Existing and planned trails that connect the tract to neighboring areas.
    6. Contiguous slopes between 15 and 20 percent.
    7. Significant historical and cultural sites.
  4. Additional Lands Set Aside. Land that is dedicated for use for a sanitary sewer disposal, whether for a public system or an individual sewage disposal system or other sewage disposal system approved by Metro Water Services, or land that is dedicated for conventional stormwater management devices, that require a disturbance to the land, shall be set aside for such purposes and not included as Conservation Lands.
4-8 Lot Arrangement
  1. Four Step Design Process for Conservation Subdivisions. All concept plans for Conservation Subdivisions shall include documentation of a four-step design process in determining the layout of proposed conservation lands, house sites, streets and lot lines as described below and illustrated in Figure 4-2.
  2. Step 1: Delineation of Conservation Lands
    1. The percentage and acreage of required Conservation Lands shall be calculated by the applicant and submitted as part of the concept plan. Road rights-of-way shall not be counted towards the required minimum open space.
    2. Lands to be included as Conservation lands shall be determined in the following manner:
      1. All Primary Conservation areas, unless the applicant demonstrates that this provision would be counter to the purposes of a Conservation Subdivision.
      2. If the Primary Conservation areas do not make up at least 50 percent of the tract, Secondary Conservation areas which shall be delineated to meet at least the minimum area percentage requirements. Secondary Conservations areas shall be chosen for inclusion based on the priorities determined in Section 4-7, the configuration of the tract, the tract's context to adjacent resource areas, and the applicant's subdivision objectives.
    3. Conservation Lands shall be delineated outside of individual development lots in a manner clearly indicating their boundaries as well as types of resources included within them.

      Figure 4-2: Four-Step Design Process for Conservation Subdivisions
  3. Step 2: Location of Building Areas. Potential building areas shall be tentatively located using the map delineating Conservation Lands, supplemented by existing conditions data required for concept plan approval. Building areas should generally be located not closer than 100 feet from Primary Conservation areas and 50 feet from Secondary Conservation areas, taking into consideration the potential negative impacts of residential development on such areas as well as the potential positive benefits of such locations to provide attractive views and visual settings for residences. Locating building areas on ridges, hilltops, along peripheral public roads or in other visually prominent areas should be minimized.
  4. Step 3: Alignment of Streets and Trails. After designating the building areas, a street plan shall be designed to provide vehicular access to each building area, complying with the standards in these Subdivision Regulations and bearing a logical relationship to the topography of the property. Impacts of the street plan on proposed Conservation Lands shall be minimized, particularly with respect to crossing environmentally sensitive areas such as wetlands, streams, and slopes exceeding 15 percent. Street connections shall minimize the number of cul-de-sacs and facilitate access to and from building areas in different parts of the property and adjoining properties.
  5. Step 4: Drawing in the Lot Lines. Upon completion of the preceding three steps, lot lines shall be drawn as required to delineate the boundaries of individual residential lots, using Section 17.12.xx of the Zoning Code to determine minimum lot sizes.
4-9 Requirements for Design and Improvement
  1. Standards for Conservation Subdivisions. In addition to the requirements contained in the General Requirements for all subdivisions, the following standards shall apply to Conservation Subdivisions.
  2. Relationship to Scenic Routes. A Conservation Subdivision fronting or encompassing a street designated on the Major Street Plan as a scenic arterial shall be subject to the following standards (See figure 4-3 for an example):
    1. Right-of-way shall be platted as noted in Section 3-10.5.
    2. Wherever practicable, lots shall not back onto the scenic easement.
    3. Access to the lots may be via a frontage road, shared driveways, rear alley access, or similar means to allow lots to front onto the scenic easement.

      Figure 4-3: Relationship to Scenic Routes
  3. Street Design in Conservation Subdivisions.
    1. The street network shall form a connected pattern.
    2. The street pattern shall be designed to respect and follow existing terrain as much as possible to minimize earthmoving and disturbance of the existing topography.
    3. Streets may take the form of a two way street, a pair of one-way streets on either side of a landscaped median or a one way loop street around a small neighborhood green.
    4. Streets may be designed using the appropriate street types contained in the Contextual Street Classification as defined in Section 7-2.
    5. Driveway crossings on streets built without curb and gutters shall meet the standards for driveway crossings contained in Volume 1 of the Stormwater Management Manual.
    6. Street connections shall be provided to existing or proposed through-streets or collectors adjacent to the subdivision, wherever practicable.
    7. Cul-de-sacs are generally prohibited and shall be permitted only where all other street design alternatives, such as loop streets or closes shown in Figure 4-4, are not feasible and one of the following two conditions exists:
      1. Where natural features such as wetlands or steep slopes exist or other primary or secondary conservation areas that are not desirable to remove.
      2. Where connection to an existing or planned street is blocked by an existing permanent structure, an existing or planned interstate, or a protected open space area.

        Figure 4-4: Alternatives to Cul-de-sacs.
    8. The street network shall be designed to:
      1. Preserve existing tree lines, hedgerows, and watercourses.
      2. Minimize alteration of natural, cultural, or historic features.
      3. Promote pedestrian movement.
      4. Secure the view to prominent natural vistas.
      5. Minimize crossing of Primary Conservation Areas.
  4. Requirements for Alleys. Alleys shall be strongly encouraged where practicable to reduce the need for curb cuts. The following standards shall apply to alleys in conservation subdivisions:
    1. Alleys, wherever practicable, shall connect with streets at their ends and dead-end alleys shall be avoided.
    2. Turnarounds shall be provided if a dead-end alley is longer than 150 feet.
    3. Alleys may contain turns and intersections with other alleys provided that service vehicles can be accommodated.
    4. Alleys shall serve as a utility corridor and wherever practicable, utilities shall be located to the rear of buildings.
    5. The right-of-way of the alley shall be a minimum width of 20 feet.
    6. Public alleys shall be approved by the Public Works Department.
    7. For all lots where the distance from the dwelling unit to the street via the alley may be greater than 150 feet, the alley shall serve as a fire lane as well as providing vehicular access to dwelling units.
  5. Supporting Agricultural Uses. The design of the Conservation Subdivision shall:
    1. Support continuing or proposed new agricultural uses on the tract and adjacent tracts by configuring lots in a manner that maximizes the usable area remaining for such agricultural uses
    2. Include appropriate separations between agricultural uses and residential structures to allow for the continued agricultural use.
    3. Minimize impacts to prime farmland soils and large tracts of land in agricultural use
    4. Avoid interference with normal agricultural practices
  6. Connecting Open Spaces and Access to Open Space. When locating open space the applicant shall:
    1. Connect proposed open space to any neighboring areas of open space or protected areas whenever possible.
    2. Develop a pathway system connecting open space areas accessible to neighborhood residents and connecting these areas to neighborhood streets and to planned or developed trails on adjacent tracts.
    3. Ensure the portion of open space designed to provide plant and animal habitat be kept as intact as possible and trails shall be designed to avoid fragmenting these areas.
    4. Every effort shall be made to ensure that Conservation Lands are contiguous and narrow or isolated fragments of Conservation Lands shall be avoided.
  7. Clearly Delineated Conservation Lands. There shall be a clear delineation through signage or other means between the individual development lots and Conservation Lands and the maintenance of the delineation shall be included in the Conservation Lands Management Plan required in Section 4-13.
  8. Areas of Common Sewage Disposal for Individual Sewage Disposal Systems. The location of all operating parts of the individual sewage disposal systems or other sewage disposal system approved by Metro Water Services, situated in lands held in common and any easements shall be shown on the final subdivision plat.
4-10 Homeowners Association
  1. Homeowners' Association Required. A homeowners' association shall be established and membership in the association shall be mandatory for all purchasers of homes in the development and their successors.
  2. Bylaws. The homeowners' association bylaws, guaranteeing continuing maintenance of the open space and other common facilities, and the declaration of covenants, conditions, and restrictions of the homeowners association shall be submitted for approval to the Executive Director as part of the information required for the development plan.
  3. Required Information. The homeowners' association bylaws or the declaration of covenants, conditions and restrictions of the homeowners association shall contain the following information:
    1. The legal description of the common land including any working agricultural uses as appropriate.
    2. A description of common facilities.
    3. The restrictions placed upon the use and enjoyment of the lands or facilities.
    4. Persons or entities entitled to enforce the restrictions.
    5. A mechanism to assess and enforce the common expenses for the land or facilities including upkeep and maintenance expenses, real estate taxes, and insurance premiums.
    6. A mechanism for resolving disputes among the owners or association members.
    7. The conditions and timing of the transfer of ownership and control of land and facilities to the association.
    8. Any other matter the developer deems appropriate.
4-11 Ownership of Conservation Lands
  1. Ownership Alternatives. Metro, an individual, a group of individuals, a nonprofit organization, a homeowners' association, a public body, or a combination of these entities may hold fee simple title to the Conservation Land. Any use of the Conservation Lands shall be in conformance with the Conservation Lands Management Plan.
  2. Homeowners' Association. Any land dedicated to a sewage disposal system, if the subdivision is served by an individual sewage disposal system, or other sewage disposal system approved by Metro Water Services, or for a conventional stormwater management device that requires a disturbance to the land shall be owned by the homeowners' association and shall be considered lands held in common but not considered Conservation Lands.
  3. Legal Instrument for Permanent Protection. All Conservation Lands shall be provided permanent protection through a conservation easement granted to a third party (party other than owner of fee simple). Use of the Conservation Lands shall be in conformance with the Conservation Lands Management Plan.
  4. Alternative to Conservation Easement. The Planning Commission may consider an alternative permanent protection measure that would provide equal or greater protection to the Conservation Lands as a conservation easement. Use of the Conservation Lands shall be in conformance with the Conservation Lands Management Plan.
4-12 Conservation Easement Holder
  1. Conservation Easement Holder Alternatives. The Conservation Easement on the Conservation Land shall be held by one of the following:
    1. A Nonprofit Organization. A nonprofit organization devoted to conservation and preservation may be designated as the holder of the Conservation Easement for the Conservation Land. The organization shall be acceptable to the Executive Director. The focus of the conservation and preservation activities of the nonprofit shall include one or more of the following:
      1. Historic sites.
      2. Archeological sites.
      3. Agricultural uses.
      4. Natural and hazard areas including:
        1. Perennial and intermittent streams and associated floodways.
        2. Floodplains.
        3. Steeply sloped land.
        4. Wetlands.
        5. Known habitat for rare, threatened, or endangered species.
        6. Cedar Glade Communities.
        7. Forested or meadowlands.
        8. Significant natural features and scenic viewsheds.
    2. Public Agency. A Public Agency involved in Conservation and Preservation may be designated as the holder of the Conservation Easement for the Conservation Land.
  2. Conservation Easement Holder in Place. Conservation easement holder, or alternative as provided in Section 4-11.4 shall be in place before building permits are issued.
4-13 Maintenance of Conservation Lands
  1. Conservation Lands Management Plan. In addition to the requirements of Section 2-5.1.g.2, a Conservation Lands Management Plan, approved by the Planning Commission shall be required that:
    1. Allocates responsibility and guidelines for the maintenance and operation of the Conservation Lands, lands held in common and any facilities, including provision for ongoing maintenance and for long-term capital improvements.
    2. Estimates the cost and staffing requirements needed for maintenance, operation, and insurance and outlines the means by which such funding shall be obtained or provided.
    3. Provides that any changes to the management plan be approved by the Planning Commission.
    4. Provides for enforcement of the management plan.
  2. Maintenance of Natural Features. Natural features shall be maintained in their natural condition. The cost and responsibility of maintaining Conservation Lands and any facilities located thereon shall be borne by the property owner(s) as described in Section 4-11. Any planting materials used shall follow the Urban Forestry "Recommended and Prohibited Tree and Shrub List" and the Parks Department "Landscaping with Native Plants" (Middle TN). Any modifications to the natural features shall be designed to ensure that the purpose of the Conservation Subdivision continuous to be met. Permitted modifications include:
    1. Reforestation.
    2. Woodland management.
    3. Pasture or cropland management.
    4. Buffer area landscaping.
    5. Stream bank protection.
    6. Wetlands management.
    7. Trails management.
  3. Tax Assessment of Conservation Lands. Once a legal instrument for permanent protection has been placed upon the Conservation Lands, the tax assessor shall be notified of the reduction in development rights in order to initiate reassessment of the conservation lands to reflect the more limited use.