1. Purpose. The RC Rural Conservation Development Overlay District is intended to require development design standards and techniques in sensitive environmental areas around Denison that preserve unique landforms and the character of land. The techniques of the RC district require that the natural landforms determine the design and character of new residential development in these sensitive areas. Areas of environmental sensitivity and potential application of the RC Overlay District may be established by the city’s comprehensive development plan.
2. Process. Subdivisions in an RC Overlay district generally follow the approval procedures outlined in the City’s Subdivision Ordinance, establishing the process for preliminary and final plat approval. Projects which do not require subdivision follow approval procedures appropriate to the specific project, including Special Use Permits, zoning amendments, site plan review, or other applicable measures. The requirements and standards included in this section are in addition to those established procedures.
3. Permitted Land Uses. Land uses permitted in an RC District are the same as those permitted in the underlying base district.
4. Permitted Density Yield. Developments in RC Overlay districts are permitted the same density on developable area as would be allowed to conventional residential development in the underlying zoning district. Yield in housing units (Y) is calculated by the formula:
where:
TA = Total parcel area
UA = Undevelopable areas, defined as the sum of wetlands designated by the National Wetlands Survey, Water of the United States, slopes exceeding 20%, floodways, and soils subject to slumping, as indicated on the medium intensity maps contained in the county soil survey published by the USDA Soil Conservation Service, is subtracted from the total parcel area.
.90 = an allowance for the typical percentage of land available after deducting the area of public streets and right-of-ways serving a low-density residential development.
SA = Minimum site area per unit required by the underlying zoning district.
5. Minimum Percentage of Open Space.
A. The minimum percentage of land that shall be designated as permanent open space, not to be further subdivided, and protected through a conservation easement held by the City of Denison, Crawford County, a Homeowners Association, or a recognized land trust or conservancy, shall be a minimum of 35% of the Net Developable Area, defined as .90(TA-UA)
B. The above areas shall generally be designated as undivided open space, to facilitate easement monitoring and enforcement, and to promote appropriate management by a single entity according to approved land management standards.
C. All undivided open space and any lot capable of further subdivision shall be restricted from further subdivision through a permanent conservation easement, in a form acceptable to the City and duly recorded in the Crawford County Register of Deeds Office.
D. The required open space may be used, without restriction, for underground drainage fields for individual or community septic systems. “Spray fields” for spray irrigation purposed in a “land treatment” sewage disposal system must receive prior, specific approval from the Planning Commission. “Mound” systems protruding above grade and aerated sewage treatment ponds shall be limited to no more than ten percent of the required minimum open space and must receive prior, specific approval from the Planning Commission.
E. Storm water management ponds or basins may be included as part of the minimum required open space, as may land within the rights-of-way for underground pipelines. However, land within the rights-of-way of high tension power lines shall not be included as comprising part of the minimum required open space.
6. Conservation Areas as Open Space.
A. The location of open space shall be consistent with the policies contained in the City of Denison’s Comprehensive Plan, and with the recommendations contained in this section and the following section (“Evaluation Criteria”).
B. Open space shall be comprised of two types of land; “Primary Conservation Areas” and “Secondary Conservation Areas.” All lands within both Primary and Secondary Conservation Areas shall be protected by a permanent conservation easement prohibiting future development, and setting other standards safeguarding the site’s special resources from negative changes.
(1) Primary Conservation Areas. This category consists of wetlands designated by the National Wetlands Survey, Water of the United States, slopes exceeding 20%, floodways, and soils subject to slumping, as indicated on the medium intensity maps contained in the county soil survey published by the USDA Natural Resources Conservation Service.
(2) Secondary Conservation Areas. Secondary Conservation Areas comprise at least 35 percent of the Net Developable Area and shall be designated and permanently protected. Full density credit shall be allowed for land in this category that would otherwise be buildable under local, state, and federal regulations, so that their development potential is not reduced by this designation. Such density credit may be applied to other unconstrained parts of the site. Secondary Conservation Areas are determined by specific project design and typically include all or some of the following kinds of resources:
a. A 100-foot deep greenway buffer along all waterbodies and watercourses, and a 50-foot greenway buffer alongside wetlands soils classified as “very poorly drained” in the medium intensity county soil survey of the USDA Natural Resources Conservation Service). These areas must be conserved as Secondary Conservation Areas but are considered as Developable Areas for the purpose of calculating yield.
b. 100-year floodplains.
c. Woodlands, individual specimen trees, or small stands of significant trees.
d. Aquifer recharge areas and areas with highly permeable (“excessively drained”) soil.
e. Significant wildlife habitat areas.
f. Class I and Class II farmlands.
g. Historic, archaeological or cultural features listed (or eligible to be listed) on the National Register of Historic Places or the Historic Resources Surveys of the Nebraska State Historical Society.
h. Slopes in excess of 15%.
i. Ridgelines and view corridors.
j. Land with soils that do not support residential development.
7. Location Standards for Open Space.
A. Access to Residential Lots. Undivided open space shall be directly accessible to the largest practicable number of lots within a conservation subdivision. To achieve this, the majority of house lots should abut undivided open space in order to provide direct views and access. Safe and convenient pedestrian access to the open space from all lots not adjoining the open space shall be provided (except in the case of farmland, or other resource areas vulnerable to trampling damage or human disturbance). Where the undivided open space is designated as separate, noncontiguous parcels, no parcel shall consist of less than three (3) acres in area nor have a length-to-width ratio in excess of 4:1, except such areas that are specifically designed as village greens, ballfields, upland buffers to wetlands, waterbodies or watercourses, or trail links.
B. Interconnection of Open Spaces. Protected open spaces in each new subdivision are encouraged to adjoin each other, ultimately forming an interconnected network of Primary and Secondary Conservation Areas across the county. The only elements of the network that would necessarily be open to the public are those lands that have been required to be dedicated for public use and typically configured in a linear fashion as an element of Denison’s long-range open space network through the Comprehensive Plan.
8. Special Processes for Conservation Developments. The review and approval process for subdivisions in the RC Overlay District is the same as that for conventional subdivisions, as set forth in the Subdivision Ordinance. Additional provisions and approval processes are set forth in this section.
A. Existing Features Plan.
(1) Plans analyzing each site’s special features are required for all proposed subdivisions. The Existing Features Plan shall include at a minimum (1) a contour map based at least upon topographical maps published by the U.S. Geological Survey; (2) the location of severely constraining elements such as steep slops (over 25%),wetlands, watercourses, intermittent streams and 100 year floodplains, and all rights-of-way and easements; (3) soil boundaries as shown on USDA Natural Resources Conservation Service medium- intensity maps; and (4) the location of significant features such as woodlands, treelines, open fields or meadows, scenic views into or out from property, watershed divides and drainage ways, fences or stone walls, rock outcrops, and existing structures, roads, tracks and trails.
(2) The Existing Features Plan shall identify both Primary Conservation Areas and Secondary Conservation Areas, as described in subsection 6 of this section. The Existing Features Plan shall form the basis for the Conceptual Preliminary Plan, which shall show the tentative location of houses, streets, lot lines, and greenway lands in new subdivisions, according to the four-step design process described in paragraph B below.
B. Conceptual Preliminary Plan. A sketch plan or a Conceptual Preliminary Plan shall be submitted for all proposed Rural Conservation subdivisions to the Zoning Administrator before submission of a formal preliminary plat application. A Conceptual Preliminary Plan presents a conceptual layout for greenway and open lands, land lot lines, and street alignments. Each Conceptual Preliminary Plan shall follow a four-step design process, as described below. Applicants shall be prepared to demonstrate to the Zoning Administrator that these four design steps were followed in the preparation of the plan.
(1) Step One: Designating the Open Space. During the first step, all potential conservation areas (both primary and secondary as defined above) are identified, using the Existing Features Plan.
(2) Step Two: Location of House Sites. House sites should generally be located not closer than 100 feet from Primary Conservation Areas, but may be situated within 50 feet of Secondary Conservation Areas, in order to enjoy views of the latter without negatively affecting the former.
(3) Step Three: Street and Lot Layout. The third step consists of aligning proposed streets to provide vehicular access to each house in the most reasonable and economical way. When lots and access streets are laid out, they shall be located in a way that avoids or at least minimizes adverse impacts on both the Primary and Secondary Conservation Areas. To the greatest extent practicable, wetland crossings and streets traversing existing slopes over 15% shall be strongly discouraged. Street connections shall generally be encouraged to minimize the number of new cul-de-sacs to be maintained and to facilitate easy access to and from homes in different parts of the property (and on adjoining parcels). Where cul-de-sacs are necessary, those serving six or fewer homes may be designed with “hammerheads” facilitating three-point turns.
(4) Step Four: Lot Lines. The fourth step is simply to draw in the lot line (where applicable). These are generally drawn midway between house locations and may include L-shaped “flag lots” meeting the city’s minimum standards for the same.
(5) Review and Comments. The Zoning Administrator and the Public Works Director shall return written comments on the Conceptual Preliminary Plan to the applicant within 30 days of submittal. These comments should recommend changes to be made prior to submittal of a Preliminary Plat application.
9. Ownership and Maintenance of Common Open Space. Developments in the RC Overlay District shall provide for ownership and maintenance of common open space. Common open space within a development shall be owned, administered, and maintained by any of the following methods, either individually or in combination, and subject to approval by the City.
A. Offer of Dedication. The City of Denison or Crawford County shall have the first and last offer of dedication of undivided open space in the event said land is to be conveyed. Dedication shall take the form of a fee simple ownership. The City or other public agency may, but shall not be required to accept undivided open space provided: (1) such land is accessible to the residents of the county; (2) there is no cost of acquisition other than any costs incidental to the transfer of ownership such as title insurance; and (3) the county agrees to and has access to maintain such lands. Alternatively, a public agency may accept an easement, subject to the above conditions.
B. Homeowners Association. The undivided open space and associated facilities may be held in common ownership by a homeowners’ association. The association shall be formed and operated under the following provisions:
(1) The developer shall provide a description of the association, including its bylaws and methods for maintaining the open space.
(2) The association shall be organized by the developer and shall be operated with financial assistance from the developer, before the sale of any lots within the development.
(3) Membership in the association is automatic (mandatory) for all purchasers of homes therein and their successors. The conditions and timing of transferring control of the association from developer to homeowners shall be identified.
(4) The association shall be responsible for maintenance of insurance and taxes on undivided open space, enforceable by liens placed by the county on the association. The association may place liens on the homes or house lots of its members who fail to pay their association dues in a timely manner. Such liens may require the imposition of penalty interest charges.
(5) The members of the association shall share equitably the costs of maintaining and developing such undivided open space. Shares shall be defined within the association bylaws.
(6) In the event of a proposed transfer, within the methods here permitted, of undivided open space land by the homeowners’ association, or of the assumption of maintenance of undivided open space land by a public agency, notice of such action shall be given to all property owners within the development.
(7) The homeowners’ association may lease open space lands to any other qualified person, or corporation, for operation and maintenance of open space lands.
C. Condominiums. The undivided open space and associated facilities may be controlled through the use of condominium agreements. Such agreements shall be in conformance with the state statute. All undivided open space land shall be held as a “common element.”
D. Transfer of Easements to a Private Conservation Organization. An owner may transfer easements to a private, nonprofit organization, among whose purposes it is to conserve open space and /or natural resources, provided that:
(1) The organization is acceptable to the City, and is a bona fide conservation organization with perpetual existence and legal non-profit status (example: 501c3 status);
(2) The conveyance contains appropriate provisions for proper reverter or retransfer in the event that the organization becomes unwilling or unable to continue carrying out its functions; and
(3) A maintenance agreement acceptable to the commission is entered into by the developer and the organization.
10. Maintenance Standards.
A. Financial Responsibility. The ultimate owner of the open space (typically a homeowners’ association) shall be responsible for raising all monies required for operations, maintenance, or physical improvements to the open space through annual dues, special assessments, etc. The homeowners’ association shall be authorized under its bylaws to place liens on the property of residents who fall delinquent in payment of such dues or assessments.
B. Maintenance Enforcement.
(1) In the event that the association or any successor organization shall, at any time after establishment of a development containing undivided open space, fail to maintain the undivided open space in reasonable order and condition in accordance with the development plan, the City may serve written notice upon the owner of record, setting forth the manner in which the owner of record has failed to maintain the undivided open space in reasonable condition.
(2) Failure to adequately maintain the undivided open space in reasonable order and condition constitutes a violation of this section.
(3) Should any bill or bills for maintenance of undivided open space by the City or County be unpaid, a late fee of fifteen percent shall be added to such bills and a lien shall be filed against the premises in the same manner as other municipal claims.
11. Evaluation Criteria. In evaluating the layout of lots and open space, the following criteria will be considered by the Planning Commission and City Council as indicating design appropriate to the site’s natural, historic, and cultural features, and meeting the purpose of this section:
A. Protection of floodplains, wetlands, and steep slopes from clearing, grading, filling, or construction except as may be approved for essential infrastructure or active or passive recreation amenities.
B. Preservation and maintenance of woodlands, existing fields, pastures, meadows, and orchards, and sufficient buffer areas to minimize conflicts between residential and agricultural uses.
C. Maintenance of buffers at least 100 feet in depth adjacent to wetlands and surface waters, including creeks, streams, springs, lakes and ponds.
D. Design around existing treelines between fields or meadows, and minimal impacts on large woodlands (greater than five acres), especially those containing many mature trees or a significant wildlife habitat.
E. Maintenance of scenic views.
F. Avoidance of new construction on prominent hilltops or ridges, by taking advantage of lower topographic features.
G. Protection of wildlife habitat areas of species listed as endangered, threatened, or of special concern by the U.S. Environmental Protection Agency.
H. Design around and preserves sites of historic, archaeological, or cultural value, including stone walls, barn foundations, cellar holes, earthworks, and burial grounds.
I. Protection of rural character and improves public safety and vehicular carrying capacity by avoiding development fronting directly onto existing public roads.
J. Landscaping of common areas if appropriate.
K. Provision of active or passive recreational areas in suitable locations that offer convenient access by residents and adequate screening from nearby house lots.
L. Inclusion of a pedestrian circulation system providing access between properties, activities, or special features within the neighborhood open space system. All roadside footpaths should connect with off-road trails.
M. Provision of open space that is reasonably contiguous, avoiding fragmented open spaces.