6.2.4 Conservation Subdivision

The conservation subdivision standards are established for the following purposes:

1. To provide flexibility of design in order to promote environmentally sensitive and efficient uses of the land;

2. To preserve in perpetuity unique or sensitive natural resources such as groundwater, floodplains, wetlands, streams, steep slopes, woodlands and wildlife habitat;

3. To preserve important historic and archaeological sites;

4. To permit clustering of houses and structures on less environmentally sensitive soils which will reduce the amount of infrastructure, including paved surfaces and utility easements, necessary for residential development;

5. To reduce erosion and sedimentation by minimizing land disturbance and removal of vegetation in residential development;

6. To promote interconnected greenways and corridors throughout the community;

7. To promote contiguous green space with adjacent jurisdictions;

8. To encourage interaction in the community by clustering houses and orienting them closer to the street, providing public gathering places and encouraging use of parks and community facilities as focal points in the neighborhood;

9. To promote construction of landscaped walking trails and bike paths conveniently located both within the subdivision and connected to neighboring communities, businesses and facilities to reduce reliance on automobiles;

10. To conserve scenic views from public roadways and reduce perceived density; and

11. To protect prime agricultural land and preserve farming as an economic activity.

1. This conservation subdivision option is available as a use by right subject to subdivision approval in accordance with Sec. 3.6, Subdivision Review; and in accordance with the standards set forth in paragraph 6.2.4H, Primary and Secondary Conservation Areas.

2. As required under Sec. 3.6, Subdivision Review, a conservation subdivision shall conform to the requirements of this Ordinance, including Article 8, Environmental Protection, and other development-related ordinances; except that the requirements of this section shall supersede any conflicting ordinance provisions.

3. In the County jurisdiction, spray irrigation for the treatment of wastewater within a conservation subdivision shall require a major special use permit under Sec. 3.9, Special Use Permit, unless the area to be irrigated is a primary conservation area that is farmland or agricultural land. This requirement shall also apply within the City jurisdiction unless the system has been approved by the State.

The tract of land to be subdivided may be held in single and separate ownership or in multiple ownership. If held in multiple ownership, however, the site shall be developed according to a single plan with common authority and common responsibility.

Maximum density in a conservation subdivision shall be determined by multiplying the gross area of the tract of land, including all areas typically excluded from density calculations in Article 8, Environmental Protection, by the maximum gross density for the site as defined in subsection 6.2.1A, Dimensional Standards.

Mass grading is allowed in conservation subdivisions that receive public water/sewer service or use community wastewater treatment facilities or package treatment plants. It is prohibited in all other conservation subdivisions.

Except for paragraph 7.2.5, Ownership and Management of Open Space, the requirements of Sec. 7.2, Open Space, do not apply to conservation subdivisions.

The amount of open space shall be 50% of total gross area as required under Sec. 6.2, Residential Rural (RR) Development Intensity, and shall be apportioned as set forth below in paragraph G, Primary and Secondary Conservation Areas and Other Open Space.

Open space shall be held in common ownership or dedicated to the public or a land trust or similar conservation-oriented non-profit organization rather than platted as part of individual private lots, and shall be subject to the requirements of paragraph 7.2.5, Ownership and Management of Open Space.

4. Notwithstanding the above requirements, area within required riparian buffers can be used to satisfy any open space requirement.

In addition to all subdivision application materials required in accordance with Sec. 3.6, Subdivision Review, the applicant shall submit a site analysis map. The complete site analysis map shall first be presented for discussion at the pre-application conference required under paragraph 3.2.2, Pre-Application Conference.

The purpose of the site analysis map is to ensure that the important site features have been adequately identified prior to the creation of the site design, and that the proposed open space will meet the requirements of this section. The site analysis map shall include the following features:

a. Property boundaries;

b. All streams, rivers, lakes, wetlands and other hydrologic features;

c. Topographic contours of no less than 10-foot intervals unless a more precise vertical scale is available;

d. All primary and secondary conservation areas labeled by type (see paragraph H. below);

e. General vegetation characteristics;

f. General soil types and areas suitable for installation of on-site wastewater treatment systems;

g. The planned location of protected open space;

h. Existing roads and structures; and

i. Potential connections with existing open space and trails.

At least 80% of the required open space in a conservation subdivision shall consist of primary conservation areas.

Commentary: Because 50% of the total gross area in a conservation subdivision must be open space under paragraph 6.2.1, Development Standards, 40% of the total gross area must be primary conservation areas.

The following are considered primary conservation areas and shall be included within the required open space in the order of preference listed below. Secondary conservation areas and other open space can be included only after primary conservation areas comprise 80% of required open space.

a. Special Flood Hazard Areas and Future Conditions Flood Hazard Areas;

b. Riparian buffers along all perennial and intermittent streams;

c. Wetlands protected by the Army Corps of Engineers or the North Carolina Department of Environmental Quality and any provided or required buffers;

d. Lakes, ponds, and other water bodies, excluding created stormwater management facilities;

e. Areas at least 5,000 contiguous square feet in size with any natural slopes greater than 25%;

f. Existing forests (meeting the standards in paragraph 8.3.1D, Preserved Tree Coverage, except any that conflict with the provisions of this section), at least one contiguous acre in size, in which healthy hardwood trees at least 10 inches in diameter at breast height comprise at least 50% of the area;

g. Wildlife corridors, wildlife habitats, and other sites identified in the Durham County Inventory of Important Natural Areas, Plants and Wildlife (Inventory) or adopted plans;

h. Greenways, rail trails, and other open space identified in adopted plans;

i. Historic sites or structures currently designated in, or eligible for, the National Register of Historic Places;

j. Sites identified in the Durham Architectural and Historic Inventory;

k. Sites identified in the Durham County Archaeological Inventory and other identified archeological sites, including cemeteries and burial grounds;

l. Sites at least five contiguous acres in size identified by the City, County, State, or federal government as farmland or agricultural land that is prime, unique, or of statewide or local importance; and

m. Viewsheds from designated federal and North Carolina Scenic Byways.

The following are considered secondary conservation areas and shall be included within the required open space in the order of preference listed below if additional space is still required after all primary conservation areas have been included:

a. Existing forests (meeting the standards in paragraph 8.3.1D, Preserved Tree Coverage, except any that conflict with the provisions of this section), at least 12,000 contiguous square feet in size, in which healthy hardwood trees at least 10 inches in diameter at breast height comprise at least 50% of the area;

b. Areas with any natural slope greater than 20%, unless identified as primary conservation areas;

c. Buffers in excess of Ordinance requirements around any primary conservation area;

d. Individual existing healthy trees greater than 18 inches in diameter at breast height; and

e. New or existing improved pedestrian trails that are not identified as primary conservation areas or located in other conservation areas and that do not negatively impact other conservation areas. Such trails can be located in utility easements only if all utilities in the easements are buried, and in such cases only the improved trails, and not the easements, shall be considered secondary conservation areas.

The following areas can be included within the required open space if additional space is still required after all primary and secondary conservation areas have been included:

a. Any land used for agricultural purposes that is not a primary conservation area;

b. Naturally vegetated areas, or areas re-vegetated to appear naturally vegetated, that are not primary or secondary conservation areas;

c. Playing fields surfaced with natural turf;

d. Golf courses identified by the City or County as "green" due to use of best management practices, excluding club houses, parking areas, and other impervious surfaces;

e. Stormwater management facilities engineered as bioretention areas or wetlands, including easements for such facilities, can comprise a maximum of 10% of required open space.