| 11.4 | Steep Slope Protection Standards | ||
| The primary objectives for slope protection standards are to minimize grading, land instability and the removal of vegetation in order to a) protect the quality of wetlands and water courses below the slope from increased sedimentation; b) protect steep slope plant and animal habitat from disturbance and development and c) preserve the aesthetic quality of the natural terrain. | |||
| 11.4.1 | Steep Slope Areas | ||
| Slope is the relationship of vertical rise to horizontal run, expressed as a percentage. Steep slope areas shall be defined as land areas that a) have a grade of 25 percent or more, b) have an area of 10,000 square feet or greater and c) are located within 200 feet of any floodway fringe or perennial stream or within 100 feet of an intermittent stream. Steep slope areas refer to natural grades and shall not include man-made grades. Slope calculations shall use the smallest contour interval for which maps are available. Steep slope areas shall be determined irrespective of tract boundaries. | |||
| Steep slope areas shall be clearly indicated on all site plans, development plans, preliminary plats, final plats, major special use permits and minor special use permits. When a property owner or developer believes that the presence or location of a steep slope area is different than what is shown on the appropriate topographic map, the Development Review Board shall have the authority to determine the location or presence of the moderate or steep slope area for purposes of meeting the requirements of Section 11.4, Steep Slope Protection Standards. | |||
| 11.4.2 | Steep Slope Development Limitations | ||
| Development and land disturbing activity on steep slope areas shall be conducted only in accordance with the following requirements. Compliance with these requirements shall be determined by the approving authority. | |||
| 1. | Development shall be designed and constructed in order to minimize disturbance to the natural landform as much as possible. Development shall demonstrate appropriate terrain-adaptive design and construction techniques. Extensive grading shall be avoided. An inability to design a particular development allowed by the underlying zone without significant disturbance to the natural landform indicates that the site should not accommodate the full amount of proposed development.. Alternate site design and construction measures are encouraged to mitigate the effects of development on steep slopes. Reconstructed slopes shall not exceed fifty (50) percent ("2H:1V"). Non-load bearing retaining walls shall be encouraged in order to reduce the amount of disturbance to the natural slope. | ||
| 2. | In order to accommodate building placement on steep slope areas, front and side yard setbacks on lots on the interior of the development may be reduced by up to 50 percent at the discretion of the Development Review Board. | ||
| 3. | Sedimentation and erosion control shall be provided during and after construction consistent with the requirements of the Durham County and City of Durham Sedimentation and Erosion Control Ordinance, Section 14-57 Design and Performance Standards, Subsection (b). | ||
| 4. | On any tract proposed for construction, no more than 15 percent of the steep slope area on the tract shall be graded. For purposes of this calculation, the land areas of individual steep slope areas on the tract shall be added together to establish the total steep slope area for the tract. | ||
| 5. | Development shall be designed and arranged in order to minimize the impact of street construction on steep slope areas. Proposed rights-of-way for major thoroughfares, minor thoroughfares and collector streets shall be exempt from the steep slope area grading limits of Section 11.4.2 (2). provided that the Development Review Board determines that proposed rights-of-way are designed and arranged in order to minimize the impact on steep slope areas. | ||
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