Unified Development Ordinance, 31st Supplement, May 2024

CHAPTER 9. ​NATURAL RESOURCE PROTECTION | Article 9.5. Watershed Protection Areas

C. Design and Performance Standards and Guidelines 1. Copies of design and performance standards which are contained in Guidelines for Land-Disturbing Activities will be published by the City and placed on file in the Office of the City Clerk and the Engineering Services Director. 2. All erosion control plans, erosion control measures, ground covers, maintenance and calculations must be in accordance with the applicable Guidelines for Land-Disturbing Activities and State of North Carolina Erosion and Sediment Control Planning and Design Manual; in the event of any conflict, the more stringent regulation applies. D. Buffer Zones 1. Buffer Zones Generally a. No land-disturbing activity during periods of construction or improvement to land are allowed in proximity to a lake or natural watercourse unless a buffer zone is provided along the watercourse to confine visible siltation within 25% of the buffer zone nearest the land disturbing activity. b. Unless otherwise provided, the width of a buffer zone is measured from the edge of the watercourse to the nearest edge of the disturbed area. 2. Buffer Zone Exceptions This section does not apply to a land-disturbing activity in connection with the construction of facilities to be located on, over or under a lake or natural watercourse. No land-disturbing activity, except as permitted in Sec. 9.2.3.B. and Sec. 9.2.3.C. or Article 9.5. Watershed Protection Areas , shall take place: a. Within any watercourse buffer area unless it conforms to the requirements of Sec. 9.2.3.B. and Sec. 9.2.3.C. and the provisions of this Article; and

structures. In any event, slopes left exposed shall be provided with ground cover, devices or structures sufficient to restrain erosion. For all areas of moderate or steep slopes, temporary ground cover shall be provided if the slope has not been disturbed for a period of 14 days. F. Ground Cover 1. Whenever a land-disturbing activity occurs, the person undertaking the activity shall install such ground cover, devices or structures sufficient to restrain erosion and retain sediment within the boundaries of the tract at all times. 2. Any portion of a site upon which further land-disturbing activity is not being undertaken shall be provided with ground cover sufficient to restrain erosion within 14 calendar days of temporarily or permanently suspending the land disturbing activity. Permanent ground cover shall be installed within 14 calendar days following completion of construction or development. G. Downstream Protection of Discharge Points and Receiving Watercourses 1. Permanent Protection Any area of a land-disturbing activity and all receiving watercourses or discharge point must be permanently protected from accelerated erosion caused by increased velocity of stormwater runoff resulting from a land disturbing activity. 2. Post Construction Velocity For any land-disturbing activity, the post construction velocity of the 10-year storm runoff in the receiving water-course to the discharge point does not exceed the greater of: a. The velocity of the 10-year storm runoff in the receiving watercourse prior to a development; b. The velocity specified according to the following table for a discharge point into a receiving watercourse with bare soil or rock bed or banks; or Maximum Permissible Velocities Material (F.P.S.) (M.P.S.)

b. Within any high-quality water zone unless it conforms to the requirements of Article 9.5. Watershed Protection Areas and the provisions of this Article.

E. Graded Slopes and Fills The angle for graded slopes and fills shall be no greater than the angle which can be retained by vegetative cover or other adequate erosion control devices or

9 – 47 Published May 2024

Part 10: Unified Development Ordinance City of Raleigh, North Carolina

Supp. No. 31