§ 5-87. Mandatory design and performance standards for land-disturbing activity.

No land-disturbing activity subject to the control of this division shall be undertaken except in accordance with the following mandatory standards:

(1)

Buffer zone.

a.

Unless otherwise provided, the width of a buffer zone is measured from the edge of the water to the nearest edge of the disturbed area, with the twenty-five (25) percent of the strip nearer the land-disturbing activity containing the natural or artificial means of confining visible siltation.

No land-disturbing activity during periods of construction or improvement to land shall be permitted in proximity to a lake or natural watercourse unless a buffer zone is provided along the margin of the watercourse of sufficient width to confine visible siltation within the twenty-five (25) percent of the buffer zone nearest the land-disturbing activity. Waters that have been classified as trout waters by the environmental management commission shall have an undisturbed buffer zone twenty-five (25) feet wide or of sufficient width to confine visible siltation within the twenty-five (25) percent of the buffer zone nearest the land-disturbing activity, whichever is greater. Provided, however, that the town may approve plans which include land-disturbing activity along trout waters when the duration of said disturbance would be temporary and the extent of said disturbance would be minimal. This subdivision shall 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.

b.

The twenty-five (25) foot minimum width for an undisturbed buffer zone adjacent to designated trout waters shall be measured horizontally from the top of the bank.

c.

Where a temporary and minimal disturbance is permitted as an exception by subsection 1. hereinabove, land-disturbing activities in the buffer zone adjacent to designated trout waters shall be limited to a maximum of ten (10) percent of the total length of the buffer zone within the tract to be distributed such that there is not more than one hundred (100) linear feet of disturbance in each one thousand (1000) linear feet of buffer zone. Larger areas may be disturbed with the written approval of the director of the division of land resources of the department of environment, health, and natural resources.

d.

No land-disturbing activity shall be undertaken within a buffer zone adjacent to designated trout waters that will cause adverse temperature fluctuations, as set forth in 15 NCAC 2B.0211 "Fresh Surface Water Classification and Standards", in these waters.

(2)

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 structures. In any event, slopes left exposed will, within thirty (30) working days of completion of any phase of grading, be planted or otherwise provided with ground cover, devices, or structures sufficient to restrain erosion.

(3)

Ground cover. Whenever land-disturbing activity is undertaken on a tract comprising more than twenty thousand (20,000) square feet, if more than twenty thousand (20,000) square feet are uncovered, the person conducting the land-disturbing activity shall install such sedimentation and erosion control devices and practices as are sufficient to retain the sediment generated by the land-disturbing activity within the boundaries of the tract during construction upon and development of said tract, and shall plant or otherwise provide a permanent ground cover sufficient to restrain erosion after completion of construction or development. Except as provided in subsection 5. hereinbelow, provisions for a ground cover sufficient to restrain erosion must be accomplished within thirty (30) working days or one hundred twenty (120) calendar days, whichever period is shorter, following completion of construction or development.

(4)

Design and performance of control measures.

a.

Except as provided in subsection 2. hereinbelow and in the standard for sediment ponds in the soil erosion and sediment control manual, erosion and sedimentation control measures, structures, and devices shall be so planned, designed, and constructed as to provide protection from accelerated erosion and sedimentation from the calculated maximum peak rates of runoff from the ten-year frequency storm. Runoff rates shall be calculated using the procedures in the USDA Soil Conservation Service's "National Engineering Field Manual for Conservation Practices", or other calculation procedures acceptable to the erosion control officer.

b.

In high quality water (HQW) zones the following design standards shall apply:

1.

Uncovered areas in HQW zones shall be limited at any time to a maximum total area of twenty (20) acres within the boundaries of the tract. Only the portion of the land-disturbing activity within the HQW zone shall be governed by this section. Larger areas may be uncovered within the boundaries of the tract with the written approval of the director of the division of land resources of the department of environment, health, and natural resources.

2.

Erosion and sedimentation control measures, structures, and devices within HQW zones shall be so planned, designed, and constructed to provide protection from the runoff of the twenty-five-year storm which produces the maximum peak rate of runoff. The peak rate of runoff shall be calculated according to procedures in the United States Department of Agriculture Soil Conservation Service's "National Engineering Field Manual for Conservation Practices" or according to procedures adopted by any other agency of this state or the United States or any generally recognized organization or association.

3.

Sediment ponds (also called "sediment basins") with HQW zones shall be designed and constructed such that the pond will have a settling efficiency of at least seventy (70) percent for the forty (40) micron (0.04 mm) size soil particle transported into the basin by the runoff of that two-year storm which produces the maximum peak rate of runoff. The peak rate of runoff shall be calculated according to procedures in the United States Department of Agriculture Soil Conservation Service's "National Engineering Field Manual for Conservation Practices" or according to procedures adopted by any other agency of this state or the United States or any generally recognized organization or association.

4.

Newly constructed open channels in HQW zones shall be designed and constructed with side slopes no steeper than two (2) horizontal to one vertical if a vegetative cover is used for stabilization unless soil conditions permit a steeper slope or where the slopes are stabilized by using mechanical devices, structural devices or other acceptable devices. In any event, the angle for side slopes shall be sufficient to restrain accelerated erosion.

5.

Ground cover sufficient to restrain erosion must be provided for any portion of a land-disturbing activity in a HQW zone within fifteen (15) working days or sixty (60) calendar days, whichever period is shorter, following completion of construction or development.

(5)

Prior plan approval. No person shall initiate any land-disturbing activity on a tract if more than twenty thousand (20,000) square feet are to be uncovered unless, thirty (30) or more days prior to initiating the activity, an erosion and sedimentation control plan for such activity is filed with, approved by, and a grading permit obtained from the county.

(Ord. No. 93-2-22/O-1, § 8)