§ 26-223. Design criteria.

Water quality buffers shall be applied to community waters as stated in this section.

(1)

Streams. Water quality buffers shall be applied in the following manner to streams that are identified as community waters:

a.

A water quality buffer having a minimum width of 50 feet shall be provided along each side of a stream, as measured perpendicular from the top-of-bank of the active channel. For those streams that do not have a defined top-of-bank, the buffer shall be measured perpendicular from the centerline of the stream.

1.

The inner zone of the water quality buffer shall have a minimum width of 25 feet, measured perpendicular from the top-of-bank of the active channel and extending landward. For those streams that do not have a defined top-of-bank, the buffer shall be measured perpendicular from the centerline of the stream.

2.

The inner zone shall remain undisturbed in accordance with the policies set forth in the county stormwater management manual, as amended.

3.

The vegetative target for the inner zone is mature, moderately dense forest (i.e., trees) with woody shrubs and understory vegetation. Where forest vegetation has the potential to impact traffic safety or limit access, areas immediately surrounding approved stream crossings and utility access areas that are located in the inner zone may be vegetated with dense grasses.

4.

The outer zone of the water quality buffer shall be measured from the edge of the inner zone and shall extend the perpendicular distance required to obtain a total minimum buffer width of 50 feet, when combined with the width in the inner zone.

5.

The minimum vegetative target for the outer zone is mowed, dense grasses that cover the entire zone.

6.

The outer zone can be disturbed and graded, but must be revegetated in accordance with the policies set forth in the county stormwater management manual, as amended.

b.

The width of water quality buffers located on streams may be modified by averaging as set forth herein, and in accordance with policies stated in the county stormwater management manual, as amended, provided that the following conditions are met:

1.

The average width of the averaged buffer within the boundaries of the property to be developed must be at least 50 feet; and

2.

The width of the buffer shall not be less than 25 feet at any location, except where stream crossings have been approved by the director.

3.

Those areas of the buffer having a minimum width of 25 feet (or less at approved stream crossings) can comprise no more than 50 percent of the buffer length.

c.

Buffer averaging is required for water quality buffers that have stream crossings.

d.

Buffer width averaging is prohibited for any portion of developments that have (or will have) the land uses listed below.

1.

Slope protection areas, as identified by the Metropolitan Planning Commission, and areas that have slopes greater than 15 percent, that are located within 50 feet of the stream to be buffered;

2.

Developments or facilities that include on-site sewage disposal and treatment system drainfields (i.e., septic systems), raised septic systems, subsurface discharges from a wastewater treatment plant, or land application of biosolids or animal waste;

3.

Landfills (demolition landfills, permitted landfills, close-in-place landfills);

4.

Junkyards;

5.

Commercial or industrial facilities that store and/or service motor vehicles;

6.

Commercial greenhouses or landscape supply facilities;

7.

Developments or facilities that have commercial or public pools;

8.

Agricultural facilities, farms, feedlots, and confined animal feed operations;

9.

Animal care facilities, kennels, and commercial/business developments or facilities that provide short-term or long-term care of animals; and

10.

Other land uses deemed by the Director to have the potential to generate higher than normal pollutant loadings.

(2)

Ponds and lakes.

a.

Water quality buffers shall be applied in the following manner to ponds and lakes that are identified as community waters:

1.

For ponds and lakes that are directly connected to other community waters, a minimum buffer of 25 feet shall be provided around the perimeter of ponds and lakes. The buffer shall be measured perpendicular from the topographic contour that defines the normal pool elevation.

2.

The minimum vegetative target for the pond or lake buffer is mowed, dense grasses that cover the entire zone.

3.

The pond or lake buffer can be disturbed and graded but must be revegetated in accordance with the policies set forth in the county stormwater management manual, as amended.

b.

Water quality buffers shall not be required around the perimeter of hydraulically disconnected ponds, or ponds that are newly designed and constructed for the purposes of stormwater quality treatment.

(c)

Wetlands.

a.

Water quality buffers shall be applied in the following manner to wetlands that are identified as community waters:

1.

A minimum buffer width of 25 feet shall be provided around the perimeter of a wetland, as measured from the outermost edge of the wetland as determined by USACE, NRCS, TDEC, or other qualified professional.

2.

The vegetative target for the wetland buffer is undisturbed, mature, moderately dense forest (i.e., trees) with woody shrubs and understory vegetation.

3.

The wetland buffer shall remain undisturbed in accordance with the policies set forth in the county stormwater management manual, as amended.

b.

Water quality buffers are not required for wetlands designed and constructed for the purposes of stormwater quality treatment.

(4)

Steep slopes. Where slopes greater than 15 percent, or where slope protection areas as identified by the Metropolitan Planning Commission, are located within 50 feet of the community water, one of the two following conditions shall apply:

a.

The buffer width in the steep slope areas shall be adjusted to include an additional 25 feet, giving a total buffer width of 75 feet; or

b.

The buffer in steep slope areas shall have a minimum width of 50 feet and shall consist of one-zone, comprised of undisturbed, forested vegetation, as described in subsection (1)a.3.

(Ord. No. O-07-12-101, § 2(§ 6.3), 1-28-08)