9.4.5 Constructed Buffer
A. Plant Units
The plant units listed below shall be considered comparable, and therefore interchangeable, as set forth below.
1. The following plant unit alternatives shall be used, unless otherwise specified in this Article, to satisfy the project boundary buffer requirements:
a. Alternative 1: Mixed Evergreen
b. Alternative 2: Deciduous
c. Alternative 3: Evergreen
d. Alternative 4: Overhead Utility
e. Alternative 5: Intense
2. Alternative 2, Deciduous, shall not be permitted adjacent to residential districts or uses unless employed with a wall pursuant to paragraph 9.4.8, Walls, Berms and Fences in Buffers.
3. Alternative 4, Overhead Utility, shall be permitted only where overhead utilities would conflict with the drip-line of canopy trees.
4. All shrubs used to meet plant unit requirements shall be upright shrubs.
B. Rural and Suburban Tier
1. The buffer width and planting requirements in the table below shall be used to meet the opacity standards established in paragraph 9.4.3, Standards. Use of the interactive buffer model established is allowed pursuant to paragraph 9.4.7, Interactive Buffer Model, and where the slope of the buffer is at least 15%, in which case the requirements of paragraph 9.4.5D, Existing Slope Impacts, shall be applied.
|
Min. Width |
Alternative 1 Mixed Evergreen |
Alternative 2 Deciduous |
Alternative 3 Evergreen |
Alternative 4 Overhead Utility |
|
|---|---|---|---|---|---|
|
Plant Material Required Per 100 Linear Feet |
|||||
|
0.2 |
10 feet |
1 Deciduous Canopy Tree |
2 Deciduous Canopy Trees |
0 Deciduous Canopy Tree |
0 Deciduous Canopy Tree |
|
0 Evergreen Canopy Tree |
0 Evergreen Canopy Tree |
2 Evergreen Canopy Trees |
0 Evergreen Canopy Tree |
||
|
1 Deciduous Understory Tree |
2 Deciduous Understory Trees |
0 Deciduous Understory Tree |
3 Deciduous Understory Trees |
||
|
2 Evergreen Understory Trees |
0 Evergreen Understory Tree |
3 Evergreen Understory Trees |
2 Evergreen Understory Trees |
||
|
13 Shrubs |
12 Shrubs |
13 Shrubs |
10 Shrubs |
||
|
0.4 |
20 feet |
3 Deciduous Canopy Trees |
4 Deciduous Canopy Trees |
0 Deciduous Canopy Tree |
0 Deciduous Canopy Tree |
|
1 Evergreen Canopy Tree |
0 Evergreen Canopy Tree |
4 Evergreen Canopy Trees |
0 Evergreen Canopy Tree |
||
|
2 Deciduous Understory Trees |
6 Deciduous Understory Trees |
0 Deciduous Understory Tree |
7 Deciduous Understory Trees |
||
|
5 Evergreen Understory Trees |
0 Evergreen Understory Tree |
9 Evergreen Understory Trees |
5 Evergreen Understory Trees |
||
|
40 Shrubs |
38 Shrubs |
38 Shrubs |
30 Shrubs |
||
|
0.6 |
30 feet |
6 Deciduous Canopy Trees |
7 Deciduous Canopy Trees |
0 Deciduous Canopy Tree |
0 Deciduous Canopy Tree |
|
1 Evergreen Canopy Tree |
0 Evergreen Canopy Tree |
7 Evergreen Canopy Trees |
0 Evergreen Canopy Tree |
||
|
4 Deciduous Understory Trees |
10 Deciduous Understory Trees |
0 Deciduous Understory Tree |
12 Deciduous Understory Trees |
||
|
9 Evergreen Understory Trees |
0 Evergreen Understory Tree |
16 Evergreen Understory Trees |
9 Evergreen Understory Trees |
||
|
70 Shrubs |
67 Shrubs |
68 Shrubs |
53 Shrubs |
||
|
0.8 |
50 feet |
6 Deciduous Canopy Trees |
8 Deciduous Canopy Trees |
0 Deciduous Canopy Tree |
0 Deciduous Canopy Tree |
|
1 Evergreen Canopy Tree |
0 Evergreen Canopy Tree |
8 Evergreen Canopy Trees |
0 Evergreen Canopy Tree |
||
|
4 Deciduous Understory Trees |
11 Deciduous Understory Trees |
0 Deciduous Understory Tree |
13 Deciduous Understory Trees |
||
|
10 Evergreen Understory Trees |
0 Evergreen Understory Tree |
17 Evergreen Understory Trees |
10 Evergreen Understory Trees |
||
|
77 Shrubs |
73 Shrubs |
74 Shrubs |
58 Shrubs |
||
|
1.0 |
80 feet |
7 Deciduous Canopy Trees |
10 Deciduous Canopy Trees |
0 Deciduous Canopy Tree |
0 Deciduous Canopy Tree |
|
1 Evergreen Canopy Tree |
0 Evergreen Canopy Tree |
10 Evergreen Canopy Trees |
0 Evergreen Canopy Tree |
||
|
5 Deciduous Understory Trees |
13 Deciduous Understory Trees |
0 Deciduous Understory Tree |
16 Deciduous Understory Trees |
||
|
12 Evergreen Understory Trees |
0 Evergreen Understory Tree |
20 Evergreen Understory Trees |
12 Evergreen Understory Trees |
||
|
85 Shrubs |
80 Shrubs |
83 Shrubs |
65 Shrubs |
||
2. When proposed residential units adjoin an active agricultural use, the minimum buffer width shall be 50 feet, with a minimum opacity of 0.2.
3. Buffer widths can be reduced by up to 25% through the incorporation of a wall or berm pursuant to paragraph 9.4.8, Walls, Berms and Fences in Buffers. Application of this reduction in width shall provide a corresponding reduction in the number of required shrubs.
C. Urban, Compact Neighborhood, and Downtown Tiers
1. The buffer width and planting requirements in the table below shall be used to meet the opacity standards established in paragraph 9.4.3, Standards, for the Urban Tier and those areas of the Downtown and Compact Neighborhood Tiers that adjoin development in the Urban or Suburban Tiers and the opacity standards established in paragraph 9.4.1C for Design districts.
|
Min. Width |
Alt. 1 Mixed Evergreen |
Alt. 2 Deciduous |
Alt. 3 Evergreen |
Alt. 4 Overhead Utility |
Alt. 5 Intense |
|
|---|---|---|---|---|---|---|
|
Plant Material Required Per 100 Linear Feet Of Buffer |
||||||
|
0.2 |
10 feet |
1 Deciduous Canopy Tree |
1 Deciduous Canopy Tree |
0 Deciduous Canopy Tree |
0 Deciduous Canopy Tree |
|
|
1 Evergreen Canopy Tree |
0 Evergreen Canopy Tree |
1 Evergreen Canopy Tree |
0 Evergreen Canopy Tree |
|||
|
1 Deciduous Understory Tree |
1 Deciduous Understory Tree |
0 Deciduous Understory Tree |
2 Deciduous Understory Trees |
|||
|
1 Evergreen Understory Tree |
0 Evergreen Understory Tree |
2 Evergreen Understory Trees |
1 Evergreen Understory Tree |
|||
|
3 Shrubs |
4 Shrubs |
4 Shrubs |
1 Shrub |
|||
|
0.4 |
15 feet |
2 Deciduous Canopy Trees |
4 Deciduous Canopy Trees |
0 Deciduous Canopy Tree |
0 Deciduous Canopy Tree |
|
|
1 Evergreen Canopy Tree |
0 Evergreen Canopy Tree |
3 Evergreen Canopy Trees |
0 Evergreen Canopy Tree |
|||
|
2 Deciduous Understory Trees |
3 Deciduous Understory Trees |
0 Deciduous Understory Tree |
5 Deciduous Understory Trees |
|||
|
3 Evergreen Understory Trees |
0 Evergreen Understory Tree |
5 Evergreen Understory Trees |
3 Evergreen Understory Trees |
|||
|
9 Shrubs |
14 Shrubs |
12 Shrubs |
3 Shrubs |
|||
|
0.6 |
20 feet1 |
4 Deciduous Canopy Trees |
7 Deciduous Canopy Trees |
0 Deciduous Canopy Tree |
0 Deciduous Canopy Tree |
2 Deciduous Canopy Trees |
|
1 Evergreen Canopy Tree |
0 Evergreen Canopy Tree |
6 Evergreen Canopy Trees |
0 Evergreen Canopy Tree |
4 Evergreen Canopy Trees |
||
|
3 Deciduous Understory Trees |
5 Deciduous Understory Trees |
0 Deciduous Understory Tree |
9 Deciduous Understory Trees |
2 Deciduous Understory Trees |
||
|
5 Evergreen Understory Trees |
0 Evergreen Understory Tree |
9 Evergreen Understory Trees |
5 Evergreen Understory Trees |
0 Evergreen Understory Tree |
||
|
18 Shrubs |
27 Shrubs |
24 Shrubs |
5 Shrubs |
19 Shrubs |
||
|
6-Foot Wall 2 |
||||||
|
0.8 |
22.5 feet |
0 Deciduous Canopy Tree |
3 Deciduous Canopy Trees |
|||
|
0 Evergreen Canopy Tree |
5 Evergreen Canopy Trees |
|||||
|
13 Deciduous Understory Trees |
3 Deciduous Understory Trees |
|||||
|
7 Evergreen Understory Trees |
0 Evergreen Understory Tree |
|||||
|
7 Shrubs |
28 Shrubs |
|||||
|
6-Foot Wall 2 |
6-Foot Wall 2 |
|||||
|
1.0 |
37.5 feet |
0 Deciduous Canopy Tree |
4 Deciduous Canopy Trees |
|||
|
0 Evergreen Canopy Tree |
6 Evergreen Canopy Trees |
|||||
|
13 Deciduous Understory Trees |
4 Deciduous Understory Trees |
|||||
|
7 Evergreen Understory Trees |
0 Evergreen Understory Tree |
|||||
|
7 Shrubs |
31 Shrubs |
|||||
|
6-Foot Wall 2 |
6-Foot Wall 2 |
|||||
2A solid hedge composed of a minimum of 40 evergreen understory trees per 100 linear feet can be substituted for a 6-foot wall.
2. The interactive buffer model established pursuant to paragraph 9.4.7, Interactive Buffer Model, shall be permitted to calculate acceptable reductions in buffer width or variable mixes of plant units. The model can also be used when the slope of the buffer is at least 15%, as set forth in paragraph 9.4.5D, Existing Slope Impacts.
3. For projects within the CI District and Design Districts, an alternative to project boundary buffers shall be permitted with the following provisions:
a. A solid hedge composed of a minimum of 40 evergreen understory trees per 100 linear feet, with a minimum height of six feet at time of planting; or
b. A wall pursuant to paragraph 9.4.8, Walls, Berms and Fences in Buffers, is provided so long as any wall that is a structural part of a building may only be used if there is no glazing in the wall.
4. For projects within the Urban Tier, CI District, and Design Districts, no buffer shall be required for projects on lots less than 20,000 square feet, except for industrial uses, which shall provide buffers pursuant to Sec. 9.4, Project Boundary Buffers.
D. Existing Slope Impacts
Existing slopes shall be considered those that are naturally occurring and not created through the grading of the site.
Commentary: Proposed projects may require more than one type of buffer. For example, a project site might include a modest slope along the southern property line (requiring a flat land buffer) and a 20% hill on the northern property line (requiring an Upslope Buffer).
1. Buffers with at Least 15% Slope
a. General
(1) Buffer design changes depending on the degree of slope and whether the property being developed is up or down slope from the property being protected.
(2) On slopes of at least 15% but less than 25%, for each 100 feet of buffer section length, an upslope or downslope buffer shall be required.
(3) On slopes of least 25% for each 100 feet of buffer section length, a steep slope buffer shall be required.
(4) Sloped buffer areas less than 100 feet in length, as measured parallel to the property line, and with less than five feet of difference in elevation between the project site and the adjacent property shall be considered flat lands and be exempt from providing slope buffers.
b. Downslope Buffer
(1) Where the area containing the buffer slopes down from the adjacent property line toward the interior of the project at a slope of at least 15% but less than 25%, the buffer may be less effective because roof areas may be exposed (the adjacent property looks down onto the proposed site). In such cases, a steep slope buffer retaining the forest cover, or a standard project boundary buffer can be used buffer.
(2) If a constructed buffer is to be provided, 60% of the buffer width (starting at the property line) shall be graded to a slope of less than 15% with the adjacent land. The fill shall return to grade at a slope not to exceed 1:3 (33%). This may require a wider buffer to accommodate the fill. The interactive buffer model established pursuant to paragraph 9.4.7, Interactive Buffer Model, shall be used to determine whether the buffer achieves the required opacity.
c. Upslope Buffers
(1) Where the area containing the buffer slopes up from the adjacent property line toward the interior of the project site at a slope of at least 15% but less than 25%, the buffer may be more effective due to the masking potential of the slope. In such cases, a standard project boundary buffer, a steep slope buffer, or the interactive buffer model established pursuant to paragraph 9.4.7, Interactive Buffer Model can be utilized.
2. Steep Slope Buffer (Slope at least 25%)
a. Tree Covered Slopes
If a buffer area has a slope of at least 25% and tree coverage meeting the standards of paragraph 8.3.1D, Preserved Tree Coverage, exists on the site, the slope area shall be assumed to meet the requirements of a natural buffer with no healthy trees or shrubs removed and no grading or clearing permitted.
b. Slopes with Minimal Tree Coverage
If a buffer area has a slope of at least 25% but lacks the tree cover as specified above, then tree replacement pursuant to paragraph 8.3.1E, Replacement Tree Coverage, shall be required, except that:
(1) No trees greater than two inches caliper shall be planted; and
(2) A minimum of ten understory trees shall be provided per acre.
E. Buffer Width Modification
Buffer width shall normally be calculated as perpendicular to the property line, however, width modifications are allowed and shall be calculated based on the average width of the buffer per 100 feet or portion thereof.
1. In no case shall the minimum width of the buffer be less than one-half the required width.
2. The maximum width, for the purposes of installing required landscaping or receiving credit for existing vegetation, shall not be more than one and one-half times the required buffer width.