Duluth UDC § 716

American National Standards Institute (ANSI) and International Society of Arboriculture (ISA) Best Management Practices (BMPs) for tree conservation, protection, establishment, pruning, and maintenance are hereby established and shall be the minimum standards required. All activities associated with protected trees shall conform to these technical standards. In addition, all tree conservation, protection, establishment, pruning, and maintenance shall conform to applicable American National Standard for Arboricultural Operations – Safety Requirements Z133.1 safety standards published by the American National Standards Institute, and as officially revised and amended from time to time. a. Professional assistance. Any person or firm subject to the requirements of this chapter is encouraged to seek professional assistance from a registered forester or certified arborist. A list of consulting foresters and arborists is available from the Georgia Forestry Commission, and certified arborists can be located online on the International Society of Arboriculture’s website. b. Arboricultural (tree) services. Any person or firm subject to the requirements of this chapter is encouraged to hire only qualified, established businesses to perform arboricultural services, to require references for similar work before hiring, and to require adequate insurance for property damage, personal liability, vehicles, and workers compensation. The hiring of arboricultural businesses and tree services that employ certified arborists who can supervise the requested work is recommended. c. Administrative waiver of technical standards. The Director of Planning and Development may waive any technical standard in Section 716 to best meet the purpose and intent of this chapter. When granted, waivers shall be recorded in writing on the application for the Buffer and Landscape Plan or other permanent record. d. Tree conservation standards; forested areas. The conservation of forested areas shall meet the minimum criteria below. 1) Each area shall be at least 2,500 square feet. 2) At least 50 percent of the area shall be contiguous 3) Each area shall be a minimum of 20 feet wide in any one dimension. 4) Each area shall include the tree protection zones of all trees, and the trees shall be protected according to the tree protection standards set forth in Section 716(g). 5) Areas shall remain in a natural, undisturbed condition. 6) Turf is not permitted. 7) Clearing of underbrush is not permitted, except for the removal of invasive species. 8) No new tree maintenance shall be required, except for that necessary to maintain a healthy stand of trees. 9) Mowing is not permitted. 10) Areas dominated by kudzu, Chinese privet or any other invasive species will not be eligible for tree canopy cover credit. 11) Tree removal without prior approval is not permitted, except for hazard trees. e. Tree conservation standards; individual trees. The conservation of individual healthy trees or groups of healthy trees shall meet the minimum criteria below. 1) Each tree must meet the definition of a conservable tree. 2) The tree protection zone of each tree shall be conserved and the tree protected according to the tree protection standards set forth in Section 716(g). 3) Each tree shall be mulched in accordance with the mulching standards set forth in Section 716 (g.9.i). f. Forest regeneration area establishment standards. Forest regeneration shall meet the minimum criteria below. 1) Each area shall be at least 2,500 square feet. 202 | P a g e Article Seven. Landscaping, Buffers, and Tree Protection 2) Soils shall be aerated to a depth of eight inches. 3) Soils shall have a minimum of five percent organic matter. 4) Wood chips less than three months old shall not be used to provide organic matter. 5) Soils shall have a pH between 5.8 and 7.0. 6) Trees shall be planted at a rate of at least 245 trees per acre. 7) All species planted shall be native to the Piedmont region of Georgia. 8) A minimum of 15 percent of the trees planted shall be large canopy trees that are at least 2 inches caliper and at least five feet tall at the time of planting and shall be evenly distributed throughout the forest regeneration area. 9) A minimum of 30 percent of the trees planted shall be medium canopy trees at least .5 inch caliper and at least three feet tall at the time of planting and shall be evenly distributed throughout the forest regeneration area. 10) The remaining 55 percent of the trees planted shall be a mixture of small, medium, and large canopy trees and shall be at least one-year old seedlings, at least 1.5 feet tall at the time of planting, and shall be evenly distributed throughout the forest regeneration area. 11) No more than 15 percent of any one species shall be planted. 12) Only native grasses and shrubs may be planted within the forest regeneration area, except that non-native vegetation approved for soil sedimentation and erosion control may be used. 13) The area shall remain free from English ivy, Chinese privet, Japanese honeysuckle, kudzu, and other invasive or non-native plants. 14) Turf is not permitted. 15) Mowing is not permitted. 16) Tree removal without prior approval is not permitted, except for hazard trees. 17) At least 200 healthy trees per acre must be maintained within the forest regeneration area or planting to meet this minimum shall be required. 18) Forest regeneration shall be located within any available common areas, if possible, before permitted on individual lots. g. Tree protection standards. City of Duluth trees or trees on private property conserved and planted to meet tree canopy cover requirements shall be actively protected during development, based on ANSI and ISA BMP’s, and passively throughout their life. 1) Prohibited activities. The following activities and conditions, and any other activities and conditions harmful to a tree’s roots, trunk or crown, within the tree protection zone are prohibited: i. Vehicle or equipment traffic, parking, or storage. ii. Materials or supplies storage. iii. Placement of temporary or permanent structures. iv. Equipment maintenance or washout. v. Wounding of trunk. vi. Wounding or breakage of scaffold limbs or branches greater than six inches in diameter. vii. Topping or other improper pruning, such as stub cuts or flush cuts. viii. Fires; excessive heat from equipment exhaust pipes. 2) Limited activities. The following activities and conditions within the tree protection zone are limited to one side of the tree in the outer ½ of the critical root zone, but in no case closer than 2.5 feet to the trunk of a planted tree and ten feet to the trunk of a conserved tree: i. Site or lot clearing or grubbing ii. Soil excavation. iii. Soil cuts. iv. Soil fill. 203 | P a g e Article Seven. Landscaping, Buffers, and Tree Protection v. Grading. vi. Trenching. vii. Tilling. viii. Edging. ix. Soil compaction. x. Top dressing with soil greater than two inches in depth. xi. Paving. 3) Active tree protection standards. Active tree protection shall meet the following minimum criteria: i. Tree protection fencing shall be installed prior to any land development or land disturbance activity around a tree at the location of the tree protection zone and shall remain in place until construction activities end or a certificate of occupancy is issued, whichever is later. ii. Tree protection fencing shall be at least four feet high, and made of the following: 1. A minimum four-foot (4’) barrier, constructed in a post and rail configuration. A 2-inch x 4-inch post and a double 1-inch x 4-inch rail; or, 2. Four-foot orange polyethylene laminar safety fencing; or, 3. Six-foot chain link fencing. iii. Activities described in Section 716 (g.1) shall be prohibited within the tree protection zone. iv. Low hanging limbs that may be damaged by equipment traffic or other construction activities shall be pruned prior to the commencement of any land development/land disturbance activity; all pruning shall be in accordance with the pruning standards set forth in Section 716.7. v. When equipment movement is such that damage to tree trunks is possible, then tree trunks shall be wrapped vertically with one layer of two-inch by four-inch lumber spaced a maximum of 12-inches apart and covered with corrugated cardboard secured with strapping. The wrapping shall remain on throughout the period of potential damage. 4) Active tree protection area sign standards. Prior to any land development or land disturbance activity and after tree protection fencing is installed around any conserved trees or tree conservation area, tree protection area signs shall be installed. Signs shall be installed along the perimeter of all tree protection zones at least every 50 feet and shall include, at a minimum, the following text: Tree Protection Area, Entry Prohibited, No Construction Activity, Materials or Equipment Storage, Equipment Washout, or Vehicle Traffic Allowed”. The sign shall be written in both English and Spanish. The sign shall be fabricated out of a sturdy material, shall be at least 18 inches wide by 24 inches high, and shall be placed on a sturdy post with the bottom of the sign at a minimum height of 30 inches above the ground. The sign must always remain present during construction. 5) Passive tree protection standards. Passive tree protection shall be required throughout the life of a protected tree and shall require, at a minimum, the avoidance of all prohibited activities described in Section 716(g.1) within the tree protection zone. 6) Tree establishment standards. Tree establishment involves a series of steps that includes site selection, species selection, quality tree selection, site preparation, tree planting, and new tree maintenance. Tree establishment standards, based on ANSI standards, shall be as set forth in subsections (i) through (vii) below. i. Site selection standards. Trees shall be placed such that they have adequate space to grow unobstructed to maturity. Minimum distances, at the time of planting as 204 | P a g e Article Seven. Landscaping, Buffers, and Tree Protection measured from the tree trunk, to structures and infrastructure shall be required as listed in Table 7-C. In addition, the following standards apply. 1. Trees shall not be planted directly over property boundary lines or corners. 2. In no case shall a planting site be less than three feet wide in any one direction. ii. Species selection standards. Species planted to satisfy the requirements of this chapter shall be selected from the City of Duluth Tree Species List, and shall conform to the following standards: 1. Species shall be selected that are tolerant of the growing conditions existing on the site, including growing space, sunlight, soil moisture, temperature, and soil volume. 2. No more than 50 percent of any one species shall be planted on a lot, except in forest regeneration areas where no more than 15 percent of any one species shall be planted. 3. For street trees, where no obstructions to growth exist, large canopy trees shall be planted; where obstructions to growth exist for large canopy trees, medium canopy trees shall be planted; where obstructions to growth exist for medium canopy trees, small canopy trees shall be planted. iii. Tree size and quality standards. Trees planted to satisfy the requirements of this chapter shall meet minimum quality standards as established in the ANSI Z60.1 American Standard for Nursery Stock and published by the American Horticulture Industry Association, as officially revised and amended from time to time. Trees shall also conform to the following standards to be eligible for tree canopy cover credit: 1. Trees shall be a minimum of two inches in caliper for deciduous trees, a minimum of eight feet in height for evergreen trees, and a minimum of one inch caliper per trunk for multi-trunk trees at the time of planting. 2. Trees outside the forest regeneration areas may be container grown or balled and burlapped. 3. Trees within forest regeneration areas may be bare root, container grown, or balled and burlapped. 4. Trees with forked stems and included bark shall not be counted for tree canopy cover credit. 5. Trees that require staking to stand upright shall not be counted for tree canopy cover credit. iv. Site preparation standards. The soil around a planted tree shall meet the following standards: 1. The soil within the open soil surface area shall be well aerated to a depth of eight inches, except that in tree planting islands surrounded by pavement it shall be aerated to a depth of 18 inches. 2. The soil shall contain at least five percent organic matter. 3. Soil pH shall be within a range of 5.8 to 7.0. 4. An approved chamber system of structural soil mix containing 80 percent rock aggregate, 15 percent mineral soil, and a sticking agent may be used within parking lots and other paved areas to increase the rooting volume available to trees. 5. Permeable or porous pavements may be used within a parking lot or other paved area, in which case the open soil surface area required may be reduced by up to 20 percent. 205 | P a g e Article Seven. Landscaping, Buffers, and Tree Protection v. Tree planting standards for container grown or balled and burlapped trees. The following standards shall apply to container grown and ballad and burlapped trees: 1. In undisturbed soils and prepared soils the planting hole shall be at least two times as wide and no deeper than the root ball of the tree, shall have sides sloping inward from the top, and the bottom shall be firm soil. 2. In compacted soils, the planting hole shall be at least three times as wide and no deeper than the root ball of the tree, shall have sides sloping inward toward the bottom, and shall have firm soil on the bottom. 3. The tree shall be planted no deeper than it was growing in the container or field and the trunk flare shall be visible above the ground. 4. All strapping, webbing, twine, strings, and other such material shall be removed from the root ball. 5. The burlap and wire basket, if present, shall be removed to a minimum depth of 12 inches and to a greater extent if possible. 6. In no case shall any burlap be located above the soil surface. 7. Tree staking is not required, but if installed it shall be removed no later than one year after planting. vi. Tree planting standards for bare root saplings and seedlings. The following standards shall apply to all bare root saplings and seedlings: 1. The roots of saplings and seedlings shall remain moist at all times prior to planting. 2. A planting hole shall be dug of sufficient depth to accommodate the root system of the tree without bending or creating a j-shaped root. 3. Trees shall be planted no deeper than they were growing in the field. 4. The soil shall be massaged around the roots after planting, and measures, such as watering in, should be taken to eliminate air pockets. vii. New tree maintenance standards. For newly planted balled and burlapped or container grown trees that are planted to satisfy the requirements of this chapter, except for those planted in forest regeneration areas, the property owner shall comply with the following maintenance standards for the first three years after planting: 1. Trees shall be mulched immediately after planting in accordance with the mulching standards set forth in Section 716.8. 2. When natural rainfall is less than one inch per week, trees shall be provided with the equivalent of one inch of water per week after planting and throughout the growing season and throughout the open soil surface area. 3. Trees shall be pruned immediately after planting to remove dead, broken, diseased, dying, or rubbing branches. 4. Tree pruning shall be done as necessary to remove dead branches, train tree structure, and maintain clearance over walkways and vehicles in accordance with the tree pruning standards set forth in Section 715.7. 5. Tree staking materials shall be removed within one year after planting. 7) Tree Pruning Standards. Protected trees shall be pruned in accordance with the American National Standard for Tree Care Operations A300 published by the American National Standards Institute and Best Management Practices published by the International Society of Arboriculture, as officially revised and amended from time to time. Tree owners and their agents are encouraged to hire businesses that employ certified arborists who can supervise the pruning 206 | P a g e Article Seven. Landscaping, Buffers, and Tree Protection work on site and ensure that proper pruning is being done. In addition, the following standards shall apply to protected trees: i. Pruning activities shall not disturb nesting, rare, or endangered wildlife to the greatest extent possible. ii. Co-dominant stems less than four inches in diameter at the fork shall be subordinated or removed and one main stem shall remain. iii. Pruning shall be done such that a tree’s natural form is maintained to the greatest extent possible. iv. Tree topping or heading is not permitted. v. Reasons for which tree pruning is not permitted include, but are not limited to: 1. Sign installation, clearance, or visibility, excluding traffic, directional, warning, or information signs owned by any public or semipublic agency. 2. Clearance for temporary or permanent equipment traffic or storage, the erection of temporary structures, or materials storage with the tree protection zone. 8) Tree maintenance standards. In addition to pruning, tree maintenance includes mulching, fertilization, cabling and bracing, and lightning protection. When required for protected trees as set forth herein, these activities shall be based on ANSI A300 Standards and done in accordance with the standards set forth below. i. Mulching standards. Individual planted trees, individual conserved trees, and groups of ten or less conserved trees shall be mulched in accordance with the following standards. For conserved groups of more than ten trees, forested areas, and forested buffers, the addition of mulch is not required; however, the ground surface and natural leaf litter within these areas shall remain present and undisturbed. 1. Mulch shall be composed of organic materials only and may include, but is not limited to, pine straw, leaves, wood chips aged at least three months, compost, and pine bark. 2. Grass clippings, plastic sheeting, and rocks or gravel shall not be used as mulch and shall not be applied within the tree protection zone. 3. For all trees the critical root zone shall be mulched out from the trunk at least one-third the distance to the outer edge of the critical root zone, except that no mulch ring shall have a radius less than 2.5 feet or shall be required to be greater than ten feet. 4. Mulch shall be three to four inches in depth and shall be spread in an even layer from six inches out from the trunk to outer extent of the mulched area. 5. Mulch is not allowed closer than six inches to the tree trunk. 6. Mulch shall be applied at least annually, preferably in the late winter or early spring. ii. Fertilization standards. Fertilization is not required for protected trees. However, if protected trees are fertilized, they shall be fertilized in accordance with the American National Standard for Tree Care Operations A300 (Part 2), published by the American National Standards Institute, and as officially revised and amended from time to time. iii. Tree support systems standards. Any tree support system placed in protected trees shall be designed, installed, and maintained in accordance with the American National Standards for Tree Care Operations ANSI A300 (Part 3), published by the American National Standards Institute, and as officially revised and emended from time to time. iv. Lightning protection systems standards. Any lightning protection systems placed in protected trees shall be designed, installed, and maintained in accordance with the 207 | P a g e Article Seven. Landscaping, Buffers, and Tree Protection American National Standard for Tree Care Operations ANSI A300 (Part 4), published by the American National Standards Institute, and as officially revised and amended from time to time. 9) Tree removal standards. The removal of protected trees shall be done in accordance with the standards set forth below. i. Tree removal shall not disturb nesting, rare, or endangered wildlife to the greatest extent possible, and removal shall be delayed until nesting wildlife is safely removed. ii. Tree removal shall be approved if a tree meets one or more of the following conditions: 1. Dead. 2. Unhealthy condition. 3. Dieback of 50 percent or greater of the crown. 4. Insect infestation or disease condition for which treatment is impractical, causing tree decline, and with a high probability of spreading to other trees. 5. Trunk wounds greater than one-third the circumference of the trunk. 6. Trunk cavity greater than two-thirds the diameter of trunk at the point of cavity. 7. Structural defects in scaffold limbs, where defect correction through pruning will result in removal of 50 percent or greater of the tree’s crown. 8. Litter originating from the tree that creates an unsafe condition or poses a hazard to public health, safety, and welfare. 9. Unresolvable conflict with infrastructure that is creating an unsafe condition or poses a hazard to public health, safety, and welfare. iii. Reasons for which tree removal is not permitted include, but are not limited to: 1. Sign installation, clearance, or visibility, excluding traffic, directional warning, or information signs owned by any public or semipublic agency. 2. Unwanted production of leaves, fruit, or other organic litter that does not create an unsafe condition or that is not a hazard to public health, safety and welfare. iv. Stump grinding standards. After removal, stumps of all trees shall be ground to a depth of 12 inches, and the resulting woody debris mixed with an equal part of soil. The surface of the ground in the area of the stump shall be level with the surrounding ground after grinding and incorporation of soil. 208 | P a g e Article Seven. Landscaping, Buffers, and Tree Protection