119-11 Tier I Requirements
To the maximum extent possible, existing trees shall be retained. Trees of six-inch caliper or more may only be removed or destroyed as a result of a development, enlargement or site alteration, provided that:
(a) such trees are located in areas to be occupied by buildings, private roads, driveways, areas for required accessory parking, or within a distance of 15 feet of the exterior walls of such building, provided that it is not possible to avoid such removal by adjustments in the arrangement of such buildings, driveways or required parking areas;
(b) the continued presence of such tree would create special hazards or dangers to persons or property, which would not be possible or practical to eliminate by pruning;
(c) the continued presence of such tree would interfere with the growth or health of another tree of six-inch caliper or more designated for preservation and belonging to a species listed in Appendix B (Selection List for On-site Trees); or
(d) an authorization pursuant to Section 119-313 (Modification of landscaping, tree preservation and tree planting requirements) has been granted by the City Planning Commission approving the removal of such trees.
Any tree of six-inch caliper or more that cannot be preserved as a result of a proposed development, enlargement or site alteration shall be replaced pursuant to the provisions of Section 119-112 (Tier I tree planting requirements).
All developments, enlargements and site alterations on Tier I sites shall comply with the tree planting requirements set forth in this Section, whether or not existing trees are removed as a result of such development, enlargement or site alteration. However, the requirements set forth herein shall not apply to any enlargement of an existing building, provided that such enlargement does not increase the lot coverage of said building.
On-site trees, pre-existing or newly planted, shall be provided on the zoning lot at the rate of one tree for each 1,000 square feet of lot area, or portion thereof, or shall equal a total of 51 percent of all tree credits for trees originally on site, whichever is greater.
For any existing tree of at least six-inch caliper that is preserved, credit for one tree shall be given for the first six inches of caliper and, for each additional four inches of caliper, credit for an additional tree shall be given.
Single-trunk trees, newly planted to meet this requirement, shall be of at least three-inch caliper at the time of planting. Multiple-trunk trees and low-branching coniferous evergreens shall be at least 10 feet in height at the time of planting. On-site trees shall be of a species selected from Appendix B (Selection List for On-site Trees).
The following requirements must be met during construction:
(a) Construction fences shall be erected around all areas of no disturbance.
A tree protection plan is required to modify the area of no disturbance around trees proposed for preservation.
(b) The staging area shall be located in an area that would most minimize destruction of the natural features of the landscape. Such area shall be as close to the construction area on the zoning lot as practical, and shall be either on the flattest portion of the zoning lot or behind a containment wall where it will not erode any area of no disturbance or endanger any tree designated for preservation.
(c) Topsoil shall be used in the area to be revegetated as soon as construction is complete.
(d) Any exposed earth area shall have straw, jute matting or geotextiles placed on it within two days of exposure and be seeded with annual rye grass during construction.