A. Retention. In the required perimeter landscaping area, applicants shall retain all significant trees. A significant tree means a healthy evergreen tree, six inches or more in diameter measured four feet above grade, or a healthy deciduous tree four inches or more in diameter measured four feet above grade. Alders and cottonwoods are excluded from this definition. If the grade level adjoining a tree to be retained is to be altered to a degree that would endanger the viability of a tree or trees, then the applicant shall construct a dry rock wall or rock well around the tree. The diameter of this wall or well must be capable of protecting the tree.

Areas devoted to driveways, curb cuts, and sight distance requirements, utilities and storm drainage facilities may be exempted from this requirement. Significant trees may also be exempted from this requirement if it is determined by the planning director based on satisfactory evidence pursuant to report prepared by a consulting arborist certified by the International Society of Arboriculture. The report submitted to the city shall demonstrate the significant tree is:

If additional significant trees are to be removed, the applicant shall seek approval of an “alternative landscape plan” from the planning director under ACC 18.50.080.

B. Encroachment into Dripline. No construction activities shall take place within the dripline of a tree to be retained without extra precautions as recommended by a certified arborist. The applicant may install impervious or compactable surface within the area defined by the dripline when a qualified arborist determines that such activities will not endanger the tree or trees. (See the definition of “dripline” in ACC 18.04.318.)

C. Tree Protection. All significant trees that are to be retained must be protected during construction by installation of a protective barricade or fence. This will require preliminary identification of the proposed area of disturbance for staff inspection and approval, then installation of a protective barricade or fence before major excavation with heavy equipment begins. (Ord. 6387 § 1, 2011.)