Grading, irrigation and paving beneath trees to be retained shall be given special attention. Every reasonable effort shall be made to avoid creating conditions adverse to the tree's health.

    A.    Fencing at the dripline shall be installed prior to the start of any grading or construction activity. This requirement shall be noted on all relevant construction and grading plans.

    B.    The natural ground within the driplines of protected trees shall remain as undisturbed as possible.

    1.    No grade cuts whatsoever shall occur within six feet of the trunk of a tree to be retained, and no grade cuts shall occur within the dripline of such tree; except, that when recommended by a certified arborist, grade cuts not to exceed a maximum of one foot in depth may be permitted when not closer than six feet of the trunk and not exceeding one-third of the area of the dripline of the tree; provided, however, that higher standards may be applied by the approving body.

    2.    No fill whatsoever shall be placed within six feet of the trunk of a tree to be retained, and no fill shall be placed within the dripline of such tree; except, that when recommended by a certified arborist, up to one-third of the area of the dripline of such tree may be filled not exceeding a maximum depth of one foot, with no fill whatsoever placed within six feet of the trunk; provided, however, that higher standards may be applied by the approving body.

    3.    No mechanical trenching whatsoever shall be allowed within the dripline of a tree to be retained. If it is absolutely necessary to install underground utilities within the dripline of a tree, the trench shall be hand dug in the vicinity of major trees to prevent root cutting and mangling which may be caused by heavy equipment.

    a.    Major roots two inches or greater in diameter encountered within the tree's dripline in the course of excavation from beneath trees which are not to be removed shall not be cut and shall be kept moist and covered with earth as soon as possible.

    b.    Roots one inch to two inches in diameter which are severed shall be sawed clean two inches behind the damage and painted with latex base paint or pruning compound and covered with earth as soon as possible.

    c.    Support roots that are inside the dripline of the tree shall be protected.

    d.    Cross-section drawings of proposed grading may be required where trees are located adjacent to roadways, new slopes or critical areas. In addition, a dimension from the face of a tree to some critical point or line may be required.

    C.    Drainage changes shall be minimized within driplines of trees to be retained.

    D.    No irrigation system shall be installed within the dripline of a tree which may be detrimental to the preservation of the tree unless specifically authorized by the approving body or the director of public works.

    E.    Paving within the dripline of a tree to be retained should be stringently minimized, with no paving whatsoever within six feet of the trunk. When paving is absolutely necessary within the dripline, porous material should be used, and not cover more than one-third of the area of the dripline. (Ord. 455 § 2 (part), 1991)