A major purpose of this article is to protect all designated trees which are not removed and to allow approved construction to occur. The following procedures shall apply to all types of construction projects which involve development around designated trees. The following procedures are deemed appropriate in the situations noted; however, unique circumstances may allow modifications if deemed necessary by the administrative official.
(1) Prohibited activities.
The following activities shall be prohibited within the limits of the drip line of any designated tree that is subject to the requirements of this article:
(A) Materials storage.
No materials intended for use in construction or waste materials accumulated due to excavation or demolition shall be placed within three feet (3') of the trunk of any designated tree.
(B) Equipment cleaning and disposal of liquids.
No equipment may be cleaned or other liquids deposited within the limits of the drip line of a designated tree. This includes, but is not limited to, paint, oil, solvents, asphalt, concrete, mortar or other materials.
(C) Attachments to trees.
No signs, wires or other attachments, other than those of a protective nature, shall be attached to any tree.
(D) Vehicular or equipment traffic.
No vehicular and construction equipment traffic or parking is allowed within three feet (3') of the trunk of a designated tree.
(2) Mulching and pruning.
The procedures listed below shall be followed prior to construction:
(A) Protective mulching.
All designated trees shall have a minimum of four inches (4") of mulch placed from the base of the tree to the designated tree’s drip line to reduce soil compaction.
(B) Pruning.
If a low-hanging limb is broken during the course of construction, the remaining portion of the limb may be cut. The limb shall be cut either flush to the trunk on or at the next joint of the limb. The wound shall then be sealed with pruning paint. In no instance shall pruning involve a portion of the trunk or thirty percent (30%) of the entire canopy without the administrative official’s prior approval.
(3) Improvements within critical root zone.
Design constraints often dictate that designated trees slated for preservation have some encroachment on their critical root zone. The following are the minimum design criteria allowed within the critical root zone of a designated tree. Development exceeding the criteria would put the designated tree at risk, and therefore it will no longer be considered a preserved designated tree. In such case, replacement trees shall also be required.
(A) Grade changes.
In the event that grade changes must be made around a designated tree or group of designated trees, the following shall be implemented in order to maintain oxygen and water exchange within the designated tree’s critical root zone:
(i) A minimum of seventy-five percent (75%) of the critical root zone must be preserved at natural grade with natural ground cover or landscaping for the tree to be considered a preserved designated tree.
(ii) No cut or fill greater than two inches (2") shall be located closer to the tree trunk than one-half (1/2) of the radius of the critical root zone radius distance.
(iii) Decrease grade: Provide retaining walls outside the drip line to mitigate cuts.
(B) Boring of utilities.
The administrative official may permit boring under designated trees in certain circumstances. The minimum length of the bore shall be the width of the tree’s canopy and shall be at a minimum depth of twenty-four inches (24").
(C) Trenching.
Irrigation systems shall be designed to avoid trenching across the critical root zone of any designated tree. Bore or air spade may be an acceptable alternative.
(D) Paving.
A maximum of twenty-five percent (25%) of the critical root zone of a designated tree may be covered with impervious paving. The pavement and the cut and fill for the pavement is to not exceed one-half (1/2) of the critical root zone radius distance.
(4) Other requirements.
(A) Tree protection fences shall be installed prior to the commencement of any site preparation work (clearing, grubbing or grading).
(B) Fences shall be located at least three feet (3') from the base of the trunk of the designated tree to prevent:
(i) Soil compaction in the critical root zone resulting from vehicular traffic or storage of equipment or materials.
(ii) Critical root zone disturbances due to grade changes greater than two inches (2") cut or fill, or boring which was not authorized by the administrative official.
(iii) Wounds to the trunk, limbs or exposed roots by mechanical equipment.
(iv) Other activities detrimental to trees such as chemical storage, cement truck cleaning, and fires.
Fence material shall consist of 4-foot-high orange safety fence which is staked in a manner to support the fencing during the duration of construction. |
(C) All grading within critical root zones of designated trees shall be performed by hand or small equipment to minimize damage.
(D) Trees most heavily impacted by construction activities should be watered deeply once a week during periods of hot and dry weather. Tree crowns should be sprayed with water periodically to reduce dust accumulation on the leaves.
(E) Trenching for landscape irrigation shall be located as far from the existing tree drip line as possible and performed by hand or air spade.
(F) Pruning to provide clearance for structures, vehicular traffic and equipment shall take place before construction begins.
(1996 Code, sec. 12.406)
