Appendix K. ARBORICULTURAL PRACTICES - PARKS
I.
Tree Protection
The contractor shall be responsible for any and all damage to retained trees. Unauthorized removal or damage to such trees shall be compensated as the assessed value of the tree prior to construction in accordance with the evaluation system.
Compensable damage as determined by the City shall be defined as major damage which may result in death or loss of vigor and may include toppling; broken or fracture main stem (trunk); wounds to the main stem which are deeper than 25 percent of the diameter or cover a surface area greater than one (1) square foot; breakage of more than 25 percent of the crown; encroachment of equipment, spoil, construction materials or toxic chemicals or exposure and damage to more than 25 percent of the root zone as measured by diameter of tree crown.
A.
All trees within the permanent and construction easements to be retained shall be protected during construction with temporary tree protection fencing.
B.
Tree protection fences shall be erected according to the Department of Environmental Protection Standards for Tree Protection.
C.
Tree protection fences shall be installed prior to the commencement of any site preparation work (clearing, grubbing or grading).
D.
Fences shall completely surround the tree or clusters of trees; will be located at the outermost limits of the tree branches (drip line); and will be maintained throughout the construction project in order to prevent the following:
1.
Soil compaction in the root zone area resulting from vehicular traffic or storage of equipment or materials.
2.
Root zone disturbances due to grade changes (greater than six (6) inches cut or fill) or trenching not reviewed and authorized by the City arborist.
3.
Wounds to exposed roots, trunk or limbs by mechanical equipment.
4.
Other activities detrimental to trees such as chemical storage, cement truck cleaning and fires.
E.
If in exceptional circumstances the fence is closer than four (4) feet to a tree trunk, protect the trunk with strapped-on planking to a height of eight (8) feet (or to the limits of lower branching) in addition to the reduced fencing provided.
F.
Where any of the above result in areas of unprotected root zones (under drip lines), those areas should be covered with four (4) inches of organic mulch to minimize soil compaction.
G.
All grading within protected root zone areas shall be done by hand or with small equipment to minimize root damage. Prior to grading, relocate protective fencing to two (2) feet behind the grade change area.
H.
Roots of a live tree (to be saved) exposed in a trench that are two (2) inches or larger in diameter shall be cut off square with a sharp medium tooth saw close to the trench wall and covered with pruning compound within two (2) hours after initial exposure. Backfill root areas with good quality top soil as soon as possible. If exposed root areas are not backfilled within two (2) days, cover them with organic material in a manner which reduces soil temperature and minimizes water loss due to evaporation. Prior to excavation or grade cutting within tree drip lines, make a clean cut between the disturbed and undisturbed root zones with a rock saw or similar equipment to minimize damage to remaining roots.
I.
Trees most heavily impacted by construction activities should be watered deeply once a week during periods of hot, dry weather. Tree crowns should be sprayed with water periodically to reduce dust accumulation on the leaves.
J.
Any trenching required for the installation of landscape irrigation shall be placed as far from existing tree trunks as possible.
K.
No landscape topsoil dressing greater than four (4) inches shall be permitted within the drip line of trees. No soil is permitted on the root flare of any tree.
L.
Pruning of trees over hanging easements to provide clearance for structures, vehicular traffic and equipment shall take place before construction begins and shall be implemented only after prior notice to the Parks and Recreation Department.
M.
All finished pruning must be done according to recognized, approved standards of the industry (References the National Arborist Association Pruning Standards for Shade Trees available on request from the City arborist).
Pruning shall be performed under the following guidelines:
1
All limbs or branches to be pruned shall be cut or severed cleanly with saw or shears to avoid any breakage. Cuts should be made as flush as possible to the branch that is to remain.
2.
Large limbs or branches should be removed in smaller sections in order to avoid falling damage to surrounding vegetation.
3.
All cut surfaces on pruned trees shall be immediately treated with an approved tree wound dressing.
II.
Treatment of Minor Wounds or Breakages
Small wounds or minor breakages to any tree to be protected less than those damages specified as "compensable damages" as may result from equipment moving or any other construction activity shall be treated according to the following procedures:
A.
Scrapes, gouges, debarking or any other minor wounds or abrasions to the main stem or major limbs shall be cleaned of loosened tissues as necessary with saw, shears or wood chisel to result in clean, even edges and shall be immediately treated with an approved tree wound dressing.
B.
For minor breakages or fractures to tree limbs or branches, the affected part shall be cleanly sawn or sheared several inches below the damaged area in order to result in a clean sever which shall be immediately treated with an approved tree wound dressing.
C.
Exposed, broken or scraped root structures shall be cleaned as above and immediately treated with approved tree wound dressing. Exposed roots should be recovered with sandy loam soil or equivalent to original depth as soon as construction proceeds past the affected area.
D.
Breakages or fractures to the main stem (trunk), major wounds or limb breakages or toppling of any trees to be protected or preserved during construction shall require immediate consultation with the City to determine correct treatment procedures.