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VII. TREE PROTECTION DURING CONSTRUCTION
A. GENERAL GOAL OF SAVING TREES
Mature trees that are saved during construction increase the value of the property, as well as the
surrounding neighborhood and the larger community. Trees, particularly mature trees have aesthetic
appeal, improve air quality, reduce noise and heat, sequester carbon and screen glare. They also
stabilize soil, aid natural flood control, create habitat for wildlife and provide privacy. For specific
legal requirements, see the Tree Bylaw, (Appendix I, Page 64) https://www.ecode360.com/10535335
To achieve the goal of saving trees, do the following in your design development:
1. Retain a Registered Surveyor The surveyor must show on the base plan all trees of six inch DBH or
greater, and the setback area. (See Figure 1, Page 7.)
2. Retain a Certified Arborist The arborist will assess tree health, certify hazardous trees for bylaw
exemption, and prepare and execute a required Tree Protection Plan to preserve trees in the setbacks
or Town right-of-way.
3. Design to Save Specimen Trees and Large Shade Trees Identify specimen trees and large shade trees,
especially those six inches or larger in diameter. Design the site plan to preserve these trees, using
them as a distinctive focus or framing feature to enhance the plan and buildings. Take care to allow
enough space around them to ensure their survival. (See Figure 12, Page 37.)
4. Transplant when Possible Specimen Trees and Large Shade Trees in the Way of Construction. If they
can be transplanted on site, incorporate them into the site design.
5. Remove Unsafe Trees Identify trees that are terminally diseased, damaged beyond repair or in danger
of falling. Remove them early in the development process to create a safer building site for construction
workers.
6. Submit Plan to the Tree Warden Once a plan is developed; submit it to the Lexington Tree Warden
for review. Discuss and come to an agreement as to which trees are to be preserved, transplanted,
protected or removed.
7. Submit Tree Protection Plan to the Tree Warden If existing trees in the setbacks or Town right-of-way
are not to be removed, submit a Tree Protection Plan prepared by a certified arborist to the Tree
Warden. Install fencing specified in the plan, complete any root pruning and other measures required
by the plan, and have a certified arborist submit confirmation of tree protection plan completion to
Tree Warden prior to beginning any ground disturbing activities, including demolition or tree removal.
8. Prune Only as Necessary Prune the trees to be saved only as needed to remove broken branches, to
enhance their natural form and to fit with the proposed buildings. Trees need as much foliage as
possible to help them survive the stress of construction. Follow pruning procedures outlined on the
Lexington Tree Management Manual, (See Figure 9, Page 32, Figure 10, Page 33, Figure 11, Page
34.)
9. Design for Foundations Substitute posts and pillars for footings and walls where proposed foundations
conflict with tree roots. (See Figure 14, Page 41.)
B. PROTECTION REQUIREMENTS FOR EXISTING TREES
1. Barrier Protection Protect all trees to be saved before demolition and land clearing begins. If possible
install barriers at the critical root zone, the outer edge of the area under the leaf canopy, or in a circle
with a radius of 1 foot per inch DBH . The fenced Tree Save Area may be modified to a location
specified by a certified arborist in a Tree Protection Plan and agreed on during an on-site visit by the
Tree Warden and/or a Tree Committee representative. Construct barriers of stable metal posts that are
not easily moved, spaced a maximum of eight (8) feet apart, and five (5) foot high chain link or welded
wire fencing. This protection will prohibit heavy equipment from compacting soil, damaging roots,
breaking branches and scarring the tree trunk. (See Figure 13, Page 39.)
2. Signage Post signs reading, “TREE SAVE AREA – PLEASE KEEP OUT”/ “AREA DE
AHORRO DE ARBOLES – ENTRADA PROHIBIDA POR FAVOR”, in both English and
Spanish on the fencing..
3. Weights under Tree Park vehicles, equipment, or stockpile earth, fill and other materials ONLY
OUTSIDE the Tree Save Area.
4. Chemical Damage Dispose of all debris properly (rubble, cement, asphalt, petroleum products,
herbicides, all chemicals) away from the tree root zone.
5. Leaf Mulch Allow fallen leaves from the trees within the root zone to remain on the ground as mulch.
If leaves are on the lawn, they can be raked up or mowed.
6. Flooding Provide proper drainage so that roots of trees are free of standing water.
7. Fasteners Use separate posts instead of trees for fastening signs, fences, electrical wires and pulley
stays.
8. Fires Lexington requires a permit for open burning as described on the Lexington Fire Department
web site at https://www.lexingtonma.gov Search “Departments”, “Fire Department”, “Burn Permits”
\[online cited 15 February 2019\].
9. Watering In the absence of rain, water trees once a week by running a hose in the Tree Save Area for
15 minutes or provide water using tree irrigation bags. Apply mulch to retain soil moisture.
10. Utility Lines Locate all new underground utility lines outside the critical root zone of trees to be saved.
If not possible, tunnel under roots as an alternative, or root prune to reduce the Tree Save Area prior
to excavation. (See Figure 14, Page 41.)
11. Trunk Protection: If the protective fencing cannot be installed to protect the tree trunk then trunk
protection should be installed. Loosely tie protective 2x4 lumber around the tree trunk with rope, do
not use wire. Attach the rope to the 2x4’s using staples. Do not drive fasteners into the tree. Height of
the lumber shall be from the tree base including root flare to the bottom of the first branch, typically
6-8’. The 2x4 lumber should be angled so the trunk flare and buttress roots are also protected. Closed
cell foam padding, one-quarter (¼) inch thick minimum, can be placed between the trunk and the
lumber for added protection.
12. Soil Protection: Avoid compaction of the soil by keeping foot and vehicle traffic and storing of
materials away from the root zone and outside the Tree Save Area. In cases where allowing access
through the tree save area is unavoidable either a minimum one-half (½) inch steel plate placed on
top of a two (2) inch minimum bed of mulch (e.g. wood chips) or a minimum of three-quarter (¾) inch
plywood over a four (4) inch bed of mulch may be used to bridge over the protected root zone in the
tree protection area.
13. Construction within Critical Root Zone: If it is decided that a building, road, walk, utility or other
feature must be built within part of this area, it may still be possible to save the tree. Extra care must
be given to the tree.
a. Use hand tools instead of machines whenever possible;
b. Water the tree in monitored amounts;
c. Tunnel instead of trench for utilities through tree root zones (See Figure 14, Page 41). This is the preferred
method for utility installation.
d. Root pruning by or under the supervision of a certified arborist must be done prior to excavation or
grade change any time work encroaches on the critical root zone.
i. Excavate using an air spade, hydro excavation or hand tools to expose roots.
ii. Cut roots cleanly, removing no more than 40% of roots
iii. Backfill and water immediately
iv. If hole must be left open past end of day, cover roots with wet burlap
v. Monitor tree health and supply adequate water and mulch.
e. Construct retaining walls to allow the original grade in the root zone to be maintained (See Figure
15, Page 42).
14. Grade Change Guidelines Do not lower the grade or add fill within the critical root zone. If a
grade change is needed within the critical root zone, root pruning is required before that grade
change is made. (See Figure 15, Page 42.)