Tree Protection Plan for Adjacent Park Trees
An arborist's assessment and protection plan for trees in Burnside Watkiss Park adjacent to the development site.
Michael Gye Urban Forestry Ltd.
Consulting Arborists
Trees & Development • Hazard Assessment • Appraisals
July 12, 2016
Daryoush Firouzli Architecture Inc 6377 Icarus Dr Nanaimo BC V9V 1N4
To whom it may concern.
Subject : 1950 Watkiss Way, Victoria: Tree Protection Plan for Adjacent Park Trees
Assignment
Write a tree protection plan for the subject site with recommendations for minimizing and mitigating construction impacts to 7 adjacent trees in Burnside Watkiss Park.
Understanding construction damage
To understand the significance of construction impact it is necessary to be able to picture the area of a tree's root system. The average tree:
- has a horizontal root spread that is 2.5 - 3.0 times greater than the branch spread,
- has most (>60%) of it's roots outside of the drip line¹,
- has most (>95%) roots in the top metre of soil
- has most fine, or smallest diameter roots in the top 0.15 m (6 inches) of soil.
Trenching around trees for foundations or the installation of utilities can be very disruptive to root systems particularly when done within the dripline of the tree. Not only is the soil disturbed, but roots may be severed and exposed to the air resulting in possible additional injury to root tissues. Current recommendations for trenching along one side of a tree are to protect a circle about the trunk whose radius is 15 times the trunk diameter.
Other forms of construction damage:
- Soil compaction by trucks and heavy equipment is extremely damaging to tree roots.
- Soil pollution from spills of fuel, solvents, paints, lime, cement,
- Blasting damage. Fumes from burning explosives are extremely toxic to tree roots.
- Mechanical damage to tree trunks and root crowns by excavating equipment.
- Grade changes cause severe damage to trees. Fills bury and suffocate roots, cuts destroy roots.
¹ Drip line: The perimeter of the ground area covered by the tree's branch canopy
Introduction
On July 10, I attended a site meeting with Daryoush Firouzli, Architect and my assistant Darryl Clark. We identified, tagged, measured and assessed the condition of the 7 subject trees. I documented the field information needed to complete the report. Included in the report are;
- A tree inventory.
- A two page site drawing detailing my recommendations for the project contractor to follow.
- A diagram for the treatment of cut edges.
- A sketch for the tree protection fencing design.
Recommendations
Remove Douglas firs #195 and #199 Too much of each tree's Critical Root Zone (CRZ) will be removed in the excavation for the building foundation for these trees to survive with a safe useful life expectancy. In my opinion they will likely go into decline, and subsequently become hazardous before dying. View Royal may want to plant replacement trees on a 2 to 1 basis. I suggest Garry Oak as the replacement species for its tolerance to drought and flooding. It may also tolerate global warming better than Douglas fir.
Retain the remaining trees and mitigate construction damage as follows:
- Arborist to supervise all excavation in tree root zones (please phone the arborist at 250-361-8303 the day before he is needed on site).
- Contractor to cut all roots cleanly back to excavation edge as directed by arborist.
- Mulch retained trees and cover excavation edge with filter cloth (See Treatment Of Cut Edge And Root Curtain Installation below)
- Contractor to KEEP TREATED AREAS MOIST until the trenches are backfilled.
- The blasting contractor to be briefed by the arborist before drilling commences. Unloaded sheer line holes may be required between the tree's CRZ and explosive loaded holes. Only dynamite to be used next to or inside a CRZ (ANFO is highly toxic to tree roots and may not be used).
Tree Protection Fencing Fall Douglas firs #195 and #199 (and remove the dead stem on Garry oak #194) before installing the tree protection fencing. ROUT THE DOUGLAS FIR STUMPS BELOW GROUND – do not excavate the roots as this will damage the root systems of the adjacent trees.
A red dashed line on the accompanying site plan denotes tree protection fencing that needs to be installed for the protection critical root zones of the retained trees. The fencing installation must be inspected by the arborist before heavy construction equipment is allowed on site. Once installed, no one may enter a tree protection area or move the tree protection fencing without the arborist's permission.
- Arborist supervision The arborist must be on site to supervise and repair any root damage when excavating in any tree root area. Please call 250-361-8303 to give the arborist 24 hours' notice when he is needed on site.
If these tree protection measures and those noted on the site plan are implemented properly, construction impact on the retained park trees will be kept to a minimum and the trees should survive with a reasonable and safe useful life expectancy.
Yours truly,
Michael Gye Consulting Arborist For Michael Gye Urban Forestry Ltd 10539 McDonald Park Rd Sidney BC V8L 3J2 250-654-0550 250-361-8303 c mgye@shaw.ca
Arborist's Disclosure Statement
Arborists are tree specialists who use their education, knowledge, training and experience to examine trees, recommend measures to enhance the beauty and health of trees, and attempt to reduce the risk of living near trees. Clients may choose to accept or disregard the recommendations of the arborist, or to seek additional advice.
Arborist cannot detect every condition that could possibly lead to the structural failure of a tree. Trees are living organisms that fail in ways we do not fully understand. Conditions are often hidden within trees and below ground. Arborists cannot guarantee that a tree will be healthy or safe under all circumstances, or for a specified period of time. Likewise, remedial treatments, like any medicine, cannot be guaranteed.
Treatment, pruning and removal of trees may involve considerations beyond the scope of the arborist's services such as property boundaries, property ownership, site lines, disputes between neighbours, and other issues. Arborists cannot take such considerations into account unless complete and accurate information is disclosed to the arborist. An arborist should then be expected to reasonably rely upon the completeness and accuracy of the information provided.
Trees can be managed, but they cannot be controlled. To live near trees is to accept some degree of risk. The only way to eliminate all risk associated with trees, is to eliminate all trees.
Assumptions and Limiting Conditions
- Any legal description provided to the consultant is assumed to be correct. Any titles and ownerships to any property are assumed to be good and marketable. No responsibility is assumed for matters legal in character, nor is any opinion rendered as to the quality of any title. Any and all existing liens and encumbrances have been disregarded, and any and all property is appraised/evaluated as though free and clear, under responsible ownership, and competent management.
- It is assumed that any property is not in violation of any applicable codes, ordinances, statutes, or other governmental regulations.
- Care has been taken to obtain all information from reliable sources. All data has been verified insofar as possible; however, the consultant can neither guarantee nor be responsible for the accuracy of information provided by others.
- The consultant shall not be required to give testimony or attend court by reason of this report unless subsequent contractual arrangements are made.
- Loss or alteration of any part of this report invalidates the entire report.
- Possession of this report or a copy thereof does not imply right of publication or use for any purpose by any other than the person to whom it is addressed, without the prior expressed written consent of the consultant.
- Neither all nor any part of the contents of this report, nor copy thereof, shall be used for any purpose by anyone but the person to whom it is addressed, without the prior written consent of the consultant; nor shall it be conveyed by anyone, including the client, to the public through advertising, public relations, news, sales or other media, without the prior written or verbal consent of the consultant: particularly as to value conclusions, identity of the consultant, or any reference to any professional society or institute, or to any initialled designation conferred upon the consultant stated in his qualifications.
- This report and any values expressed herein represent the opinion of the consultant and the consultant's fee is in no way contingent upon the reporting of a specified value, a stipulated result, the occurrence of a subsequent event, nor upon any finding to be reported.
- Sketches, diagrams, graphs, and photographs in this report, being intended as visual aids, are not necessarily to scale and should not be construed as engineering or architectural reports or surveys.
- Unless expressed otherwise: 1) information contained in this report covers only those items that were examined and reflect the condition of those items at the time of inspection; and 2) the inspection is limited to visual examination of accessible components without dissection, excavation, or probing unless otherwise noted. There is no warranty or guarantee, expressed or implied, that problems or deficiencies of the plants or property in question may not arise in the future.
Tree Protection Plan Inventory
| Tree # | Species | DBH Inches | DBH (cm) | CRZR (m) | Condition | Retain Y/N | Remarks |
|---|---|---|---|---|---|---|---|
| 193 | Garry oak | 30 | 4.6 | Good | |||
| 194 | Garry oak | 32/30 | 4.8 | Fair/Dead | ?/no | 2 codominant stems - the smaller one is dead | |
| 195 | Douglas fir | 75 | 11.0 | Fair | |||
| 196 | Garry oak | 65 | 9.8 | Fair | |||
| 197 | Garry oak | 30 | 4.6 | Good | |||
| 198 | Douglas fir | 47 | 7.1 | Good | Leaning away from proposed development | ||
| 199 | Douglas fir | 52 | 7.7 | Good |
NOTE:
- DBH = DIAMETER at breast height
- CRZR = Critical Root Zone RADIUS (not diameter)
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