Helmcken/Burnside – Tree Preservation Plan

Summary of Tree Resource

105 trees were inventoried on the subject properties, municipal frontages and neighbours’ properties that have the potential to be impacted by the proposed development. The trees inventoried are comprised of mixture of native and ornamental species and vary in health from Poor to Good (see attached Tree resource spreadsheet). The best opportunity for tree retention given the proposed building scheme will be around the perimeter of the subject property along with trees on neighbouring properties and trees on municipal frontages.

Potential Impacts on Trees to be Retained and Mitigation Measures

Barrier fencing

The areas surrounding the trees to be retained should be isolated from the construction activity by erecting protective barrier fencing. Where possible, the fencing should be erected at the perimeter of the critical root zones. The barrier fencing must be a minimum of 4 feet in height, of solid frame construction that is attached to wooden or metal posts. A solid board or rail must run between the posts at the top and the bottom of the fencing. This solid frame can then be covered with plywood, or flexible snow fencing. The fencing must be erected prior to the start of any construction activity on site (i.e. demolition, excavation, construction), and remain in place through completion of the project. Signs should be posted around the protection zone to declare it off limits to all construction related activity. The project arborist must be consulted before this fencing is removed or moved for any purpose.

Demolition of the Existing Houses

We anticipate that the demolition of the existing buildings on the properties will using the existing driveway as access. Trees to be retained near the existing driveways on the municipal frontages will have to be protected during the demolition process to mitigate any potential impacts.

Underground Parking excavation

The excavation for the portions of the underground parking that encroach into the critical root zones of trees to be retained must be supervised by the project arborist. To minimize the extent of the excavation, it will likely be necessary to use shoring techniques or similar methods to reduce the requirements for cut slope. Any roots critical to the trees survival must be retained and any non-critical roots in direct conflict with the excavation must be pruned to sound tissue to encourage new root growth. It may be necessary to excavate using a combination of hand digging, small machine excavation and hydro excavation to expose roots in conflict with the proposed excavation and determine whether they can be pruned without having a significant impact on the trees. If it is found that large structural roots must be pruned to accommodate the proposed construction, it may be necessary to remove additional trees to eliminate any risk associated with them.

Blasting

We anticipate that there will be significant blasting required to excavate for the proposed underground parking area. Care must be taken to ensure that the area of blasting does not extend beyond the necessary footprints and into the critical root zones of surrounding trees. The use of small low-concussion charges and multiple small charges designed to pre-shear the rock face will reduce fracturing, ground vibration, and overall impact on the surrounding environment. Only explosives of low phytotoxicity and techniques that minimize tree damage should be used. Provisions must be made to ensure that blasted rock and debris are stored away from the critical root zones of trees.

Arborist Supervision

All excavation occurring within the critical root zones of protected trees should be completed under supervision by the project arborist. Any roots that are in direct conflict with proposed services must be pruned back to sound tissue to reduce wound surface area and encourage rapid compartmentalization of the wound. Where roots can be retained the excavation may consist of a combination of hydro excavation, small excavation equipment and hand digging.

Minimizing Soil Compaction

In areas where construction traffic must encroach into the critical root zones of trees to be retained, efforts must be made to reduce soil compaction where possible by displacing the weight of machinery and foot traffic. This can be achieved by one of the following methods:

• Installing a layer of hog fuel or coarse wood chips at least 20 cm in depth and maintaining it in good condition until construction is complete.
• Placing medium weight geotextile cloth over the area to be used and installing a layer of crushed rock to a depth of 15 cm over top.
• Placing two layers of 19mm plywood.
• Placing steel plates.

Mulching

Mulching is an important proactive step to maintaining the health of the trees to be retained and mitigating construction related impacts and overall stress. Mulch should be made from a natural material such as wood chips or bark pieces and be 5-8cm deep. As much of the area within two times the dripline of the tree should be mulched, both inside and outside of the critical root zone. No mulch should be touching the trunk of the tree. See “methods to avoid soil compaction” if the area is to have heavy traffic.

Servicing

There are no servicing details shown on the plans provided, but it is our understanding that they are to be located outside of the critical root zone of trees to be retained. If services must be located within the critical root zones of trees to be retained it must be reviewed with the project arborist. Installing services within critical root zones will likely require a combination of hand digging, small machine or hydro excavation. If significant roots are encountered that are critical to the health and stability of the trees and they cannot be retained, it may be necessary to remove additional trees.

Landscaping and Irrigation Systems

The planting of new trees and shrubs should not damage the roots of retained trees. The installation of any in-ground irrigation system must take into account the critical root zones of the trees to be retained. Prior to installation, we recommend the irrigation technician consult with the project arborist about the most suitable locations for the irrigation lines and how best to mitigate the impacts on the trees to be retained. This may require the project arborist supervise the excavations associated with installing the irrigation system. Excessive frequent irrigation and irrigation which wets the trunks of trees can have a detrimental impact on tree health and can lead to root and trunk decay.

Arborist Role

It is the responsibility of the client or his/her representative to contact the project arborist for the purpose of:

• Locating the barrier fencing
• Reviewing the report with the project foreman or site supervisor
• Locating work zones, where required
• Supervising any excavation within the critical root zones of trees to be retained
• Reviewing and advising of any pruning requirements for machine clearances

Review and site meeting

Once the project receives approval, it is important that the project arborist meet with the principals involved in the project to review the information contained herein. It is also important that the arborist meet with the site foreman or supervisor before any site clearing, tree removal, demolition, or other construction activity occurs and to confirm the locations of the tree protection barrier fencing.

Please do not hesitate to call us at (250) 479-8733 should you have any further questions. Thank you.

Yours truly,

Talbot Mackenzie & Associates ISA Certified Consulting Arborists

Encl. 10-pages tree resource spreadsheet, 2-page tree resource spreadsheet methodology and definitions, 1-page site plan with tree locations, 3-pages design concept and underground parking, 1-page barrier fencing specifications.

Disclosure Statement

Arborists are professionals who examine trees and use their training, knowledge and experience to recommend techniques and procedures that will improve their health and structure or to mitigate associated risks.

Trees are living organisms, whose health and structure change, and are influenced by age, continued growth, climate, weather conditions, and insect and disease pathogens. Indicators of structural weakness and disease are often hidden within the tree structure or beneath the ground. It is not possible for an Arborist to identify every flaw or condition that could result in failure or can he/she guarantee that the tree will remain healthy and free of risk.

Remedial care and mitigation measures recommended are based on the visible and detectable indicators present at the time of the examination and cannot be guaranteed to alleviate all symptoms or to mitigate all risk posed.