Appendix: Tree Retention Report - Talbot Mackenzie & Associates

Tree Retention Report for 148 Atkins Road

Assignment

Review the preliminary subdivision and site servicing plans and prepare a tree retention report to be used during removal of the existing residence, and proposed two lot subdivision of the 148 Atkins Road property.

Methodology

Existing tag numbers were used to identify each bylaw-protected tree onsite and several other non-bylaw protected trees that were picked up on the survey. One additional bylaw-protected tree was tagged by us on the subject property and two trees on the neighbouring properties were not tagged, but are included in the attached tree resource spreadsheet. Information such as tree species, size (dbh), critical root zone (crz), health and structural condition, relative tolerance to construction impacts and general remarks and recommendations was included in the attached tree resource spreadsheet.

Observations

The site terrain is steep rock, which will likely require some blasting to level the building footprints on the two proposed lots. Most of the bylaw-protected trees on the site are located around the perimeter of the proposed building envelopes, where they may be possible to retain, providing that their critical root zones can be adequately protected during blasting, excavation and house construction.

Mitigation of impacts

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 to be erected 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 (see attached diagram). 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

Barrier fencing must be erected prior to the commencement of demolition activity. If Leyland cypress trees #108 and 109 are to be retained, removal of the cantilevered portion of the existing residence must be removed carefully, where it encroaches into the critical root zones of these trees. We recommend that solid hording be used to protect the trunks of these trees during demolition if these trees are to be retained.

Building Envelopes

Lot A

• Two bylaw-protected Leyland cypress trees #109 and 108 are growing near the southwest corner of Lot A, where they could potentially be impacted by house construction on the proposed new lot, depending on the final house design.
• A bylaw-protected flowering plum tree #0946 is growing near the south property line where it may be impacted, depending on final house design. If these trees are to be retained, we recommend that all excavation within the critical root zones, including working room beyond the foundation and any cut slope requirements, be performed under arborist supervision. If significant roots are encountered during excavation, we may recommend that the trees be removed.
• Cherry trees #106 and 110 are located within the proposed building envelope and will likely require removal, depending on the final house design.

Lot B

• There are no bylaw-protected trees located within the proposed building envelope.
• Arbutus 102 and Douglas-fir 101 are located in the proposed rear yard setback, where they may be possible to retain providing that their critical root zones can be adequately protected during blasting and rock removal.
• An untagged Douglas-fir (no tag 1) located on the neighbouring property at 144 Atkins Road could potentially be impacted, depending on the extent of the required blasting. We recommend that the proposed residence on Lot B be designed so that no excavation is required within the critical root zone of this tree.

The project arborist must be onsite to supervise excavation within the critical root zones of the above-mentioned trees.

Driveway Footprints

Lot A

• No bylaw-protected trees are located within the proposed driveway footprint to proposed Lot A.

Lot B

• According to the plans supplied, the existing driveway footprint will be used to access proposed Lot B. Big leaf maple #105 and cherry #104 are located along the edge of the existing driveway where they may be possible to retain, provided the existing driveway base can be used and no significant grade changes are required within the trees’ critical root zones.

Servicing/stormwater Management

Lot A

• According to the plans provided, the proposed water and sewer connections to Lot A are outside the critical root zones of bylaw-protected trees.
• The stormwater management system encroaches into the critical root zone of flowering plum #111. The retention of this tree will likely be a field decision at the time of excavation, and dependant on the extent of excavation required for the stormwater management system.

Lot B

• According to the plans provided, the existing water service is to be re-used to service proposed Lot B. The proposed underground sewer connection will likely encroach into the critical root zones of flowering plum #103 and Big leaf maple 105. If these trees are to be retained, we recommend that the project arborist be onsite to supervise excavation within their critical root zones. If significant roots are encountered during excavation, the service must be tunnelled underneath. If these trees are heavily impacted by excavation we may recommend that they be removed.
• The proposed stormwater management system for proposed Lot B does not encroach into the critical root zones of bylaw-protected trees.
• There are no details of the hydro or gas connections on the plans provided. We recommend that these services be located outside of critical root zones of bylaw-protected trees to be retained. If they are located within the critical root zones of bylaw-protected trees, the project arborist must be onsite to supervise excavation within the critical root zones.

Blasting and rock removal

• We anticipate significant blasting requirements on proposed Lot B, which could potentially impact Douglas-fir trees located on the neighbouring property at 144 Atkins Road as well as Douglas-fir #101 and arbutus 102 located within the proposed rear yard setback.
• We recommend that a critical root zone of 8 metres be left undisturbed, for the 75cm dbh Douglas-fir (no tag 1), located on the neighbouring property at 144 Atkins Road. If it will not be possible to protect the critical root zone of this tree due to blasting requirements, this tree may have to be removed. Once we see detailed building plans, we can comment further on the impacts to the trees surrounding the building envelope on proposed Lot B.

If it is necessary to blast areas of bedrock near critical root zones of trees to be retained, the blasting to level these rock areas should be sensitive to the root zones located at the edge of the rock. Care must be taken to assure that the area of blasting does not extend into the critical root zones beyond the building and road footprints. The use of small low-concussion charges, and multiple small charges designed to pre-shear the rock face, will reduce fracturing, ground vibration, and reduce the impact on the surrounding environment. Only explosives of low phytotoxicity, and techniques that minimize tree damage, are to be used. Provisions must be made to store blast rock, and other construction materials and debris, away from critical tree root zones.

Pruning

Lot A

• Depending on the final house design, some clearance pruning may be required from Leyland cypress #109 to attain adequate clearances from the residence on proposed lot A. Once detailed building plans are provided, we can comment further on clearance pruning requirements.

Lot B

• Depending on the final house design, some clearance pruning may be required from the 75cm dbh Douglas-fir (no tag 1) located on the neighbouring property at 144 Atkins Road as well as trees #101 and 102. Once detailed building plans are provided, we can comment further on clearance pruning requirements.

Conclusion

Based on the preliminary subdivision and site servicing plans, it may be possible to retain the bylaw-protected trees located around the perimeter of the proposed building envelopes, providing their critical root zones can be adequately protected during construction. We recommend that the residences on both lots be designed so that they do not encroach heavily within the critical root zones of bylaw-protected trees.

When designing the residence for proposed Lot B, we recommend that a critical root zone of 8 metres be left undisturbed, for the 75cm dbh Douglas-fir (no tag 1), located on the neighbouring property at 144 Atkins Road. If the tree must be retained, and it is desirable to encroach closer to the tree within the proposed building envelope, we recommend that exploratory excavations be carried out. As there is limited soil volumes it is possible that there are few critical roots in this area. If it will not be possible to protect the critical root zone of this tree due to blasting requirements, this tree may have to be removed. Once we see plans showing house designs for each lot, we can comment further on specific tree retention on both lots.

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

Yours truly, Talbot Mackenzie & Associates

Graham Mackenzie & Tom Talbot ISA Certified, & Consulting Arborists

Enclosures: — Tree Resource Spreadsheet, Tree location diagram, 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 the health and structure of individual trees or group of trees, 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 nor 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.