Section 4: Measures to Protect and Maintain the SPEA

Riparian Areas Protection Regulation - Qualified Environmental Professional - Assessment Report

Section 4. Measures to Protect and Maintain the SPEA

1. Danger Trees

No danger trees were identified during the site visit. The arborist did not identify any danger trees during the preparation of the Tree Management Plan for Sub-division and Site Servicing (Gye and Associates Draft Tree Plan dated December 18, 2020) (Appendix A).

Following site servicing, and prior to construction, a danger tree assessor or arborist must review the retained trees adjacent to the proposed construction footprint to evaluate if any risk from danger trees exists. All trees within the proposed SPEA must be retained unless determined by an arborist to be a hazard tree (danger tree). If any hazard trees are identified within the SPEA, the trees should be cut as wildlife trees, if possible. Any danger trees removed within the SPEA must be replaced with native trees species, and the number of replacement trees must be determined based on the 1996 B.C. Ministry of Environment Tree Replacement Criteria.

Some (off-site) boulevard trees are noted for removal along and within the identified SPEA of the ditch along Atkins Road as part of site servicing. These trees are generally identified as being in poor to fair health and in poor structural condition. The arborist recommends removal of these poor condition trees during site servicing and replacement with trees better suited for the conditions. It is recommended that all trees within a SPEA are retained but given the limited nature of the drainage ditch and the lack of LWD requirements for ditches, this proposal is acceptable provided the tree replacement criteria is followed and replanting is focused along the ditch SPEA in compliance with any requirements of a approved Tree Permit under the View Royal Tree Protection Bylaw (No 695), 2009.

2. Windthrow

The trees present on the site and adjacent to the site have been reviewed as part of the Tree Management Plan for Sub-division and Site Servicing (Gye and Associates Draft Tree Plan dated December 18, 2020) but specific recommendation regarding wind firmness are not included (Appendix A).

Some trees noted for removal may be growing in co-dominance with retained trees and their removal may compromise their wind firmness. Trees within the ravine exhibit signs of soil creep, pistol butting and fallen trees are present within the ravine. Removal of existing mature trees for site servicing and building construction may impact the wind firmness of the retained trees (onsite, offsite and within the SPEA).

It is recommended that a qualified arborist or registered professional forester address the risk of windthrow in association with the proposed tree clearing required for the development (site servicing and construction). Stable falling boundaries and any tree treatments (e.g. spiral pruning, crown reduction) to improve wind firmness of new edge trees must be established and completed outside the SPEA.

3. Slope Stability

A slope stability assessment was completed for the proposed subdivision by Ryzuk Geotechnical Engineering and Material Testing dated March 5, 2019 (Appendix A) and a further geotechnical field review and site instruction memo was completed, dated November 24, 2020 (Ryzuk Geotechnical Engineering and Material Testing, Appendix A). A geotechnical setback line from the “limit of disturbance” to protect trees (Tree Management Plan for sub-division and Site Servicing, Gye and Associates, December 18, 2020, Appendix A) and the calculated SPEA for Millstream as determined by this report into its revised plan for unloading the ravine top of bank within Lot 1 and Lot 3 by 3.5 m to 2.0 m bellow existing lot grades. The “limit of disturbance” line is intended as the boundary beyond which no ground disturbance, grading or soil removal can occur as to protect the Millstream SPEA and the protected trees located within the SPEA.

A geotechnical setback of 6.0 m for all structures is then applied for the new unloaded ravine top of bank in Lots 1 and 3 and the existing ravine top of bank in Lot (Figure 3). This setback is based on conventional shallow spread footings. The geotechnical report includes a geotechnical setback line along the small side ravine on the north side of Lot 1 along the “limit of disturbance” line to protect the off site trees and the steep slopes associated with this area (Figure 3).

Recommendations from the Ryzuk Geotechnical Engineering and Material Testing dated March 5, 2019 which still apply include:

• Minimal disturbance of vegetation should occur within the area between the slope crest and the proposed residences.
• Areas subject to excavation/unloading along the slope crest should be excavated with care and re-vegetated as soon as possible.
• Landscaping features should be constructed such that surface flows are not concentrated to discharge at the slope crest. Alternatively, collected water could be conveyed downslope via secured solid pipe network and discharged onto non-erodible soils

Recommendations from the geotechnical field review and site instruction memo, dated November 24, 2020 include:

• Excavation works associated with the slope unloading and site preparations should be carried out with care in accordance with recommendations from a qualified professional.
• Excavation cut slopes should be prepared ins a stable configuration to ensure stability over the short to medium term in the event the lots are not developed immediately (e.g. 1:1 slopes).

4. Protection of Trees

General recommendations on the protection of trees is provided in the Gye and Associates Tree Management Plan for Sub-division and Site Servicing dated December 18, 2020 (Appendix A). The Tree Management Plan also includes markup of all anticipated on-site tree removals for lot buildout. Arborist review and support will be required to allow site servicing and house construction to avoid impacts to retained trees, trees within the SPEA and off-site trees.