Arbor Vitae Tree Consultants Tree Assessment Report

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Lynne Clarke
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Arbor Vitae Tree Consultants Tree Assessment Report Bob Ambardar Manager City of White Rock Engineering and Aelicia Otto Arborist/Horticulturalist City of White Rock 1-October-2014 Re: Review of

3 Arbor Vitae Tree Consultants Tree Assessment Report Bob Ambardar Manager City of White Rock Engineering and Aelicia Otto Arborist/Horticulturalist City of White Rock 1-October-2014 Re: Review of sidewalk trees and tree sites Johnston Rd corridor. Summary Between the of September 2014, 32 trees and planting sites along both sides of Johnston Rd between North Bluff and Thrift were visually inspected. The trees are a mix of 4 different genus: 19 Sweetgum Liquidambar styraciflua 8 Japanese Flowering Cherrys Prunus serrulata 3 Red Maples Acer rubrum 1 English Oak Quercus rubra The objective was to: a. Provide a snapshot of the current condition of the trees b. Assess the level of damage to infrastructure adjacent to the tree planting sites c. Make preliminary recommendations concerning likelihood of successful retention. Based on preliminary findings it may be possible to successfully retain ~15 of the trees Sweetgum Liquidambar styraciflua 2 Japanese Flowering Cherrys Prunus serrulata 1 Red Maples Acer rubrum 1 English Oak Quercus rubra Observations The majority of the trees appear to have been planted between years ago, most installed in sidewalk sites. The method of planting and site preparation has contributed to trees with poor root structure, significant soil heaving with damage to infrastructure. In spite of this, the above ground portion of many trees is in fair to good condition. A snapshot of the current condition of the trees and sites reveals the following: 28 of 32 trees with root defects 27 of 32 tree well sites with a history of damage 21 of 32 trees with health and vigour rated fair or better 10 of 32 trees where retention is recommended and likelihood of success is good * 15 of 32 trees where retention is recommended and likelihood of success is fair * (* Recommendation for and success of retention are based on current site characteristics as well as overall tree condition.) Prepared by Arbor Vitae Tree Consultants P.O.Box 1185 Fort Langley BC V1M2S arborvitaetree@gmail.com 1/5

Recommendations i. Create 4 working categories: 1. Trees to be removed (~17) 2. Number and location of replacements (0) 3. Trees that require further inspection and analysis (~12) 4.

4 Recommendations i. Create 4 working categories: 1. Trees to be removed (~17) 2. Number and location of replacements (0) 3. Trees that require further inspection and analysis (~12) 4. Trees to be retained and infrastructure repaired (3) Remember that trees will be removed from one category to another as more information becomes available i.e. as sections of sidewalk are removed to expose tree root structures, some that were considered for retention may be re-categorized into remove and replace. Soil/root heaving. ii. Trees considered for retention Prior to beginning any on-site work a thorough review of current literature and techniques for retaining existing large trees urban settings should be carried out. Have a well-documented plan prior to beginning (understanding that adjustments will be necessary as new information comes to light). Anytime material, whether soil, concrete or asphalt is being removed from the area inside the critical root zone (~5 X trunk diameter) there will be risks: o Possibility that the stability of the tree (i.e. the ability to stay vertical) may be o compromised. Change in soil environment that may result in disease pathogens being introduced into the root zone. Carefully remove the hard landscape (curb, gutter, sidewalk) from around the tree. It is typical that there will be root damage as a result. Try to minimize this. Using a hydro-vac truck or similar techniques excavate the sub-base soils from the trunk root flair and expose to minimum depth the root mass of the trees. Damage to the roots will occur and some roots will need to be cut in order to facilitate retention of the tree and re-building the site. Assess, make a final decision concerning retention. All work around the trees should be carried out under the supervision of the City Arborist or other qualified person and all work should be documented. Contract language is particularly important in projects that involve trying to assess and retain trees. Careful review and agreement by all departments involved is critical for success. iii. Planting replacement trees Planting techniques have improved tremendously over the last 2 decades. Almost all of the trees under discussion have been badly planted in poorly prepared sites. A review of the literature will provide a number of designs with recommendations concerning how to successfully plant trees in hard landscape settings. The City has engaged the services of a qualified Landscape Architect to review current best practices for design and construction of sidewalk planting sites. Adequate root room is the most important thing for the establishment and long-term survival of trees while minimizing potential for damage to sidewalks and curbs. Lack of water is the single most limiting factor in successful establishment of new trees. Where space is adequate choose tree species that establish quickly, grow to a reasonable size over 10 years, and have a proven track record. It may be that positions for replacement trees have to be adjusted from the original planting locations. Remember that underground services, adequate space above and below ground, Prepared by Arbor Vitae Tree Consultants P.O.Box 1185 Fort Langley BC V1M2S arborvitaetree@gmail.com 2/5

5 street use as well as a cohesive street presence all need to be considered when deciding where trees will go. Discussion Questions that should be answered prior to moving forward: What is the structure and condition of the below ground portion of the trees? What impact of proposed redesign for the street have on successful retention of the trees and if necessary can construction details be adjusted? How best to design for a cohesive overall streetscape? What are reasonable expectations for the retained trees? What is the long-term strategy for vegetation on Johnston corridor? My experience as the Arborist for New Westminster included 2 projects very similar to this. In the end a nuanced approach worked best. To reiterate, key points include: Investigation and analysis based on what is revealed when material from around the tree is removed. Often what is uncovered will quickly point in the best choice, be it retention or removal and replacement. A workable plan to repair the damage and to control as much as possible future damage should be drafted and any change to the layout of the hard landscape can be implemented. In other words you investigate as thoroughly as you possibly can and if you do not find a good reason to not proceed with retention then you go ahead. Suitability for retention will depend on a number of factors and ultimately will be made on a tree-by-tree basis. It is impossible to know the full long term impact that renovation and retention will have on a particular trees. All that can be assured is that the work is undertaken using the best industry agreed upon principles of mature tree management in sidewalk sites. This situation is common throughout the industrialized world. Many designers, engineers and arborists have undertaken projects like this. Have a long range plan that includes retention of some of the best trees, how new plantings will fill in spaces on the street, and how re-development and associated off site works can be incorporated into the overall vegetation plan for the street. Try to maintain the ambiance on the street. Repairs can usually be made to infrastructure that will manage tripping hazards, at least in the short term (5-7 years) Create a sidewalk tree planting design that provide the largest volume of soil possible and where feasible irrigation. There are a number of good designs that other municipalities have created. Each tree that is being considered for retention has grown and evolved in a unique situation. Any disruption to this environment will have risks. Exposing the below ground portion of any tree and judiciously cutting roots to accommodate sidewalk repair/re-design has risks. Limitations Recommendations for retention and the likelihood of success as outlined in this report are based on the tree and site as they were observed on the day of assessment. It is impossible to predict the full effect on tree health and stability that root disruption may have. It is also impossible to predict the long-term impact on tree health that reconstructing the infrastructure (sidewalks, curbs etc) adjacent to retained trees may have. ~ Prepared by Arbor Vitae Tree Consultants P.O.Box 1185 Fort Langley BC V1M2S arborvitaetree@gmail.com 3/5

6 Limitations of this Assessment It is Arbor Vitae Tree Consultants policy to attach the following clause regarding limitations. We do this to ensure that developers or owners are clearly aware of what is technically and professionally realistic in retaining trees. The assessment of the tree(s) presented in this report has been made using accepted arboricultural techniques. These include a visual examination of the above-ground parts of each tree for structural defects, scars, external indications of decay such as fungal fruiting bodies, evidence of insect attack, discolored foliage, the condition of any visible root structures, the degree and direction of lean (if any), the general condition of the tree(s) and the surrounding site, and the proximity of property and people. Except where specifically noted in the report, none of the trees examined were dissected, cored, probed, or climbed, and detailed root crown examinations involving excavation were not undertaken. Notwithstanding the recommendations and conclusions made in this report, it must be realized that trees are living organisms, and their health and vigour constantly change over time. They are not immune to changes in site conditions, or seasonal variations in the weather conditions. While reasonable efforts have been made to ensure that the trees recommended for retention are healthy, no guarantees are offered, or implied, that these trees, or any parts of them will remain standing. It is both professionally and practically impossible to predict with absolute certainty the behavior of any single tree or group of trees or their component parts in all circumstances. Inevitably, a standing tree will always pose some risk. Most trees have the potential for failure in the event of adverse weather conditions, and this risk can only be eliminated if the tree is removed. Although every effort has been made to ensure that this assessment is reasonably accurate, the trees should be re-assessed periodically. The assessment presented in this report is valid at the time of inspection. Notwithstanding the recommendation made in this report W.J. Wilde /Arbor Vitae Tree Consultants accept no responsibility for the implementation of all or any part of this plan, unless we have specifically been requested to examine said implementation activities. Approval and implementation of this plan in no way implies any inspection or supervisory role on the part of W.J. Wilde/Arbor Vitae Tree Consultants. In the event that inspection or supervision of all or part of the implementation of the plan is requested, said request shall be in written and the details agreed to in writing by both parties. Any on site inspection or supervisory work undertaken by W.J. Wilde/Arbor Vitae Tree Consultants shall be recorded in written form and submitted to the client as a matter of record. The report shall be considered a whole, no sections are severable, and the report shall be considered incomplete if any pages are missing. This report is the sole property of W.J. Wilde/Arbor Vitae Tree Consultants and the client(s) for whom it was prepared. It is not intended for public review without the written authorization of both parties. On behalf of Arbor Vitae Tree Consultants, Prepared by Arbor Vitae Tree Consultants P.O.Box 1185 Fort Langley BC V1M2S arborvitaetree@gmail.com 4/5

7 (1-October-2014) William Wilde, ISA Certified Arborist #0295/ TRAQ Certified Prepared by Arbor Vitae Tree Consultants P.O.Box 1185 Fort Langley BC V1M2S /5

DUNSTER & ASSOCIATES Environmental Consultants Ltd.

DUNSTER & ASSOCIATES Environmental Consultants Ltd. Risk Assessment of Two Black Cottonwoods at Georgia Avenue at the south east corner of 577 6 th Street Dr. Julian A. Dunster, R.P.F., R.P.P., M.C.I.P.,