Loading...
HomeMy WebLinkAboutPWD-025-21Clarington Staff Report If this information is required in an alternate accessible format, please contact the Accessibility Coordinator at 905-623-3379 ext. 2131. Report To: General Government Committee Date of Meeting: June 21, 2021 Report Number: PWD-025-21 Submitted By: Stephen Brake, Director of Public Works Reviewed By: Andrew C. Allison, CAO Resolution#: GG-414-21, File Number: C-227-21 Report Subject: Red Oak Tree at 21 Beech Ave By-law Number: Recommendations: 1. That Report PWD-025-21 be received; 2. That Council provide direction to staff respecting the implementation of the preservation plan for the Red Oak Tree at 21 Beech Avenue in Bowmanville; 3. That if the preservation plan is approved, the Self -Insured Losses Reserve be utilized to fund the costs up to $56,100; and 4. That all interested parties listed in Report PWD-025-21 and any delegations be advised of Council's decision. Municipality of Clarington Report PWD-025-21 Report Overview Page 2 This report addresses Council Resolution #C-160-21 that requested Staff report back on a cost estimate to preserve, trim and support the Red Oak Tree at 21 Beech Avenue in Bowmanville. The report also seeks Council's direction on whether to proceed with the Tree Preservation plan prepared by Richardson Tree Care and the approval of a funding source to complete the work. 1. Background 1.1 On June 30, 2020, a large limb from the Red Oak Tree fronting 21 Beech Avenue fractured and landed on the adjacent house. The weight of the failed branch when being craned off was 5,600 pounds after being thinned. The failure of the limb did not occur as a result of any storm conditions or other external factors. 1.2 Recognizing the significance of the Red Oak Tree to the Older Bowmanville Neighbourhood, staff commissioned an independent Inspection and Assessment Study with Ontario Line Clearing & Tree Experts Inc. The study was completed in September 2020 and provided Staff with in-depth results that included sonic tomography and resistance drillings to further aid in determining the overall health of the tree. 1.3 The findings of the study concluded that the Red Oak tree is in the mid to late ancient developmental life stage. Features of over -maturity that are present include a declining crown, heartwood decay and segmentation into distinct functional units. There are, however, also areas of very good tree health evidenced by strong rib growth and striations. 1.4 The inspection and assessment study identified that the two lower limbs of the tree have the highest likelihood of failure in the future and may cause significant damage. These branches are relatively weakly attached and are likely to fall due to gravity without the addition of dynamic forces such as wind, rain, wet snow or freezing rain. There are also many other smaller limbs higher up in the canopy with very similar poor branch attachments that could fail at any time. 1.5 The report confirms that the likelihood of the two large lower limbs that extend over the sidewalk and roadway are likely to fracture within the next five years. Consideration of reducing the limbs by more than 1.5m will likely result in the death of the limbs. Municipality of Clarington Page 3 Report PWD-025-21 1.6 Management options that are outlined within the report to address the existing tree conditions are listed as follows: fi11111111111CZa',=0 F I 2. Addition of props and pruning as necessary 3. Do nothing 1.7 A copy of the Tree Inspection and Assessment Study prepared by Ontario Line Clearing & Tree Experts Inc., dated September 22, 2020, is provided as Attachment 1. 1.8 On March 16, 2021, Mr. Bill Humber and Mr. Rick McEachern made presentations to the Clarington Heritage Committee requesting heritage conservation and enhancements for the Red Oak Tree. The purpose of the heritage designation would ultimately require protection and preservation of the tree. 1.9 Concurrent with the Clarington Heritage Committee review, Public Works staff also requested comment from the Durham Municipal Insurance Pool (DMIP) respecting the findings of the Inspection and Assessment Study. The DMIP responded by recommending that "the Municipality take steps to mitigate the risk of further failure of this tree. As for the options of either removing it or pruning/adding props to secure the tree, this is the decision of the Municipality." 1.10 On April 20, 2021, the Clarington Heritage sub -committee concluded that based on extensive research and the information provided to the Committee, they found insufficient cultural heritage significance to recommend support for individual designation of the tree under Part IV of the Ontario Heritage Act. 1.11 At the regular Council meeting of May 3, 2021, Mr. Rick McEachern made a presentation requesting a similar course of action in an effort to protect the Red Oak Tree. In response to the request, Clarington Council passed Resolution #C-160-21, that directed Staff to report back on a cost estimate of preserving, trimming and supporting the Red Oak Tree. 2. Analysis 2.1 Public Works staff commissioned a further study in April 2021 by Richardson Tree Care to determine the full scope of Option 2 above for Generalized Tree Preservation and Pricing. 2.2 The consultant's report suggested that the Red Oak Tree at 21 Beech Avenue was estimated to be approximately 230 years old and if properly cared for could potentially live for another 50 years. Municipality of Clarington Report PWD-025-21 Page 4 2.3 The primary preservation mechanism recommended for the retention of the tree and the support for the two lowest over -extended heavy limbs includes the use of wooden utility poles and wire cabling. Pruning is also required to remove existing deadwood and to reduce the overall size of the tree to encourage new interior growth. It is further recommended that the size of the tree should be further reduced over the next 20 to 50 years. 2.4 The tree preservation plan will require that a number of steps be implemented including a design of the maypole and cabling system, obtaining permission to install poles on private property, installation of four wooden utility poles ranging in height from 25 to 75 feet, pruning of existing deadwood, reduction of the crown and the provision of soil invigoration and mulching. 2.5 Generalized costs for the tree preservation program is estimated at $56,100. It should be noted that these estimated costs do not include future fees associated with yearly monitoring and for additional pruning likely in year 8-10. A cost breakdown of the proposed workplan is provided as follows. Workplan Estimated Cost Design of Support System, Create Detailed Pruning Specifications $1,500 Engineering of Support System 5,000 Deadwood Removal & Pruning 3,000 Supervision of Pruning 800 Purchase of Poles 23,000 Hydrovac Service for Pole Installation 3,500 Supervision of Hydrovac 500 Pole Installation 3,500 Supervision of Pole Installation 800 Cabling Equipment 7,500 Cabling installation 4,000 Supervision of Cabling Installation 1,000 Soil Invigoration & Mulching 2,000 Total $56,100 2.6 A copy of the Generalized Tree Preservation and Pricing Study prepared by Richardson Tree Care, dated April 19, 2021, is provided as Attachment 2. 3. Concurrence This report has been reviewed by the Director of Financial Services/Treasurer who concurs with the recommendation for the source of funding if Council decides to preserve the tree. Municipality of Clarington Report PWD-025-21 4. Conclusion Page 5 It is respectfully recommended that Council provide direction to Staff regarding the preservation of the Red Oak Tree fronting 21 Beech Avenue in Bowmanville. Based on the condition of the tree and the safety risks that are currently present, the Red Oak Tree must either be removed or be adequately supported using a maypole and cable system. Staff Contact: Stephen Brake, Director of Public Works, 905-623-3379 ext. 2903 or sbrake@clarington.net. Attachments: Attachment 1 — Tree Inspection and Assessment of Red Oak Attachment 2 — Generalized Tree Preservation and Pricing Interested Parties: The following interested parties will be notified of Council's decision: Clarington Heritage Committee Rick McEachern Attachment 1 to Report PWD-025-21 Tree Inspection &Assessment of Red Oak, 21 Beech Street, Bowmanville, Ontario September 22, 2020 Prepared for: Ken Mercer Supervisor Public Works Department Municipality of Clarington 40 Temperance Street Bowmanville, ON L 1 C 3A6 905-263-2291 1-800-563-1195 KMercer@clarington.net Prepared by: Michael Richardson Ontario Line Clearing & Tree Experts Inc. 7790 Telephone Rd Cobourg, ON K9A 4,17 613-475-2877 richardsontreecare(a)gmail.com Red Oak, 21 Beech St., Bowmanville Page 1 of 27 Contents Introduction.................................................................................................................................... 2 Limitsof the Assignment................................................................................................................ 2 SubjectTree.................................................................................................................................... 2 Photographs of Subject Tree....................................................................................................... 3 Photograph(s) of Noted Defects/Features.................................................................................. 4 TreeHealth...................................................................................................................................... 4 Failure Mode Assessment of the Failed Limb................................................................................. 6 Advanced Inspection of Tree.......................................................................................................... 8 Photograph(s) of sensors installed on tree and cross-section height ........................................ 8 Tomogram of Cross-section Shown in Above Photograph......................................................... 9 Tomogram with Mechanical Interpretation of Strength Loss ................................................... 10 Resistograph° Drilling Profiles.................................................................................................. 10 Assessment of Defects/Feature................................................................................................ 12 Full Tree Risk Assessment......................................................................................................... 18 ManagementOptions................................................................................................................... 18 PossibleSupport Methods............................................................................................................ 19 ReinspectionPeriod...................................................................................................................... 21 Appendix A — Assumptions and Limiting Conditions.................................................................... 22 Appendix B — Interpretation of Resistance Drilling Profiles......................................................... 23 Appendix C — Interpretation of Sonic Tomography Images.......................................................... 24 Appendix D — Interpretation of Mechanical - Sonic Tomography Images .................................... 26 Appendix E — Certificate of Performance..................................................................................... 27 ©Michael Richardson, B.Sc.F., BCMA, MTCU Qualified Arborist September 22, 2020 Red Oak, 21 Beech St., Bowmanville Page 2 of 27 Introduction At the request of Jon McNairn I inspected and completed an advanced assessment of a Red Oak immediately east of the sidewalk at 21 Beech Street, Bowmanville. Limits of the Assignment • This report is based on visual inspection along with sonic tomography and resistance drillings; • There was no inspection of roots not clearly visible above soil level; • This report does not provide any guarantee to stability or survivability of the tree; • This report is not prepared for use in any legal proceeding. Subject Tree Species: Red Oak (Quercus rubra) Size — diameter at breast height — 186 cm Location - in front yard between the sidewalk and the house at 21 Beech St. Lower limbs reach from the tree to the west side of road and from the tree to the house and the driveway to the south. The sidewalk has been adjusted to flow around the tree. Presenting defects/features — a large limb on the north east corner of the tree has fractured this past summer and landed on the house. The broken branch union reveals a cavity centred in the stem. ©Michael Richardson, B.Sc.F., BCMA, MTCU Qualified Arborist September 22, 2020 y ;•• t ��� •i. s1. '+ �' � • jai{ ..y',f�r�� .. eke M � � '' ' � 7 E• _", ,�c � -Mt ,� F-^��_ • � ' / { 'Y-- � , '�f 3 ,01 �;_ fT-'{•may � y,..i �� 1 t a r R� y � r� r✓ 1 #':''� T AL �� r� ✓t' ! �., .y�ai*�., y,+`4.:a��,� ,+ '. ! � I ob�a'r, 6t � j Vast •. 1 : I,"t rA y J. � ♦ ,.Syr Red Oak, 21 Beech St., Bowmanville Page 4 of 27 Photograph(s) of Noted Defects/Features Tree Health The tree is an over -mature tree within terms of morpho-physiological age. A couple of distinct features of over -maturity are present: declining crown, heartwood decay, and segmentation into distinct functional units. There are still areas of very good growth as evidenced by strong rib growth and striations. The lower two limbs are over -extended (extending beyond the natural canopy outline), have had most interior branches and sprouts removed, and bear leaves largely in the outer 3-4 m. Reducing these limbs by more than 1.5 m will likely result in the death of the limbs. ©Michael Richardson, B.Sc.F., BCMA, MTCU Qualified Arborist September 22, 2020 Red Oak, 21 Beech St., Bowmanville Page 5 of 27 Morpho-physiological Age of Trees Young maturing phase: Early to late maturity: Early-, mid- & late -ancient Apical dominance Lower units break free from phases: crown retrenchment & apical dominance reiterative growth (a) 0 1� The crown has been heavily pruned in the past as evidenced by the large pruning wounds. The crown is in decline as many dead branches and thin areas exist. ©Michael Richardson, B.Sc.F., BCMA, MTCU Qualified Arborist September 22, 2020 Red Oak, 21 Beech St., Bowmanville Page 6 of 27 The tree has begun to segment into functional units. This means that a functional unit of a distinct section of the tree consisting of a limb or branch with associated foliage, a portion of the trunk and roots connected through a buttress roots has formed that is acting independently of the rest of the tree. This is particularly evident on the two lower limbs. If a functional unit is over -pruned or the limb completely removed the associated stem and roots will die. Failure Mode Assessment of the Failed Limb The failed limb fractured because there was no integration of the branch fibers into the trunk on the upper portion of the of limb combined with the weight applied to the long lever arm. This is a very common failure mode in large oaks. The cavity within the trunk played no role in the failure. There are very well -formed growth ribs on the underside of the failed limb. The large growth ribs are pushing the limb up but the traditional tension mode of angiosperms was lost many years ago on this limb. There is no connection between the limb and the trunk on the upper half of the limb. This is identified by included bark, the loss of the branch bark ridge. Near vertical apparent connection interface, and in the photo of the fracture the loss of toothpick like fibres above the fracture line. 7. Y, /'�: ; a 'A�i/ •.,tee � � _ r �'` ©Michael Richardson, B.Sc.F., BCMA, MTCU Qualified Arborist September 22, 2020 Red Oak, 21 Beech St., Bowmanville Page 7 of 27 ©Michael Richardson, B.Sc.F., BCMA, MTCU Qualified Arborist September 22, 2020 Red Oak, 21 Beech St., Bowmanville Page 8 of 27 Advanced Inspection of Tree The area of the trunk was inspected using Rinntech Arbotom® Sonic Tomography and Rinntech Resistograph®. The yellow tape and sensors indicate the level of the inspection. Measuring point 1 is to magnetic north. Photograph(s) of sensors installed on tree and cross-section height ter.::.•=�sp.�.�7 ©Michael Richardson, B.Sc.F., BCMA, MTCU Qualified Arborist September 22, 2020 Red Oak, 21 Beech St., Bowmanville Page 9 of 27 Tomogram of Cross-section Shown in Above Photograph Project: 21 Beech St. B.w tulle Location: H: 0 cm I 50 cm i Tree: Tree species: Quemus 191 cm Date: 202009-03 t ©Michael Richardson, B.Sc.F., BCMA, MTCU Qualified Arborist September 22, 2020 Red Oak, 21 Beech St., Bowmanville Page 10 of 27 Tomogram with Mechanical Interpretation of Strength Loss NcteU 21 Beech St. Bowm Ile Location: Tree: Tree species: Quemus ❑sts. 2020-09-03 The tomogram shows loss of solid wood in the cross-section primarily progressing from the center (pith) area towards the edge. Green indicates solid wood while yellow indicates incipient decay and reds and purple complete loss of physical structure. The second tomogram image indicates a maximum loss of 9% of the load carrying capacity of the cross-section as compared to the geometrically same cross-section with no decay. Central heartwood decay is expected and typical of large old oaks. Resistograph® Drilling Profiles Resistance drilling confirms the decay is centrally located and there is a solid intact shell wall. The tree was drilled on the east face at the top of the red ribbon. The wood was intact to a depth of 50 cm. ©Michael Richardson, B.Sc.F., BCMA, MTCU Qualified Arborist September 22, 2020 Red Oak, 21 Beech St., Bowmanville Page 11 of 27 00000448 20200903 0000 Relative Density 550 ---------------- -----------*---------- 500 ------------`---------- 450 -----------=-- =----'----------------------- 400 ------------------------------------I------------------------- -I ----------- ---------- '----- ----- - - ---------- 350 -----------•-----------'------------`-----------'------------`---------- '------------` 300 --i---- ---------- - 250 --- ry------------ 200 ----------- 150 ------ '------------` 100 --- ------------------------- 50 --- --- -------- -------- 0 0 50 100 150 200 250 300 350 400 450 500 ©Michael Richardson, B.Sc.F., BCMA, MTCU Qualified Arborist September 22, 2020 Red Oak, 21 Beech St., Bowmanville Page 12 of 27 The tree was drilled at the southwest side near measuring point 10. This are was expected to have the thinnest shell -wall. There is approximately 27 cm of intact wood at this location. Relative Density 150 100 50 intact (55%) intermediate (11 %) decayed (27%) Bark (7%) Assessment of Defects/Feature The tree has two very large lower limbs and many large limbs in the canopy. There is a large limb over the road that stretches across the road and intersects another tree. The limb is relatively horizontal with most of the leaves situated at the distal ends. There are very few branches and sprouts along the limb. ©Michael Richardson, B.Sc.F., BCMA, MTCU Qualified Arborist September 22, 2020 t A' u ski ,+. t . Asa � � ��., � • - " �:"''�.. e " `-a• .S .aa,i ti yy a i I ir IA o. At Red Oak, 21 Beech St., Bowmanville Page 16 of 27 ',tk- " r f: It is my opinion that the two lower limbs will fail in the next five years. These limbs can fail at any time as the length of the lever arm, weight, and poor branch attachments all combine to make it likely the limb will fail do to gravity alone with no added dynamic forces. There are many other smaller limbs in the canopy with very similar poor branch attachments. Many of these can fail at any time. ©Michael Richardson, B.Sc.F., BCMA, MTCU Qualified Arborist September 22, 2020 Red Oak, 21 Beech St., Bowmanville Page 17 of 27 •E, (AA, �rtr�i► ©Michael Richardson, B.Sc.F., BCMA, MTCU Qualified Arborist September 22, 2020 Red Oak, 21 Beech St., Bowmanville Page 18 of 27 Full Tree Risk Assessment The parts of the tree with the highest likelihood of failure and that may cause significant damage are the two lower limbs. The limbs are relatively weakly attached and are likely to fall due to gravity without the addition of dynamic forces such as wind, rain, wet snow, or freezing rain. The consequences of failure are minimal over the lawn, but either limb may fall onto the sidewalk and have the potential to hit walkers etc., the limb over the road has the potential to strike those on the sidewalk as well as passing and parked vehicles. It is not possible for me to determine the occupancy under the tree as COVID- 19 has likely altered street parking. The tree managers are better equipped to determine occupancy and ultimately overall risk associated with the limb falling onto the road and sidewalk. Should either of these limbs fail and strike a person the likely outcome is severe injuries or death. If a limb falls and hits a parked or passing vehicle the consequences can be expected to be extensive monetary damage and perhaps severe injuries or death to occupants. Risk has a large component of occupancy. It is clear that the sidewalk is regularly used but by no means is the area under the tree occupied more than perhaps 10% of the year. The area under the tree may have higher occupancy than the sidewalk if cars are parking regularly. It is my opinion the likelihood of failure of the southern limb in the next five years is probable, the likelihood of impacting someone on the sidewalk is low, but the consequences of failure is severe resulting in the limb having a risk rating of low. It is my opinion the likelihood of failure of the limb over the road in the next five years is probable, the likelihood of impacting someone on the sidewalk or a vehicle is medium, but the consequences of failure is severe resulting in the limb having a risk rating of moderate. The overall risk rating of the tree currently is MODERATE. Management Options The three primary management options for this tree are: 1. Removal 2. Addition of props and pruning as necessary 3. Do nothing ©Michael Richardson, B.Sc.F., BCMA, MTCU Qualified Arborist September 22, 2020 Red Oak, 21 Beech St., Bowmanville Page 19 of 27 Option 1. It is clear to me from my time visiting the tree that many locals appreciate and love this tree. I believe the removal may be an inappropriate option. Option 3. Do nothing will result in the collapse of the lower limbs and gradual failure of the crown, limb by limb. It is my opinion that doing nothing will result in the failure of the two lower limbs within the next five years even in normal weather. The limbs are relatively weakly attached and are likely to fall due to gravity without the addition of dynamic forces such as wind, rain, wet snow, or freezing rain. It is generally considered that people and property are the primary objects that need protecting by mitigating tree risk. It is also worth remembering that the tree itself is a target and there are many benefits that trees provide. The loss of the subject tree will result in the loss of biological, physical, and physiological that can never be replaced. Option 2. It is my opinion that to retain the tree the two lower limbs must be mechanically supported and the upper crown supported as necessary. This work will require a complete inspection of tree to determine likely failure points, the loads they represent and the requirement of the support materials. Pruning, including dead- wooding and crown reduction must be specified based upon the need to maintain as much live canopy as possible. Possible Support Methods In my opinion the tree must be supported to reduce the likelihood of failure. Possible support methods are shown. All involve support with built structures (props or may -poles) as more traditional cables will not work in this case. ©Michael Richardson, B.Sc.F., BCMA, MTCU Qualified Arborist September 22, 2020 ���x. •�., r7 • Y + „� ;� • " ' ,.� � Yam` ; Ax it Yi M. '.q. Of Ilk Ar & ?y+ lye ', 7,i . {: •6: 3 1 Red Oak, 21 Beech St., Bowmanville Page 21 of 27 Reinspection Period If the limbs and crown are not supported the tree should be inspected: 1) After each storm event to determine if a vertical crack between top side of branches and the stems has opened 2) On a regular basis as determined by the tree managers but I suggest every second month If the tree has props and a may -pole installed the inspection periods can be lengthened to bi-annual (twice per year) and after major storm events. Conclusion The lower limbs are likely to fail over the next five years. The risk associated with the tree is currently moderate but can be reduced with mitigation as described. It is my recommendation that the tree needs mechanical support if it is to be retained. ©Michael Richardson, B.Sc.F., BCMA, MTCU Qualified Arborist September 22, 2020 Red Oak, 21 Beech St., Bowmanville Page 22 of 27 Appendix A — Assumptions and Limiting Conditions The assessment of the tree(s) presented in this report has been made using accepted arboricultural techniques. When trees are inspected using Arbotom® Sonic Tomography, Resistograph®, or Arboradix®, results are for that location only and do not necessarily represent the state of the trees in non -probed areas. Notwithstanding the recommendations and conclusions made in this report, it must be recognized 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 weather conditions. While reasonable efforts have been made to ensure that the subject tree(s) are healthy, no guarantees are offered, or implied, that these tree(s) or any of their parts will remain standing. It is both professionally and practically impossible to predict with absolute certainty the behaviour of any single tree or its component parts under all circumstances. Inevitably, a standing tree will always pose some level of risk. Most trees have the potential for failure under adverse weather conditions, and the risk can only be eliminated if the tree is removed. This report is not intended as, and does not represent legal advice, and should not be relied upon to take the place of such advice. All photographs are reproductions that may vary from the original in size, clarity, tone etc. Original electronic images are stored by the Richardson Tree Care. Any copies of this report must be reproduced in colour or it is not valid. It is the responsibility of the tree owner to manage the trees. Not withstanding any recommendations made within the report, the consultant is not responsible for their implementation. ©Michael Richardson, B.Sc.F., BCMA, MTCU Qualified Arborist September 22, 2020 Red Oak, 21 Beech St., Bowmanville Page 23 of 27 Appendix B — Interpretation of Resistance Drilling Profiles Resistance drilling using the Rinntech R650-ED Resistograph® allows the determination of solid wood vs incipient decay and cracks or hollows. The machine measures the density of the wood and this is used to show a comparative chart of density vs. cross-section depth. Information is captured on an electronic chart and can be used to calculate the loss of LCC compared with an intact cross-section using ArboStAppTM. The horizontal axis represents drilling depth in centimeters and the vertical axis represents relative density of the wood encountered. po f ReH9ve 0.YbM1y ■Mtap C11%) Bart (t(5 Be°A) ©Michael Richardson, B.Sc.F., BCMA, MTCU Qualified Arborist September 22, 2020 Red Oak, 21 Beech St., Bowmanville Page 24 of 27 Appendix C — Interpretation of Sonic Tomography Images The Arbotom® is used in advanced tree risk assessments. By evaluating the condition of the wood quality in the entire cross section (the extent and configuration of internal decay), strength loss due to decay can be assessed. That data is then used to gain a better sense of what is happening to the tree and how that might affect the likelihood of failure component in a risk assessment. A series of sensors are placed around the tree trunk or limb, each one connected to the next and then to a computer. Each sensor is tapped, which sends a stress wave across the wood to the other sensors. When wood quality is high (solid wood no defect) the stress waves travel rapidly. When wood quality is low (decay present) the stress waves take longer to move through the wood, and if wood is missing (cavity, or crack) they have to travel around that area, thus taking a lot longer to reach other sensors. The data produced is called a tomogram, which provides a display of the stress wave travel times. Interpreting the tomogram allows the user to get a better sense of where decay might be present, as well as the type and extent of the decay. ©Michael Richardson, B.Sc.F., BCMA, MTCU Qualified Arborist September 22, 2020 Red Oak, 21 Beech St., Bowmanville Page 25 of 27 Project: Rochester Location: Above Head 2-5m Tree: Tree species: Quercus H: 2 cm i 50 cm i 1 16 ------ - �- - - 49 4 145 cm 7 i 8 0 9 Date: 2019-07-14 Interpreted speed is shown in the left bar with purple indicating hollows, red decayed, yellow incipient decay, and green intact wood. 120D 0 775 mis 350 ©Michael Richardson, B.Sc.F., BCMA, MTCU Qualified Arborist September 22, 2020 Red Oak, 21 Beech St., Bowmanville Page 26 of 27 Appendix D — Interpretation of Mechanical - Sonic Tomography Images The `mechanics -graph' shows two relative (0 to 100%) scaled curves of the moment of resistance of the cross section to bending by wind from different directions. The green curve is for the intact cross-section, and indicates how the cross -sectional shape of the local mechanical stresses adjusted (e.g. by wind). The red curve shows the relative resistance torque curve in the light of the tomogram graph and any possibly damaged state. The red arrow shows the direction of the "weakest" geometry and the associated number the maximum loss of load carrying capacity as compared with an intact cross- section of the same geometry. Project. Rochester Tree Date: 2019-07-14 Location: Above Head 2.5m Tree species: Quercus H: 2 cm 1200 ------- 775 F Geometric (87% - 100%} Current (91% - 97%) 350 ©Michael Richardson, B.Sc.F., BCMA, MTCU Qualified Arborist September 22, 2020 Red Oak, 21 Beech St., Bowmanville Page 27 of 27 Appendix E — Certificate of Performance I, Mr. Michael Richardson, do certify: • That I have personally inspected the plant material referred to in this report and have stated my finding(s) accurately. The extent of the evaluation is stated in the attached report; • That no one provided significant professional assistance to me, except as indicated in the report. Where observations and data have been collected by others this is stated; • 1 have no current interest in the vegetation or the properties that are the subject of this report • That the analysis, opinions, and conclusions stated herein are my own and are based on current scientific methods and facts; • That the analysis, opinions, and conclusions were developed and this report has been prepared according to commonly adopted arboricultural standards; • That my compensation is not contingent upon the reporting of a predetermined conclusion that favours the cause of the client or any other party nor upon results of the assessment, the attainment of stipulated results or the occurrence of any subsequent events; • 1 hereby certify that I am an Ontario 444A Arborist having complete the apprenticeship through the Ontario MTCU; • 1 have been involved in the field of arboriculture in a full time/part time capacity for a period of more than 25 years; Signed Date September 23, 2020 Michael Richardson, B.Sc.F., ISA BCMA ON-0377B Ontario MTCU Qualified Arborist Butternut Health Assessor # 472 ©Michael Richardson, B.Sc.F., BCMA, MTCU Qualified Arborist September 22, 2020 iY I - • - ...w, 79 . mil••"_ .� tS ..�a •.; �-3 .8 �Y -.1 .� rim" Richardson Tree Care P.O. Box 8. Brighton, Ontario KOK 1 HO April 19, 2021 Ken Mercer Supervisor Public Works Department Municipality of Clarington 40 Temperance Street, Bowmanville ON L1 C 3A6 905-623-3379 ext. 2945 KMercer(a-).clarington.net Re: Beech Street Oak Tree This pricing is a generalized guide for the retention of the oak tree at 21 Beech St., Bowmanville. It does not provide specific prices but rather provides a guide to understand the cost of retaining the tree using wooden utility poles. The assumption is that this methodology is acceptable but it is expected an engineer is needed to verify the size and suitability of various portions of the system. The subject tree is 186 cm diameter red oak on the front lawn/municipal road allowance at 21 Beech St. The tree is approximately 230 years old and can certainly live for another 50 years if cared for. The primary issue with the tree is the two lowest, over- extended, heavy limbs that are at risk of failure. Secondarily other limbs are at risk of failure. The primary mechanism for short term retention is to support limbs using a combination of utility poles supporting the limbs and cabling the limbs to the pole. Pruning of the tree shall be done to remove deadwood and reduce the size of the tree. It is hoped that new interior growth can be encouraged and the tree can be further reduced in the future. Morpho-physiological Age of Trees Young maturing phase: Early to late maturity: Early-, mid- & late -ancient Apical dominance Lower units break free from phases: crown retrenchment & apical dominance reiterative growth (a) F N (h) t) O 0 0 '�.J (2� Trees do not have a finite lifespan but rather are subject to the strains of their site and grow larger to an ultimate size then reduce in size and hollow. This is a fully natural process and we can hope to prolong the life of a tree, and manage risk, by reducing the size of the tree and supporting it where necessary. The tree is at approximately stage 7/8. The hope is to support the limbs, allow new interior growth and reduce the tree over the next 20 to 50 years. The largest limb over the road is to be supported by two poles. The shorter one will support the distal end while the taller pole will support the proximal end and be used to cable limbs to. P1 it i a 'Y]7Yb � I f yam' ''x . • bSaAC-.': ' - ... f FAin t'�af IL — ems_ - - - _ �-'.'�%'•. _ -7,�•' `Z' i_ ♦ '` �p, } fF ,r F`'�r £� � � • s � f � � � ���` �� � , � his,. ` b '"•� Sequence of steps 1) Decide on preservation path based on price, feasibility, risk management, homeowner, residents etc. 2) Design support system based on: a. Locates b. Engineering as required c. 21 Beech St homeowner agreement, ability to place poles d. Tree components to be supported 3) Prune Tree a. Remove all deadwood >5cm diameter b. Reduce limbs by 3-4 in length to allow sunlight to penetrate and encourage reiterations c. Tree pruning to be supervised by Michael Richardson to achieve goals of crown reduction and to initiate new interior growth d. Tree pruning to be done by a company that meets standards for pruning set by Michael Richardson (thus companies specializing in tree removal and utility line clearing may not be able to provide proof of pruning knowledge and experience required) 4) Locate Poles on site 5) Hydrovac holes a. Hydrovac company shall be chosen by pole install company b. Water pressure shall be reduced to avoid damage to roots c. Hydrovac shall be supervised by Michael Richardson 6) Install poles a. A utility company will do this b. Pole installation shall be supervised by Michael Richardson 7) Install cross braces if needed a. Pole installation company can do this 8) Install cabling a. Cable limbs to pole using approved hardware b. Cabling shall be supervised by Michael Richardson 9) Soil invigoration a. Reduce soil compaction and introduce fish fertilizer into soil b. Develop prescription to encourage reintroduction of organic matter into soil. c. Mulch boulevard with wood chips 10) Yearly monitoring 11) Further pruning, likely year 8--10 Generalized costs These costs have been estimated by talking to suppliers and contractors. Prices are estimates only and will change based upon the specifics. In particular the costs of engineering, poles, and cabling hardware will be determined once a formalized plan is developed. Design of support System, create detailed pruning specifications, gather quotes etc. (Michael Richardson) $1500 Engineering of Support System $5000? Deadwood & Pruning $3000 Supervision of Pruning (Michael Richardson) $800 Poles 2-75 H1 poles $8500/pole 1-30 $2500 1-25 $2500 $23000 Hydrovac $3500 Supervision of Hydrovac (Michael Richardson) $500 Pole Install $3500 Supervision of Pole Install (Michael Richardson) $800 Cabling Equipment $7500 (likely high) Cabling labour 4000 Supervision of Cabling (Michael Richardson) 1000 Soil invigoration — can be delayed 2000 Locates Free? Specific Costs If you wish to proceed, we can begin the process of developing a specific plan, quantifying materials and obtaining quotes. Signed Michael Richardson, B.Sc.F., ISA BCMA ON-0377B Ontario MTCU Qualified Arborist Butternut Health Assessor # 472