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HomeMy WebLinkAbout10/23/2023 Item 4a, AlvarezRisk is the combination of the likelihood of an event and the severity of the potential consequences. In the context of trees, risk is the likelihood of a tree failure occurring and affecting a targetz. This assessment is a limited assessment of the tree and its surrounding site, and synthesis of the information collected. It is important to understand that a basic assessment is a visual assessment whose primary limitation is that it includes only conditions that are visually detected from the ground. Internal, below ground, and upper crown factors maybe impossible to see or difficult to assess and may remain largely undetected. The risk assessment describes the potential target identified, the part of the tree most likely to fail, and the consequences of the failure. Recommendations are made that can reduce the failure potential, or the consequences of the failure. However, the recommendations cannot eliminate all risk. Any tree left in place will still have some residual risk, to the specified target or to another target. This risk assessment is based upon the specific time frame of 1 year. The specified time frame is NOT a guarantee. This is due in part to possible changes that could occur in the environment around the tree, or in the tree itself. For instance, strong wind storms may place a heavy enough load on a tree to cause immediate failure, or create hidden cracks that could lead to a failure prior to the end of the inspection interval. BACKGROUND INFORMATION REGARDING RISK ASSESSMENTS Most tree failures occur during winter storms, although an occasional tree that is heavy with foliage or seeds or under extreme heat stress can fail in summer months, often unexpectedly. Such failures cannot be accurately predicted. However, the potential for trees with known defects to fail can be assessed and viewed based upon potential consequences. This is the purpose of risk assessment - to guide the property manager in choosing mitigation options once the risk inherent in the assessed trees is understood. Tree Risk Assessment is the current Best Management Practice of the industry. It is a systematic process to identify, analyze, and evaluate tree risk, that has been established by the International Society of Arboriculture. Risk is the combination of the likelihood of an event and the severity of the potential consequences. In the context of trees, risk is the likelihood of a conflict or tree failure occurring and affecting a target. Risk assessment focuses on the potential structural failure of the trees assessed and their surrounding site, and synthesis of the information collected. It is important to understand that a basic assessment is a visual assessment. The primary limitation is that it includes only conditions that are visually detected Z A Target is a person, building or other property that may be injured or damaged by a tree or tree part. s Lilly, Sharon and Rachel Liebowitz, Editors. 2011. Tree Risk Assessment: Best Management Practices. International Society of Arboriculture. Champaign, Ill. Pages 7-15. A&I Arborists and Vegetation Management Page 2 of 6 from the ground; internal, below ground, and upper crown factors may be impossible to see or difficult to assess and may remain largely undetected. A risk assessment looks at and analyzes the following: 1. Likelihood of Impact to a Target (Very Low, Low, Medium, High) 2. Likelihood of Tree Failure (Improbable, Possible, Probable, Imminent) 3. Likelihood of Failure Impacting Target: (Unlikely. Somewhat Likely Likely Very Likely) 4. Consequences of the failure on the Target (Negligible, Minor, Significant Severe) 5. Risk Rating: (Low. Moderate. High, Extreme) The risk assessment will therefore describe the potential target identified, the part of the tree most likely to fail, and the consequences of the failure. Recommendations will be made to reduce the failure potential, or the consequences of the failure. However, most of the time, the recommendations will not eliminate all risk. Any tree left in place will still have some residual risk, to the specified target or to another target. OBSERVATIONS Site and Target Description 1440 Higuera street slo ca 93401 Target: garage, parking stalls, utility lines Tree Condition Upper canopy limbs have failed recently, they are likely to fail in the future. The massive sprouts at the trunk base is increasing the tree to out grow its growing area. CONCLUSIONS Parts of the tree most likely to fail: 1. Heavy horizontal limbs over the garage as well as the parking and utility lines: Probable 2. The trees roots and sprouts could lift the garage floor, walls, and hardscape: Probable Likelihood of Impact: The potentials failure(s) listed above would have a high probability of hitting a valuable target, with significant to severe consequences. Risk Rating High A&T Arborists and Vegetation Management Page 3 of 6 7/10/2n23 REcoMMENDATIoNS Report Prepared by: Steven Alvarez CERTIFIED ARBARIST #WE-0511A APPENwas: APPENDIX 1-- MAP OF THE SITE, WITH TREE LOCATION APPENDIX 2 — RISK ASSESSMENT RATING FoRm A&T Arborists and Vegetation Management Page 4 of 6 APPENDIX 1— MAP OF TREE LOCATION N\��V�C-A A&T Arborists and Vegetation Management i \ act. Page 5 of 6 l� Basic Tree Risk Assessment Form Client - - Date .-;Z - Time Jzz,,� h� Address/Tree location r © �'' Fig Tree no. �_ Sheet of Y_ Tree species dbh� Height ` Crown spread dia. Assessor(s) S/ e-y e h az l2cmz Tools used Time frame «; �f0 Target Assessment SO4N�•.Vc {92�./ `v Target zone a Occupancy 01 c e e c Target description Target protection ; = 3 '� $ �a-G 9 V _4 z-owreslonal 3—frequent Fq f f 4—constant 6 E C 6 2 3 4 Site History of failures Se ✓u4 I Lj pp e.-r 0 k e_ f4� Topography Flat)d Slope2� '2 4 % Aspect-Aa Site changes None Grade change%Site clearirdO Changed soil hydrology❑ Rootcuts[] Describe Soilconditions Limited volumelA Saturated ❑ Shallow8f Compacted❑ Pavement overrootsRl 5TC7 % Describe Prevailing wind direction V Common weather Strong winds ❑ Ice ❑ Snow❑Heavyrain❑ Describe o.- {� Tree Health and Species Profile Vigor Low Normal High❑ Foliage None(seasonal)❑ None(dead)❑ Normal% Chlorotic_% Necrotic_% Pests/Biotic �e �yhsas�� Abiotic L'ti Species failure profile Branches OL Trunk ❑ Roots❑ Describe4ippu- is-wrhe Wind exposure Protected Partial Full. Windfunneling63.. Relative crown size Small❑ Medium❑ Large Crown density Sparse ❑ Normal ❑ Dense ❑ Interior branches Few❑ Normal ❑ Dense❑ Vines/Mistletoe/Moss❑ Recent or expected change in load factors r z— S C r /.i o ruv vvr e t Tree Defects and Conditions Affecting the Likelihood of Failure —Crown and Branches — Unbalanced crown a. LCR-LQ% Cracks U Lightning damage❑ Dead twigs/branches ❑ _'L%overall Max. dia. 6 Codominant IN ve—S q o p Included bark ❑ Broken/Hangers Number O Max. dia. O Weak attachments ❑ NOnI Cavity/Nesthole 0 %circ. Overextended branches ❑ Previous branchfailures'A Similar branches present PL Pruning history Dead/Missing bark Cankers/Gall url ❑ Sapwood damage/decay❑ Crown cleaned ❑ Thinned ❑ Raised Reduced IR Topped ❑ Ilrton-tailed ❑ Conks ❑ Heartwood decay ❑ Flush cuts ❑ Other L �• wL %s a fir dar_e V ( Response growth r se g _ �—o tJ__- l: r E's%r�so �roM Condition (s) of concern Tp y 0-040 t V�hah�7 e �.�.e_ r't ✓'rpirof-C.: cr,rnc.J-� yty.11 Qt l.Pf- i:r�v� .5; Fi- ri,r.G Part Size l^�'— R Fall Distance 6010 Pa rtPart Siz Fall Distance Load on defect N/A❑ Minor ❑ Moderate❑ Significantik Load on defect N/A❑ Minor ❑ Moderate❑ Significant, Likelihood of failure Improbable❑ Possible Probable K,imminent ❑ Likelihood of failure Improbable❑ Possible Probable Imminent El runk ots and Root Collar Dead/Missing bark ❑ Abnormal bark texture/color ❑ Collar buried/Not visible ❑ Depth Stem girdling ❑ Codominant stems ❑ Included bark Cracks ❑ Dead ❑ Decay ❑ Conks/Mushrooms ❑ Sapwood damage/decay ❑ Cankers/Galls Burl W Sap ooze ❑ Ooze ❑ Cavity ❑ _%cirt. Lightningdamage❑ Heartwood decay Conks/Mushrooms❑ Cracks Cut/Damaged roots Distance from trunk Cavity/Nest hole _ %circ. Depth Poor taper ❑ Root plate lifting),11 Soil weakness ❑ Lean_. Corrected? Response growth rD Response growth Response Condition(s) ofconcern u4P_r k,.:Condic•�,up r: to/a SP L- 4s -40 04 - gr•vw Part Size Fall Distance Part Size 4 -- ram— Fall Distance Load on defect N/A❑ Minor ❑ Moderate❑ Significant❑ Load on defect N/A❑ Minor ❑ Moderate❑ Significantik Likelihood of failure Improbable❑ Possible Probable imminent Likelihood of failure improbable El Possible Probable %"Imminent❑ Risk Categorization Target (Target number or description) Tree part Condition(s) ofconcern Likelihood Consequences Risk rating Matrix 2) Failure Impact Failure & Impact (from Matrix l) m a Q w a a a a 3 j 'x > t ,°n S j a Z G h LL {., To ir--1 .6 f- (:10-,f � -"-L a -/4 V/ I C�� LAP 0,.40 c C1 Matrix/. Likelihood matrix. Likelihood of Failure Likelihood of Impact Very low Low Me ' m High Imminent Unlikely Somewhat likely Likely Ve likely Probable Unlikely Unlikely Somew at likely Likely Possible Unlikely Unlikely Unlikely omew at likely Improbable Unlikely Unlikely Unlikely Unlikely Matrix 2. Risk rating matrix. Likelihood of Failure & Impact Consequences of Failure Negligible Minor ignificant severe Very likely Low Moderate ig Extreme Likely Low Moderate Hig High Somewhat likely Low Low Moderate Moderate Unlikely Low Low Low Low Notes, explanations, B i Notth Residual risk - Residual risk _D 3. /1' [' ci �cir v � ,✓ u r • /1 Residual risk 4. _._ Residual risk Overall tree risk rating Low ❑ Moderate ❑ High Z Extreme ❑ Overall residual risk None ❑ Low ❑ Moderate ❑ High i)i Extreme ❑ Recommended inspection interval Data OFinal 0Preliminary Advanced assessment needed VNo OYes-Type/Reason Inspection limitations ONone OVisibility OAccess Pvines gRoot collar buried Describe This datwheet was produced by the International Society of Arboriculture (ISA) — 2017 Page 2 of 2 Pry wlar7 3/ K ✓O// /1, IT%Ls Secbn �a ✓ aGfa Jc e l.' cat $'Csi'yi ors St Gul fow� s.^� Co lvi !.�4Ii Gc �i Oa ver /K62n j e u3 fc i.+oi s / Ibtr'2Q 4t� Eo� �i42��-C� .su 6 cc-f 1 r - - v85Tall I -ass cr�� 5 m a5s;dL. 6U rf 6 uj 4r bQ,.J G1 1; 7C-,i-'9 F�a� rev-l-s po,k vi S Poc----a, a, x6,3- 5 6.ro�,-�i C4 r h cr- CA< ifl curd G fP 3 bt)Yr%j;(.-w Lu �-cw;N� 4f JNows tfd"�:.rq GF�� —TO� wvl � r ,, /, 2 ic?c� f&55-Tv-c- pte>4S aKV G�efs — 7-�'S w-/l 4-e m r brl,- U;-e-w vF sa--,�:rf cIe�.Ti� s �-ri- 7