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Arborist Report Addendum 3-6-20Addendum To: Jacob Strobl Company: Strobl Design From: Benjamin Mark — American Forest Management CC: Date: 3/6/2020 Re: Proposed work near tree #106 at 9527 190th Place SW- Edmonds, WA Greetings, AMERICAN FOREST MANAGEMENT APPROVED BY PLANNING 11h7- e` D Mar 23 1U2U Per your request, On March 4, 2020, 1 evaluated the recent excavation near the root system of a tree identified in an arborist report I prepared on April 17th, 2019 as #106. The subject tree is a Douglas fir with a dripline to the south of 18 feet, 12 feet to the east, and 14 feet to the west. The dripline extends over the property line to the north. Prior to construction, this tree was surrounded by several mature Douglas fir trees to the west, south and east which have since been removed. The original arborist report recommended a limit of disturbance to the roots of Tree #106 no closer than 15 feet to the south. I visited the site to assess the subject tree's condition following excavation to the south for a concrete foundation. I found the grade 6 feet south of Tree #106 lowered by approximately 4 feet. Several large structural roots were found cleanly cut at the face of the newly excavated slope. Seven cut roots over 2 inches were documented. These range in diameter from 3 to 7 inches. A very large surface root at least 12 inches in diameter extends to the north and appears unaffected by the recent work. The cut roots represent a significant defect directly impacting the stability of this tree. Using the International Society of Arboriculture (ISA) Basic Tree Risk Assessment method, I determined the risk currently presented by this tree under normal weather conditions over a two year time frame to be HIGH. This assessment is made subject to Level 2 TRAQ assessment guidelines and best management practices and represents my observations on the day of the inspection. I used the ISA Basic Tree Risk Assessment method and assessed this tree for risk of branch or trunk failure. I determined the primary target in the event of failure to be the neighboring j 1� ,l'S �'9 lJl,D-2,,--� V q' 0 11415 NE 128fh St., Suite 110, Kirkland, WA 98034 1 Phone: 425.820.3420 1 Fax: 425.820.3437 1 americanforestr_nppogemtl#soj=`i^ Memo —9527 190th Place SW, Edmonds WA house to the north due to the prevalence of winds from the south west in this area, and all of the roots on the south side of this tree being severed. I determined the likelihood of whole tree failure to be probable under normal weather conditions in a two year time frame. I also determined the likelihood of the tree striking the target in the event of failure. Following these conclusions, I assigned the following rating: TREE#106 WHOLE TREE failure within the following two years is PROBABLE, with a HIGH likelihood of striking the neighboring house. It is LIKELY the probability of failure and impact would result in SEVERE consequences such as damage to high value property, serious injury or fatality, or major disruptions. Following the ISA TRAQ Risk Categorization Matrix, this tree presents a HIGH risk. Recommendations • Adhere to City of Edmonds City Code 18.45.050 — Performance Standards for Land Development Permits. • Consult with your City Planner to determine options to expedite removal of this High Risk tree. • Obtain all necessary permits from the City of Edmonds before carrying out removal of this tree. There is no warranty suggested for any of the trees subject to this report. Weather, latent tree conditions, and future man -caused activities could cause physiologic changes and deteriorating tree condition. Over time, deteriorating tree conditions may appear and there may be conditions, which are not now visible which, could cause tree failure. This report or the verbal comments made at the site in no way warrant the structural stability or long term condition of any tree, but represent my opinion based on the observations made. Nearly all trees in any condition standing within reach of improvements or human use areas represent hazards that could lead to damage or injury. Please call if you have any questions or need further assistance on this project. Sincerely, Benjamin Mark ISA Certified Arborist #PN-6976A ISA Tree Risk Assessment Qualified American Forest Management, Inc. March 5, 2020 r ti 40 40. • *.tr `i AI�K�y,�:. . ♦ I 7r , � R� �• fit+., Memo —9527 190th Place SW, Edmonds WA Looking down at the face of the excavated slope and recently assembled concrete fnnn for the foundation. Note the largest root cut is at the surface and is approximately 6 feet from the trunk of#106. American Forest Management, Inc. March 5, 2020 AMERICAN FOREST MANAGEMENT Date: 3.42020 4 Inspector: Benjamin Mark TREE RISK ASSESSMENT SUMMARY Site: 9527 190th Place SW Edmonds, WA 98020 DBH Height Tree ff species (inches) (feet) Location Defects Failure Impact Con Rocommrndation Recent excavation and all roots cut 6 On slope near north feet south of this tree. Newly 106 Douglas fir 39 115 property line. exposed interior tree. Probable High Severe High Remove Likelihood of Failure Imminent - started or likely in near future Probable - expected in normal weather conditions Possible - could occur, but unlikely in normal weather conditions Improbable - not likely in most weather conditions Likelihood of Impact Very Low - remote, protected target, rarely used Low - not likely, protected target, occasionally used area Medium - 50/50 chance of impacting target High - most likely, fully exposed target, constant occupancy Likelihood of failure Likelihood of Impacting Tar, t VeryLow Medium High Imminent Unlikely Somewhatlikelyl Likely Very like) Probable Unlikely Unlike lv Somewhat LikelyLikely Possible UnlikelyUnlikel Unlikelv Somewhat Likelv Im obabie Unlikely Unlikelv Unlikely Unlikely Consequences of Failure Negligible - no injury, repaired or replaced, low -value Minor - moderate property damage, minor injury, small disruptions Significant- high property damage, considerable disruption or personal injury Severe - damage to high value property, serious injury or fatality, major disruption Likelihood of failure & Impact Consequences of Failure Neglialble Minor Si nificant I Severe Very likely Low Moderate High Extreme Likely Low Moderate High High Somewhat likely Low Low Moderate Moderate Unlikely Law Low Low Low Low - mitigation may be appropriate, lower work priority Moderate - mitigation and/or retention and monitoring High - mitigation measures must be taken Extreme - mitigation measures as soon as possible � may- � ��', r •�. .�. �• .. •'A� ebb • ` C �.�. , .% � ,I � s, _ ��t}' ;t � �ti April 171h, 2079 Page 1 Table of Contents 1. Introduction...................................................................................................................................................... 2 2. Description.......................................................................................................................................................2 3. Methodology...................................................................................................................................................2 4. Observations................................................................................................................................................... 3 5. Discussion..........................................................................................................................................................4 6. Tree Protection Measures...................................................................................4 Appendix Site/Tree Photos — pages 6-7 Tree Summary Table - attached Tree Conditions/Tree Plan Map AMERICAN FOREST MANAGEMENT, INC. April 171h, 2079 Page 2 1. Introduction American Forest Management was contacted by Jacob Strobl, architect at Strobl Design and asked to compile an arborist report for a parcel located within the City of Edmonds. The proposed development encompasses Snohomish County Parcel #00434600007901. Our assignment is to prepare a written report on present tree conditions, which is to be filed with the preliminary permit application. This report encompasses all of the criteria set forth under the City of Edmonds tree regulations (Chapter 18.45 of the Edmonds Community Development Code - ECDC). Dateof Field Examination: .................................................................................................... April 12, 2019 2. Description Fifteen significant trees with a caliper 6 inches or greater 4 feet above grade (or diameter at breast height - DBH) were located and assessed on the property. None of these trees are considered non- viable due to poor health condition, however there are two standing dead snags in this grove. Additionally, two neighboring trees with driplines that extend over the property line were also assessed for potential impacts from the proposed development. Every tree included in this report was identified in the field with a numbered aluminum tag. These tag numbers correspond with the attached Tree Summary Table and Tree Map. Several trees were found which did not appear on the original survey. These were added on the attached Tree Summary Table and their approximate location added to the Tree Map. Their actual location should be verified in an updated survey. The tree summary table provides descriptive data for all assessed trees, including drip -line measurements. 3. Methodology Each tree in this report was visited. Tree diameters were measured by tape. This required removing some ivy from each tree to get an accurate measurement. The tree heights were measured using a digital clinometer. Each tree was visually examined for defects and vigor. The tree assessment procedure involves the examination of many factors: • The crown of the tree is examined for current vigor. This is comprised of inspecting the crown (foliage, buds and branches) for color, density, form, and annual shoot growth, limb dieback and disease. The percentage of live crown is estimated for coniferous species only and scored appropriately. • The bole or main stem of the tree is inspected for decay, which includes cavities, wounds, fruiting bodies of decay (conks or mushrooms), seams, insects, bleeding, callus development, broken or dead tops, structural defects and unnatural leans. Structural defects include crooks, forks with V-shaped crotches, multiple attachments, and excessive sweep. • The root collar and roots are inspected for the presence of decay, insects and/or damage, as well as if they have been injured, undermined or exposed, or original grade has been altered. Based on these factors a determination of viability is made. Trees considered 'non -viable' are trees that are in poor condition due to disease, extensive decay and/or cumulative structural defects, which exacerbate failure potential. A 'viable' tree is a tree found to be in good health, in a sound condition AMERICAN FOREST MANAGEMENT, INC. April 7 7'h, 2079 Page 3 with minimal defects and is suitable for its location. Also, it will be wind firm if isolated or left as part of a grouping or grove of trees. The four condition categories are described below: Excellent — free of structural defects, no disease or pest problems, no root issues, excellent structure/form with uniform crown or canopy, foliage of normal color and density, above average vigor, it will be wind firm if isolated, suitable for its location Good — free of significant structural defects, no disease concerns, minor pest issues, no significant root issues, good structure/form with uniform crown or canopy, foliage of normal color and density, average or normal vigor, will be wind firm if isolated or left as part of a grouping or grove of trees, suitable for its location Fair — minor to moderate structural defects not expected to contribute to a failure in the near future, no disease concerns, moderate pest issues, no significant root issues, asymmetric or unbalanced crown or canopy, average or normal vigor, foliage of normal color, moderate foliage density, will be wind firm if left as part of a grouping or grove of trees, cannot be isolated, suitable for its location Poor — major structural defects expected to cause fail in the near future, disease or significant pest concerns, decline due to old age, significant root issues, asymmetric or unbalanced crown or canopy, sparse or abnormally small foliage, poor vigor, and/or not suitable for its location The attached Tree Summary Table provides specific information on tree sizes and drip -line measurements. 4. Observations Most of the subject parcel was covered in dense mats of English ivy which is climbing into the canopy of the majority of the trees included in this report. Twelve of the 15 significant trees found here are Douglas fir (Pseudotsuga menziesii) all but two of which are in good condition, the others are in fair condition. These range in caliper from 15"-44". Most are on the larger end of this range with an average caliper of 35.75" Trees #101-107 are Douglas fir situated near the northern edge of the subject property. Most of these form a grove of contiguous canopy cover which includes trees north of the property line. There are two standing dead snags in this grove. Trees #101 and #106 are the only trees able to be retained in the proposed site plan due to the necessary excavation cut on the hillside. There are likely large structural roots on this slope which would be destroyed at the planned grade. Trees #108-1 1 2 are Douglas fir in the center of the parcel. All of these will need to be removed for the proposed structure to fit within the front yard setback. Limits of disturbance are shown for some trees which are proposed for removal in case revised plans include their retention. Other species present are red alder (Alnus rubra), big leaf maple (Acer macrophyllum), and bitter cherry (Prunus emarginata). These are all located along the raised grade within the proposed building footprint. These are considered 'pioneer species' trees which are often the first to naturally germinate in open areas. These are fast growing when young, and quickly reach maturity. Their branch strength is rated as weak. A typical characteristic of these trees upon reaching maturity is to shed limbs as they become host to decaying fungi and eventually fall from primary stem failure. AMERICAN FOREST MANAGEMENT, INC. April 171h, 2019 Page 4 Neighboring Trees with Overhanging Canopies Tree #201 is an apple (Malus sp.) with two primary stems for a calculated 8" DBH which has been regularly pruned to maintain a height of 12'. This tree is part of a small orchard in the southwest corner of the neighboring property. Its canopy extends approximately 12' over the east property line. This tree is below the existing driveway grade 6' to the west. #202 is a Douglas fir with a DBH of 14" growing just north of the property line in a grove which includes trees #101-107. It is in fair condition with a thin canopy as a result of being dominated by the larger trees nearby. 5. Discussion/Recommendations Due to lack of existing targets, no high -risk tree conditions were observed at the site. All subject trees would be rated as low to moderate risk under an ISA Level II Basic Assessment, however this assessment is a limited by the extent of ivy coverage on their lower trunks. A reassessment upon final building and grading plans would be prudent. Given the proposed site plan, few of the trees found on the property are able to be retained. These trees are primarily Douglas fir and will help maintain a buffer to the property to the north. The neighboring trees to the north are not likely to sustain damage related to construction if all work performed remains outside of their Limits of Disturbance (LOD). The ground to the south of them on the subject property is sloped and there are several large trees which are not able to be retained (#102, #103, #104, and #105) due to the excavation cut to meet planned grade. Neighboring tree #202 is located at the top of the slope and is dominated by the larger trees to the south. This has led it to developing a thin canopy and likely a relatively small structural root system due to the larger trees sheltering it from prevailing winds. Removing these trees, particularly #105 will open up tree #202 to more severe exposure than it has previously received. The extent of drip -lines (farthest reaching branches) for the subject trees to be retained can be found on the tree summary table at the back of this report. The recommended LOD measurements can also be found on the tree summary table. The LOD measurements are based on species, age, condition, drip -line, and prior improvements. These shall be referenced when determining the feasibility of retention. 6. Tree Protection Measures The following general guidelines are recommended to ensure that the designated areas set aside for the preserved trees are protected and construction impacts are kept to a minimum. Tree protection should adhere to best management practices for tree and soil protection during development activity. 1. Tree protection fencing shall be erected around retained trees and positioned just beyond the drip - line edge prior to moving any heavy equipment on site. Doing this will set clearing limits and avoid compaction of soils within root zones of retained trees. 2. Any existing improvements to be removed within the drip -lines or tree protection zones shall be removed by hand or utilizing a tracked mini -excavator. 3. Excavation limits should be laid out in paint on the ground to avoid over excavating. AMERICAN FOREST MANAGEMENT, INC. April 171h, 2079 Page 6 Photos #108 #109 #106 #110 #111 #112 AMERICAN FOREST MANAGEMENT, INC. Note ivy on stems F/• , .'// �)�iy�Fc' t .mot . �'. ! �T "i;':�!t :� � Y a �' �• � .. F* i.l ,'.a,y�r�piy j/•/� •�i�;y.l�, r, ...} .� •�•%"y-Y `:•Tr'--, Z�Tr:V;.1:,f •. i•,� `. � w••••yI _,,,. � , trl�,'4Y��.e:• .: �•�', (Tree Summary Table ! !American Forest Management, Inc. 'For: 19527 190th PI SW Edmonds WA Date: 4/11/2019 Inspector: Ben Mark I iTaci# , ID Genus species DBH inches Height feet Drip -Line / Limit of Disturbance feet Condition Viable I yes/no Proposal Comments I N S E W 101 Douglas Fir Pseudotsuga menziesii 37 107 21 14 Good Yes Retain Trunk touches utiliUy lines. Ivy. Limbed up @ 30' and thin above 102 Douglas Fir Pseudotsuga menziesii 15 85 12 14 6 Good Yes Remove Added to map 103 Douglas Fir Pseudotsuga menziesii 27 95 16 14 10 Good Yes Remove Next to snag 104 Douglas Fir Pseudotsuga menziesii 34 110 24 19 22 Good Yes Remove 105 Douglas Fir Pseudotsuga menziesii 36 105 14 19 22 / 15 Good Yes Remove No canopy north 106 Douglas Fir Pseudotsuga menziesii 39 115 18 / 15 12 14 Fair Yes Retain Possible decay present in main stem. Added to map 107 Douglas Fir Pseudotsuga menziesii 41 97 15 16 22 / 16 Good Yes Remove Good taper 108 Douglas Fir Pseudotsuga menziesii 39 64 28 18 25 Fair Yes Remove Broken at 38' 109 Douglas Fir Pseudotsuga menziesii 44 118 20 12 20 Good Yes Remove Stout taper. Added to map 110 Douglas Fir Pseudotsuga menziesii 38 120 26 / 15 6 19 Good Yes Remove Dense ivy on south side. Just south of dead Douglas Fir 111 Douglas Fir Pseudotsuga menziesii 35 117 25 / 15 15 Good Yes Remove 112 Douglas Fir Pseudotsuga menziesii 44 105 16 16 16 Fair Yes Remove Broken at 39'. New leader and lesser codominant. Added to map 113 Alder Alnus rubra 14 51 16 16 20 12 Fair Yes Remove Leans east. Added to map. 114 Bitter Cherry Prunus emarginata 11 48 6 10 7 11 Fair Yes Remove Broken top. Added to map 115 Big Leaf Maple Acermacrophyllum 20 61 12 16 14 14 Fair Yes Remove lAdded to map Nailghbof Trees 201 jApple Malus sp 5.6 12 12/6 Good Yes 202 Douglas Fir Pseudotsuga menziesii 14 Fair Yes Leans west . thin crown Drip -Line and Limits of Disturbance measurements from face of trunk I !Trees on neighboring ro erties - Drip -line and Limits of Disturbance measurements from property lines Calculated DBH for multistem trees: The DBH in BOLD is the square root of the sum of the DBH of each individual stem, squared. Example 3 stem DBH = Square Root stem! 2 + stem2 2 + stem3 2