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HomeMy WebLinkAboutAttachment C_Arborist ReportR i p p e y A r b o r i c u l t u r e L L C C H I L D T r e e I n v e n t o r y J a n u a r y 5 th, 2 0 2 1 P a g e | 1 Arboreal Report Date: January 5th, 2021 To: Carrie Fannin, Executive Director Children’s Institute for Learning Differences (CHILD) From: Chris Rippey, Rippey Arboriculture LLC Subject: Result of a tree risk survey Introduction This report is the summary of an October 9th, 2020 tree inventory at 2640 Benson Road South in Renton, Washington. This survey was performed to address a City of Renton requirement that a tree risk survey must be performed every two years. My scope of work was to: • Inspect all trees at Children’s Institute for Learning Differences at 2640 Benson Road South in Renton, Washington. • Using a two-year timeframe, identify any tree or tree part that is likely to fail and impact the zipline area, wooded trail, parking lot, playground, driveway, school buildings or school walkways. • Attach an identification tag to each identified tree that meets the before mentioned categorization. • Offer care recommendations for each identified tree. Limitations and Assumptions The site and tree assessments were performed on the subject property only. All tree assessments were performed from the ground only, no aerial or below soil level investigation techniques were used. No advanced assessment tools including resistance drilling, sonic tomography imaging or ground penetrating radar were used. Any information provided was assumed to be true. All trees will eventually fail. Tree failures are the result of a combination of factors. Predicting precisely when or how trees will fail is not possible. Unless fully removed, all trees pose some amount of risk to humans. My assessments and care recommendations do not consider targets or the occupancy rates of targets which the assessed trees could damage. These recommendations do not consider the risk tolerances of the tree owner. Tree assessments and recommendations are not meant to be relied upon as fact or promises of a result. These assessments and care recommendations are only considerations for the tree owner’s decision-making process. The tree owner, and not Rippey Arboriculture LLC is responsible and potentially liable for the assessed tree and damages that it may cause. Site Assessment The subject property is a 4.01-acre parcel on the southern tip of east side of Renton. This parcel on a western facing slope. The southern half of the property is developed with the school, a playground, and parking lot. The northern half of the property is relatively undeveloped with a zipline and a trail through a wooded area. Tree Assessment The trees on this site are a mixture of Pacific Northwest native trees. The dominant tree on the site is big leaf maple (Acer macrophyllum). The next most observed tree was black cottonwood (Populus trichocarpa), followed by red alder (Alnus rubra). Most of the trees on the property were declining in health or dead. There are few trees in good health. Most trees of this site declining in health or being dead is due to several factors including the trees having limited access to water due their location on slopes and the presence of aggressive understory plants like grass, blackberry and ivy taking up much of the rainwater. There are also several possible biotic disorders affecting the trees on the site. These include the parasitic fungal infections of Kretzchmaria duesta, Ganoderma sp., and Cryptostroma corticale. The identifications of these organisms are based on my R i p p e y A r b o r i c u l t u r e L L C C H I L D T r e e I n v e n t o r y J a n u a r y 5 th, 2 0 2 1 P a g e | 2 22-year experience in identifying wood decay causing fungus. The presence of both organisms is concerning but is not unexpected. These organisms are common to our area and well known to cause death or tree failure in infected trees. Both organisms are untreatable but infected trees should be removed as soon as possible to reduce fungal spore presences and slow the spread of these organisms throughout the site. The timing of removing sooty bark disease infected trees is particularly important because the spores produced by the organism by the organism can infect humans with respiratory infections. To limit this hazard to users of the area, trees should be removed in winter during wet weather but not cold dry weather as this is when spores are most active. December is usually the best time to schedule work of trees infected with this disease. Site Assessment Results My site assessment has identified 24 trees that are likely fail within the next two years and impact the specified areas. Nine of these trees (1808, 1856, 1853, 1814, 1684, 1776, 1775, 1774 and 1755) are along the nature trail used by children of the school. These trees are all dead and can impact the trail and strike trail users when they fall. These trees should all be removed, or if safe to climb, reduced to wildlife habitat snags of a height no taller that the distance of the tree to the trail. Tree 1687 is in the natural area and is leaning towards the adjacent property. This tree needs to be removed because it is extensively decayed and will impact the adjacent property and apartment homes when it fails. There are six trees (1888, 1872, 1868, 1869, 1807, 1906, and 1889) located near a zipline area that is frequently used by children at the school. Three of these trees will be removed because they are dead and when they fail, they will likely impact the zipline area and could impact any users of that area. All other trees have large dead branches over hanging the area that must be removed before they fall on the zipline or the children using the zipline area. Tree 2495 is located on the school grounds. This tree is extensively decayed and is adjacent to a school walkway. When it fails, this tree will fail onto this frequently used walkway and can injure anyone using the walkway. All other trees (2022, 2613, 1978, 1977, 1976. 1926 and 1994) are dead or severely declining in health. These trees are all tree species that will start to shed dead branches soon after dying. These trees should all be removed because they are all adjacent to the parking lot and these dead branches or whole dead trees will impact the parking lot, users or the parking lot or cars in the parking lot when they fail. Specific recommendations for each identified tree can be found in the following Tree Inventory section of this report. Christopher Rippey Rippey Arboriculture, LLC PNW-ISA 2019, Arborist of the Year ASCA Registered Consulting Arborist #633 ASCA Tree and Plant Appraisal Qualified ISA Certified Arborist (WE-7672AUTM) ISA Tree Risk Assessor Qualified R i p p e y A r b o r i c u l t u r e L L C C H I L D T r e e I n v e n t o r y J a n u a r y 5 th, 2 0 2 1 P a g e | 3 Tree Inventory Tree ID Tree Species DBH Height Condition Present Decay Organism Work Notes and target 1888 Big leaf Maple (Acer macrophyllum) 68 80 Declining Kretzchmaria duesta (aggressive root decay organism) Pruning: remove upper portion of eastmost trunk. 5 trunks. Dead trunk will impact zipline when it fails 1872 Big leaf Maple (Acer macrophyllum) 17 80 Declining Kretzchmaria duesta(aggressive root and trunk decay organism) Remove Decayed at base. Will impact zipline when it fails. 1869 Big leaf Maple (Acer macrophyllum) 36 85 Declining Kretzchmaria duesta(aggressive root and trunk decay organism) Pruning: remove dead branch over zipline. 2 large parent branches at 5’. Dead branch will impact zipline when it fails. 1807 Big leaf Maple (Acer macrophyllum) 35 50 Dead Remove Tree will fail onto zipline area when it fails. 1868 Big leaf Maple (Acer macrophyllum) 6 20 Dead Remove Tree will fail onto zipline area when it fails. 1906 Big leaf Maple (Acer macrophyllum) 14 50 Dead Remove Tree will fail onto zipline area when it fails. 1889 Big leaf Maple (Acer macrophyllum) 126 80 Declining Sooty bark disease (can cause respiratory infection in humans) and Kretzchmaria duesta (aggressive root and trunk decay organism), sooty bark disease (can cause respiratory Pruning: remove 3 trunks, remove any dead wood over 4” diameter Dead tree branches will impact zipline area or driveway when they fail. R i p p e y A r b o r i c u l t u r e L L C C H I L D T r e e I n v e n t o r y J a n u a r y 5 th, 2 0 2 1 P a g e | 4 1978 Red alder (Alnus rubra) 12 25 Dead Remove Dead snag. Will impact driveway when it fails. 1977 Black cottonwood (Populus trichocarpa) 31 100 Declining Remove Upper canopy is dead. Will impact parking lot when dead trunks or branches fail. 1976 Black cottonwood (Populus trichocarpa) 32 100 Declining Remove Upper canopy is dead. Will impact parking lot when dead trunks or branches fail 2613 Big leaf Maple (Acer macrophyllum) 20 45 Dead Remove Will impact parking lot when tree fails. 2495 Big leaf Maple (Acer macrophyllum) 12 30 Declining Remove Decay at parent branch connection. Will school walkway when tree fails. 2022 Big leaf Maple (Acer macrophyllum) 50 50 Dead Kretzchmaria duesta (aggressive root and trunk decay organism) Remove 7 trunks. Will impact parling lot when tree fails. 1926 Black cottonwood (Populus trichocarpa) 75 100 Dead Three trunks Remove Two trunks at grade. Will impact parling lot when tree fails. 1994 Big leaf Maple (Acer macrophyllum) 10 35 Dead Remove Will impact parling lot when tree fails. 1687 Big leaf Maple (Acer macrophyllum) 13 50 Declining Kretzchmaria duesta, Ganoderma sp. (aggressive root and trunk decay organisms) Remove or reduce to wildlife snag, if safe to climb Previous failure. R i p p e y A r b o r i c u l t u r e L L C C H I L D T r e e I n v e n t o r y J a n u a r y 5 th, 2 0 2 1 P a g e | 5 1808 Red alder (Alnus rubra) 20 45 Dead Remove or reduce to wildlife snag, if safe to climb 2 trunks. Will impact parling lot when tree fails. 1856 Red alder (Alnus rubra) 14 40 Dead Remove or reduce to wildlife snag, if safe to climb Will impact nature trail frequented by school children when tree fails 1853 Red alder (Alnus rubra) 14 40 Dead Remove or reduce to wildlife snag, if safe to climb Will impact nature trail frequented by school children when tree fails 1814 Red alder (Alnus rubra) 10 40 Dead Remove or reduce to wildlife snag, if safe to climb Will impact nature trail frequented by school children when tree fails 1684 Big leaf Maple (Acer macrophyllum) 26 40 Dead Pruning: remove dead 10” trunk Will impact nature trail frequented by school children when tree fails 1776 Big leaf Maple (Acer macrophyllum) 55 60 Dead Sooty bark disease (can cause respiratory infection in humans) Remove or reduce to wildlife snag, if safe to climb 5 trunks. Will impact nature trail frequented by school children when tree fails 1775 Big leaf Maple (Acer macrophyllum) 10 40 Dead Remove or reduce to wildlife snag, if safe to climb Will impact nature trail frequented by school children when tree fails 1774 Big leaf Maple (Acer macrophyllum) 12 40 Dead Remove or reduce to wildlife snag, if safe to climb Will impact nature trail frequented by school children when tree fails 1755 Big leaf Maple (Acer macrophyllum) 24 40 Declining Kretzchmaria duesta (aggressive root and trunk decay organism) Remove or reduce to wildlife snag, if safe to climb Two trunks. Very decayed. Will impact nature trail R i p p e y A r b o r i c u l t u r e L L C C H I L D T r e e I n v e n t o r y J a n u a r y 5 th, 2 0 2 1 P a g e | 6 Exhibit Map The subject property. The approximate property line is indicated with red lines. The approximate locations of trees are designated with red X’s for those to be removed and green leaves for those to be pruned. Photo from King County Parcel Viewer, 2019. North is up. R i p p e y A r b o r i c u l t u r e L L C C H I L D T r e e I n v e n t o r y J a n u a r y 5 th, 2 0 2 1 P a g e | 7 Developed southern half of the property R i p p e y A r b o r i c u l t u r e L L C C H I L D T r e e I n v e n t o r y J a n u a r y 5 th, 2 0 2 1 P a g e | 8 Undeveloped northern half of the property. R i p p e y A r b o r i c u l t u r e L L C C H I L D T r e e I n v e n t o r y J a n u a r y 5 th, 2 0 2 1 P a g e | 9 Photographic Evidence Tree 1888 with the to be removed dead branch encircled in red. R i p p e y A r b o r i c u l t u r e L L C C H I L D T r e e I n v e n t o r y J a n u a r y 5 th, 2 0 2 1 P a g e | 10 Tree 1869 with the to be remove dead branch over the zipline identified by red arrows. R i p p e y A r b o r i c u l t u r e L L C C H I L D T r e e I n v e n t o r y J a n u a r y 5 th, 2 0 2 1 P a g e | 11 Tree 1889 with the to be removed eastmost trunk and its hollow cavity. R i p p e y A r b o r i c u l t u r e L L C C H I L D T r e e I n v e n t o r y J a n u a r y 5 th, 2 0 2 1 P a g e | 12 Tree 1889 with the to be removed dead trunk. R i p p e y A r b o r i c u l t u r e L L C C H I L D T r e e I n v e n t o r y J a n u a r y 5 th, 2 0 2 1 P a g e | 13 . Tree 1889: Two westernmost to be removed trunks are identified by red X’s. Dead canopy of those trunks is encircled in red. Red arrows indicate to be removed dead branches. R i p p e y A r b o r i c u l t u r e L L C C H I L D T r e e I n v e n t o r y J a n u a r y 5 th, 2 0 2 1 P a g e | 14 Tree 2495 with the decay at that connection of the two parent branches encircled in red. Decay on easternmost parent branch is identified with a red arrow. R i p p e y A r b o r i c u l t u r e L L C C H I L D T r e e I n v e n t o r y J a n u a r y 5 th, 2 0 2 1 P a g e | 15 Tree 2022 is dead and will impact the parking lot when it fails.