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TR-2017-23 Arborist Report.pdf WILSON & ASSOCIATES LANDSCAPE ARCHITECTURE 815 SAN DIEGO ROAD�BERKEIEY,CA 94707 PH:510-644-9602�E:cwilson615@gmail.com Date: June ll, 2016 Re: Arborist Report Building at 21625, 21627, 21631 Stevens Creek Blvd. Cupertino, California Re: Existing Trees Memo: As requested, we evaluated two existing trees at the above referenced proper[y at the northwest comer of Stevens Creek Blvd. and Peninsula Ave. in Cupertino. We visited the site on the morning Friday July 31, 2015 to evaluate these existing trees and again on the morning of Saturday, June 11, 2016. The site currently has a two story office building and parking lot on a level site. There is existing perimeter landscape planting in fair to good condition. There were two large trees we were asked to evaluate. Tree No. 1.Eucalyptus sideroxylon /Pink Ironbark. Situated on the reaz, northeast side of building between the building and the Peninsula Avenue sidewalk. 40" DBH(Diameter at Breast Height). Approximately 50'height and 40'spread. Fair to good health condition. Fair to poor branching and structure. Probably several decades old. Likely it was planted when the building was constructed. This is not a native species, and is not particularly valuable. This tree is typical of a lree of this age and species in that it had rapid growth, has a high crown, single tnmk, and poor branching structure in the upper crown. It appears to have been correctively pruned fairly recently. It leans away from the building towards the street. The extensive aggressive root system has begun to damage the sidewalk, adjacent exterior stainvay into the building, and a utility pad under the stairway, which were all being lifted up by the tree roots. The stauway to the second floor's support posts and footings are severely damaged. The building foundations are also being affected by the tree roots. Although this tree is in relatively good condition, it has grown too large for its small planting azea, is out of scale with the building, is a species very susceptible to limb breakage, and needs substantial supplementary irrigation. Tree No. 2. Eucalyptus sideroxylon/Pink Ironbark. Situated on the front, south side of the building betv✓een the building and the Stevens Creek Blvd. sidewalk. 30" DBH. Approximately 50' height and 40' spread. Fair to good health condition. Fair to poor branching and structure. Also likely planted when the building was constructed. Similar to the Tree No. 1 noted above in age, structure, health and condition. Although planted in an even smaller planting area, there is not as much root damage to adjacent structures evident. This tree has a substantial lean out into the street. Indeed nearly all the crown of the tree overhangs the sidewalk and street. Arborist Report June 11, 2016 21625,21627, 21631 Stevens Creek Blvd.,Cupertino Page 2 of 5 Again, although this tree is in relatively good condirion, it has substanrially overgrown its planting azea, is out of scale with the building and would be even more susceptible to possible damage to the street and property due to its structural deficiency. This tree and its roots are also damaging the nearby stairway to the second floor and appeaz to be affecting the building foundations. Although both these trees area in relatively good health, we would recommend their removal and replacement with a better suited species at this time. They have out-grown their aesthetic utility, wiil cause even more damage to the surrounding structures in the future, could cause substantial property damage from limb drops, and would require frequent pruning and thinning. Recommended replacement trees might be: {�� r � �/' • Geijera parvt Austr ' Willow �IJtLU� ��� N' �� o��"t �t � • Lagerstroemia h � s e Myrtle Eoth of these trees are smaller stature, ore manageable trees. Eoth were seen in the �- neighborhood and were performing well. These trees might be planted from 15 gallon can or 24" box specimen nursery stock. Please contact us with any quesrions. Sincerely, (JV�`6 l�u�tSGo � Charles Wilson ISA Arborist WE-7138A Justification Statement Requested Action:tree removals at 21625 Stevens Creek BIvd,95014 APN#:Traa 8822; Lot 33 Property Owner: Eugene Mandere Projed Contact:Sharon Hill 408-833-5668 sharonhilidesign@ protonmail.com We request to remove two Eucolyptus nicholii on said property located at the intersection of Stevens Creek Blvd and Peninsula Avenue.These mature eucalyptus provide significant urban canopy; and, despite issues they have presented over time with lifting of concrete pads and auxiliary building structures,we have faithfully pruned and maintained them according to ISA standards with the belief that the issues they pose are outweighed by the aesthetic beauty they offer. However, recently we discovered a significant amount of root and trunk rot on the tree along Peninsula Avenue, Specimen C, to such a degree that there is great concern for the immediate safety of the general public due to both the size of the tree and its proximity to pedestrian rights of way and traffic on Peninsula Avenue. An examination of the trunk and buttress roots revealed bark which easily falls away. The trunk wood is damp and crumbly. An examination of some of the larger Iateral roots revealed the same. Due to the lean of the tree,these roots would be its main stabilizing force and they are clearly compromised to the extent that at least twenty-five to thirty percent of the trunk all the way around the tree and lateral roots, located on the building side of the tree,are thoroughly rotted and a visual inspection makes clear just how significant it is. The soil is soft and spongy from the decay of the absorbing roots where it was once firm and impossible to excavate. Please see accompanying photos as Eucalyptus(A). Furthermore,on March 30, a Iimb of 8' diameter and approximately 10' long came down and the decay is very visible in the limb( see accompanying photos) indicating it has spread throughout the tree.The limb also damaged a AT&T utility line which had to be repaired and this particular location is a main infrastructure point. The Eucalyptus tree situated along Stevens Creek does not display the same degree of decay and rot as Specimen C; however,a significant chunk of rot has been detected on the building side of this tree and that rot extends to some of the lateral roots that anchor this tree which leans even more than Specimien C. It is not known at this time what the extent of the decay is, but some termite pilings were visible on the bark and both trees seem to have been equally affected by recent sidewalk replacement work.This tree has more structural defects in that most of the crown is supported by two co-dominant leaders from which other main branches arise from narrow angles of attachment. Independently,this is not of the greatest concern as mitigation measures can and have been performed to reduce load on weak attachments; however,the visual observation of decay combined with the inherent structural weakness presents a different scenario. In addition, accompanying photos display splitting and fissuring of the bark which is more than what we are accustomed to seeing on this tree. Moreover,the tree, located not more than 12"from the building, and its ability to develop and maintain sufficient anchoring roots to offset the degree of lean and preponderance of canopy in the upper third of the tree in this limited space is clearly in question particularly with decay present. What is known is that both trees were in relatively good health not long ago.They had been pruned in 2014 and were inspected and deemed healthy, albeit limited by their relative incompatibility with their location.The soil around them was very firm and planting anywhere near them was impossible. Now, we find, around both trees,the soil to be spongy, loose, and composed largely of decaying woody material. In both cases,we noted that the sidewalk work seems to correlate with a significant change in the health of these trees. In three years, never has a single limb broken from either of these trees until now and the process of decay seems to be occurring rether rapidly. While Specimen A may not visually display decay to the extent of that of Specimen C, it is logical to infer the eventual outcome will be similar given the trees are of the same age and variety, and similar proximity to recent construction. In regard to Specimen A,we feel it is imperative to remove the tree immediately.There can be no doubt as to the extent of decay and it is clearly a liability issue. With Specimen A, it is most likely a matter of time before the extent of decay is as apparent.This tree, however, is actually more dangerous in terms of its structure, lean,and amount of canopy at least thirty feet above ground and over sidewalks and Steve�s Creek Boulevard. In addition, its focation in such close proximity to existing structures is not acceptable by more recent standards which stipulate the hazards to foundations by placing trees so close to them. We understand removal of trees in a planned development is a process and support wholeheartedly the importance of urban canopy. However, we request that a permit for the removal of Specimen A be issued immediately due to the increasing level of urgency associated with its rapid deterioretion and that an examination of Specimen A be performed whereby we believe a similar conclusion will be reached. We would like a permit to remove both trees and replace them as soon as possible. �y`� • " c 4 x . . T ' �`��'� � � ��� v � " ` � �,3 .�, . '" � . � 4; �� t ;� � 1 , � . ��L,. - � . ., � � ' . 4 y �� �s _Y., . -�` �. . . y ��. ,-3�.. � s, . ;o, � , . . ..., -. � � � ' � -:A,1 . . . d ._� . :� f.,.. �' `S�".� � , ._1� .. ..�} � t f�',���� _ 24� �.�� � \, -; � � t <.z� _. - � �� . r �-.��`i' �. .'a�{� . i.3 � R ..: � ��i:� w`y,._ - ' , fh ' r -�+�',�. . .\�� �: ..� - - . S� t � . 4� � r -� �a� �. �i� �. . 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