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Hazard tree removal STF2021-0009CITY OF EDMONDS 121 5tn Avenue North, Edmonds WA 98020 Phone: 425.771.0220 • Fax: 425.771.0221 • Web: www.ci.edmonds.wa.us DEVELOPMENT SERVICES DEPARTMENT • PLANNING DIVISION "ne. I STJ April 13, 2021 John and Veronica Gates 750 Northstream Ln. Edmonds, WA 98020 Subject: Hazard Tree Removal (STF2021-0009) Mr. & Mrs. Gates, The City of Edmonds has received documentation regarding a request for hazard tree removal. Jorgen Olson a certified arborist has recommended removal of four (4) Birch trees located at 750 Northstream Ln. The subject property contains slopes greater than 25% according to the City's LiDAR information as well as a stream, which are considered critical areas pursuant to Edmonds Community Development Code (ECDC) Chapters 23.40, 23.80 and 23.90. Generally, the removal of trees or vegetation within a critical area or a critical area buffer is not an allowed activity unless it involves the removal of invasive species or hazard trees pursuant to ECDC 23.40.220.C.8. Normal maintenance of vegetation is an allowed activity in critical areas. "Normal maintenance of vegetation" is defined as "removal of shrubs/nonwoody vegetation and trees (less than four -inch diameter at breast height) that occurs at least every other year. Maintenance also may include tree topping that has been previously approved by the city in the past five years." In this case, the subject Birch trees are larger than 4" DBH so tree hazard evaluation is required. A Geotech report and an Arborist, prepared by Jorgen Olson (PN-6978A) was submitted regarding removal of four (4) Birch trees. The subject trees were located in a low topographical area of the property, with a creek running nearby and have been vista pruned for many years. According to the reports, photos and descriptions provided, the subject Birch trees have shown decay from previous large cuts throughout the crown, with noticeable decay columns moving down the trunk form the original topping cuts. The arborist has noted that one of the removed birch trees had previously failed. Additionally, it has been noted in the reports that the trees showed signs of dieback indicative of the bronze birch borer. Due to the high risk for failure of the trees they were candidates for removal. Pursuant to ECDC 23.40.220.C.8.b.iv each hazard tree removed must be replaced with new trees at a ratio of two to one. Patrick See a certified arborist (PN-1463A) has confirmed that twelve (12) vine -maples have been planted two (2) to three (3) feet from the location from where the trees had been removed. An exemption for tree cutting has been granted with the following conditions: 1. Only the identified Birch trees may be cut as identified in the reports. In order to avoid potential code violations and associated fees, any future tree removal, tree topping, and any new cutting of existing trees may require additional documentation or permits. Please check with the city prior to any new cutting or tree removal that has not been part of the existing on -going maintenance at the subject site. If you have any questions, please let me know via email at michele.szafran@edmondswa.gov or you may call 425-771-0220 to speak with the Planner on duty. Sincerely, Michele Q. Szafran Planner Encl: Arborist Report Arborist Replanting Letter Geotech Report Photos Site Plan Ouu/iu liruui 1111%- 25920132" d St. SE Monroe, WA 98272 360-217-7535 John Gates 750 Northstream Lane Edmonds, WA 98020 SUBJECT: Tree risk assessment of birch trees located on the property Assignment On February 3, 1 was called by a neighbor of John Gates, who informed me that John had received a letter from the city of Edmonds. This letter required a certified arborist to evaluate birch trees which had been previously removed. As a certified arborist and tree risk assessor, and one that has worked on the trees a few times in the past, I was the perfect choice for the task. Methods To evaluate the trees and to prepare this report, I drew upon my education and experience of 15 years in the fields of horticulture and arboriculture. Also, I followed the protocol of the International Society of Arboriculture for Hazard Tree Assessment while looking at the overall health of the tree and the site conditions. This is a scientifically based process to look at the entire site, the surrounding land and the soil, as well as a complete look at the trees. Although an examination was not my primary objective when I was working on the trees, I do examine trees that I am going to climb. In examining these trees, I looked at such factors as size, vigor, crown ratio and class, density of foliage, injury, insect activity, root damage and root collar health, crown health, dead wood and hanging limbs. I also looked closely for structural defects and tree components that may be too large and prone to break. Observations and Recommendations The trees are in a low topographical area of the property, with a creek running nearby, and situated in a view corridor for many residents to the east. As such, the trees had been vista pruned for many years. The resulting form of the trees from continual vista pruning left unusually large lateral branches near the crown of the tree and enlarged lateral branches slightly below the crown. Decay from previous large cuts were evident throughout the crown, with noticeable decay columns moving down the trunk from the original topping cuts. These decay columns weakened the attachment point of the large lateral limbs near the crown. To a climber in the tree, that mea^t be carcful not to venture out on those lateral limbs_ The possibility of failure was greater than usual. One of the removed birch trees had previously failed. This was obvious in the 90 degree bow in U le a ui Ak c iai + iI + f 1 U— i later al —1 uwul 'to VCiiiGaI -1-uwih. Each year I pruned the trees, I noted apical dieback that is indicative of bronze birch borer. These insects cause a dcgoncrntive condition that cvontually leads to complete tree death_ Each of the trees were in different stages of the attack, but all showed symptoms. Given the John Gates Page. 1 2/4/2021 13OU/1U !ir U L.Li I1 25920 132 ndSt. SE Monroe, WA 98272 360-217-7535 proximity to the creek, insecticide treatment was not a good option. I recommended removal at some time in the future and replacement with a species that would not be susceptible to this aggressive insect. Replacement with a native species that is both resistant or not susceptible to the bronze birch borer, and also fits in the confines of the vertical space afforded, is the best choice for the area. This will ensure a sustainable tree that requires very little vista pruning. Recommended trees for replacement include vine maple Acer circinatum, river birch Betula nigra (high resistance to the bronze birch borer), weeping willow (Salix babylonica), black hawthorn Crataegus douglasii, and pacific crab apple Malus fusca. I hope this report gives you some useful knowledge about the trees located on your property. Sincerely, Jorgen Olson ISA Certified Arborist # PN-6978A ISA Tree Risk Assessor John Gates Page 2 2/4/2021. ,i s v 2R- t ;dl 5t'ieR w. �— ,14qI-�,it Pat's Trees and Landscape Inc. P.O Box 82514 Kenmore, WA 98028 1-425-766-4482 General Contractor # PATSTTL859KM pseestrees@hotmail.com Mr. Gates 750 Northstream Ln. Edmonds, WA 98020 REFF: TREE PLANTING PRACTICES Dear Mr. Gates In accordance with your request on April 6, 2021. 1 performed an inspection of your property at 750 Northstream Ln Edmonds, WA 98020 Scope of Work The purpose for doing the health inspection is to establish where to plant the trees on your hill side by the stream. Investigative Work We began the investigative work by walking the property. To determine the condition of soil and sun light for the trees new location. When during the investigation, we identified were to put them as well as where the high-water mark is. Conclusions and Recommendations The twelve vine -maple are being planted two to three feet from the location from where the trees were taken down. These trees were plant with an organic fertilizer called M-roots. The trees will be inspected by myself in June of 2021 as well as September to insure they are alive and doing well. Sincerely Yours, Patrick See ISA Certified Arborist #PN-1463A Pats Trees and Landscaping, Inc. WAIVER OF LIABILITY: Pat's Trees and Landscape Inc. P.O Box 82514 Kenmore, WA 98028 1-425-766-4482 General Contractor # PATSTTL859KM pseestrees@hotmail.com There are many conditions affecting a tree's health and stability which may be present and cannot be ascertained, such as, root rot, previous or unexposed construction damage, internal cracks, stem rot and more which may be hidden. Changes in circumstances and conditions can also cause a rapid deterioration of a tree's health and stability. While I have used every reasonable means to examine these trees, this evaluation represents my opinion of the tree health at this point in time. These findings do not guarantee future safety nor are they predictions of future events. Thank you for considering us for your arboricultural needs. I hope this report answers your questions. Please call me if I can provide more information or be of further service. REFERENCES CONSULTED: 1. A new tree biology: by Alex L. Shigo 2. The new tree biology dictionary: by Alex L. Shigo 3. The Tree Doctor: by Daniel Prendergast, Erin Predergast 4. Western Gardening Book 5. Trees and Shrubs of Washington by: C.P. Lyons 2 GEOTECH CONSULTANTS, INC_ John Gates 750 Northstream Lane Edmonds, Washington 98020 via email. alibrow me.com; gerarden2(a_me.com Subject: Geotechnical Engineering Considerations Tree Cutting at a Residential Property 750 Northstream Lane Edmonds, Washington Greetings: 2401 1 Oth Ave E Seattle, Washington 98102 (425) 747-5618 March 4, 2021 JN 21099 The undersigned Principal of Geotech Consultants met with you at your residential property on February 21. We were informed prior to our arrival that four trees had been cut down on the property about a month prior, and that the City of Edmonds was requesting some geotechnical engineering information with regards to the cutting down of the trees. This letter provides our conclusions and recommendations regarding the tree removals from a geotechnical engineering standpoint. The Gates property is fairly level on its northeastern portion, and a residence is located there. A fairly flat yard area is located to the south of the residence. However, there is a creek that exists on mostly the southern portion of the property, that also wraps around the southwestern portion, that is lower than the northeastern portion of the property. There is a somewhat level "swale" that is about 10 to 20 feet wide which the creek flows through; this Swale is about 10 feet lower than the northeastern portion of the property. There is a steep slope that is about 8 to 10 feet tall between the northeastern portion of the property and the northern/northeastern side of the Swale. Another steep slope rises about 10 to 12 feet upward from the swale/creek on the southern/southwestern side of the Swale; a street and driveway are located at the top of this slope. Based on information from the City of Edmonds GIS website, the steep slopes on the sides of the Swale are considered Landslide Hazard Area because of their height and steepness. Within the Gates property, the general vegetation covering the steep slopes consists mostly of grass on the northern/northeastern side of the Swale and blackberries on the southern/southwestern side. The base of the Swale is mostly grass covered. There are some scattered, medium-sized trees in the Swale and steep slopes, and it is very apparent where the four, recently -cut -down trees existed in this area --- this is because stumps that extend about 6 inches or so above the surrounding ground. We observed that two of the cut -down trees, which ranged in diameter of about 10 to 12 inches, were located within the relatively flat Swale, while the two others that were in the range of 14 inches were located on the steep slope above the southern side of the Swale. We did not observe any signs of instability or ground disturbance around the areas where the trees were cut down. We received a copy of a report from a certified arborist who removed the birch trees. They stated that the trees needed to be cut down so that they could be replaced with a more suitable species. This arborist is the one who cut down the four trees. The arborist has made recommendation for the more appropriate species that should be planted to replace the birch trees. GEOTECH CONSULTANTS, INC. Gates March 4, 2021 CONCLUSIONS AND RECOMMENDATIONS JN 21099 Page 2 In are professional opinion, from a geotechnical engineering standpoint, the cutting down of the four trees is suitable provided new trees be planted (as recommended by the arborist) in the very near future. The main reason for this opinion is that the roots of the trees were left in -place, and these roots will remain for quite some time; it is the roots that provide stability to the ground under/around a tree. Eventually the roots will rot out, but the new trees will grow in the meantime whose new roots will take over for the rotted ones. We also have this opinion because there was no ground disturbance done in the area of the cut -down trees. Because the trees, especially to two located on the swale's southern slope, are located in a Landslide Hazard Area or their buffers per Edmonds Code, their removal is considered an "alteration" to the code (Section 23.80.060/70). There are several statements noted in this section of the code that need to be address because of this alteration. We have included most of these comments from the code below (bolded), and they are followed by our responses (in italics). Alterations of geologically hazardous areas or associated buffers may only occur for activities that: 1. Will not increase the threat of the geological hazard to adjacent properties beyond predevelopment conditions. We believe that, once new trees are planted, the cutting down of the four trees will not increase the threat to adjacent properties beyond the conditions prior to the cutting. 2. Will not adversely impact other critical areas. The other nearby critical area is the creek; it was not affected, nor will it be affected, because the stability to the slope and area was not changed by the cutting down of the trees; this is mainly because the stump was left intact, but also because new trees will be planted. 3. Are designed so that the hazard to the project is eliminated or mitigated to a level equal to or less than predevelopment conditions. Once the new trees are planted, the hazard level will be equal to the time prior to the cutting down of the trees. 4. Are certified as safe as designed and under anticipated conditions by a qualified engineer or geologist, licensed in the state of Washington. This is safe in our opinion. Alterations of an erosion or landslide hazard area, minimum building setback and/or buffer may only occur for activities for which a hazards analysis is submitted and certifies that: a. The alteration will not increase surface water discharge or sedimentation to adjacent properties beyond predevelopment conditions. The ground where the trees were cut down was not disturbed and ground vegetation remains. Once the new trees are planted, there will not be an increase in surface water discharge or sedimentation to the creek. b. The alteration will not decrease slope stability on adjacent properties. Because the stumps were left intact, and because new trees will be planted, the cutting of the trees did not decrease slope stability of the site's steep slopes. c. Such alterations will not adversely impact other critical areas. The other nearby critical area is the creek; it was not affected, nor will it be affected, because the stability to the slope and area was not changed by the cutting down of the trees; this is mainly because the stump was left intact, but also because new trees will be planted. GEOTECH CONSULTANTS, INC. Gates March 4, 2021 LIMITATIONS JN 21099 Page 3 The conclusions and recommendations contained in this report are based on site conditions as they existed at the time of our site visit. This report has been prepared for the exclusive use of John Gates and his representatives for specific application to this project and site. Our conclusions and recommendations are professional opinions derived in accordance with our understanding of current local standards of practice, and within the scope of our services. No warranty is expressed or implied. We appreciate the opportunity to be of service on this project. Please contact us if you have any questions, or if we can be of further assistance. 91 VATre Respectfully submitted, GEOTECH CONSULTANTS, INC. Robert Ward, P.E. Principal GEOTECH CONSULTANTS, INC. ��^ P�'�` 'y{� T 'r jjh� •. ? 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