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HomeMy WebLinkAboutTR_Arborist_Report_180308_v1FORESTRY AND VEGETATION MANAGEMENT SPECIALISTS WFCI 3601943-1 723 FAX 3601943-4 1 28 1919 Yelm Hwy SE, Suite C Olympia, WA 98501 URBANIRURAL FORESTRY TREE APPRAISAL HAZARD TREE ANALYSIS RIGHT-OF-WAYS VEGETATION MANAGEMENT ENVIRONMENTAL STUDIES CONTRACT FORESTERS Member of International Society of Arboriculture and Society of American Foresters - Tree Protection Plan - HANSEN OUTDOOR STORAGE 800 16th St. SW Renton, Washington Prepared for: Barghausen Consulting Engineers, Inc. Prepared by: Washington Forestry Consultants, Inc. Date: March 5, 2018 Introduction The project proponent is planning to expand the parking lot of an existing office building into an outdoor storage area on 3.25 acres at 800 16TH St. SW in Renton, Washington. The proponent has retained WFCI to: • Evaluate and inventory all trees on the site pursuant to the requirements of the City of Renton Tree Protection Ordinance. • Make recommendations for retention of significant trees, along with required protection and cultural measures. Observations Methodology In accordance with Renton Municipal Code 4-4-130, WFCI has evaluated all significant trees on site. This includes cottonwood and red alder trees 8 inches diameter at breast height (DBH) and larger, and all other trees 6 inches DBH and larger, and assessed their potential to be incorporated into the new project. All trees were numbered at their base with blue paint The tree evaluation phase used methodology developed by Nelda Matheny and Dr. James Clark in their 1998 publication Trees and Development: A Technical Guide to Preservation of Trees During Land Development. Hansen Outdoor Storage – Tree Protection Plan Washington Forestry Consultants, Inc. Page 2 Site Description The site has an existing office building with an associated parking lot surrounding the building. The site is generally flat. It is bordered to the North by Interstate 405, to the south by 16th St. SW, to the east by Raymond Ave. SW, and to the west by another office building. Soils Description Soil types for this urban area are unavailable from the USDA, but the soil type in this area is likely the Snohomish silt loam. The Snohomish silt loam is a deep, poorly drained soil. It is formed in flood plains, with an alluvium parent material. The available water capacity for plants is high. The water table occurs at a depth of over 80 inches. The potential for windthrow of trees is moderate under normal conditions. Tree Conditions There are 30 significant trees on the property ranging in size from 7.5 to 67 inches in diameter at breast height (DBH). Tree condition ranges from ‘Very Poor’ to ‘Good’. Most of the planted trees are in ‘Fair’ or ‘Good’ condition. The native trees are all black cottonwood (Populus trichocarpa) that are in ‘Poor’ or ‘Very Poor’ condition. The planted tree species include Katsura (Cercidiphyllum japonicum), Japanese false-cypress (Chamaecyparis pisifera), paper birch (Betula papyrifera), and mugo pine (Pinus mugo). Photo 1: The largest tree on the site (Tree #28) is a black cottonwood in poor condition. It is a hazard tree that could potentially fail and impact targets. Decaying trunk with large dead branches, leaning over targets Targets Hansen Outdoor Storage – Tree Protection Plan Washington Forestry Consultants, Inc. Page 3 Table 1. Summary of trees at 800 16th St. SW Species DBH Range Total # of Trees # of Healthy Trees # of Trees in Poor Health Species Composition of Stand Black Cottonwood 10.5 – 67 11 0 11 36.7% Katsura 18 – 34.5 11 11 0 36.7% Paper birch 11.5 – 35 6 5 1 20% Japanese false-cypress 40 1 1 0 3.3% Mugo pine 7.5 1 0 1 3.3% 7.5 - 67 30 17 13 100% Off-Site Impacts Site development could potentially impact 3 western redcedar (Thuja plicata) trees growing on an adjacent parcel. Tree protection fencing should be placed outside the dripline of these trees to prevent damage that could result from construction activities. Photo 2: Three western redcedars growing on an adjacent parcel. Hansen Outdoor Storage – Tree Protection Plan Washington Forestry Consultants, Inc. Page 4 Discussion Potential for Tree Retention Seventeen healthy, significant trees are available for retention. From the site plan provided, at least 25 trees (including unhealthy trees) are planned for removal. Five trees along the eastern property line can be retained if protected from the impacts of construction activity. The proposed ‘save’ trees are illustrated on the site plan in Attachment 2. A detailed list of all trees (over 6 inches DBH) by species, DBH, condition, root protection zone (RPZ), save/remove potential, and retention availability is provided in Attachment 3. Tree Density Calculations Title 4-4-130 of the Renton Municipal Code requires that a minimum of 5% of all healthy significant trees in buildable areas be retained on the project in commercial or industrial developments. The following is a summary of the required and planned tree retention: Total Project Area 3.25 acres Critical Areas and Buffers 0 acres Buildable Area 3.25 acres Total Number of Significant Trees on Site based on Diameter 30 trees Trees Excluded from Retention Calculation: Trees that are Dead, Diseased, or Dangerous 13 trees Number of Healthy, Significant Trees in Buildable Area: 17 trees Required Tree Retention: 5% of healthy significant trees in buildable area: 1 trees Planned Tree Retention 5 trees Excess of Retention over the Minimum Requirement 4 trees There are 17 healthy significant trees in the buildable area of the site. At least 1 of these trees (fractions of 0.5 or higher round up to nearest whole tree) needs to be retained to meet the 5% requirement of the City of Renton Code. The proposed plan retains 5 trees, which exceeds the minimum retention requirement by 4 trees. No tree replacement will be required. The landscape plan (prepared by others) should incorporate native conifer trees along with deciduous accent and shade trees to provide a mix of color, texture, and size. Hansen Outdoor Storage – Tree Protection Plan Washington Forestry Consultants, Inc. Page 5 Recommendations Tree Protection Measures Trees to be saved must be protected during construction by a six foot high chain link fencing (Attachment #7), located at the edge of the critical root zone (CRZ). Placards shall be placed on the fencing every 50 feet indicating the words, "NO TRESPASSING - Protected Trees". The individual CRZ are a radius of one foot for each one inch of DBH (6 feet minimum), unless otherwise delineated by WFCI (see Attachment #2). Tree protection fences should be placed around the edge of the critical root zone (CRZ). The fence should be erected after logging but prior to the start of clearing. The fences should be maintained until the start of the landscape installation. There should be no equipment activity (including rototilling) within the critical root zone. No irrigation lines, trenches, or other utilities should be installed within the CRZ. Cuts or fills should impact no more than 20% of a tree’s root system. If topsoil is added to the root zone of a protected tree, the depth should not exceed 2 inches of a sandy loam or loamy fine sand topsoil and should not cover more than 20% of the root system. If roots are encountered outside the CRZ during construction, they should be cut cleanly with a saw and covered immediately with moist soil. Noxious vegetation within the critical root zone should be removed by hand. If a proposed save-tree must be impacted by grading or fills, then the tree should be re-evaluated by WFCI to determine if the tree can be saved with mitigating measures, or if the tree should be removed. Pruning and Thinning All individual trees to be saved near or within developed areas should have their crowns raised to provide a minimum of 8 feet of ground clearance over sidewalks and landscape areas, 15 feet over parking lots or streets, and at least 10 feet of building clearance. All pruning should be done according to the ANSI A300 standards for proper pruning, and be completed by an International Society of Arboriculture Certified Arborist®, or be supervised by a Certified Arborist®. Conclusions and Timeline for Activity 1. 5 trees are proposed to be retained on the site in the buildable area. 2. The final, approved tree protection plan map should be included in the construction drawings for bid and construction of the project and should be labeled as such. 3. Complete all necessary pruning on save trees to provide at least 8’ of ground clearance near sidewalks and trails, and 15’ above all driveways or access roads. 4. Install tree protection fences along the 'limits of construction'. The fences should be located at the limits of construction or 5 feet outside of the dripline of the save tree or as otherwise specified by WFCI. Hansen Outdoor Storage – Tree Protection Plan Washington Forestry Consultants, Inc. Page 6 5. Contact WFCI to attend pre-job conference and discuss tree protection issues with contractors. WFCI can verify all trees to be saved and/or removed are adequately marked for retention. 6. Complete clearing of the project. No equipment should enter the tree protection areas during logging. 7. Complete grading and construction of the project. Maintain fences throughout construction. Summary The City of Renton Municipal Code requires 1 of the 17 significant trees be retained on the buildable area of the site. This plan retains 5 trees, which exceeds the minimum tree retention requirement. Please give us a call if you have further questions. Respectfully submitted, Washington Forestry Consultants, Inc. Galen M. Wright, ACF, ASCA Riley Stark, Professional Forester ISA Bd. Certified Master Arborist PN-129B ISA Certified Arborist®, Certified Forester No. 44 Municipal Specialist, PN-7780AM ISA Tree Risk Assessor Qualified ISA Tree Risk Assessor Qualified Hansen Outdoor Storage – Tree Protection Plan Washington Forestry Consultants, Inc. Page 7 Attachment 1. Aerial Photo of Hansen Outdoor Storage Site (King County Parcel Viewer) Approximate Site Boundary N Attachment 2. Site Plan/Tree Map Approximate Site Boundary Location of Tree to be Retained Location of Tree to be Removed Location of Off-Site Trees Location of Tree Protection Fencing 30 1 2 3 4 17 24 23 22 21 20 19 18 16 15 14 13 12 29 11 10 9 8 6 5 27 25 26 28 7 Hansen Outdoor Storage – Tree Protection Plan Washington Forestry Consultants, Inc. Page 9 Attachment 3. List of Trees at 800 16th St. SW Tree # Species DBH (in.) Condition Critical Root Zone (ft. radius) Site Plan Save/Remove Notes 1 Katsura 20.5 Fair 15 Save 2 Japanese false- cypress 40 Fair 26 Save 3 Katsura 20.5 Good 16 Save 4 Katsura 19 Fair 15 Save 5 Paper Birch 11.5 Fair - Remove 6 Paper Birch 19.5 Fair - Remove 7 Paper Birch 35 Good - Remove 8 Paper Birch 21.5 Fair - Remove 9 Paper Birch 12.5 Poor - Remove In Decline 10 Paper Birch 14 Fair - Remove 11 Katsura 20 Good - Remove 12 Katsura 21 Good - Remove 13 Katsura 18 Good - Remove 14 Katsura 24 Good - Remove 15 Katsura 13, 8.5 Fair - Remove 16 Katsura 25 Good - Remove 17 Katsura 34.5 Good - Remove 18 Black Cottonwood 25 Poor - Remove In Decline 19 Black Cottonwood 25.5 Poor - Remove Suppressed 20 Black Cottonwood 10.5 Very Poor - Remove Suppressed 21 Black Cottonwood 36, 13.5 Poor - Remove In Decline 22 Black Cottonwood 13.5 Poor - Remove Suppressed 23 Black Cottonwood 14 Poor - Remove Heavy Lean 24 Black Cottonwood 25, 11 Poor - Remove Stem Decay 25 Black Cottonwood 26.5 Poor - Remove In Decline 26 Black Cottonwood 16 Poor - Remove Suppressed 27 Black Cottonwood 29 Poor - Remove Leaning, In Decline 28 Black Cottonwood 67 Poor - Remove Hazard Tree 29 Mugo Pine 7.5 Poor - Remove Leaning 30 Katsura 26.5 Fair 18 Save Hansen Outdoor Storage – Tree Protection Plan Washington Forestry Consultants, Inc. Page 10 Attachment 4. Tree Protection Fence Detail Temporary Chain-Link on Driven Posts Hansen Outdoor Storage – Tree Protection Plan Washington Forestry Consultants, Inc. Page 11 Attachment 5. Individual Tree Rating Key for Tree Condition RATING SYMBOL DEFINITION Very Good VG • Balanced crown that is characteristic of the species • Normal lateral and terminal branch growth rates for the species and soil type • Stem sound, normal bark vigor • No root problems • No insect or disease problems • Long-term, attractive tree Good G • Crown lacking symmetry but nearly balanced • Normal lateral and terminal branch growth rates for the species and soil type • Minor twig dieback O.K. • Stem sound, normal bark vigor • No root problems • No or minor insect or disease problems – insignificant • Long-term tree Fair F • Crown lacking symmetry due to branch loss • Slow lateral and terminal branch growth rates for the species and soil type • Minor and major twig dieback – starting to decline • Stem partly unsound, slow diameter growth and low bark vigor • Minor root problems • Minor insect or disease problems • Short-term tree 10-30 years Poor P • Major branch loss – unsymmetrical crown • Greatly reduced growth • Several structurally import dead or branch scaffold branches • Stem has bark loss and significant decay with poor bark vigor • Root damage • Insect or disease problems – remedy required • Short-term tree 1-10 years Very Poor VP • Lacking adequate live crown for survival and growth • Severe decline • Minor and major twig dieback • Stem unsound, bark sloughing, previous stem or large branch failures, very poor bark vigor • Severe root problems or disease • No or minor insect or disease problems • Mortality expected within the next few years Dead DEAD • Dead Hansen Outdoor Storage – Tree Protection Plan Washington Forestry Consultants, Inc. Page 12 Attachment 6. Description of Tree Evaluation Methodology The evaluation of the tree condition on this site included the visual assessment of: 1. Live-crown ratio, 2. Lateral and terminal branch growth rates, 3. Presence of dieback in minor and major scaffold branches and twigs, 4. Foliage color, 5. Stem soundness and other structural defects, 6. Visual root collar examination, 7. Presence of insect or disease problems. 8. Windfirmness: if tree removal will expose this tree to failure. In cases where signs of internal defect or disease were suspected, a core sample was taken to look for stain, decay, and diameter growth rates. Also, root collars were exposed to look for the presence of root disease. In all cases, the overall appearance of the tree was considered relative to its ability to add value to either an individual lot or the entire subdivision. Also, the scale of the tree and its proximity to both proposed and existing houses was considered. Lastly, the potential for incorporation into the project design is evaluated, as well as potential site plan modifications that may allow otherwise removed tree(s) to be both saved and protected in the development. Trees that are preserved in a development must be carefully selected to make sure that they can survive construction impacts, adapt to a new environment, and perform well in the landscape. Healthy, vigorous trees are better able to tolerate impacts such as root injury, changes in soils moisture regimes, and soil compaction than are low vigor trees. Structural characteristics are also important in assessing suitability. Trees with significant decay and other structural defects that cannot be treated are likely to fail. Such trees should not be preserved in areas where damage to people or property could occur. Trees that have developed in a forest stand are adapted to the close, dense conditions found in such stands. When surrounding trees are removed during clearing and grading, the remaining trees are exposed to extremes in wind, temperature, solar radiation, which causes sunscald, and other influences. Young, vigorous trees with well-developed crowns are best able to adapt to these changing site conditions. Hansen Outdoor Storage – Tree Protection Plan Washington Forestry Consultants, Inc. Page 13 Attachment 7. Glossary of Forestry and Arboricultural Terminology DBH: Diameter at Breast Height (measured 4.5 ft. above the ground line on the high side of the tree). Live Crown Ratio: Ratio of live foliage on the stem of the tree. Example: A 100’ tall tree with 40 feet of live crown would have a 40% live crown ratio. Conifers with less than 30% live crown ratio are generally not considered to be long-term trees in forestry. Crown: Portion of a trees stem covered by live foliage. Crown Position: Position of the crown with respect to other trees in the stand. Dominant Crown Position: Receives light from above and from the sides. Codominant Crown Position: Receives light from above and some from the sides. Intermediate Crown Position: Receives little light from above and none from the sides. Trees tend to be slender with poor live crown ratios. Suppressed Crown Position: Receives no light from above and none from the sides. Trees tend to be slender with poor live crown ratios. Hansen Outdoor Storage – Tree Protection Plan Washington Forestry Consultants, Inc. Page 14 Attachment 8. Assumptions and Limiting Conditions 1) Any legal description provided to the Washington Forestry Consultants, Inc. is assumed to be correct. Any titles and ownership's to any property are assumed to be good and marketable. No responsibility is assumed for matters legal in character. Any and all property is appraised or evaluated as though free and clear, under responsible ownership and competent management. 2) It is assumed that any property is not in violation of any applicable codes, ordinances, statutes, or other governmental regulations, unless otherwise stated. 3) Care has been taken to obtain all information from reliable sources. All data has been verified insofar as possible; however, Washington Forestry Consultants, Inc. can neither guarantee nor be responsible for the accuracy of information. 4) Washington Forestry Consultants, Inc. shall not be required to give testimony or to attend court by reason of this report unless subsequent contractual arrangements are made, including payment of an additional fee for such services as described in the fee schedule and contract of engagement. 5) Loss or alteration of any part of this report invalidated the entire report. 6) Possession of this report or a copy thereof does not imply right of publication or use for any purpose by any other than the person to whom it is addressed, without the prior expressed written or verbal consent of Washington Forestry Consultants, Inc. 7) Neither all or any part of the contents of this report, nor copy thereof, shall be conveyed by anyone, including the client, to the public through advertising, public relations, news, sales or other media, without the prior expressed written or verbal consent of Washington Forestry Consultants, Inc. -- particularly as to value conclusions, identity of Washington Forestry Consultants, Inc., or any reference to any professional society or to any initialed designation conferred upon Washington Forestry Consultants, Inc. as stated in its qualifications. 8) This report and any values expressed herein represent the opinion of Washington Forestry Consultants, Inc., and the fee is in no way contingent upon the reporting of a specified value, a stipulated result, the occurrence neither of a subsequent event, nor upon any finding in to reported. 9) Sketches, diagrams, graphs, and photographs in this report, being intended as visual aids, are not necessarily to scale and should not be construed as engineering or architectural reports or surveys. 10) Unless expressed otherwise: 1) information contained in this report covers only those items that were examined and reflects the condition of those items at the time of inspection; and 2) the inspection is limited to visual examination of accessible items without dissection, excavation, probing, or coring. There is no warranty or guarantee, expressed or implied, that problems or deficiencies of the tree or other plant or property in question may not arise in the future. Note: Even healthy trees can fail under normal or storm conditions. The only way to eliminate all risk is to remove all trees within reach of all targets. Annual monitoring by an ISA Certified Arborist or Certified Forester will reduce the potential of tree failures. It is impossible to predict with certainty that a tree will stand or fail, or the timing of the failure. It is considered an ‘Act of God’ when a tree fails, unless it is directly felled or pushed over by man’s actions.