Assessment of Six (6) Large Tree Specimens at 600 Addison Street Berkeley, California

Transcription

1 Assessment of Six (6) Large Tree Specimens at 600 Addison Street Berkeley, California Land Use Planning Received November 30, 2016 Prepared for: Jason Jones, Property Owner P.O. Box 183 Corte Madera, CA Field Visit: Walter Levison, Consulting Arborist (WLCA) 11/9/2016 Report by WLCA Version: 11/9/ of 15

2 Table of Contents 1.0 Summary Assignment & Background Observations & Discussion Tree Location Map Recommendations Author s Qualifications Assumptions and Limiting Conditions Certification Digital Images Tree Data 14 2 of 15

3 1.0 Summary Walter Levison, Consulting Arborist (WLCA) tagged and surveyed six (6) site trees per direction by the property owner. The following is a brief summary of WLCA s findings and suggestions: a. Tree #1 is a large mature coast redwood specimen near an existing asphalt parking lot. This species is a known heavy water user, a very fast grower, and one that is commonly available in the Bay Area nursery trade. This specimen is in good overall condition. b. Tree #2 is a large mature coast redwood specimen near an existing asphalt parking lot. This species is a known heavy water user, a very fast grower, and one that is commonly available in the Bay Area nursery trade. This specimen is in good overall condition. c. Tree #3 is a large mature coast redwood specimen near an existing asphalt parking lot. This species is a known heavy water user, a very fast grower, and one that is commonly available in the Bay Area nursery trade. This specimen is in good overall condition. d. Tree #4 is a large mature coast redwood specimen near an existing asphalt parking lot. This species is a known heavy water user, a very fast grower, and one that is commonly available in the Bay Area nursery trade. This specimen is in good overall condition. e. Tree #5 is a large mature coast redwood specimen near an existing asphalt parking lot. This species is a known heavy water user, a very fast grower, and one that is commonly available in the Bay Area nursery trade. This specimen is in excellent overall condition. f. Tree #6 is a coast live oak in fair overall condition in the American Soil Products yard. Coast live oaks are protected per City of Berkeley tree ordinance, which requires that a removal permit be granted by the City prior to removal of this tree. The tree has been hit by machinery or vehicles over the years, damaging as many as 8 to 10 branches and other tree portions, with breaks and scars evident that measure between 4 inches and 6 inches diameter each. The lower trunk bifurcates into two codominant mainstems with a bark inclusion at the fork. This fork is considered a structural defect which downgrades the tree s overall condition from good to fair, and the tree would require cabling or a through-bolt cable installation if it were to be retained. 2.0 Assignment & Background Walter Levison, Consulting Arborist (WLCA) was retained by Mr. Jason Jones, owner of the property known as 600 Addison, Berkeley, California, to tag with numeric tags, assess, and prepare a written arborist report on six (6) existing large mature trees on the site. The trees to be surveyed included five (5) coast redwoods (Sequoia sempervirens) at the west corner of the property near an existing asphaltic parking lot, and one (1) coast live oak (Quercus agrifolia) at the east corner of the property at the gated entrance to the American Soil Products yard. The only tree on site that appears to be regulated by the City of Berkeley tree ordinance is the coast live oak specimen. WLCA reviewed existing drawings such as a topographic survey of the site, and an initial architectural site plan rendering. A tree location map markup was prepared by WLCA using one of these sheets (see below). 3 of 15

4 Tree data was assembled using field data obtained during the author s site visit 11/9/2016 (see tree data charts below). Tree heights were verified using a digital Nikon Forestry 550 Pro hypsometer. Canopy spread was estimated visually. Trunk diameters were determined using a forester s D-tape which converts circumference inches to average diameter in inches and tenths of inches. WLCA discusses existing tree conditions and species water use and landscape use considerations in section 3.0 below. Recommendations are also included below in section 5.0, and can be utilized in the case that one or more of the survey trees is retained and protected during proposed new construction. 3.0 Observations & Discussion Trees #1, 2, 3, 4, and #5 are coast redwood (Sequoia sempervirens): a species that is typically far too large in terms of height at maturity for most residential sites in the Bay Area. However, on some commercial sites, the tree may be appropriately located if far offset from high occupancy buildings and high occupancy parking lots to avoid risk of damage and injury to life and property from tree part failure (e.g. scaffold branches falling from height, etc.). The trees are favored by many Bay Area municipalities as an iconic native California evergreen tree for high profile locations where shade and aesthetics are valuable. The reasons for this are not entirely clear, since the tree is not actually native to most of the locations where it is installed, and there are issues present at most sites where it is planted that negatively affect the tree s performance in the landscape, such as poor soil drainage, root extension impediments, lack of heavy irrigation, lack of proper atmospheric humidity that the trees require for normal growth performance (e.g. fog, etc. that is taken in by the needles as a form of needed water), height restrictions such as high voltage power lines that limit normal mainstem growth, and vertical and horizontal shading which reduces sunlight penetration to the trees. This tree is relatively very fast growing, and is therefore easily replaced and easily sourced in the retail and wholesale nursery trade throughout the San Francisco Bay Area. Given voluntary and mandatory water restrictions in the Bay Area now and into the foreseeable future, high water-use species such as coast redwood are considered by WLCA to be somewhat non-desirable in the landscape. Also note that requirements to irrigate landscape trees using municipal recycled water sources introduce ionic content (i.e. salts ) that may be damaging to coast redwoods (WLCA professional experience in the Bay Area for 18 years). If recycled water is utilized for irrigation of coast redwoods, then the recycled water must be blended with standard sourced water to reduce ionic content down below thresholds at which coast redwoods are known to be affected per the published literature reporting on this subject. Note again that this species is not native to this Berkeley flats site. Also note that most of the coast redwood specimens at this site exhibit multiple mainstems arising vertically in the uppermost sections of the canopies. This may have occurred due to splitout of the original single mainstem on each tree during storms. If the trees are retained, then these codominant mainstems would need to be pruned out to leave a single vertical mainstem on each tree. 4 of 15

5 Tree #6 is a coast live oak specimen native to this site. The tree is in only fair overall condition, and as such is not necessarily recommended to be retained. However, per City of Berkeley tree ordinance, a removal permit would be required to be approved by the City if this tree were to be removed. Although coast live oak is a native tree, the species has been decimated in recent years by issues such as sudden oak death ( SOD ) for which there is no cure. This tree is therefore no longer considered an optimal species for the Bay Area, as it is susceptible to decline and death from the SOD pathogen. Although this oak species is protected in the City of Berkeley, there are other oak species available in the nursery trade that are superior in terms of their resistance to the SOD pathogen. Impacts to Trees from Grading/Drainage/Utilities The proposed work for this site is only in conceptual stage, and therefore the survey trees are not plotted accurately on any site plan sheets that would indicate exact limits of proposed new grading, excavation, demolition, utility trenching, drain pipe trenching, etc. At the time of writing, it appears that one or more of the trees will be retained per plan. However, given that the plot locations of the trees are not currently accurate, WLCA cannot confirm disposition of the trees (e.g. remove, retain). As a general rule, arborists will often specify that if grading, excavation, or trenching is occurring on one side of a grove of trees the size of redwoods #1, 2, 3, 4, and #5, between zero and 24 inches below grade (i.e. the entire lateral woody root system of the trees), then the offset distance between mainstem edges and work limits would need to be approximately 3x to 10x the mainstem diameters as a radial distance from the mainstem edges. This equates to approximately 6 to 18 feet radial distance from mainstem edge to work limit as measured at grade (assuming work would occur only on one side of the tree grove). WLCA has simplified this offset distance recommendation to 10 to 20 feet. Coast live oak specimen #6 would probably be retainable if site work were kept at least 10 to 15 feet radial distance in all directions from the mainstem edge as measured at grade (work could occur in all areas around the tree, as long as a 20 to 30 foot diameter root protection zone were to be established as a fenced off no dig area. Note that this is the only site tree currently protected by City Ordinance. No other survey trees are protected by any City Tree Ordinance wordage. 5 of 15

6 4.0 Tree Location Map As noted on the above sheet, the upper left hand corner of the tree map markup is North. The tree mainstem plot locations are rough approximate only, and are not accurate. The above illustration is for initial reference purposes only. The trees were tagged at eye level with professional grade aluminum tags numbering from 1 through 6 for easy reference in the field. 6 of 15

7 5.0 Recommendations 1. Project Arborist ( PA ): It is suggested that a third party ASCA registered consulting arborist or ISA Certified Arborist with good experience with tree protection during construction be retained by the applicant, to provide pre-project verification that tree protection and maintenance measures outlined in this section of the arborist report are adhered to. Periodic (e.g. monthly) inspections and summary reporting, if required as a project condition of approval, are suggested in order to verify contractor compliance with tree protection throughout the site plan project. This person will be referred to as the project arborist ( PA ). The PA should monitor construction activities within 15 linear feet of any tree being retained. 2. Chain link root protection zone: Install chain link fencing panels and/or chain link material mounted on 7 foot long 2 inch diameter iron tube posts pounded 24 inches into the ground, along routes to be determined, as a root protection barrier for trees being retained (if any). Minimum linear distances for fencing as measured between tree mainstem edges and fence, at grade: (If Retained) Trees #1, 2, 3, 4, 5: 10 to 20 feet (assume work on one side of root zone only) (If Retained) Tree #6: 15 feet (assume work will potentially occur around all sides of tree root zone) See image at right. 3. Trunk buffer wraps: As protection for the above-ground portions of the trees (lower trunks), wrap 20 wraps of orange plastic snow fencing around the lower trunk of each survey tree being retained. Stand wood boards around the plastic, and secure using duct tape (see image at right). 4. Pruning: Keep all vertical airspace pruning and/or horizontal airspace clearance pruning to a minimum. 7 of 15

8 If required, then retain a local ISA Certified Arborist to perform this work in a manner that conforms to all current iterations of ANSI A300 standards for tree care. 5. Root Pruning: If any roots are encountered measuring greater than 1 inch in diameter each, then cut those roots cleanly using sharp, professional grade pruning tools, or a Sawzall with a wood pruning blade. Prune exposed roots at right angles to the root growth directions. Rebury immediately. If roots cannot be buried within 24 hours or exposure to the atmosphere, then smear wet mud over the newly cut ends, and cover with wet burlap cloth that can be wetted each day until the area is backfilled with parent soil. 6. Grading/Utility/Drainage/Excavation/Irrigation Pipe Offsets: For trees that are being retained, keep all grading, utility, drainage, irrigation pipe, and excavation work approximately 10 to 20 linear feet offset from the mainstem edges of those trees, as measured at grade elevation. Work limits should be kept to at least 2 to 4 feet outside the locations of the chain link root protection zone fence perimeters in order to avoid machinery tagging the fences with machinery bucket teeth. Consider use of pit to pit directional bore techniques to avoid pipe trenching through root zone areas of trees to be retained. 7. Irrigation: Maintain once weekly heavy irrigation year round, before, during, and after construction, applying approximately 50 to 100 gallons per tree per week to redwood trees being retained (if any). Note that irrigation water application can be performed using various methods such as garden hoses, tow-behind tanks (see image at right), water trucks, and/or other methods. 8. Wash the trees: Spray off dust every two months from the trees using a high powered hose, to clean the upper needle surfaces for optimal photosynthesis, and clean the the lower surfaces of the needles where stomata are located (the gas exchange portals where oxygen and carbon dioxide are moved). See sample image at right showing washing of 50 redwood trees using a fire department hose. 8 of 15

9 9. Landscape and Irrigation: Project team shall verify the types, trench depths, etc. of all irrigation main lines, valves, laterals, pop-ups, etc. (if any proposed) within 20 feet of any survey trees being retained. Realign any trench routes (if any) to 20 feet or more from the trees, or simply replace any proposed trenched-type piping with a no-dig type specification pipe such as black poly tubing which can be laid directly over grade or buried minimally beneath 2 to 3 inches of soil, within this distance of 20 feet from mainstem edges. 6.0 Author s Qualifications Continued education through The American Society of Consulting Arborists, The International Society of Arboriculture (Western Chapter), and various governmental and non-governmental entities. Contract Town Arborist, Town of Los Gatos, California Community Development Department / Planning Division 2015-present Tree Risk Assessment Qualified (ISA TRAQ Course Graduate, Palo Alto, California) Millbrae Community Preservation Commission (Tree Board) ASCA Registered Consulting Arborist #401 ASCA Arboriculture Consulting Academy graduate, class of 2000 Associate Consulting Arborist Barrie D. Coate and Associates 4/99-8/99 Contract City Arborist, City of Belmont, California Planning and Community Development Department 5/99-present ISA Certified Arborist #WC-3172 Peace Corps Soil and Water Conservation Extension Agent Chiangmai Province, Thailand B.A. Environmental Studies/Soil and Water Resources UC Santa Cruz, Santa Cruz, California of 15

10 (My full curriculum vitae is available upon request) 7.0 Assumptions and Limiting Conditions Any legal description provided to the consultant/appraiser is assumed to be correct. Any titles and ownership 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 and evaluated as through free and clean, under responsible ownership and competent management. It is assumed that any property is not in violation of any applicable codes, ordinance, statutes, or other government regulations. Care has been taken to obtain all information from reliable sources. All data has been verified insofar as possible; however, the consultant/appraiser can neither guarantee nor be responsible for the accuracy of information provided by others. The consultant/appraiser 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. Unless required by law otherwise, the possession of this report or a copy thereof does not imply right of publication or use for any other purpose by any other than the person to whom it is addressed, without the prior expressed written or verbal consent of the consultant/appraiser. Unless required by law otherwise, neither all nor 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 conclusions, identity of the consultant/appraiser, or any reference to any professional society or institute or to any initiated designation conferred upon the consultant/appraiser as stated in his qualifications. This report and any values expressed herein represent the opinion of the consultant/appraiser, and the consultant s/appraiser s fee is in no way contingent upon the reporting of a specified value, a stipulated result, the occurrence of a subsequent event, nor upon any finding to be reported. Sketches, drawings, and photographs in this report, being intended for visual aids, are not necessarily to scale and should not be construed as engineering or architectural reports or surveys unless expressed otherwise. The reproduction of any information generated by engineers, architects, or other consultants on any sketches, drawings, or photographs is for the express purpose of coordination and ease of reference only. Inclusion of said information on any drawings or other documents does not constitute a representation by Walter Levison to the sufficiency or accuracy of said information. Unless expressed otherwise: a. information contained in this report covers only those items that were examined and reflects the conditions of those items at the time of inspection; and b. 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 plants or property in question may not arise in the future. Loss or alteration of any part of this report invalidates the entire report. Arborist Disclosure Statement: Arborists are tree specialists who use their education, knowledge, training, and experience to examine trees, recommend measures to enhance the beauty and health of trees, and attempt to reduce the risk of living near trees. Clients may choose to accept or disregard the recommendations of the arborist, or to seek additional advice. Arborists cannot detect every condition that could possibly lead to the structural failure of a tree. Tree are living organisms that fail in ways we do not fully understand. Conditions are often hidden within trees and below ground. Arborist cannot guarantee that a tree will be healthy or safe under all circumstances, or for a specified period of time. Likewise, remedial treatments, like any medicine, cannot be guaranteed. Treatment, pruning, and removal of trees may involve considerations beyond the scope of the arborist s services such as property boundaries, property ownership, site lines, disputes between neighbors, and other issues. Arborists cannot take such considerations into account unless complete and accurate information is disclosed to the arborist. An arborist should then be expected to reasonably rely upon the completeness and accuracy of the information provided. 10 of 15

11 Trees can be managed, but they cannot be controlled. To live near trees is to accept some degree of risk. The only way to eliminate all risk associated with trees is to eliminate the trees. 8.0 Certification I hereby certify that all the statements of fact in this report are true, complete, and correct to the best of my knowledge and belief, and are made in good faith. Signature of Consultant 9.0 Digital Images WLCA archived images of the subject tree on 11/9/2016. Tree 1 Tree 2 11 of 15

12 Tree 3 Left to Right: Trees 4 & 5 Close-up of the uppermost canopy of tree 3, showing a codominant mainstem situation which is actually present on most of the redwood specimens at this site. If these trees were to be retained, it would be prudent to remove all but one single vertical mainstem per tree, to reduce the likelihood of a splitout at the codominant mainstem attachment points. Profile of tree 6, showing the evergreen canopy as viewed from just outside the American Soil Products yard entrance gate. 12 of 15

13 Close-up of the bark inclusion type fork at the lower mainstem area of tree 6. This is a significant defect that will require arborist cable installation and/or a through-bolt cable. Close-up of machinery-caused branch breakage in the canopy of tree 6. Close-up of another branch break assumedly caused by machinery impact in the lower canopy of tree of 15

14 10.0 Tree Data Tree Tag Number Genus & Species Common Name Trunk1 Diameter Trunk2 Diameter Trunk3 Diameter Sum of All Trunk Diameters Height & Canopy Spread (Ft.) Health & Structural Rating (100% Each) Overall Condition Rating (0 to 100%) Protected per City of Berkeley Oak Ordinance? (R)emove Tree (S)ave Tree (D)isposition Unclear Severity of Impacts Expected from Site Plan Related Work Multiple codominant mainstems Pests and Disease Presence, and Other Notes SUGGESTED ROOT PROTECTION FENCE RADIUS (Ft.) MAINTENANCE AND PROTECTION Sequoia sempervirens Sequoia sempervirens Sequoia sempervirens Coast redwood Coast redwood Coast redwood /20 90/75 85% Good No? n/a X /20 90/75 85% Good No? n/a X /20 90/75 85% Good No? n/a X Good live twig density and live twig extension. Multiple mainstems in uppermost 5 feet of canopy. Good live twig density and live twig extension. Multiple mainstems in uppermost 10 feet of canopy. Good live twig density and live twig extension. Multiple mainstems in uppermost 20 feet of canopy. Good live twig density and live twig extension. 10 to to to 20 If tree were to be retained, then all competing mainstems would need to be removed at their attachment points, leaving a single vertical mainstem. If tree were to be retained, then all competing mainstems would need to be removed at their attachment points, leaving a single vertical mainstem. If tree were to be retained, then all competing mainstems would need to be removed at their attachment points, leaving a single vertical mainstem. 4 Sequoia sempervirens Coast redwood /20 90/80 88% Good No? n/a Tree appears to have a single vertical mainstem (good). 10 to Good live twig density and live twig extension. 5 Sequoia sempervirens Coast redwood /20 90/85 90% Excellent No? n/a Tree appears to have a single vertical mainstem (good). 10 to of 15

15 Tree Tag Number Genus & Species Common Name Trunk1 Diameter Trunk2 Diameter Trunk3 Diameter Sum of All Trunk Diameters Height & Canopy Spread (Ft.) Health & Structural Rating (100% Each) Overall Condition Rating (0 to 100%) Protected per City of Berkeley Oak Ordinance? (R)emove Tree (S)ave Tree (D)isposition Unclear Severity of Impacts Expected from Site Plan Related Work Multiple codominant mainstems Pests and Disease Presence, and Other Notes SUGGESTED ROOT PROTECTION FENCE RADIUS (Ft.) MAINTENANCE AND PROTECTION 6 Quercus agrifolia Coast live oak /30 85/40 67% Fair Yes? Moderate to Severe (To be determined) X Good live twig density and live twig extension. Bark inclusion type fork at 5 feet above grade is a defect that requires cabling or through-bolt brace installation if tree is retained. At least 8 to 10 separate machinery impacts were noted as scars and branch breakages throughout the lower to mid elevation areas of the canopy, measuring between 4 inches and 6 inches diameter each. 15 feet radius in all directions where possible. If tree is retained, then utilize orange plastic snow fence wrap 20 layers around lower trunk as a protection padding, erect chain link fencing at 15 feet offset from trunk edge, and apply water at canopy dripline per the project arborist to partially mitigate root damages and root loss from excavation and grading. 15 of 15