ArbRpt Winchester 7.19.19
Arborist Report
Winchester Blvd
Campbell, CA
PREPARED FOR
GKW Architects
710 McGlincy Lane, Suite 1
Campbell, CA 95008
PREPARED BY:
HortScience | Bartlett Consulting
325 Ray St.
Pleasanton, CA 94566
July 15, 2019
Arborist Report
Winchester Blvd
Campbell, CA Table of Contents
Page
Executive Summary 1
Introduction and Overview 2
Tree Assessment Methods 2
Description of Trees 3
Suitability for Preservation 4
Evaluation of Impacts and Recommendations 6
Tree Preservation Guidelines 6
List of Tables
Table 1. Condition ratings and frequency of occurrence of trees 3
Table 2. Tree suitability for preservation 5
Exhibits
Tree Assessment Plan
Tree Assessment
Tree Disposition
Arborist Report
Winchester Blvd
Campbell, CA
Executive Summary
GKW Architects is planning the redevelopment of two residential properties, 2575 and 2585
Winchester Blvd in Campbell, CA. Currently the project area consists of two single family homes
with trees in their backyards and front yards. Trees were assessed on May 20, 2019. The
assessment included all trees 6” and greater in diameter, located on or adjacent to the property.
No off-site trees had canopy overhanging the property.
Eleven (11) trees representing eight species were evaluated (Table 1). For all species combined,
trees were evenly split between good, fair and poor condition. One street tree (#32) was included
in the assessment.
On multi-family residential sites, the City of Campbell protects trees with at least one trunk 12”
and greater in diameter (Municipal Code Chapter 21.32 Tree Protection Regulations) and Street
Trees of any size. Based on this definition, there were five Protected Trees and one Street Tree.
These trees cannot be removed without a permit.
Based on my evaluation of the plans:
• 10 trees will be removed (5 Protected)
• 1 tree will be preserved (1 Street Tree)
All on-site trees will be removed in order to construct the site. Construction will take place lot line
to lot line with grading, excavation and hardscape covering the majority of the site. None of the
on-site trees can survive the planned construction.
Australian willow #32 is a street tree located away from the construction. It has a small crown
and is unlikely to experience significant root damage. This is the one tree that can survive
construction. Impacts to trees being preserved can be minimized by following the Tree
Preservation Guidelines.
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Introduction and Overview
GKW Architects is planning the redevelopment of two residential properties, 2575 and 2585
Winchester Blvd in Campbell, CA. Currently the project area consists of two single family homes
with trees in their backyards and front yards. HortScience | Bartlett Consulting was asked to
prepare an Arborist Report for the site as part of the application to the City of Campbell.
This report provides the following information:
1. Assessment of the health and structural condition of the trees within the proposed project
area based on a visual inspection from the ground.
2. Evaluation of the impacts to trees based on development plans.
3. Guidelines for tree preservation during the design, construction and maintenance phases
of development.
Tree Assessment Methods
Trees were assessed on May 20, 2019. The assessment included all trees 6” and greater in
diameter, located on or adjacent to the property. No off-site trees had canopy overhanging the
property. The assessment procedure consisted of the following steps:
1. Identifying the tree as to species;
2. Tagging each tree with an identifying number and recording its location on a map;
3. Measuring the trunk diameter at a point 54” above grade;
4. Evaluating the health and structural condition based on a visual inspection from the
ground:
Good A healthy tree that may have a slight decline in vigor, small amount of twig
dieback, minor structural defects that could be corrected.
Fair Tree with moderate vigor, moderate twig and small branch dieback, thinning of
crown, poor leaf color, moderate structural defects that might be mitigated with
regular care.
Poor Tree in decline, epicormic growth, extensive dieback of medium to large
branches, significant structural defects that cannot be abated.
5. Rating the suitability for preservation as “high”, “moderate” or “low”. Suitability for
preservation considers the health, age and structural condition of the tree, and its
potential to remain an asset to the site for years to come.
High: Trees with good health and structural stability that have the potential
for longevity at the site.
Moderate: Trees with somewhat declining health and/or structural defects that
can be abated with treatment. The tree will require more intense
management and monitoring, and may have shorter life span than
those in ‘high’ category.
Low: Tree in poor health or with significant structural defects that cannot
be mitigated. Tree is expected to continue to decline, regardless of
treatment. The species or individual may have characteristics that
are undesirable for landscapes and generally are unsuited for use
areas.
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Description of Trees
Eleven (11) trees representing eight species were evaluated (Table 1). For all species combined,
trees were evenly split between good, fair and poor condition. One street tree (#32) was included
in the assessment. Descriptions of each tree are found in the Tree Assessment, and
approximate locations are plotted on the Tree Assessment Plan (see Exhibits).
Table 1. Condition ratings and frequency of occurrence of trees
Winchester Blvd, Campbell, CA
Common Name Scientific Name Condition Total
Poor Fair Good
Japanese maple Acer palmatum - 1 - 1
Australian willow Geijera parviflora - 1 1 2
Southern magnolia Magnolia grandiflora - - 1 1
Weeping bottle brush Melaleuca viminalis - 1 - 1
Mulberry Morus alba 3 - - 3
Chinese pistache Pistacia chinensis - - 1 1
Tawhiwhi Pittosporum tenuifolium - 1 - 1
Almond Prunus dulcis 1 - - 1
Total 4 4 3 11
In front of 2575 Winchester Blvd a
southern magnolia with a 15” trunk
diameter was growing. The
magnolia was in good condition
with a strong central leader (Photo
1). An Australian willow in good
condition was growing within the
Public ROW along Winchester Blvd
just east of the property (Photo 2).
In the backyard of 2575 Winchester
Blvd, a weeping bottle brush in fair
condition was large enough to be
included in the assessment.
Several other bottle brushes and
fruit trees were growing in this yard
but were too small to be included.
In front of 2585 Winchester Blvd, a
multi-stemmed Chinese pistache
was growing. It was in good
condition with a small dense crown. A hedge of Tawhiwhi were growing along a patio; one was
large enough to be included in the assessment (#40). Inside the patio, a small Japanese maple
was growing next to the house.
Photo 1 – Southern magnolia #38 was in good condition
growing in the front yard of 2575 Winchester Blvd.
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In the backyard of 2585 Winchester Blvd, three trees had been planted: an Australian willow in
fair condition, a mulberry in poor condition and an almond in poor condition. Mulberry #34 had
decaying cavities; almond #35 had a thin crown and branch dieback. In addition to the mulberry
in the backyard, two mulberries in poor condition were growing on private property near Friar
Way.
On multi-family residential sites, the City of Campbell protects trees with at least one trunk 12”
and greater in diameter (Municipal Code Chapter 21.32 Tree Protection Regulations) and Street
Trees of any size. Based on this definition, there were five Protected Trees and one Street Tree.
These trees cannot be removed without a permit. Protected status of each tree is listed in the
Tree Assessment Exhibit.
Suitability for Preservation
Before evaluating the impacts that will occur during development, it is important to consider the
quality of the tree resource itself, and the potential for individual trees to function well over an
extended length of time. Trees that are preserved on development sites must be carefully
selected to make sure that they may survive development impacts, adapt to a new environment
and perform well in the landscape.
Our goal is to identify trees that have the potential for long-term health, structural stability and
longevity. For trees growing in open fields, away from areas where people and property are
present, structural defects and/or poor health presents a low risk of damage or injury if they fail.
However, we must be concerned about safety in use areas. Therefore, where development
encroaches into existing plantings, we must consider their structural stability as well as their
potential to grow and thrive in a new environment. Where development will not occur, the normal
life cycles of decline, structural failure and death should be allowed to continue.
Evaluation of suitability for preservation considers several factors:
Photo 2 – Australian willow
#32 was a street tree growing
just east of the front yard of
2575 Winchester Blvd.
Photo 3 – Mulberry #41 was in poor condition with a vigorous
crown and decaying wounds covering most of the trunk.
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• Tree health
Healthy, vigorous trees are better able to tolerate impacts such as root injury, demolition
of existing structures, changes in soil grade and moisture, and soil compaction than are
non-vigorous trees. For example, the mulberries were decayed, declining and unlikely to
survive even relatively minor construction impact.
• Structural integrity
Trees with significant amounts of wood decay and other structural defects that cannot be
corrected are likely to fail. Such trees should not be preserved in areas where damage to
people or property is likely. For example, Mulberry #41 had decaying wounds covering
most of the trunk which increases the chances of failure.
• Species response
There is a wide variation in the response of individual species to construction impacts
and changes in the environment. For instance, mulberries tend to be more tolerant of
root pruning than southern magnolias.
• Tree age and longevity
Old trees, while having significant emotional and aesthetic appeal, have limited
physiological capacity to adjust to an altered environment. Young trees are better able to
generate new tissue and respond to change.
• Species invasiveness
Species that spread across a site and displace desired vegetation are not always
appropriate for retention. This is particularly true when indigenous species are displaced.
The California Invasive Plant Inventory Database http://www.cal-ipc.org/plants/inventory/
lists species identified as being invasive. Campbell is part of the Central West Floristic
Province. No species were identified as invasive.
Each tree was rated for suitability for preservation based upon its age, health, structural condition
and ability to safely coexist within a development environment (see Tree Assessment in
Exhibits, and Table 2). We consider trees with high suitability for preservation to be the best
candidates for preservation. We do not recommend retention of trees with low suitability for
preservation in areas where people or property will be present. Retention of trees with moderate
suitability for preservation depends upon the intensity of proposed site changes.
Table 2. Tree suitability for preservation
Winchester Blvd, Campbell, CA
High These are trees with good health and structural stability that have the potential
for longevity at the site. Australian willow #32 had high suitability for
preservation.
Moderate Trees in this category have fair health and/or structural defects that may be
abated with treatment. These trees require more intense management and
monitoring, and may have shorter life-spans than those in the “high” category.
Three trees had moderate suitability for preservation.
Low Trees in this category are in poor health or have significant defects in structure
that cannot be abated with treatment. These trees can be expected to decline
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regardless of management. The species or individual tree may possess either
characteristics that are undesirable in landscape settings or be unsuited for use
areas. Seven trees had low suitability for preservation.
Evaluation of Impacts and Recommendations
The Tree Assessment was the reference point for tree health, condition and suitability for
preservation. I used the Site Plan created by GKW Architects dated February 20, 2019 to
estimate impacts to trees. The plan shows a 15-unit apartment building constructed along
Winchester Blvd along with a parking lot and landscaping.
The disposition of each tree is shown in Tree Disposition attachment. Based on my evaluation
of the plans:
• 10 trees will be removed (5 Protected)
• 1 tree will be preserved (1 Street Tree)
All on-site trees will be removed in order to construct the site. Construction will take place lot line
to lot line with grading, excavation and hardscape covering the majority of the site. None of the
on-site trees can survive the planned construction.
Australian willow #32 is a street tree away from the construction. It has a small crown and is
unlikely to experience significant root damage. This is the one tree that can survive construction.
Impacts to trees being preserved can be minimized by following the Tree Preservation
Guidelines (below).
Tree Preservation Guidelines
The goal of tree preservation is not merely tree survival during development but maintenance of
tree health and beauty for many years. Trees retained on sites that are either subject to extensive
injury during construction or are inadequately maintained become a liability rather than an asset.
The response of individual trees will depend on the amount of excavation and grading, the care
with which demolition is undertaken, and the construction methods. Coordinating any construction
activity inside the TREE PROTECTION ZONE can minimize these impacts.
The following recommendations will help reduce impacts to trees from development and maintain
and improve their health and vitality through the clearing, grading and construction phases.
Tree Protection Zone
1. A TREE PROTECTION ZONE shall be identified for tree #32. The TREE PROTECTION ZONE shall
be a circle around the tree with a radius of 10 feet.
2. Fence all trees to be retained to completely enclose the TREE PROTECTION ZONE prior to
demolition, grubbing or grading. Fences shall be 6 ft. chain link with posts sunk into the
ground or equivalent as approved by the City.
3. Fences must be installed prior to beginning demolition and must remain until construction is
complete.
4. No grading, excavation, construction or storage or dumping of materials shall occur within the
TREE PROTECTION ZONE.
5. No underground services including utilities, sub-drains, water or sewer shall be placed in the
TREE PROTECTION ZONE.
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Design recommendations
1. Any changes to the plans affecting the trees should be reviewed by the Consulting Arborist
with regard to tree impacts. These include, but are not limited to, site plans, improvement
plans, utility and drainage plans, grading plans, landscape and irrigation plans, and
demolition plans.
2. Plan for tree preservation by designing adequate space around trees to be preserved. This is
the TREE PROTECTION ZONE: No grading, excavation, construction or storage of materials
should occur within that zone. Route underground services including utilities, sub-drains,
water or sewer around the TREE PROTECTION ZONE.
3. No clearance pruning should take place on tree #32 without the Consulting Arborist’s and
City’s review.
4. Tree Preservation Guidelines prepared by the Consulting Arborist, which include
specifications for tree protection during demolition and construction, should be included on all
plans.
5. Any herbicides placed under paving materials must be safe for use around trees and labeled
for that use.
6. Do not lime the subsoil within 50’ of tree #32. Lime is toxic to tree roots.
7. As trees withdraw water from the soil, expansive soils may shrink within the root area.
Therefore, foundations, footings and pavements on expansive soils near trees should be
designed to withstand differential displacement.
8. Avoid directing runoff toward tree #32.
Pre-demolition and pre-construction treatments and recommendations
1. The demolition and construction superintendents shall meet with the Consulting Arborist
before beginning work to review all work procedures, access routes, storage areas, and tree
protection measures.
2. Fence all trees to be retained to completely enclose the Tree Protection Zone prior to
demolition, grubbing or grading. Fences shall be 6 ft. chain link. Fences are to remain until all
grading and construction is completed.
3. Fences are to remain until all grading and construction is completed. Where demolition must
occur close to trees, such as removing curb and pavement, install trunk protection devices
such as winding silt sock wattling around trunks or stacking hay bales around tree trunks.
4. Structures and underground features to be removed within the TREE PROTECTION ZONE shall
use equipment that will minimize damage to trees above and below ground, and operate from
outside the TREE PROTECTION ZONE. Tie back branches and wrap trunks with protective
materials to protect from injury as directed by the Project arborist. The Project arborist shall
be on-site during all operations within the TREE PROTECTION ZONE to monitor demolition
activity.
5. All tree work shall comply with the Migratory Bird Treaty Act as well as California Fish and
Wildlife code 3503-3513 to not disturb nesting birds. To the extent feasible tree pruning and
removal should be scheduled outside of the breeding season. Breeding bird surveys should
be conducted prior to tree work. Qualified biologists should be involved in establishing work
buffers for active nests.
Recommendations for tree protection during construction
1. Any approved grading, construction, demolition or other work within the TREE PROTECTION
ZONE should be monitored by the Consulting Arborist.
2. All contractors shall conduct operations in a manner that will prevent damage to tree #32.
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3. Tree protection devices are to remain until all site work has been completed within the work
area. Fences or other protection devices may not be relocated or removed without
permission of the Consulting Arborist.
4. Construction trailers, traffic and storage areas must remain outside TREE PROTECTION ZONE at
all times.
5. Any root pruning required for construction purposes shall receive the prior approval of and be
supervised by the Project Arborist. Roots should be cut with a saw to provide a flat and
smooth cut. Removal of roots larger than 2” in diameter should be avoided.
6. If roots 2” and greater in diameter are encountered during site work and must be cut to
complete the construction, the Project Arborist must be consulted to evaluate effects on the
health and stability of the tree and recommend treatment.
7. Prior to grading or trenching, trees may require root pruning outside the TREE PROTECTION
ZONE. Any root pruning required for construction purposes shall receive the prior approval of,
and be supervised by, the Project Arborist.
8. Spoil from trench, footing, utility or other excavation shall not be placed within the TREE
PROTECTION ZONE, neither temporarily nor permanently.
9. All grading within the dripline of trees shall be done using the smallest equipment possible.
The equipment shall operate perpendicular to the tree and operate from outside the TREE
PROTECTION ZONE. Any modifications must be approved and monitored by the Consulting
Arborist.
10. If injury should occur to any tree during construction, it should be evaluated as soon as
possible by the Consulting Arborist so that appropriate treatments can be applied.
11. No excess soil, chemicals, debris, equipment or other materials shall be dumped or stored
within the TREE PROTECTION ZONE.
Maintenance of impacted trees
Our procedures included assessing trees for observable defects in structure. This is not to say
that trees without significant defects will not fail. Failure of apparently defect-free trees does
occur, especially during storm events. Wind forces, for example, can exceed the strength of
defect-free wood causing branches and trunks to break. Wind forces coupled with rain can
saturate soils, reducing their ability to hold roots, and blow over defect-free trees. Although we
cannot predict all failures, identifying those trees with observable defects is a critical component
of enhancing public safety.
Furthermore, trees change over time. Our inspections represent the condition of the tree at the
time of inspection. As trees age, the likelihood of failure of branches or entire trees increases.
Annual tree inspections are recommended to identify changes to tree health and structure. In
addition, trees should be inspected after storms of unusual severity to evaluate damage and
structural changes. Initiating these inspections is the responsibility of the client and/or tree
owner.
Preserved trees will experience a physical environment different from that pre-development. As a
result, tree health and structural stability should be monitored. Occasional pruning, fertilization,
mulch, pest management, replanting and irrigation may be required. In addition, provisions for
monitoring both tree health and structural stability following construction must be made a priority.
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If you have any questions about my observations or recommendations, please contact me.
HortScience | Bartlett Consulting
Ryan Gilpin, M.S.
Certified Arborist #WE-10268A
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Exhibits
Tree Assessment Map
Tree Assessment
Tree Disposition
Tree Assessment Plan 2575 & 2585 Winchester Blvd. Campbell, CA Prepared for: GKW Architects, Inc. Campbell, CA May 2019 No Scale Notes: Base map provided by: GKW Architects, Inc. Campbell, CA Numbered tree locations are approximate. Trees with no tag number were less than 6” in diameter and not included in this assessment. 325 Ray Street Pleasanton, California 94566 Phone 925.484.0211 Fax 925.484.0596 33 34 35 36 X 37 38 39 32 40 41 42
Tree No.Species Trunk
Diameter
(in.)
Protected
Tree?
Condition Suitability for
Preservation
Comments
32 Australian willow 9 Street Tree Good High Street tree; multiple trunks arise from 4 feet; small, dense crown.
33 Australian willow 10 No Fair Moderate Multiple trunks arise from 15 feet; wide spreading crown; dieback.
34 Mulberry 14 Yes Poor Low Multiple trunks arise from 5 feet with decaying cavity; pollards
decaying; vigorous crown.
35 Almond 13 Yes Poor Low Multiple trunks arise from 4 feet; narrows at graft attachment;
branch dieback; thin crown.
36 Japanese maple 6,3 No Fair Low Codominant trunks arise from 3 feet; small, dense crown; dead
branch; crown one sided away from house.
37 Weeping bottle
brush
9 No Fair Low In raised bed; part of hedge.
38 Southern magnolia 15 Yes Good Moderate Strong central leader; dieback; under utilities.
39 Chinese pistache 8,7,6,5 No Good Moderate Multiple trunks arise from 4 feet; small dense crown; under
utilities.
40 Tawhiwhi 8,3 No Fair Low Part of hedge; crown one sided over driveway; trunk wounds and
rope holding cracked smaller stem.
41 Mulberry 16 Yes Poor Low Multiple trunks arise from 5 feet with decaying wounds covering
most of trunk; vigorous crown.
42 Mulberry 12 Yes Poor Low Multiple trunks arise from 7 feet; poor pollarding; vigorous crown;
decaying roots; wet soil.
Tree Assessment
Winchester Blvd
Campbell,CA
June 2019
Tree No.Species Trunk
Diameter
(in.)
Protected
Tree?
Disposition Comments
32 Australian willow 9 Street Tree Preserve Potential root damage from driveway
33 Australian willow 10 No Remove Within grading
34 Mulberry 14 Yes Remove Within grading
35 Almond 13 Yes Remove Within grading
36 Japanese maple 6,3 No Remove Within grading
37 Weeping bottle brush 9 No Remove Within grading
38 Southern magnolia 15 Yes Remove Within grading
39 Chinese pistache 8,7,6,5 No Remove Within grading
40 Tawhiwhi 8,3 No Remove Within grading
41 Mulberry 16 Yes Remove Within grading
42 Mulberry 12 Yes Remove Within grading
Tree Disposition