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` Heritage Tree Protection Ptan
Brittany Drive Estates, Tract-5073 '
Dublin, CA .
PREPARED FOR:
Black Mountain Development ..
i2 Crow Canyon Ct., Suite 247
San Ramon CA 94583
PREPARED BY:
HortScience, Inc. ~
4126 Mohr Ave., Suite F
Pleasanton CA 94566
February 2001
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CITY OF DUBLIN
- BUILDINC3 INSPECTIpN DEPT.
J4TTAGHN~NT ~' .
Heritage Tree Protection Plan
Brittany Drive Estates, Tract 5073
Dublin, CA
Table of Contents
Page
Introduction and Overview 2
Survey Methods 2
Description of Trees 3
Suitability for Preservation 4
Evaluation of Impacts and Recommendations for Preservation 6
Tree Preservation Guidelines ~
List of Tables and Exhibits
Table 1. Condition ratings and frequency of occurrence for trees 3
Table 2. Suitability for Preservation 5
Attachments
Tree Survey Map
Tree Protection Fencing Plan
Tree Survey Form
Heritage Tree Protec :Plan, Brittany Drive, T. 4073, Dublin HortScience, Inc.
February 12, 2001 Page 2
Introduction and Overview
Black Mountain Development is proposing to develop six lots located on Brittany Drive
and one lot on Rolling Hills Dr. in Dublin, CA. The project encompasses portions on the
native oak woodland. The Tentative Tract map was approved by the City Council of
Dublin in 1985 in Resolution No. 82-85. That document requires preparation of a
horticultural report if project grading is performed within 25 feet of the dripline of trees.
Since that time a Heritage Tree Ordinance (No. 29-99) has been enacted that requires
preparation of a Heritage Tree Protection Plan. HortScience, Inc was asked to prepare
that report. This report provides the following information:
1. A survey of trees within the project boundaries.
2. An assessment of the impacts of constructing the proposed project on the trees.
3. Guidelines for tree preservation and protection during the design, construction
and maintenance phases of development.
Survey Methods
Trees were surveyed in July 2000. The survey included trees greater than 6" in diameter,
located within the project boundaries. The survey procedure consisted of the following
steps:
1. Identifying the tree as to species;
2. Tagging each tree with an identifying number;
3. Measuring the trunk diameter at a point 54" above grade.
4. Evaluating the health and structural stability using a scale of ~ -5:
5 - A healthy, vigorous tree, reasonably free of signs and symptoms of
disease, with good structure and form typical of the species.
4 -Tree with slight decline in vigor, small amount of twig dieback, minor
structural defects that could be corrected.
3 -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.
2 -Tree in decline, epicormic growth, extensive dieback of medium to large
branches, significant structural defects that cannot be abated.
7 -Tree in severe decline, dieback of scaffold branches and/or trunk; most
of foliage from epicormics; extensive structural defects that cannot be
abated.
0 -Dead tree.
Heritage Tree Protec ;`Plan, Brittany Drive, T. 4073, Dublin ~ HortScience, Inc.
February 12, 2001 Page 3
5. Rating the suitability for preservation as "good", "fair" or "poor„. 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.
Good: Trees with good health and structural stability that have the
potential for longevity at the site.
Fair. Trees with somewhat declining health and/or structural defects
than can be abated with treatment. The tree will require more
intense management and monitoring, and may have shorter life
span than those in `good' category.
Poor. 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.
6. Recording the tree's location on a map.
Description of Trees
Twenty (20) trees were evaluated. Descriptions of each tree are found in the Tree
Survey (see Attachments). A summary is provided in Table 1. Tree locations are shown
by tag number on the Tree Survey Map (see Attachments).
The trees on the subject property are a portion of a small woodland associated with a
drainage course south of Brittany Dr. Two oak species were present on the south-facing
slope: the evergreen coast live oak, which comprised 20% of the population and the
deciduous valley aak with 80% of the population (Table 1). Two of the oaks were on a
west-facing slope off Robing Hills Dr.
As is normal for native aak woodlands, a range of tree condition was present, from
excellent to poor. Tree condition ranged from excellent to poor, although most (80%)
were in the good to fair category. Most were large, mature individuals. Tree size ranged
n n
from 14 to 61 diameter single-trunked trees. Average trunk diameter was 28". There
were six multiple-trunked trees with individual trunks ranging in size from 6" to 40".
Table i : Condition ratings and frequency of occurrence of trees at T. 5073
Common Name Scientific Name Condition Rating No. of
Good Fair Poor Trees
(4-5) (3) (1-2)
Coast live oak Quercus agrifolia 1 1 2 4 (20%)
Valley oak Quercus lobafa 7 7 2 16 (80%)
Total 8 8 4 20
40% 40% 20% 100%
Heritage Tree Protec Plan, Brittany Drive, T. 4073, Dublin __ ` HortScience, Inc.
February 12, 2001 Page 4
Heritage Trees
City of Dublin Ordinance No. 29-99 identifies "Heritage Trees" as being any of the
following:
1. Any oak, bay, cypress, maple, redwood, buckeye and sycamore tree having a
trunk of 24" or more in diameter measured 4.5' above natura{ grade.
2. A tree required to be preserved as part of an approved development plan, zoning
permit, use permit, site development review or subdivision map.
3. A tree required to be planted as a replacement far an unlawfully removed tree.
By definition #1,13 trees are Heritage. However, because the project was approved with
the trees at the Tentative Tract Map stage, all trees are now designated as Heritage by
definition #2.
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 the
potential for trees to grow and thrive in a new environment as well as their structural
stability. 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:
^ 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.
^ 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.
^ Species response
There is a wide variation in the response of individual species to construction
impacts and changes in the environment. Coast live oak has good construction,
while valley oak has moderate tolerance to impacts.
^ 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.
Heritage Tree Protec pPlan, Brittany Drive, T. 4073, Dublin ' HortScience, lnc.
February 12, 2001 Page 5
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 Survey
Form). A summary is provided in Table 2.
Table 2: Suitability far Preservation of Trees in Tract 5073.
Good These are trees with good health and structural stability that have the
potential for longevity at the site. Eight (8) trees were rated as having
good suitability for preservation.
Tree No. Species Diameter
335 Valley oak 27, 23, 23
337 Valley oak 25, 16
340 Coast live oak 40, 26
346 Valley oak 31
350 Valley oak 31
352 Valley oak 28
353 Valley oak 19, 18, 15, 13
354 Valley oak 31
Moderate Trees in this category have fair health and/or structural defects that
may be abated with treatment. Trees in this category require more
intense management and monitoring, and may have shorter life-
spans than those in the "good" category. Eight (8} trees were rated
as having moderate suitability for preservation.
Tree No. Species Diameter
(in.)
338 Valley oak 29
342 Coast live oak 41
343 Valley oak 14, 13, 12, 11, 6
344 Valley oak 33
347 Valley oak 25
348 Valley oak 17
349 Valley oak 61
351 Valley oak 17, 13
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 regardless of management. The species or
individual tree may possess either characteristics that are
undesirable in landscape settings or be unsuited for use areas. Four
(4) trees were rated as having low suitability for preservation.
Tree No. Species Diameter
(in.)
336 Valley oak 20
339 Coast live oak 22
341 Coast live oak 15
345 Valley oak 14
Heritage Tree Protec 'r'Plan, Brittany Drive, T. 4073, Dublin HortScience, Inc.
February 12, 2001 Page 6
W e consider trees with good 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 structures will be present. Retention of trees with moderate
suitability for preservation depends upon the intensity of proposed site changes.
Evaluation of Impacts and Recommendations for Preservation
Appropriate tree retention develops a practical match between the location and intensity
of construction activities and the quality and health of trees. The Tree Survey Form was
the reference point for tree condition and quality. Potential impacts from construction
were evaluated using the Composite Site Plan (June 2000) and house layouts for lots 1, 8
and 9 prepared by EDI Architecture, Inc. (received Feb. 12, 2001 }.
Potential impacts from construction were assessed for each tree. The project has been
designed to retain ail trees. Normally we would not recommend retention of trees in poor
condition. However, because this is a native stand of oaks and the trees in poor condition
are downslope from the home areas, they can be retained.
Only trees along the north canopy edge will be impacted by construction. These include
trees #335, 342, 340, 341, 345, 346 and 353. Construction will occur a minimum of 5'
outside the driplines of all trees. Roots of oaks typically extend for a long distance beyond
the dripline. Construction of the homes on lots 1, 7, 8 and 9 will encroach into the root
area. However, we consider the encroachment to be within the tolerance level of the
adjacent trees. We expect no observable reduction in plant growth or health from the
construction. Fill placed outside the driplines years ago when Brittany Drive was
constructed has had no observable effect. No impacts to the trees will occur downslope
from the trunks. A TREE PROTECTION zoNE at the driplines of trees shall be established.
The Wildfire Management Plan contains several requirements that affect management of
the trees:
Pruning is required to, "thin foliage, remove dead wood, raise the foliage one-foot
above the ground, and separate the crowns of the trees." Implementation of
these requirements will be directed by the Fire Marshall, project arborist and
City's arborist. It is unclear at this time how much pruning will be required to
separate crowns of the trees because they exist in small groves of continuous
canopy. Specifications for pruning will be provided following on-site consultation
with the Fire Marshall.
"Ground under the Fire Resistive Heritage Trees shall be kept free of weeds and
dead wood." Weed controls must be applied in a manner that wil! not harm trees.
Pre-emergent herbicides and tilling are not acceptable methods of weed control.
Post-emergent herbicides and hand-pulling weeds are allowable.
"An irrigated fuel breaWgreenbelt sha!! be installed surrounding the Fire Resistive
Heritage Trees." The irrigated area must be designed to protect the native trees
from excessive water and exclude trenching to install irrigation lines within the
TREE PROTECTION ZONE.
The rock outcropping on lot 9 will be removed to construct the home. To eliminate
patentia{ damage to trees on that lot we recommend retaining any rocks in place within
30' of the trunks.
Heritage Tree Protec. ;'Plan, Brittany Drive, T. 4073, Dublin HortScience, Inc.
February 12, 2001 Page 7
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.
Design recommendations
1. A TREE PROTECTION ZONE shall be established at the dripline of all trees. No
grading, excavation, construction or storage of materials shall occur within that
zone.
2. All site development plans shall be reviewed by the Project Arborist for evaluation
of impacts to trees and recommendations for mitigation.
3. Retain the rock outcropping within 30' of trees #335 and 342.
4. No underground services including utilities, sub-drains, water or sewer shall be
placed in the TREE PROTECTION ZONE.
5. Tree Preservation Notes, prepared by the Consulting Arborist, should be
included on all construction plans.
6. Irrigation systems must be designed. so that no trenching will occur within the
TREE PROrecTloN ZONE. Surface water from irrigation runoff must be directed
away from oak trunks.
7. No landscape improvements such as lighting, pavement, drainage or planting
may occur within the TREE PROTECTION ZONE that may negatively affect the health
or structural stability of the trees.
8. 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."
Pre-construction treatments and recommendations
1. Prune trees to be preserved to clean the crown and to provide 1' clearance as
required by the Wildfire Management Plan, and to clear the crown. All pruning
shall be completed by a Certified Arborist or Tree Worker and adhere to the Tree
Pruning Guidelines of the International Society of Arboriculture. Specifications for
pruning shall be provided after consultation with the Fire Marshall. Brush shall be
chipped and spread beneath the trees within the TREE PROTECTION ZONE.
2. Fence all trees to be retained to completely enclose the TREE PROTECTION ZONE
at the driplines as depicted on the Protection Fencing Plan (see Attachments). It
Heritage Tree Protec.. ;'Plan, Brittany Drive, T. 4073, Dublin - HortScience, Inc.
February 12, 2001 Page 8
is not necessary to fence trees on the downhill side, away from all construction.
Fences shall be 6 ft. chain link or equivalent as approved by consulting arborist.
Fences are to remain until all grading and construction is completed.
Recommendations for tree protection during construction
1. Prior to beginning work, the contractor is required to meet with the consultant at
the site to review all work procedures, access routes, storage areas and tree
protection measures.
2. No grading, construction, demolition or other work shall occur within the TREE
PROTECTION ZONE. Any modifications must be approved by the City of Dublin and
monitored by the Consulting Arborist.
3. Spoil from trench, footing, utility or other excavation shall not be placed within the
TREE PROTECTION ZONE, neither temporarily nor permanently.
4. 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.
5. No excess soil, chemicals, debris, equipment or other materials shall be dumped
Or Stored within the TREE PROTECTION ZONE.
6. No tree pruning may be performed by construction personnel.
Maintenance of impacted trees
Native oaks in proximity to homes require regular maintenance. It is recommended that
the future homeowners be provided with a Guide to Maintenance for Native Oaks that
describes the care needed to maintain tree health and structural stability. Occasional
pruning, fertilization, mulch, and pest management may be required. In addition,
provisions for monitoring both tree health and structural stability must be made a priority.
As trees age, the likelihood of failure of branches or entire trees increases. Therefore,
annual inspection for hazard potential is recommended.
HortScience, Inc.
--1,~~~~
N da Matheny
Certified Arborist #WC-0
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