HomeMy WebLinkAbout86-075 Hansen Ranch Genl Pln Amendment Study
CITY OF DUBLIN
PLANNING COMMISSION
AGENDA STATEMENT/STAFF REPORT
Meeting Date: February 2, 1987
TO:
Planning
Commission ~
Staff U
FROM:
Planning
SUBJECT:
PA 86-075 Hansen Ranch General Plan Amendment
Study - Study Session
GENERAL INFORMATION:
I. Purpose of Study Session
The function of this Study Session is envisioned to center on the
following three topics: 1) discussion of actions taken to date concerning
the General Plan Amendment Study, 2) informational presentation by the
Applicant, 3) discussion of the mechanics for processing the General Plan
Amendment and Planned Development Prezoning requests, and 3) discussion of
Draft List of Issues.
At the Study Session, it would be appropriate for the Planning Commission
to hear Staff, Applicant and public comments, and discuss any additional
issues that the Planning Commission can identify at this time. It would
not be appropriate for the Planning Commission to make any decision on
this item at the Study Session.
II. Actions Taken to Date Concerning General Plan Amendment Study
On August 4, 1986, the Hansen Hill Development Corporation, an affiliate
development company of Venture Corporation, filed a formal request that
the Dublin City Council consider authorizing a General Plan Amendment
Study.
The proposal involved the Hansen Ranch property, approximately 147 acres
in unincorporated Alameda County along the western boundary of the City.
The site is west of Silvergate Drive, south of Rolling Hills Drive, and
north of Hansen Drive, generally between the Valley Christian Center
Church and the Hatfield and Kaufman & Broad subdivisions. The Applicant
would like to gain City approval for residential development on the site.
On August 11, 1986, the City Council authorized the requested General Plan
Amendment Study. The authorization sanctioned the preparation of a Study
over the Hansen Ranch property and provided for expansion of the Study to
include additional properties in the Western Extended Planning Area. The
Council's action included direction that the Study include a review of the
Circulation System for the entire Western Extended Planning Area.
On October 23, 1986, the Applicant submitted draft copies of a report
prepared by David Gates & Associates and Wilsey & Ham entitled "Draft
Environmental Planning Study for Hansen Hill Ranch". The Report had been
prepared to facilitate the Applicant's conceptual site planning for the
Hansen Ranch property (see Attachment #1).
As a follow-up to the Council's actions on August 11, 1986, the Planning
Director reported back to the Council on October 13, 1986, regarding the
potential expansion of the Hansen Ranch General Plan Amendment Study. The
Planning Director indicated that Staff had sent letters to all 16 groups
of private property owners; no firm commitments by individuals had been
received. The Council authorized an expanded study area that could form a
contiguous area with the City, subject to the property owners paying for
the cost of including their property in the Study.
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ITEM NO.
3. )
COPIES TO: Applicant
Owner
File PA 86-075
Also on October 23, 1986, the City formally issued authorization to the
terms of TJKM Transporation Consultants and EIP Associates to respectively
commence preparation of the Project Holding Capacity/Area Wide Analysis
Traffic Studies and the Environmental Assessment Study.
As a follow-up to securing authorization for the General Plan Amendment
Study, on November 13, 1986, the Applicant filed a request that DSRSD
initiate an Annexation Study (for fire, water, sewer and recreation
services) for the Hansen Ranch property.
On December 10, 1986, the Applicant hosted a neighborhood meeting at the
Shannon Community Center to obtain neighborhood input and comments early
in the planning process for the site. A list of Items of Concern was
generated at the meeting (see Attachment #2).
The Environmental Assessment Study prepared by EIP Associates was
submitted to the City during the week of December 1, 1986. The Report
from TJKM Transporation Consultants was received in two parts with the
Phase l-A Project Holding Capacity submitted on December 17, 1986, and
Phase l-B Area Wide Analysis submitted on January 9, 1987.
On January 16, 1987, the Applicant submitted conceptual plans for the
property, including: 1) Illustrative Plan, 2) Neighborhood Structure, and
3) Experiential Intent (see Attachment #3).
Staff and the Applicant met on January 26, 1987, to consider and discuss a
Draft List of Issues involving the Hansen Ranch property (see Attachment
#4). The List summarized development constraints identified in the TJKM
and EIP Reports and existing General Plan Policies which pertain to the
site.
III. Summary of Actions Taken to Date Concerning General Plan Amendment Study
Actions which will follow the February 2, 1987, Planning Commission Study
Session on the Hansen Ranch General Plan Amendment Study include the
following:
- Additional neighborhood meetings (including a meeting tentatively slated
for February 18, 1987, at which time the Applicant will present and
discuss conceptual development plans).
- City Council Study Session (if determined necessary).
- Applicant's formal submittal of a General Plan Amendment request and a
Planned Development Prezoning request (may also include submittal of the
Tentative Map application).
- Staff preparation (wih major support work by EIP Associates) of Initial
Study and Notice of Preparation of an Environmental Impact Report (EIR).
- EIR preparation by EIP Associates and TJKM Transporation Consultants.
- Commencement of the public hearing process by the Planning Commission,
then City Council to consider and certify the EIR, and to consider the
General Plan Amendment and Planned Development Prezoning requests.
RECOMMENDATION:
FORMAT:
1)
2)
3)
Hear Staff presentation.
Hear informational presentation by Applicant.
Discuss Draft List of Issues with Staff, Applicant and
public.
Supplement or elaborate on Draft List of Issues as
appropriate.
4)
ACTION:
Based on the above Staff Report, Staff recommends that the
Planning Commission review and discuss the Draft List of
Issues and supplement and/or elaborate the list as
determined appropriate.
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ATTACHMENTS:
1. "Draft Environmental Planning Study for Hansen Hill
Ranch", prepared by David Gates & Associates and
Wilsey & Ham, Civil Engineering
2. Listing of Concerns Generated at Neighborhood Meeting
of December 10, 1986
3. Applicant's Conceptual Development Plans
4. Draft Listing of Issues
-3-
DEVELOPER:
Hansen Hili Development Corporation
187 Bllthedale Ave., P.O. Box 847
Mill Valley, CA 94942
(415)381-1600
CONSULT ANTS:
.; , Da,vlp, Gates, &. A~~oclates. .
2440 Tassajara Lane
Danvllle,CA 94526
(415)837-8176
Wilsey & Ham
6377 Clark Ave., Suite 100
Dublin, CA 94568
(415)828-6755
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Consulting Civil Engineer
John R. DeHorn
Danvllle, CA
(415)831-9351
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17 OCTOBER 1986
Hansen
Hill
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Environmental
Planning _
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REGIONAL. CONTEXT
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The Hansen Hill Ranch property is located
in Alameda County, adjacent to the City of
Dublin. The site is located less than
three miles from the intersection of
Interstate 580 and Interstate 680, the two
primary highways in the county.
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Dublin, a community which incorporated in
1982, is beginning to establish a strong
residential and employment base. Dublin is
uniquely located between the two largest
business parks in Northern California,
specifically Bishop Ranch in San Ramon and
Hacienda Business Park iri Pleasanton. In
1985, Alameda County maintained a 20
percent share of the entire nine-county Bay
Area employment market. The Dublin and
Pleasanton area of the county has attracted
an increasing share of the commercial and
industrial building construction. In 1985,
the Dublin and Pleasanton area accounted
for 25.6% of the county's commercial and
industrial building permit valuations.
Employment opportunities in the Dublin and
Pleasanton areas are numerous and will
continue to increase for at least the next
ten years. In addition the demand for
housing in the area will continue. A July
1986 study by the Association of Bay Area
Governments (ABAG), entitled A~~Qmmodating
R~~ig~ntlgl Gro~th in t~ Sgn Francisco ~gY
AL~g, indicates that the expected growth in
the number of households between 1980 and
2005 will greatly exceed the number housing
units 'currently planned. Dublin is one of
six cities in the county with a projected
housing shortfall exceeding 1,000 units.
'I'hese employment and housing statistics
demonstrate the important role of Dublin in
the regional economy.
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SURROUNDING CONTEXT
The Hansen Hill Ranch si te consists of
approximately 147 acres in Alameda County
located adjacent t6 the w~~tern bbundarybf
the City of Dublin. Current local access
to the property is from Hansen Drive,
Silvergate Drive, and Martin Canyon Drive,
just off Rolling Hills Drive.
The site is surrounded by suburban
development on all sides except the west
boundary. Surrounding properties include
the Hatfield residential development to the
northeast, the Kaufman and Broad single
family homes to the northeast and townhomes
immedia,t,ely adjac~p,t, tp the e.a~t,e~isting I"
residential neighborhoods on Silvergate and
Hansen Drive to the south and southeast,
and the Valley Christian Center to the
south. Currently the properties to the far
northeast and west of the site, owned by
Nielsen and Cronin, are vacant.
PROJECT' DESCRIPTION
The site has been owned by the Hansen
family for over 100 years. The Hansen
family has always intended that the
property would be developed. The family's
desire to proceed with a developed use of
the property is reflected in the fact that
the property is not in the Williamson Act
or under some type of agriculture preserve.
The property is not prime agriculture land
but over the years, the property has been
fenced and used for grazing.
The project objectives are to provide a
very high quality residential development
that will be consistent with the City of
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Dublin's goals for a high quality and well
planned community. Trees, flat lands,
gently rolling hills, views, and open space
all give the property a special character.
The development objective of the site is to
preserve thes~ features where possible, and
provide a site design and architecture that
will be compatible with and enhance the
site's natural features.
At this stage only preliminary concepts for
the site have been e~amined. The applicant
is waiting to submit a detailed plan until
the City has completed on environmental
assessment of the site. In addition,
neighborhood and community input meetings
will be held prior to development of a
~etailed plan. The goal of the applicant
is to then develop a deta'i1'ed sit'e I?lan
which is sensitive to community input and
~esponsive to the environmental' constraints
and opportunities identified in the City's
study.
. Initial concepts for the site have been
developed in response to the City's General
Plan policies and include the following
components:
o
Provision
residential
some homes
lots.
of a mixture of
home types, including
on large and estate
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Creation 0 fan 0 pen
space/greenbel t area on portions
of the existing drainage and
creek areas where major trees
exist.
o
Concentration of development
activities on slopes of less than
30 percent.
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Orientation of the site plan to
preserve and create view
opportunities.
o
Creation of smaller individual
neighborhoods within the site,
utilizing the site's natural
features as buffer areas.
Creation of a sensitive, \,?ell
landscaped 'project entrance.
Other important project elements will
emerge as the site study process continues.
o
ZONING AND PROJECT
REVIEW PROCESS ..
A portion of the site is located in the
Primary Planning Area of the General Plan,
and the other portion is in the Extended
Planning Area. within the,Primary Planning
Area, the General Plan f.iap and Land Use
Element specify the following land use
pol icies:
Residential site No.5, 4 acre,
24 to 32 units, Medium Density
(8+ per acre to match Kaufman &
Broad tentative map mUlti-family
densi ty) .
I 2'~ .., Res Id e 11 t i a I sit e No.6, 7 a c r e, 7 ",
to 20 units, single Family
(allowable density within single-
family range to be determined
based on site conditions).
1.
3. Residential site No.7, 6 acre, 6
to 20 units, Single Family
(allowable density within single-
family range to be determined
based on site conditions).
Wi thin the Extended Planning Area,. the
General Plan Map and LanQ.Use Element
contain more general land use pOlicies, and
the specific requirement that a General
Plan Study be done in order to determine
the location and extent of development in
the ~~t~nded,Planning Area.
The Dublin City Council has authorized a
General Plan Study and the scope of the
City's General Plan Study will be to
evaluate the appropriate uses and policies
for the entire site and to examine
ci rculation in the broader Extended
Planning Area. In addition to the General
Plan study, the project review process will
also require an Environmental Impact
Report, a General Plan Amendment,
prezoning, annexation, site plan approval
and architectural review, and tentative and
final subdivision maps. The total review
process is scheduled for comJ?~etion in nine
to twelve months.
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ENVIRONMENT AL
PLANNING PROCESS
The object of the env ironment planning
process is to weave together the landscape,
site features, and development to form a
pattern in areas suitable for development.
The environmental planning process involves
a technical approach which sorts data of
like kind and implication into meaningful
groupings based on the following
cO)llponents:
1. Yiaugl ~Qn~id~Lg~iQn~ - The
landscape is seen as a visual
backdrop, based on subjective
view-related factors and
f '" 1 im ita t i.o n s p r. e s en t e d by the
existence of roads and'
development nearby. The
landscape is also seen as a
v isual foreground, shaping the
image and feeling of the place.
~n~iLQnm~n~gl ELQQ~~~~~ - The
. landscape' 'is' seen 'a's an "inter- ".
related system, affected by
modification in a chain-reactive
way. Impacts to the more
sensitive components can be
mitigated by careful planning.
2.
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3.
General Engineering Suitability -
The landscape is seen as a
workable medium, with associated
properties and conditions
indicating potentials for a wide
choice of engineering actions.
An understanding of groupings of the
components of the landscape can allow
informed observers to determine how and
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where development should take place. This
component-oriented process on the Hansen
Hill Ranch has had the following steps:
1. Formation of an initial
impression of conditions and
patterns of the landscape.
2. Technically-oriented inventory
and mapping of env i ronmental,
visual, and engineering data.
3. Analytical interpretation of data
to determine potentials and
constraints of the land, value of
landscape zones, and suitability
for development.
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Future Steps in Process
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4.' . Stud~y' of camP'o'site development"
suitability zones. Study of the
implications of development.
5. Synthesis of data to establ ish
conceptual design.
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Design developmel'\t...,th,at...~v.qll,1a tes
concepts based on responsiveness
to suitability zones and
landscape tolerances.
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7.
Generation of Master Plan and
Development Guidelines.
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VISUAL CONSIDERATIONS
The overriding visual image of the Hansen
Hill; Ranch prbper.ty is that of the classic
californian landscape, consisting of
rOlling grass-covered knolls that are tree
covered in steeper places. It is a diverse
visual environment, with zones ranging from
the shady, covered creek environment to
sunny, open knolls.
The Hansen Hill Ranch property is not part
of the dominant western ridge in the Dublin
area. The property is located
significantly below Donlan Point, the
visually significant dominant ridge that
defines the skyline to viewers looking west
from the Dubl in area. A portion of the
property contains a minor ridge which
serves as a visual middle ground with
Donlan Point as the background and the
urbanized City of Dublin as the foreground.
In the visual analysis of the site,
importance has been placed on the "view
from the road" because the greatest number
of people will experience Hansen Hill Ranch
in this way. Duration of views as well as
quality and intensity of the experience are
important visual considerations.
The accompanying, photo<;Jraphs depict views
of the site from selected vantage points in
the vicini ty of the property. The si te is
not at all visible from approximately 60
percent of the surrounding Dublin area.
Portions of the site, however are visible
particularly to the east. Only rarely can
one actually stare at the site. When
moving through the vehicular corridors, the
view is intermittently blocked by trees and
buildings, as well 'as being completely
blocked by landforms in some places. From
distant areas, one can never see the entire
site. From some areas one can see
approximately 50 percent of the site, with
"I the knolls,. .ridges,.. a.nd. upper .rea,che,s o.t
the site being the most visible.
Visual zones on the property itself
represent areas that are distinct visual
units, separated from one another by
topography or vegetation, exposed to
special views, or in a remote location.
The additional photographs depict these
landscape zones, showing the degree of
enclosure by topography and vegetation, as
well as views to distant ridges and urban
areas.
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SITE VISIBILITY DIAGRAM
Hansen Hill Ranch
HANSEN HILL DEVELOPMENT CORPORA nON
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LEGEND
D..- -. _.- Sne Nol VisIble
_ From These Areal
N VegeteUon "'eaa On The SI'e
o . .. .",.-: Orassland Areas On The 5118
I!j Developad Area.
_ _ DomInan' Ridge
... Minor RIdges
-.-- Creeks" Swales
___I Malor Slr..ls
_ Highways
. '\ PhotoQl 8ph Loc811on I
~ Views Of The Site
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TYPICAL CROSS SECTION
Hansen Hill Ranch
HANSEN HILL DEVELOPMENT CORPORATION
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1 SAN RAMON ROo' e FWY 580
SOUTH
Uppep papts of gPassland
and tpee lined swales ape
seen
5
AMADOR VALLEY RD & SAN
RAMON ROAD
All uppep and some lowep
papts of site ape seen-
?5~ of site t is seen
Site visibility
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SAN RAMON RD.. e FWY 580
CENTER
Highest gpassland apeas
ape seen-lowep papts of
site scpeened by tpees-
25~ of site * is seen
6SILVERGATE DRIVE
only highest gpassland
apeas ape seen-l0~ op less
of site is seen
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3 SAN RAMON RD. e FWY 580
NORTH
Tpee coveped nopth papts
of site ape seen-gpass-
land areas paptly scpeened
7 SILVERGATE DRIVE e SITE
Close views of many apeas
on the site
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4 DUBLIN BLVD e SAN RAMON RD..
Uppep papts of gpassland
and tpee lined swales ape
seen-50~ of site ~ is seen
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8 SILVERGATE DRIVE e SITE
Close views of many apeas
on the site
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9 SILVERGATE DRIVE @ SITE
Close vie~s of many apeas
on the site
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1 3 FREEWAY 680
All uppep and some lo~ep
pap'ts of. site ape se'en '
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1 0 AMADOR PLAZA
Upper parts of grassland
and tree lined swales
are seen
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1I0PYARD ROAD e FWY 580
Distant vie~s of. site .
~ LOCATES HANSEN HILL RANCH
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DUBLIN BLVD; @ FWY 680
Only highest grassland
areas are seen t ~5% of
site is seen
1 5 FREEWAY 580
lIiflhl3;st.grass~and areas-
10% or less of site is
seen
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1 2GOLDEN GATE d DUBLIN BLVD;
Y,pper parts of grassland
. . and trees lined swales
are seen
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LEGEND
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, Vegetation Areas
Glassland
SUb-Spaces
Prominent Vista Point
Photograph Location
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1 VIEW LOOKING EAST 2 VIEW LOOKING NORTH 3 VIEW LOOKING SOUTH-EAST 4 VIEW LOOKING NORTH
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5 VIEW LOOKING EAST 6 VIEW LOOKING EAST 7 VIEW LOOKING NORTH 8 VIEW LOOKING NORTH-EAST
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VIEW LOOKING EAST
Site Character
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VIEW LOOKING SOUTH
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VIEW LOOKING WEST
1 2 VIEW LOOKING NORTH-WEST
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13 VIEW LOOKING SOUTH-EAST
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VIEW LOOKING NORTH
2 1 VIEW LOOKING NORTH-EAST
12
14
VIEW LOOKING NORTH
1 8 VIEW LOOKING NORTH-EAST
22
VIEW LOOKING EAST
15
VIEW LOOKING EAST
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VIEW LOOKING NORTH
1 9 VIEW LOOKING NORTH-EAST
23
VIEW LOOKING SOUTH
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20 VIEW LOOKING NORTH-WEST
24 VIEW LOOKING NORTH-EAST
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ENVIRONMENT AL
PROCESSES
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Vegetative Inventory
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The vegetative cover contributes to the
rural and unique character of the Hansen
Hill Ranch. Generally the property is
grass-covered on the flats and tree-covered
on the slopes. The steepest areas, where
cattle have not been able to reach, are
covered with poison oak and other shrubs.
In order to understand the patterns and
dynamics of this vegetative cover each
plant communi ty has been studied. Only
through an understanding of vegetation
dynamics can problems associated ~ith
development be mitigated and a harmonlous
relationship between man and nature be
realized.
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Th e ., f p.llow"i I'}.g.., f~ eld .o!?~ e rv a t ions ..a n~
analysis allow the predlctlon of confllcts
related to development as well as exploring
the potential value of the plant life as a
natural and visual feature.
The predominant plant communities are:
o Annual grassland
o Chaparral
o Oak-Bay Woodland
o Bay-Oak'Woodlahd
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Annual Grassland
The grassland on Hansen Hill Ranch is
composed of plants that are not true
natives of California, but a mixture
of European annuals, inCluding
Fescues, Brome grass, and wild oats,
resulting from early grazing and plant
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introduction. This plant community
occurs along the knolls and ridges,
and in pockets within Oak-Bay
Woodland.
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Generally, chaparral occurs in an area
having a climate that would lead one
to expect a woodland community, but
because of the local soil situation,
forest communities are absent and
replaced by a shrub community. This
plant community of sprouting woody
plants comes in on fire and depends on
fire to continue. At Hansen Hill
Ranch, chaparral occasionally occurs
in small pockets in the Oak-Bay
Woodland.
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CHAPARRAL
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TYPICAL VEGETATION SECTION
Hansen Hill Ranch
HANSEN HILL DEVELOPMENT CORPORATION
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Qgk=-llily, Woodland
Oak-Bay Woodland generally occurs
along the cooler, east and north
facing slopes. These slopes are
generally densely wooded with an
overstory dominated by mature coast
live oaks and bays. Mature buckeye
trees and valley oaks are found in
this zone among immature woodlands of
coast live oaks and bays. The usual
scattered understory of poison oak,
coffeeberry, and various other shrubs
is absent from this woodland zone, due
to grazing as well as the lack of
adequate sunlight at ground level.
LIVE OAKS
'llily,::.Qsk NQQQ.l.gng
Bay-Oak Woodland
riparian zone along
occurs in the
the creeks and
tributary swales. It is a complex
vegetation zone, composed of a wide
variety of plant species. ..including Big
Leaf Maple, California Sycamore,
Willow, Valley and Coast Live Oaks, as
well as the predominant Bay trees.
The understory vegetation usually
associated with riparian communities
is not present. This zone is the most
stable plant communi ty, and provides
protective habitats for many species
of wildlife.
., /
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I BUCKEYES ".
This vegetative pattern is part of a
dynamic system of plant succession that may
occur on a given site or over a period of
time. The grasslands are invaded by the
chaparral, which is in turn, invaded by the
Oak -Bay Noodland, the cl im ax communi ty.
This climax plant community is the final
self-perpetuating plant community that will
15
exist in the area under stable ecological
conditions.
At Hansen Hill Ranch, the great majority of
the trees are of the climax species with
.few..s,it.ua~ions ot...ffl,4cp.essio,'1.c;>f gra,ssland ,"
to chaparral, or chaparral to Oak-Bay
Woodland. Within these climax woodlands
are specific mature ,trees that ,have been
deemed noteworthy for their uniqueness,
size, beau ty, loca tion, or value for study
purposes.
MATURE VALLEY OAK
._ ...11
16
VALLEY OAKS
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VEGETATIVE INVENTORY
Hansen Hill Ranch
HANSEN HILL DeVELOPMENT CORPORATION
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t..:2 - - em:t:~ .
LEGEm
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Creek Zone Inventory
Martin Canyon Creek runs through riparian
Bay- Oa k Woodl and along th e no r ther n
boundary of the property. Its visual
character adds aesthetic value to the site
as well as providing food, shelter, water,
and a circulation corridor for wildlife.
Mature trees grow along significant
portions of the creek banks. Martin Canyon
Creek is an intermittent creek with a
channel of width that varies from three
feet to fifteen feet. Generally its banks
are "steep, . with. s1-o'pes . ranging. from" 2:1 to
nearly vertical. The undercutting of
certain trees and a portion of fence is
evidence of creek bank erosion.
The Hansen Hill Ranch site is drained by
three Isw.ales,whic:h, divide the property into
fairly equal watershed areas. These'
tributary swales are similar to each other
in conf igura tion and vegetative cove r.
Each creek confluence zone has suffered
from over-grazing and trampling, and no
distinct channel exists. Grazing has
prevented understory shrubs from taking
hold. Further up each swale, channels are
deeply incised, with mature trees and
poison oak lining the steep banks where
cattle cannot reach.
A fourth tributary swale enters Martin
Canyon Creek at the northwest corner of
Hansen Hill Ranch. It has an extensive
watershed and a well-defined creek channel
with large, dense vegetation and steep
banks. Most of this watershed occurs off
the property; as such, activity on Hansen
Hill Ranch does not significantly impact
the quality of this swale.
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CREEK CHARACTER
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Vegetation/Creek Zone Analysis
The Annual Grassland and Chaparral areas do
not pr'ese'Il t' a tty-: v'e'ge ta t i ve con s t r ai nts to
development. ~he, Oa~-.Bay aJ;ld BaY"70ak.
tioodland areas, however, are more
sensitive. Woodland areas serve several
functions including:
o Retaining slope stability.
o Absorbing a signif icant quanti ty
of precipitation.
o Providing a valuable wildlife
habitat. In particular the
ecotone edge, where grasslands
meet shrub or woodland plant
communities, provides wildlife
habitat diversity.
o Affording physical and visual
definition for distinct zones on
the site.
o Modifying the climate by blocking
wind or providing shade to allow
people to be comfortable in their
environment.
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The relationship between development and
the integrity of vegetative communities is
an important consideration for this site.
The si te contains som e v egeta tiv e ar ea
which should be preserved in their entirety
because they are of highest value and
sensitivity. The' site' contains other
vegetative areaS which can be partly
conserved in conj unction with allow ing
compatible uses in the area and
incorporating special design
considerations.
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It is projected that the elimination of
cattle grazing on Hansen Hill Ranch ~ould
allow poison oak and other understory
shrubs to return, and plant community
succession to resume, creating a situation
requiring control of the more invasive
plants.
.. I Other vegetation chang''e'S' would ,be related
to ,site development, in particular,
gr ading, f ertil ization, and addi tion of
surface water. Oak trees are especially
sensitive to changes in their environment;
trees slated for preservation would require
special design consideration.
The ecological inventory data has been
interpreted and mapped to show vegetative
patterns, areas in need of preservation,
partial conservation areas, and vegetative
areas suitable for development. Vegetation
data has been analyzed and rated according
to size, quality, composition, and
tolerance to changes brought on by
development. 'Creek Zone 'd~ta has been
analyzed to gain an understanding of
drainage, potential destination points, and
potential areas of special visual interest.
19
VEGET A liON/CREEK ZONE ANALYSIS
Hansen Hill Ranch
HANSEN ....l DEVElOPMENT CORPORA lION
~t
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or h_.. .n. _ _ _".~~ _ _ ~r:ill~
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LEGEND
~ 8.y'0.k Wood...
Oak/B.., Woodtand
~ ....d T... "'0"
'*' Zone or ...,.,...t*
intermittent CI..k
o .......... 0...8.y W.......
TrIM.,., Swa'.
lh:I.llned Ch8mel
Chaparral
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PCOTUNI1
'I~)(m . Edge wlth"gh WldlU. Values
II] Amu.1 ......1...
* R~Jh. Special
O..lgn Conslderallon
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GENERAL ENGINEERING
SUIT ABILITY
The engineering suitability data which is
available to date encompasses the following
general information: slope analysis,
surrounding property ownership and use,
existing road system, water supply, storm
drainage, and sanitary sewer information.
All engineering data presented is
considered preliminary and is subject to
refinement as the site study progresses.
. , '
Slope Analysis
The accompanying map depicts the slope
categories which exist on the Hansen Hill
Ranch. The following table summarizes
slope conditions on site.
SJ..Qn~ Catego.r.imi Acreage Percent
0% to 10% 6 AC. 4%
10% to 20% 43 AC. 29%
20% to 30% 34 AC. 23%
Over 30% 65 AC. 44%
148 AC. 100%
Surrounding Property Ownership
and Use
An ownership map of the land north and west
of Hansen Hill Ranch was prepared. The
undeveloped lands in the Dublin Hills are
in the unincorporated part of Alameda
County and are used primarily for
intermittent grazing. Hany properties are
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listed under Williamson Act Agreements
(Government Code Section 51200, et seg.),
and'ate'thu~ preCluded from consideration
for development in the near future. The
Hansen Hill Ranch property and several
other parcels are not under the Williamson
Act. These areas include the following
properties:
~ lliL..
941-0110-001-5
941-:-0018-003
Owner
Acres 1:!:.::.l.
Hansen
148
3
Blaylock,
Gleason,
Pletcher
)' . ~ "
,
941-0018-004
Blaylock,
Gleason,
Pletcher
194
941-0010-001-1,2
Nielsen
(i2
125
61
48
, I"
941-0010-002
o 85A-190 0-02-1,2
o 85A-:-IOOO-002-4
Nielsen
Nielsen
Gibbs
I I" ,.. '~
Of these, the Nielsen and Gibbs parcels are
neither within, nor contiguous to, the City
limits of Dublin. Only Hansen parcel abuts
both the Ci ty 1 imi ts and the municipal
infrastructure. necessary for development of
the land for residential use.
21
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SLOPE' ANALYSIS
Hansen Hill Ranch
HANSEN tM.l. DEVEl.OPMENT CORPORA t10N
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411... .,_"M ~ ~
Ut- - - c=l,i~h,\,;-::ti
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LEGEND
0.0-''''- 00-00"_.
rum '0-00" _. OO\~W 0- so..
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AGRICULTURAL PRESERVE lANDS
Hansen Hill Ranch
HANSEN HIlL DEVELOPMENT CORPORA lION
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P,oporty Uno
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Existing Road System
i . , ' . .. ~ - : I I"', ' ,. ,
The eastern boundary of Hansen Hill Ranch
parcel abuts directly on to Silvergate
Drive with approximately 615 feet of
frontage. Silvergate Drive is a part of
the Silvergate Highlands development by'
Kaufman & Broad, and is scheduled to be
accepted as a city street in the immediate
future. Martin Canyon Road, also a part of
the Silvergate Highlands development,
presently terminates at the northeastern
boundary of the Hansen parcel approximately
900 feet westerly of Silvergate Drive. It
has a 50 foot right of way. It appears
that the potential extension of Martin
Canyon Road to the site was contemplated.
Connection to, and extension of this street
into the Hansen parcel is presently
controlled by a 5 foot "spite strip" at its
southern terminus, granted in fee to the
County of Alameda on the record map of
Tract 4943. Both Hansen and Betlen Drive
appear on the City map to be anticipated
for further extension westward. However,
in reviewing other recent development in
thearea, the City has restricted any
further extension of these roads to date.
Dublin Boulevard is a County road until it
enters the City approximately 900 feet east
of the eastern line of Valley Christian
Center. This County road portion of Dublin
Boulevard also extends westward to provide
access to the Blaylock parcel. On the
northern boundary of the site, an unpaved
road runs along the northern side of
Martin Canyon Creek, from Martin Canyon
Road, through the Cronin parcel, to the
Nielsen parcel, for which private, non-
.exclusive, .easements.,ex,ist. ".' .. "
Road and circulation patterns appropriate
24
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as part of the development of the site is
still under study and evaluation.
., ,
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Water Zones and Supply
The water supply issues involved in the
development of the Hansen parcel will
requi re careful engineer ing evalua tion.
Two basic elements are essential to supply
water to any development: 1) a source of
water, and 2) the ability to mOve that
water to where it is needed. Water service
to the Hansen parcel would be provided by
Dublin San Ramon Service District (DSRSD)
as an expansion of its present system (to
obtain the water service, the Hansen parcel
would need to be annexed into the
district). DSRSD purchases water from Zone
7 of the Alameda County Flood Control and
Water Conservation District (zone 7), which
in turn acquires the water from the u.s.
Bureau of Reclamation (USBR) at the
California Aquaduct. DSRSD has indicated
that a sufficient supply of water is
available to allow development of the
Hansen parcel.
...,'
Approximately 115 acres of the Hansen
parcel are within the Zone III strata and
thus :can.be served from the present system
(see the map depicting the existing water
system layout). Before the development of
Silvergate Highlands, Bordeaux Estates, and
the Estate Homes project at the county
line, Valley Christian Center began the
Zone III strata by installing a temporary
Redwood tank and a temporary pumping
station with which to raise the water from
Zone III into the valley Christian Center's
~ank. Subsequently, all the above
mentioned development b~caine's'i.Jl:lject' to an
agreement with DSRSD. The agreement
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EXISTING VEHICULAR ACCESS
Hansen Hill Ranch
HANSEN HILL DEVELOPMENT CORPORA liON
~_.....-
n a.tN.. t... 811. HafwWlg ~
400 100 ='.'Tll'I~,W ~.&:~m
LEGEND
_ Existing Rosds
--- Private, Unpaved Road
.. . Church Accass Road
Rastrlcted Access
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HYDROLOGY
Hansen Hill Ranch
HANSEN HILL DEVELOPMENT CORPORATION
=:dO",*.._
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-...- Stream ,:led
_ Marlin Canyon Walarahad Boundary
_____ Limit 01 Sub-basin
Hanlan HID Ranch
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~ ':., ,,~~:. ,~:~:"~\(.7i.~~~ .~.-/ .~!> ansen lane
U. ,. \ <<:"" .,.. .. [~... 1;' r ~ ~~ecu..
'; " '_ '=-, .....', ,\~'~: ;::;'~__-_, " ;.. _\ ~ . II ~~ " 0...... .... 8iie~ . ..
)'~~ '.' ., ~~~ ~~~-;,,-:'~ ~~.~~,.. , ~' 7.,,/ . 21f.-.'d;1 ~...... ,.. ~..~dll..
~I ":~d;J'~)~~"~0.~~~~~~-:;K~~'~'. ~ '. l[r--l~t7 \rl - LEGEND l:m..w ....r.&&::I
y-/~ IJ))~~~,~ ' :i,::r-Q>v y--: ~.""... . " I... , ,.
~~ ~ r:4i~~~~" <~ &.. '::---.."\...~::- ~. ~" \;0;-1 \.... ..:....\ I... · Exlatlng Tank
-~/~/~~'J~)\~ o~~.~ .:~ . \l _~. fSi 0 ~~:~otafl'4lorary
~~. ~ ~. ,.'~ .\ ~~_ "~; r \ \ ......-' ~ _:J. . Exlatlng PUII1l
2::-~'-. ~:--... ::~.....:.::::::-.: -::.:--:::: \ (11: ~\~:~~~----- ~ ~'--J I ~'\',~ \:)J 0 Privata Te!l1Porary
:::~ "........:'-. ......:~ '. ' I ( I )' .1 J s:'I _ \.-.l;( ~~ Pump Station
......~, ........ ........ ....~ ," ,J \ "'/' ZJ..- ~ ~~ y
,:~,,":KV~~~ ~<'"'>< ~-~ ",'Ii'"" "'- ,.: _:,'" ~j':. ---_' 0 ,............
) """"'0........<:::"'-... ?-.~:~ . --~ 0' 0. -~...... ," ,.;)-;-.. 17"liT '
, :....:.'::;:::::~':::..... -..... . >:~, : 'i'( -- . ~." >>; ;::.-::::'-:"',' .', -,-. :~b-':->'::--- .~- ~" . J - Exlatlng Water Main
~~..:::::;:::: ":'0-."'\.' . . ,<[ pt =fa; ~ / / -:;"'--". ,'.. " . ~ ' I ---- Futll'e 12' Water Main
~~~>. ':. .'~ ~)J~~'~~')~<;:?r;;'j~"; ~~;::;'/. p-~'\'~' >\~~,\~., ~~~ ~ t. --=; L ~l~\
~ ~'It, ').' , '--_-::: I I!. \ ...........l " ~ I . Yl1... ~ -............,.,,~ <:ce r 't \J\\ -
~",',',,':, .~ .-' ,I; 'r,.........-......: I -~", "..c.-.(~
~:..",,_..:","\: <,:\::~' :~;:-..,., ~_ ~\ L" ! i 1....\ : )/J i 5?:- .....~~J~~I J" ~~
'.'-- '.':.:'&.:~.~__ :".'" ~ I L-./~'/{NI' ?>, \ !(/l .~--.....&~1-1 /,I,::,:-rlF
" '"';l,'.. "\;,:t~ ,~:- ",' ." ~... ... .~,/;/,;q!-~ I (.' { !<~ (9c".:.l._E.~'~'''.\ ~ r It-:
:::-~.::::- ''':L~'~___,:~;'~ :"'~,. (~::?\L"?,1;~r:-'::'~~~"'" ~\ \71 TJJ ~
~~~~~~~,(~- .......::..<.~~";-;....~.,~~ ~t\.W" -;::":~~\;~l~~\~ ' 'l'?"f 1\1 ~
~",\ '_"'~ "'~~~ ", '....~ ~ ~ - ~~ I :t~ ....--... -."; ~ " ~J~ I rl7V'.
~~~'\\,,-.....:--""~,-.""::---"'~ .... '... ::::--.-...."-............ ", .". .~I/~" '/.'.Jf'.'iI~lr:m ,J. ~~ II '1\
) ':1' \ \, \ ~"..::::.::-~-""""":::. . .... .~~~ ( '~, \.- --:::..r,r \ '.,' /It)... ,
,I \ - -....:~' ... . " . " . -- "
(, (~s........... ......"~~<;_ '. __- ./:. '. jTJ~'""''-''' . . \ r >-I -II 7<
~~")""'~"J'))l\)-' :--..~ ~~;~ 30~{jnk.,. ,," ;-.,'. ..~\\<~ . hI' rill . ., ~ --. -1 1/1 ~
~7JY!'l~/LL~~;::''''''''' \::-....:.r~..~:..;;:,;;~:~=:~..~~.' \. ". .\ \. ,a' ....l; .~ II _ Ooo~~ ~ .~..)}; Wf'R
"" 7/04- . -:0.~~~~' /' ( ). a., \'- 1\ ~ W
\...~I -?~ __ ~~ ~ ~'.,,,, '~::,,:~;<>;.7:('= .... 'CT" !\IL.f ' ~ ..c~
}.:.'_-::v)/ '\\....."0...~ -, ~'}~~~J\~h=~-' /' I~,;;ol. .,'" , "'" ~ U\. ~~
~~ ~ ~~\ ""~~.K!7{~'" , ~ ~
~~~"J~,,,Z~~I\.~ ^(J~~~.! -. i;;d;2,'/::''k'''',\','\;'::', ~_~~~
27
WATER ZONES/SUPPL Y
Hansen Hill Ranch
" Oc'''''' ,...
1100 IlGO
UC.~Q~d.o... III
~~~~~~- r- ~-- ~;II~
cm~J'~,'rl ~.:r..-,,:\..~l
Service Area Zone.c Strata
(Wa'er Pf...ure Zone)
Minimum Elevation Suitable
for Zone 4 T .ok
(Elev.Uon 1015 FI.)
..<.1___0
0110 to 30110 Slope
within Zone 4 SIr ole
Prolorred Zone 4 Tonk Slle
Poaalble Alternale Zone 4
Tonk Sites
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requires that a bonafide, permanent Zone
III reservoir, pumping stations, and
pipeline network be constructed to provide
a proper level of water service to the Zone
III strata, and that the Center's temporary
facilities would be dismantled. At the
present time, there remains to be completed
a 12 inch main connection from the Zone II
tank near the end of Betlen Drive, across
the Hansen parcel to an existing 12 inch
stub on the north bank of Martin Canyon
Creek, and a pumping station at the Betlen
D ri vet a n k . Th e 10 cat ion 0 f t his m a i non
the Hansen property has not been
determined.
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There are, however, approximately 33 acres
which lie above Zone III, requiring Zone IV
facilities to be constructed before water
can be moved to serve that area. A map
show in.gthe ,potential water Zone IV is
included. Based on standards of max{mu~
and minimum static pressure requirements
mandated by DSRSD, a tank site at a minimum
elevation of 1015 feet will be required.
The nearest suitable site lies
approximately 1700 feet west of the Hansen
parcel on a secondary ridge in the Blaylock
parcel. Possible alternate tank si tes are
also shown. A suitable pumping station and
pipeline would also be required.
Further discussions with DSRSD and the City
of Dublin will be needed to determine a
final water zone IV proposal.
Storm Drainage
Most of the Hansen parcel lies in the
Martin Canyon drainage basin, which
contains approximately 870 acres upstream
of Silvergate Drive, and consists of five
~q. I
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sub-basins (see map of drainage basins).
Preliminary investigations reveal that in
its present state of development, the 870
acre basin produces a. runoff at Silvergate
Drive equivalent to approximately 89% of
the capacity of the culvert under
Silvergate Drive, based on a "15 year
storm", which is specified by Zone 7 for
design of this type of facility. However,
when the extent of potential development in
the basin becomes determinable, an
evaluation of basin runoff based on a fully
developed state will be required to
ascertain the extent of flooding, if any,
which p 100 years storm would create. This
procedure is mandated by the Federal
Emergency Management Agency (FEMA). The
results can then be used to establish creek
setbacks and any mitigation measures deemed
necessary. (Source: Wilsey and Ham).
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Sanitary Sewer System
The existing sanitary sewer system provides
adequate capacity at relatively convenient
service connection points in Silvergate
Driv'e 'arid along the eastern 900 feet of the
northern boundary to service most of the
parcel. However, there are about 12 acres
in the southwest portion which cannot be
conveniently sewered by gravity to those
connection points, because they slope away
from the Martin Canyon basin. One
possibility is to use a lift station to
convey this area into the rest of the
system. A second possibility would be to
arrange to extend the existing sewer in
Valley Christian Center, if agreeable.
Further evaluation of sanitary sewer
requirements will occur as the study
progresses.
29
EXISTING SANITARY SEWER SYSTEM
Hansen Hill Ranch
HANSEN HILL DEVELOPMENT CORPORATION
~
0100 :roo
--
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,,"""0<...... JIIIIIII!!'!l!I
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tOO 100 r:.~~~ft'fJJi r.o.~~hw.:i
LEGEND
_ PIpe
Menhole
Dltectlon 01 Flow
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HANSEN HILL RANCH
INITIAL COMMUNITY MEETINGS
I. Summary of Comments Received at Community Meeting Held
December 10, 1986
Attendance: Approximately 30 to 35 residents, primarily from Hansen
Drive, Silvergate Drive and Rolling Hills Drive.
,
Summary Comments/Issues as Recorded on Charts at Meeting:
*
*
*
*
*
*
*
Views (views of Mt. Diablo)
Privacy
Solar access
Traffic on Dublin and San Ramon Blvds.
Fire protection
Protection of property values, preference for expensive homes
Questions on density and size of lots (neighborhood wants to
see more detailed plans)
Potential problems with people near creek (i.e. li~~er & noise)
Save the trees
Drainage? Increased creek flows?
Neighborhood impact of extending Martin Canyon Road
Traffic impact on Martin Canyon Road
Increased load on Nielsen School
Fire house location
Need for an EIR and traffic study
Issue of another water tank?
Some comments opposing any development in western a=ea
Strong comments not to extend Hansen Drive
Some comments not in favor of townhouses
*
*
*
*
*
*
*
*
*
*
*
*
II. Summary of Comments Received at Meeting with Adjoining Land Owners
Attendance: Individual meetings/discussions held at va=ious times
with representatives from the Cronin, Nielsen, Blaylock & Gleason,
Kaufman & Broad, and Valley Christian Center properties.
Summary of Major Comments/Issues:
* Access to properties west and north of Hansen Hill Ranch
* Joint access potential at Valley Christian Center and Blaylock
& Gleason properties
* Slope easements for grading
* Sensitive design of property boundaries
* possible trail linkages
* Sewer line placement on Hansen Ranch site
* Joint planning for water service
M ~'? '-\ ~l' 1~ .rt~T 2
~. .~.. ~:. \I." of., .'-... .:1.. r... ,.ii.t ~... ~... ~ ~...'" '. , _
l ,1 il r.,~, .", ,-.,,~ J .
~..~ & ~ if~'~~ ai'll...
~A1f/IeNT5 ~~{Vf fi~r #t11tll~II(;(JIJ
APeilNer
H~NSEN HILL RANCH: DESCRIPTION OF PRELIMINARY CONCEPT PLANS
January, 1987
Project Background
Site Location: The site consists of approximately 147acres in Alameda
County located adjacent to the western boundary of the~City of Dublin.
Current access to the property is from Silvergate Drive, and Martin
Canyon Drive, just off Rolling Hills Drive. Surrounding properties
include the Hatfield single family homes to the north; Kaufman and Broad
single family and townhomes to the north; existing residential neighbor-
hoods on Silvergate and Hansen Drives; vacant properties of Nielsen,
Cronin, and Blaylock & Gleason to the north and west; and the Valley
Christian Center to the south.
Project Goals: The Hansen Hill Development Corporation, which is an
affiliate development company of Venture Corporation, is currently in
contract with the owners of the property to purchase the Hansen Ranch.
The terms of this agreement allow the Hansen Hill Development
Corporation to process a deve~opment application for the property in
cooperation with the owners.
The general project goals are to provide a very high quality residential
development on the site. The site contains a special character with its
trees, flat lands and gently rolling hills, views, and open space. The
applicant's goal for the site is to preserve the site's natural features
where possible and provide a site design and architecture that will be
compatible with the site's special character and that will enhance the
surrounding neighborhoods.
Planning Process
The Hansen Hill Development Corporation and it's design team are
conducting an extensive site analysis and collaborative process prior to
submitting a specifc planned unit development application which is
scheduled for late February, 1987. Many times an applicant submits a
plan and then begins the various studies and coordination meetings. In
this case, because of the site's special features, known community
interest, and the fact that some of the site is not currently addressed
in the City's General Plan, it.was felt that early community input on
the plan would result in a better plan. The planning process being
followed can be summarized in ~he following phases:
Phase I, Detailed Site Analysis and Environmental Planning Study: In
this phase, the Hansen Hill Ranch design team conducted a thorough site and
area analysis. The enclosed Environmental Planning Study, Hansen Hill
Ranch, dated October 17, 1986, summarizes the findings of this phase.
This study identifies important site features and defines the site's
character.
1
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Phase II, City Consultants Prepared Environmental Assessment: In this
pnase, ,the Clty of Dublln retalned lndependent consu.J.tants, EIP and
TJKM, to conduct a site environmental assessment and traffic analysis of
the site and area. These reports are available in the Planning
Department. The findings of these studies were discussed with city
staff and the consultants and the information provided was taken into
consideration in the concept planning for the site.
Phase IlL, Initial Neighborhood Meetings: In this phase, the HanSen
Hill Development Corporation met with residents and property owners in
the area. In December, a community meeting was held primarily for
nearby residents on Hansen Drive, Rolling Hills Drive, Martin Canyon
Road, and Silvergate Drive. In addition to the December community
meeting, other coordination meetings were held with adjoining land
owners including representatives from the Cronin property, the Nielsen
property, the Blaylock & Gleason property, and the Valley Christian
Center. All of the meetings were helpful in defining important
neighborhood issues. Additional neighborhood meetings will be held as
needed throughout the remaining phases of the planning process.
Phase IV, Development and Review of preliminary Concept Plans: Based on
all of the input and information contained in Phases I through III, the
Hansen Hill design team proceeded to develop Concept Plans for review.
These Concept Plans will be reviewed with City staff, the Planning
Commission in study session, and area residents and property owners.
The Planning Commission study session on February 2, 1987, will be the
first review of the Concept Plans. A community meeting to review the
concept plans with nearby residents is scheduled for February 18, 1987.
Phase V, Submittal of project Application: Upon consultation with the
various groups about the preliminary concept plans, the design team will
finalize the Hansen Hill Site Plan and submit a detailed General Plan
Amendment/Pre-Zoning/ and Annexation Application, as well as a PUD
Application and a Tentative Map.
Phase VI, preparation of an Initial Study and An Environmental Impact
Report: The City's consultants, under the dIrection of the City staff,
will then prepare an initial study to define the topics in the EIR and
then proceed with preparing an EIR.
Phase VII, Public Review Process on EIR and Project Application: Public
meetings and hearings will be held on the EIR and the project
application by both the Planning Commission and City Council, resulting
in a project decision.
2
~
The general schedule for each phase is as follows:
Phase 1,11,& III - September t~ru December, 1986
Phase IV - January and February, 1987
Phase V - late February, 1987
Phase VI - March - May, 1987
Phase VII - June - August, 1987
Some variations in this schedule may occur.
Major Issues Influencing the Design Concepts For Hansen Hill Ranch
The Environmental Planning Study for the site, the City's Environmental
Assessment, the City staff's list of issues and the list of issues
generated at community meetings, al: identify important issues, and many
overlapping issues to be considered in the design of the Hansen Hill
Ranch.
At the concept plan stage, it is no~ possible to address all issues in
finite detail. At this concept sta~e, however, there are certain major
issues that have been defined and ge~eral design guidelines for the site
have developed to address these issues. Some of the major items are
li$ted below:
ISSUES
PRELI~INARY
HANSES HILL RANCH
GENER~L DESIGN GUIDELINES
Preservation of Martin
Canyon Creek Zone and
Tributary Swales
* Preserve natural character of creek and
swales, where possible, focusing on the
riparian zone and swales.
* Esta~lish a creek and swale setback and
buf=er zone.
* Enhance/rebuild and/or extend swale
areas where appropriate.
* Utilize creek system as a visual and
useable amenity.
* Revegetate creek and stabilize bank
where appropriate.
* Min~~ize creek crossings.
3
Preservatio_n' of Trees,
vegatation; Wildlife
Areas, and ,Open Space
* Identify major trees for preservation
anc trees where thinning is appropriate.
* Es~ablish a hierarchical value of vege-
ta~ion on site.
* Place development such that major trees
are protected.
~
* Recognize both the vegetative and visual
values of major oak-woodland areas, and
preserve where possible.
* Create an open space/greenbelt system
linking many portions of site.
* Create a wildlife corridor on-site.
Minimize Development
on 313% Slopes
* Re=ognize that the site i~ constrained
by having 44% of site in over 313% slope.
* Mi~imize development on a~eas over 313%
slope and consider development on slopes
over 313% only where unique circumstances
apply.
Design with Full Con-
sideration for Site's
Landslide and Erosion
Potential
* Co~duct detailed geotechnical studies
in=luding an evaluation of potential
la~dslide areas.
* Review potential landslide areas and
de~ermine level of significance, if any
anc determine whether repair or avoidance
is appropriate.
* In=orporate standard engineering and
geotechnical measures into project
design, as required.
Address Si~e Run-off
and Drainage Issues
* Design site plan based on natural
drainage patterns.
* Co~duct a drainage study of Martin Can-
yon Creek and incorporate appropriate
drainage mitigation measures.
4
provide Adequate
Vehicular and
Emergency Access
Protect and/or
Enhance Views and
Visual Quality
* Provide main access on Silvergate Drive.
* Avoid access from Hansen Drive, based on
neighborhood input.
* Consider secondary access, (besides
Silvergate Drive) possibly coordinating
with Valley Christian Center or the
Blaylock & Gleason property.
~
* Consider access on Martin Canyon Road
for emergency purposes only, to minimize
neighborhood and creek disruption.
* Provide traffic mitigation at the inter-
section of Dublin Blvd and San Ramon Blvd
if traffic studies conclude improvements
are needed. .
* utilize private roads in select areas of
site.
* Preserve key views of adjoining
residents, where possible, by utilizing
buffers, landscaping, decorative walls,
or grade separations.
* Preserve major area views of Donlan
Point and Mt. Diablo.
* Maintain oak woodland as a visual
struc ture .
* Minimize grading on steep slopes and
major tree removal (see above).
* Preserve natural knolls or vista areas
where possible; if knoll modification is
required, resculpture and build area
with natural screening or sensitive de-
sign response.
,..
* Minimize development visibility from
scenic highways and from 1-580 & 1-680.
* Create a balance of open view areas and
developed areas on site, and provide
view corridors.
5
* Utilize high quality design and
a~chitectural standards (see below
also) .
* Design the most visible architectural
~lements to recede into the landscape,
utilizing low spreading forms, muted
colors and heavy landscaping.
Housing Mix/Sense of
Neighborhoods/Property
Values
* Provide a mix of housing types
cpnsistent with Dublin's General Plan
gbals.
* Provide a predominance of single family
detached homes of a si ze and style tha t
will enhance the existing residential
a~eas and strengthen property values.
* Coordinate design and landscaping
closely on all sides of the property
with the adjoining uses and with sensi-
tivity to compatability and privacy.
* Create individual high quality neighbor-
hoods within the site, each with its own
s_ense of place.
* Link neighborhoods with a system of open
spaces, paths, and places, to create a
social unity.
High Quality Design
and Architecture
* Create a prominent entrance on site ---
signifying arrival at a special place
and utilizing the existing creek and
vegetation to set the tone and
character.
* Create a central place as a social focus to
the neighborhood.
* Use variable setbacks to provide an
interesting streetscape.
* Use varying facade materials and
building heights to introduce variety.
* utilize classic detailing and fine
architecture to create a sense of high
quality and timeless character for the
area.
6
Infrastructure
Requirements
* Coordinate with the appropriate public
agencies to address the necessary
infrastructu~e requirements for
* Sewer
* Water
* Fire
* Schools-
* Parks
Other issues, including but not limited to nQise, fiscal considerations,
and impact on adjoining agricultural lands will be addressed in ~ore
detail at later stages. In addition, more s~ecific design guidelines
for the above issues will also be formulated~
Hansen Hill Ranch Concept Plan
As can be seen by the various studies and issues, the site offers both a
complex set of elements to be addressed and also many opportunities for
the creation of a special residential area in western Dublin. As in any
site planning process, trade-offs must be considered in order to obtain
a balance of site preservation and site useability.
The following three preliminary concept diag~ams for Hansen Hill Ranch
are enclosed for review:
*
Neighborhood Structure
*
Experiential Intent Diagram
*
Illustrative Plan
The preliminary concept plans show numerous individual neighborhoods
tucked away in various portions of the site, with each neighborhood
creating its own character and charm and each area including major open
space and preservation of natural features. <
At a later stage architectural designs for the project will be ~rovided
which will be compatible with the site's natural features and cc~tribute
to the creation of long lasting character for the area.
In the preliminary concept plan the housing types are as follows:
Area 1: Townhomes with a creekside design orientation; this location
for townhomes was selected because a portion of the area is
already designated in the General Plan for medium densisty
residential use and it is adjacent ~o the townhomes uncer
construction by Kaufman and Broad; ~he townhome area will be
7
.
Area 2:
Area-- 3:
Area 4:
Areas
5,6,11:
Areas
7,8:
Areas
9,lfiJ:
separated from the existing Hansen Drive residents by lcwering
grades and other screening techniques such that Hansen ~rive
views will not be blocked.
Single family homes on lots generally equal to or large= than
the lots on the adjoining Hansen Drive; this area will also be
separated from the existing Hansen Drive residents by lowering
grades and other screening techniques such that Hansen ~rive
views will not be blocked.
This area will consist of either zero-lot-line homes or smaller
patio style homes. The homes will be detacheq homes bu~
clustered closer together. ~
Single family homes with an average lot size:of 12,000 sq.ft.
ranging from 9,000 - 24,000 in lot size.
Single family homes with either a creek amenity or over:ooking
preserved riparian areas.
Single family homes varying in lot size from l0,000 to 35,000
sq. ft. with an average lot size of 20,000.
Custom and semi-custom home areas with varying lot sizes.
In summary, approximately 290 homes are included in the preliminary
concept plan, including 40 townhomes and 250 single family homes. Lot
sizes will range as follows: approximately 5,000 sq.ft. for the :imited
number of patio homes; 7,000 to 12,000 sq.ft. for the medium to :arge
lots; and an average of 20,000 sq.ft. for the largest semi-custo~ lots
in the upper portions of the site, with some lots providing 35,030
sq.ft.
The overall site density for the site is considered very low wit~ an
average of 1.9 to 2.0 units per acre, on the entire 147 acres. :'he site
does not lend itself to a traditional uniform subdivision layout that
would encompass most of the site. Therefore, the development areas have
been clustered in various suitable portions of the site, with ex~ensive
open space areas remaining. In the preliminary conce~t plans, 0= the
147 acres, approximately 60 acres (41%) have been left in open s?ace.
The preliminary concept plans discussed herein will be further refined
based on comments received during Phase IV of the process and prior to
submittal of the detailed project application.
c
8
, ~
'.
~
Developer and Consultant Team
Developer History: The Hansen Hill Development Corporation iS'an
affilia~e development company of Venture Corporation. Venture Corpora-
tion has been in land development in California since 1975. The firm
has primarily been involved in residential projects, as well as mixed-
use and commercial projects. Recent projects of Venture Corpo~ation
include the following: wildflower, 62 homes in Pleasant Hill under
construction; Las Brisas, 230 completed homes in Santa Clara and the
recipient o~ the National Association of Home Builders (NAHB) award for
the outstanding Real Estate Development of 1982; Cote d'Azur, 60 com-
pleted condominium units on the water in Sausalito; and a 1,600-acre
master planned mixed-use community currently in the planning process in
Marin County. The principals of Venture Corporation, prior tq joining
the company, have also been involved in other projects in bot~ Alameda
and Contra Costa Counties.
Consultant Team: Hansen Hill Development Corporation is pleased to have
assembled a team of professionals with excellent design credentials and
a strong knowledge of Dublin's policies and planning requirements.
The Hansen Hill Ranch design team includes the following:
David L. Gates & Associates - Site Design, Site Planning, Landscape
Architecture
Chris Craiker and Associates - Architecture
Wilsey and Ham - Civil Engineering and Infrastructure Planning
John DeHorn - Civil Engineering and Infrastructure Planning
Harding Lawson & Associates - Geotechincal Engineers
More detailed credentials of the design team will be submitted under
separate cover.
9
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Hansen Hill Ranch
DEVELOPMENT CORPORATION
a
'0 . 100200
L.andscape . Architecture II
Urban Design ,
Site P!al)l1ing' '~ III."
I.: ~ .,
2440 Tassajara Lane. Oanvie Ca&l Dl'MDLGATES
Phone 415 837 8176 . 94526 &.ASSOCIATES
15 January 1987
400. . 800
EXPERIENTIAL INTENT DIAGRAM
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CITY OF DUBl-IN
HANSEN
H ILL
List of Issues
(February 2, 1987)
,
1.
GEOTECHNICAL STUDIES
1.1 Site Geology
A. Need to prepare a Preliminary Geologic Hazards Report. Any other
facility that could create a geologic hazard, such as a road or a
building on hillside terrain, must also be covered by such a study.
Each of the hazards described in the Seismic Safety and Safety
Element of the General Plan must be evaluated. This hazard analysis
shall be prepared by a registered Engineering Geologist (see
Sections 8.1.2 (A) and (B) of General Plan).
B. Presence of steep gullying on the north-facing slopes due to
erosion.
C. Presence of landslides on up to 1/3 of 148 acre site (ranging from
"historic" to "active" - based on EIP's preliminary field survey).
D - Slide avoidance of repairs required.
E -
Determination/classification of
following categories is needed:
4) inactive, and 5) topographic
slides into one or more of the
1) deep, 2) shallow, 3) active,
feature unrelated to slides.
1.2 Soils
A. Parent soil materials present are, "soft" and prone to local
landslides.
B. Parent soil materials are prone to high post-construction
settlement, high deformity and hi~h shrink swell potential
(potential impacts to foundations, roadways and utilities - dictates
soils to be amended or removed - ~see Section 8.1.2 (D) of General
Plan) .
C. Loss of soils well suited for grazing (non - "prime" agricultural
soils - only portion of site 7% to 15% slopes).
-1-
, 1lI..~ ...":'I!!,,\ "',.,.., 'I
A~~ .~ ~r'~ '''.''. n. ....:;.i. ".1 .i' -
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1.3 Hydrology
A: Martin Canyon Creek is a deeply incised channel with extensively
eroded creekbanks (90' drop in 4,800' , or 2%).
B. Side gullies are deeply incised and sparsely vegetated - runoff will
flow at high velocities and contribute to further channel/gully
erosion.
.
Need to regulate development to m~n~m~ze runoff by preserving
woodlands and riparian vegetation (see Section 8.2.3 (A) of General
Plan).
C.
D~
Ability of Martin Canyon Creek to handle l5-year storm flows.
E. Need to supply vehicular access for ACFC & WCD - Zone 7 mainentance
(continuous or at discrete intervals) (see Section 8.2.3 (A) of
General Plan).
F. Steepness of channels direct observance of greater structure
setbacks (40' to 50').
-
G. Need for creek stabilization at discrete sections along creek.
H. Need to reduce creek flow velocities to less than six feet per
second (drop structures?).
I. Need to supply drainage studies of entire watershed and to provide
assurance that appropriate mitigation measures will be completed as
needed prior to approval of development (see Section 8.2.3 (D) of
General Plan).
2. VEGETATION AND WILDLIFE
A. Direction to "preserve oak woodlands, riparian vegetation and
natural creeks as open space for their natural resource value" (see
Sections 7.1 (A), 7.3 and 8.2.3 (D) of General Plan).
B. Direction requiring maintenance of open stream corridors of adequate
width to protect all riparian vegetation, improve access to stream
and prevent flooding.
C. EIP direction to provide 30-foot m~n~mum width riparian corridor to
prevent flooding and protect riparian corridor (see Section 7.1 (D)
of GeneralPlan).
if. Need to identify individual trees proposed for removal.
E. Need to secure Department of Fish and Game Streambed Alteration
Permit.
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F. Issue of retention of native bunchgrass areas in a contiguous open
s~ace corridor.
G. Need to revegetate sections of creek (with species characteristic of
local riparian vegetation) where construction requires streambed
alteration (see Section 7.1 (E) of General Plan).
H. Need to maximize wildlife habit values in post construction layout
by making open space areas contiguous with sufficient width and
buffer to new development.
~
3. VISUAL:QUALITY
A. Need to preserve and/or enhance site characteristics with aesthetic
value (knolls with panoramic views, land forms such as significant
ridgelines, water features and site vegetation, such as tree
groupings and grassland).
B. Direction to restrict grading and means of access for the siting of
residential proposals such that they will not disfigure ridgelands
($ee Section 2.1.4 (2) of General Plan).
C. Direction for preservation of oak woodlands, riparian vegetation and
open space (see Section 3.1 (A) of General Plan).
D. R~quirement that steep slopes and ridges be preserved as a condition
of the Subdivision Map approval process (see Section 3.1 (C) of
General Plan).
E. Restriction on placement of structures on the hillsides from
projection above major ridgelines - tying back to concept of a
freestanding City ringed by hills (see Section 3.3 (E) of General
Plan).
F. Direction that the Subdivision and Site Design Review Processes be
utilitzed to assure preservation or enhancement of ridge lines that
form the skyline as viewed from freeways or major arterial streets
(~ee Section 3.3 (F) of General Plan).
G. Need to Protect quality of view from scenic highway.
4. SLOPE ANALYSIS
A. Largest percentage of site falls into slope category in Excess of
30% (65 of 148 acres).
B. Approval of residential development in the Extended Planning Area
requires that proposed site grading and means of access will not
d~sfigure the ridgelines (see Section 2.1.4 (A) of General Plan).
-3-
C. Direction that slope predominantly over 30% will be maintained as
permanent open space for public health and safety (see Section 3.1
(B) of General Plan).
D. Direction to reserve steep slopes and ridges as open space (see
Section 3.1 (C) of General Plan).
E. Restriction of placement of structures on the hillsides that appear
to project above major ridgelines (see Section 3.3o(E) of General
Plan).
F. Direction that, through the Subdivison and Site Review processes,
preservation or enhancement of ridgelines that form the skylines as
viewed from freeways or major arterials will occur (see Section 3.3
(F) of General Plan).
G. Regulation of grading and development on steep slopes (see Section
7.2 (B) of General Plan).
H. Restrictions on development on slopes of over 30% (see Section
7.2 (F) of General P+an).
I. Direction to dedicate the steep slopes (through land planning
design) to land uses 'which do not require extensive construction
(such as common open space, hiking areas, vegetative buffers,
wildlife habitat, presentation of natural drainage and viewpoints).
J. Direction for avoidance of soil color contrasts due to grading in
visually prominent zones (i.e., removal of "A" soil horizon).
5. NOISE
A. Presence of strip of land at south boundary (0' to 400' in width)
which is anticipated to be exposed to noise levels in excess of 60
dBA (per Land Compatibility Table). This area lumped into category
"Conditionally Acceptable for Residential Uses".
B. Additional acoustic analysis is necessary.
C. Installation of special noise attenuation features anticipated as
being necessary (ins~lation and special windows).
6. ARCHAEOLOGICAL RESOURCES
A. Follow State regulations regarding discovery of archaeological sites
and historic resources.
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7. PUBLIC SERVICES
7.1 Water
A. Portions of Site (33! of 148 acres) are not in the Zone III Water
Pressure Elevation Strata and would require establishing a new
service zone.
B. Annexation to DSRSD for water service is required.
C. Development constraints tied to locating and constructing l2-inch
water main connection to establish Zone III loop (from Zone III tank
at Betlen Drive to l2-inchstub on north bank of Martin Canyon
Creek) and an ancillary pump.
D. Obtain DSRSD input and direction for new water zone (i.e., elevation
range to be served, tank location and sizing, etc.).
7.2 Sewer
A. Portion of site (12! of 148 acres) presents special sewer service
problems (southwest portion of site).
B. Annexation to DSRSD for sewer service is required.
7.3 Fire
A. Development of homes in upper boundary of site anticipated to be
beyond five-minute response: test for fire equipment (only eastern
1/3 of site anticipated to be within reaches of the five-minute
response). Special precautions against fire (sprinklers, fire
retardant roof materials, spark arrestors, water storage, vegetation
clearance, etc.) are anticipated to be necessary (see Sections
8.2.2 (A) and (B) of General Plan).
B. Gradient of interior road network must satisfy Fire District's needs
for turning radii, sizing and location of turn-around areas,
provision of a loop circulation system (second way in).
C. Annexation to DSRSD for fir~ protection service is required.
D. Need to prepare Fire Service Study to determine whether a new fire
station, or a modified location for an existing station, is
necessary to provide adequate fire protection in Western Extended
Planning Area.
-5-
7.3 Schools
A. With 575+ homes currently approved for construction, school capacity
is anticipated to surge to 115% of capacity (707 capacity, 610
current enrollment, 0.2 children/du assumed school-child generation
rate). Addition of 300~ additional units on Hansen Hill Ranch will
aggravate overload.
B. Preposition that additional portables can be utilized (60 students
currently in portables) needs to be addressed.
7.4 Parks
A. Determination if an additional neighborhood park is needed within
western unplanned portions of Primary Planning Area of Western
Extended Planning Area.
7.5 Recreation
A. Need to promote (through site planning design) access to stream
corridors for passive recreational use, while respecting the privacy
of owners of property abutting stream corridors.
B. Need to expand park area to serve new development in Western
Extended Planning Area:
8. FISCAL ANALYSIS
A. Estimate of per capita sales taxes needs to be further analyzed.
B. Determination of whether a Lighting and Landscaping Assessment
District is an option for maintenance of open space areas (turn over
to EBRDP? Maintain through Homeowners' Association?).
C. Direction that location, extent, and density of development not pose
a financial burden on Dublin residents and businesses and not draw
upon and dilute fiscal base of remainder of the City (see Section
2.1.4 (D) of General Plan).
9. LAND USE
A. Need to determine whether the site's development will have an impact
on adjacent Williamson Act contract lands resulting from the
extension of urban services.
B. Direction to prevent premature urbanization of agricultural lands
(see Section 7.5 (A) of General Plan). Side issue - will road
network up Donlan Canyon serve to encourage premature urbanization?
-6-
C. Direction that development of non-contracted lands (Williamson Act)
be based on the findings that: 1) lands are suitable for intended
use; 2) development will have adequate urban services; and
3) conversion of use will not have significant adverse effects on
adjoining, contracted lands (see Section 3.2 (B) of General Plan).
D. Direction that abrupt transitions between single family and higher
density residential ~evelopments be avoided (see Section 2.1.3 (A)
of General Plan).
E. Direction that site plans respect the privacy and scale of nearby
residential development (see Section 2.1.3 (B) of General Plan).
F. Need to co~sider feasibility of vehicular access through Valley
Christian Church site.
G. Need to acknowledge public health and safety values of open space
retention.
H. Acknowledgement of fire hazard potential inherent with development
adjoning/on steep wooded slopes.
I. Consideration of density transfers for sub-area of Western Extended
Planning Area (with dedication of development rights).
10. HOUSING
A. Consideration should be given to having developer cooperate with a
non-profit housing provider to enhance potential for construction of
high-quality, below-market rate housing.
11. TRAFFIC
A. Reserve right-of-way and construct improvements necessary to allow
arterial and collector streets to accommodate projected traffic with
the least friction (see Section 5.1 (D) of General Plan).
B. Reserve right-of-way for Hansen Drive extension to the western hills
(see Section 5.1 (G) of General Plan).
C. Direction to prevent misuse of neighborhood collector streets by
through traffic (see Section 5.1 (I) of General Plan).
D. Need to mitigate impacts to Dublin Bouelvard/San Ramon Road
intersection resulting from additional trips generated from
development in the Western Extended Planning Area.
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E. Need to mitigate impacts to Silvergate Drive re;ulting from
additional trips generated from development in the Western Extended
Planning Area.
-
F. Need for City to formulate traffic policy of volume/capacity ratios
for major street intersections (is Level of Service D or E
acceptable?).
G. Need to identify and examine all feasible physical mitigation
measures to Dublin Boulevard/San Ramon Road intersection to improve
capacity. ,
H. Need to examine possible routes for extension of Dublin Boulevard to
serve western portion of site.
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