HomeMy WebLinkAbout8/1/1988 PC Agenda CITY OF DUBLIN
Development Services Planning,•Zonin g 829-4916
' P.O. Box 2340 �3uilding & Safety 829-0822
Dublin, CA 94568 Engineering/Public Works 829-4927
DECLARATION OF POSTING
•
I declare under penalty of perjury that the foregoing Agenda for the
Dublin PlanningCommission meetingof f� q
(�•u�1 l , 1983 was posted
at the Dublin Library, 7606 Amador Valley Bo> evard, Dublin, California, on
the �Q 1 of - 3 , 198 , _�_ (� 'p.m.
by
Executed this { `— day of , 190�, at Dublin,
(jjAa
California.
Laurence L. Tong
Planning Commission Secretary by
j 0
Planni Secretary
AGENDAomN
CITY OF DUBLIN
PLANNING COMMISSION
Regular Meeting - Dublin Library Monday - 7:00 p.m.
7606 Amador Valley Blvd., Meeting Room August 1, 1988
1. CALL TO ORDER
2. ROLL CALL
3. PLEDGE OF ALLEGIANCE TO THE FLAG
4. ADDITIONS OR REVISIONS TO THE AGENDA
5. MINUTES OF PREVIOUS MEETING - July 18, 1988
6. ORAL COMMUNICATION - At this time, members of the audience are permitted
to address the Planning Commission on any item which is not on the
Planning Commission agenda. Comments should not exceed 5 minutes. If
any person feels that this is insufficient time to address his or her
concern, that person should arrange with the Planning Director to have
his or her particular concern placed on the agenda for a future meeting.
7. WRITTEN COMMUNICATIONS
8. PUBLIC HEARINGS
8.1 PA 87-045 Hansen Ranch General Plan Amendment Study, Planned
Development Prezoning, Tentative Subdivision Map No. 5766,
and Annexation request for 248 dwelling units on 147 acres,
west of Silvergate Drive and north Hansen Drive (continued
from July 18, 1988 meeting)
9. NEW OR UNFINISHED BUSINESS
10. OTHER BUSINESS
11. PLANNING COMMISSIONERS' CONCERNS
12. ADJOURNMENT
(Over for Procedures Summary)
4. r
CITY OF DUBLIN
PLANNING COMMISSION
AGENDA STATEMENT/STAFF REPORT
Meeting Date: August 1, 1988
TO: Planning Commission
FROM: Planning Staff i
SUBJECT: PA 87-045 Hansen Ranch General Plan Amendment
Study, Planned Development Prezoning, Tentative
Subdivision Map No. 5766, and Annexation request
for 248 dwelling units on 147 acres, west of
Silvergate Drive and north Hansen Drive.
GENERAL INFORMATION:
PROJECT: A General Plan Amendment Study, Planned
Development, Prezoning, Tentative Subdivision
Map No. 5766, and Annexation request to allow
248 dwelling units, including 141 single family,
37 patio homes, 36 custom homes and 34
townhomes, on 147 acres in unincorporated
Alameda County, west of Silvergate Drive and
north of Hansen Drive.
APPLICANT/REPRESENTATIVE: Gordon D. Jacoby, Vice President
Venture Corporation
P.O. Box 847
Mill Valley, CA 94942
PROPERTY OWNERS: George K. Hansen, Alicia Hansen,
Eleanor O'Neill & Ruth Reilly
547 Brookfield Drive
Livermore, CA 94550
William H. Gale, Jr., Esq.
62 West Neal
Plesanton, CA 94566
LOCATION: West of Silvergate Drive, north of Hansen Drive,
and south of Rolling Hills Drive
ASSESSOR PARCEL NUMBERS: 941-110-1-9 and 941-110-2
PARCEL SIZE: 147+ acres
GENERAL PLAN
DESIGNATION: Part of the site is within the Primary Planning
Area; part is within the Extended Planning Area.
Two portions of the site are currently
designated single family residential, with
density range to be determined based on site
conditions; one portion of the site is
designated medium density, 8+ dwelling units per
acre. Adjusted unit range is 42 to 109 dwelling
units.
EXISTING ZONING
AND LAND USE: A, Agricultural (Alameda County), vacant
property used for limited cattle grazing.
COPIES TO: Applicant
Owner
8 I Mark Trembley, EIP
ITEM NO. File PA 87-045
SURROUNDING LAND USE
AND ZONING: North: Single family and multi-family, zoned
PD; grazing land, zoned A
South: Single family, zoned R-1; church, zoned
A; grazing land, zoned A
East: Multi-family and single family, zoned PD
West: Grazing land, Zoned A
ZONING HISTORY: February 18, 1956, Alameda County zoned the site
A, Agricultural.
APPLICABLE REGULATIONS:
The Dublin General Plan establishes policies and standards to control land use
and development within this area.
Section 8-31.0 (Planned Development District Intent) states, in part, that
Planned Development Districts are established to encourage the arrangement of
a compatible variety of uses on suitable lands in such a manner that the
resulting development will:
a) Be in accord with the Policies of the General Plan of the City of
Dublin;
b) Provide efficient use of the land that includes preservation of
significant open areas and natural and topographic landscape
features with minimum alteration of natural land forms;
c) Provide an environment that will encourage the use of common open
areas for neighborhood or community activities and other
amenities;
d) Be compatible with and enhance the development of the general
area;
e) Create an attractive, efficient and safe environment.
Section 8-1.2 of Chapter 1, Title 8 (Subdivision Ordinance Intent) states, in
part, that it is the intent of this Chapter to promote the public health,
safety, and general welfare; to assure in the division of land consistency
with the policies of the General Plan and with the intent and provisions of
the Zoning Ordinance; to coordinate lot design, street patterns, rights-of-
way, utilities and public facilities with community and neighborhood plans; to
assure that areas dedicated for public purposes will be properly improved
initially so as not to be a future burden upon the community; to preserve
natural resources and prevent environmental damage; to maintain suitable
standards to insure adequate, safe building sites; and, to prevent hazard to
life and property.
ENVIRONMENTAL REVIEW: The City proposes to adopt an Environmental Impact
Report (EIR) which finds the proposed project may have a significant
impact on the environment.
NOTIFICATION: Public Notice of the July 18, 1988 hearing was published in
The Herald, mailed to adjacent property owners, and posted in public
buildings.
BACKGROUND
This item was continued from the July 18, 1988 Planning Commission Meeting.
It was the consensus of the Commission to consider and provide recommendation
on the General Plan Amendment and Environmental Impact Report. The Planned
Development Prezoning, Tentative Map and Annexation requests would be
considered by the Planning Commission after the City Council has taken action
on the GPA and EIR.
At the July 18, 1988 Planning Commission Meeting, the Commission began
considering discussions and took public testimony on the EIR and the GPA
issues including land use designation, grading, significant vegetation, visual
impacts, preservation of open space and density range. After which the
Commission continued the item and directed Staff to:
-2-
1. Meet with the Applicant to discuss gross density as determined by the
General Plan.
2. Resolve the discrepancy between the LOS indicated for the Dublin
Boulevard/San Ramon Road intersection, as presented in the DEIR and the
Final EIR Addendum.
Staff met with the Applicant on July 20th and July 25th to discuss the
Applicant's proposed density and the Staff recommended density range for the
project.
ANALYSIS
Net vs. Gross Density Range
Page 4 of the Dublin General Plan indicates "Density measurements for General
Plan purposes are based upon gross residential acreage".
The table presented by the Applicant depicting the acreage, unit count and
density range of surrounding developments is incorrect in that the Applicant
included the open space acreage when calculating the density. The figures
prsented by Staff in the July 18, 1988 Staff Report are correct, as land
designated open space was excluded from the calculations.
Dublin Boulevard/San Ramon Road Intersection
At the July 18, 1988 Planning Commission Meeting it was noted that there were
inconsistencies between the Levels of Service for the Dublin Boulevard/San
Ramon Road intersection indicated in Table 3-8 in the DEIR and the Final EIR
Addendum.
TJKM, the City's traffic consultant, has reviewed the two documents,
indicating Table 3-8 in the DEIR is correct (See Attachment 14, TJKM memo).
The LOS for the Dublin Boulevard/San Ramon Road intersection is F for existing
development plus proposed project plus cumulative development. For existing
development and cumulative development, but no-project, the LOS is E.
Staff Recommended Land Use Designation vs. Applicant's Proposal
Staff is recommending three land use designations for the Hansen Hill Ranch
property (See Attachment 6, July 18, 1988 Staff Report).
Open Space -0- units per acre
Medium-Low Density 6.1 to 8 D.U./Acre
Single Family-Low Density .5 to 2.8 D.U./Acre
There are primarily three areas on the Hansen Hill Ranch project in which the
Staff recommendation differs from the Applicant's proposal (see Attachment
15).
Area 1: 30% slope and oak woodland areas, the Applicant proposes grading
roadway and approximately 7 units. This area is in conflict with General Plan
policies restricting development and grading on 30% slopes and requiring
preservation of oak woodland areas.
Area 2: 30% slope and oak and riparian woodland areas significant
ravine/swale area. The Applicant proposes approximately 20 units road and
grading within this area. Development in this area is in conflict with
General Plan policies relating to open space and slopes.
Area 3: 30% slopes, oak woodland and riparian habitat vegetation. The
Applicant proposes approximately 3 single family units and 26 custom lots road
and grading within this area. Development within this areas is in conflict
with General Plan policies relating to open space preservation and 30% slopes.
The Staff recommendation is based upon the application of General Plan
policies to the project site (within the primary planning area and the
extended planning area). These policies include 1) considering residential
-3-
n n
development on the moderate slopes and multi-family densities on flatter
areas, 2) restricting development and preserving as open space ridgelines, oak
woodlands, riparian habitats and slopes of 30% or greater.
The Staff recommendation considers General Plan policies in conjunction with
the location of the constraint areas (oak woodlands, riparian habitats, 30%
slopes and ridgelines) as identified on the various constraint maps contained
in the Environmental Assessment Study (See Attachment 16) and the DEIR, in
particular the mitigated alternative.
The composite constraint map includes two main categories 1) areas unsuitable
for construction and 2) areas of constrained construction.
The Staff recommended land use designations are intended to be general in
nature as is typical of a General Plan. The boundaries of the land use
designations follow the boundaries identified by the constraints of the
General Plan polices.
Examination of the composite constraint map reveals areas which are subject to
interpretation shown as constrained construction rather than as areas
unsuitable for construction. Through use of all the contraint maps (slope
analysis, visual features/sensitivity, hydrology/geology and vegetation),
judgments were made in the Staff recommendation to include certain areas
within the buildable acreage of the site and to exclude certain areas from the
buildable portion of the site (see Attachment 17). Areas involving judgment
calls include areas which contain oak woodlands with slopes less than 30%,
areas which contain slide areas which may be mitigated with engineering and
reconstructing of the slides, slopes 30% or greater, and for northwestern
central knolls.
Area 1 - represents an area with oak woodlands primarily located on slopes of
less than 30%. Staff recommends residential land use designation, however,
the General Plan requires preservation of oak woodlands. Zoning is required
to be consistent with the General Plan. This area will be prohibited from
development and may be eligible for density transfer (density transfer is an
issue addressed in consideration of prezoning).
Area 2 - represents slopes of 30% or greater and oak woodland areas. Staff is
recommending open space land use designation for this portion of the site.
Area 3 - represents a knoll area which the composite constraint map indicated
as unsuitable for construction. Staff is recommending residential designation
of the portion of the knoll which does not involve 30% slopes or oak
woodlands, in that this knoll is not visually prominent from I-580.
Area 4 - represents a knoll area, slopes 30% or greater and oak woodlands.
Staff is recommending residential designation for this portion of the site in
that it provide access for development of an approximate 4-acre area which
otherwise would be landlocked by undevelopable land.
Area 5 - represents the two major knolls and surrounding land on the site.
Staff recommends open space designation of two sites as the area is highly
visable from off-site.
Area 6, 7 and 8 - represent areas of slides indicated on the Environmental
Assessment Study Maps. Staff recommends residential designation on portions
of these areas in that repair of the slides may allow development of the
areas.
As discussed on page 7 of the July 18, 1988 Staff Report, Policy 7.3B allows
for a transfer of density for woodland areas where grading or development
could typically occur had the woodland not been located there. For example,
property designated for residential development (open space is excluded in
that residential development is not permitted) which contains slopes of less
than 30% and which contain oak woodlands could transfer density from that
portion of the oak woodland site to a portion of the site in which oak
woodlands were not located. Implementation of this policy would occur at the
Planning Development Prezoning and Tentative Map stage and does not affect the
land use designations established by the General Plan.
-4-
The Commission should note that the discrepancy in the Applicant's proposed
open space acreage identified in the July 18, 1988 Staff Report was based upon
the Applicant's conflicting acreage presented in his submittal. A second item
which the Commission should note is that Applicant's statement indicating the
designation of areas on the site as open space may constitute a taking of
development rights, is inaccurate in that under the current Alameda County
Agricultural Zoning Designation for the site the project site would be
permitted a maximum of one unit (substantially less than the 248 proposed by
the Applicant). Designation of a portion of the site as open space will not
constitute a taking of development rights as the development rights do not
currently exist on the site.
Three General Plan Amendment items remain undiscussed from the July 18, 1988
Staff Report: 1) Circulation, 2) Deletion of Hansen Drive Extension/Addition
of Alternate Road, 3) Public Facilities/Services.
Circulation:
The General Plan policy issue associated with circulation involves the
addition of a General Plan policy establishing the maximum acceptable LOS for
major intersections within the City (Refer to page 9 of the July 18, 1988
Staff Report for discussion on circulation). The City's General Plan
currently does not include any policies establishing acceptable LOS in the
City. The Planning Commission should indicate whether or not it wishes to
consider such policies.
Deletion of Hansen Drive Extension/Addition of Alternate Road
The General Plan designates Hansen Drive as an extended road west through the
Valley Christian Center. The Hansen Hill Ranch project proposes elimination
of the road extension (see page 10 of July 8, 1988 Staff Report).
The General Plan Amendment includes deletion of the Hansen Drive extension and
the addition of a collector street perpendicular to Dublin Boulevard running
through the Valley Christian Center and addition of a collector street
parallel to Hansen Drive.
Public Facilities/Services
(Refer to Page 10 of the July 18, 1988 Staff Report for discussion of public
facilities/services.)
Although the General Plan includes policies requiring special fire
precautions, the General Plan does not include specific policies requiring
buffer zones.
The safety element of the General Plan would need to be amended to address the
issue of buffer zones between residential development and open space areas.
RECOMMENDATIONS
When Staff met with the Applicant on July 20 and July 25, 1988, the Applicant
indicated he would like an additional opportunity to clarify and discuss the
proposed development with the Planning Commission in a non-decision making
setting.
Staff and the Applicant recommend that the Planning Commission first address
the two key issues of 1) where to develop and 2) how much to develop:
1. Where to Develop: The Planning Commission should recommend what
areas on the site have potential for reasonable and desirable
development. The Planning Commission should give consideration to the
environmental constraints and General Plan goals of the City in
conjunction with the needs of the Applicant.
2. How Much to Develop: The Planning Commission should recommend
what amount and type of development is potentially reasonable and
desirable. The Planning Commission should recommend the General Plan
land use designation and density range, so that the number and type of
dwelling units can be determined.
-5-
To facilitate discussion and clarification of the proposed project and the
Staff Study, Staff and the Applicant suggest a "workshop" format. With a
workshop format, the Planning Commission would keep the public hearing open,
but go to a non-decision making study session, or workshop, format.
This workshop format would allow:
- the Applicant and Staff to clarify and discuss the proposal and the
alternatives with the Planning Commission;
- the Planning Commission to give informal and general direction;
- the Planning Commission to determine the appropriate time for public
comments.
Prior to making any decisions on the proposed project, the Planning Commission
would need to reconvene in its regular meeting format, receive any additional
testimony, pose questions, close the public hearing, deliberate, then take
action.
In addition to the issues of where to develop and how much to develop, the
Planning Commission should address the other issues identified in the Staff
Report and any others raised by the Planning Commission. The additional
issues include:
1. Adequacy and completeness of the Final EIR.
2. Land Use Designation - Staff recommends three General Plan land
use designations for the Hansen Hill Ranch site, as generally
depicted in Attachment 6:
a. Open Space/Stream Corridor
b. Low Density Single-Family Residential (.5 - 2.8 D.U./Acre)
c. Medium Density Residential (6.1 - 8 D.U/Acre)
3. Amend General Plan to incorporate entire Hansen Hill Ranch project
within the primary planning area.
4. Amend General Plan to delete Areas 5, 6 and 7 from Table I and
Figure 4 of the General Plan.
5. Amend General Plan policy and map with regard to Hansen Drive
extension.
6. Amend General Plan to include alternate roadway serving Hansen
Hill Ranch site (Valley Christian Center access road) and
designate as a collector street.
7. Amend General Plan to include policy establishing level of service
D as maximum level of service acceptable.
8. Amend General Plan to include policies requiring fire protection
buffer zone around perimeter of residential development which
interface with open space lands.
After the Planning Commission addresses all of the issues, the Planning
Commission should direct Staff to prepare a resolution incorporating the
Planning Commission's recommendations.
If the Planning Commission needs additional time to address the issues in the
workshop format, Staff would suggest continuing the workshop to Tuesday,
August 16; Wednesday, August 17th, Tuesday, August 23rd; and/or Wednesday,
August 24th.
The Planning Commission may also want to consider an additional field trip to
the site to better understand the proposal and the alternatives. The Planning
Commission should consider scheduling such a field trip.
-6-
FORMAT: 1) Open public hearing and hear Staff presentation.
2) Keep public hearing open, but recess to a non-decision
making workshop format (Study Session)
3) Discuss and clarify issues and give informal and general
direction
4) Continue workshop to specific date, time and place.
Attachments
REFER TO JULY 18, 1988 STAFF REPORT FOR ATTACHMENTS 1 THROUGH 13.
Attachment 1: Summary of Impact and Mitigation
Attachment 2: General Plan Policies
Attachment 3: General Plan Figure 4 Sites for Housing Development
Attachment 4: DEIR Figure 4-1 Mitigated Alternative
Attachment 5: DEIR Table 3-8 Intersection Levels of Service
Attachment 6: Staff Study General Plan Land Use Designation July 1988
Attachment 7: Letter Schenone & Peck 7/5/88
Attachment 8: General Plan Primary Planning Area Map
Attachment 9: General Plan Extended Planning Area
Attachment 10: Hansen Hill Ranch EIR Final Addendum (under separate cover)
Attachment 11: Reduced Copy Tentative Map 5766 9 Sheets (full size under
separate cover)
Attachment 12: Reduced Copy of Preliminary Landscape Plan (full size under
separate cover)
Attachment 13: Reduced Copy of Preliminary Landscape Plan, Townhouses,
Landscape Concepts and Prototypes Planning 5 Sheets
(full size plans under separate cover) .
Attachment 14: TJKM memo dated received July 26, 1988
Attachment 15: Staff Study July 1988 Areas of Difference
Attachment 16: Hansen HIll Ranch Environmental Assessment Study dated
December 1986
Attachment 17: Staff Study July 1988 areas of Judgment Call
Attachment 18: Cut and Fill Map
OTHER ITEMS HELPFUL IN REVIEW OF PROJECT:
Draft EIR
General Plan
-7-
4637 Chabot Drive,Suite 214
Pleasanton Ca. 94566
(415)463-0611
MEMORANDUM
DATE: July 27, 1988 RECEIVED
TO: Maureen O'Halloran, Senior Planner
JUL p
FROM: Chris Kinzel DUBU
SUBJECT: Hansen Hill Ranch Volume-to-Capacity Ratio Calculations N RAN
N�IG
Summary: The volume-to-capacity ratio (V/C) calculations on Table 3-8 are
correct. The mitigation measures attached to your letter dated July 21st are still
applicable for mitigation to Level of Service D.
Explanation: Brian's telephone comments about lost yellow time are an incorrect
explanation for the discrepancy for the difference in V/C calculations between
Table 3-8 and the V/C sheets in the addendum. The correct explanation is as
follows: after the V/C calculation sheets were prepared, but before Table 3-8 was
finalized, construction work at the San Ramon Road/Dublin Boulevard intersection
resulted in additional intersection capacity. This is reflected by V/C ratios on the
table that are lower than those on the V/C calculation sheets.
The mitigation measures are still applicable. You should also be aware that
additional mitigation measures have been developed subsequent to preparation of
the environmental impact report (EIR) that will further improve the future San
Ramon Road/Dublin Boulevard level of service.
One final note: the mitigation measures in the EIR are appropriate for the project
size specified in the EIR. If the density in the Hansen Hills project decreases
during the hearings process, fewer mitigation measures at the San Ramon
Road/Dublin Boulevard intersection may be appropriate.
rhm
157-001
TJKM MEMO
t 4 DATED RECEIVED
. . . a g JULY 26, 1988
PLEASANTON•SACRAMENTO•FRESNO• CONCORD
- 1. Summary
I
IResource Impact Mitigation
Schools Net capital fiscal impact to Compliance with Amador
the Amador Valley Joint Valley District's impact fee.
I Union High School District
of a positive S953,000 upon
compliance with District's
Iimpact fee.
No net capital fiscal im- Institute a Development
Il pacts to Murray (element- Impact Fee as authorized
ary) School District from under recent legislation
proposed project. Net capi- (AB 2926).
tal fiscal impacts from
I cumulative development
would be negative.
I Traffic Potential for decrease in Widen eastbound approach
the Level of Service at of the intersection to have
Dublin Boulevard/San Ra- two right-turn lanes, one
mon Road from Level of left-turn only lane, one
a Service (LOS) D to LOS F shared through and left, and
when combining project one through only lane.
effects with the cumulative
impacts of other projects. Widen westbound approach
to have three left-turn
al
lanes.
IICumulative increase in daily 1. Reduce project size or
traffic on Sivergate Drive 2. Encourage the use of
between Peppertree Road Dublin Boulevard by
i and Creekside Drive beyond a. Choosing Alterna-
the environmental capacity. tive 1 as second
access road
I b. designing access
road as major col-
lector with few
11 intersecting drive-
ways
c. make access road
as direct as possi-
ble to Dublin
1,11
Boulevard.
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City Of Dublin, California EIP Associates
ATTACHMENT Ib -
. _. ,
..._,.
DRAFT
ENVIRONMENTAL ASSESSMENT STUDY
FOR THE
HANSEN HILL RANCH
C
by
EIP Associates
319 Eleventh Street
San Francisco, CA 94103
for
The City of Dublin
December 1986
TABLE OF CONTENTS
HANSEN HILL RANCH SITE ASSESSMENT REPORT
Page
1. INTRODUCTION 1-1
1.1 Purpose and Objectives of the Site Assessment Study 1-1
1.2 Description and Location of Study Area 1-1
1.3 Site Assessment Procedure 1-2
2. GEOTECHNICAL STUDIES 2-1
2.1 Site Geology: j Obecti:�es and Methods 2-1
2.1.1 Existing Conditions 2-1
2.1.2 Policy Review 2-1
2.1.3 Development Constraints and Opportunities (Constraints Rating) 2-2
2.1.4 Data Sources 2-3
2.2 Soils: Objectives and Methods 2-4
2.2.1 Existing Conditions 2-4
2.2.2 Policy Review 2-4
2.2.3 Development Constraints and Opportunities (Constraints Rating) 2-4
2.2.4 Data Sources 2-5
2.3 Hydrology: Objectives and Methods 2-5
2.3.1 Existing Conditions 2-5
2.3.2 Policy Review 2-5
2.3.3 Development Constraints and Opportunities (Constraints Rating) 2-6
2.3.4 Data Sources 2-7
3. VEGETATION AND WILDLIFE 3-1
3.1 Vegetation: Objectives and Methods 3-1
3.1.1 Existing Conditions 3-1
3.1.2 Policy Review 3-3
3.1.3 Development Constraints and Opportunities (Constraints Rating) 3-6
3.1.4 Data Sources 3-10
3.2 Wildlife: Objectives and Methods 3-7
3.2.1 Existing Conditions 3-8
3.2.2 Policy Review 3-9
3.2.3 Development Constraints and Opportunities (Constraints Rating) 3-9
3.2.4 Data Sources 3-10
4. VISUAL QUALITY 4-1
4.1 Objectives and Methods 4-1
4.2 Existing Conditions 4-4
4.3 Policy Review 4-4
4.4 Development Opportunities and Constraints 4-8
4.5 Data Sources 4-9
5. SLOPE ANALYSIS 5-1
5.1 Objectives and Methods 5-1
5.2 Existing Conditions 5-2
86123
( TABLE OF CONTENTS continued
5.3 Slope Analysis and Visual Quality
5-3
5.4 Policy Review
5-3
5.5 Development Opportunities and Constraints 5-4
5.6 Data Sources 5-6
6. NOISE 6-1
6.1 Objectives and Methods 6-1
6.2 Existing Conditions 6-2
6.3 Policy Review 6-2
E.4 O pertunities and Constraints(Constraints-Rating) 6-2
6.5 Data Sources 6-2
7. ARCHAEOLOGICAL RESOURCES 4-1
8. PUBLIC SERVICES 8-1
8.1 Objectives and Methods 8-1
8.2 Existing Capacity and Proximity 8-2
- Fire Protection 8-2
- Police
8-3
- Schools
8-3
- Solid Waste 8-4
- Parks
8-4
8.3 Development Opportunities and Constraints(Constraints Rating) 8-4
8.4 Data Sources 8-5
9. FISCAL ANALYSIS 9-1
9.1 Objectives and Methods 9-1
9.2 Cost Estimates for City Services 9-1
9.3 Revenue Thresholds 9-2
9.4 Possible Transfer of Open Space to EBRPS 9-4
9.5 Review of LAFCO Requirements 9-6
9.6 Opportunities and Constraints 9-6
9.7 Data Sources 9-7
10. LAND USE 10-1
10.1 Objectives and Methods 10-1
10.2 Site History
10.3 Current Applicable Ordinances, Policies in the Primary 10-2
and Extended Planning Areas
10.4 Impacts of a Potential Road System 10-11
10.5 Policy Review 10-13
- Residential Compatibility 10-13
- Public Health and Safety 10-14
- Agricultural 10-15
- Recreation 10-15
86123 ii
s TABLE OF CONTENTS continued
- Scenic Highways 10-16
- City and Regional Housing Goals 10-16
10.6 Development Opportunities and Constraints (Constraints Rating) 10-18
10.7 Data Sources 10-19
11. CONCLUSIONS 11-1
11.1 Composite Constraints Summary 11-1
11.2 Analysis of Preliminary Site Concepts 11-2
11.-1- for De':elcpment 11-3
12. REPORT PREPARERS 12-1
86123 iii '
•
1 INTRODUCTION
1.1 PURPOSE AND OBJECTIVES OF THE SITE ASSESSMENT
The Hansen Hill Development Corporation seeks the City of Dublin's approval for
residential development on the Hansen Hill Ranch site. This property of approximately
147 acres,is on the western boundary of the City and is wholly within Alameda County.
In response to the applicant's request for a General Plan Amendment study, the City
Council has authorized the Planning Department and EIP Associates to proceed with a
two-phase study program with respect to the Hansen property. The first phase, as
expressed in this report, is a site inventory and assessment of the area, involving such
environmental and planning factors as geotechnical conditions, vegetation and wildlife,
visual quality, slope, public services and land use, and current agency policies and
regulations. This phase will establish the background conditions and the analysis of the
constraints and opportunities bearing on potential site development. Moreover, this
report will serve as a general guide for subsequent site planning and design work and will
establish baseline conditions for any required environmental impact report on a proposed
project for the property.
The Site Assessment will provide some insight into the second phase of the program, or
the General Plan Amendment Study. A review of relevant City General Plan policies at
this initial phase, against the background of a detailed site analysis, will facilitate
recommendations regarding possible revision of these polcies as a part of the General Plan
Amendment Study.
1.2 DESCRIPTION AND LOCATION OF THE STUDY AREA
The Hansen Hill site in the gently rolling foothills adjacent to the City of Dublin's western
boundary, is characterized by a series of parallel swales and knolls covered with
86123 1-1
•
1.Introduction
grasslands and oak woodland. Flatter sections of the knolls offer views over the valley
below and a open space quality that the applicant desires to incorporate into the
residential development of the site.
The site is located less than three miles from the intersection of Interstates 580 and 680
as shown in the following Site Location Map. The 147-acre property has local access from
Hansen Drive, Silvergate Drive, and Martin Canyon Drive,just off of Rolling Hills Drive.
Adjacent land uses include the Hatfield and Kaufman and Broad residential developments
to the north, existing single-family residences on Silverage and Hansen Drive, and vacant
properties of the Nielsen and Cronen families to the north and west. The Valley Christian
Center is located on the south boundary of the property.
1.3 SITE ASSESSMENT PROCEDURE
The primary objectives of the assessment procedure are to (1) provide detailed
information to the Hansen Hill Development Corporation on the environmental
characteristics of the site, (2)to provide information to the City of Dublin staff for use in
reviewing a site development plan prepared by the applicant, and (3) to provide the
envirdrjnntal setting basis for the General Plan Amendment and the EIR for the
development plan.
Development of the Hansen Hill Ranch will be dependent upon the environmental
constraints and suitabilities of the site's natural features to accept construction. The
environmental and planning factors used in assessing constraints and suitabilities to site
development and construction include:
o Geology,Soils and Hydrology
o Vegetation and Wildlife
o Visual Quality
o Slope Analysis
o Noise
o Archaeological and Historical Resources
o Public Services
o Fiscal Analysis
o Land Use
Environmental data are portrayed on individual factor maps contained in the plastic
envelopes of this report. The data are assigned constraint ratings reflecting degree of
86123 1-2
SITE LOCATION MAP FIGURE 1-1
r
\ . -4',.. 1;Z§:'. .‘ 4/:' ••
SAN RAFAEL '
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kN 7i. :.„ • OAKLAND PROJECT SITE
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.'t
e. .� '7 Sw.•.. f+t iE
't"''" + SAN MATED ‘iitiv,"17.-
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~ � '. ..... .. :1 • SAN JOSE,._ A
' SOURCE EIP ASSOCIATES
\ A
4 MIKES
iimine\71.4' SAN RAMON so 0-
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•
\/-7S• DUBLIN
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\ PROJECT SITE
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I 30.VERGATE •• i ` Sao
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PLEASANTON ��S,pFE's °~
SOURCE DUEUN GENERAL PLAN _ • 011
p
0_
FEET
s
0 1000 2000 4000
1. Introduction
sensitivity to alteration due to the building of structures, roadways, parking areas and
associated earth grading. The overall objective is to minimize the potential for adverse
environmental impacts during project construction and operation.
For this assessment, constraint ratings as defined in each section of the report are
expressed as a range from "None" to "No-Build." Each rating category is defined as
follows:
None Constitutes no identified constraint to construction or alteration of
existing environmental conditions.
Low Minor constraint to construction or long- or short-term alterations of
existing conditions.
Moderate Constitutes moderate constraint to construction or apparent long- or
short-term alteration of existing environmental conditions.
High Constitutes high constraint to construction or apparent long- or
short-term alteration of existing environmental conditions.
No Build Areas that are not suitable for construction; best left in existing
condition, or may be used for open space buffer opportunities.
In the conclusion (Chapter 12) section of this report, a Summary Composite Constraints
Map is provided summarizing the constraint data presented in each chapter. The
Composite Constraints Map shows the aggregation of all high constraints ratings, labeled
"Construction Constrained," while all of the no-build ratings are assembled under
"Construction Unsuitable." The first category shows where overlapping constraints occur
and where resulting impact mitigation techniques for locating structures and other
features would be more difficult. The Composite Constraints Map together with the
individual factor maps, contributes to Phase II work elements of site planning and design
by showing areas most suitable for development, areas best suited for open space and
areas suitable for varying degrees of land development.
86123 1-4
2 GEOTECHNICAL STUDIES
2.1 SITE GEOLOGY:OBJECTIVES AND METHODS
2.1.1 EXISTING CONDITIONS
The project site is located within a geologically complex area, where extensive faulting
and folding of the geologic material has occurred in the past. This condition is typical of
many areas within the Coast Ranges of northern California. The Dublin area geology has
been mapped by a number of geologists in the past, including Wagner,1 Dibblee,2 and
Nielsen.3 Information from these authors form the basis for the discussion below.
The site is located in the Central Coast Range Mountains of California. The rocks
underlying the site are sedimentary in nature, and were deposited in a non-marine
environment in Miocene time(10 to 25 million years ago). The rocks are characterized as
consisting of pebble conglomerates, sandstones, and greenish to greenish-grey mudstone,
with locally thin marl beds. These rocks have been assigned to the Briones Formation,
part of the San Pablo Group. About two million years ago, during the Mt. Diablan
mountain building period, the sediments of the Briones Formation underwent structural
deformation in the form of faulting and folding. The site is located along the southern
limb of a north-northwest/south-southeast trending syncline; the axis of the syncline
corresponds to the channel of the Martin Canyon Creek, along the northern boundary of
the site. The beds of the Briones Formation is reportedly dipping steeply to the northeast.
Since the mountain building event associated with the Mt. Diablo uplift, the site has been
subject to erosion. The erosion has resulted in the rounded hill tops and the steep gullying
on the north-facing slope of the site. In addition, landsliding has taken place on about
one-third of the site. Landslides on the site were mapped by Nielsen, in 1973, from aerial
photography. Topographical features that indicated landsliding also were mapped by
Nielsen. The activity of the slide features was not determined. The Geology Map shows
•
86123 2-1
2.Geotechnical Studies
the slides mapped on the site by Nielsen. The Geology Map also shows those slides and
soil slippage areas that were observed during field reconnaissance for the preparation of
this report. As can be seen from the map, about one-third of the site has been subject to
sliding in the past, and parts of the site are currently experiencing downslope movement.
Most of the slide activity is associated with the steep gullies located on the site and the
oversteepened slopes.
No active faults have been mapped on the project site by Dibblee or Wagner. The active
Calaveras Fault has been mapped more than 1,000 feet east of the site. The site is not
within an Alquist-Priolo Study Zone. Extensive fault investigations occurred on the
adjacent Bordeaux Estates prior to site development by Engeo, Inc. to identify active or
potentially active traces of the Calaveras Fault,but none were identified.4
2.1.2 POLICY REVIEW
The Dublin General Plan identifies all but the eastern 5% of the site as an area requiring
detailed geologic investigations prior to development due to the potential for landslide
hazards. The zone of investigation is shown on the following map.
The site is not located within an Alquist-Priolo Special Study Zone, and the requirements
for fault investigations are therefore not applicable.
2.1.3 DEVELOPMENT CONSTRAINTS AND OPPORTUNITIES
The major development constraint from a geologic point of view is the wide spread slope
instability on the site. About one-third of the site has been identified as containing
landslides, but the slides are not concentrated in a single area;they are spread over about
95% of the site. Some of these slides are currently active, while the activity of other
slides is unknown. However, grading activities, landscaping, and other such changes of
existing conditions could result in renewed sliding activity.
Two approaches can be used for development of a site with the known landsliding
constraints; either avoidance of the slide areas, or repair of the slides as part of the
project grading scheme. For the smaller, currently active slides observed during the field
reconnaissance, which are not part of larger slide masses,repair may be the most feasible
86123 2-2
2. Geotechnical Studies
spy method of addressing the slope instability problem. For the larger slide masses shown
throughout the site, avoidance may be the most effective remedial action. An alternative
approach would be to determine whether the slide masses mapped by Nielsen are deep
slides, shallow slides, active slides, in-active slides, or some other topographic features
unrelated to slides. After the type, depth and activity of each slide mass is identified by
on-site engineering analysis, a decision can be made whether the slides need to be
reconstructed, avoided or if no action is necessary. If the large slide masses are active
and cannot be reconstructed, the areas downslope from the slide, as well as the area on
the slide, would be unsafe for housing. The necessary slide studies should be commenced
as soon as possible and the subsequent information incorporated in the development plan.
Constraints Rating
Feature Rating
Landslides
Large Slides No build or further study on each slide mass being
considered for development
Small Slides Moderate
Soil Slippage Moderate
Landslide Hazard
Area Moderate
2.1.3 DATA SOURCES
(1) Wagner, Jesse Ross, Late Cenozoic History of the Coast Ranges East of San
Francisco Bay, Ph.D.Thesis U.C.B., 1978.
(2) Dibblee, T.W., Preliminary Geologic Map of the Dublin Quadrangle, Alameda and
Contra Costa Counties, California. U.S. Geologic Survey Open File Report 80-537,
1980.
(3) Nielsen, Tor H., Preliminary Photo-Interpretation Map of Landslide and Other
Surficial Deposits of the Dublin 7-1/2 min. Quadrangle, Alameda and Contra Costa
Counties, California; U.S. Geologic Survey Open File Map 75-277-15, 1975.
(4) Engeo, Inc., Report to Harold and Robert Nelson on Geologic Exploration of Nelson
Ranch,Dublin, CA. Job # NT-0756-B6, 1981.
86123 2-3
2. Geotechnical Studies
2.2 SOILS: OBJECTIVES AND METHODS
2.2.1 EXISTING CONDITIONS
The Soil Conservation Service has mapped the site as being underlain by Diablo Clay. The
Diablo Clays are found on rolling to very steep mountainous relief.' The parent material
of the soils is soft interbedded shale and fine-grained sandstone subject to local landslips.
The soils are characterized by having the capability of high post-construction settlement,
and high deformability. All Diablo Clays have a high shrink-swell potential.
Soils on the site have been classified for their agricultural capability by the U.S. Soil
Conservation Service. The eastern portion of the site consists of Diablo Clay on 7% to
15% slope. These soils are rated as Capability Class IIIe-3. This Capability Class
indicates that dry-farmed grains and grain-hay are well-suited for cultivation on Diablo
Clays on 7% to 15% slopes. The remaining portion of the site is underlain by Diablo Clays
on 15% to 30% slopes and Diablo Clays on 30% to 45% slopes, with a capability rating of
IVe-5. This Capability Class rating indicates that the soils are best suited for dry-farmed
grain, grain hay, and grazing.
2.2.2 POLICY REVIEW
The project site is underlain by soils that would not be classified as prime agricultural
land. There are no institutional constraints associated with development and construction
of sites underlain by these soils.
2.2.3 DEVELOPMENT CONSTRAINTS AND OPPORTUNITIES
The main soils constraint on the site relates to the presence of clays with high shrink-
swell potential. This would affect structures and other improvements placed on the site;
soils with shrink-swell potential can damage foundations, roadways, and utilities by
cracking and heaving. The soils would need to be either amended or removed to avoid
future structural damage.
Constraints Rating
Feature Rating
Shrink-Swell Moderate
86123 2-4
^ 2.Geotechnical Studies
2.2.4 DATA SOURCES
(1) U.S. Department of Agriculture, Soil Conservation Service, Soil Survey,
Alameda County, California, 1966.
2.3 HYDROLOGY:OBJECTIVES AND METHODS
2.3.1 EXISTING CONDITIONS
The project site is located with;„ the Martin Canyon Creek watershed. Martin Canyon
Creek is a tributary to South San Ramon Creek,flowing north-south east of Dublin. In the
lower reaches of Martin Canyon Creek, on the west side of Highway 680, water backs up
behind the freeway during 100-year storm events, as mapped by the Federal Emergency
Management Agency.1 No flooding has been identified to occur on the project site as a
result of 100-year storm events.
The Martin Canyon Creek is located along the northern project site boundary. The creek
meanders along the site boundary along a deeply incised channel and extensively eroded
creek banks. The slope of the creek is approximately 90 feet in 4800 feet or about 2%.
The creek receives runoff from the project site, where flows are concentrated in gullies,
acting as small tributaries to the creek. The gullies are also deeply incised and the banks
are sparsely vegetated; as a result, runoff moves at high velocities down toward Martin
Creek channel, contributing to the channel erosion.
At the eastern site boundary, the channel flows are conveyed through a six-by seven-foot
box culvert under Silvergate Drive. The box culvert was installed last year and designed
to accommodate the 15-year design storm; the culvert was designed assuming full
development of the watershed.
2.3.2 POLICY REVIEW
The Martin Canyon Creek is not within the jurisdiction of the Alameda County Flood
Control District. However, the District would make recommendations regarding
improvements along the channel. The County standards require that a channel must be
able to contain the 15-year design storm plus a one foot freeboard or the 100-year storm.
The District also requires access to the channel for maintenance purposes.
86123 2-5
•
2.Geotechnical Studies
Usually access to a channel is provided by a road built in an easement along each side of
the channel. If the channel banks have a slope less than 2:1, the width of the access
easement should be 20 feet from the top of the bank. If the channel banks are steeper
than 2:1, an additional width of easement must be provided equivalent to the width that
would be occupied by a 2:1 slope. For example, a 12-foot high channel bank,steeper than
2:1 would need a setback of 24 feet (equivalent to a 2:1 slope 12 feet high) plus the
standard 20 foot access easement for a total of 44 feet. The slope setback would be
measured horizontally from the base of the channel slope. Because the slopes along
Martin Canyon Creek in most places are steeper than 2:1, and have a height in excess of
10 feet in certain places, the channel setback would be on the order of 40 to 50 feet from
the toe of the channel. An alternative to continuous channel access would be to provide
discrete access points at regular intervals along the creek. This would not mean that
setbacks from the channel should not be provided. Because the creek is currently eroding,
it would be prudent to allow for at least a 20-foot creek setback for improvements. This
setback also would apply to the tributary gullies.
In addition to creek setbacks, the Alameda County Flood Control District would be
recommending creek bank stabilization at channel stress points. Stabilization could be
accomplished by rip-rapping at strategic points along the channel.
In order to minimize erosion, flow velocities in the creek would need to be kept low; this
would mean ensuring that flow velocities remain below 6 feet per second. Decreasing the
flow velocity can be accomplished by installation of drop structures along the channel and
within the watershed.
2.3.3 DEVELOPMENT CONSTRAINTS AND OPPORTUNITIES
The hydrological constraints on the site evolve around the ramifications of development
placed adjacent to a creek with existing erosional problems. To prevent damage to
structures from creek erosion, the structures must be placed away from the eroding
channels, and the existing channel stress points must be stabilized. In addition, causes of
erosion must be reduced to a reduced to a minimum. The major erosive force is high flow
velocity, therefore, flow velocities must be reduced. Because residential developments
generally result in higher runoff velocities, due to paved surfaces, the suggested measures
to reduce flow velocities should be incorporated in the project design.
86123 2-6
2. Geotechnical Studies
Constraints Rating
Feature Rating
Creek Erosion No build
2.3.4 DATA SOURCES
(1) Mr. Vince Wong, Alameda County Flood Control District, personal communication,
November 19, 1986.
(2) Mr. Lee Thompson, City of Dublin Department of Public Works, personal
communication, November 16, 1986.
86123 2-7
3 VEGETATION AND WILDLIFE
3.1 VEGETATION: OBJECTIVES AND METHODS
The objectives of this section are to describe the existing vegetative resources on the
project site, summarize those City policies which apply to the vegetation resources in the
Dublin area, and identify development constraints and opportunities on the site. The data
for this section was developed in consultation with representatives of the Dublin Planning
Department, the California Department of Fish and Game and a review of the vegetation
inventory submitted to the City by David Gates and Associates, Landscape Architects.
An on-site field survey was conducted on November 10, 1986 during which the entire site
was walked in a random pattern. All plant species encountered during the field survey
were identified with the aid of various standard field manuals (see Section 3.1.4, Data
Sources).
3.1.1 EXISTING CONDITIONS
•
The predominant plant communities occurring on the site are: annual or non-native
grasslands on the ridge tops, upper slopes and flat areas, chaparral brush areas in some
localities next to the forested areas and a coast live oak/California bay forest mix on the
lower,steeper slopes and canyon bottoms as shown on the following Vegetation Map.
The annual grasslands on the site are composed of non-native grass and forb species
including fescue (Festuca sue), brome (Bromus sue.) and wild oat (Avena sue) grasses. The
livestock grazing favors these annual grasses over the native perennial species. There are
some small areas of native bunchgrasses located at the head of the tributary drainages
(see enclosed Vegetation Map). These remnant stands of bunchgrasses occur in areas
where the grazing pressure is reduced due to the steepness of the slopes. Native
bunchgrass communities are considered a rare native plant community in California. This
once extensive native community has been limited in its extent primarily due to cattle
86123 3-1
.ti
3.Vegetation& Wildlife
r�.
grazing and conversion to non-native annual grasslands. Although rare plant communities
do not have legal standing as do some rare plant and animal species, they are being
recognized as vanishing elements of our natural resource heritage. The stands on-site are
rather small, making their preservation as isolated communities rather useless. A better
and more effective way of preserving the wildlife habitat values of these areas would be
as part of a larger natural open space area extending down the slope. In other areas of
the grasslands, the grazing pressure has been so heavy that invasive weedy species (i.e.,
star thistle(Centaurea 12z)have become established. These heavily grazed areas are most
common along the ridgelines,upper slopes and flat areas in the canyon bottom.
The chaparral community is limited to spot locations along the edges of the forested
areas. These brush stands occur in areas where past disturbances and/or soil
characteristics favor the brushy species. A common species in these brushy areas is the
chaparral broom(Baccharis pilularis),a species which is commonly associated with erosion
sites,burned areas and/or areas of shallow soils.
The coast live oak/California bay forest areas are typified by dense to open stands of
evergreen trees. The coast live oak (Quercus agrifolia) and California bay (Umbellularia
californica) are the dominate trees in these areas. Other tree species also occur within
these forests including the valley oak (Quercus lobata), bigleaf maple (Acer
macropteyllom), California sycamore (Platanus racemosa) primarily along the drainage
courses and creek, and California buckeye (Aesculus californica) on the margins of the
forests where more direct sunlight is available. An understory of poison oak
(Toxicodendron diversiloba)is very limited in extent due to the dense tree canopy and lack
of sunlight and cattle grazing and trampling.
Martin Canyon Creek runs along the northern boundary of the site. Four tributary swales
run down the slopes of the site into Martin Canyon Creek. Vegetation along and
immediately adjacent to these waterways are considered as riparian communities, a
native community commonly associated with intermittent or permanent streams. The
bigleaf maple and California sycamore are indicator species for this community. The
riparian community on the Hansen Ranch site is poorly defined by indicator species. In
some areas of Martin Canyon Creek and along most of the tributary swales the creekside
vegetation is dominated by bays and oaks without any riparian indicator species. The best
86123 3-2
3.Vegetation& Wildlife
defined riparian communities on-site occur along Martin Canyon Creek and along the third
tributary swale from the east end of the site.
A list of rare, endangered or threatened plant species that are known to occur in the
project region and for which suitable habitat occurs on-site is provided in Table 3-1. Of
those sensitive plants listed, the appropriate habitat for three occurs on-site; Santa Cruz
tarweed, Mt. Diablo buckwheat and Diablo rock rose. None of these nor any other rare
plant species was located on-site during the field survey. It is highly unlikely that two of
these three rare plants (specifically the Diablo rock rose and Santa Cruz tarweed) occur
on the site. The Diablo rock rose and Santa Cruz tarweed favor grassland habitats which
for the most part are heavily grazed on this site. Although the site survey was conducted
at the tail end of the blooming season for the Santa Cruz tarweed, if a significant colony
were to survive on-site it is likely that a few plants would have been in bloom and
identifiable. This plant is known to occur in the Pinole area, and was last seen in the hills
east of San Lorenzo in 1915. The Diablo rock rose is known to occur in the Pine Canyon
area of Mt. Diablo approximately 10 miles north of this site. Although the field survey
was conducted after this plant had bloomed,nothing resembling the vegetative features of
this plant was observed on-site.
The Mt. Diablo buckwheat blooms from April-June. Consequently the field survey was
conducted when positive identification of this plant was not possible. It was last sighted
in the Alamo Creek area approximately five miles northeast of the site in 1933. Its
habitat, edge of chaparral, is limited in extent on the site, and the site is just below the
elevational range of this species. The presence of the Mt. Diablo buckwheat is therefore
unlikely,however, it cannot be ruled out without a springtime survey.
3.1.2 POLICY REVIEW
The principal City policies dealing with vegetation resources are contained within the
Conservation and Open Space Elements of the General Plan. The general guiding policy
statement of the City Open Space Element is as follows: "Preserve oak woodlands,
riparian vegetation and natural creeks as open space for their natural resource value"
(Chapter 3.1a.). The General Plan then goes on to identify"riparian vegetation" and "oak
woodlands" as specific resources addressed in the Conservation Element. The policy
statement in regards to riparian vegetation is as follows: "Require open stream corridors
86123 3-3
3.Vegetation& Wildlife
TABLE 3-1
RARE,ENDANGERED OR THREATENED PLANT SPECIES
KNOWN TO OCCUR IN THE PROJECT REGION
Common Name
(Scientific Name) Status1 Potential for Occurrence On-Site2
Mt.Diablo Manzanita /C"e ir.; Suitable habitat chaparral on dry
(Archtostaphylos auriculata) ""ori'R
slopes of sandstone at 500-2,000
foot elevations. Sandstone chapar-
ral does not occur on-site.
Santa Cruz Tarweed E/C1/List 1B This annual herb typically occurs as
(Holocarpha macradenia) colonies in heavy clay soils on gras-
sy flats. Limited habitat occurs in
grassy flats next to Martin Canyon
Creek. Colonies of this rare plant
were not located on the site.
Mt.Diablo Jewel Flower /C2/List 1B This rare annual occurs on talus or
(Streptanthus hispidus) rocky outcrops at 2,000-4,000 foot
elevations. Appropriate habitat
does not occur on-site, and the site
is below the elevational range of the
plant.
Mt.Diablo Buckwheat
/C2/List 1B This annual occurs on the edge of
(Eriogonum truncatum) chaparral on dry slopes between
1,000-1,500 foot elevations. The site
is below the plant's elevation range.
However, its habitat does occur on-
site to a limited extent.
Diablo Rock Rose /C2/List 1B This perennial herb occurs on grassy
(Helianthella castanea) hillsides at 500-4,000 foot elevations
in the San Francisco Bay region.
Habitat does occur on-site, but no
vegetative features of the plant
were observed on-site.
1State/Federal/California Native Plant Society designations as follows:
State Rare(R),Threatened(T),Endangered(E): California Endangered Species Act of
1971.
Federal Endangered (E), Threatened (T), Candidate(C1-Taxa for which the U.S. Fish
& Wildlife Service has information to support listing; C2-Taxa for which the Service
86123 3-4
3.Vegetation do Wildlife
•
TABLE 3-1 continued
requires further study before listing; C3c-Taxa which was previously considered for
candidacy but now excluded because it is too widespread or not threatened at this
time): Federal Endangered Species Act of 1973.
California Native Plant Society, Inventory of Rare and Endangered Vascular Plants of
California, 1984:
List 18-Plants rare and endangered in California and elsewhere.
List 3-Plants about which more information is needed.
List 4-Plants of limited distribution(a watch list).
2Habitat and elevational data source is Munz and Keck, 1968.
of adequate width to protect all riparian vegetation, improve access, and prevent
flooding" (Chapter 7.1). An "adequate width" is open for interpretation and may vary
from site to site. Since the riparian vegetation is poorly defined on the Hansen Hill
Ranch site it is best to refer to a minimum width requirement along Martin Canyon Creek
and the third tributary swale from the east. To adequately preserve the"natural resource
value"of these waterways, a natural corridor of a minimum of 30 feet from the top of the
creek bank should be preserved. Structures, paved roads or any other development
feature should not be allowed within this natural corridor. Unpaved trails may be allowed
to control access through this area and to allow its use as a visual and recreational
resource. The corridor may have to be wider in some areas to "prevent flooding" and/or
"protect riparian vegetation" where it is easily identifiable. Roadways other than access
crossings and structures would only be allowed outside of this natural corridor.
Development designs that would help preserve the integrity of the riparian zone would be
as follows:
o Structures should be separated from the natural corridor by a roadway and they
should face rather than back up to the natural corridor. This prevents dumping of
trash by residents into the corridor, ("out-of-sight-out-of-mind"), and promotes
cleanup of any such dumping.
o Multi-story glass structures should not be allowed to face the corridor. Birds
utilizing the wooded areas are likely to become confused by the reflections in the
glass resulting in collisions.
o Landscape materials should be of natural varieties and should preserve the wooded
character of the area as much as possible. Invasive species such as pampas grass
should not be allowed.
86123 3-5
•
3.Vegetation& Wildlife
/ r
o Fill and cut slopes should not be allowed within the natural corridor and certainly not
beneath the tree canopy of any oak tree in the corridor.
o Landscape lawns and irrigation systems should not be allowed beneath any oak tree
that is to be preserved without some protective measures to prevent root rot and
eventual loss of the tree.
o Any alternations within the creek or drainage swale for either development access or
flood control purposes should minimize disturbance of existing vegetation and avoid
as many trees as possible.
The General Plan policy in regards to oak woodlands states that oak woodlands should be
preserved; however, individual oak trees may be removed on a case by case basis. The
General Plan also directs the Planning Department to develop a heritage tree ordinance to
aid in the decision on which trees may or may not be removed. To date the City has not
developed a "heritage tree ordinance." The direction is clear, however, the removal of
stands of the oak woodlands on-site should not be allowed, and the largest mature trees
should be preserved to the maximum extent possible.
In addition to the City's policies there are various state policies and requirements that
will have to be met before the project site may be developed. The California Department
of Fish and Game (DEG) under Section 1603 of the Fish and Game Code of Regulations
requires a Stream Alteration Agreement be secured before any proposed alteration of
natural waterways may occur. This agreement would cover any proposed modifications to
the creek within its banks including roadway crossings,flood control improvements, etc.
3.1.3 DEVELOPMENT CONSTRAINTS AND OPPORTUNITIES
The development constraints on the site are indicated on the Vegetation Map. The
riparian corridor is the area that no development would be allowed except for access
crossings and limited flood control improvements if necessary. Development within the
coast live oak/California bay forest would be limited to those areas where a minimum of
trees would be removed. Areas with existing openings in the tree canopy and where
housing units may be placed without requiring the removal of numbers of mature trees
should be favored. The native bunchgrass areas should be preserved in a contiguous
natural open space area with the forested areas and the riparian corridor. Other grassland
and chaparral areas have no development constraints in relation to their vegetation
resources. The following table summarizes the development constraints and opportunities
in relation to vegetation resources on the site.
86123 3-6
3.Vegetation& Wildlife
Resource Constraint Rating
Riparian Corridor No Build
Coast Live Oak/California Bay Forest High
Native Bunchgrass stands High
Annual Grasslands and Chaparral Low-No Constraint
3.1.4 DATA SOURCES
Prior to conducting the field work, a literature review was conducted to gather and
evaluate information on the rare plant species and sensitive habitat types with known
occurrences in the region. The basic working list for the rare plant survey was the list of
all rare and endangered plants of California with occurrences in the project vicinity
(California Natural Diversity Data Base 1985). To develop a list of rare plant species
potentially occurring on the site, the working list was refined using geographic
distribution and habitat information provided in standard floristic manuals (Munz and
Keck (1968), McMinn and Maino (1937), Cheatham and Haller (1975)), location data
printouts from the California Natural Diversity Data Base (CNDDB) and unpublished rare
plant status reports prepared for the CNPS(various authors).
3.2 WILDLIFE: OBJECTIVES AND METHODS
The objectives of this section are to describe the existing wildlife resources on the project
site, summarize those City policies which apply to wildlife resources in the Dublin area
and identify development constraints and opportunities on the site. The data for this
section was developed in consultation with representatives of the Dublin Planning
Department, the California Department of Fish and Game and included a review of the
data submitted to the City by David Gates and Associates, Landscape Architects. An on-
site field survey was conducted on November 10, 1986 during which the entire site was
walked in a random pattern. All animal species encountered during the field survey were
identified with the aid of binoculars (7 x 35) and various standard field manuals (see
Section 3.2.4 Data Sources).
•
86123 3-7
3.Vegetation do Wildlife
3.2.1 EXISTING CONDITIONS
Wildlife observed and expected to occur on.the site is typical of the vegetation
communities and habitats the site supports. The grasslands provide nesting, denning and
feeding habitat for small mammals and birds. Larger mammals and birds of prey utilize
these areas as hunting grounds feeding on the smaller mammals, birds and reptiles.
Common species in grasslands would include the following: meadow mice, jackrabbits,*
meadow larks, black shouldered kite,* red-tailed hawk,* turkey vultures,* coyote,* red
fox.*
The forested and brush areas provide greater cover and nesting habitat for a greater
variety of wildlife than does the open grasslands. The water of the creek and its small
impoundments attract wildlife to these areas to quench a thirst, or hunt for other wildlife
drawn to the water. A variety of native bird species utilize the tree and brush canopy to
nest and feed in, including the acorns of the oak trees provide a food source to a wide
variety of bird and mammal species. Common and typical species expected to occur in
these habitats include: red fox, raccoon,* deer,* scrub jays,* common flickers, various
woodpeckers and grey squirrels.
Two rare animal species are known to occur in the project region; the state and federal
endangered San Joaquin kit fox, and the State rare Alameda striped racer.
The San Joaquin kit fix(Vuples macrotis mutica) is listed as endangered by both the State
Department of Fish and Game (DFG) and U.S. Fish and Wildlife Services. This nocturnal
fox has been sighted in the Livermore Valley region west of Collier Canyon Road in 1975
(U.S. F.W.S. 1983). The fox would appear to be moving into the Livermore Valley region
due to the loss of habitat in its historic range in the San Joaquin Valley. The project site
is located just west of the known distribution of the endangered animal. The kit fox
resides in underground burrows with characteristic openings. No kit fox denning sites
were located on the site. The fox prefers to build dens in areas of low to moderate relief
(19°-22°) at or below mid-slope. It is unlikely the San Joaquin kit fox is actively denning
on this site;however,it may on occasion move through the site.
The Alameda striped racer (Masticophis lateralis eurvxanthus) is listed as a State rare
species. This snake is limited to the valleys, foothills and low mountains of the Coast
86123 3-8
3.Vegetation&Wildlife
rTh
Ranges east of the San Francisco Bay and west of the Central Valley in Contra Costa and
Alameda counties. The Alameda striped racer has been sighted in the Mt. Diablo area
approximately ten miles north and east of the site. It is usually associated with chaparral,
but may occur in grasslands, open woods and rocky slopes. Suitable habitat for this rare
snake does occur on the site and it is possible that the snake occurs on the site;however,
the snake was not observed during the field survey.
3.2.2 POLICY REVIEW
The City and State policies do not specifically address wildlife resources. However, the
policies that address the riparian and oak woodland communities would also apply to the
most important wildlife habitat resources.
3.2.3 DEVELOPMENT CONSTRAINTS AND OPPORTUNITIES
The same constraints addressed in the vegetation section apply to wildlife. One additional
constraint would be to maximize wildlife habitat values of designated open spaces, they
should be contiguous and with sufficient buffer areas to minimize impacts associated with
urban encroachment.
As an example, Martin Canyon Creek should be maintained as a wildlife movement
corridor with the greatest buffer areas at the west end of the site where adjacent
developments do not occur. The third tributary and associated woodlands should also be
preserved as a wildlife area connecting with Martin Canyon Creek. Development should
avoid these waterway areas as much as possible and strive not to constrict connection
between the two with housing units and/or roadways. An example of the most efficient
and effective wildlife open space corridor is provided in the vegetation map.
Wildlife constraints are indicated below:
Resource Constraint Rating
Riparian Corridor No Build
Coast Live Oak/California Bay Forest High-Moderate
Annual Grasslands and Chaparral Low-No Constraint
86123 3-9
3.Vegetation& Wildlife
3.2.4 DATA SOURCES
Publications and documents on the wildlife of the Hansen Ranch area were assembled and
reviewed prior to fieldwork. Literature on the wildlife of the region, including their
status and habitat-relationships, was collected from various sources: California
Department of Fish and Game (CDFG 1980), Robbins et. al. (1966), and Brown and
Lawrence(1965).
a
Species that were observed or which tracks or scat was observed on-site.
References
Munz, P.A. and D.D. Keck. A California flora and supplement. University of California
Press,Berkeley and Los Angeles, 1968.
Smith, J.P., Jr. and R. York(eds.). Inventory of Rare and Endangered Vascular Plants of
California, 3rd. ed. Special Publication No. 1, California Native Plant Society, Berkeley,
1984.
California Department of Fish and Game. At the Crossroads, 1980.
. Natural Diversity Data Base. Unpublished, 1985.
. List of designated endangered or rare plants,pursuant to Section 1904, Fish
and Game Code (Native Plant Protection Act), effective 5 Feb. 1982. Unpublished Ms.,
1984.
Cheatham, N.H. and J.R. Haller. An annotated list of California habitat types.
Unpublished manuscript prepared for the University of California Natural Land and Water
Reserves System, 1975.
McMinn,H.E.and E. Maino. Pacific Coast Trees. University of California Press, 1937.
U.S.Fish and Wildlife Service. San Joaquin Kit Fox Recovery Plan, 1983.
Robbins,C.S.et. a1. Birds of North America. Golden Press, 1966.
Brown, V. and G. Lawrence. The California Wildlife Region, Naturegraph Publishers,
1965.
•
•
86123 3-10
4 VISUAL ANALYSIS
4.1 OBJECTIVES AND METHODS
Assessment of visual resources provides for the identification of site characteristics with
aesthetic value which should be preserved or enhanced. Such site features might include
knolls which afford panoramic views, land forms such as significant ridgelines that are
viewed from off-site and contribute to the regional setting, water features, and site
vegetation such as tree groupings and grassland.
Visual quality is a professional judgment which measures the visual sensitivity of a site to
development based on a number of key variables. These factors include observer position,
viewing distance, duration of view, number of viewers, slope aspect, landform, prominent
site features, vegetation and coloration. Visual change to a site due to construction is
considered an impact; it is also a measure of the degree to which the observer is aware of
development within the landscape, and includes the compatibility or conflict of visual
change with the surrounding environment.
Visual impacts of the developed site relate to physical layout of development with respect
to slopes; siting and density of buildings; design and architectural characteristics of the
structures with regard to size, materials and finishes;site grading and landscaping.
In order to retain the visual quality of a site and protect the existing regional setting,
adverse visual impacts associated with development/construction should be avoided or
mitigated. To accomplish this, existing site features must be identified and their
importance established with regard to the regional setting. The Visual Features Map
identifies the following visual site features:
•
86123 4-1
4. Visual Analysis
Knoll: The top of a hill, or the flatland portion of the terrain
surrounded by downward sloping land. Generally, an area with
spectacular, panoramic views of the surrounding area.
Minor ridgeline: The ridge of a hill or group of hills that is distinguishable from
off-site view locations. Ridges often form one of the layers of
the regional background.
Valley: A natural, deep depression in the landscape, formed as the site
drains from higher elevations and steep slopes.
Vegetation community: Natural groupings of vegetation which contribute to the site's
visual character. Oak woodland and grassland are the two
vegetative groupings which give Hansen Hill Ranch visual
character.
The distance from which the site and its visual features is observed is critical in
determination of the visual impacts of construction. For the purposes of this assessment,
views have been classified as foreground, middleground and background.
Foreground
Views which occur within a distance from the observer where details can be perceived; for
example, individual boughs of trees form texture. The distance which comprises
foreground views is generally limited to the areas within 0 to 1/4 mile of the observer.
Middleground
Views which extend from the foreground zone to a distance where form rather than detail
is perceived by the observer; the observer would perceive tree form rather than individual
boughs. For this site's visual assessment, middleground views have been determined to be
from 1/4 mile to 1/2 mile distance from the observer.
Background
Background views are characterized by texture and pattern created by groups of forms;
for example, groups of trees establish texture in the background. Views extend from the
outer limit of middleground (1/2 mile) to infinity.
The Visual Sensitivity Map, following, indicates the visual sensitivity of Hansen Hill Ranch
and the ability of the site to absorb construction/development. These determinations
86123 4-2
4.Visual Analysis
were made through site reconnaissance and the use of aerial photos, site photos, and
topographic maps. A visual sensitivity rating is assigned to each area based on: location
in the foreground, middleground, or background; ability of site slopes and vegetation to
absorb development; orientation of slope (aspect); number of observers; type of visual
experience,and duration of view.
Visual sensitivity ratings of extremely high, medium and low are assigned to the site and
are defined below:
Extremely High: No screening, no backdrop, no ability for area to absorb
development. Development would conflict with site, would be
visible from surrounding residential areas and would be
obtrusive.
High: Little or no screening or backdrop; slopes are generally exposed
grassland. Site has little ability to absorb development which is
prominent in relation to the landscape. Areas are highly visible
from adjacent residential areas or scenic highways; development
would be obtrusive to obvious. Sensitive siting, design and
mitigation would be necessary for a harmonious balance of site
development with the landscape.
Moderate: Limited to moderate screening and/or backdrop; slopes are
mixed grassland and oak woodland. Site has some ability to
absorb development. Areas are visible from adjacent residential
areas and scenic highways; development would be apparent in
relation to the landscape. Sensitive siting, design and mitigation
would be necessary for a harmonious balance of site develoment
with the landscape.
Low: Moderate to heavy screening and/or backdrop; slopes are oak
woodland. Site has the ability to absorb development. Areas are
visble from adjacent residential areas, but development would
not be apparent in relation to the landscape. Sensitive siting,
design and mitigation would be necessary to preserve the
•
86123 4-3
4.Visual Analysis
important visual characteristics of the oak woodland.
Development would be harmonious with the landscape.
4.2 EXISTING CONDITIONS
Hansen Hill Ranch is made up of rolling hills and deeply cut valleys, with elevations
ranging from 470 feet at the northeast boundary(Silvergate Drive)to over 860 feet along
the west border. Variety of elevation, landform, drainage pattern and vegetation
contribute to the visual quality of the site. Figure 4-1 shows views of the site from
Hansen Drive looking north and from Rolling Hills Drive looking south.
The property includes four distinct knolls situated in two rows,nearly equally spaced from
east to west. The two northern knolls are separated by deep valleys, while the two
nearest the site's southwest boundary are separated by a saddle of land. Generally, the
knolls are exposed grassland, however, the northern two are surrounded on three sides,
along their lowest slopes, by oak woodland. Slopes of the northern knolls have north and
east orientation (aspect), and are viewed from many off-site residential locations. The
two southernmost knolls are part of a ridge which is dominant in terms of the site, while
minor with regard to the regional setting. This ridge intercepts views to the site from I-
580(see Figure 4-2).
Views from the site are of the site itself and the surrounding area, extending to the ridges
and hills in the north, to the San Ramon Valley and hills beyond in the east, to I-580 and
the hills beyond in the south and to the rolling hills in the west.
4.3 POLICY REVIEW
The City of Dublin's General Plan policies which relate to visual quality are listed below:
Policies 2.1.4, 3.1 and 3.3 address visual quality concerns for the Extended Planning Area.
Policy 2.1.4(C), states that proposed site grading and means of access, for the siting of
residential proposals, will not disfigure the ridgelands.
Policy 3.1(A) calls for the preservation of oak woodlands, riparian vegetation and open
space. Policy 3.1(C) requires that steep slopes and ridges be reserved as a condition of
86123 4-4
SITE PHOTOS FIGURE 4-1
SOURCE EIP ASSOCIATES
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View looking North from homes along Hansen Drive. ei p L
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SITE PHOTOS FIGURE 4-2
SOURCE EIP ASSOCIATES
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View looking North to site from 1-580.
i
4.Visual Analysis
subdivsion map approval. Policy 3.3(E)restricts structures on the hillsides that appear to
project above major ridgelines. The undisturbed natural ridgelines as seen from the
primary planning area are an essential component of Dublin's appearance as a freestanding
city ringed by open hills. Implementing Policy 3.3(F) uses subdivision design and site
design review process to preserve or enhance the ridgelines that form the skyline as
viewed from freeways or major arterial streets. (For this project,freeways include I-580,
I-680;arterials include Dublin Blvd.,Amador Valley Blvd.,and San Ramon Road.)
Policies 2.1 and 5.6 apply to the Primary Planning area. Guiding Policy 2.1.3(A) states
that abrupt transitions should be avoided between single-family development and higher
density development on adjoining sites. Implementing Policy 2.1.3(B) requires that site
plans respect the privacy and scale of nearby residential development.
Policy 5.6 relates to scenic highways as designated by Alameda County in 1966; these
include I-580, I-680 and San Ramon Road in the Primary Planning Area. Scenic Highways
are routes from which people traveling through Dublin gain their impression of the city;
Policy 5.6 states that it is important to protect the quality of views from these roads.
Policy 5.6(B)calls for design review of all projects visible from designated scenic routes.
Policies which relate to Environmental Resources Management (Section 7) apply to the
entire planning area. Riparian vegetation as an aesthetic resource is protected by Policy
7.1 which requires revegetation of creek banks where construction requires creekbank
alteration.
Policy 7.3 protects oak woodlands. This policy states that where woodlands occupy slopes
that could otherwise be graded and developed, allowable densities should be permitted to
be transferred to other parts of the site. Removal of individual oak trees, however, may
be considered through the project review process.
City policies which relate to visual considerations are restrictive as to the location of new
development. Views from scenic roads are protected, and views to the surrounding
ridgelines from the City are protected.
86123 4-7
4.Visual Analysis
n
4.4 DEVELOPMENT OPPORTUNITIES AND CONSTRAINTS
The site contains strong vegetative patterns and a variety of landforms that, when
combined, give the site its visual character. The degree to which areas of the site are
visually sensitive depends on prominence and visibility of the area from off-site locations.
Prominence and visibility are determined by a number of factors including: slope, aspect,
vegetative screening, and location in the foreground, middleground or background.
Visually sensitive areas are those which are most visible; are seen by the greatest number
of people for the greatest duration of time. Areas viewed from residential communities
would be more sensitive than those areas seen by freeway drivers moving at high speeds.
If, however, the site was within a motorist's cone of vision, a visual impression of the
region could be formed based on the view of the area.
As previously mentioned in this chapter, the site has been studied and evaluated to
determine the degree of visual sensitivity. The Visual Sensitivity Map following page 4-2
shows visual sensitivity ratings which are applied to the site as follows:
Sensitivity Absorption Constraint Rating
Extremely High None No-Build
High Low High
Moderate Moderate Moderate
Low High Low
High constant ratings signal the need for sensitive site planning and design considerations
to mitigate adverse impacts and to allow development to exist harmoniously with the
landscape. Siting, design and mitigation measures which might apply to slopes with
moderate and high visual constraints include:
o Siting buildings below ridgelines, so that building form does not interfere with views
of natural landforms.
o Limiting height of structures.
o Establishing standards for building materials, color and finishes which insure
compatibility with the surroundings.
o Grouping or clustering development to mimic natural tree groupings.
o Establishing landscaping standards which utilize native vegetation.
•
86123 4-8
4.Visual Analysis
o Establishing grading requirements so that excessive cut and fill is avoided.
o Utilizing a multi-level design approach; that is, parking on one level, house on
another,decks used in place of flat,open lawns.
o Preserving prominent knolls as open space/viewing areas.
o Constructing narrow roads to minimize cut and fill.
o Retaining oak woodland and riparian vegetation.
o Stabilizing and replanting soil disturbed by construction.
o Requiring off-street parking to minimize road width.
With sensitive planning and design, many highly constrained areas are developable.
Hillsides define areas of low and high visual access, depending on the observer's position.
Hillsides may actually screen or conceal views and because of their visual prominence,
may provide for the physical integration of building with the landscape. Areas with a high
degree of background or screening also absorb development as compared to areas with
little or no background/screening. Steep slopes direct vision upward to hilltops from many
locations on and off the site. Ridgelines and hilltops are seen against the sky, and cloud
formations then become part of the setting. Existing tree masses may be used to screen
development, and to relate the height, bulk, and mass of single structures to the
landscape. Open space may be used to retain the most sensitive areas, to separate
groupings of structures,and to replicate the inherent structure of the site.
4.5 DATA SOURCES
1. David Gates and Associates, Hansen Hill Ranch Environmental Planning Study,
October 1986.
2. Hardesty Associates, Oak Woodland Preservation and Land Planning: Portola Valley
Ranch, 2nd Edition,March 1984.
3. Kevin Lynch,Site Planning, 2nd Edition, MIT Press, 1971.
4. City of Dublin General Plan, Adopted February 1985.
5. EIP Associates,Fountain Grove Ranch Environmental Assessment, 1980.
6. California Region 5 Forest Service, U.S. Department of Agriculture, Visual Resource
Management Guides--Visual Quality Standard Determination do Application, March
1973.
86123 4_9
•
5 SLOPE ANALYSIS
5.1 OBJECTIVES AND METHODS
Slope analysis identifies areas that are suitable for the construction of buildings, roads,
parking lots and those areas which should remain in open space. Steep slopes constitute a
major constraint to development, as alteration for construction is costly and may lead to
adverse impacts which are damaging to the environment unless properly mitigated.
Grading on steep slopes may increase siltation, damage wildlife and plant habitat, affect
water quality,alter drainage patterns or create undesirable views.
The following Slope and Aspect Map shows aspect and slope for the Hansen Hill Ranch
site. Aspect is the orientation of ground surface or the direction a slope faces. Most of
the slopes on this site are north facing and east facing. Slope on the property is
categorized accordingly: 0%to 10%, 10% to 20%, 20%to 30%,and those slopes in excess
of 30%. These determinations were made using 1:200 scale maps and a tick-strip
measuring system, which identifies slopes based on distance between contour intervals.
Acreages of each slope category were arrived upon by measuring with a planimeter and
calculating the area based on the appropriate conversion for a 1:200 map scale.
SLOPE CATEGORIES
0- 10%
Range
Flat to ten feet of rise per 100 feet of horizontal distance. Such sites are composed of
flat to gently rolling land forms and, where other constraints to development are not
identified, are good for intensive development activity such as building sites, parking
areas and roadways. Minor excavation for development would be necessary at localized
points on slopes of from 5% to 10%.
86123 5-1
5.Slope Analysis
10%-20%
Range
Ten to twenty feet of rise per 100 feet of horizontal distance and are characterized by
rolling terrrain. These sites would be fair for building sites,roadways and parking lots, as
moderate excavation for development is necessary, requiring cut and fill at localized
points.
20%-30%
Range
Twenty to thirty feet of rise per 100 feet of horizontal distance. Slopes of this category
are generally more rugged, with steeply rising terrain. Construction of buildings,
roadways, parking lots and other development is more restricted on slopes in this
category;considerable grading for buildings and surface paving are usually required.
Over 30%
Range
Over 30 feet of rise per 100 feet of horizontal distance. Slopes greater than 30% are
more difficult to build on and normally require higher construction costs for specialized
construction procedures, such as cantilevered sections supported by pier or post
foundations. Where grading for construction is required, cut and fill quantities are apt to
be high.
5.2 EXISTING CONDITIONS
Hansen Hill Ranch is made up of a variety of land forms including rolling hills, ridges,
knolls, and deep valleys. The valleys generally run in a northeast to southwest direction,
resulting in slopes which are exposed to the north and east (see Slope and Aspect Map
following page 5-1).
Slopes on the project site range from isolated areas that are flat to slopes which exceed
50%. Visual examination of the slope map shows the largest slope area to be in excess of
30%. The breakdown for slope categories of the project site are as follows:
86123 5-2
5.Slope Analysis
CM
Slope' Acreage Percent
0-10% 6 Acres 4%
10-20% 43 Acres 29%
20-30% 34 Acres 23%
Over 30% 65 Acres 44%
Total 148 Acres 100%
"David Gates & Associates, Hansen Hill Ranch Environmental Planning Study, October
1986.
5.3 SLOPE&VISUAL QUALITY
The visual character of Hansen Hill Ranch is determined by its vegetative cover and
slope. The site's steep slopes which face north and east are apparent from off-site
locations,particularily developed areas north of the site and east of Silvergate Road.
Areas with steep slopes tend to "absorb" development. Structures placed in areas with
steep slopes assume less visual importance in verticality and mass due to the strong land
form backdrop. That is, if the building is sited below the ridgeline or knoll, it will not
give the appearance of being on a pedestal. Siting structures below high points or
ridgelines retains the prominence of the landform and avoids silhouetting buildings against
the sky.
(For a complete discussion of visual quality,see Chapter 4,Visual Analysis.)
5.4 POLICY REVIEW
Policies of the City of Dublin's General Plan which relate to development on slopes
generally apply to the Extended Planning Area,and are described below:
Guiding Policy 2.1.4(A) allows for the consideration of residential development and
related support facilities on moderate slopes. Implementing Policy 2.1.4(C) states that
approval of residential development in the Extended Planning Area will require that
proposed site grading and means of access will not disfigure the ridgelands.
86123 5-3
5. Slope Analysis
Policy 3.1(B) of the City's General Plan, states that slopes predominantly over 30% will be
maintained as permanent open space for public health and safety. The implementing
policy, 3.1(C), requires the continuation of reserving steep slopes and ridges as open space
as a condition of subdivision map approval.
City policy 3.3(E) restricts structures on the hillsides that appear to project above major
ridgelines. The City values undisturbed natural ridgelines as seen from the primary
planning area as an essential component of Dublin's appearances as a freestanding city
ringed by open space. Policy 3.3(F) implements this policy by using the subdivision and
site design review process to preserve or enhance the ridgelines that form the skyline as
viewed from freeways (I-580, I-680) or major arterial streets (including Dublin Blvd.,
Amador Valley Blvd. and San Ramon Road).
Policy 7.2(B) regulates grading and development on steep slopes; Implementing Policy
7.2(F) restricts development on slopes of over 30%.
Generally the City's Plan restricts development on hillsides in excess of 30%, however,
development is not prohibited by the policies. Slopes viewed from designated scenic
roadways are restricted by City policies, such that the undisturbed natural character must
be retained.
5.5 DEVELOPMENT OPPORTUNITIES AND CONSTRAINTS
Nearly one-half of the site is made up of slopes which are greater than 30%.
Development on these slopes would require special construction considerations. Slope
analysis identifies areas subject to adverse impacts, and signals a need for appropriate
mitigation. Slope analysis also recognizes areas that are most suitable for development.
Steep slopes are inherently more expensive to develop, requiring special construction
practices such as:
o The construction of retaining walls to reduce areas of graded surface
o Earth controuring to achieve lesser slope gradients
o Removal and recompaction of areas prone to sliding
o Use of grade beams and piles in lieu of conventional foundations
86123 5-4
5.Slope Analysis
o Altering of natural drainage patterns
o Construction of water runoff collection facilities
o Provision of soil binders
o Installation of special utility sytems to service development.
Construction constraints for the four previously identified slope categories are applied to
the site as follows:
Slope Constraint
0-10% None-Low
11-20% Low-Moderate
21-30% Moderate
Over 30% High
While slopes of over 30% are considered to be highly constrained, they are capable of
supporting limited development, provided special construction techniques are utilized and
detailed grading and drainage studies are completed.
Figure 5-1 shows that the steepest slopes on the site are in a fan-like configuration which
surround prominent knolls on three sides. The less constrained slopes generally occur on
top of knolls and along the site's south boundary. Steep slopes on this site are also the
most vegetated, while the less-steep slopes are grassland. Therefore,development on less
constrained slopes would be visually prominent(see Chapter 4,Visual Analysis).
Development opportunities on the Hansen Hill Ranch site occur primarily on the flat to
rolling portions of the site, or those areas with slopes ranging from 10% to 20%. Areas
with slopes from 20% to 30% could accommodate development if special construction
techniques were employed. Steep slopes (greater than 30%) may be used to visually
screen buildings from critical viewpoints. Large areas of steeply sloping terrain would be
most suitable for land uses which do not require extensive construction, thereby reducing
potential impacts. Such land uses include: common open space, hiking areas, vegetative
buffers, wildlife habitat, preservation of natural drainage, and viewpoints. Grouping of
buildings should be considered in areas which are made up of minor slopes surrounded by
steep slopes.
86123 5-5
5. Slope Analysis
5.6 DATA SOURCES
The following books, reports and documents were utilized during preparation of this
section of the report:
1. EIP Associates, Fountain Grove Ranch Environmental Assessment, March 1980.
2. David Gates & Associates, Hansen Hill Ranch Environmental Planning Study, October
1986.
3. City of Dublin, General Plan 1985 - 2005, Adopted February 1985.
4. Kevin Lynch, Site Planning, MIT Press, Second Edition, 1971.
86123 5-6
6 NOISE
6.1 OBJECTIVES AND METHODS
Environmental noise is measured in decibels. The dBA,or A-weighted decibel, refers to a
scale of noise measurement which approximates the range of sensitivity of the human ear
to sounds of different frequencies. On this scale, the normal range of human hearing
extends from about 3 dBA to about 140 dBA. A 10 dBA increase in the level of a
continuous noise represents a perceived doubling of loudness; a 2 dBA increase is barely
noticeable to most people.
Human response to noise is subjective, and varies considerably from individual to
individual. Effects of noise, at various levels, can range from interference with sleep,
concentration, and communication, to physiological and psychological stress, and hearing
loss. The sound level of speech is typically about 60 to 65 dBA. Sleep disturbance occurs
when interior noise levels exceed 40 to 50 dBA.
Environmental noise fluctuates in intensity over time and several commonly used
descriptors of time-averaged noise levels are in use. The City of Dublin uses CNEL, the
community noise equivalent level, as the measure of noise acceptability. CNEL is the 24-
hour average of the noise intensity, with a 5 dBA "penalty"added for evening noise (7:00
pm to 10:00 pm) and a 10 dBA"penalty" added for nighttime noise (10:00 pm to 7:00 am)
to account for the greater sensitivity to noise during these periods.
Existing studies were examined for information which would characterize the noise
environment of the project site and policies of the City of Dublin as they affect land use
in various noise environments.
86123 6-1
6.Noise
6.2 EXISTING CONDITIONS
Traffic is the primary source of continuous noise in Dublin and its environs. In 1983,
Charles M. Salter and Associates, acoustic consultants under contract to the City of
Dublin, mapped CNEL contours for existing and future (year 2005) traffic noise; these
maps were later incorporated into Dublin's General Plan(see Figures 10 and 11, pages 38
and 39, respectively, of that document and Figures 6-1 and 6-2 of this document).
Comparison of the map of existing CNEL contours with a map of the project site shows
that the CNEL in a strip of land (ranging in width from 0 to 400 feet) at the southern
boundary of the site is exposed to a CNEL greater than 60 dBA. The remainder of the site
has a CNEL less than 60 dBA.
6.3 POLICY REVIEW •
It is the policy of the City of Dublin to employ a Land Use Compatibility Table(see Table
6-1 below) as a guide for making decisions on prospective land uses in relation to noise
sources and to determine noise mitigation needs. Table 6-1 shows that when the CNEL is
greater than 60 dBA, residential uses on that site become"conditionally acceptable", that
is acoustic analyses and installation of noise insulation become mandatory before
construction can be authorized.
6.4 OPPORTUNITIES AND CONSTRAINTS
At present, the use of the project site for the construction of single family homes would
be "normally acceptable" under the City of Dublin's land use compatibility guidelines,
except for the southern-most portion of the property (a strip varying in width from 0 to
400 feet)which would be"conditionally acceptable"for residential use. By the year 2005,
the strip of conditional acceptability will have grown in width to between 600 and 800
feet,due to the increase in traffic expected on I-580 and San Ramon Road.
In planning for project construction, provision should be made for the acoustic analysis of
the project structures and the installation of any additional noise insulation required.
6.5 DATA SOURCES
The Dublin General Plan was consulted for all information contained herein, regarding
existing and future noise levels on the project site, and the City's land use compatibility
guidelines.
86123 6-2
s7
1983 NOISE EXPOSURE CONTOURS FIGURE 6-1
SOURCE:CITY OF DUBLIN GENERAL PLAN
FEET
0 1000 2000 4000
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2005 PROJECTED NOISE EXPOSURE CONTOURS FIGURE 6-2
SOURCE'CITY OF DUBLIN GENERAL PI.
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0 1000 2000 .000
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6. Noise
• TABLE 6-1
LAND USE COMPATIBILITY FOR COMMUNITY NOISE ENVIRONMENTS
Community Noise Exposure
CNEL (dBA)
Lend Use Category SCC
� En 65 qn 45 gn g5
Residential a a b b c d d
Motels and Hotels a a b b c c d
Schools, Churches, a a b b c c d
Nursing Homes
Neighborhood Parks a a b c d d d
Offices: Retail/Commercial a a a a b c d
Industrial a a a a b c c
a. Normally Acceptable - land use is satisfactory, buildings need no special noise
insulation.
b. Conditionally Acceptable - new construction should be undertaken only after acoustic
analysis and installation of noise insulation.
c. Normally Unacceptable - new construction should be discouraged. If construction
does proceed, acoustic analysis and insulation required.
d. Clearly Unacceptable - new construction should not be undertaken.
Source: Dublin General Plan.
86123 6-5
7 ARCHAEOLOGICAL RESOURCES
Foothill areas in proximity to the proposed project site have yielded archaeological sites.
The California Archaeological Inventory has been contacted and asked to conduct a
literature survey of the project area. A review of the records will determine the
archaeological sensitivity of the site and if any prehistoric or historic resources have been
recorded within or adjacent to the Hansen Hill Ranch site.
86123 7-1
8 PUBLIC SERVICES
8.1 OBJECTIVES AND METHODS
The objective of this section of the document is to report on the availability and capacity
of existing services that could be extended to the site and to residents of the project. To
the extent applicable,site planning constraints related to services are identified as inputs
for Phase 2 of this study, which will include submittal of a specific site plan by the
applicant. In other cases, the information is more pertinent to Phase 3, when the EIR on
the project will be prepared.
EIP has contacted the service providers to obtain information about current service
levels, but the analysis of project impacts cannot be completed until Phase 3 when the
specific number of units proposed for the site has been determined.
EIP has not developed new information at this stage regarding water and sewer services.
The project engineer, Wilsey Ham Associates, has prepared preliminary information on
existing utility systems which is described in the Environmental Planning Study on file
with the City. The Dublin San Ramon Services District (DSRSD) is currently reviewing
the sewer and water service requirements for the property. The following information is
excerpted from the Wilsey Harn study.
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 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. Before the development of Silverage Highlands,
86123 8-1
8. Public Services
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 tank. Subsequently, all the above mentioned development became subject to an
agreement with DSRSD. The 4-party agreement as it is known(which did not include the
Hansen property)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 Drive tank. The
location of this main on the Hansen property has not been determined.
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.
Several alternatives exist for the Zone IV facilities. Further discussions with DSRSD will
be needed to determine a final water Zone IV proposal.
Regarding sanitary sewer, the existing sanitary sewer system provides adequate capacity
at relatively convenient service connection points in Silvergate Drive and 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. (Source: Wilsey do Ham)
8.2 EXISTING CAPACITY AND PROXIMITY
8.2.1 FIRE PROTECTION
Fire protection is provided by the DSRSD Fire Department. The Department has 38 sworn
staff and 12 volunteer fire fighters and responded to about 1,250 calls during the past
80123 8-2
8.Public Services
year. The nearest fire station is at 7494 Donahue, near the corner of Amador Valley Blvd,
which is approximately 0.9 miles driving distance from the site.
The houses currently under construction north of Hansen Hill Ranch define the upper
boundary of adequate response time from the fire station on Donahue. These homes are
approximately 1.5 miles from the station. To maintain a similar distance at Hansen
Ranch, homes could be located about 400 feet into the City's extended planning area, or
800 feet short of the property's western boundary. Chief Phillips has suggested that any
homes located further up the hill should be equipped with internal sprinkler systems.
Chief Phillips further indicates that project roads should not have greater than a 15%
slope and should be of standard width as provided in the City's zoning code to permit turn-
around space for trucks.
8.2.2 POLICE
The City of Dublin provides police protection service through a contract with the
Alameda County Sheriff Department. The City is patrolled as a single beat and the newly
constructed units north of Hansen Ranch are patrolled under the City's existing
arrangement with the Sheriff.
The City Police Department reviews all project proposals and provides guidance on ways
to maximize security in residential design. The Department's concerns focus on lighting,
the orientation of windows, the design and placement of locks and the like. However, the
design considerations are not codified, so it will be necessary to submit the preliminary
design to the Department at the end of Phase 2 to obtain police input.
8.2.3 SCHOOLS
The site is within the Murray School District, which has the Neilsen Elementary School
nearby the site on Amarillo Street. The district has three schools closed at the present
time due to falling enrollments; one of which, the Dublin School adjacent to the I-680
freeway, is leased to a private school. No plans exist currently to return Dublin School to
the public school system, but it is not clear whether Neilsen School can continue to
accommodate all the children in Dublin west of 1-680.
86123 8-3
8.Public Services
Neilsen has a capacity of 647 students in its permanent facilities and an additional 60
students in portable classrooms. Current enrollment is 610 students,leaving capacity for
approximately 100 additional children. At the district's average student generation rate
of 0.2 students per dwelling unit, Neilsen can accommodate children from an additional
500 homes. Approximately 400 homes are under construction north of Hansen Ranch
which will likely fill about 80%of this remaining capacity. However,space is available at
Neilsen School for additional portable classrooms if necessary; therefore, elementary
school capacity should not be a constraint for development at Hansen Ranch.
8.2.4 SOLID WASTE
Solid waste disposal in Dublin is provided under exclusive contract by the Oakland
Scavenger Company. The waste is delivered to the Altamont Landfill, located east of
Livermore. This landfill is estimated to have a remaining capacity of 34 years, and does
not pose a constraint to development in Dublin. Other than providing adequate access for
the garbage trucks,no design requirements exist for solid waste disposal service.
8.2.5 PARKS
The City of Dublin provides park and recreation services in the neighborhoods near the
site. The nearest park is May Park on Plata Way adjacent to Neilsen School. A new five
acre park is planned on Padre Way as part of a new subdivision. In addition, the City has
Shannon Park and community center approximately three-quarters of a mile from Hansen
Ranch. The City operates a wide variety of recreation programs out of the community
center and also at Neilsen School. The General Plan does not designate any additional
parks for this part of town, and does not provide any standards for the amount of park
acreage needed per unit of population. The City does have other provisions, however, for
the applicant to dedicate park land or to pay park fees in lieu of park dedication (see also
Section 10, Fiscal Analysis for more discussion of park dedication alternatives).
8.3 DEVELOPMENT OPPORTUNITIES AND CONSTRAINTS
Based on preliminary analysis no major public service constraints exist for the property.
Considerably more engineering analysis is needed to determine the water and sewer utility
systems to design for. An,- such requirements will need to be addressed in Phase 2 as the
project is designed. However, the above analysis of other services suggests several
considerations for the site design.
86123 8 4
8. Public Services
To facilitate adequate fire protection and emergency access, the internal roads should
have less than 15% slope and should be of standard width as provided in the City's building
code. If a separated road design is adopted, adequate turning locations should be provided
to ensure that fire trucks have sufficient mobility once on the site. Further, at least one
secondary access should be provided to streets adjacent to the site to ensure that
emergency vehicles are not prevented access to all parts of the site due to blockage of
the main collector street. Homes located in the western 800 feet of the site may need to
be outfitted with inside sprinkler systems due to the distance from the fire station.
Given the general nature of these recommendations and the various design options
available to achieve them, the public service issues should be considered a low constraint
to development on the site.
8.4 DATA SOURCES
Fire Protection: Phillip Phillips, Fire Chief, DSRSD, telephone conversation, November
11, 1986.
( Police Protection: Sergeant Difranco, City of Dublin Crime Prevention Officer, telephone
conversation, November 17, 1986.
Schools: Heinz Gewing, Assistant Superintendent, Murray School District, telephone
conversation, November 19, 1986
Solid Waste Disposal: Paul Rankin, Dublin City Manager's Office, telephone conversation,
November 17, 1986.
Woodward-Clyde Consultants, Review of Altamont Landfill Design Capacities, December
17, 1985
Parks: Diane Lord, City of Dublin Recreation Director, telephone conversation, November
17, 1986.
86123
9 FISCAL ANALYSIS
9.1 OBJECTIVES AND METHODS
The purpose of this section is to introduce some key concepts regarding the kinds of
cost/revenue considerations that must be addressed in the final evaluation of the Hansen
Ranch project. The service costs and public revenues discussed below are based solely on
current average costs for the City of Dublin and the Dublin San Ramon Services District
(DSRSD) and will need to be revised when a specific project design has been developed.
The discussion also presents planning considerations related to involvement of the East
Bay Regional Park District (EBRPD) in the project and the overall requirements for
LAFCo review of the annexation proposal.
9.2 COST ESTIMATES FOR CITY SERVICES
At this preliminary stage in the project design process, it is not possible to project
accurately the costs that may be incurred by the City of Dublin and by DSRSD. It is
necessary to know the number of dwelling units, the type of units, and the site
configuration to obtain service cost estimates from the agencies. However, for the
purposes of illustration, average cost factors have been calculated which indicate the
level of services provided to the average house in Dublin.
The primary services provided to the site by the City of Dublin are police protection,
recreation programs and street maintenance. The Community Development Department
also provides planning, design review, and project approval processing services, but the
public cost for these services is offset by plan check fees, building permit fees and other
fees charged to the private developer. The current average costs for providing police and
recreation services per resident in Dublin are $88.88 and $20.32, respectively. Average
street maintenance costs have been estimated at $6,424 per road mile. Based on
preliminary discussions with agency representatives, it does not appear that a project at
86123 9-1
9.Fiscal Analysis
i1
Hansen Hill Ranch would require an above average level of service. Therefore,until more
specific service needs assessments can be done, the average costs appear to be reasonably
conservative estimates of public costs.
DSRSD provides water, sewer, and fire protection services. Costs for the first two have
not been estimated pending further development of the design for the utility system. It
should be noted, however, that DSRSD generally requires that private developers pay the
bulk of the costs for installing new infrastructure. Operating costs are recouped through
charges to the users. The average annual cost of fire protection in Dublin is about $480
per household. It is likely that the costs of extending service to Hansen Hill Ranch will be
substantially less, because an existing fire station and equipment will respond to calls
from project. However, the need for additional manpower or equipment cannot be
determined until the project design has proceeded further.
9.3 REVENUE THRESHOLDS
Development of the project will increase the property tax base on the site. The increase
in property tax revenues for various service agencies will change with annexation from
the current distribution. This is because the City will assume responsibility for certain
services and will therefore receive a portion of the tax from the site that it does not now
get. The allocation to other agencies will also be adjusted accordingly. In order to
estimate the future tax distribution, data from an adjacent tax code area in the City of
Dublin has been obtained. The distribution is shown in Table 9-1. The principal agencies
who receive revenues are the County of Alameda with 31.04% of the total, various
education agencies, including the Murray School District, with a total of 29.04%, DSRSD
with 21.23% and the City of Dublin with 6.94%. If this distribution is similar to that
actually established for Hansen when it is annexed, a $100,000 dollar home would
generate, for example, $69 per year for the City of Dublin and about$212 for DSRSD.
The project would likely generate other revenues for Dublin. Residents of the project
would make retail purchases in town and the City would receive sales tax revenues from
these transactions. Currently, Dublin receives about $253 per capita per year in sales
taxes and it is likely that new residents living at Hansen would have similar spending
patterns.
86123 9-2
•
9. Fiscal Analysis
TABLE 9-1
PERCENT DISTRIBUTION OF NON-BOND
PROPERTY TAX LEVY
TAX CODE AREA 26001
Agency Percent
Alameda County 31.04%
Dublin San Ramon Services District 21.23
City of Dublin 6.94
Educational Agencies 29.04
County Library 5.00
Flood Control 2.52
Air Pollution Control District 0.23
Mosquito Abatement 0.15
BART 0.67
East Bay Regional Parks District 3.20
Alameda County Resource Conservation 0.03
Total 100.00%
Source: Alameda County Auditor's Office
The City would also receive subventions from the state based on the increase in
population on the site. The size of these subventions has varied considerably in recent
years, but the current average revenue for the Motor Vehicle in lieu fee and cigarette tax
is $37.80 per capita.
86123 9-3
9.Fiscal Analysis
The other major revenue source that would be applicable to Hansen Ranch is the utility
franchise tax charged to electric, gas, garbage and cable television franchisers.
9.4 POSSIBLE TRANSFER OF OPEN SPACE TO EBRPD
The City of Dublin is concerned about maintenance of public open space that may be
included in the project. If the City is not to assume responsibility for this function, at
least two other possibilities may exist. The project Homeowners Association could
assume responsibility or the land could possibly be dedicated to EBRPD which would then
maintain it. Based on recent EBRPD reports, it is estimated that annual maintenance
costs could range from $15 to $50 per acre per year. At the higher figure, 50 to 75 acres
of the site could be maintained for$2,500 to$3,750 per year.
At the completion of Phase 2, when the site design has been completed, EBRPD has
requested that the City submit a letter formally requesting EBRPD to consider accepting
the site as part of the regional park system. The following discussion describes current
District plans for park facilities in the vicinity of the project site and presents several
( considerations pertinent to the design phase of the project to enhance its usefulness to
EBRPD.
EBRPD provides a variety of types of park areas. Regional Wildernesses are a minimum
of 3,000 acres, Regional Parks are 500 acres, Regional Preserves and Regional Recreation
Areas are each about 100 acres. By itself, Hansen Ranch is too small to be designated a
wilderness or park.
Regional Preserves are intended to protect features of outstanding elements of natural or
historical significance. The criteria for preserves include locations of natural wonder or
scientific importance, the presence of significant historical or cultural tradition, or
possession of regional open space values. It is doubtful in the case of Hansen Ranch
whether significant natural, scientific, or cultural resources are present. Certainly the
site exhibits good open space values, but the minimum size for a preserve would leave
only one-third of the site developable.
The same size criteria applies to Recreation Areas, but the most important criteria
address the intensity of use and the availability of "proven" recreation resources. It is
•
86123 9-4
9.Fiscal Analysis
possible that such a recreation site could be developed at Hansen, but this option would be
relatively expensive in terms of both development and maintenance of the area and would
not necessarily be consistent with the intent of Dublin to simply provide for public
stewardship of the open space in the project.
The most attractive option in terms of current District Plans relates to the regional trail
system in the area. EBRPD Board of Directors received in March 1986 a feasibility report
for developing a major regional park on the Sunol and Pleasanton Ridges. This location is
directly south of Hansen Ranch across I-580. The study concluded that a 9,000 acre park
was feasible, and the recommended boundaries extended north to Devaney Canyon just
south of the project site at I-580. The 1980 EBRPD Plan also calls for a trail linking the
Sunol Ridge with Las Trampas Regional Wilderness. The proposed trail route would pass
through Little Hills Recreation Area, the Bishop Ranch Land Bank area located west of I-
680 and Cull Canyon Recreation Area. This last area is just east of Castro Valley, and
would pull the trail far west of the Hansen Ranch site. Otherwise, Hansen Ranch is on a
straight line between Las Trampas and Sunol.
The shape of the site and its proximity to the major north-south ridge lines in the area
suggest that it could provide a link with this proposed trail system, perhaps as an access
trail route from the urban area of Dublin to the main Las Trampas-Sunol Ridge. The
primary difficulty is the lack of access across I-580 to the at this particular location.
This may be one reason behind the District's plan to swing the trail west to Cull Canyon.
Much further study and discussion with EBRPD is necessary to determine if the trail
system is feasible.
In terms of the site design, if the site is to be recommended as a trail spur, an east-west
corridor should be maintained from either Silvergate or Hansen Drive through the site's
western boundary toward Donlan Ridge. Limited parking at the trailhead will probably
also be necessary.
One logical alternative to dedication to EBRPD would be to require the project
homeowners association to pay for maintenance of the open space on the site. Just as an
example, if 75 acres are left in open space and 75 homes are built on the remaining land,
the average annual cost per home would be $50, or about $4 per month. If more homes
86123 9-5
9.Fiscal Analysis
are built, the cost per unit would be even less. Alternatively, the City could support the
creation of a Landscape Maintenance and Lighting District. The cost per dwelling unit
would be similar to that for the homeowners association.
9.5 REVIEW OF LAFCO REQUIREMENTS.
LAFCo authority to review and approve annexations is provided by the Knox-Nisbet Act
of 1965 (Government Code 54773 et seq.). LAFCo is required to consider a number of
factors in reviewing annexation proposals. The primary considerations include:
o population,land use,projected growth in the area,
o the needs,cost and adequacy of governmental services,
o .the effect of the proposal on adjacent areas and local government structure
within the county,
o effect on agricultural preserves and open space uses,and
o conformity with the city and county general plans and the sphere of influence of
the city.
Most of these items will be addressed in detail in Phase 3 of the study when a specific
project proposal is evaluated. However, it may be noted that the site does lie within the
sphere of influence of the City of Dublin. The County General Plan designates the site
for agricultural uses but the City General Plan designates most of it for residential uses,
with the creek portion reserved for open space. Therefore, the proposal to annex the site
to Dublin for the purpose of developing residential uses is generally appropriate to the
institutional setting. Please refer to Section 10 below for further discussion of the
planning and land use issues related to the site.
9.6 OPPORTUNITIES AND CONSTRAINTS
At this time, the fiscal characteristics of the site do not appear to establish any
significant constraints to development.
In terms of site opportunities, if dedication of the open space on the site to the East Bay
Regional park District (EBRPD) is desired, the open space should be of a linear character
extending from one of the roads at the eastern end of the property through to the western
•
86123 9-6
9. Fiscal Analysis
end, to permit development of a trail. Consideration should be given to providing a small
parking area for people using the trail.
9.7 DATA SOURCES
City of Dublin, Preliminary Budget and Financial Plan, Fiscal Year 1986-1987, June 26,
1986
Dublin San Ramon Services District, Budget 1986-1987, June 20, 1986
East Bay Regional Park District, Master Plan-1980
The Planning Collaborative, The Ridgelands Regional Park Feasibility Study, March 1986.
Thomas Lindenmeyer, EBRPD Land Stewardship, telephone conversation, November 11,
1986
Bruce Kern, Alameda County LAFCo, telephone conversation, November 19, 1986
•
86123 9-7
10 LAND USE
10.1 OBJECTIVES AND METHODS
The key objective of this section is to identify those planning policies in the City of
Dublin General Plan that are applicable to project site development, and provide a
preliminary assessment of those policies as they relate to the project site. Not unlike
many General Plans, the Dublin Plan contains several statements that are broad and
generic in nature, and subject to a range of interpretation. Further, some implementing
ordinances and guidelines, which could provide greater specificity regarding the actual
intent of the planning policies, have yet to be adopted, precluding the opportunity for
precise identification of the degree of policy applicability. Therefore, this analysis will
attempt to both identify policies and provide a preliminary policy interpretation.
Methods of analysis employed in this section include review of relevant City of Dublin
planning documents, particularly the City's General Plan, review of City of Dublin staff
reports regarding development of the project site, review of project sponsor documents,
discussions with members of both the City of Dublin and County of Alameda Planning
Departments, and discussions with project sponsor consultants. This document review and
discussion period serves as the basis for the contents of this section.
10.2 SITE HISTORY
The project site is located on the western edge of the City of Dublin, and is a part of the
larger Tri-Valley area generally comprised of the communities of Dublin, San Ramon,
Pleasanton, and Livermore. Prior to the 1850s, the Tri-Valley area was populated by
Native Americans, who relied upon hunting and gathering activities to sustain their
culture for many years. The Dublin area was first settled by non-natives in the 1850s,and
by the 1870s was part of a larger homesteading settlement near the transcontinental
railroad. From roughly that period to the 1950s, the Dublin area was a productive
86123 10-1
10.Land Use
agricultural center. At the beginning of this agricultural period, the Hansen family
purchased the project site, and used it for agricultural purposes. From the 1950s to
roughly 1980, the area gradually became a community exporting labor to jobs outside the
Tri-Valley area. Since 1980, the Dublin area has grown to form part of an emerging
regional employment center.
Consistent with the Dublin area's historical role as an agricultural area, agricultural
activity, in this case in the form of cattle grazing,has been a predominant activity on the
project site for several years, although there is evidence on the eastern portion of the
project site that orchard crops were cultivated at some point in the past. Prior to that
time, and assuming no dramatic change in landscape characteristics, the site may have
served as hunting grounds for local Native Americans due to the presence of substantial
habitat cover on the site. A small, now dilapidated house is located on the extreme north-
central portion of the site. The present effort to convert the site from agricultural to
urban uses appears to be the first such effort to alter historical uses on the site.
10.3 CURRENT APPLICABLE ORDINANCES AND POLICIES IN THE PRIMARY AND
EXTENDED PLANNING AREAS
This portion of the section provides an overview of major features of the Dublin General
Plan, information on population and housing growth reflected in the plan for the
remainder of the century, and a summary of current and planned land use designations in
the project vicinity.
OVERVIEW OF THE DUBLIN GENERAL PLAN, AND PLANNED GROWTH
The City of Dublin, incorporated in 1982, is approximately 4.1 square miles in area. The
City's 1985 General Plan is the main planning policy document in the City, while the
City's Zoning Ordinance is the key land use regulatory mechanism. The General Plan
identifies a Primary Planning Area (PPA) which includes the 3.8 square mile area that
formed the original incorporated area of the City, as well as a 0.3 square mile area of
previously unincorporated land near the western hills. The PPA is the main area where
General Plan policies are more than schematic in nature. The City has also identified a
15.6 square mile Extended Planning Area (EPA) that "bears relation to its planning"
pursuant to Government Code Section 65300. The EPA is largely undeveloped, and is
86123 10-2
10.Land Use
generally characterized by steep slopes and oak woodlands to the west of the City, and
gently sloping grasslands east of the City. The western segment of the EPA, which
contains a portion of the project site, is approximately 5.3 square miles in area, and is
shown in the Figure 10-1.1 The PPA and EPA together comprise approximately 16 square
miles, and also comprise the City's entire Sphere of Influence(SOI)area.
The SOI contained an estimated population of approximately 17,600 people in 1985,
according to the Association of Bay Area Governments (ABAG), as documented in their
report, Projections '85. The Dublin area is projected by ABAG to increase to 40,500
people by the end of the century, a 130% increase. ABAG estimates that the number of
households in the SOI will increase from 4,800 in 1985 to 12,250 by the year 2000, an
increase of 7,450 households, or 155%. In terms of comparison, Alameda County is
projected to experience a 15% increase in population, and a 20% increase in household
growth over the same time period. As noted in the City's 1985 Housing Element of the
General Plan, only about 160 acres of non-commercial land remained undeveloped in the
PPA, including several surplus school sites. All acreage identified as undeveloped were
inf ill parcels, in that these parcels were contiguous to existing developed land. Inherent
in projections of growth is the apparent assumption that future development will occur on
remaining undeveloped parcels in the PPA, on redeveloped parcels in the PPA, and in the
EPA.
CURRENT AND PLANNED LAND USE IN PROJECT VICINITY
As noted above, the project site is used for cattle grazing. The County of Alameda
General Plan designation for the site is Agricultural. The County's Zoning Ordinance
identifies the land for exclusive agricultural activity, while allowing one dwelling unit per
100 acres, resulting in a maximum of one unit on the project site.2 Current land use
activities in the project vicinity include low-density residential development on the north,
east, and south, the Valley Christian Center to the south, and vacant land planned for
medium density housing to the northeast. Several of the parcels immediately to the west
and north of the project site are currently in Williamson Act agricultural land contract
status, which provides tax savings to contract holders in exchange for guarantees to retain
land in agricultural production for a period of ten years. Renewal is automatic on an
annual basis unless the contract holder elects to serve notice that the contract will not be
renewed. Non-renewal will result in contract termination after a ten-year period. The
86123 10-3
LAND USE PLANNING CHARACTERISTICS
I
I
i
FEET
0' 500 1000 2000
DUBLIN GENERAL PLAN DESIGNATIONS
Project Site
ElSingle -Family Residential
(0.9-6.0 Units per Acre)
Medium -Density Residential
L-2d (6.1-14.0 Units per Acre)
Open Space; Stream Corridor
FIGURE 10-1
1
SOURCE: CITY OF DUBLIN GENERAL PLAN INS -2005
i
II
MILES
0 '/i 1 2
EXTENDED PLANNING AREA POLICIES
Project Site
I
Primary Planning Area (PPA) Boundary-
.
i
I
L. j Sphere of Influence Area
10. Land Use •
only known parcel in the project vicinity that is in non-renewal status is the Nielsen
parcel,which is in the first year of the termination period.3
The project site is segmented by the PPA-EPA boundary line, and is one of only two
parcels in the western portion of the City that is segmented, with the other parcel being
the Nielsen property to the northwest of the project site. As part of the General Plan
refinement study being conducted, consideration should be given to alignment of the PPA-
EPA boundary line to be coterminous with property lines in the project vicinity, as is
typically done as part of planning and zoning studies, which attempt to avoid the splitting
of parcels into multiple categories. This could be achieved as part of a project sponsor
response to a major City policy providing that residential development in the EPA be
based on an assessment of location, extent, and density, predicated on the availability of
public services and General Plan refinement studies.
The western portion of the site in the EPA is approximately 70-75 acres,or about one-half
of the project site.4 Further, the EPA portion of the site comprises about 2%of the City's
western EPA, which extends approximately 3.25 miles west of the PPA boundary line. As
shown at page 10 of the City's General Plan, up to 70%of the EPA's western portion has
limited development potential, with slopes of 30% or greater. The remainder is identified
as "open land with development potential,"5 which appears to mean low-density
residential and residential support uses on moderate slopes, with multi-family density
housing considered on "flatter" land.6 A comparison of project sponsor information on
slopes in the EPA portion of the project site and General Plan documents suggest that the
amount of land with slopes of 30% or greater on that portion of the site is substantially
greater than documented in the General Plan.7 Assuming that other portions of the EPA
currently designated as having slopes of less than 30% would also be similarly compared,
the actual growth potential in the 5.3 square mile western EPA area could be substantially
less than that shown in the General Plan.
PPA Buildout Potential
General Plan designations for the PPA portion of the project site,as shown in Figure 10-2,
include Open Space/Stream Corridor, Single-Family Residential(0.9 to 6.0 units per gross
acre), and Medium Density Residential(6.1 to 14.0 units per gross acre). The majority of
surrounding areas to the north, east and south are designated Single-Family Residential.
86123 10-5
..,..
.....
LAND USE CHAbACTERISTICS FIGURE 10-2
SOURCE: EIP ASSOCIATES: DAVID GATES&ASSOCIATES
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'% Project Site S Single Family Residential Service Area Zone 4 Strata
(Water Pressure Zone)
=
ill Dublin City Limit Line VACANT Undeveloped Lands IN Minimum Elevation Suitable for
L__1 Zone 4 Tank(Elev. 1015 Ft.)
IIPrimary Planning Area(PPA)Boundary Line n
West of line is Extended Planning Area(EPA) Preferred Zone 4 Tank Site
p Agricultural Preserve Lands AL Possible Alternative Zone 4
Tank Site
AG Agricultural/Grazing Lands g3 Private Temporary Reservoir
This is current use of Project Site and
amacent oarcets in unincoroorateo area.
as well as aesigionation aooiiec to:nose ® Existing Tank
Oarceis in County of Aiameaa Genera,Plan
ano Zoning Orainance. - * •
Existing Water and Sewer Lines 0 Private Temporary Pump Station eip L..
1E:
10.Land Use
The Open Space/Stream Corridor designation continues to the east of the site, while the
Medium Density Residential designation is applied to parcels to the northeast of the site.
The General Plan, at pages 7-8, has identified three areas on the project site within the
PPA that provide greater specificity to the land use designations described in the previous
paragraph. The three areas are generally described as follows, using site numbers from
the General Plan:
No.of
Site No. Acres Unit Range Location
5 4 24-32 Extreme northeast corner of site.
6 7 7-20 East of Christian Center,abutting southern property
line.
T 6 6-20 Abutting property line north of Christian Center.
Calculation of site areas was conducted by EIP Associates as part of this analysis, using
the three criteria of acreage not in riparian corridors, not in oak woodland areas and not
in areas with slopes of 30%or greater.8 This effort resulted in the following acreages for
the three sites:
General Plan
Site No Acreage EIP Acreage
5 4 2.0
6 7 12.7
7 6 17.3
Totals 17 32.0
A comparison of the two different density designations for the project site, found in
Figure 1 and at page 8 of the General Plan, and associated dwelling unit totals, along with
application of those two density designations to the two acreage totals, appears below in
Table 10-1.
Based on existing General Plan designations for the site, development potential on the
PPA portion of the project site could be 35-208 units. The wide range in the number of
dwelling units that could be built on acreage without the three aforementioned constraints
86123 10-7
10.Land Use
l '
TABLE 10-1
PPA ACREAGE WITH LESS THAN MAJOR POLICY CONSTRAINTS
AND RANGE OF DEVELOPMENT DENSITIES
No.of Acres No.of Units
Site-NI: Plan Ern Density Range Plan Etn
5 4 2.0 6.0-8.0/gross ac.1 24-32 12-16
6 7 12.7 1.0-2.9 7-20 13-37
7 6 17.3 1.0-3.3 6-20 17-57
Totals 17 32.0 37-52 42-110
5 4 2.0 6.1-14.0/gr.ac.2 24-56 12-28
6 7 12.7 0.9-6.0 6-42 11-76
7 6 17.3 0.9-6.0 5-36 16-104
Totals 17 32.0 35-134 39-208
1Densities for site stated at page 8 of the General Plan.
2Densities for site stated in Figure 1 of General Plan.
does not, however, provide any insight with respect to other constraints such as, for
example, major ridgeline retention or grading and geologic considerations. These and
other factors could act to increase or decrease the number of potential units that could be
developed in the PPA. Further, the number of potential units does not provide any insight
into the amount of identified acreage that can be altered, suggesting that there is
considerable potential to mitigate development impacts through use of, for example,
clustering and attached units, and incorporation of guidelines to reduce the amount of
acreage actually covered with dwelling units and associated facilities.
While it is known, based on conversations with City staff, that the lower of the two
density designations is considered the applicable set of designations for the PPA portion
of the site, an official determination of the appropriate density designations for the site
86123 10-8
10.Land Use
should be sought from the City prior to detailed design studies. Further, specific site
development guidelines regarding clustering of dwelling units, mix of housing types, and
use of attached units in clustering areas should be developed to reduce the alteration of
identified developable acreage.
EPA Buildout Potential
A wide range of dwelling units could be located in the EPA,pursuant to Plan policies. The
guiding policy in the EPA, mentioned earlier, is consideration of medium-density housing
on "flatter" land, and consideration of low-density housing on moderate slopes. For the
purposes of this analysis, it is assumed that "flatter"land means land with less than 20%
slopes, and"moderate"slopes means land that is between 20%to 30%slope. Applying the
major constraint criteria to the EPA portion of the project site (i.e., slopes over 30%,
riparian corridors and oak woodlands) results in approximately 33.6 acres of land that
could be used for residential development. Of this total, 16.6 acres have slopes less than
20%,and 17 acres have slopes of between 20%-30%.
Several interpretations of City policy render a wide range of development potential,
which, in turn, could be increased or decreased due to the incorporation of other criteria,
such as ridgeline maintenance or grading constraints. Assuming that identified acreage in
the EPA was incorporated into the PPA, for example, and designated with the same low-
density housing classifications as found on Sites 6 and 7 in the PPA portion of the project
site, the number of dwelling units that could be built on identified acreage could be the
following:
Acreage Plan,Figure 11 Plan,Page 82
33.6 34-104 units 30-202 units
1Density range of 1.0-3.1 units per gross acre. Upper limit of range based on mid-point of
upper limits of range for Sites 6 and 7.
2Density range of 0.9-6.0 units per gross acre.
Identification of approximately 16.6 acres of land as"flatter"land that can be considered
for multiple-family densities, and application of a range of housing densities, results in
the following:
•
86123 10-9
10. Land Use
Range with 1 Range with Multi-Family
AcreaEe Site 5 Density Plan Density2
16.6 100-133 units 101-232 units
1Density based on 6-8 units per gross acre,as stated on page 8 of the Plan.
2Density based on 6.1-14.0 units per gross acre,as shown in Figure 1 of the Plan.
If the 17 acres identified as areas of"moderate"slopes can be considered for low-density
residential development,the following range of potential development could result:
Range with 1 Range with Low-Density
Acreage Site 6 do 7 Densities Plan Densities2
17.0 17-53 units 15-102 units
1Densities based on midpoint of densities for Sites 6 and 7, as discussed on page 8 of the
General Plan.
•
2Densities based on low-density designations shown in Figure 1 of the Plan.
Combining buildout potential on both "flatter" and "moderate" sloped lands in the EPA
could result in the potential for as many as 116-334 units on 33.6 acres of land not having
the three major constraints identified earlier,resulting in a potential for a density of 3.5-
9.9 units per acre on identified acreage.
Summary
The range of development potential on the 32.0 acres of land in the PPA portion of the
project site not having any of the three major constraints identified earlier would be 35-
208 units, for a density of 1.1-6.5 units per gross acre. The range of development
potential on the 33.6 acres of land in the EPA portion of the project site not having the
same constraints would be 30-334 units,for a density of 0.9-9.9 units per gross acre.
Overall development potential on the 65.6 acres of land not having any of the three major
constraints identified earlier would be 65-542 units,for a density of 1.0-8.3 units per gross
acre. Again, this number could be increased or decreased when other on- and off-site
86123 10-10
10.Land Use
criteria are also considered. Further clarification of City policy is needed to narrow the
range of units that can be located on the site. It should be noted that the precise
identification of lands with less than major constraints,that can be developed in a manner
that minimizes alteration of the site, is perhaps more important than identification of a
number of permitted dwelling units. Once appropriate building envelopes are identified,
the identification of densities and building mix become more relevant and meaningful.
10.4 IMPACTS OF A POTENTIAL ROAD SYSTEM
Extension of urban services, including roads, onto the project site could result in impacts
on adjacent lands to the west, the majority of which are under Williamson Act agricultural
land contract. The purpose of this sub-section, therefore, is to examine the potential
impacts associated with an expanded road network in the EPA west of the project site.
The project site is considered part of the area's western hills, which were identified in a
1980 National Parks Service Study as an area of regional significance,9 suggesting that
local planning policies should reflect regional needs for open space and recreation
resources. Further, excluding parcels fronting on I-580, about 90% of the City's entire
EPA is under Williamson Act agricultural land contract. The State of California,pursuant
to Government Code Sections 51290-51293, clearly discourages public improvements on
agricultural preserve lands by establishing guidelines for State and County review of a
City's intent to approve a project requiring improvements on or across such lands.1° It is
clear,then,that development on or near agricultural preserves is more than a local issue.
Current Alameda County zoning regulations, which are still applicable in the EPA, permit
100 acre minimum lot sizes, and one dwelling unit per 100 acres. Assuming all lands in
the western EPA were zoned for agricultural activities, and assuming that the area
contained only 100 acre parcels, up to approximately 340 housing units could be
developed. This figure is, again, based on County regulations and must be considered a
theoretical maximum, however, as several parcels in the western EPA are larger than 100
acres.
The City's guiding policy regarding these lands is to maintain Williamson Act contract
lands as rangeland, provided that specific proposals for conversion to urban use consistent
with the General Plan may be considered not sooner than two years prior to contract
expiration. Another key policy appears at page 30 of the Plan, which states:
86123 10-11
10.Land Use
Prevent premature urbanization of agricultural lands.
The City's key implementing policy on conversion of agricultural land appears at page 15
of the General Plan,and is as follows:
Approval of development of agricultural land not under contract shall require findings
that the land is suitable for the intended use and will have adequate urban services
and that conversion to urban use will not have significant adverse effects on adjoining
lands remaining under contract.
It appears that the City's chief concern, then, with respect to the effects of an expanded
road system in the project vicinity, is that the timing of development not result in the
premature termination of viable agricultural operations on lands adjacent to the project
site. Review of Williamson Act lands, discussed above, shows that only one of the two
Nielsen parcels, in this instance the parcel immediately north of the project site, has not
been renewed, resulting in the potential conversion of that parcel to other uses after a
minimum of nine years. All other parcels have a minimum of ten years remaining before
contract termination, and a minimum of eight years before the City can review project
proposals.
Access to the site can be conceivably achieved from four locations: Silvergate Drive,
east of the site;Hansen Drive, south of the site; Canyon Circle,northeast of the site; and
via the Valley Christian Center, south of the site. Only Silvergate Drive would provide
direct access onto a major collector street; all other access points would require use of
minor collector streets, or, in the case of the Christian Center, construction of a new
road to connect to Dublin Boulevard. It is not known, however, whether the Silvergate
Drive access point could be capable of serving project-generated traffic at a level
consistent with maximum buildout potential of 65-542 units(see traffic analysis prepared
by TJKM,under separate cover,for more detail).
Site constraints (eg., slopes, soils, drainageways, tree cover, etc.) are such that
construction of more than a minimal minor collector street network could result in the
need for substantial grading and use of stringent erosion control methods. This would
appear to preclude the location of major collector or arterial streets on the project site to
serve the EPA should it be developed in the future. Location of a minor street network on
86123 10-12
10.Land Use
the site could act to induce growth on a portion of the Blaylock parcel to the west of the
project site, and could even be designed to serve that growth. While a street network
design for the site or the EPA has yet to be developed, and definitive analysis of impacts
is therefore premature, it appears that expansion of a road network onto the project site,
designed in a manner to minimize impacts, would have limited impacts on premature
development of adjacent agricultural lands.
10.5 POLICY REVIEW
This portion of the section will identify applicable General Plan policies, and provide a
discussion of the possible degree of project compliance with those policies.
RESIDENTIAL COMPATIBILITY
The General Plan, at pages 11-12, provides policies regarding residential compatibility in
both the PPA and EPA. In the PPA, the guiding policy is aimed at avoiding abrupt
transitions between single-family development and higher density development on
adjoining sites. Implementing policies include a requirement that all site plans respect
the privacy and scale of residential development nearby, and require a planned
development zoning process for all development proposals over 6.0 units per gross
residential acre. The project could, pursuant to the Plan,locate medium density housing
on the extreme northeast corner of the site, next to parcels planned for similar densities.
Further, this on-site higher density housing would be buffered from on-site low-density
housing by the existing creek flowing along the northern site boundary, as well as the
riparian vegetation in the creek corridor. Location of low-density housing in the southern
portion of the site would, if sensitively sited and screened, not be incompatible with
existing low-density housing along Hansen Drive,or the Valley Christian Center.
That portion of the project site in the EPA would be subject to different policies, again
precluding the assessment of the project as a unit. As stated earlier, residential proposals
(including residential support, if proposed) will be considered by the City on moderate
slopes, with multi-family densities considered on flatter land. Implementing policies
include the location/extent/density policy discussed above, as well as policies which
require a determination that provision of services in the EPA not pose a financial burden
on Dublin residents and businesses, site grading and means of access not disfigure
86123 10-13
10.Land Use
ridgelands, timing of development not result in premature terminations of adjacent
agricultural operations, and that the fiscal impact of new housing in the EPA not draw
upon and dilute the fiscal base of the remainder of the City.
The portion of the project site in the EPA would be subject to the policies outlined above.
That portion of the site would have to be considered as part of the entire project, rather
than a separate project, to accurately evaluate fiscal viability (see Section 10, Fiscal
Analysis,for further information). This portion of the site could be the location for up to
30-334 units in areas out of steep slopes, oak woodlands, and riparian corridors. Siting
these units could result in a decrease in the number of potential units due to the need to
minimize unsightly grading and accessways. As noted in the previous sub-section, the
potential would exist for the termination of agricultural activities on adjacent lands, but
it appears that impacts would be minimal due to steep slopes and access constraints
across the project site.
PUBLIC HEALTH AND SAFETY
dIC A policy often associated with enlightened planning practice is the formal recognition of
open space resource preservation as a means of promoting public health and safety. The
City's General Plan, at page 15, recognizes the health and safety value of open space in
policies calling for the preservation of oak woodlands, riparian vegetation, and natural
creeks as open spaces for resource value, as well as maintenance of slopes predominantly
over 30% as permanent open space. In conjunction with this orientation, City policy, as
stated in the Plan at page 35, regulates development in hill areas to minimize runoff by
preserving woodlands and riparian vegetation. Further, creek channels are to be retained
with right-of-ways for maintenance and for maximum water flow. Implementing policies
include required dedications of broad stream corridors, protection of riparian vegetation,
prohibition of woodlands removal and required preparation of drainage studies.
Approximately 55% of the project site, or about 81 acres, is either riparian corridor, oak
woodland, or sloped greater than 30%. Based on policy language, it is clear that the City's
intent is to retain existing site characteristics to the greatest extent possible. Any
proposal to alter oak woodland or riparian areas, or build on slopes over 30% would not
appear to be favorably reviewed by the City. Clarification of the extent of alteration of
these site characteristics while still adhering to the intent of General Plan policies will
86123 10-14
10.Land Use
payment. Once the number and mix of units is identified, calculations could be made to
determine land dedications and fees.
Somewhat related to recreation, a guiding policy of the General Plan, again on page 16,
restricts structures on hillsides that, "appear to project above major ridgelines."
Subdivision and site design review is to be used by the City to preserve or enhance the
ridgelines that form the skyline as viewed from freeways or major arterial streets. The
intent of the policies is to retain Dublin's appearance as a freestanding city ringed by open
hills. A portion of the project site can be seen from I-580 and several major arterials,and
thus would be subject to the provisions of this policy. It can be assumed, then, that the
area previously identified for potential development, based on slope, vegetation, and
riparian corridor constraints, may be further reduced to conform to the City's ridgeline
policy(see 5.,Visual Quality,for detailed discussion of potential ridgeline impacts).
SCENIC HIGHWAYS
I-680, I-580, San Ramon Road, and Dougherty Road were designated scenic routes by
Alameda County in 1966. These routes were those used by people travelling through the
Dublin area, and provided venues to gain visual impressions about the area. The City
incorporated, by reference, the previously designated scenic routes into the 1985 General
Plan. The key implementing policy is to conduct a design review of all projects within 500
feet of a scenic route and visible from it.
The project site is visible from I-580 but not 500 feet from it. Thus, the project would not
be subject to design review of all portions of the site pursuant to this policy. Regardless
of whether the site is more than 500 feet from the freeway, it can be seen from the
freeway. While no other guidelines are provided, consideration should be given to siting
and bulk of structures, building materials, planting materials, roadway cuts, and other
landscape alterations,particularly in the southwestern portion of the project site facing I-
580 (see Chapter 4,Visual Impacts,for discussion of potential visual impacts).
CITY AND REGIONAL HOUSING GOALS
The City of Dublin General Plan Housing Element, adopted in January 1985, is the leading
housing policy document in the City, and incorporates the Association of Bay Area
86123 10-16
10.Land Use
Governments (ABAG) regional fair share allocation for the City. While ABAG is
mandated by State law to identify and allocate regional housing needs, local governments
are not bound by law to attain housing allocation levels. ABAG has identified 1,956
dwelling units as the portion of overall regional need for the City, of which 665 units are
to be affordable to households with very low (less than 50% of median annual household
income)or low(50-80%of median income).
Dublin's 1983 housing stock was composed of approximately 4,040 single-family units in
1983, or 91% of the City's stock. Recent development has resulted in a shift away from
single-family homes, but the stock will still remain at least 75% single-family for the
foreseeable future.
Increasingly, households are having difficulty in purchasing housing, as housing prices
continue to increase relative to incomes. The target for units available to low and very
low income households will prove unrealistic unless federal subsidy programs for new
construction are revived and sites for construction of affordable housing are made
available. Housing prices in the Dublin area can be expected to increase rapidly as new
residents to the Tri-Valley area seek housing near to work.
In response to increasing needs for housing, the City's Housing Element contains, at page
25 of the General Plan,four goals that are intended to: promote housing of different size,
location and price to meet current and future housing needs; preserve existing housing
stock; ensure that housing will be served by adequate public services; and provide equal
housing opportunity and access for all. Key policies include the designation of suitable
sites for housing; the three areas identified for housing development on the project site
provide tangible evidence of this policy (see 11.3 above for detailed discussion of these
sites). Another key policy to provide below-market rate housing is City encouragement of
developers to cooperate with non-profit providers to develop below-market rate units.
Site 5, in the extreme northeast portion of the project site, is planned for medium density
housing, with a capacity of up to 16 units. Construction on this site would result in
increasing the supply of a small yet growing number of multi-family units in the City.
Further, consideration should be given to identifying Site 5 for below-market rate housing,
as it could be easily developed due to flatness and size, would be buffered from adjacent
86123 10-17
10. Land Use
lower density housing areas by riparian corridors and other barriers, and be compatible
with contiguous multi-family housing sites to the north and northeast. Consistent with
City policy, consideration should be given to developer cooperation with non-profit
housing providers to enhance the potential for construction of high quality below-market
rate housing. This housing could be for lower income households that are either engaged
in or retired from the workforce.
10.6 DEVELOPMENT OPPORTUNITIES AND CONSTRAINTS
Major constraints, which serve to limit development on the site, include steep slopes over
30%, riparian corridors, and oak woodlands, all of which are invariably identified in the
City's General Plan for protection, preservation, or retention. At no point in City policy
statements is there reference to removal or management of these resources, with the
singular exception of possible consideration of one oak tree as part of the project review
process. It should, therefore, be noted that at most 81 acres, or 55% of the project site,
is considered to have very low development potential. Further investigation is needed,
however, to clarify the City's precise interpretation of such seemingly inviolate policy
statement words as"prohibit,""preserve"and"protect." Given a literal interpretation of
these words should not, however, be construed as setting the upper limit of development
potential on the site, as reinterpretation of these words as well as other policies, most
notably those associated with geologic hazards, vegetation and wildlife, ridgeline
management, traffic and services, could serve to increase or decrease development
potential.
Major opportunities exist on the site to build housing to meet a portion of the housing
needs of new residents to Dublin, or current residents wishing to move into higher quality
housing. Further, an opportunity exists to provide below-market rate, medium density
housing consistent with identified housing needs that the City formally acknowledges as
difficult to attain. This housing could be located in the extreme northeastern corner of
the site, and could be designed to be compatible with adjacent land uses, and not be built
at a scale that might prove objectionable to residents in the area. This portion of the site
is one of the few readily developable areas in the western portion of the City with
appropriate zoning and other characteristics that could make below-market rate housing
feasible. This housing could be tailored to, for example, the needs of lower income
households working in the Dublin area.
•
86123 10-18
10. Land Use
10.7 DATA SOURCES
The following data sources were used in the preparation of this section. In addition,
persons were contacted for various reasons in the course of section preparation. The
names, titles, and affiliations of these individuals appear in the footnotes at the end of
this section.
Association of Bay Area Governments (ABAG), Housing Needs Determination, San
Francisco Bay Region,July 1983,p. 44.
, Projections'85,August 1985.
City of Dublin, General Plan, February 1985.
,Housing Element,Vol.2,Technical Supplement,January 1985.
, Zoning Ordinance, 1985.
, City Council Agenda Statement,August 11, 1986.
General Plan Draft EIR, February 1984.
, Responses to Comments on Supplement to Environmental Impact Report,
February 1985.
County of Alameda,General Plan.
, Zoning Ordinance.
David Gates and Associates, Hansen Hill Ranch Environmental Planning Study, 1986.
1Kevin Gaily, Senior Planner, City of Dublin Planning Department, telephone
communication, November 18, 1986.
2Darryl Gray, Associate Planner, County of Alameda Planning Department, telephone
conversation, November 13, 1986.
3John DeHorn, Consulting Engineer, Hansen Hill Development Corporation, discussion,
November 14, 1986.
4Calculations of various acreages on and off the site are derived from maps at various
scales and levels of accuracy. Therefore, all such calculations should be viewed as both
preliminary and approximate.
86123 10-19
10. Land Use
SCity of Dublin General Plan, February 1985, p. 10.
6Ibid., p. ii.
7A comparison of the Slope Analysis map at page 22 of the Hansen Hill Ranch
Environmental Planning Study, prepared by David Gates be Associates (project sponsor
consultant), with Figure 8 at page 32 of the City of Dublin General Plan reveals that
slopes over 30% comprise a greater percentage of the EPA portion of the project site
than shown in the Plan. The discrepancy may be due to the scale of analysis used in the
Gates analysis, which would facilitate more detailed analysis than that used in the Plan.
8Calculations prepared by EIP Associates.
9City of Dublin General Plan, February 1985, at p. 28.
•
10Jack Fergeson, Principal Planner, California Office of Planning and Research, telephone
communication, March 6, 1986.
86123 10-20
I
11 CONCLUSION
11.1 COMPOSITE CONSTRAINTS SUMMARY
The main concern in this section is to compile and review the significant physical and
biological characteristics of the site as an initial approach in contributing to the
formulation of development concepts.
The Summary Composite Constraints Map has been prepared by extracting from each of
the large-scale factor maps those environmental features that would preclude construction
or offer high constraints to construction. The composite map is thus simplified in terms
of the quantity of data shown, as indicated below:
CONSTRUCTION UNSUITABLE
Map Symbol Description
Ls Large Landslides
Ce Creek Erosion Zone
Rc Riparian Corridor
Sk Scenic Knoll
CONSTRUCTION CONSTRAINED
Map Symbol Description
SL Slopes More Than 30%
Ow Oak Woodland
Vp Visual Prominence
An examination of the map shows considerable overlap of the above features, particularly
around the lower slopes parallel to the creek. Although the map shows that most of the
site is covered by unsuitable or constrained construction, it must be stressed that within
86123 11-1
•
11. Conclusion
both categories there are exceptions and mitigable opportunities as expressed in the
individual chapters of this report. For example, the large landslide areas, though included
in the unsuitable rating, should be subject to further site engineering studies to determine
the depth and degree of activity of each slide mass. Moreover, both the vegetation and
visual sections offer caveats for the high constraints areas within these topics. Where
overlapping constraints occur, particularly within the Construction Constrained category,
are areas that would indicate that mitigation techniques would progress to higher levels,
and that impacts would likely be more severe. For example,oak woodland within areas of
greater than 30% slope would represent areas of potentially greater impact. Conversely,
development in areas not covered by map symbols are considered to be low to moderately
constrained, and would incur low orders of impact.
11.2 ANALYSIS OF PRELIMINARY SITE CONCEPTS
Two development concepts that have been considered by the applicant are labeled A-Hill
Orientation and B - Creek Orientation. The former concept shows the main access
collector street as extending along the long axis of the site, across the upper slopes near
the southern site boundary. Developable areas extend downslope from entry-ways off of
the main collector. Concept B - Creek Orientation indicates the main access route
parallels the creek with access points to residential areas upslope from the collector.
By overlaying the two concept diagrams on the Composite Constraints Map, some
generalizations can be made about their merits in terms of relative potential impacts:
HILL AREA ORIENTATION
o More potential for development to impinge on large slide areas requiring detailed
geotechnical studies to identify avoidance or slide stabilization mitigations.
o Roadways are less likely to cross oak-wood land/swale areas within tributary creek,
thus avoiding interception of wildlife migration routes. In addition, the main access
route avoids the riparian area altogether.
o More emphasis on development in high constraint visually prominent zones, requiring
detailed siting and building design mitigation to increase absorption capacity.
o Earth grading for roads may require detailed mitigation to avoid soil color contrasts
in visual prominence zone.
86123 11-2
11.Conclusion
o Main collector routes would increase access to adjacent properties to the west,
although this may be considered a potential growth-inducing feature.
CREEK ORIENTATION
o Main road alignment impinges on riparian corridor although an adjusted alignment
would establish a permanent buffer between development and the creek-side riparian
community.
c Main road crosses oak-woodland swales increasing impacts to migrating wildlife
through tributary creeks to the riparian zone.
o Development oriented downslope nearer the creek could take advantage of building
envelopes on flatter,high tree canopy locations within the oak woodland.
o Creek orientation may occur more development downslope and away from visually
prominent areas.
o Main road alignment suggests a more "self-contained" approach, reducing future
access to adjacent properties and decreasing growth-inducement potential.
11.3 RELEVANCE FOR DEVELOPMENT
Given the number and extensive coverage of potential constraints inherent in the Hansen
Ranch property, a traditional large-lot subdivision approach would not be appropriate here.
The uniform distribution of individual single-family structures carried out under uniform
low-density zoning ordinance regulations would incur serious impacts to visual, biotic and
geotechnical resources due to extensive building coveragegrading and landscaping
requirements.
To take maximum advantage of buildable sites and to focus design and siting mitigation
measures on areas delineated as "construction constrained" will require a Planned Unit
Development (PUD) orientation based on dwelling unit density transfer from open space
and highly constrained areas to areas of less potential impact. A development plan could
propose the clustering of higher net density common-wall structures at lower elevations
while providing more open space and larger parcels on the upper slope areas. Density
transfer would yield more protection and preservation of open space and could be
implemented through the deeding of development rights.
A high quality residential development on this property will be characterized by attention
86123 11-3
11. Conclusion
to exemplary building siting and design details. A mix of detached and attached
residential products that are sited to take advantage of existing vegetation screening,
while employing appropriate roof-pitches and earth-tone facades to blend into the
landscape would be the most positive approach. This scenario should also include reduced
grading techniques through the use of minimal roadway dimensions and cut slopes on
hillsides.
Project designers should review the following two documents for possible design and
mitigation principles. Both are considered appropriate sources of design guidelines
because they deal with local and similar landforms. The first document is Danville
Hillside/Ridgeline Development Standards by the City of Danville. This material offers
some useful and generic guidelines relating to ridgeline setbacks, cut and fill on hillsides,
roadway configurations, landscaping and architectural treatment. The second document
Oak woodland Preservation and Land Planning, Portola Valley Ranch, by Hardesty
Associates, March 1984 offers more detailed guidelines, particularly for viewshed and oak
woodland management.
•
86123 11-4
12 REPORT PREPARATION
EIP ASSOCIATE STAFF:
Linda Peirce Principal-in-Charge
Mark Trembley Project Manager
Yane Wordhoff Geotechnical Studies
Baseline
Ricardo Villasenor Vegetation and Wildlife
Jennifer Toth Visual Quality
Slope Analysis
Jeff Hornek Noise
Kristie Postel Archaeology
Douglas Svensson Public Services
Fiscal Analysis
Chuck Setchell Land Use
KEY CONTACTS:
City of Dublin Planning Department
Laurence L. Tong, Planning Director
Kevin J. Gailey, Senior Planner
Kathryn A. Wilson, Vice President, Venture Corporation
Sidney H. Cerates, P.E., Wilsey and Hann
Chris P. Kinzel, P.E., TJKM, Transportation Consultant
Other contacts listed under "Data Sources" in each report chapter.
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'Q y: �� Prominent Knoll Grassland
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-�Aa mapped by Nielson (1973). Guorled (7)
Stream or Gully js��','.Sojl.Sllppage, Soil Creep where quostlonnblo, approximately 1008tO
AW **Observed during field Investigation
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Coast'Llve :Oak%• Mature Trees
California' Bay` Forest, '
\ + ant Acor macrophyllum Uq Quercus agrlfolla
^' Chap' ; rai Blglosf,Maple Coast flue Oak
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r , \ '\ `'\•, \�• y Y •Nat1ve. Perennial., 'Callfornla, Buckeye.Valley Oak i
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j ✓% J`�` L.,Q'rin,ual Grassland O Callfornla Sycamore O Callfornla Bay
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