HomeMy WebLinkAbout8.1 EDublinCompStreamRstrPgrm
CITY CLERK
File # DGJ[3][Q]-[3J~
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AGENDA STATEMENT
CITY COUNCIL MEETING DATE: August 13,1996
SUBJECT:
EXHIBITS ATTACHED:
rCOMMENDATION:
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FINANCIAL STATEMENT:
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g:\east dub l\stream \ccsr\crc
Eastern Dublin Comprehensive Stream Restoration Program
(Report Prepared by Carol R. Cirelli, Senior Planner)~c.,
Exhibit A:
Eastern Dublin Comprehensive Stream Restoration
Program
Resolution Approving Exhibit A
Tassajara Creek Lower Reach Implementation Plan
for Ownership/Maintenance/Operation
Related Eastern Dublin Specific Plan Action
Program 6F and EIR Mitigation Measure 3.7/12
Eastern Dublin Comprehensive Stream Restoration
Program Summary
MacKay & Somps Comment Letter Dated July 15,
1996 and Staff Responses
Exhibit B:
Exhibit C:
Exhibit D:
Exhibit E:
Exhibit F:
1)
2)
3)
4)
5)
Hear staff presentation.
Take testimony from the public.
Question staff and the public.
Deliberate.
Adopt draft Resolution, Exhibit B, approving the Eastern Dublin
Comprehensive Stream Restoration Program, and the Tassajara
Creek Lower Reach Implementation Plan, Exhibit C; or give staff
direction and continue the matter.
The City has been initially covering the consultant contract costs for
this project. The City is in the process of establishing a method for
recovering any costs associated with implementing the Eastern
Dublin Specific Plan. These contract costs will be recovered
through the processing of future development projects within the
Eastern Dublin Specific Plan area.
COPIES TO: IN-HOUSE DISTRIBUTION
ITEM NO.
8.1
DESCRIPTION:
The Eastern Dublin General Plan Amendment/Specific Plan and companion EIR requires the City .
to prepare and adopt certain implementation plans and programs before Eastern Dublin development .
occurs. In addition to the Grazing Management Plan and Wildfire Management Plan, the City has
completed the Eastern Dublin Comprehensive Stream Restoration Program (Stream Restoration Program).
The City hired the consulting firm of Sycamore Associates to prepare the Stream Restoration
Program for the Eastern Dublin General Plan Amendment area. Sycamore Associates is highly
experienced in preparing stream restoration plans. Their project team, comprised of plant and animal
biologists, hydrologic engineers, civil engineers, and planners, demonstrated a very good understanding of
the Eastern Dublin General Plan Amendment/Specific Plan goals and action programs for preserving one
of the City's most significant hydrological, biological, aesthetic and recreational resource, Tassajara
Creek.
PLANNING COMMISSION
The Planning Commission discussed this item at the July 16, 1996, Planning Commission
meeting. After hearing public testimony and reviewing the comment letter from MacKay & Somps
(representatives of the Jennifer Lin Family) dated July 16, 1996 (Exhibit F), the Planning Commission
recommended City Council approval of the Stream Restoration Program, without any document changes.
Since that meeting, staff has prepared responses to their comments (see Exhibit F). Prior to the Planning
Commission meeting, staff had met with other Eastern Dublin property owners and affected resource
agencies that had comments, and all were satisfied with the City's responses to their comments, except for
MacKay & Somps.
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EASTERN DUBLIN COMPREHENSIVE STREAM RESTORATION PROGRAM
Introduction
The Eastern Dublin Specific Plan includes stream restoration policies for Tassajara Creek and its
tributaries that promote the enhancement of these streams' natural functions as drainage channels, habitat
areas, and wildlife corridors. The policies also promote the enhancement of the channels as aesthetic and
recreational resources for the proposed Eastern Dublin community.
Action Program 6F of the Eastern Dublin Specific Plan and Mitigation Measure 3.7/12.0 of the
Eastern Dublin General Plan Amendment/Specific Plan EIR requires the City to develop a comprehensive
stream corridor restoration program that includes a detailed set of criteria for grading, stabilization and
revegetation of the planning area stream channels, and guidelines for plant species, planting densities, and
long-term maintenance and responsibilities. The program is intended to facilitate project processing and
ensure a consistent standard for stream channel improvements throughout the planning area. The City
was required to develop this program while working cooperatively with the Alameda County Flood
Control and Water Conservation District, Zone 7 Water Agency (Zone 7), the California Department of
Fish and Game and the East Bay Regional Park District (EBRPD).
The draft Stream Restoration Program, Exhibit A, contains guidelines and criteria for hydrology
and water quality (reducing flood hazard, runoff water quality, soil and groundwater quality, channel
stability and erosivity, etc.), planning (channel cross sections and stream setbacks, trails and maintenance
roads, development interface, etc.), and resource protection, restoration and mitigation. The document
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also contains an implementation (long-term management) and regulatory compliance chapter. Exhibit E
is a summary of the Stream Restoration Program standards, guidelines and recommendations.
The consultants prepared the Stream Restoration Program through collaborative efforts with City
staff, Zone 7, EBRPD, County of Alameda Public Works, California Department ofFish and Game,
.landowner representatives, Natural Resource Conservation Service and the East Bay Municipal Utilities
District.
The Stream Restoration Program supports the Specific Plan policies of designing and performing
flood control maintenance practices to be responsive to public safety while preserving the unique riparian
communities. It addresses the protection and enhancement of wildlife habitat, flood control management,
public access (i.e., local and regional trails accommodating pedestrian, equestrian and bicyclists) and the
separation/buffering ofwil~life habitat from incompatible human activities.
The successful implementation of the Stream Restoration Program implementation will involve
the participation, review and approval of various governmental agencies. For example, EBRPD, Zone 7,
and the California Department of Fish and Game should review all development plans along the stream
corridors. Additionally, appropriate regulatory agencies should review these plans as part oftheir
agency's permitting process and the Stream Restoration Program strongly encourages early project design
review and involvement of these agencies (see the "Regulatory Compliance" section of the Stream
Restoration Program). The following sections summarize each agency's role.
City of Dublin's Role
The policies and guidelines of the Stream Restoration Program shall be enforced for all new
.rezone and tentative map applications for properties locate.d within the Eastern Dublin Specific Plan area.
The document presents suggested guidelines and criteria from which the City will base stream restoration,
hydrologic and site planning/development setback requirements and conditions of approval for rezones
and tentative maps.
For proposed development projects that are adjacent to Tassajara Creek or the creek's tributaries,
the City will require as conditions ofPD Rezone and Tentative Map approval, flood control, trail, road,
revegetation, restoration, enhancement and landscaping improvements in compliance with the Stream
Restoration Program. Appendix B of the Stream Restoration Program outlines the PD Rezone, Tentative
Map and Final Map application submittal requirements for restoring the stream corridor.
The Stream Restoration Program emphasizes that the stream portions of the Specific Plan area
should not be fragmented from adjacent development during the planning and review process. The
proposed creek hydrologic and revegetation improvement plans will be reviewed and approved with the
Final Map. Flood control improvements must be completed prior to issuance of building permits. Creek
revegetation and landscaping improvements should be made concurrently with flood control
improvements. This reinforces the state and federal regulatory requirements. If flood control
improvements are not necessary for a particular project, the City will still require that revegetation
improvements be implemented shortly after projects are developed.
The City's main objective is to apply these criteria and guidelines as the document recommends.
.However, depending on the results of the hydrologic and biological studies, certain guidelines and
standards may warrant some modifications. The City may apply some flexibility implementing these
guidelines and allow some guideline modifications only if these changes meet the intent of the Specific
Plan goals, policies and action programs, and Stream Restoration Program criteria and guidelines.
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The Stream Restoration Program acknowledges the potential for interrupting, or relocating the
trails, creek crossings and maintenance road extensions due to private property, topographical or other site
constraints. This interruption can occur as long as the trail/maintenance ingress and egress points are
provided at the points of interruption. For example, one land owner was concerned that the regional trail
extending along the rear portion of his property would impact his residential privacy. In this situation, the.
City would not extend the trail and maintenance roads along the rear of his property, or across any other
properties that would result in property site impacts, condemnation and/or structure removal. However,
this land owner would be required to comply with the Stream Restoration Program once he applies for
rezone and tentative map approvals consistent with the Eastern Dublin Specific Plan.
Zone Ts Role
Zone Ts flood control mandate is that Tassajara Creek contain 100 year flood flows. Zone 7 will
evaluate flood conveyance on behalf of the City and evaluate it for reaches which Zone 7 may own.
Based on detailed hydrologic studies for each development proposal, Zone 7 will determine whether flood
conveyance is adequate for the channel.
Zone 7 will accept ownership and maintenance responsibility for flood control purposes for
channels that have been improved to Zone 7 standards. Zone 7 has Special Drainage Area funding to take
ownership of the lower creek reach (1-580 Fwy. to Gleason Drive.) This special funding area may be
extended to cover a larger area along Tassajara Creek. It is possible that Zone 7 may acquire and maintain
other portions ofthe creek from Gleason Drive to the Contra Costa County line. However, Zone 7
reviewed the site conditions of the upper reach (from the EBRPD staging area to the Contra Costa County
line) and concluded that the severely eroded steep banks and other site conditions preclude their
ownership. Zone 7 may more than likely own the lower and middle reaches.
EBRPD's Role
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The Specific Plan requires the provision of a north-south trail along Tassajara Creek, and trails
along other stream corridors within the Eastern Dublin project area. The Specific Plan intended that the
required trail along Tassajara Creek become part of the EBRPD's regional trail network. The Stream
Restoration Program includes guidelines and development standards for one regional trail and one
optional local trail.
The EBRPD is interested in accepting a 30 foot easement for a regional trail along one side of
Tassajara Creek. The EBRPD would maintain this trail to its standards. The maintenance of this regional
trail could be funded through the EBRPD's two-county landscaping and lighting assessment district for
regional trail maintenance.
The EBRPD also expressed a willingness to explore a cooperative agreement with the City for
ownership, maintenance and operation of the open space within the Tassajara Creek corridor, excluding
the Creek itself, which should be the responsibility of Zone 7. They may be interested in owning and
maintaining not only the 30 foot trail easement, but the flood plain terrace area between the creek and the
30 foot easement. The EBRPD has certain requirements for assuming such responsibilities.
Regulatory Compliance
All Eastern Dublin Specific Plan development applicants need to comply with federal, state and
local environmental regulations. Applicants should demonstrate consultation with regulatory agencies
and compliance with environmental permits.
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Impacts to wetlands may require federal, state and/or local permits or agreements. Prior to the
issuance of grading permits that may impact potential onsite wetlands, permits/agreements may be
required from the following regulatory agencies:
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U.S. Army Corps of Engineers Clean Water Act Permit
California Department ofFish and Game Consultation/Agreement
State Water Quality Control Board Certification or Waiver
Tassajara Creek Lower Reach Implementation Plan for Ownership/Maintenance/Operation
The agencies responsible for owning and maintaining certain sections of the Tassajara Creek
corridor, between the I-580 Freeway and Gleason Drive, are depicted on pages 7 and 8 of the staff report.
Staff has met with the various agencies, including Alameda County (Lower Reach property owner), that
will have some form of maintenance, ownership and operation responsibilities for Tassajara Creek. All
agencies, including Alameda County, concur with the implementation plan, Exhibit C.
The City will be responsible for maintaining the local trail/maintenance road, 30' structure setback
and the optional trail landscaping on the west side of the creek and the optional landscaping on the east
side of the creek, between I-580 and Gleason Drive. The City will also be responsible for maintaining the
optional landscaping within the stream corridor, between the I-580 Freeway and Dublin Boulevard.
Zone 7 is interested in owning the whole creek corridor, between I-580 and Gleason Drive, which
includes the 30' minimum structure setbacks on both sides of the creek. They will maintain the creek
corridor for flood control and water conservation purposes only, and will maintain the maintenance roads
between the I-580 Freeway and Dublin Boulevard.
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At this time, EBRPD concurs with maintaining and operating the regional trail/maintenance road
and the 30' structure setback on the east side of the creek, between I-580 and Gleason Road. The
EBRPD's possible ownership, maintenance and operation responsibilities for the middle and upper
reaches of the creek will be determined at some future date.
Creek Ownership and Management Responsibilities for the Middle and Upper Reaches
The Stream Restoration Program recommends that a public agency should consistently own all 3
reaches within the stream open space corridor. Management of the middle and upper reaches may be the
joint responsibility of the EBRPD for maintenance and management of the regional trail; Zone 7 for
maintenance of the flood plain terrace and creek channel in specified reaches; and the City of Dublin for
the local trail and areas not maintained by Zone 7 or the EBRPD. The City is still in the process of
determining all creek ownership and management responsibilities for the middle and upper reaches.
Applicabilitv of Stream Restoration Program
Chapter 6 of the Stream Restoration Program includes resource protection, restoration and
mitigation guidelines for plants and wildlife. This is a very comprehensive chapter outlining methods and
guidelines for plant and wildlife habitat enhancement and restoration that project applicants can utilize
while preparing a creek restoration plan.
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Restoration will be required for all portions of the creek, regardless of channel modifications for
flood control purposes. The only exception would be the reaches of Tassajara Creek where existing and
native vegetation is abundant and diverse. In these areas, little to no planting is anticipated. However, in
this situation, the City will probably require some native vegetation enhancement, consistent with the
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Specific Plan Policy 6-11 that requires all stream corridors within the Eastern Dublin area to be
revegetated with native plant species to enhance their natural appearance and improve habitat values.
The revegetation guidelines shall especially apply where creek channel grading modifications
create large bare soil areas or remove large stands of vegetation. Where major grading and modifications .
are proposed to accommodate flood control and access along Tassajara Creek between Gleason Road and
1-580 Freeway, restoration plantings shall be required to provide stabilization and wildlife habitat, subject
to the California Department ofFish and Game review and approval.
In summary, for the lower reach of Tassajara Creek, restoration plantings will be required and the
City will be applying the Stream Restoration Program guidelines and criteria. For the middle reach, the
City will determine the level of plant restoration and hydrological improvements required. Optional
landscape (non-restoration) plantings could be permitted within the floodplain terrace/l 00' minimum
wildlife setback, and outside the 100' minimum wildlife setback. However, this landscaping will not
count towards any creek restoration or enhancement requirements. Due to potentially high establishment
and maintenance costs, such landscape improvements will only be allowed with City Council's approval.
For the upper reach, the City will determine the level of the Stream Restoration Program's applicability
after reviewing the detailed hydrological studies and the applicant's restoration plan submittal.
Landowner/Public Agency Comments
The draft Stream Restoration Program incorporates changes reflective of applicable land owner
and public agency comments received during the public review period.
CONCLUSION
Staff recommends that the City Council approve the Eastern Dublin Comprehensive Stream
Restoration Program, as specified in the Draft Resolution, Exhibit B. The document satisfies the
requirements of the Eastern Dublin General Plan Amendment/Specific Plan and EIR.
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T ASSAJARA CREEK LOWER REACH IMPLEMENTATION PLAN
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I Optional landscape plan lings I Required 1 Optionallandsc:lpe plantil1gs 1
~;;~;~~!1 s:~I~~~kO ~::d con fro' Cl'nnnel'forn~j#"iin'I-::c~:'rOl~nn:~...'-~:~I~~k:.~~O~;';~:~~
1(20' min) (30' minn (0100) ~ (0100) (30' min) (20' minl
@ @ 'o:X~~'",;!nk ~ @ @
f' 1 Exca"ate for flood
Existing gradD; (,Control cha:e~_ ' /
~!7/77</~~1 ~~~'/ ~~. ~
'/~///." / / / '/ /. - - - - - - - -:-~ '/ /. ~ ~ I )
, " // ~ y ~ I ~ " / ~ /1.,/1::-
(Mnlnlonanco rood ~~//~rAp. ~a;;"enonce road
C;;:andering
low flow
channel
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1
Wildlife setback*
(100' min.)
{- -{
Wildlife setback.
(100' min.)
stream Corridor
width varies
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TYPICAL CROSS SECTION
LOWER REACH
SUBREACH 1 - 15BO TO DUBLIN
-Measured from existing tep of b:mk
NTS
Thssajara Creek
Fig,3a Ownership Flood Control Maintenance Establishment Maintenance Establishment Ultimate
Maintenance & Operation of Required of Required of Optional Maintenance
Restoration Restorationl Landscape of Optional
Plantings Optional Plantings Landscape
Landscape Plantings
Plantings (:I:
3 - 5 years)
A Zone 7 Zone 7 Zone 7 N/A N/A County City - LLD
B Zone 7 Zone 7 Zone 7 N/A County County N/A
C Zone 7 Zone 7 Zone 7 County County N/A N/A
0 Zone 7 Zone 7 Zone 7 N/A County County N/A
E Zone 7 Zone 7 Zone 7 N/A N/A COllntv Citv - I I n
T ASSAJARA CREEK LOWER REACH IMPLEMENTATION PLAN
I Requffed I
lre<lornllon Plnnflng'T
Flood plain terrace . @ .1,
Optional landscape planli,,-gs tl
structure
setback
Flood plain terrace I (3D' min)
Trail/roa
right-of-way
(j)
Optional landscape plantings
Excavate for i Top of bank ~
flood plain terracfJ .
as reqUlred~ Excavate (or flood. plam
15 I I );terrace as reqUIred
. year eve; ,
,//~:: //7);7 /]V :arLl~~' . ,1,/ - - - - ~\t~ ." 1/ //X/7 /7 p- ~ .)
Existing grade..-/ __pl::- \ R~glonal tra,I/~
-II mamtenance road
Local trail/ see (lg. 9
maIntenance road
see fig. 10 Existing grade
structure
setback
(30' min) I
Trail/roa
right-of-wa
@
00
1
@
@
Wildlife setback"
(100' min.)
Wildlife setba.~~~_'____'r_
(100' min.) I,
._-,.r-
-(- -{
stream Corridor
width varies
A Zone 7 Zone 7 City - LLD
B Zone 7 Zone 7 Zone 7
C Zone 7 Zone 7 Zone 7
. 0 Zone 7 Zone 7 Zone 7
E Zone 7 Zone 7 EBRPD
Fig.3b
Ownership
-Measured from existing lop of bank
TYPICAl. CROSS SECTION
l.OWER REACH
SUBREACH 2 - DUBLIN TO GLEASON
NTS
Thssajara Creek
Flood Control
Maintenance
Establishment Maintenance Establishment Ultimate
of Required of Required of Optional Maintenance
Restoration Restorationl Landscape of Optional
Plantings Optional Plantings Landscape
Landscape Plantings
Plantings (t
3 - 5 years)
N/A County City - LLD
County County N/A
County N/A N/A
County County N/A
N/A EBRPD EBRPD
Maintenance
& Operation
. EASTERN DUBLIN COMPREHENSIVE STREAM
RESTORATION PROGRAM
SYCAMORE ASSOCIATES
BALANCE HYDRO LOGICS
dk ASSOCIATES
JUNE 1996
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TABLE OF CONTENTS
1.0 INTRODUCTION........ ................... ................. ....................... ....... .............. ..... ........ .......... 1
2.0 RESTORATION GOALS...................... ........... ..... ............. .......... ................... ......... ........ ..... 3
3.0 OPPORTUNITIES AND CONSTRAINTS OF THE SPECIFIC PLAN AREA
3.1 Hydrology, Hydraulics and Water Quality ................................................................. 10
3.1.1 Flood Hazard .......................................................................................... 10
3.1.2 Runoff Water Quality .............................................................................. 11
3.1.3 Channel Stability and Erosivity, Setbacks................................................... 11
3.1.4 Reclaimed Water .................................................................................... 11
3.2 Planning.................. ............. ....... ........... .......... ... ... ................................... .......... 11
3.2.1 Proposed Land Uses................................................................................ 11
3.2.2 Agency Requirements ...................... ......... ... ......... ... ..... ..... ..... ........ ........ 12
3.3 Resource Protection, Restoration and Mitigation ...................................................... 14
3.3.1 Existing Biotic Resources ....... ......... .................. ........ ............ ................... 14
3.3.2 Resource Protection, Restoration and Mitigation ......................................... 15
3.3.3 Biological Corridors ........ ...... .............. .... .... ..... ..... ........ .......... ....... .......... 15
3.3.4 Invasive Exotic Plants .... .... ........... .......... ........ ........... ............ ... ........... .... 16
3.3.5 Specimen Trees.................. ......... ...... .... ..................... .......... .... .............. 16
3.3.6 Soils..................................................................................................... 17
3.3.7 Project Scheduling and Phasing ................................................................ 17
3.4 Three Reaches .. ..................................... .... .............. ...... ................. ....... ...... ........ 17
3.4.1 Lower Reach.. ..:.. ................................... ............. .......... ..... .................... 17
3.4.2 Middle Reach.............. ....... ........ .... ............. ................... ......... ....... ........ 19
3.4.3 Upper Reach ....... ... .... ........ .................. ............ ..... ........ ......... ... .............. 20
4.0 RESTORATION GUIDELINES: HYDROLOGY, HYDRAULICS AND WATER QUALITY
4.1 Introduction ...:.... ...... ............... ....... .............. .... ............ ........... .... ...... .... .......... .... 21
4.2 Reducing Flood Hazard.... ............... ..... ..... .............. ...... .............. ..... .... ..... ......... .... 21
4.3 Runoff Water Quality............ ....... .......... ............. ... ........... ....... ......... ............. ....... 23
4.4 Soil and Groundwater Quality............ ........ .... .......... .... ............. ..... ....... ... .... ........... 24
4.5 Erosion Reduction .......... ........ ........ ....... ............ .\. ........ ............... ........... :... ........... 24
4.6 Channel Stability and Erosivity, Setbacks ................................................................ 24
4.7 Reclaimed Water ..... ... .......... .... ......... ..... .... ........ ............ ...... ......... .............. ...... ... 28
4.8 Hydrology and Hydraulics Reference Bibliography..................................................... 29
5.0 RESTORATION GUIDELINES: PLANNING
5.1 Channel Cross Section and Stream Setbacks ........................................................... 33
5.2 Trails and Maintenance Roads ............ ........... .......... .... .... .... .......... ..... .................... 39
5.2.1 Regional Trail/Maintenance Road Standard................................................. 40
5.2.2 Local Trail/Maintenance Road Standard.................................. ..... ...............48
5.2.3 Gravel Maintenance Road Standard .................. ..... ............. .......................49
5.2.4 Trail Standards by Reach of Tassajara Creek...............................................49
5.2.5 Staging Areas and Trail Heads for Hiking and Equestrian Trails ...................... 50
5.3 Stream Crossings ...........:... ........................... ........ ........ ... ........... ....... ............ ...... 51
5.4 Development Corridor Interface ................. .......... ............... ..... ........................... .....52
5.5 Channel Modifications and Stabilization ...... ........... ....... ....... ............... ...... ...... ........ 57
6.0 RESTORATION GUIDELINES: RESOURCE PROTECTION, RESTORATION AND MITIGATION
6.1 Creek Setbacks and Buffer Configuration................................................................. 59
6.2 Tributaries to Tassajara Creek ........ ....................... ........ ......... .......... .... ......... .... ..... 60
6.3 Cre.ek Channel and Bank Modifications .................................................................... 60
6.4 Engineering and Bioengineering Techniques ............................................................. 61
6.5 Protection of Specimen Trees............. ................. ...... ..... .... .......... ....... ....... ............ 68
6.6 Protection of Sensitive Resources ........................................................................... 69
6.7 Identify Opportunities to Integrate Mitigation into the Creek Restoration Program ......... 70
6.8 Project Scheduling, Construction Restrictions and Coordination Requirements .............. 72
6.9 Lighting in Habitat Areas. .... .......:....... ... ..... ...... .... .... ........ ........ .............. .......... ..... 73
6.10 Treatment of Transitions to Off-site Open Space .................................................... 75
6.11 Landscaping of Trails and Adjacent Development ................................................... 75
6.12 Interpretation ... ........... ... ...... ........ ........ .......... ......... ........ ........ .......... .............. ... 76
6.13 Installation of Bird Nest Boxes ......... .......... ......... ......... ........ .............. ................... 76
6.14 Restoration Treatment of the Three Reaches.......................................................... 80
6.15 Exotics Plant Eradication...................................................................................... 82
6.16 Debris Removal .................................................................................................. 84
6.17 Soils Testing and Treatment....... ... ......... ...... ........................ ............... ......... ........ 84
6.18 Restoration Plant Palette...................................................................................... 86
6.19 Groundwater Testing and Planting Zones............................................................... 86
6.20 Planting Under Oaks.. .... ,..... .., ......... ......... ....... ..... ..... ....... ....... ..... ..... ....... ........... 88
6.21 Container Sizes and Plant Spacing ........................................................................ 90
6.22 Plant and Seed Procurement ................................................................................ 92
6.23 Mycorrhizal Fungi ................ ........................................................ ....................... 92
6.24 Storage and Handling of Seed and Plants............................................................... 93
6.25 Commercial Sources of Plant and Seed Materials.................................................... 93
6.26 Genetics Conservation Guidelines........... ............... ..... ...... ....................... ........ ..... 95
6.27 Techniques of Local Cutting Collections ................................................................ 96
6.28 Techniques of Local Seed Collections.................................................................. 110
6.29 Container Planting Techniques................. ........................................................... 110
6.30 Seeding Techniques ... .... ............ ....... ...... .... ........... ...... ........ ..... .... .... ... .... .........- 112
6.31 Transplanting Techniques .........:........................................................................ 113
6.32 Areas Expected to Naturally Revegetate ..............................,................................ 114
6.33 Plant Protection................ ................................................................................ 114
6.34 Temporary Irrigation System .............................................................................. 115
6.35 Salvage and Placement of Woody Debris ............................................................. 116
6.36 Horticultural Monitoring and Establishment Maintenance........................................ 116
6.37 Habitat Monitoring............................................................................................. 120
6.38 Wildlife Surveys................ ................................................................................. 121
6.39 Long-Term Management of Habitat...................................................................... 121
7.0 IMPLEMENTATION
7.1 Implementation and Management....... ..... ........... .... ..... .... ...... ..... .... ........ .............. 123
7.2 Regulatory Compliance.......... ............. ........ .............. ...... ........... ......... ............... ... 124
7.2.1 Army Corps of Engineers............ ..... .......... ....... .............. ..... .................. 124
7.2.2 California Department of Fish and Game.................................................. 126
7.2.3 State Historic Preservation Office ........................................................... 127
.7 .2.4 Stat~ Water Quality Control Board Certification ........................................ 127
7.2.5 Regional Water Quality Control Board...................................................... 128
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Table 1.
Table 2.
Table 3.
Table 4.
Table 5.
Table 6.
Figure 1 .
Figure 2.
Figure 3a.
Figure 3b.
Figure 4.
Figure 5.
Figure 6.
Figure 7.
Figure 8.
Figure 9.
Figure 10.
Figure 11 .
Figure 12.
Figure 13.
Figure 14.
Figure 15.
Figure 16.
Figure 1 7.
Figure 1 8.
Figure 19.
Figure 20.
Figure 21 .
Figure 22.
Figure 23.
Figure 24.
TABLES AND FIGURES
Recommended Plant Palette .... ........... ............... ..................... ... ...... ...... ............. 98-101
Growth Habits of Plant Species Recommended for Restoration.............................. 102-104
Recommended Species For Planting Under Oaks ....................................................... 105
Plant Availability and Schedule of Local Collections .......................................... ....1 06- 1 08
Recommended Prohibited Species ...... ............................................. ............ ...... ....... 109
Monitoring Schedule ......... ....... ............. ....................... ........................................ ... 122
Hypothetical Example of Setbacks ..................................... ........ ....................... .......... 27
Corridor Plan Area.......... ........................................................................................... 34
Typical Cross Section Lower Reach Subreach 1 1-580 to Dublin...................................... 35
Typical Cross Section Lower Reach Subreach 2 Dublin to Gleason.................................. 36
Typical Cross Section Middle Reach .............. ........ ................................................... .. .37
Typical Cross Section Upper Reach ............................................................................ 38
Plan View Concept Lower Reach .............................'................................................... 42
Plan View Concept Middle Reach ........................ ....... ...... ........... ..... ............. ...... ........ 43
Plan View Concept Upper Reach............ ............ ............... ........ ............ ............. ......... 44
Regional Trail I Maintenance Road............. .......... ................ ...... ...... .................... ........ 45
Local Trail I Maintenance Road ................................................................................... 46
Local Trail ... ................................... ............................. ............................................. 47
Residential Development Interface............................................................................... 54
Commercial Development Interface with Stream Corridor............................................... 55
Residential Development Interface with Stream Corridor ............................................... 56
Grading Back Slope and Planting ..... ..... ........... ..... ............. .................................... ..... 63
Toe of Slope Retrofitted with Rip-Rap and Planted ........................................................ 64
Rip-Rap with Planting Pocket........ ................................... ........................ ................... 65
Terraced Banks fnr Slope Stabilization ..... ...... ......... .............................................. ...... 66
Terraced Banks for Slope Stabilization ..... ......................... ... ....... ......... ....................... 67
Ughting .. ....... .... ....... ... ..;......... ........ .......... ............ ......... ........... .... .......................... 74
Sample Nest Boxes .. ........................... ......... ............... .................... ...... ............ ....... 78
Sample Nest Box Building Plan ............................. .......... ................ ............................ 79
Planting Zones .............. ... ................... ............ .................. ....................... ................ 89
Planting Detail....................................................... ................................................... 91
APPENDIX
Appendix A Revegetation Schedule
Appendix B Special Submittal Requirements
EASTERN DUBLIN COMPREHENSIVE STREAM
RESTORATION PROGRAM
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1.0 INTRODUCTION
This Comprehensive Stream Restoration Program has been prepared as required by the Eastern
Dublin Specific Plan. Restoration goals contained herein are based on policies and programs in
the Specific Plan document and on hydrological, biological, and planning principles.
Opportunities and constraints analyzed in this document are based on considerable research,
meetings with various agencies and consultations with interested parties. The restoration
guidelines are organized by hydrology, planning and biological issues. Implementation,
regulatory compliance and long-term management issues are also discussed.
The City of Dublin shall enforce the Eastern Dublin Comprehensive Stream Restoration Program
policies and guidelines for all Eastern Dublin rezoning and tentative map applications. Appendix
B of this document outlines the rezone and tentative map application submittal requirements for
stream corridor restoration. Through these submittal requirements, the applicants shall
demonstrate compliance with the stream restoration guidelines.
As part of rezoning and tentative map application processing, all applicants will be required to
prepare detailed hydrologic studies and restoration plans in compliance with the Comprehensive .
Stream Restoration Program. These plans will then be reviewed and approved with the final
map. "
The City's main objective is to apply the Program's standards and guidelines as recommended.
However, depending on the results of the hydrologic and biological studies, certain guidelines
and st/:illdards may wEJITant some modifications. In other words, the City may apply some
flexibility implementing the Program and allow some guideline modifications .Qll}x if these
changes meet the intent of the -Specific Plan goals, policies and action programs, and the
Comprehensive Stream Restoration Program guidelines and standards.
Issues discussed in this report include channel cross sections, flood control capacity and
maintenance requirements, regional and local trails in conjunction with maintenance roads,
habitat protection and restoration, landscaping, recreation, long-term maintenance and
management and the interface between the Tassajara Creek corridor and adjacent development.
The authors collaborated with the City of Dublin, East Bay Regional Park District, County of
Alameda Public Works, Zone 7 of the Alameda County Flood Control and Water Conservation
District (Zone 7), California Department ofFish and Game, landowner representatives, Natural
Resources Conservation Service and East Bay Municipal Utilities District.
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The goals of the stream restoration program range from protection and enhancement of wildlife
habitat to flood control management and public access. Restoration goals address the inherent
limitations of the creek and flood control channel, and focus on separating and buffering wildlife
habitat from incompatible human activities. Regional v,riJdlife, including birds, reptiles, amphibians,
mammals, and aquatic species use Tassajara Creek and its tributaries for nesting, food, cover,
breeding and dispersal of young. Wildlife will continue to use Tassajara Creek and its tributaries if
these open space connections are maintained. Restoration efforts focus on wildlife enhancement,
while locating development and trails away from habitat areas. The stream corridor cross section
required for flood conveyance will provide an adequate setback from the Tassajara Creek channel,
and a concentration of wildlife usage is anticipated in this area. To further reduce impacts to
available habitat, trails can be combined with maintenance access roads. While limited in the extent
of habitat available for wildlife, the urban environment does provide opportunities to improve the
stream corridor and link the natural environment with adjacent development through trails.
The historically dynamic nature of the riparian system has been altered and affected by human
influences. Previously, rivers and creeks meandered, animals migrated great distances, and
vegetation mosaics changed continually. Riparian corridors depend upon periodic flooding, erosion
and sedimentation to create the conditions necessary for natural regeneration. The relatively short
lived riparian species require scour to eliminate senescent vegetation and regenerate. Exposed to
periodic flooding disturbance, many species have evolved breeding systems dependent upon floods
for clearing old vegetation, making new sites available for establishment, amending the soil with
nutrient-rich silt and organic matter, and facilitating seed dispersal. Protection and enhancement of
the stream corridor will be accomplished by preserving the natural processes of the Tassajara Creek
system. The biologist Douglas H. Chadwick eloquently described the importance of design in
preserving the full range of evolutionary processes when he wrote:
"We cannot tuck species away in little preserves as if we were storing pieces in a museum,
then come back a century later and expect to find them all still there. The essence of life is
change. Organisms are constantly growing, interacting, adapting, evolving. Their
numbers and distribution across the landscape fluctuate in cycles linked to climatic patterns
and to other, less understood rhythms. They are defined as much by their place in food
webs and nutrient flows as by their own physical traits or any current geographic location.
Many alter their range and behavior under different conditions. Some assume entirely new
behaviors through learning. In short, an eCOSYSTem is not a collection of planTS and
animals. It is a seamless swirl 0.[ communities and processes. ff you don't save the
processes. you won't save the parts. So if you're going to create a preserve, you had better
make it a big one. "
\Vith a clear vision of its restoration goals, the City of Dublin can embark upon the restoration
planning process. Use of this restoration program will ensure the protection of the natural processes
ofTassajara Creek.
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RESTORATION GOALS
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2.0 RESTORATION PROGRAM GOALS
The project restoration goals described below are based on the policies and programs of the Eastern
Dublin Specific Plan, and biological, planning and hydrologic principles. Policies and programs
from the Specific Plan that relate to these goals are noted below in italics.
Program--6F: The City should work with Zone 7 and the
Department of Fish and Game to develop a comprehensive stream
corridor restoration program that identifies a detailed set of
criteria for grading, stabilization and revegetation of planning
area stream channels. The program would provide guidelines for
plant species, planting densities, and long-term maintenance
requirements and responsibilities. Such a program will facilitate
development approval and insure a consistent standard for stream
channel improvement throughout the planning area. The program
should identify the procedures to be followed by applicants for
development, permits to be obtained, and improvement and
revegetation practices to be implemented. The program should be
reviewed by East Bay Regional Parks District.
Stream Setbacks
Setbacks from the Tassajara Creek channel and the flood plain terrace for structures and trail
construction will be established, providing for the protection and enhancement of biological
resources, flood control and channel migration. These setbacks will be consistent with the
regulatory requirements of the appropriate flood control and regulatory agencies.
Program 6G: The City should require dedication of land and
improvements (i.e., trails, revegetation, etc.) along both sides of
stream corridors as a condition of subdivision approval. The width
of dedicated corridors will be established in consultation with the
regulatory authority since these may vary with specific sites.
Development Interface
Development adjacent to the stream corridor, including the Tassajara Creek channel and the
flood plain terrace, should be sited and designed to provide for: protection of riparian habitat and
wildlife movement in Tassajara Creek and its major tributaries; regional flood control and
maintenance access; regiQnal trail connections accessing schools, parks, neighborhoods, parking
and commercial centers; and trail siting and landscaping consistent with trail.user safety and
police patrols. Conscientious development should incorporate: an emphasis on single loaded
streets or cul-de-sac streets that open to the Tassajara Creek corridor; frequent access to trails
from adjacent development to encourage trail use as a local pedestrian transit corridor;
combining trails \.\Iith maintenance access roads; placing stream crossings where existing
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crossings occur or where new crossings would not result in adverse impacts to sensitive
biological resources; and compatible landscaping treatments oftrails and adjacent development. .
Treatment of adjacent development and trails should be designed to provide for public safety,
especially in the middle and upper reaches ofTassajara Creek and its tributaries where steep
banks present a potential public safety hazard.
Policy 6--1-4: Enhance public enjoyment and visibility of stream
corridors by avoiding, or minimizing, development that backs
directly onto the stream corridor, and ensure safe public access to
stream corridors by providingfrequent access points within each
development area.
Trail Access and Connections
Trails within the stream corridor should be sited and constructed to minimize impacts to riparian
vegetation and wildlife in the Tassajara Creek channel, and should be integrated with existing
and anticipated creek crossings. Trails should be located outside of anticipated flood and
sediment deposition areas if feasible, to minimize on-going maintenance. Trail siting,
landscaping, lighting, and interpretative signing in the stream corridor should be appropriately
designed to minimize impacts to native wildlife, and should provide view corridors as well as a
transition to adjacent development and other trails.
Policy 4-23: Require all employment-related development to
provide convenient and attractive pedestrian, bicycle, and transit-
related facilities to encourage alternate modes of commuting to
and from work
Policy 5-15: Provide a north-south trail along Tassajara Creek,
and trails along other stream corridors as shown on the
Pedestrian and Bicycle System map.
Policy 6-3: Provide convenient access from developed areas to
designated open space areas and trails. Emphasize pedestrian
connections between developed and natural areas.
Policy 6-13: Establish a stream corridor system which provides
multi-purpose open space corridors capable of accommodating
wildlife and pedestrian circulation. In order to facilitate the use of
these corridors by both humans and wildlife, human activities
(e.g., trails) should be limited to one side of the stream.
Maintenance Access
Maintenance roads should be designed where appropriate to meet flood control inspection/patrol
and access requirements and where possible, should be combined with trails. This will reduce the
need for more frequent road maintenance, protect habitat in the Tassajara Creek channel, and
provide for public safety and police patrols. Low flow crossings or ramp access should be
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provided for maintenance; where an actual need is demonstrated. Access to the maintenance
roads should be designed to discourage unauthorized use. Single loaded streets along the creek
corridor may serve as maintenance roads for visual inspection by flood control staff.
Policy 6-12: ...Flood control maintenance practices will be
designed and performed to be responsive to public safety while
preserving-the unique riparian community. Maintenance
agreements (memoranda of understanding) between the City and
responsible agencies will address, but not be limited to, site
access, criteria for determining the needfor maintenance (i.e.,
assessment and monitoring), and the timing andfrequency of
actual maintenance practices.
Habitat Restoration
Habitat restoration ofthe stream corridor should be concentrated in the Tassajara Creek channel
where planting requirements, groun~water availability, wildlife use, and the hydrologic regime
dictate that such restoration occurs. Restoration should be accomplished through the use of plant
species native to the region that are adapted to local soil and microsite conditions, and capable of
becoming self-sustaining over the long-term. Restoration should emphasize prompt revegetation
of disturbed ar~as and should prohibit the use of invasive exotic species. Restoration plans
should be developed and implemented by professional revegetation specialists. Restoration
phmtings should be emphasized in reaches of the creek and its tributaries in the following
situations: 1) sites that are currently support very little native vegetation, or after grading, will
have large bare soil areas; 2) areas that require stabilization that native vegetation can provide;
3) locales dominated by invasive exotics that should be eradicated, or lack sufficient native plant
diversity; and 4) areas used for habitat mitigation.
Policy 6-11: All stream corridors, as shown in Figure 6.2, shall be
revegetated with native plant species to enhance their natural
appearance and improve habitat values. Revegetation must be
implemented by a professional revegetation specialist.
Policy 6-22: All areas of disturbance should be revegetated as
quickly as possible to prevent erosion. Native trees (preferably
those species already on site), shrubs, herbs, and grasses should
be used for revegetation of areas to remain as natural open space.
The introduction of non-native plant species should be avoided.
Specimen Tree Protection
Flood control constructioI) within the stream corridor and riparian restoration within the
Tassajara Creek channel should protect any existing native vegetation, including any native trees,
where feasible.
Policy 6-21: Direct disturbance or removal of trees or native
vegetation cover should be minimized and should be restricted to
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improvements.
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\Vildlife Enhancement
Wildlife enhancement should be accomplished through restoration of riparian habitat in the
Tassajara Creek channel, adequate setbacks from structures and trails, and design provisions to
allow wildlife movement through the Tassajara Creek corridor. Wildlife using the Tassajara
Creek corridor will benefit from both habitat enhancement of disturbed areas and habitat
mitigation, where new habitats are created from upland areas. Restoration should emphasize use
of a diversity of native species and habitat structure known to occur in local riparian wildlife
habitats, replacement of exotic plants with native plants, and the creation of setbacks or buffers
between riparian habitat .in the creek channel and public access and structures. Bird habitat can
be enhanced by planting native trees and shrubs along the trail right-of-ways and in adjacent
development, especially parks.
Policy 6-10: Riparian and wetland areas shall be incorporated
into greenbelt and open space areas as a means of preserving their
hydrologic and habitat value. Unavoidable loss of riparian habitat
due to development should be replaced with similar habitat on a
3: 1 inkind basis. Loss of wetlands must be mitigated consistent
with the ACOE's current policy.
Biological Corridor Connections .
The value of the stream corridor for !egional wildlife will be maintained as habitat restoration
proceeds and development occurs within the Eastern Dublin Specific Plan Area. Tassajara Creek
functions as a major regional wildlife corridor, providing uninterrupted connections to Hidden
Valley, Mt. Diablo, Morgan Territory, and Camp Parks, Black Diamond Mines and Contra Loma
Regional Park~, among other open space areas. Tassajara Creek should be buffered by stream
corridor setbacks establisli.ed by flood control requirements and consistent with biological
criteria. Biological corridor connections from Tassajara Creek to open space within the Specific
Plan Area should be provided through the major tributaries draining to Tassajara Creek, and
should be protected by restoration and setbacks from structures. Where the wildlife connections
along Tassajara Creek or its tributaries would be impeded by road crossings or other
development, wildlife underpasses should be provided to mitigate impacts.
Policy 6-1: Establish a continuous open space network that
integrates large natural open space areas, stream corridors, and
developed parks and recreation areas.
Policy 6-2: Locate development so that large, continuous open
space areas/corridors are preserved Avoid creating open space
islands. Encourage single loaded streets in areas adjacent to open
space, rural residential, and agricultural lands.
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Policy 6-18: Development in the planning area will be designed to
maintain contiguous areas of natural open space interconnected by
functional wildlife corridors, that permit the free movement of
wildlife throughout the open space areas. As a means of preserving
wildlife corridors, cluster development is generally preferable to
an even low-density sprawl over an entire area.
Policy 6=19: Where roadways divide open space areas,
underpasses or other means of access shall be provided to
facilitate the movement of wildlife without barriers.
Fencing Within Stream Corridor
Fencing within the stream corridor should be designed to restrict trail access by non-maintenance
vehicles, and discourage vandalism and undesired pedestrian or vehicular entry into unsafe or
sensitive wildlife habitat areas. Fencing should not restrict or impair wildlife movement within
the stream corridor and its tributaries or between the corridor and adjacent open space areas.
Fencing may be used to funnel wildlife movement into safe passage and away from roads or
other hazards.
Accommodate Mitigation Within Corridor
Owners should be allowed to provide for mitigation in the stream corridor for in-kind impacts
elsewhere within the Eastern Dublin Specific Planning Area. The area supporting high value
habitat including northern riparian forest, arroyo willow riparian woodland, and freshwater marsh
within the Tassajara Creek channel can be expanded as consistent with local site conditions.
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The Specific Plan's Policy 6-15 states that development of high
value habitat including northern riparian forest, arroyo willow
riparian woodland and freshwater marsh should be avoided, and
Policy 6-16, states that these high-value habitat areas should be
dedicated as public open space or restricted from potentially
harmful development with deed restrictions and design standards.
Flood Hazard
The design and implementation of the flood control channel within the stream corridor should
account for storm water conveyance and sediment loads, channel crossing, maintenance access,
and the natural scour and meandering of Tassajara Creek and its tributaries. The configuration of
the stream corridor cross-section should allow for the protection, establishment and maintenance
of native plant. communities in the Tassajara Creek channel. Except where energy dissipators or
bioengineering treatments occur, the creek bottom should consist of natural materials.
Policy 6-12: Maintain natural open stream channels to carry
storm runoff wherever feasible, rather than replacing with
underground storm drainage systems...use retention basins rather
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than channelization, if channelization is necessary, design so .
riparian vegetation can be established.
Policy 9-7: Require drainage facilities that will minimize any
increased potential for erosion or flooding.
Policy 9-8: Require channel improvements consisting of natural
creek bottoms and side slopes with natural vegetation where
possib-Ie tl:Tmeet Policy 9-7.
Channel Stability and Erosivity
Tassajara Creek channel and bank modifications should accommodate projected flood flows and
stream meandering, should employ bioengineering alternatives where appropriate, support native
riparian communities and result in a stream channel that has a natural appearance. Where
appropriate, the Tassajara Creek channel may be left to naturally meander within a setback
designed to accommodate long-term channel changes.
Program 61: The City should negotiate with Zone 7 the level of
flood control improvements required to meet district standards and
rights-ol-way requirements and maintenance responsibilities.
Water Quality of Runoff and Groundwater
The quality of groundwater and urban runoff into Tassajara Creek and its tributaries should meet
Best Management Practices (BMPs) and other standards as described in section 9.3.2 of the .
Eastern Dublin Specific Plan. Water quality impacts associated with cattle should be reduced as
cattle are grazed and watered at alternate sources outside the stream channel, as described in the
City of Dublin's Grazing Management Plan. Riparian habitat enhancement and restoration, as
well as landscaping in the development interface, should stabilize surface sediments.
Program 9A:...Require all developments to meet the BMPs of the
MOU Regarding Urban Water Conservation in California, of
which DSRSD is a signatory.
Policy 9-9: Plan facilities and select management practices in the
Eastern Dublin Specific Plan area that protect and enhance water
quality.
Reclaimed Water
The use of reclaimed water to irrigate restoration plantings or trail landscaping should not impair
water quality standards.
Program 9B:...lmplementation of DSRSD and Zone 7 findings and
recommendations on uses of reclaimed water to augment existing
water supplies.
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Regulatory Compliance.
Development in the Eastern Dublin Specific Planning Area, and restoration in Tassajara Creek,
its tributaries or other jurisdictional areas should proceed in full compliance with the regulations
and policies of all regulatory agencies with oversight responsibility in this area, including
California Department ofFish and Game, Army Corps of Engineers, United States Fish and
Wildlife Service, and the Regional Water Quality Control Board. No net loss of wetlands should
be allowed.
Policy 6-9: Natural stream corridors, ponds, springs, seeps, and
wetland areas, as shown in Figure 6.2, shall be preserved
wherever possible. Prior to submittal of development applications,
the appropriate agencies such as the California Department of
Fish and Game and the Army Corps of Engineers must be
consulted to determine whether they have jurisdiction over the
watercourse or wetland area.
Policy 6-10:...Loss of wetlands must be mitigated consistent with
the Army Corps of Engineer's current policy.
Program 6K: The City of Dublin shall establish and maintain a
liaison with resource management agencies (i.e., CDFG, USFWS,
ACOE) for the purpose of monitoring compliance with specific
plan policies. These agencies should be consulted and involved
throughout the planning and development process of individual
properties in order to avoid violations of state and federal
regulations and ensure that specific issues and concerns are
recognized and addressed.
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OPPORTUNITIES AND CONSTRAINTS
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. 3.0 OPPORTUNITIES AND CONSTRAINTS OF THE SPECIFIC PLAN AREA
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The rich resources of the Specific Plan study area offer unique opportunities for restoration of the
stream corridor, flood control planning for the watershed, and regional planning integrating
urban and natural environments. COI:nprehensively addressing these issues will also pose some
constraints to planning in the eastern Dublin Specific Plan area.
Restoration treatments in the Tassajara Creek corridor and its tributaries will be constrained by
existing condi~ions and the modifications required by Zone 7 to accommodate 100 year storm
flows. Restoration opportunities will vary between the three reaches of Tassajara Creek and the
tributaries, as a function of current conditions, project goals and proposed modifications. The
three reaches have been defined as: lower reach (Highway 580 to Gleason Road), middle reach
(Gleason Road up to and including the East Bay Regional Park District staging area), and upper
reach (East Bay Regional Park District staging area to the County line). Restoration opportunities
in each of these reaches will be defined by the necessary setbacks from existing or created stream
corridor, the extent of grading and channel modification required for flood control or the lack
thereof, surrounding land uses, the extent of existing native vegetation and wildlife habitat, the
distance to the water table, and trails and maintenance road placement. The opportunities and
constraints presented by the Tassajara Creek stream corridor are discussed in this report,
subdivided into sections addressing hydrologic resources, planning and biological resources.
This is followed by discussion of each of the three reaches.
3.1 Opportunities and Constraints: Hydrology, Hydraulics and Water Quality
3.1.1 Flood Hazard
Protection of lands adjacent to Tassajara Creek from flooding is a part of any development
planning. A detailed hydraulic study, i.e., a HEC-2 analysis, which estimates the flood flow
conveyance capacity of the channel, has been conducted for the lower reach below Gleason Road
by County of Alameda consultants. In this reach, preliminary approval has been obtained from
Zone 7 for a plan to expand or reconstruct the creek channel including the removal of a drop
structure just downstream of Highway 580. In the middle and upper reaches, above Gleason
Road to the County line, HEC-2 modeling still remains to be done. If existing capacity is
inadequate, alternatives to be considered include: channel alterations such as broadening,
deepening, or smoothing the channel, building levees to protect low-lying areas, and constructing
bypasses including surface channels and pipes.
Zone 7 ofthe Alameda County Flood Control and Water Conservation District is the agency
which may review and approve any hydraulic studies of Tassajara Creek. However, the City of
Dublin may contract with others to evaluate Tassajara Creek hydraulics for channel which will
not be under the ultimate control of Zone 7.
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3.1.2 Runoff Water Qualitv
In order to ensure good quality runoff water from developed areas, including the Specific Plan
Area, the Regional Water Quality Control Board and related agencies have promulgated a suite
of recommended measures to be incorporated as needed in each large project. In addition to
protecting water quality, these Best Management Practices help protect the aquatic habitat. The
City of Dublin. Department of Public Works permitting process requires that these measures,
which include erosion control among many others, be planned in detail and implemented for both
periods of construction and as a permanent part of any development.
3.1.3 Channel Stability and Erosivity. Setbacks
Natural channels erode and migrate. Typically this is a slow long-term, but relentless, process.
But it can be sudden. One may envision the area affected as being a corridor the width of the
widest part of the overall channel plus a substantial setback for sinuous meandering channels
which typically move laterally, braided streams which are subject to evulsions (i.e. rapid
unpredictable abandonment of a channel segment and creation of another some distance away),
and banks which may collapse. Channel alterations, including grading, vegetation removal, and
changes in the hydrologic regime due to development, can alter these natural processes.
Provisions need to be made for the movement of meanders, evulsive channels, erosion and
stabilization of banks, and control of channel deepening, known as downcutting. Much of this is
accomplished through appropriate setbacks. The desirable setbacks for hydrologic purposes and
improved property protection may coincide fairly closely with wildlife and other structural
setbacks or be larger. This is discussed more fully in the guidelines section below. Thus the
protected stream corridor, as mandated by the Specific Plan, is likely to become a valuable multi-
purpose amenity to the community, based on a consistent set of setbacks which serve several
planning purposes.
3.1.4 Reclaimed Water
There is an opticm for consideration of the use of reclaimed water for irrigation in the Tassajara
Creek corridor and on its watershed lands. Supplies of reclaimed water may be readily available
from the Dublin San Ramon Services District. Although the use of reclaimed water is
encouraged by the state, various technical matters are currently in review related to the protection
of groundwater quality in Livermore Valley. Zone 7 is the lead local agency which will provide
input on constraints applicable to the use of reclaimed water.
3.2 Opportunities and Constraints: Planning
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3./.] Proposed Land Uses
The Specific Plan proposes a variety of uses along the three reaches ofTassajara Creek. The
Specific Plan locates a number of destinations and uses near the stream corridor into which
important trail connections need to be made to ensure the desired level of pedestrian and bicycle
circulation. The policies of the Specific Plan encourage the establishment of a continuous open
space network that integrates large natural open space areas, stream corridors, and developed .
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parks and recreational areas. The stream corridor runs the entire north/south length of the plan
area on the western edge. This stream corridor offers a tremendous opportunity for trail and open
space connections linking schools, parks, commercial centers, and other open space areas.
Pedestrian access to this corridor can be emphasized by encouraging streets that open up on the
creek or are single loaded against the creek, giving the neighborhoods a highly valued character,
and providing convenient access to open space and trail connections of the stream corridor.
Numerous Specific Plan policies address planning for the stream corridor and adjacent
development, resulting in both opportunities and constraints.
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As required in the Specific Plan, meetings were held with staff members of East Bay Regional
Park District (EBRPD), Zone 7, California Department ofFish and Game, and the City of Dublin
to determine requirements that would constrain construction of adjacent development, trails,
roads and maintenance facilities within the Tassajara Creek corridor. The City of Dublin's Parks
and Recreation Master Plan also provided direction for the City requirements discussed below.
East Bay Regional Park District Through meetings and correspondence, East Bay Regional Park
District has expressed interest in having a regional trail, limited to one side of the creek only, as
part of the East Bay Regional Park District trail system, extending from Dublin Boulevard to the
County line. This trail should provide a trail connection from the East Dublin BART/Iron Horse
trail to Tassajara Creek along the north side of Dublin Boulevard. Provisions for a potential trail
connection under Highway 580 to Pleasanton through County property should be made.
East/west trail connections to Tassajara Creek should be planned for, as shown in the Eastern
Dublin Specific Plan. Plans for local access points to the trail and significant destinations or land
uses should be made. The trail should be multi-use, accommodating bikes, pedestrians and
equestrians. To accommodate all these uses, the paved trail should be ten feet wide with two
adjoining unpaved shoulders, with one of shoulders to be f.Qur to six feet wide, and the other two
feet wide, covered with decomposed granite. The City's higher standard of a twelve foot paved
trail is acceptable to the District.
The multi-use trail would transition to the existing unpaved trail at East Bay Regio.pal Park
District's Tassajara Creek staging area. East Bay Regional Park District has requested that the
trail to be located above the flood plain terrace to facilitate emergency vehicle access and patrols,
provide for public safety, minimize wildlife disturbance and reduce maintenance requirements
follov-.ring flood events. East Bay Regional Park District typically maintains their non-irrigated
naturalized vegetation adjacent to trails within their jurisdiction by mowing, and therefore
recommends against plantings that have the potential to grow onto the trail and shoulder, require
irrigation and cultural treatments, impair visibility or movement, or interfere with their ability to
mow.
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East Bay Regional Park District requires provision for a single primary staging area. It is
assumed that the existing staging area will provide needed equestrian access and other staging .
needs. In the upper reach of Tassajara Creek where the banks are steep and high, East Bay
Regional Park District will want to discourage access to the creek banks to minimize impacts to
riparian habitat while providing for public safety. Planning treatments in this reach should
consider: locating the trail at the outside of the established setback, redirecting drainage above
the creek banks, strategically placed fencing, proper signage, removal of large debris or rubble,
reducing cattle. watering in the creek, and localized repairs of soil sinking (piping).
East Bay Regional Park District recommends that streets be limited to a single-loaded street plan
adjacent to the creek. Options for combining Zone 7 access roads with the trail to reduce the need
for multiple roads next to the creek should be explored. The creek should be maintained in as
natural state as possible to protect and enhance wildlife corridor values. Major road crossings
should be designed to accommodate trails. Furthermore, traffic analysis should be conducted to
determine appropriate mechanisms for at grade trail crossings to ensure public safety. Traffic
improvements could include: stripped crossings, flashing yellow lights and fully signalized
crossmgs.
Zone 7 Zone 7 is interested in taking ownership of the lower and middle reaches if their flood
control mandate is met (i.e., 100 year flood flows with one foot of additional elevation, know as
freeboard) and their maintenance requirements are satisfied. Their maintenance requirements
include: continuous access on both sides of creek with an all-weather maintenance road. The
maintenance road must be a minimum of 15 feet wide with a four inch compacted aggregate
base, and an additional two and one-half feet of clearance on either side of the 15 foot road. They
require a minimum 20 foot structure setback from the flood control channel (QI00), but prefer 30
feet, and where controlled access for maintenance is feasible from adjacent parking areas or
single loaded streets, the road may be interrupted. BotJ:1 roads should be above the Q 100 within
the structure setback. If this is not practical, Zone 7 :may accept one road closer to the creek
channel, above the Q15. If a lower road is provided, it should be concrete paved or asphalt
concrete. Access must be controlled and maintenance ramps to the low flow channel may be
necessary at certain locations.
Zone 7 has some Special Drainage Area (SDA) funding to take ownership of a portion of the
lower reach, from Highway 580 to Gleason Road, insofar as SDA funding is available. Current
SDA 7-1 funding is provided for the Highway 580 to 3,000 feet northward, and the program will
be reassessed in 1996, which may extend the program to cover a larger area. Zone 7 reviewed the
site conditions of the upper reach and concluded that the severely eroded steep banks and other
site conditions preclude their ownership. Zone 7 is a strong candidate to own the lower and
middle reaches, should funding become available. Should Zone 7 acquire the lower and middle
reaches, these reaches may be subject to a routine standing joint use agreement which allows
them to release liability and open their facilities to the public for park and recreation use. Thus
the City of Dublin could manage the lower and middle reaches of Tassajara Creek as open space
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accessible to the public although Zone 7 would own the land. Combining trails with maintenance
roads is acceptable to Zone 7.
City of Dublin The City of Dublin is interested in having East Bay Regional Park District and
Zone 7 take ownership and management of portions of the stream corridor. In general, the City
wants trails to accommodate more than one type of trail use, construct trails designed to require
as little maintenance as possible over time, and to avoid steep inclines.
The trail along Tassajara Creek should be designed to serve as a "Class I Bikeway", providing
for bicycle travel on a right-of-way completely separated from any street or highway. Trail
standards are described in the City of Dublin Parks and Recreation Master Plan. Given the
combined bicycle and pedestrian uses along the trail, the width of the trail should be at least 12
feet. City Public Works recommends that a cleared two-foot wide shoulder on both sides of the
trail. The easement for the trail should be a minimum 25 feet wide along major streets or
parh."Ways and a minimum of30 feet'wide where private property abuts on both sides. \\Then
crossing an arterial street, the crossing should occur where motorists can be expected to stop.
Traffic signs for bicyclists should be installed. CalTrans standards should be used for signage
and speed controls.
California Department of Fish and Game The Eastern Dublin Specific Plan specifies that the
California Department ofFish and Game be involved in the development of the Comprehensive
Stream Restoration Program. The Department's standards for development includes a minimum
100 foot setback from the top of the bank of Tassajara Creek to protect biological and
hydrological resources, unless an exception .is negotiated with the Department. California
Department ofFish and Game provided comments during the CEQA process for the Eastern
Dublin Specific Plan area. The Department should be expected to review and comment on all
future plan submittals to the City ofDllblin, for properties adjacent to the Tassajara Creek, its
tributaries, other wetlands and other sensitive habitats, as well as sensitive plant and wildlife'
speCIes.
3.3 Constraints and Opportunities: Resource Protection, Restoration and Mitigation
3.3.1 Existing Biotic Resources
Existing biotic conditions are fully described in section 3.7 of the EIR for the Specific Plan and
biological resources studies conducted by H.T. Harvey and Associates between 1990 and 1993
for the Dublin Ranch owned by the Lin family. Although most of the plan area is dominated by
non-native grassland and dry farming cropland, there are sensitive resources, the protection of
which will impose constraints to development. The EIR includes teA1 discussions and maps
noting the locations of red-legged frog populations, an active golden eagle nest, other raptor
nests, western pond turtle populations, alkali grasslands, wetlands, springs, seeps and ponds,
riparian and other sensitive habitats. This stream restoration program focuses on protection and
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enhancement of these resources to benefit local and regional v..rildlife, and enhance their value to
the area's residents.
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3.3.2 Resource Protection. Restoration and Mitigation
Sensitive biological resources such as the red-legged frog and western pond turtle populations,
golden eagle nest, raptor nest, wetlan~ riparian and aquatic habitats should be protected during
the course of development in the Specific Plan area. Impacts to these sensitive resources will
have to be mitigated, with the regulatory agencies. The implementation guidelines section on
regulatory compliance covers the procedures and agency requirements in detail. The agencies
-that will issue permits ar.d/or require mitigation will include California Department ofFish and
Game, Army Corps of Engineers, and Regional Water Quality Control Board. The Army Corps
of Engineers will require permits to "fill" wetlands or waters of the U.S. The Department ofFish
and Game will require a 1601-3 Streambed Alteration Agreement and mitigation of impacts for
stream crossings. The Regional Water Quality Control Board will enforce its "no net loss of
wetlands" policy, requiring mitigation and acquisition of a certification or waiver for Army
Corps of Engineers permitting. Impacts to sensitive habitats including wetlands, and waters of
the U.S. will require at least 1:1 replacement, while tree removals will require replacement at 2: 1,
3: I or higher ratios, depending on the type of trees and habitat in which the removed trees were
located.
3.3.3 Biological Corridors
Development around and adjacent to Tassajara Creek and its tributaries will be constrained to .
protect the value of the riparian corridor as a regionally significant wildlife movement corridor,
which provides uninterrupted connections to Hidden Valley, open space areas in Tassajara
Valley, Mt. Diablo State Park, Morgan Territory, Camp Parks, Black Diamond Mines and Contra
Loma Regional Parks, and other open space areas. Development constraints to protect the value
of the riparian corridor for wildlife movement include: 1) a minimum wildlife setback on each
side ofTassajara Creek, and along minor and major tributaries; 2) the construction of wildlife
underpasses arroad crossings on Tassajara and its tributaries; 3) restoration plantings in the
riparian corridors; and 4) landscaping to provide functional and aesthetic transitions along the
biological corridor, trails and adjacent development.
Protection and enhancement of the biological corridor presents opportunities to maintain the
functional value of the riparian areas for wildlife, and preserving habitat for resident and
migratory wildlife species that make this area unique. In addition, opportunities arise for bird
'watching, interpretation, other passive recreational uses, and the integration of natural elements
in an urbanizing setting.
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3.3.4 Invasive Exotic Plants
The presence of extensive stands of invasive exotic plants both in and adjacent to the Specific
Plan area provide an extensive seed bank that will affect future restoration and enhancement
plantings. Exotics are known to compete for water, space and nutrients, often resulting in
mono cultural stands that have little to no benefit to wildlife. Non-native annual grasses are an
exception and should be tolerated in this system, since the grasslands do provide wildlife habitat
and conversion to native grasses in this region is infeasible. The presence of noxious weeds will
necessitate extensive eradication work. Without well-planned and consistently implemented
exotics eradication, restoration plantings will have limited success as they will be overtopped by
aggressive exotics. To minimize the impact of exotics on restoration and enhancement plantings,
landscaping along the trail and elsewhere adjacent to the wildlife corridor will be limited to those
plants listed in the plant palette and plants compatible with native oaks. Plants that would be
likely to invade the riparian corridor should not be planted in restored or landscaped areas
because of their propensity to spread, and a list of commonly used plants that should not be used
in this area are listed in the restoration guidelines. Landscaping along trails will provide
opportunities to extend the upland habitat and create a transition between adjacent development
and the Tassajara Creek corridor. .
Dense stands of exotics within the Tassajara Creek corridor also present an opportunity to
reclaim these areas to native species that will provide improved wildlife habitat and aesthetic
character. .
3.3.5 Specimen Trees
All three reaches of Tassajara Creek support numerous mature native specimen trees, including
live oak, valley oak, bay, buckeye, cottonwood, boxelder and more. Great effort should be made
during the design and construction of the flood plain terrace, roads and trails and other flood
control improvements to protect these trees, and ensure that they will continue to.thnve in the
future. Decisions regarding which trees have to be removed for flood control and roadltral:l
construction should be made on an individual basis, with 3: 1 replacement for all riparian trees
(willow, cottonwood and alder) regardless of diameter at breast height (DBH). Other species
should be replaced at a 3:1 ratio for individual trees greater than six inches DBH. Non-native tree
species, such as eucalyptus, tree-of-heaven and black locust should be replaced with native trees
at the 3: 1 ratio, since native birds are known to nest in these exotics trees.
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3.3.6 Soils .
Based on the vegetative indicators present throughout much of the Tassajara Creek corridor, soils
appear to be very compatible with riparian plantings. An exception to this generalization are
alkaline soils characterized by the presence of remnant alkali grasslands in the northeast portion
of the plan area. In these areas, restoration and enhancement plantings should be limited to those
species that can tolerate alkaline soils,such as native saltgrass.
Elsewhere, native riparian vegetation is found in varying densities in creekside locations
throughout the plan area. The densit)1 of riparian vegetation does not appear to be related to soils,
as much as grazing, recent grading and the prevalence of summer water in the channel. Until
soils testing is conducted however, the presence of soils-related constraints cannot be ruled out.
The presence of soils that presently support native riparian vegetation appear to present excellent
opportunities for enhancing native habitat through restoration plantings. The existence of alkaline
soils should be viewed as an opportunity to enhance these naturally occurring communities,
rather than as obstacles to riparian plantings that are not adapted to this type of soil.
3.3.7 Proiect Scheduling and Phasing
Implementation of the restoration plantings and flood control improvements discussed in this
document will occur over an extended period of time, with activity focused on different portions
of the project area over time. Because activities along the Tassajara Creek corridor and tributaries
'will be phased, coordination between project proponents to ensure implementation of all relevant .
portions of this plan will be needed.
3.4 Opportunities and Constraints of the Three Reaches
Restoration treatments in the Tassajara Creek corridor and its tributaries will be constrained by
existing conditions and the modifications required for flood conveyance. -Three reaches (Figure
2), spanning 16,100 linear feet have been defined as: the lower reach (Highway 580 to Gleason
Road), the middle reach (Gleason Road up to and including the East Bay Regional Park District
staging area), and the upper reach (East Bay Regional Park District staging area to the County
line). The exiting conditi0ns and the intended channel modifications of Tassajara Creek vary
greatly among the three defined reaches, and therefore require consideration and analysis
appropriate to the particular reach.
3.4.1 Lower Reach
Zone 7 proposes to acquire the corridor from Highway 580 e:>...1ending northward 3,000 feet.
Additional funding may allow Zone 7 to acquire a longer corridor. The lower reach owned by the
County of Alameda, was further divided into two subreaches: Subreach 1 extending from 1-580
to Dublin and Subreach 2 extending from Dublin to Gleason (Figures 3a and 3b). A proposed
plan for the lower reach includes removal of the 70 inch-high drop structure at Highway 580. In
Subreach 1 the County of Alameda is proposing creation of a trapezoidal channel, a meandering
low flow channel, two maintenance roads above the Q1 00 on either side of the channel, 100-foot
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setbacks from the existing top of bank, restoration plantings below the Q 15, and landscape
plantings above the Q 15. Additional landscape easements outside the Q 1 00 will be maintained by
adjacent commercial development.
In Subreach 2 the County of Alameda is proposing avoiding disturbance to the incised creek
channel, creation ofa flood plain terrac~t the Q15level on either side ofTassajara Creek to
contain 100 year flood flows (Brian Kangas Foulk, 1995), a regional trail/maintenance road on the
east side of the channel above the QI00, a local trail/maintenance road on the west side of the
channel above the Q100, setbacks from the existing top of bank averaging 100 feet, restoration
plantings below the Q15, and landscape plantings . Landscape plantings that may require
permanent irrigation due to the distance from groundwater table, are proposed in the trail right-
of-ways and on the flood plain terrace.
Zone 7 has indicated that because of high anticipated flow velocities and unstable soils, bank
stabilization may be needed in several locations. Straightening or otherwise increasing the
stream's slope would tend to encourage the channel to develop into a fully braided pattern (wide
and shallow) which is usually associated with the undercutting of banks and bank retreat,
requiring significant protection measures (Dunne and Leopold, 1978, p. 626). Although Zone 7
would prefer to spray the riparian vegetation with herbicides to limit the growth of willows, they
may not require it. Other design options which may involve different ownership of this reach, but
provide the same flood conveyance, are possible. The proposed Brian Kangas Foulk plan
generally conforms with these restoration guidelines, provided that the restoration plantings are
established below the Q15 and that the lOa-foot setbacks are implemented, and Zone 7 flood
control and public safety issues are addressed, including the potential evulsive nature ofTassajara
Creek.
This lower reach will require regrading and modifications to create the flood control channel and
flood plain terrace outside the existing channel to carry the higher flows. This reach is also unique
because of the surrounding intended land uses. Between Highway 580 and Dublin Boulevard,
general commercial is proposed on the west side, and office on the east side .of the creek. Above
Dublin Boulevard the surrounding intended land uses are characterized by medium and medium-
high density residential, an elementary school, a city park to the east, and an industrial park on the
west side near Gleason Road. The setbacks along this reach are likely to be controlled by the
wildlife and structure setbacks, rather than hydrologic considerations. The development interface
along this reach is significantly different than the interface in the middle and upper reaches, where
the surrounding land uses will be primarily residential. The regional trail connection from BART is
intended to connect to the creek corridor at Dublin Boulevard within this lower reach. All stream
corridor crossings should be accommodated by existing or proposed roadways.
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In the lower reach, plantings over much of the reach will be possible because of the extent of
existing disturbance, and modifications required to accommodate flood capacities. The creek
channel provides many opportunities for establislunent of a diversity of riparian species. The
flood plain terrace is expected to support only non-irrigated low maintenance grasses and low-
growing perennials because of the distance to the water table. The County of Alameda has
proposed to establish landscape trees-2bove the Q 15 on Sub,reaches 1 and 2 ; these may require
permanent irrigation and are consistent with the restoration guidelines. Efforts to preserve the
specimen oaks along the channel will constrain grading procedures. The structure setback will
provide opportunities to plant upland tree and shrub species, compatible with the creek
environment. Sufficient groundwater may not be available for dense riparian plantings for the
entire lower reach because the supply may be lost through sandy substrate into the Livermore-
Amador Valley groundwater (David Lunn, Zone 7 personal communication). To some degree
this phenomenon may be offset by the increased summer water supply from future upstream
development.
3.4.2 Middle Reach
Between Gleason Road and the East Bay Regional Park staging area is a 5,000 foot long
vegetated channel which appears adequate for 1 DO-year flood conveyance. However, detailed
hydraulic analysis, presumably using the HEC-2, will be required by Zone 7. If channel capacity
is inadequate, flood conveyance alternatives will need to be considered, such as channel
alterations, levees, or bypasses. Zone 7 does not recommend the use of levees in this area.
Proposed treatments should transition to the approach adopted in the lower reach by the City of
Dublin and Zone 7. As mentioned below in the section on setbacks, additIonal hydrologic studies
are warranted to determine the overall stability of the channel.
Compared to the lower reach, the appearance of this reach is more natural, with stream meanders,
well-defined channel bed and bank, well-established riparian vegetation, and significant
topographic features along the westerly edge. The intended land uses in this reach are-
characterized by medium density residential, a junior high school, public/semi public, and the .
East Bay Regional Park District staging area and a neighborhood park. The residential
development interface with the stream corridor should incorporate single loaded streets, cul-de-
sacs or loop streets that open onto the stream corridor. Local trails linking the regional trail with
the junior high school arId the neighboring residential park to the east should be provided.
Crossings of the stream corridor should be at the junior high school and the staging area.
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The middle reach has fewer opportunities than the lower reach for restoration treatments because
it is already densely vegetated with native riparian species. Much of this reach probably will
accommodate the 100 year flood flows, necessitating less disturbance of the channel. Those
sections of the middle reach requiring modifications to create a flood plain terrace will be
identified through a deta:led hydrological analysis, and depending upon the degree of disturbance
to the creek banks, restoration plantings will be indicated. Additional restoration opportunities
'will exist for those areas cleared of debris and stands of exotics that are eradicated. As in the .
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lower reach, the flood plain terrace will support grasses and perennials, and the structure setback
will support upland species.
3.4.3 Upper Reach
Tassajara Creek, north from the East Bay Regional Park District staging area to the County line,
is a 7,000 foot long channel with a meandering channel form, with locally steep and actively
eroding banks. It is a dramatic reach frequently wooded and varied in appearance and often with
near-vertical banks over 40 feet high. It is preferable to leave the upper reach as a natural
channel with adequate setbacks for structures and public safety, where it can be a valued local
resource. Based on field reconnaissance, flood conveyance should be adequate through the
channel for most or all of this incised reach. Substantial setbacks seem indicated to protect
structures and improvem~nts from bank retreat and channel migration. The setbacks are also
relatively greater than in other reaches because the channel is deeper. Alternatively, the applicant
may propose to stabilize sections in the upper reach to reduce hydrologic setbacks. Should an
engineering alternative be proposed, it should receive close review and comment from the City
of Dublin, Zone 7, Army Corps of Engineers and California Department ofFish and Game. An
engineering alternative should be reviewed for the potential to trigger a transformation ofthe
creek channel, which may be evulsive (see Section 4.6).
This reach contains a channel that is. significantly different than either the lower or middle
reaches. As mentioned, the channel is very deep and wide with steep banks and it contains some
pockets of dense riparian vegetation. The intended land uses in this reach are characterized by
medium density residential, single family residential, medium-high residential, neighborhood
park, an elementary school to the west and a neighborhood square to the east. The residential
development interface with the stream corridor should incorporate single loaded streets, cul-de-
sacs or loop streets that open onto the stream corridor. Local trails should be provided that link
the elementary school, commercial area, neighborhood square, residential areas and the regional
trail. Stream crossings in this reach should be incorporated with proposed roadway crossings.
Safety is a concern for users of the trail system along the top of bank and safety should be
considered in designing the trail setbacks and treatments.
Restoration opportunities in the upper reach will be ex1ensive once grazing pressure on riparian
vegetation is reduced. Extensive plantings along the low flow channel 'will be possible, as well as
plantings of riparian and upland species further above the groundwater table. Restoration
treatments could extend beyond the current top of bank and could include areas of alkaline
grassland. Restoration treatments in the upper reach of Tassajara Creek wil1 be constrained by the
presence of cattle before grazing along the creek is phased out. In many areas, vertical banks are
inappropriate for plantings.
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RESTORATION GUIDELINES: HYDROLOGY,
HYDRAULICS, AND WATER QUALITY
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4.0 RESTOR.\TION GUIDELINES: HYDROLOGY, HYDRAULICS AND WATER
QUALITY
4.1 Introduction
Tassajara Creek corridor is a riparian ecosystem consisting of a diversity of habitats and
microclimates, and serving a host of eeological, aesthetic, hydraulic, and hydrologic functions.
The creek is an avenue for the movement of wildlife as well as the flow of water, the stream
corridor being the key regional environment where these elements concentrate and move. The
16,100 foot long Tassajara Creek cO)Tidor provides groundwater for riparian plants, aquatic
habitat for plants and animals, a means for conveying stream runoff and groundwater seepage
through and away from the area, a location for recharging groundwater, an aesthetic amenity, and
a spacious open area conducive to human enjoyment.
4.2 Reducing Flood Hazard
A key function of the corridor is its ability to contain and convey flood flows up to and including
the 100-year design flood. Nearly all storm runoff originates in the upstream portions of the
watershed, in Contra Costa County. There is only a small portion of the watershed for Tassajara
Creek contained within Alameda County. S~nce Zone 7 of the Alameda County Plood Control
and Water Conservation District is not desirous of any detention facilities (Jack Pong, personal
communication), channel conveyance of anticipated flood flows is the prime concern in
addressing flood hazard. It is the City of Dublin Public Works Director's understanding that
detention facilities may be beneficial if placed upstream in Contra Costa County.
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Preliminary evaluations by Balance Hydrologics suggest that in the middle and upper reaches of
the channel, above Gleason Road, there appears to be adequate channel conveyance for a 100-
year flood plus the one foot of required freeboard. In part of the lower reach, between Gleason
Road and Dublin Boulevard, there are plans to cut flood plain terraces adjacent to the existing
channel to provide 100-year design flow channel conveyance at a rate not to exceed 6 feet-per-
second in the constructed area, as specified for earthen channels in Zone 7' s Hydrology and
Hydraulics Criteria Summary for Western Alameda County. In the lowest reach, below Dublin
Boulevard, the channel needs to be deepened and Vvidened and/or terraced to accommodate the
proj ected design flow of 5,200 cfs (cubic feet per second) as established by the County of
Alameda Public Works Agency (see Appendix 1 in the Santa Rita Drainage Master Plan.) as
well as to adjust to the new grade created by the planned removal of the 70 inch-high drop
sL"11cture south of Highway 580.
Of course, additional HEC-2 modeling in the middle and upper reaches and possibly other
analyses should be conducted to demonstrate that the design flows can be conveyed in the
existing channel. If existing conveyance capacity is inadequate, then alternatives such as
broadening, deepening, and smoothing the channel should be considered as well as levees and
bypasses. Note that additional studies of channel stability will likely be required. Zone 7 will
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determine if flood conveyance is adequate for the channel through each individual property, .
based on detailed documents to be submitted by the applicant. Zone 7 will evaluate flood
conveyance on behalf of the City of Dublin for city areas, as well as evaluate it for reaches which
Zone 7 may consider for ownership.
In the lower reach between Highway 580 and Gleason Road, the corridor is expected to be
owned by Zone 7. Consequently, if thIs happens, Zone 7' s criteria for the acceptance of a
property with some possible minor site-specific exceptions will dictate the character and
dimensions of the channel as specified in the Alameda County Flood Control and Water
Conservation District's Hydrology and Hydraulics Criteria SummaJ}lfor Western Alameda
County. The engineering firm Brian Kangas Foulk has prepared the Santa Rita Drainage Master
Plan, including a channel design, and a HEC-2 model which describe the proposed total
reworking and enlargement of the flood control channel below Dublin Boulevard (Subreach I)
and cutting of a flood plain terrace to enlarge the conveyance capacity and slow flows between
Dublin Boulevard and Gleason Road (Subreach 2). Zone 7 is reviev.ring these plans and reserves
the right to request changes (Zone 7, Memoranda, 1995). With the exception of the existing
bridge undercrossings, which Zone 7 finds to be already adequate, the channel can be configured
as needed to meet conveyance requirements. Future geotechnical work during excavation may
expose erodable bank soils which will require stabilization. The existence or likelihood of active
downcutting should also be evaluated, particularly in light of the planned removal of the 70 inch
drop structure below Highway 580. \Veirs or other grade control structures may be needed to
limit the downcutting, which tends to destabilize banks and lower the groundwater table. In .
addition, the constrictive effects of restoration plantings recommended in the guidelines may
require a larger channel than previously planned. The guidelines also recommend a minimum
100 foot setback from the top of bank consistent with the Department of Fish and Game
standard, unless an .exception is negotiated with the Department. Setbacks are also discussed in
the restoration guideline sections for planning, and resource protection, restoration and
mitigation.
Flood conveyance capacity is usually estimated by use of the Army Corps of Engineers' HEC-2
model. It is based upon a series of variably-spaced cross-sections established through a very
detailed topographic survey of the channel. The model is especially detailed where there are
bends, bridges, channel narrowing, or other elements which tend to constrict or expand the flow,
or where there are low banks over which a flood may spill onto adjoining lands.
Flood channel capacity, required to be adequate for the 1 OO-year flood flow plus one foot of
freeboard according to Zone 7' s criteria, can be supplied by leaving the channel as is, enlarging
or altering all or part of the channel,.defining the extent of the floodplain by building levees,
and/or providing a bypass for a portion of the flow. The need for channel alterations is
established by initial calculations (usually HEC-2 modeling) and the effects of proposed changes
are shown in subsequent model runs. Zone 7 has already called for additional modeling below
Gleason Road .to examir:.;>: the impacts of various alternatives proposed by BKF in the Santa Rita
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Drainage Masler Plan. Above Gleason Road, a new detailed survey and HEC-2 model will be
necessary to ascertain other areas where the channel may not fully hold the 100-year design
event. For each below-capacity segment, all the alternatives proposed above should be
considered. Existing structures may pose some problems in terms of flood hazard alternatives in
some reaches.
It should also be noted that a regional detention basin for flood control is being planned in Contra
Costa County. The proposed facility, if built, will help assimilate flood flows and pulses of
sediment emanating from Mt. Diablo, where landslides and 'wildfires are recurrent (Holmes and
Hecht, 1992).
4.3 Runoff 'Vater Quality
Developed as well as natural lands have an impact on water quality. Storm runoff from streets,
buildings, and landscaped areas is contaminated with a host of constituents including oil, grease,
nutrients, pesti'cides, herbicides, heavy metals, sediment, oxygen demanding substances,
floatables, and bacteria and viruses. The greatest typical need is to protect the aquatic
environment from the acute (short-term) and chronic (longer term) exposures to toxic chemicals.
Similarly, the physical character of the water, including attributes such as temperature, dissolved
oxygen and the amount of suspended sediments, needs to be protected. The protection of surface
waters is mandated through the National Pollutant Discharge Elimination System (NPDES). It
involves a permit administered for the Tassajara area by the Regional Water Quality Control
Board under the auspices of the Clean Water Act, and the California State \Vater Resources
Control Board.
For any development exceeding five acres, a state permit is required from the Regional Water
Quality Control Board. The City of Dublin, in turn, will require the state permit prior to issuing
approval of grading and improvement plans. However, all developments require apPZ9val by the
City of Dublin Public Works Department which requires erosion control (ABAG, 1980) and the
installation of Best Management Pr~ctices (BMPs).
Measures for combating water pollution from developed area runoff are Best Management
Practices. BMPs are detailed in the California Storm Water Best Management Practices
Handbooks an~ Alameda. County documents recommended by the City of Dublin. The selection
and development of an appropriate suite ofBMPs is influenced by land use, terrain, runoff
source and volume, development type and extent, capital investment, local preferences by the
permitting agency, and other factors. There is a range of alternatives, most of which consist of
vegetated areas and ponds, which can concurrently provide an aesthetic amenity and open space
to the community. Other BMP measures in~lude: control of the use of and disposal of certain
substances, maintenance programs for drainage facilities, public education, recycling programs,
landscaping, spill prevention and containment, and dust control.
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Any development should expect to use approved BMPs both during construction and as a
permanent part of the development ipfrastructure. The BMPs are planned in the preparation of .
the project's Storm Water Pollution Prevention Plan (SWPPP), which must be approved by the
City of Dublin prior to the start of construction. Among the requirements established by
Ordinance No. 52-87, Establishing Requirementsfor Protection of Watercourses, is that a
written permit .is required prior to discharging into or connecting any pipe or channel to a
watercourse; depositing, planting or removing materials from a watercourse including its banks;
altering any structure in a watercourse; and causing flow to be diverted.
4.4 Soil and Groundwater Quality
Water quality of groundwater is influenced py local naturally-occurring minerals leached from
the substrate. Parts of Tassajara Valley have boron concentrations which are detrimental to
growth of most plant species. Other compounds may locally exist in problem concentrations. The
Soil Conservation Service's soil survey and Balance Hydrologics' reports (see reference
bibliography) include some applicable testing results. Groundwater and/or soils should be tested
to ascertain the presence of such chemicals prior to making any investments in restoration
planting, as discussed in the restoration guidelines for resource protection, restoration, and
mitigation. Zone 7 area (David Lunn, personal communication) and USGS (Glass, 1981) have
studied local groundwater quality. Findings indicate that groundwater supplies for plantings in
the lower reach may be severely limited, due to infiltration to the deep aquifer.
4.5 Erosion Reduction .
Development disrupts the soil surface and removes vegetation, exposing the soil to accelerated
erosion. Runoffvolume and speed is increased and often sent in new directions due to the higher
percentage of imperviouj surface area, removal of vegetation, smoothing of the slopes, and other
factors. In an effort to minimize the effects of construction on the aquatic ecosystems and to
protect the soil resource, erosion control is mandated as a part of constructiQn permits. Particular
efforts are made to provide buffers of undisturbed vegetation adjacent to streams.
A construction period erosion control plan (ABAG, 1980) is a part of the project's Storm \Vater
Pollution Prevention Plan (SWPPP) submittal to the City of Dublin. It provides for grading to be
limited to the dry season and for the protection of some natural vegetative cover. It also requires
that sediment traps be installed and maintained to protect watercourses, as well as other BMPs.
4.6 Channel Stability and Erosivity, Setbacks .
Natural channels and unlined channels constructed in earth are not static; they are intrinsically
unstable and dynamic. Tassajara Creek appears to be unusually unstable. A preliminary analysis
of the relationship of bankfull discharge (a flow that occurs on the average every 1.5 years) to
channel slope for the entire reach of Tassajara Creek, from the County line to Highway 580,
indicates that this is an unstable channel. It is a channel apparently in transition with reaches
shifting their channel patterns or habit. Based on the limited scientific data available to Balance
Hydrologies, it appears to be on the transition between meander and braided forms. This has
.
24
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serious implications for channel stability and definitely needs much more detailed study by a
qualified registered professional prior to establishing setbacks or altering the channel form. In
particular, any efforts to straighten or otherwise increase the longitudinal slope of the channel
may trigger a transformation to a significantly less stable form perhaps leading to evulsive
changes. The potential hazard presented by the instability of the stream corridor should not be
underestimated. Channel and bank st~Qility improvements should be designed to reduce or
eliminate the potential evulsive changes.
Streams can incise downward (downcutting), erode their banks (sometimes causing them to
collapse into the stream) and move laterally. The materials removed in these processes, be they
rock, earth, rubbish, concrete, trash, or vegetation, become a part of the stream and ultimately
must be deposited somewhere although they may first disintegrate into fine materials. Much
material moves through the creek system incrementally such as from pool to pool, from sand bar
to pool, or floats from tree to fence to bridge. Deposits can constrict the streamflow and thus the
local channel conveyance capacity.
The Tassajara Creek system is especially noteworthy from the vievvpoint of sediment, in that the
watershed heads on the slopes ofMt. Diablo, is relatively large in being over 25 square miles,
has many areas of active erosion, and consists mostly of steep wildlands which are locally
erodable, especially following recurrent wildfires and landslides. Thus sediment and vegetative
debris are important in terms of their potential influence on flood channel capacity. However
these are particularly episodic processes as indeed are flood flows. These factors are limitations
\vhich should be factored into flood control planning but which are not generally analyzed
directly. Zone 7 and Alameda County appear to have considered bed sedimentation and 'bulking'
in selecting a high-end value of 5,200 cfs for the anticipated 100 year design flow.
Since stream channels may move either downwards or migrate laterally the corridor width should
accommodate such naturally occurring movement. Stabilization is costly and its effects are
. somewhat unpredictable; often a stabilization measure in one part of the creek will exacerbate
problems elsewhere. Such hard structures can also be profoundly unaesthetic. On the other hand,
bioengineering or discrete use ofbo~ders and/or vegetative cover can provide the necessary
stabilization, or provide an effective camouflage for a hard structure. Bioengineering is described
in the restoration guidelines section for resources protection, restoration, and mitigation.
Setbacks are a.more suitable primary measure to accommodate the relatively low rates of channel
migration which prevail regionally. They are an essential means of protecting structures and
property. Vertical incision or downcutting is often left to seek its own level of equilibrium, but
locally equilibrium can be readily maintained and or managed by the use of weirs or check dams
or sandstone outcrops. In areas of constructed channels, such as the lower reach, which may
include the removal of the drop structure at .Highway 580, measures for channel stabilization,
such as have been discussed above, may be required by Zone 7.
25
The City of Dublin requires dedication of land and improvements along both sides of stream
corridors as a condition of subdivision approval. Joint use of the stream corridor for recreation
and flood control can be compatible, as discussed in Zone 7's Arroyo Management Plan. The
minimum setback along open water~ourses, which may be enlarged at the discretion of the
Director of Public Works, is described in Section 32 of the Ordinance No. 52-87 Establishing
Requirements for Protection ofWaterfQurses. It specifies that in the case of existing channels
where the 100 year design flood can be fully contained, there will be a 20 foot minimum setback
beyond the top' of bank 0":", if the bank is steeper than 2: 1, it shall be 20 feet beyond the
hypothetical top of bank where a 2:1 slope beginning at the bottom of the bank intersects the
surface above the top of bank. In this situation, such as frequently occurs in the uppermost reach
of Tassajara Creek, where the channel is approximately 50 feet deep, and the bank nearly
vertical, the setback would be approximately 120 feet from the top of bank. Figure I shows how
this looks schematically, in particular in cro.ss-section. In other circumstances, generally not
present in the middle and upper reaches, alternative setback criteria are applied as described in
the restoration guidelines section on planning and as shown in Figures 3a, 3b, 4 and 5. Note that
in any circumstance, setbacks are required to be outside of designated floodways. Zone 7 has the
same minimum setback requirements as the City Ordinance, however has found a wider setback
of 30 feet to be more suitable.
The minimum setback rules are general rules which likely would be altered where prevailing
hydrologic conditions warrant a different approach. The key circumstance on Tassajara Creek is
in the upper reach where established looping channel patterns predictably will, over time,
migrate downstream, removing the earth which is within the meander loop. In this situation,
setbacks from the top of bank will vary in width to accommodate the future movement. A more
gentle slope than the 2:1 slope as stated in the City Ordinance No. 52-87 is probably appropriate,
considering the tendency of mefulders to migrate; there is good local precedence for required
setbacks to be calculated on the basis of slopes of 2.5: 1 or 3: 1. Setbacks should be evaluated and
determined by a qualified registered professional, taking into consideration all hydrologic issues
raised in this document. Geotechnical studies may be a part of such an evaluation. Due to the
serious liability related to potentially inadequate setbacks along Tassajara Creek, the City of
Dublin should retain their own hydrology consultant to evaluate any hydrologic studies. Figure 1
shows a hypothetical example of the type of a 2: 1 setback advisable under such circumstances.
However, a much greater setback may be prudent. Under some circumstances, Zone 7 supports
using more gentle slopes of 2.5: 1 or 3: 1. By ascertaining the setback distance from the extreme
outlying points of the meanders, stream channel, and top of bank, these points can be connected
to defIne a corridor which probably provides a reasonable hydrologic setback. It should be noted
that the topographic maps which Balance Hydrologics had available were inadequate for
determining setbacks or other hydrologic uses, however the maps were adequate for the level of
analysis required for development of the guidelines. The maps provided to Balance have five
foot contours in roughly the northern 60% of the channel, two foot contours in the middle
ponion, and one foot contours in the southern portion. A much more detailed and accurate map
should be developed. .
26
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Edge of Setback ................ ~
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Main Channel .11.11.. .:
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Top of Streambank
100 FT
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Figure 1
Setback at 2:1 minimum
Cross-Section Showing Hydrologic / Structural Setback at Meander
Extreme, thus Establishing a Minimum Limit for the Corridor Setback
HYPOTHETICAL EXAMPLE OF SETBACKS
NECESSARY_ TO ACCOUNT FOR THE FUTURE
MIGRA TION OF MEANDERS
.
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~ J'
3;0
The setbacks will result in different corridor widths for different reaches of Tassajara Creek. If
Tassajara Creek is left in its natural state, it is likely that the average width of the Tassajara
Creek corridor in the upper reach, from the East Bay Regional Park staging area to the County
line, will be 450 to 650 feet since this is the widest, deepest, and probably the most mobile part
of the channel. It may even be wider. when tributary setbacks are included. In general, the
corridor will be widest to the north, tQ.ward the County line. Substantial setbacks seem indicated
to protect structures and improvements from bank retreat and channel migration. The setbacks
are also relatively greater than in other reaches because the channel is deeper.
Alternatively, the applicant may propose to stabilize sections in the upper reach to reduce
hydrologic setbacks. However, engineering solutions in this reach could trigger the rigorous
lumy Corps of Engineers' Individual Permit. Should an engineering alternative be proposed, it
should receive close review and comment from the City of Dublin, Zone 7, Army Corps of
Engineers and California Department of Fis.h and Game. An engineering alternative should be
reviewed for the potential to trigger a transformation of the creek channel, which may be
e\1l1sive. An analysis of the creek channel by the applicant's consultant (Harvey and Associates
and MacKay and Somps) showed 100 foot setbacks in the upper reach, based on biological not
hydrological criteria.
In the middle and lower reaches, from the staging area to Highway 580, it is likely that the
average corridor width will be 250 to 400 feet, again, probably wider in the upper or northern
parts. Further hydrologic studies may show that even wider corridors are needed. Setbacks are
also discussed in restoration guidelines sections for planning.
4.7 Reclaimed Water
The use of reclaimed water for irrigation of landscaping or establishing riparian vegetation
\\~thin the study area would be of regional significance. Although the use of reclaimed water is
encouraged as.an import:mt part of water pollution control and water conservation through the
Clean Water Act and the Porter-Cologne Act, substantial safeguards for public health and the
protection of surface and groundwater are in place. In particular, the California Department of
Health Services and Regional Water Quality Control Board have established regulations for
public health and water quality protection in the event of the use of reclaimed water.
The protection is partially administered locally by Zone 7 of the Alameda County Flood Control
and Water Conservation District which holds ajoint-water-reuse requirements permit (master
permit) with Dublin San Ramon Services District and the City of Livermore. In particular, their
concern is with the effects of salt loading on the Li vermore-Amador Valley aquifer. the Niles
Cone Ala....'TIeda County Water District groundwater basin, local aquifers, and the surface waters.
Zone 7 is also responsible for upholding the Regional Water Quality Control Board's
nondegradation policy and for avoiding impacts on R\VQCB-designated beneficial uses, as set
forth in the Basin Plan. The R WQCB is also a necessary contact since they have wide ranging
water quality responsibilities. The quality of the reclaimed wastewater to be applied is critical in
28
defining restrictions on its use. Supplemental technical studies and monitoring may be required .
by the agencies to ascertain the likely and actual impacts of the wastewater application on ground
and surface waters. However, a major regional study is currently underway by Zone 7, which
may obviate this need. In the interim, Zone 7 recommends that irrigation systems should be
designed to be easily switched to recIaimedwater when such becomes an accepted policy.
4.8 Hydrology and Hydraulics Reference Bibliography - Tassajara Creek, Alameda County
ABAG. 1980. Manual of standards for surface runoff control measures. Multipaged.
Alameda County Flood Control and Water Conservation District, Revegetation Program. 1983.
Revegetation manual. Multipaged.
Alameda County Public Works Age!lcy. 1987. Hydrology and hydraulics criteria summalY for
western Alameda County. 55 pp.
Arcement, G.J.; Schneider, V.R. 1989. Guidefor selecting Manning's roughness coefficients
for natural chc:nnels and flood plains. U.S. Geological Survey Water Supply Paper 2339. 38 pp.
Barnes, H.H., Jr. 1967. Roughness characteristics of natural channels. U.S. Geological Survey
Water Supply Paper 1849. 213 pp.
.
Brian Kangas Foulk, Consulting Engineers., 1994, October 24. Dublin. Blueprint with map and
HEC-2 cross-sections, Tassajara Creek from 1-580 to above Gleason Road. Redwood City:
Brian Kangas Foulk, Consulting Engineers..
Brian Kangas Foulk, Consulting Engineers. Santa Rita Drainage Master Plan. 1995, October.
Redwood City: Brian Kangas Foulk, Consulting Engineers. 89 pp. plus appendices.
Brown & Caldwell. 1985, August San Ramon Valley Reclamation Project: primary impact and
project report. Prepared for Dublin San Ramon Services District, East Bay Municipal Utility
District, City of Pleasant on, and the City of Livermore. 2 volumes.
Brown & Caldwell. 1992, May. Livermore-Amador Valley water recycling study. Prepared for
Zone 7 of the Alameda County Flood Control and Water Conservation District, Dublin San
Ramon Services District, and the City of Livermore.
California Department of Water Resources. 1964. Alameda Creek watershed above Niles:
chemical quality of surface water, waste discharges, and ground water. 122 pp. plus
appendices.
.
29
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.
9~
California Department of Water Resources. 1974. Livermore and Sunol Valleys: evaluation of
ground water resources. Sacramento: California Department of Water Resources. Bulletin 118-
2.
California Regional Water Quality Control Board - San Francisco Region. 1991. Water quality
control plan - San Francisco Bay Regimz.
California Storm-Water Quality Task Force. 1993. California storm-water best management
practice handbooks. 3 handbooks plus appendices.
CH2MHILL. 1992, January 27. Memorandum: Hydrology and hydraulics for bridge crossing
ofTassajara Creek by two-land access road (easterly extension of Dublin Blvd.). Includes HEC-
1 and HEC-2 calculations.
Chow, V.T. Open channel hydraulics.
City of Dublin. 1987, November. Ordinance No. 52-87. An ordinance of the City of Dublin
establishing requirements for protection of watercourses. 12 pp.
City of Dublin. 1992, September 14 (revised). City of Dublin General Plan. Mulitpaged.
Dibblee, T.W., Jr. 1980. Preliminary geologic map of the Livermore quadrangle, Alameda and
Contra Costa Counties, California. U.S. Geological Survey Open File Report 80-533. Scale
1 :24,000.
Dunne, Thomas; Leopold, Luna B. 1978. Water in environmental planning. San Francisco:
W.H. Freeman and Cempany. 818 pp.
EIP Associates. 1992, January 31. Long-range wastewater management plan for the Liver-
Amador Valley, draft subsequent environmental impact report.
Federal Emergency Management Agency (FEM.t\). Flood insurance rate map, Alameda County,
California (unincorporated areas). Panel 115 (revised Feb. 19,1986) and panel 120 (April 15,
1981). Prepared by Kennedy/Jenks/Chilton.
Feth, J.B. 1961. Effects of rainfall and geology on the chemical composition of water in coastal
streams of California. U. S. Geological Survey Professional Paper 424-B. Pp. B-202 - B-204.
Glass, R.L. 1981. Ground-water resources of the Tassajara area, Contra Costa County,
California, a reconnaissance report. U. S. Geological Survey \Vater Resources Investigations
Open File Report 81-. 62 pp.
30
Holmes, Daniel 0.; Hecht, Barry. 1992. Flood hazards and control, alternativesfor portions of
Tassajara and Alamo Valleys, Contra Costa County. Berkeley: Balance Hydrologics, Inc., .
project number 9231. Prepared for Tassajara Valley Property Owners Association. Includes
HEC-l and HEC-2 analyses for area immediately upstream of Dublin Specific Plan area. 30 pp.
Holmes, Daniel 0.; Hecht, Barry. 19W, June. Tassajara Valley: approaches to hydrologic
concerns. Berkeley: Balance Hydrologics, Inc., project number 9251. Prepared for Tassajara
Valley Property Owners Association. 19 pp.
Holmes, Daniel 0.; Knudsen, Keith; Hecht, Barry. 1993, September. Quality of storm-water
runoffin Tassajara and Alamo Creeks, Contra Costa and Alameda Counties, California: 1993
baseline report. Berkeley: Balance Hydrologics, Inc., project number 9251.06. Prepared for
Tassajara Valley Property Owners Association. 26 pp.
Kent Watson & Associates. 1985. Arroyo Management Plan. San Francisco: Kent Watson &
Associates. Prepared for Zone 7, Alameda County Flood Control and Water Conservation
District. 23 pp.
Leopold, Luna R; Wolman, M. Gordon; Miller, John P. 1964. Fluvial processes in
geomorphology. San Francisco: W.H. Freeman and Company. 522 pp.
Pettygrove, G.S.; Davenport, D.C.; Asano, T. 1984. Introduction: California's reclaimed .
municipal wasterwater resource. This is chapter 1 in Irrigation with reClaimed municipal
wastewater - a guidance manual, Pettygrove, G.S. and Asano, Too, editors. Sacramento:
California State Water Resources Control Board. Report 84-1.
Rantz, S.E.--1974. Mean annual runoffin the San Francisco Bay Region: California 1931-70.
U.S. Geological Survey. Field Studies Map MF-613.
Soil Conservation Service, U.S.D.A. 1966. Soil Survey, Alameda Area, California. 95 pp. plus
plates.
U.S. Environmental Protection AgeI?cy, Office of Water. 1993. Guidance specifying
management measures for sources of nonpoint pollution in coastal waters. Multipaged.
U.S. Geological Survey. 1971, November 24. Suggested criteria for hydrologic design of storm-
drainage facili~ies in the San Francisco Bay Region, California. Open File Report.
u.S. Geological Survey. 1977, June. Magnitude andfrequency offloods in California. WRI
77-21.
.
31
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.
.
.
ID
u.s. Geological Survey. 1915-1930; 1979-1983. Tassajara Creek gaging records for stations
near 1-580. Station numbers 11-1750 and 111763000, respectively.
Wallace Roberts & Todd. 1994, January 7. Final Eastern Dublin Specific Plan. Prepared for
the City of Dublin Planning Department. San Francisco: Wallace Roberts & Todd. 168 pp. plus
appendices.
WeIch, L.E. 1977. Soil survey of Contra Costa County, California. 125 pp. plus plates.
'White, Chris; ?echt, Barry (CEG); Holmes, Daniel O. 1994, May. Regulatory and resource
protection considerations of a proposed treated effluent irrigation program for portions of the
Tassajara and Alamo Valleys, Contra Costa County, California. Berkeley: Balance
Hydrologics, Inc. Prepared for Tassajara Valley Property Owners Association. 33 pp. plus
tables and figures. Unpublished.
Woodward-Clyde Consultants. 1991. Alameda County urban runoff clean water program loads
assessment summGlY report. Submitted to Alameda County Flood Control and Water
Conservation District. (in association with Kinetic Laboratories Inc.).
Zone 7, Alameda County Flood Control and \Vater Conservation District. 1959. File No. FC
300. Drainage area map.
Zone 7, Alameda County Flood Control and \Vater Conservation District. 1990, March
(updated). Flood control base map, Zone 7 owned and maintainedfacilities. Sheet FN, File No.
FC. Scale 1 :2,000.
Zone 7, Alameda County Flood Control and Vlater Conservation District. 1991, April. Urban
li'Gter management plan update for Zone 7 of Alameda County Flood Control and Water
Conservation District, Dublin San Ramon Services District, City of Livermore, City of
Pleasanton.
Zone 7, Alameda County Flood Control and Water Conservation District. 1995, July 20 and '
September 1. Letters to Brian Kangas Foulk concerning Tassajara Creek improvements, Gleason
Road to I-580 Freeway.
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RESTORATION GUIDELINES: PLANNING
.
LEGEND:
r ' . I RESIDENTIAL
~ COMMERCIAL
lmIffi) OFFICE I INDUSTRIAL I PUBLIC SEMI. PUBLIC
I::-~~~:':<"- '1 PARKS
II OPEN SPACE
CJ SCHOOLS
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REGIONAL TRAIL!
MAINTENANCE ROAD
/
a
NOT TO .CAL~
Lower Reach
Middle Reach
Upper Reach
1I~
CORRIDOR PLAN AREA:
Tassajara Creek
Figure 2
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5.0 RESTORATION GUIDELINES: PLANNING
5.1 Channel Cross Section and Stream Setbacks
Tnree reaches of Tassajara Creek have been identified for planning purposes: lower reach
(Highway 580 to Gleason Road), middle reach (Gleason Road up to and including the East Bay
Regional Park District staging area), and upper reach (East Bay Regional Park District staging
area to the County line). Figure 2 shows the' Tassajara Stream Corridor Plan Area, including the
three reaches, proposed land uses, major road crossings, setbacks and the regional trail
alignment.
The hydrological setbacks are described in detail in hydrology restoration guidelines for channel
stability and erosivity, setbacks. Setbacks for tributaries to Tassajara Creek and sensitive habitat
features, such as seeps and aquatic sites are discussed in restoration guidelines section for creek
setbacks and buffer configuration.
The lower reach was divided into tw.o subreaches: Subreach 1 extends from 1-580 to Dublin
boulevard, and Subreach 2 extends from Dublin Boulevard to Gleason Road. The proposed
conceptual cross section for the lower reach (Figures 3a and 3b) establishes three primary zones
or treatments within the stream corridor: 1) the creek channel (the incised or graded portion of
the existing stream corricbr that carries lower flows and supports riparian vegetation 2) the flood
plain terrace or the flood control channel (the area outside the creek channel and within the
Q100), and 3) the structure setback (above the Q100). The combined width of the flood plain
terrace and the structure setback should be a minimum of 100 feet on either side ofthe incised or
graded channel to comply with California Department of Fish and Game setback standards,
unless an exception is negotiated with the Department. This minimum setback is referred to as
the wildlife setback in Figures 1, 3a, 3b, 4 and 5.
The proposed-conceptual cross section for the middle reach (Figure 4), between Gleason Road up
to and including the East Bay Regional Park District staging area establishes three primary zones
or treatments \vithin the stream corridor: 1) the existing creek channel that supports riparian
vegetation (which in some sections contains the Q100 and in other sections does not), 2) the
flood plain terrace (the area of the existing stream corridor above the existing creek channel, or
the area graded to accommodate the flood flows below the Q1 00), and 3) the structure setback
(above the Q 100). The combined width of the flood plain terrace and the structure setback should
be a minimum of 100 feet on either side of the existing channel to comply with California
Department ofFish and Game standards, unless an exception is negotiated with the Department.
The northerly portions of the middle reach are expected to contain the 100 year flood flows,
while the southerly portions may not. A detailed hydrological analysis based on cross sections
",ill confirm existing conditions and will identify requirements to grade the flood plain terrace to
accommodate flood flows.
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t Optional landscape plantings
fandscape Structure
easement I setback Flood control channel
(20' minF (30' m;n (0100)
I Requffed I
restoration Plantingl
Existing
creek channel Flood control channel
varies (0100)
.
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. '. '~.. 1
: Optional landscape planfings
structure Landscape
I setback I easement
(30' min) (20' minJf
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1
Wildlife setback-
(100' min.)
I lo:X~~'1;:nk 1 Excaval. for flood
_ _ _ _ _ _~I,,~conlr:;;;~-' /~
Y,v ",'If;;' ~II--
W/7$// p. Maintenance road
1_ J1 .,1 tY Wlldllf. ..fback'
~ (100' min.)
stream Corridor
width lIaries
t
/1-
'Measured from existing lop of bank
TYPICAL CROSS SECTION
LOWER REACH
SUBREACH 1 - 1580 TO DUBLIN
NTS
Tassajara Creek
Figure 3a
Optional landscape plantings
Required
restoration planting
Optional landscape plantings
Flood plain terrace
Creek channel
vanes
Flood plain terrace
Structure
setback
(30' min)
Trail/roa
right-of-way
I
, '
Excavate for I Top of bank ~
flood plain terrace
as required Excavate for flood plain
15 I I terrace as required
year eve;
______2 j,; 0 zz;<
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=11'
\ :':;77-::-
Regional trail/
maintenance road
see fig. 9
Existing grad9
maintenance road
see fig. 10
1
Wildlife s9tback-
(100' min.)
Wildlife setback-
(100' min.)
1
Stream Corridor
width lIaries
TYPICAL CROSS SECTION
LOWER'REACH
SUBREACH 2 - DUBLIN TO GLEASON
NTS
-Measured from existing lop of bank
Tassajara Creek
Figure 3b
40
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.
Existing
flood plain terrace
Creek channel
varies
Flood plain lerrace
Local Irail)
maintenance road
see fig. 10
r Exlsflng
lop of bank
"Q" varies
Excavate for flood plain
~.rrac:;;;;;;;
Regi:~:1 Irail/)
maintenance road
see fig. 9
Existing grade
Wildlife sefback
(100' min.)
;{-
l'
Wildlife setback
(100' min.)
Stream Corridor
------------ ---
width varies
TYPICAL CROSS SECTION
MIDDLE REACH
NTS
Tassajara Creelc
Figure 4
" '/1:.
Hydrologic / Structural
setback
varies
~
Regional trail I
maintenance road
see fig.. 9
Wildlife setback
(tOO'minl
"11
.
Existing creek channel
varies
Existing
top of bank
Existing
top of bank ~
\
"
Stream Corridor
width varies
TYPICAL CROSS SECTION
UPPER REACH
NTS
Tassajara Creek
Figure 5
.
Hydrologic / Structural
setback
varies
4
l.ocal trail /
see fig. 11
Wildlife setback
{100'min}
.
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.
1..1 ([
I D
The structure setback, described for the lower and middle reaches, should be a minimum of thirty
feet in width a!ong both sides of the creek outside the flood plain terrace. The trails and
maintenance access right-of-way should be concentrated within this setback. Wider structure
setbacks should be encouraged. Landscaping and vegetation of adjacent developments or within
the structure setback should create a soft edge to enhance and enlarge the trails and maintenance
corridor.
The proposed conceptual cross section for the upper reach (Figure 5), above the East Bay
Regional Park District staging area to the County line establishes two primary zones or
treatments within the stream corridor: 1) the existing creek channel that readily contains the 100
year flood flows and supports riparian vegetation at lower elevations, and 2) the hydrological-
wildlife-structural setback outside the existing creek channel. The hydrological setback
incorporates structural and slope bank failure considerations for the character of this portion of
the channel. To comply vvith California Department ofFish and Game standards, the wildlife
setback is a minimum of 100 feet from top of the existing channel banks, unless an exception is
negotiated with the Department. The wildlife and hydrological setbacks will overlap and the
greater of the two controls the final Qutside edge of the stream corridor.
5.2 Trails and Maintenance Roads
Consistent with the Specific Plan, the trails and maintenance roads should be combined and
located to establish a stn:.an1 corridor system that provides multi-purpose open space corridors
capable of accommodating both wildlife movement and pedestrian circulation. Trails and
maintenance road planning should encourage a continuous open space network that integrates
large natural open space areas, the stream corridors, and developed parks and recreation areas.
This trail and open space network should then link regional and local trails, employment centers,
residential areas, schools, parks, commercial centers, neighborhood parks and open space. The
trail system should accommodate pedestrian~, bicyclists and equestrians, in addition to the
maintenance vehicles.
Local trails and local trails/maintenance roads are shov,1Il on figures, however under the Specific
Plan, the City of Dublin is only required to provide for a regional trail and connections to that
trail. Figures 3-5 show typical cross sections and Figures 6-8 show plan view concepts for the
lower, middle and upper reaches ofTassajara Creek. Figures 9-11 show the trail standards for the
regional traiVrnaintenance road, local trail/maintenance road and local trail.
Tributaries should be improved with local trails designed to connect to the regional trail and
provide convenient pedestrian and bicycle connections between neighborhoods and otber
destinations within the plan area. Local trails sbould utilize the tributary as an open space
corridor connection.
39
The trails and maintenance roads should be combined to provide for safe pedestrian and two-way
bicycle use, and adequate maintenance access. Public safety issues should be mitigated in the .
upper reach, where there are steep and high creek banks. Mitigation should discourage bank
access and could include: locating the trail at the outside of the established setback, mitigating
erosion from surface drainage above the creek banks, strategically placed fencing, proper
signage, removal of large debris or rubble, reducing cattle watering in the creek, and localized
repairs of soil sinking (piping).
The trail system should be evaluated for compliance with American Disabilities Act (ADA).
5.2.1 Regional TrailIMaintenance Road Standard
In response to the trail and road requirements of East Bay Regional Park District, Zone 7 and the
City of Dublin, a regional trail should be developed along one side ofTassajara Creek, from the
new Bart station at Dublin Boulevard to the County line. The removal of the drop structure at 1-
580 will provide for future trail connections into Pleasanton.
These guidelines for trails and roads combine standards from all three agencies, with an
emphasis on the stricter City's Trails and Bikeway standards in the City of Dublin Parks and
Recreation Master Plan. The regional trail should accommodate pedestrians, bicyclists and
equestrians. The regional trail should be concentrated within the thirty foot minimum structure
setback. The combination regional trail/maintenance road should consist of twelve feet of paved
pathway with a six inch compacted aggregate base, and with two rocked shoulders, one two feet .
"vide and the other four feet (Figure 9). A twenty foot right-of-way should be maintained clear
for Zone 7 maintenance access. The twelve feet paved and six feet of rock shoulders will exceed
the fifteen foot all-weather surface requirement of Zone 7. This paved trail will serve as a Class I
Bikeway and equestrians may safely use the four foot rocked shoulder. Because of its width, the
trail/road may be used jointly for fire maintenance.
The regional trail and maintenance road may occasionally meander out of the thirty foot structure
setback and into the flood plain terrace within the wildlife setback, but should primarily be
located in the established right-of-way to maximize public safety, enhance access for police
patrols, minimize wildlife disturbance, and minimize trail maintenance due to erosion or
siltation.
Adequate and secure bicycle parking will encourage bicycle use. Parking should be located at
shopping centers, public transit access points, park and ride lots, schools, and employment
centers.
The regional trail that runs parallel to Tassajara Creek may be interrupted at certain locations as
dictated by specific site conditions, however ingress and egress to the trail system should be
provided at these points of interruption. Adequate maintenance vehicle access should also be
provided at these points.
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40
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Access should be controlled through the use ofbollards, gates or similar systems acceptable to
the emergency response agencies, to prohibit undesired vehicle access, while allowing
maintenance and emergency vehicle access and encouraging bicycle use of the regional trail.
Access points should be provided at multiple points, at approximately 1,300 foot intervals along
the stream corridor. Comrolled access for maintenance vehicles should be provided through
adjacent development, such as parkil1g areas and residential streets. 'Where a street parallels the
creek corridor, separate access is not necessary.
In addition, where a street parallels the creek corridor, the sidewalk may be eliminated in favor of
pedestrian and bicycle use of the regional trail. This creates a softer edge of the development
against the stream corridor.
41
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NOT TO SCALE
OFFICE / INDUSTRIAL
IJ
Regional trail crosses road at grade
Local trail crossing with roadway
Provide controlled maintenance vehicle
access at 1300 foot intervals
PARK
Local trail connections and
staging area through park
Regional trail I Maintenance road
Transit Spine
~\--r\~ Local trail crossin I g with roadway
RESIDENTIAL "
. RESIDENTIAL
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1. \
.
COMMERCIAL
Design to take advantage
of creekside setting
--.------
Local trail crossing with roadway
I I I I
\ { Enyouragf singl'i loaded streets J
'\ cur-de-sacs or loop str~ts that
. open onto creek __
~ DUBLIN BLVD.
}
i
\ Local trail I Maintenance road
BART ~.
Local trail crosses road under bridge
OFFICE / INDUSTRIAL
Design to take advantage
of creekside setting
Gravel road I Maintenance road
Provision to
LEGEND:
'.580 .
FREEWAY
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Local trail / Maintenance road
........... ~. ............ -.....................
Local trail
---------------
Gravel road / Maintenance road'
_1_1_1_1_1_
.
PLAN VIEW CONCEPT
LOWER REACH
Tassajara Creek
Figure 6
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PUBLIC / SEMI - PUBLIC
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Regional trail and
maintenance vehicle crossing
----
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Local trail linking jr. high school with
reSlde]tial and ne;ghborhood park
SCHOOL
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Encourage single loaded streets,
cul-de-sacs or loop streets
Maintenance road that open onto creek
may be interrupted. /j' ~ESfDENTfAL
~ .J.: Local trail /
. // Maintenance road
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Regional trail/Maintenance road
ROAD"
LEGEND:
PARK
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Local trail! Maintenance road
_.~._.~.1ftH
Local trail
---------------
PLAN VIEW CONCEPT
MIDDLE REACH
Tassajara Creek
Figure 7
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NOT TO SCALE
OPEN SPACE
Local trail
RESIDENTIAL
,
,
.
Local trail crossing with roadway
Q
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Encourage single loaded streets 1
cul-de-sacs or loop streets that
open onto creek
_ Regional trail/Maintenance road
63
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PLAN VIEW CONCEPT
UPPER REACH
Tassajara Creek
Figure 8
LEGEND:
Regional frail / Maintenance road
Local trail
------~---------
.
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---
.
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6" aggregate base
4' mln
Re lonal. trail
12' wide J paved
18' wide all -weather surface
30' structure sefback
REGIONAL TRAIL/ MAINTENANCE ROAD
Tassajara Creek
Rgure 9
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TassaJara Creek channel
!.
6Haggregate base
Local trail . 5' gravel
8' wide, paved
15' wide all -weather surface
15' minimum
set b k
from top of bank
LOCAL TRAIL/ MAINTENANCE ROAD
Tassajara Creek
Figure 10
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Local frail
8' wide, paved
12' wide
all-weather surface
25' easement
30' where development occurs both sides
LOCAL TRAIL
NTS
Tassajara Creek.
Figure 11
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5,2.2 Local TraiJlMaintenance Road. Standard
Consistent with the Specific Plan and requirements of East Bay Regional Park District, Zone 7,
and the City of Dublin, local trails are required to provide connections between residential
neighborhoods and destinations, such as the regional trail access points, employment centers,
commercial ar~as, neighborhood parks, schools and open space. The local trails should be
designed to serve pedestrians and bicycles.
These guidelines for local trails and roads combine standards from all three agencies, with an
emphasis on the stricter City's Trails and Bikeway standards in the City of Dublin Parks and
Recreation Master Plan. The local trail sho~ld accommodate pedestrians and bicyclists within a
twenty five or thirty foot easement, depending upon adjacent land uses. The combination local
trail/road should consist of eight feet of paved pathway with six inches of compacted aggregate
base, and with two rocked shoulders, two foot on either side of the trail (Figure 11).
Where local trails are combined with the maintenance road that is required by Zone 7. This local
trail/maintenance road should have the fifteen feet of gravel all-weather surface required by Zone
7 on a six inch compacted aggregate base. Eight feet of this surface shall be paved, leaving seven
feet in rocked shoulders. A twenty foot right-of-way should be maintained clear for Zone 7
(Figure 10).
The local trails that run parallel to Tassajara Creek may be interrupted at certain locations as
dictated by specific site conditions, however ingress and egress to the trail system should be
provided at these points of interruption. Adequate maintenance vehicle access should also be
provided at these points.
Access to the local trails should be controlled through the use ofbollards, gates, fences or similar
systems acceptable to the emergency response agencies to prohibit undesired vehicle access,
while allowing for plaintenance and emergency vehicle access and encouraging bicycle use of
the local trails. In situations where a maintenance road will not be used as a local trail, fences
may be necessary to control undesired access. Access points should be provided at multiple
points, sufficient to link local pedestrians and bicycles to the regional trail and other significant
destinations, such as schools, parks, the regional trail and shopping and adjacent land uses such
as residential areas. Local trails should provide east/west connections from adjacent land uses
and other destinations to the regional trail. Controlled access for maintenance vehicles should be
provided through adjacent development, such as parks, parking areas and residential streets at
multiple points approximately 1,300 feet apart along the stream corridor. Maintenance access
will be facilitated where streets parallel the creek corridor.
In addition, where a street parallels the creek corridor, the sidewalk may be eliminated with the
local trail serving as its substitute as long as the local trail is sited outside the flood plain terrace
or 'within the structure setback. This will create a softer edge to development against the stream
corridor.
48
5.2.3 Gravel Maintenance Road Standard
Where no regional or local trail is proposed, and Zone 7 will require maintenance access, gravel .
roads on both sides of the creek should be provided as in Subreach 1 in the lower reach (Figure
3a). Zone 7 requires a fifteen foot all-weather surface with a six inch compacted aggregate base,
both preferably located above the QI00. If this is not practical, Zone 7 may accept one lower
maintenance road above the Q 15, pa~e_d in asphalt concrete or concrete. Controlled access to the
maintenance roads at these locations should be provided through adjacent development, such as
parking areas and streets. Ramps to the low flow channel may also be necessary and should be
evaluated on a case-by-case basis. Where Zone 7 maintenance roads will not be required, a
combination trail/road or trail without road should be provided as discussed above.
5.2.4 Trail Standards by Reach of Tassajara Creek
Trail standards should reflect surrounding conditions and needs, and accordingly, have been
developed by creek reach.
Lower Reach ofTassajara Creek The lower reach of Tassajara Creek is located between
Highway 580 and Gleason Road. Consistent with East Bay Regional Park District requirements,
the regional trail/maintenance road should be located on the east side, while the local
trail/maintenance road should be located on the west side of Tassajara Creek. As expressed by
East Bay Regional Park District, the regional trail should be located above the flood plain
terrace, within the structure setback, to facilitate vehicle patrols, maximize public safety,
minimize wildlife disturbance and reduce trail maintenance requirements following flood events. .
The regional and local trails could meander within the wildlife setback to create interest.
The local trail/road should be located above the flood plain terrace, above the Q 100 in this reach.
A regional trail connection from the East Dublin BARTlIron Horse trail to Tassajara Creek along
the north side of Dublin Boulevard, and a provision for a potential trail connection under 1-580 to
Pleasanton through County property should be made.
Where trails are not planned in this reach, gravel maintenance roads should be provided on either
side of the creek according to Zone 7 maintenance access requirements (Subreach 1). These
maintenance roads could at some point in the future be converted to a trail to facilitate the future
Pleasanton connection.
The regional trail and maintenance road may occasionally meander out of the structure setback
and onto the flood plain terrace within the wildlife setback, but should primarily be located in the
established right-of-way to maximize public safety, enhance access for police patrols, minimize
wildlife disturbance, and minimize trail maintenance due to erosion or siltation.
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Trail connections across Gleason Road should be made at grade. Trail crossings at Dublin should
be made under the Dublin Boulevard bridge, with an alternative route for at grade crossings in
wet weather conditions.
Middle Reach ofTassajara Creek In the middle reach of Tassajara Creek, between Gleason
Road up to and including the East Bay Regional Park District staging area, the regional trail
should connect with the trail on the lower reach at Dublin Boulevard and continue on the eastern
side of Tassajara Creek until it reaches the staging area. As with the lower reach, the regional
trail should be located within the structure setback above the flood plain terrace. The regional
and local trails could meander within the wildlife setback to create interest.
The local trail/maintenance road should be located on the west side of the creek, v,rithin the flood
plain terrace. The maintenance road may be' interrupted by existing site constraints. The
eucalyptus grove above Gleason Road will prohibit construction of a road. Where the trail is
interrupted, controlled maintenance access should be provided with a vehicle turnaround. The
local trail however should continue uninterrupted along the stream corridor.
The regional trail and maintenance road may occasionally meander out of the structure setback
and into the flood plain terrace within the wildlife setback, but should primarily be located in the
established right-of-way to maximize public safety, enhance access for police patrols, minimize
wildlife disturbance, minimize trail maintenance due to erosion or siltation.
Upper Reach ofTassajara Creek In the upper reach, from the East Bay Regional Park District
staging area to the County line, the regional trail/maintenance road should cross Tassajara Creek
at the staging area, and continue along the western side of the creek in the setback from the top of
the Tassajara Creek barue. The local trail from the middle reach merges with the regional trail at
the staging area. In the upper reach a local trail should be located on the eastern side of the creek
within the setback area. Both the regional and local trails in the upper reach may occur within the
wildlife setback. The local trail should cross the tributary channel in cOrUunction with the
proposed street.
5.2.5 Staging Areas and Trail Heads for Hiking and Equestrian Trails
The Specific Plan provides a primary staging area in conjunction with a school or a park.
Equestrian uses should be compatible with other staging area activities. Equestrian access should
continue to be provided at the existing East Bay Regional Park District staging area, The existing
regional staging area should be enhanced in accordance with standards for staging areas and trail
heads in the City of Dublin Parks and Recreation Master Plan. The primary staging area should
accommodate horse trailers, drinking water, rest rooms, telephone, hitching posts, a rest area
v.rith tables, access for emergency vehicles, fire hydrants, trash receptacles, lighting, gates,
signing and fences. Loading areas for horses should be buffered from Tassajara Road, to create a
safe environment for handling horses.
50
Trail access points should be provided at connections to the regional trail throughout the plan
area, including park and school locations. Access points should have at a minimum the lesser
improvements consisting of parking, drinking water and trash receptacles. Other trail access
points along the regional trail should be treated as enhanced trail access points and should
receive parking, drinking water, trash receptacles, rest rooms, lighting, and telephone. Drinking
water should be provided at frequent intervals along the trail.
.
5.3 Stream Crossings
Creek crossings should be sited so as to provide convenient access to destination areas, such as
parks, schools, the commercial center and other open space, and to link the local and regional
trails. Creek crossings should be designed and landscaped to emphasize creek character, establish
view corridors and screen wildlife from concentrated human use.
Where roadway crossings are combi?ed with trail crossings, the trail user should be separated
from the traffic by an appropriate barrier for safety considerations, such as raised sidewalks,
raised curbs or concrete barriers.
There should ~e a creek ~rossing approximately every 2,000 feet along the creek corridor to
facilitate pedestrian access to the trails. In each of the three reaches ofTassajara Creek, there will
be a specified number of road crossings, therefore added pedestrian or road creek crossings will
be necessary at certain locations to link the trails with adjacent land uses. Figures 6-8 show
existing, proposed and potential stream road crossings at approximately 2,000 foot intervals, in .
the lower, middle and upper reaches ofTas~ajara Creek.
In the lower reach (Highway 580 to Gleason Road), the two road crossings and the transit spine
crossing with associated trail crossings proposed by the County will be adequate with some
modifications for public safety to meet this criterion.
In the middle reach (Gleason Road up to and including the East Bay Regional Park District
staging area) a minimum of two trail crossings should be provided to create crossings at
approximately 2,000 foot intervals. This reach is approximately 4,200 linear feet in length. The
Specific Plan shows no road crossings to access the medium density residential area on the west
side of the creek. A trail crossing should be combined with a road crossing in the middle of this
reach to access the medium density residential area on the westerly side of the creek.
Alternatively, a trail crossing could be provided at the northerly boundary of the Junior High
School site, linking the local trail from the neighborhood park site to the east of Tassajara Road.
The East Bay Regional Park District staging area, at the boundary between middle and upper
reaches has a pedestrian crossing that should remain. An additional crossing for maintenance and
emergency response vehicles should be created in the vicinity of the staging area crossing.
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The Specific Plan shows five road crossings in the upper reach (East Bay Regional Park District
staging area to, the CountY. line), however this many crossings many be infeasible given the
width of the Tassajara Creek in this reach. The reach is approximately 5,600 linear feet and a
crossing will be provided at the East Bay Regional Park District staging area, therefore a
minimum of two well-spaced crossings should be provided to adequately satisfy the trail crossing
guidelines. The local trail along the tributary to the east and north of the staging area should be
continued in a northerly direction along-the east side of the creek and should share the staging
area crossmgs.
There are seasonal crossing that are usable during low flow periods, located along Tassajara
Creek, which may serve local unmaintained access needs. These crossings however, do not meet
ADA standards, nor do they satisfy the trail and road standards described herein Additionally,
they are not usable during moderate creek flows. Therefore they may remain but should not be
included in the trails planning. Iflow flow crossings are removed, restoration of disturbed areas
is described in restoration guidelines for resource protection, restoration and mitigation.
Creek crossings should not reduce the flood capacity of the creek, but should be designed to
provide for continued trail access either above or below the crossing. Special trail sections such
as stream crossings are addressed in the City of Dublin's Parks and Recreation Master Plan.
Some existing .crossings, such as the East Bay Regional Park District crossing, should remain
with the understanding that it may wash out in very high flows and would have to be rebuilt.
Creek crossings will occur at all major road crossings ofTassajara Creek. Creek crossings should
be designed and landscaped to emphasize creek character, establish view corridors and screen
wildlife from concentrated human use.
Creek crossings should be located to minimize disturbance to the riparian vegetation in~e creek
corridor, while maximizing engineering stability. Since the meanders of Tassajara Creek will
migrate down stream over the long term, crossings should be placed above meanders where
feasible, and the very wide portions of the creek should be avoided. The creek section should be
stable, which is generally indicated by dense vegetation. Bridge construction should strive to
minimize impacts in these sections. The vegetation will also screen the crossing. Bridge design
should avoid or minimize piers or other supports in the creek channel since these are known to
catch debris in high flood flows, If piers are incorporated into a design, they should be widely
spaced to minimize catchment. An appropriate location for a creek crossing would be a narrow
and stable or vegetated section of the creek, located above a meander.
5.4 Developm~nt-Corridor Interface
The interface between proposed development and the stream corridor should be evaluated in
great detail. DevelopmeI~: abutting the stream corridor should meet several criteria including: 1)
preservation and enhancement ofthe biological values; 2) convenient corridor access; 3) street
52
layout concepts similar to those presented in Figure 12; 4) separation of wildlife and human
activities within the corridor; 5) provisions for frequent access points within each development;
and 6) enhancement of the visibility and character of the stream corridor. The stream corridor .
constitutes the major north/south open space feature of the Specific Plan area. The character of
the stream corridor should be complemented by its interface with proposed adjacent land uses.
The interface should vary with adjacent land use.
Figures 6-8 show in plan view the potential interface between the stream corridor and adjacent
development for the lower, middle and upper reaches of Tassajara Creek. Figure 12 shows three
types of road systems to create a desired development stream corridor interface. Figures 13 and
14 show typical stream corridor interfaces with commercial and residential development,
respectively.
Open space trail alignments should be coordinated with street sidewalks and bike lanes to: ensure
continuity of linkages between schools, neighborhoods, and commercial centers; achieve
convenient access from developed areas to designated open space areas and trails; and emphasize
pedestrian connections between developed and natural areas.
Creekside trails should be coordinated \vith wildlife corridor requirements and planning should
avoid development that backs directly onto the stream corridor. Residential development should
be designed to'orient to tne creek as a visual amenity. Schools and parks should be designed to
take advantage of creekside settings and educational opportunities.
Trail heads should be provided at the corridor interface with convenient vehicular, bicycle and .
pedestrian access points, such as schools and parks, and where streets abut the corridor.
The structure setback, described for the lower and middle reaches, should be a minimum of thirty
feet in wid~ along both sides of the creek outside the flood plain terrace. The trails ,and
maintenance access right-of-way should be concentrated within this setback. The thirty foot
structure setback should be widened in places to allow the regional trail to meander to create
interest. Landscaping and vegetation of adjacent developments and within the structure setback
should create a soft edge to enhance and enlarge the trails and maintenance corridor.
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LOOP STREETS
-,
-C
. RESIDENTIAL DEVELOPMENT INTERFACE NTS
Tassajara Creek
I J'
Figure 12
Stagger building setbacks
to create softer edge
"
Trail
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: Flood Plai~_ terrace J
:
. Creek channel
:
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. COMMERCIAL DEVELOPMENT INTERFACE .
WITH STREAM CORRIDOR NTS
Tassajara Creek
(pL/
Figure 13
.
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W, I I
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I --
LLJ j _j
T -- I J 1
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r Eliminate sidewalk
Y.' in favor of trail "
to soften. edge .
.
RESIDENTIAL DEVELOPMENT INTERFACE
WITH STREAM CORRIDOR
Tassajara Creek
NTS
b5
Figure 14
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In commercial and industrial zones, buildings should be staggered or offset from the creek
corridor to enlarge the apparent open space setback and soften the linear edge of the creek
corridor (Figure 13). Views from proposed commercial and office facilities as well as outdoor
areas associated with these uses should be oriented toward the stream corridor. Screening of trails
from parking lots, storage areas, trash receptacles, loading docks, and similar facilities should be
accomplished through landscaping.
Pedestrian access to this corridor can be emphasized by encouraging streets that open up on the
creek or are single loaded against the creek, giving the neighborhoods a highly valued character,
and providing convenient access to the open space and trail connections of the creek corridor
(Figure 14).
Where the stream corridor abuts neighborhood parks, the stream corridor should be integrated
into the park design and use. Active park uses should be limited to the outside of the flood plain
terrace, and passive park uses should be allowed to enter the flood plain terrace. Park uses should
be prohibited in the creek channel.
5.5 Channel Modifications and Stabilization
Channel improvements or modifications should accommodate projected flood flows and
ex1ensive revegetation, and avoid the need for periodic vegetation removal, as discussed in the
restoration guidelines for hydrology. Preservation of the creek channel, is paramount to the
preservation of the existing vegetation and wildlife corridor, consistent with the restoration goals.
The channel should be allowed to naturally revegetate, erode and meander 'within the flood plain
terrace. The preferred cross section of creek emphasizes a creek channel that supports vegetation
and a flood plain terrace to accommodate stream corridor setbacks and additional flood flows.
The flood plain terrace should be managed to support non-irrigated grasses. Landscape plantings
could be established on the flood plain terrace with permanent irrigation. Where channel
modifications are required, the channel should be shaped and graded to contours v'lith a-natural
appearance. Figures 3-5 show typical cross sections of the stream corridor for the lower, middle
and upper reaches of Tassajara Creek.
The landowner, the County of Alameda is proposing removal of the drop structure at Highway
580 and modification of the creek channel and/or flood plain terrace between Highway 580 and
Gleason Road to accommodate flood flows. In Subreach 1 a trapezoidal channel is proposed.
Modifications in Subreach 2 will be designed to preserve the natural meandering of the existing
stream. The reach of stream above the Gleason Road presents an excellent model for meandering
in this system,
Unless necessary, modifications to the creek channel of Tassajara Creek should be minimized.
Any regrading of the creek channel ofTassajara Creek should result in a natural appearance with
a gently meandering creek bottom.
57
Any regrading of the creek channel should result in varying side slopes to provide a more natural
appearance. Regrading to create a flood plain terrace above the low flow channel should be .
gently sloped, with a maximum slope of 3: 1. The wildlife setback (100 feet from top of existing
bank) may allow for a very gentle slope on the flood plain terrace.
Non-structural solutions should be used to increase channel capacity and stabilize stream banks.
Energy dissipaters and erosion control--devices should consist of natural materials, i.e., vegetation
or boulders, to increase the roughness coefficient of the channel bottom. Energy dissipaters
should be adequately engineered to handle peak flow conditions of Tassajara Creek. Detailed
hydrological analysis should determine erosive potential of various flood-stage flows. Careful
study should be made to ensure the adequacy and stability of any proposed energy dissipaters
and bioengineering devices. Bioengineering techniques are discussed in the restoration
guidelines section below for hydrolqgy, as well as resource protection, restoration and
mitigation.
Trails and maintenance access roads should be located to avoid disruption by the meandering of
Tassajara Cre~k. 'Where the trails and maintenance roads deviate from the outside edge of the
stream corridor and are sited on the flood plain terrace, adequate setback from Tassajara Creek
should be adopted to protect their long-term integrity.
Outfall structures should be designed according to official County drainage improvement
standards. Improvements can be made to th~ outfall design to screen the hard structures from trail
and bridge users. Planting in rip-rap and other hard structures is discussed in restoration
guidelines for resource protection, restoration and mitigation. Outfall structures and low flow
creek crossings that have minimal effect on the channel bottom and low flow channel are
desirable. Long-term erosion effects of these features should be considered as well. Disruption
to the wildlife corridor should be minimized.
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RESTORATION GUIDELINES: RESOURCE
PROTECTION, RESTORATION AND MITIGATION
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6.0 RESTORATION GUIDELINES: RESOURCE PROTECTION, RESTORATION AND
MITIGATION
6.1 Creek Set Backs and Buffer Configuration
A setback from the Tassajara Creek channel and its tributaries is required for biological as well as
flood control reasons. The hydrological setbacks are described in detail in hydrology restoration
guidelines for channel stability and erosivity, setbacks, Regarding biological considerations, the
California Department ofFish and Game routinely recommends a 100-foot set back from the top of
the existing banks of major creeks, such as Tassajara Creek and its major tributaries, as discussed in
the planning restoration guidelines for channel cross section and stream setbacks. Because the
riparian zone most valuable to wildlife is within the creek channel, the stream corridor cross section
required for flood control will in most cases provide the needed setback from Tassajara Creek.
Biological (wildlife) setback requirements for the tributaries vary with the site conditions,
environmental.resources, need to accommodate trails and nature of adjacent development. In
general, setbacks should be 100 feet from the existing top of bank for major tributaries and 50
feet from top of bank for minor tributaries according to California Department ofFish and Game
standards, unless an exception is negotiated with the Department. Setbacks for the minor
tributaries for which trails have been planned should be a minimum of 50 feet, with the trail sited
primarily at the outside of the buffer. For the purpose of this document, minor tributaries are
defined as grassy swales not supporting shrub and tree vegetation, and major tributaries are
defined as tributaries that are deeply incised, and support a dense canopy of shrubs and trees.
Applicant submittals should justify proposed tributary setbacks based on: flood flows, existing
vegetation, quality of habitat, bank conditions and treatments, and current and proposed land
uses. Proposed tributary setbacks should be large enough to ensure public safety, flood control,
restoration plantings and safe passage of wildlife.
-- Biological setback requirements for the major tributaries where deeply incised in the northeast~rn
portion ofthe study area should be a minimum of 100 feet from top of bank. Setbacks associated
\vith the golden eagle nest \vithin this corridor have been established in the Eastern Dublin
General Plan Amendment and Specific Plan Final ErR.
Erosion and hydrologic considerations may allow for flexibility in the biological setbacks for
tributaries. The buffer created by the setbacks on major tributaries does not need to be centered on
the creek, although equal distribution on both sides is preferred in most cases. As long as the
hydrologic setback minimum is met. the biological or wildlife setback may be arranged to
incorporate more valuable habitat on one side ofthe tributary at the expense ofless valuable habitat
on the other. Alternatively. it may be narrower than 100 feet (or 50 feet for minor tributaries) for
short stretches, if it is wider in others and its average is the required buffer area. Under no
circumstances should the buffer be less than 50 feet on one side. If creek banks are graded back to
form gentler slopes or channels are reconfigured, the 50 or 1 OO-foot setback would be calculated
from the original top of bank. Before the buffer is modified however, erosion and hydrologic
59
setback requirements must still be met. Newly configured banks should be restored with native
vegetation. Bank reconfiguration should be accompanied by specific restoration plans designed to .
improve overall wildlife values.
Setbacks from sensitive habitat areas, such as seeps, and aquatic sites for sensitive amphibian
species may require greater buffering and should be evaluated on a case-by-case basis by the City
of Dublin, California Dep<mment ofFish-and Game and U.S. Fish and Wildlife Service.
6.2 Tributaries to Tassajara Creek
There are several tributaries to Tassajara Creek in the Specific Plan Area. In general, all of the
restoration guidelines described herein apply to the treatment of the tributaries, with noted
exceptions. For the purpose of this document, minor tributaries are defined as grassy swales not
supporting shrub and tree vegetation, and major tributaries are defined as tributaries that support
shrubs and trees or are in close proximity to ponds, seeps or springs. Setbacks and buffers are
discussed in the above section.
Many of these tributaries are candidates for restoration, both habitat enhancement and mitigation.
Mitigation of sensitive aquatic habitats, such as that for the California red-legged frog and
western pond turtle may be more suitable in the tributaries than in Tassajara Creek, since flood
flows and sediment loads can thwart amphibian habitat creation.
As with Tassajara Creek plantings, the groundwater profile of the drainages must be determined .
through measurement or interpolated from vegetative indicators, in order to determine planting
zones prior to development of planting plans.
Engineering or bioengi~eering in the tributaries may be required to: dissipate energy, reduce flow
velocities at or near the streambank surface, buffer the streambank against the abrasive effect of
transported materials, induce sediment deposition, and armor banks against high flows and debris.
Because flood flows in the tributaries are less severe than in Tassajara Creek, bioengineering
techniques may be feasible alternatives to hard engineering structures.
Setback requirements for the tributaries vary with the site conditions, environmental resources,
the need to accommodate trails, and nature of adjacent development. Setbacks are discussed in
the section above entitled Creek Set Backs and Buffer Configuration.
6.3 Creek Channel and Bank Modifications
Creek channel and bank modifications are discussed in other sections. On sites where grading
modifications create large bare soil areas or result in removal of large stands of vegetation,
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revegetation according to these guidelines should occur. Where major grading and modifications
are proposed to accommodate flood .control and access along Tassajara Creek between Gleason
Road and Highway 580, restoration plantings should be required to provide channel stabilization
and wildlife habitat, subject to California Department ofFish and Game review and approval. In
.
60
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reaches of Tassajara Creek where existing native vegetation is abundant and diverse and needs
. no modification, little to no planting is anticipated.
6.4 Engineering and Bioengineering Techniques
Bioengineering is a low-tech method of construction using living plants in combination with non-
living or inorganic materials. Engineering techniques on the other hand, rely solely on inorganic
materials, or hard structures to achieve similar goals. Bioengineering within the stream corridor,
where feasible, is desirable because the plants incorporated into the engineering treatments, i.e.,
bioengineering, serve to camouflage the hard structures, provide additional stabilization and
provide habitat value. Bioengineering is used for a number of purposes including: dissipate energy,
reduce flow velocities at or near the streambank surface, buffer the streambank against the abrasive
effect of transported materials, induce sediment deposition, and armor banks against high flows and
debris. In most instances, the living p.1ants become the functioning technical component of the
system. There are site conditions that dictate hard structure solutions, but where appropriate,
bioengineering alternatives should be considered and be given preference if bioengineering can
accomplish the goals. For example, check dams constructed to check downcutting may rely on
large rock, con~rete structures or secured logs. If logs could create maintenance problems by
becoming dislodged in high flows, hard structure solutions should be used. Bioengineering
techniques are not necessarily more stable or less expensive than traditional structural engineering
solutions.
.
Possible scenarios for which engineering or bioengineering solutions should be considered include:
bridge crossings, creek low flow crossings, creek bank stabilization, trails or roads located near
stream banks, and check dams. It is critical to analyze and document the upstream and downstream
hydrologic conditions and fluvial geomorphic processes affecting the stream system before
designing appropriate engineering or bioengineering treatments. Any changes to channel hydraulics
caused by the installation of these treatments should be analyzed and documented, for appropriate
agency reVIew.
Soil compaction during the installation of bioengineering structures is discouraged, because
compaction will restrict or preclude the desired plant establishment. If compaction is necessary to
stabilize steep slopes or fill material, alternatives to mitigate this barrier to plant establishment
should be evaluated by a revegetation specialist. Soil auguring or ripping may be recommended to
enable adequate root growth in compacted soil.
Figures 15-19 illustrate several alternative bioengineering treatments, including: grading back slope
and planting, planted rip-rap at toe of slope, rip-rap with planting pocket, and terraced banks, These
figures represent conceptual treatments, and are not considered specifications. Other bioengineering
alternatives not illustrated include: sackcrete with mature trees, gabion structures with topsoil,
gabion blanket with planting cells or tubes, stepped-front gabion retaining wall with planting holes,
post and v'lire revetment, rail and cable revetment, geoweb cellular confinement system retaining
.
61
71
wall, low toe wall with slope flattening, live staking, live v,rillow posts, contour wattling, contour
brush layering, wire reinforced brush mats, brush deflectors, live wooden crib wall, \\rillow wall, .
anchored tree revetment, and rootwad boulder log revetment.
A document prepared by the Habitat Restoration Group entitled "Biotechnical Streambank
Stabilization", illustrates many of the bioengineering techniques employed in a v,ride range of
restoration projects. Only species native to the region should be utilized in the bioengineering
treatments. Plant palettes for trees, shrubs, and forbs and grasses are provided below.
.
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(\"
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Grading Back-Slope and Planting
.
.
13
CD Existing oversteepened slope
G) New graded slope
@ Rip rap
@ New veoelation
Figure 15
I
.
Toe of Slope Stabilized with Rip Rap
and Planted
Figure 16
1~
.
CD
@
Install planting collars
Install pole cuttings and baclctill
with approved topsoil (as approved by
Project Ecologist)
@
. -
Existing sackcrete-protected bank
.
.
Rip Rap with Planting Pocket
.
.
!j5
Cd) Shrubs and trees in planting pocket
CD Rip rap may be grouted and shall be
carefully placed. not dumped
@ Planting pockets to be 34-X 34- wide
Figure 17
r,
\....(' L,
,-r::: " ..;4 '1
? .7;)1
c " '\ J~'S
r c; VI
.... c... ....::> ..}.
l..t.. vi 1:,'
C. 01 -j.'
l..... v... " I
.. J >-) ,"
.: .' (". ~
. ..
7~
Terraced Banks for Slope Stabilization
High Terrace
Mid Terrace
Low Terra ce
Figure 18
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Terraced Banks for Slope Stabilization
CD
@
~
CD
Terrace may be stabilized
by rocks, logs. or low vertical walls
High Terrace
Mid Terrace
Low Terrace
.
Figure 19
'11
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?t
6.5 Protection of Specimen Trees
\\!hile the City of Dublin does not have a heritage tree ordinance, residents nevertheless have a
keen interest in protecting and maintaining native trees, especially oaks. Protection efforts should
be focused on the several native upland and riparian species, as well as some mature non-native
eucalyptus trees providing nesting habitat, that are found in and near Tassajara Creek and its
tributaries. Immature eucalyptus trees-should not be protected and may be removed as part of an
exotics eradication program. Mature eucalyptus determine by a qualified biologist to not be
providing important wildlife habitat may be removed.
Modification of the stream corridor to provide for flood conveyance and maintenance access will
in many cases require grading around these trees. Prior to preparing grading plans, all trees equal
or greater than 6 inches in DBH (diameter at breast height, or 4.5 feet above the ground) should
be accurately mapped.
'When these native trees or the mature eucalyptus occur within the area to be graded, a qualified
arborist should be consulted to determine whether the trees can be saved, and what procedures
should be employed. Emphasis should be placed on protecting, where possible, native and
mature eucalyptus trees that are equal to or greater that 6 inches DBH. For trees to be protected
during construction, a detailed set of tree protection guidelines should be developed, describing:
construction fencing, cutting roots in the least damaging manner, preventing the storage of
materials and equipment around protected trees, avoiding changes in drainage patterns around
trees, cultural treatments, construction monitoring, and other protection measures.
Construction monitoring by a qualified arborist should be required during grading near preserved
trees, to ensure the implementation of protection measures and to account for additional trees lost
during construction, for which mitigation should be provided.
To mitigate for the loss of native trees 6 inches in DBH or greater and mature eucalyptus trees
that cannot be saved during construction of the flood plain terrace and modifications to the
stream banks, three trees for each one removed should be planted and established. This translates
to a 3:1 mitigation ratio.
Container sizes for mitigation trees should be greater than or equal to citrus pots in size, but may
be as large as boxed specimens. Citrus pots are the optimum container because they support a deep
root system and moderate top size at planting time; pot size is 8 by 14 inches and volume is four
gallons. If all trees are grown in citrus pots, restoration success will be greatly enhanced.
Pole cuttings are acceptable for mitigation ofv..rillow or cottonwood species. In order to count
towards mitigation of removed trees, trees should be planted in the stream corridor ecosystem
where they are beneficial to wildlife: Street or landscape trees should not count towards
mitigation credits. Mitigation should be with the same tree sDecies as the trees that were
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68
removed, unless the trees removed were eucalyptus or other non-natives. Mitigation of non-
native tree removals should be with native species. Planting and establishment guidelines are .
provided in sections below.
Monitoring for a duration of five years should be required to ensure establishment of the
mitigation trees, with a general site review to occur a minimum of six times during the first year,
and twice per year annually thereafter.-A qualified monitor should conduct a quantitative
evaluation of the mitigation plantings twice in year one, and annually in years two through five.
This quantitative evaluation should measure and evaluate survival and native plant health and
vigor. Performance standards should focus on survival and growth. Growth, measured
quantitatively in the mitigation trees, should demonstrate a trend towards healthy establishment.
Tree survival within five years should be at least 85% in the fifth year. If over 100 mitigation trees
are planted, sample plots that will result in statistically representative sampling may be used to
reduce monitoring efforts. Monitoring should also trigger remedial actions, such as replacement of
mortality, control of exotics, repair erosion, addition or removal of tree cages, cultural treatments,
and other measures at the discretion of the monitor. Table 6 shows a schedule for the mitigation
monitoring.
6.6 Protection of Sensitive Resources
Sensitive resources include seeps, springs, ponds and the golden eagle nest in a tree along a
major tributary to Tassajara Creek in the northeastern portion of the Specific Plan Area. It is
possible that other sensitive resources will be identified during site analysis and planning of
Tassajara Creek and its tributaries. Protection of known and discovered sensitive resources
should be described prior to any construction of the flood plain terrace or modifications to the
stream banks. The protection of these resources during construction is a high priority. The tree in
which the golden eagle nest is located should be protected during and after construction as
should any other raptor nests encountered during any construction along the creek or tributaries.
Work around these nests should be scheduled to avoid active nesting. A qualified arbonst and
wildlife biologist should be consulted to determine the best methods to avoid impacts to the trees
with active nests.
.
Springs, seeps or ponds that occur within the Tassajara Creek corridor or tributaries should be
protected during grading. The functions and values of the seeps should be maintained, and
alterations to subsurface conditions that feed these aquatic features should be avoided. Seeps,
springs and ponds can create microclimate conditions that are favorable for wildlife or plant
species that have limited distribution elsewhere and are therefore of vital importance to native
flora and fauna.
Temporary or permanent fencing in habitat areas should be reviewed by a qualified biologist for
potential impacts to wildlife movement.
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69
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Construction fencing of ponds, seeps or springs should not interfere with migration of amphibian
species. Silt fences can be placed so as to allow migration at critical time periods during the
species life cycle.
Any permanent exclusionary fencing in the stream corridor or its tributaries should not present
barriers to wildlife. Five-strand barbed wire fences are compatible with ~ld1ife passage and should
be used.
Construction in the stream corridor should avoid the wet season, generally recognized by the
resource agencies to be October 1 through April 15. Both construction and restoration plans and
specifications should include detailed erosion sedimentation control elements.
6.7 Identify Opportunities to Integrate Mitigation into the Creek Restoration Program
Restoration is a general term that is often used interchangeably with ecological restoration, habitat
enhancement, habitat creation, revegetation, reclamation and management. For the purposes of this
document, the term restoration is used in the "general sense to include two strategies: habitat
enhancement and habitat creation. These restoration strategies are defmed as they are generally
used by restoration professionals in California and by the Society for Ecological Restoration.
Ecological Restoration is the process of intentionally altering a site to establish a defmed,
indigenous, historic ecosystem. The goal of this process is to emulate the structure, function,
diversity and dynamics of the specified ecosystem. Restoration is differentiated from other efforts
to establish plants in that the stated goal is to establish plants, animals, plant communities, natural
processes, functions and values that are self-sustaining over the long term. Restoration in the
Tassajara Creek corridor could involye habitat enhancement or habitat creation (mitigation).
Habitat Enhancement is the increase in one or more values of all or a portion of an existing habitat
through site alteration and for the improvement of a specific habitat function. Enhancement of a
degraded site D:lay include interplanting existing vegetation with indigenous species and removing
competitive weed species. If a riparian or wetland site is degraded, its enhancement is not deemed
creation or mitigation, because no new habitat results from the enhancement efforts. This is
consistent with the "no net wetland loss" policies of the state and federal regulatory agencies.
Habitat Creation or mitigation is the conver~ion of a site to a habitat type that has not existed there
in recent times (100-200 years). Created wetland habitats must occur on existing upland sites, and
almost always involve lowering the site to the water table appropriate to the target wetland type.
Habitat creation in the Tassajara Creek corridor should not be confused with habitat enhancement.
Habitat creation may be applied as mitigation credit for impacts elsewhere in the study area.
Mitigation or creation that is near the site of impacts and integrated with a larger restoration
effort of the stream corridor is consistent with conscientious bioregional planning and should be
encouraged.
70
Mitigation of ~abitat impacts originating within the Specific Plan study area should be encouraged
to occur within the Tassajara Creek corridor or its tributaries where feasible. TIlls can be
accomplished through habitat creation outside or within the actual channel.
.
Landscaping with natives adjacent to the trails located on or above the flood plain terrace is not
considered restoration, since most of the project restoration goals cannot be achieved at these
locations. For example, the groundwater table at these locations will most likely be too low,
restricting the new landscape's potential to emulate habitat structure, density, diversity, functions
and values found in native riparian systems. Additionally, many species of wildlife will not use
these landscaped strips because of the frequent exposure to trail users, and permanent irrigation
may be necessary to sustain these plantings so removed from the groundwater table. However,
these plantings should be compatible with the habitat enhancement located in the channel. Trail
landscaping will significantly improve the aesthetics of the site and will serve as a buffer to the
actual riparian corridor used by wildlife. Landscaping should use species native to the region and if
non-natives are used, these should be non-invasive species that cannot naturalize in the adjacent
natural areas.
Habitat impacts anticipated within the project study area that could be mitigated within the stream
corridor include: riparian, freshwater marsh, waters of the U.S., and habitat specifically for sensitive
species, such as the Califcrnia red-legged frog (Rana aurora dray ton i) and western pond turtle
(Clemmys marmorata). These species are Federal Candidates (List 1) for listing as threatened or
endangered, and California species of special concern. If construction is carefully planned, limited
impacts will occur with construction of the flood plain terrace, bridge crossings, creek low flow .
access, creek bank stabilization, check dams, and placement of engineering or bioengineering
structures. In most cases the required mitigation can be integrated into the project design, by
minimizing impacts, restoring natural contours, and revegetation with appropriate natives.
All mitigation proposals will require the review and approval of the regulatory agencies.
Ifhabitats for sensitive species are to be created in the Tassajara Creek corridor, grade
modifications which result in secondary impacts may be required. Mitigation plans should account
for these secondary impacts through avoidance, minimization and compensation.
Habitat creation or enhancement plans for sensitive amphibians should account for sedimentation
loads and flood flows in the Tassajara Creek system that could interfere with habitat creation
efforts. Analyses may show that sedimentation loads and flood flows work at odds with these
habitats, and that the tributary drainages to Tassajara Creek are in fact more suitable to amphibian
habitat creation. Obviously these habitats occurred historically in creeks with high flows, but
mitigation programs that require monitoring and performance standards for specific sites do not
have the flexibility to credit the applicant with washed out ponds that will be recreated elsewhere in
the creek system.
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71
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() (If--
Other issues the mitigation plan should account for include: pre-construction surveys for sensitive
amphibians and capture and release if deemed necessary by California Department ofFish and
Game and U.S. Fish and Wildlife Service; phasing habitat creation with other creek improvements;
fencing from cattle and other site protection; demonstrated appropriate hydrologic regime that can
provide for aquatic habitat of the frog and turtle (e.g. water retained in ponds from February until
September for red-legged frog); refugia sites to minimize poaching and predation; dispersal
corridors and breeding sites appropriate-to the sensitive species; measures to prevent introduction
of bullfrogs (Rana catesbeiana) or any fish species, including mosquito fish (Gambusia ajJinis)
as these species are predators on the eggs and larvae of the frog; mosquito abatement measures as
alternatives to mosquito fish; design of stand pipe to drain ponds should non-native predators be
detected; measures to discourage the dispersal of the frog and turtle into developed areas, such as
fencing or ensuring the accessibility of suitable dispersal sites; water quality of run-off and
aquatic sites; native plantings to enhance breeding habitat and provide cover; and construction
precautions, including fencing during construction that does not interfere with migration of
amphibian species.
6.8 Project Scheduling, Construction Restrictions and Coordination Requirements
Projects are phased when the project is too large or costly to execute at one time, or when land
ownership patterns and project administration imposes the need for phasing. In the case of
Tassajara Creek and its tributaries, phasing of restoration activities will likely coincide with
construction of the flood plain terrace, and the combined trails and access roads, and/or the
development activities of adjacent landowners. Phasing would allow the City of Dublin and
landowners to establish coordinated procedures for planning, plan review, permitting,
construction, maintenance and monitoring the creek and tributary projects. In the event of phased
development along the creek and its tributaries, all projects should adhere to these guidelines to
ensure comprehensive treatment of the stream corridors and protection of riparian resources.
Project construction should not begin until all required permits have been secured. In the event
that construction is phased, permits should be secured for the entire project before construction
begins in any area.
Construction in the stream corridor should be scheduled to avoid the wet season, generally
recognized by the resource agencies to be October 1 through April 15. Construction work should be
scheduled to avoid active nesting periods near the golden eagle nest, or any other raptor nests
encountered in the project area. A qualified .wildlife biologist should be consulted to determine
the best methods to avoid impacts to the trees with active nests.
Site access and staging areas should be identified and marked for construction and landscape
contractors, both on plans and in the field. Specifications should require use of designated
staging and access areas to ensure protection of sensitive areas.
-'")
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Protection of sensitive areas and activities restricted during construction and installation should
be clearly identified on plans and specifications. Flagging or construction fencing may be .
necessary and should be required if there will be equipment larger than pickup trucks anywhere
near the creek or tributaries. Contract sign-off, contract penalties and posting of bonds may be
tied to the protection during construction of existing sensitive resources, such as specimen trees,
nesting trees or active burrows, seeps, ponds or springs.
Final plans and specifications should address contractor and public safety, licensing and
qualifications of contractors, dust control, and site cleanup. Construction may disrupt wildlife
activities. Removal of vegetation and modification of the channel and creek banks will have the
greatest impact. Additional impacts will result from noise, dust and soil compaction. Site
modifications should be restricted during active nesting periods of sensitive species. Major site
modifications should be scheduled during late summer, when birds have completed nesting.
The final plans and specifications should provide specific schedule constraints. Biologically
important seasonal windows will govern most restoration activities, such as seed collections,
exotic plant eradication at specified times, construction outside of nesting seasons, and planting
and seeding prior to rains.
The final plans and specifications should be prepared by both revegetation specialists and
biologists experienced """lth biological resource planning and restoration planning and
installation. Installation should be overseen by a qualified revegetation specialist.
Project scheduling is a complicated task that requires the expertise of professionals with
implementation experience and familiar with the project's biological constraints. Conscientiously
planned and tightly managed scheduling will permit considerable efficiencies, cost savings and
necessary protection of biological resources. The project schedule should be integrated into
construction documents and contracts. Appendix 1 provides a structured approach to schedule a
restoration project, such as the restoration for Tassajara Creek and its tributaries.
.
6.9 Lighting in Habitat Areas
Trail planning should strive to locate trails away from the habitat areas in the Tassajara Creek
channel. Lighting in habitat areas should be avoided wherever possible because lighting has a
detrimental effect on certain wildlife species. However, should any trail segments with lighting
be situated adjacent to habitat (within 50 feet), low elevation light poles, low intensity street
lights and shielding the internal silvering of the globe or use of external opaque reflectors to
direct light at the ground should be employed to prevent adverse impacts to wildlife. These
details are graphically depicted in Figure 20.
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'tLl
-
-
-
Low intensity Street Ughts
Lighting in Habitat Areas
Foot path lighting
---- Figure 20
Low elevation light poles
CD IrXemaJ silvering of globe Iuminaire
@ Opaque reflectors 10 direc1light at grourx:l
.
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c. .d
6.10 Treatment of Transitions to OfT-site Open Space
Landscaping of trails and adjacent development is needed to create functional and aesthetic
transitions to open space, and is described in the next section.
Tassajara Creek functions as a major regional wildlife corridor, providing unintermpted
connections to Hidden Valley, Mt. Diablo, Morgan Territory, Camp Parks, Black Diamond Mines
and Contra Lorna Regional Parks, among others, Biological corridor connections from Tassajara
Creek to open space within and outside the Specific Plan Area should be provided through
Tassajara Creek and its tributaries. Biological corridors are open space areas that provide natural
cover and habitat for wildlife movement and reproductive exchange between plants. To function
properly, biological corridors require sufficient width to alIow unimpeded movement. Corridors
require connections to larger expanses of protected open space. 'Where the wildlife connections
along Tassajara Creek or its tributaries would be impeded by development, such as road
crossings, wildlife underpasses should be provided to mitigate impacts. California Department of
Fish and Game should be consulted on a case-by-case basis to review underpass dimensions,
placement and treatments to ensure compatibility with wildlife. Super span culverts are available
that allow for a natural bottom favorable to wildlife. It may become necessary to fence and/or
vegetate near the culvert to funnel wildlife into safe passage and away from roads,
The removal of the drop structure under Highway 580, under consideration by the County and
Zone 7 would be highly beneficial to wildlife movement.
6.11 Landscaping of Trails and Adjacent Development
Landscape plans should employ unifying design principles for the entire Tassajara Creek stream
corridor and its tributaries. The City of Dublin will evaluate submitted trail landscaping treatments for
their compatibility with other properties along the stream corridor. 'Where single loaded streets abut the
stream corridor, landscaping should not interfere with the ability of local police to visually inspect the
trail while driving by.
'Where the stream conidor abuts parks, the park landscaping and grading should integrate the stream
corridor by linking the trail with park circulation and using compatible landscaping. Active park uses
however, should not be allowed within 100 feet of the riparian conidor in the creek channel.
Storage and loading facilities and dumpsters associated with adjacent cOD?IDercial development, should
be screened from trail views with appropriate landscaping.
Because the groundwater table at the trail locations is so removed, permanent inigation may be
required to sustain plantings, which is consistent with the landscaping and fire management goals.
Alternatively, very drought tolerant species can be established with temporary inigation systems. Table
5 lists recommended prohibited landscaping species that are mown to invade and overtake natural
areas.
75
The native riparian and oak woodland species provided in the restoration plant palettes are among
the many species native to the region that ifused in the landscaping would be compatible with the .
restoration efforts, and would provide bird habitat. The riparian species, if utilized in the trail and
adjacent trails landscaping, would likely require permanent irrigation. If oaks are used, plantings
under oaks should follow the guidelines specified below for oak plantings. Suitable tree, shrub,
grass and forb species are presented for restoration, and landscaping plants can be selected from
these for maintenance and aesthetic considerations.
6.12 Interpretation
Through implementation of the Specific Plan, the City of Dublin faces the challenge of encouraging
public access and enjoyment of the stream corridor, while protecting sensitive nesting periods of both
resident song birds and other wildlife species. Appropriate interfacing of habitat with urban elements is
accomplished with buffers, trail design and interpretation. The rich ecological and aesthetic resources
of the stream corridor present numerous opportunities for interpretation. A simple and inexpensive
vehicle for interpretation and community involvement is the installation of bird nest boxes, described
below.
Interpretative signing can focus on natural features and natural processes of the riparian ecosystem.
Intriguing educational captions can focus on raptors or other inviting wildlife subjects. The numbers of
species using a culvert underpass for safe passage is a possible topic. Natural processes that convey the
dynamic and forceful nature of natural river systems can be illustrated along the trail. Riparian
vegetation is dependent upon the natural disturbance of flood flows to regenerate, which can be
illustrated by the range in age and habitat structure, Selected aquatic environments present interactive .
opportunities for children to observe natural behaviors and appreciate habitat protection.
Sensitive aquatic habitats, such as those known to support California red-legged frog, should not be the
focus of interpretation or a trail designation, because it will draw undesired attention to the habitat and
is known to result in poaching of the species.
Assistance in development of an interpretation program can possibly be obtained through the
Alexander Lindsay Junior Museum in Walnut Creek, or East Bay Regional Park District.
6.13 Installation of Bird Nest Boxes
Natural tree cavities are relatively rare in most habitats. The availability of nest sites for cavity-
nesting birds probably limits the numbers ofthese species along the creek corridor. The
installation of nest boxes or nest shelves would provide nest sites and cover for many species of
birds, as well as mice and other small mammals. Volunteer labor to install nest boxes or nest
shelves can possibly be obtained through the Alexander Lindsay Junior Museum in Walnut Creek,
local Scout troops, and school-age children in Dublin. The City of Dublin can encourage these
groups by disseminating this information.
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Nest boxes are available in most garden centers, many lumberyards, and sometimes in craft stores
and the 'Nature Company' catalogs. Prices vary depending upon size and quality but most nest
boxes cost between $8 and $20. Sources of nest boxes include: Wild Birds Unlimited, 692 Contra
Costa Blvd., Pleasant Hill, CA 94523, (510) 798-0303; Backyard Birds & Co., 717 S.
Broadview, Springfield, MO 65809-0712; For the Birds!, P.O. Box 491, Hovland, MN 55606;
and WIldlife Studio, 7 Patton Road, Bedford NH 03102.
Figures 21 and 22 illustrate several nest box designs and a sample building plan. Nest boxes are
easy to construct. Nest boxes should be made of pine, fir, or some other soft lumber. The walls
. should not be over one inch thick. Boxes with open or removable roofs are recommended, to
allow access to the interior. Boxes or shelves may be unfinished or painted. If the box or shelfis
painted, use neutral gray, brown, or green. Excessive heat can kill nestlings. Ventilation can be
provided by drilling two small holes in the floor, and two small holes in the top of one of the
walls.
It is not efficient to have too many nest boxes in a limited reach of creek, as birds are territorial
animals. Therefore nest boxes should be placed 30 to 100 feet apart, and neighboring boxes
should be designed to attract different species. Along the linear corridor of the creek, no more
than four to six boxes should be placed every 500 feet. It may not be necessary to be so restrictive
with the number of nest shelves installed.
Nest boxes should be cleaned after every nesting season. All old nest material, remaining
eggshells, and other debris should be removed.
77
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Figure 21
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~1
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I,., ~
(jff ~~
~. .. ~. . . ... - .
..........~ .
Figure 22
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~o
Bats are also an important component of the native ecosystem, and development has greatly
reduced their habitat. Bat nest boxes can also be purchased or constructed with kits available
from the Lawrence Hall of Science gift shop in Berkeley, (510) 642-1929. Information on bats
can be obtained from Bat Conservation International, (800) 538-BATS.
Some of the species that nest boxes or nest shelves would benefit include: chestnut-backed
chickadee, house finch, American robin, Bewick's wren, white-breasted nuthatch, ash-throated
flycatcher, barn swallow, and black phoebe. Bat species that occur locally include: California
myotis, little brown bat, Mexican free tail bat, big brown bat and the Brazilian bat.
6.14 Restoration Treatment of the Three Reaches
Restoration treatments in the Tassajara Creek corridor and its tributaries will vary as a function
of current conditions, project goals and proposed modifications. Guidelines for restoration
treatments, from exotics eradication to irrigation are presented below, and their application will
vary with the extent of restoration treatments incorporated for a particular reach. For example,
plants will be established at greater densities in bare soil areas and less intensively when
interplanting a well-vegetated reach.
As discussed in detail in ihe section on groundwater testing below, each native riparian species has
unique groundwater distance requirements and tolerances. The proper placement of plants within
specified planting zones should reflect their natural positions with respect to the groundwater
profile, and is based on their ability to reach the water table or to tolerate drier conditions. In the
Tassajara Creek system, riparian species can be self-sustaining in the absence of permanent
irrigation when placed in the creek channel itself. Riparian plantings on the flood plain terrace
however, are not feasible because of the distance to the groundwater table.
The flood plain terrace outside the creek channel should be managed for low growing, low
maintenance non-irrigated grasses. This zone, e>...'tending along either side of Tassajara Creek and
its tributaries, is too high above the water table to support volunteer willows, and is expected to
support native and annual grasses and wildflowers. The zone will vary in width, depending upon
the size of the stream corridor cross section and can be managed with mowing, which is
preferable to disking. Thorough control of the noxious weeds, such as yellow star thistle will be
necessary prior to seeding, as will aI?propriate debris removal and seed bed preparation.
Complete eradication of the exotics should not be expected, however a competitive edge can be
given to the natives if an aggressive exotics eradication program is pursued, If seeded in the fall
prior to onset of rains, no irrigation should be required. A seed mix for this zone is provided and
can be modific:d with Ca)jfornia Department ofFish and Game approval.
80
The lower reach of Tassajara Creek, between Highway 580 and Gleason Road requires
substantial restoration plantings in the creek channel, due to the proposed modification in
Subreach 1 and the lack or habitat structure and diversity in Subreach 2. Plantings with native
riparian species are required by California Department ofFish and Game and are consistent with
the Specific Plan. Because plantings will increase resistance to flood flows, hydrologic modeling
and sizing of the channel must acco\lIlt for the vegetation. Zone 7 (Mr. Jack Fong, personal
communication) has suggested the exclusion of willow from the plant palette for this reach, but
inclusion of the other riparian tree and shrub species. This compromise is acceptable for this
reach only, but the hydrologic models should anticipate naturalization of some willows. Native
plantings shouJd be at densities sufficient to provide wildlife habitat, for example trees on 25-35
foot centers (25-35 feet apart), and shrub masses a minimum 25 feet apart with the shrub plants
themselves on 3-10 feet centers. Actual spacing is dependent upon the species used and the
available groundwater. A palette for native grass and forb species is also provided.
The tributaries ofTassajara Creek present s~gnificant opportunities for mitigation. Many are
currently disturbed or will be sufficiently modified to require considerable mitigation plantings.
If a tributary \\'ill not be improved through the mitigation of project impacts, restoration of
tributaries that are important to wildlife movement is recommended. In particular, native
revegetation near wildlife undercrossings, complemented by fencing, is critical to the functioning
of the stream corridor. Locations where large debris is removed will require native revegetation.
Native plantings, consistent with the plant palettes provided for tree, shrub, forb and grass
species should be at densities sufficient to provide the wildlife habitat. Groundwater availability
of the subject tributary should be understood and should dictate fmal planting densities. "Where
seeps and springs occur, densities may be greater than where conditions are drier. Approximate
spacings are: trees on 25-35 foot centers, and shrub masses a minimum 25-35 feet apart with the
shrub plants themselves on 3-15 feet centers. Actual spacing is dependent upon the species used
and the available groundwater.
The middle reach ofTassajara Creek, from Gleason Road up to and including the East Bay
Regional Park District staging area, although primarily well vegetated and requiring no
restoration, has isolated patches requiring exotics eradication, debris removal and restoration
plantings. A qualified biologist should identify the areas that merit restoration, and the species
selected and planting densities should reflect the species and densities observed in the adjacent
intact (reference) areas. The planting zones for the various species can be readily interpolated
through the adjacent vegetative indicators. Approximate spacings are: trees on 15-25 foot
centers, and shrub masses a minimum of 15-25 feet apart with the shrub plants themselves on 3-
15 foot centers.
The upper reach of Tassajara Creek above the East Bay Regional Park District staging area to the
County line, presents three scenarios, all of which should be identified by a qualified biologist
and hydrologist. First, there are stretches along Tassaiara Creek in this reach that are well
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vegetated and require no restoration. These stretches will be further enhanced by the eventual
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exclusion of cattle and horses in the creek, pursuant to the EIR and Specific Plan. Second, there
are stretches requiring exotics eradication, debris removal and restoration plantings. Third, at the
very northern stretch of Tassajara Creek, many of the banks are near vertical or overhanging, and
there are numerous piles of rubble, some of which should be removed. Inherent in the planning
and restoration treatment of this area is adequate hydrological and biological wildlife, discussed
in earlier sections. Restoration in these steep banked areas could entail leaving the banks alone,
seeding bare soil areas on the banks witl1 natives where feasible, and providing mitigation for
public safety. Near vertical banks can be seeded in some cases, but planting should be prohibited
because the activity will exacerbate erosion and is prohibitively dangerous to contractors. Should
the land owners desire, or East Bay Regional Park District require, isolated repairs of vertical or
overhanging banks could be made and revegetated with natives, for the sole purpose of public
safety. Treatment of these banks is not indicated for biological and hydrological reasons, and
should be left to the discretion of the City of Dublin, the landowners and East Bay Regional Park
District. (Zone 7 has indicated that the conditions of this reach are inconsistent with their
maintenance criteria and they will not likely take management of the flood channel north of the
East Bay Regional Park District staging area.) If isolated repairs were made, significant efforts
should be made to preserve the uniqile aesthetic values in many of these banks. Riparian plants
are expected to regenerate naturally when cattle no longer water in the creek. Areas denuded by
debris removal should be planted and/or seeded. Species and planting densities should reflect the
species and densities in the adjacent intact (reference) areas. Seeding in this reach may require
adjustment of the palette should the soils tests reveal salinity or other severe conditions. The
alkali grassland above the creek to the east supports several native grasses adapted to the unique
soil conditions.
6.15 Exotics Plant Eradication
The restoration program requires both the initial eradication of invasive exotics prior to
revegetation and the continued control of these aggressive species as they attempt to recolonize the
site. Construction and site-modifications will create open areas that are prime sites for opportunistic
exotics. Given the urbanizing setting and constant exposure to exotic seed sources, complete
eradication is not realistic. For these same reasons, in order to recapture the site for natives, certain
exotics should be completely removed prior to the revegetation phase. In the follow-up
maintenance program, the spread of the exotic species is checked. Desirable native plants, including
riparian and upland tree species, salt grass, mugwort, California wild rose, poison oak and wetland
plants should be protected during eradication efforts.
Exotic species to eradicate include, but are not restricted to: annual grasses, yellow star thistle,
cocklebur, common fennel, thistles, nutsedge, mustard, curly dock, prickly ox-tongue, rabbits foot
grass, Bermuda grass, Scotch broom, tree tobacco, and poison hemlock.
To effectively control exotic plants throughout the Tassajara Creek corridor and its tributaries, a
\vide array of treatments should be available, including conservative application of herbicides,
manual and mechanical methods. Mechanical or manual eradication of exotic species should take
82
precedence over chemical eradication whenever it can be economically justified, in order to
minimize potential impacts to aquatic organisms. Frequently, a combination of mechanical removal .
and localized chemical treatment will eradicate the plant while minimizing the use of chemicals and
environmental contamination.
The restoration program should include a discrete exotics eradication plan that is conducted for a
sufficient time period (1-12 months is n6t uncommon) to ensure adequate site preparation.
In final plans and specifications, the revegetation specialist should develop a list of exotic plants to
eradicate, specify detailed eradication methods for each species, specify tolerances for these plants
after treatment, and identify the seasonal windows when target species are most susceptible and the
removal opera~ion is most cost effective. Timing of seed production of the exotics should be
considered when planning eradication efforts.
\Vherever possible, organic debris generated by the eradication of exotic species should be removed
manually, not mechanically (i.e., no heavy equipment). Appropriate disposal of organic debris
should be ensured.
For many exotic species, if there is any seed present at the time weeds are killed, the seed heads, or
in some cases, the entire plant, should be bagged and disposed of properly off-site. This holds for
tree tobacco and cocklebur, but not for yellow star thistle and annual grasses.
Although manual eradication is preferable, it is labor intensive and can require several months, or .
years, of repeat treatments. Combining manual eradication with restricted chemical treatments
provides effective results in a short time period. If this project does not have the schedule flexibility
to dedicate years to eradication of exotic species, the limited use of an herbicide is recommended.
The only herbicide that could be used within 75 feet of the creek is glyphosate, trade name Rodeo,
in a wetland formulation. Under no circUmstances should herbicides should be used within
approximately fifteen feet of creek water and aquatic sites, or where spray drift or runoff could
contaminate the water. Roundup, glyphosate with a surfactant that is toxic to aquatic organisms
could be used in controlled circumstances for upland applications.
The final plans and specifications should prescribe all chemical applications and address the
number of applications, treatment of re-growth, schedule and climatic constraints, disposal of spent
containers and safety precautions. Specifications should emphasize that the herbicide contact only
the target plant, 'with no chemical contacting .the surrounding vegetation. Broadcast spraying of
herbicides is not recommended. Painting the chemical directly onto a fresh wound of the target
plant produces the optimal effect of controlling exotics while minimizing chemical use. All
chemical applications should be conducted under the supervision of a Licensed Pesticide
Applicator and a knowledgeable revegetation specialist. 'When treating woody species with
chemical, only the cambium section of the outer trunk is painted and the effective time lapse
between cutting and treatment is limited to two minutes or less.
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. Annual ruderal weeds may be grubbed out manually, weed whipped or mowed.
6.16 Debris Removal
Non-organic debris or rubble has been dumped into the Tassajara Creek channel and its tributaries
at various locations throughout its course within the project area. The debris includes concrete
rubble, asphalt, trash, autos, tires and more. In the final planning phase, restoration planners should
evaluate situations in which the concrete may be used in hard structures.
Much but not all of the debris or rubble should be removed. All rubble should be mapped and
evaluated with the following ecological and aesthetic criteria to determine whether it should be
removed. Prior to removal and as a part of evaluating the feasibility of removal, the hydraulic
influences of its removal should be determined by a qualified engineer.
Rubble should be removed from banks and the low flow channel wherever it has the potential to
affect water quality or is hazardous, such as asphalt, tires, autos or barrels of unknown substances.
Rubble should be allowed to remain in the low flow channel where it is not hazardous or
detrimental to water quality. Rubble should be allowed to remain on the banks, where it can be
demonstrated that it is not hazardous or detrimental to water quality, cannot be seen from trails or
overlooks, is not readily removed by equipment available during the construction phase, and is not
. greater than 10.0 square feet in size.
All removal of rubble should be followed with a planting and or seeding restoration program.
Final plans and specifications should address removal and disposal of non-organic debris. If not
useable in the project, the debris should be removed from the site and disposed of properly in a
landfill. .
Final plans should address the removal and disposal of organic debris. In many cases, thatch from
dead exotic vegetation should be removed from the site to avoid further invasion of the site with the
undesirable seed or propagules.
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6.17 Soils Testing and Treatment
Soil testing is an integral step in the design and implementation of a successful restoration
program because soil toxicity or incompatibility problems, such as excessive salinity, alkalinity
or the overabundance of certain elements, such as boron, cannot be readily determined in the
absence of agricultural suitability tests. These problems have the potential to result in widespread
plant mortality or poor growth performance if left undetected. The primary goals of the soils
testing is: to identify an appropriate plant palette, identify difficult soils and possible soil
treatments, detect the v82:ation in the soils throughout the restoration sites, and to determine
cultural regimes during establishment maintenance. At least three composite soil samples should
84
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be collected from different planting zones (low, mid and high), at a minimum of half mile
intervals on both sides of the creek (totaling 6 samples) wherever restoration plantings are .
planned. A single composite sample is collected by sampling soil to a depth of 24 inches from
five sub-locations within that planting zone, for that distinct reach and side of the creek The soils
samples should be properly labeled and sent to a qualified soils laboratory for an agricultural
suitability test and analysis.
A copy of the soils report and recommendations should be provided to the City of Dublin when
submitting restoration or mitigation plans for review. Recommendations may correct for pH or
fertility problems, or improve permeability. However, certain soil conditions should dictate a
change in the plant palette rather than the soils, if the soils support a unique plant community,
such as alkali grassland. The restoration plans should reflect the soils analysis and
recommendations. A qualified laboratory experienced with native restoration and known to give
thorough and accurate ar~alysis is: Dr. Garn Wallace, Wallace Laboratories, 365 Coral Circle, EI
Segundo, CA 90245 (310) 615-0116.
Prior to any site disturbance, a qualified restorationist with experience in topsoil salvage and
storage should be consulted to determine the need and options for topsoil salvage and storage. In
the event that topsoils are removed during site disturbance, a qualified soils scientist should be
consulted on the replacement of topsoils to help ensure that restoration plantings succeed.
If soil is stockpiled, it should be protected from moisture to preserve microorganisms living in the .
soil that are beneficial to native plants. Stockpiling of soil for long periods of time, however, will
destroy desirable microorganisms, such as mycorrhizae (beneficial fungi living in the soil). Soils
should not be stockpiled for more than 16 months, preferable less than 12 months.
Wetland soils should not be mixed with upland soil stockpiles. A qualified restorationist should
monitor any wetland soil excavation to ensure that soils are not excavated too deeply, which would
dilute the value of the soil layer, or too shallowly, leaving behind useful material.
Topsoils for all soils to be stoch..'J)iled should be separately piled to enable the contractors to
distinguish between subsoils and the more valuable topsoiL Similarly, all piles of soil that are
stockpiled shoUld be labeled and/or mapped on plans to allow contractors to distinguish between
them for the purposes of replacement. All salvaged and stored soils should be placed on ground
tarps at approved staging areas and piles. Salvaged soils should be placed on a geocloth or some
other type of membrane to prevent contamination and moisture uptake from the ground during
storage. Soil piles should be covered with plastic sheeting and staked to hold the sheeting in place.
The covers should be reflective to reduce heat, but should be placed in a manner which allows
venting in order to evacuate heat produced by decomposition. Soil stockpiles should be linear rather
than one large heap to reduce decomposition and heat diffusion. This would allow for limited
drying of soils during storage. Piles should not exceed four feet in height. 'When replacing
stockpiled soils and recontouring, the contractor should account for settling.
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It is recommended that soils testing and groundwater testing, as described in the next section,
should be conducted concurrently.
6.18 Restoration Plant Palette
Table 1 shows the species recommended for use in creek restoration, grouped as trees, shrubs, and
grasses and forbs. The majority of these species listed in the plant palette are local to the region.
Some of the species are native to other regions of California and were included for their wildlife
values, aesthetic attributes, and contribution to wildlife species diversity. Additions may be made to
the plant palette if the species are native to the region. Species diversity is essential to restoration
and should more natives become commercially available in the future, these certainly may be
included in the palette. The table presents the recommended propagation method, particular wildlife
habitat value, and a slope stabilization rating for each species. Applicant's plant palettes may vary
from Table 1, but should be restricted to species native to the region.
For many of the same species in the plant palette, Table 2 gives the growth habit, general habitat
description. The last column is left blank to assist restoration planners in the field in noting whether
the species is growing in the reach for which the restoration is being planned. Species from the
plant palette may be used anywhere in the project area, however an emphasis on the species
performing well in the reach is recorr:mended.
Serious consideration was given to commercial availability in the development of the plant palette.
Although limited in numbers, seed suppliers and nurseries that can provide the native plant and
seed materials do exist. In addition, many of these operations will provide custom seed and plant
collections as well as custom propagation of locally collected stock.
6.19 Groundwater Testing and Planting Zones
Planting zones within riparian habitats are determined by th-e distance to the groundwater. In a
system such as Tassajara Creek, groundwater is close to the surface at the midpoint of the low flow
channel and drops on either side of the low flow channel, with the groundwater profile resembling a
parabola The depth to groundwater increases with the horizontal distance from the centerline of the
creek, and the vertical distance above the low flow channel. Creek downcutting increases the
distance to the water table, and existing trees may have established in times when the groundwater
table was closer to the surface. Native plants have adapted to natural conditions and can survive in
the absence of permanent irrigation if established on appropriate sites. Each native riparian species
has unique groundwater distance requirements and tolerances. The placement of plants within
specified planting zones should reflect their natural positions with respect to the groundwater
profile, and is based on their ability to reach the water table or to tolerate drier conditions.
86
The groundwater profile and associated planting zones should be established for any reach subject
to a planting plan (Figure 23). Distance to groundwater can be determined with piezometers or can .
be interpolated through vegetative indicators"by a qualified plant ecologist, who can account for
downcutting effects on the water table. Local groundwater studies indicate that groundwater
supplies for plantings in the lower reach may be severely limited, due to infiltration to the deep
aquifer. Groundwater testing is imperative.
Riparian tree species should be planted in zones defined by proximity to the water table, shade
tolerance, and cultural requirements.
The lowest planting band in the creek channel, within three feet of the water table, will support the
three 'willow species in the plant palette. Note that distances to the water table are approximate and
may vary slightly with the particular site.
The nex1: planting band within the creek channel, located three to six feet above the water table, will
support cottonwood, box elder, ash and alder.
The next planting band within the creek channel, located six to ten feet above the water table, will
support sycamore, valley oak, buckeyes and walnut.
The upland species typically associated with.a riparian zone are established within a deeply incised
channel and on the top of the bank. The species to be planted at distances greater than ten feet .
above the water table included: live and blue oaks and big leaf maple.
Plant layout should reflect the limited shade tolerance of most riparian species. Bay trees, however,
are uniquely shade tolerant and can be interplanted from three to ten feet above the water table, in
areas with an existing partial canopy.
Cottonwood and willows should be emphasized in plantingsbecause they provide rapid slope
stabilization and tree cover for both the stream channel and slopes. In addition, cottonwood and
willows are the dominant species in the better developed local riparian stands. Because of their
rapid growth rates, these species are especially appropriate for planting into bioengineering
treatments.
The flood plain terrace located outside and above the creek channel should be high enough above
the groundwater table to discourage natural recruitment of the riparian tree species, such as willow
and cottonwood. This large upland area, which serves as a buffer to the riparian corridor, will be
maintained with a low ground cover, primarily native and annual grasses, and will provide the flood
control for 100 year flows.
The distance to the groundwater table for the landscaping associated with the trails will largely
exclude riparian species. In these landscape strips, very drought tolerant species native to the
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region should be emphasized, as discussed above in a section on landscaping of trails and
adjacent development.
6.20 Planting Under Oaks
California's native oak species are adapted to the region's dry summers. Consequently, any
landscaping or wildlife habitat plantings within the driplines of established oak trees in the
Tassajara Creek corridor and its tributaries should have water needs that are compatible with the
oaks to minimize the chance that overwatering would promote oak root disease. Planting under
existing oaks should be restricted to the species in Table 3. Both wildlife habitat enhancement
plantings near the channel and native landscaping under oaks near the trail should incorporate
appropriate species from Table 3.
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Planting Zones
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Zone 4
Zone 3
Zone. 2
Zone 1
Zone 2
Zone 3
Zone 4
Common Name (Sdent;(ic Name)
Zone 1
Zone 2
Zone 3
Zone 4
.
Willow (Salix spp.)
White alder (Alnus rhombifolia)
x
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Box elder (Acer negundo ssp. califorical
Oregon ash (Fraxinus latifolia)
Fremont cottonwood (Populus fremonthl
California bay (Umbellularia californica)
Buckeye (Aesculus californicusl
Black walnut (Juglans hindsm
Western sycamore (Platanus racemosa)
Valley oak (Quercus lobata)
Big leaf maple (Acer macrophyllum)
Madrone (Arbutus menziesill
Coast live oak (Quercus agrifolial
Blue oak (Quercus douglasm
__ Figure 23
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Plantings should not be 'within ten feet of oak trunks. Care should be taken to ensure that irrigation
drains away from oaks. If plantings need water through the first summer, a mulch-covered above-
ground drip irrigation system should be used.
If open areas under oaks are desired to preserve view corridors, Elymus triticoides and E. glaucus
plantings are recommended.
6.21 Container Sizes and Plant Spacing
Figure 24 illustrates a typical planting detail for installation of container plants and blackberry
cuttings.
Appropriate container sizes for trees are: citrus pots or five gallons for planting pockets, minimum
of one gallon size for interplanted areas, and minimum of one gallon size for planting open areas.
Citrus pots are the optimum container because they support a deep root system and moderate top
size at planting time; pot size is 8 by 14 inches and volume is four gallons. If all trees are grO\\r.I1 in
citrus pots, restoration success will be greatly enhanced. Trees planted to mitigate removed trees
should be citrus pots or greater in size.
If employed in a bioengineering treatment, interplanting of trees in planting pockets should allow
approximately ten to tVventy foot spacing between trees. Citrus pots are preferred, but five or fifteen
gallon containers are acceptable, and pole cuttings may be used for willow and cottonwood
plantings.
Trees planted in bare areas, graded areas, or where debris was removed or exotic plants were
eradicated, should be spaced according to the species and the groundwater availability in the reach.
Spacing is discussed in the section on restoration treatments above. Spacing and layout should
always emulate a natural configuration. The container size can be citrus pots, five gallons or one
gallon plants, but citrus pots are favored.
Shrubs should be liner or one gallon size and planted in shrub masses as described in the above
section.. The planting pattern should emulate natural spacing and distribution patterns. Shrub
masses or groupings can be planted in openings where they will not be shaded out by the tree
canopy.
Blackberries and native roses may be planted in thickets on eighteen inch spacings with a minimum
of ten plants per thicket. These shrubs may also be interplanted or planted over large areas, for their
slope stabilization and buffer strip values.
Since purple needle grass is a poor seeder, liners may be used to establish stands of this attractive
bunch grass.
90
Blackberry Detail
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Planting Detail
CD Planting pit to be twice as wide
and twice as deep as plant container.
@ Break up large clods.
o Timed-release fertilizer tablets
(2 for each planting pit)
@ Fill planting pit with water and
allow to percolate (drain) into subsoil
@ Place some backfill material into
the bottom of the pit, moisten and tamp,
and mound slightly
@ Set plant root ball atop the moistened
backfill so that the plant collar is 1"
higher than the fmished grade.
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@
With water lIowing slowly into the hole,
replace backfill material up to 213 the
height of the root ball, moistening, tamping
and settling all around the plant
Fill remaining portion surrounding the top
of the root ball with more backfill. Make
sure that the collar is still higher than grade
Create an irrigation basin outside the dimension
of the hole using remaining backfill and native soil
@
@
@
Apply a generous portion (approx. 3" deep) coarse,
organic. weed and disease-free mulch: topdress around
exposed collar and inside the entire basin area. Taper
away from branches to avoid stem rot.
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Figure 24
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6.22 Plant and Seed Procurement
The plant species provided in the plant palette have been carefully selected for their adaptation to
the habitats to be enhanced and created, and because they are native to the area. These species,
properly planted and cared for offer the best chance of survival and success in the absence of
permanent irrigation. Therefore, only species from the approved list of native species should be
planted within the Tassajara Creek corridor and its tributaries, including the wildlife habitat and
trail landscaping areas. Species substitutions by contractors should be with species from the
approved plant palette and specificati.ons should state that substitutions should be avoided if
possible. Should substitutions be necessary, approval by a representative of the City of Dublin and
the revegetation specialist will be required.
Grass and forb .species for the creek banks in the riparian areas are limited to native species. 'While
species on in the flood plain terrace mix emphasize native species, non-native grasses are expected
to invade the terraces. If erosion control is a consideration, a non-native nurse crop Plantago
insularis (at approximately 20 pounds per acre) can provide rapid germination, stabilizing soil until
the desired plants are established. Plantago insularis is recommended because it does not compete
Vvith natives and is non-persistent, i. e., it dies. within a few seasons.
To protect the gene pools of the local native plant populations and help ensure the success of the
'wildlife habitat and landscaping plantings, the use of local sources of container plants and seed are
encouraged. Local is either from the Tassajara Creek watershed or from southern Contra Costa
County or northern Alameda County. Suppliers and nurseries providing stock should certify the
origin of their seed and plants. Additional information may be requested, such as the number and
spacing of donor plants. The revegetation specialist should review proposals to use stock that does
not originate from this area
Plants and seed should be ordered in advance (or contract-grown) to ensure that the species, sizes, ,
and plants of local origin are available when needed. Advanced ordering is absolutely critical and
its importance cannot be over-emphasized.
6.23 Mycorrhizal Fungi
Rapid growth and establishment of plants on a restoration site is vastly improved with the presence
of mycorrhizal fungal associates of the plants. Mycorrhizae are specialized fungi found on plant
roots. A mutualistic relationship exists between plant roots and mycorrhizae. Plants benefit from
increased ability to take up nutrients and withstand drought when mycorrhizae are present. This
relationship is essential to the growth rate, well-being and longevity of natural plant communities.
Site disturbances, such as grazing, can cause mycorrhizal fungi to die out through elimination or
suppression of their host plants. Although mycorrhizal fungi can re-invade if suitable host plants
and other conditions are in place, re-invasion is often very slow. Utilization of mycorrhizal fungi
markedly increases the success of restoration on disturbed or degraded lands. The presence of
mycorrhizal fungi is knO\V to favor native plant establishment over weeds. Additionally, it has been
92
demonstrated that the presence of mycorrhizal fungi is critical for regeneration of natural
ecosystems in arid lands.
.
The presence of the appropriate mycorrhizal associates makes the difference between installing an
artificial landscape and restoring a functional ecosystem. Soil biology is restored over the long term
through slow establishment of native plants. Alternatively, container plants procured for restoration
can be inoculated with the appropriate niycorrhizae, which then spread to other plants on the site as
they become established. Tree of Life Nursery in San Juan Capistrano, California provides
inoculation of their mature plants.
6.24 Storage and Handling of Seed and Plants
All container plants should be hardened-off at the nursery prior to delivery or pick-up. The extent of
hardening-off should be appropriate to the season of the year when planting occurs.
Storage, handling, and inspections of the seed and plants should be addressed in the final plans and
specifications. Plants should be inspected for correct species and quantities, health, vigor,
acceptable root-to-shoot ratio, circling roots, growth and form, and should be visibly free from pests
and diseases.
Plants and seed should be kept in a cool dry place, protected from wind, heat and other
conditions which would damage or impair viability, both during delivery, and when temporarily
stored on site prior to planting. Onsite storage time should be minimized.
.
6.25 Commercial Sources of Plant and Seed Materials
Several nurseries experienced in propagation of California natives are listed below. As discussed
below, planning is required to allow custom growing of genetically local stock for the Tassajara
Creek wa~ershed or the loc8J. counties. Current availability of plants and seed from the plant palette
.. for the wildlife habitat and trail landscaping areas was not verified for this report.
Nurseries include:
Cornflower Farms
P.O. Box 896
Elk Grove, CA 95624
(916) 689-1015
Los Robles Native Plants
P.O. Box 449
Gerber, CA 96035
(916) 385-1205
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Native Here Nursery
101 Golf Course Drive
Berkeley, CA 94708
(510) 549-0211
Pacific Open Space
P.O. Box 744
Petaluma, CA 94953
(707) 769-1213
Sk)'lark 'Wholesale Nursery
6735 Sonoma Highway
Santa Rosa, CA 95405
(707) 539-1565
\Vapurnne Native Plant Nursery
3807 Mt. Pleasant Road
Lincoln, CA 95648
(916) 383-5154
Yerba Buena Nursery
19500 Sk)'line Blvd.
Woodside, CA 94062
(415) 851-1668
Additional sources of plant materials include the California Department of Forestry Reforestation
Center in Davis (916-753-2411), and the California Conservation Corps Native Plant nursery in
Napa (707-252-7783).
Seed companies specializing in native seed are listed below:
Albright Seed
487 Dawson Drive, # 5-S
Camarillo, CA 93012
(805)484-0551
Conservaseed
P.O. Box 455
Rio Vista, CA 94571
(916) 775-1646
94
Hedgerow Farms
21740 County Road 88
Winters, CA 95694
(916) 662-4570
.
Lamer Seeds
P.O. Box 407
Bolinas, CA 94924
(415) 868-9407
Pacific Coast Seed
6144 Industrial Way, Suite A
Livermore, CA 94550
(510) 373-4417
S&S Seeds
P.O. Box 1275
Carpinteria, CA 93013
(805) 684-0436
6.26 Genetics Conservation Guidelines
Restoration goals establish the need to use seed and plant stock from local gene pools. The goals .
reflect the e:x."tent of the City's desire to assume this commitment. Custom propagation is not
necessarily more expensive, but it requires advanced planning.
This plan endorses a moderate approach, emphasizing genetic conservation of species currently
growing within the watershed, followed by a best effort to collect from the Alameda/Contra Costa
area ifwatershed propagules are limited. This approach would include seed and cutting collections
from donor plants within the Tassajara Creek watershed, and purchase of seed and container plants
from elsewhere in northern Alameda County. or southern Contra Costa County. Procuring local
stock from trees is a priority, however, because they are long-lived. Several species in the plant
palette, such as the native bunch grasses, cannot be collected locally, but their use in restoration
would increase diversity and greatly enhance aesthetic and wildlife values. It should be
remembered that where local populations have been e:x.1irpated, introduction of non-local natives
cannot cause genetic contamination.
Custom collection programs should be protective of donor populations by avoiding over-collecting
and by spreading collections across a broad area. These collections should be appropriately labeled,
stored and handled. Volunteers may be employed to collect the plant propagules, while qualified
commercial operations can process the seed and grow the plants.
.
95
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To ensure adequate representation of the genetic resources within the project area, seed or cutting
collections from local plants should be from between 25-50 donor plants. Donor plants should be at
least 100 feet apart and should be found within the Tassajara Creek watershed.
Collection sources should be documented so that in the future, local stock can be distinguished
from non-local or contaminated stock.
Seed suppliers will contract to collect seed from specific locations. They should develop and follow
state-of-the-art techniques for handling, storage, and pre-treatment techniques.
If planting is delayed, the plants produced for the project may have to be repotted to prevent them
from becoming root bound, which will increase the cost of the stock. Purchasing from existing
inventories of suppliers and nurseries' obviates this risk but because existing inventories rarely meet
the standards for local stock, last minute purchases may result in non-local stock.
6.27 Techniques of Local Cutting Collections
Cuttings colleCted from local blackberry, willow and cottonwood donor plants helps contain the
cost of restoration plantings while assuring that genetically local stock is used for project plantings.
Table 4 outlines a schedule of availability for making collections of many of the species required
for the project.
F or each species, all cuttings should be taken from 25-50 donor plants spaced over 100 feet apart
and from locations in the Tassajara Creek watershed. Guidelines for cutting techniques also apply
to pole plantings.
The number of cuttings taken from each donor plant should be approximately equal.
Cuttings or poles may be taken from dormant cottonwood donor plants and directly outplanted.
Pole cuttings may range from two to ten feet in length, depending upon the final planting location.
If soil moisture at the restoration site .is abundant, shorter poles are sufficient. Poles are typically
one to two and one-half inches in diameter at the base. Branches and stubs should be removed and
the top should be pruned close to a lateral bud. Unrooted poles are planted by placing 75 percent of
the length into pre-drilled holes. Holes drilled for pole cuttings need to be only slightly deeper than
the pole. 'While: back-filli..~g the planting hole 'with native soil, care should be taken to remove all air
pockets. Storage procedures are the same as those described for willow cuttings.
Alternatively, cuttings or poles may be taken from local cottonwood donor plants (as described
above) and grown in appropriate containers for future outplanting. A one gallon, citrus pot or five
gallon container can be grown in 12 months rime. In the event cottonwood seedlings are purchased,
both male and female plants should be procured to protect future regeneration. Typically, nurseries
sell only male plants because the female plants produce a very unpleasant odor.
96
'Willow cuttings may be planted directly on site or rooted at a nursery for subsequent planting.
Willow cuttings should be collected from dormant donor plants. Cuttings should be a minimum of
two feet long, one half inch to two inches in diameter at the thick end, consist of non-succulent
material, and should be planted within two weeks of collection. Interim storage should keep the
cuttings cool ~d moist, hut not wet. The cuttings should be stored at least two nights to allow for
drying of the cut ends. The thicker end of the cutting is planted in a vertical hole leaving
approximately one fourth of the cutting in the air, or planting 75 percent. To distinguish between
the thicker or rooting end from the foliage producing end, the root end can be angle cut at collection
time.
\Vatering basins, two and one-half feet in diameter and four inches high should be constructed
around each stem to collect water. Mulch should be applied at a depth of four to six inches, with the
mulch tapered away from the stem to avoid direct contact 'with the root crown. Mulch in contact
with the plant's stem maintains excessive moisture and promotes disease.
97
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Table 1.
Recommended Plant Palette
. .. . p... . ," ..
," ....... ........................-.-.....- ......
. '
TREE SPECIES pROPAGATION WILDLIFE VALUE SLOPE
. .
METHOD ."-. . . STABILITY ,
, ... .. .... . ,
'" .... . ....
Acer macrophy/lum container roosting, cover, food good
Acer negundo container roosting, shade, food good
Aesculus ca/ifornica container roosting, cover, food good
,
Alnus rhombifolia container roosting, shade excellent
Fraxinus latifolia container roosting, shade good
Juglans hindsii container roosting, shade good
Platanus racemosa container roosting, shade good
Populus fremontii container, cutting roosting, cover, shade excellent
Quercus agrifolia container roosting, food, shade good
Quercus douglasH container roosting, food good
Quercus lobata container roosting, food, shade good
Salix hindsiana cutting roosting, cover, food excellent
Salix laevigata cutting roosting, cover, food excellent
Salix lasiandra cutting roosting, cover, food excellent
Sa/ix lasiolepis cutting roosting, cover, food excellent
Sambucus mexicana container roosting, cover, food good
Umbe/lularia californica container roosting, food, shade good
98
Table 1. Continued
.
.,
SHRUB SPECIES PROPAGATION WILDLIFE VALUE SLOPE
.. . METHOD ../::. , STABILITY
... .. ....,..,..:,. :
,.
Baccharis pilularis container cover, food, roosting excellent
ssp. consanguinea -
Diplacus aurantiacus container cover, food good
Eriogonum fasciculataum seed cover, food good
Garrya fremontii container cover, food good
Heteromeles arbutifolia container cover, food good
Lonicera hispidula container food good
Rhamnus californica container cover, food good
Ribes sanguineum container cover, food good
Rosa californica container cover, food excellent
Rubus ursinus cuttings cover, food excellent
Symphoricarpos mollis container food excellent
Symphoricarpos rivularis container food excellent
Vitis californica I container food good
Zauschneria californica container cover, food good
.
.
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ID 7
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116
Table 1. Continued
. , ,
GRASS AND FORB SPECIES PROPAGATION WILDLIFE VALUE ' SLOPE.
FOR ~IPARIAN AREAS ,.,..' METHOD STABILITY .....
Artemisia doug/asiana seed I cover excellent
-
Bromus carinatus seed cover, food good
Efymus g/aucus seed cover, food excellent
Efymus triticoides transplant cover excellent
Eschscho/zia ca/ifornica seed cover fair
Hordeum brachyantherum seed cover, food good
Iris doug/asiana divisions cover fair
Lupinus bic%r seed food fair
Lupinus densif/orus seed food good
Lupinus nanus seed food good
Lupinus succulentus seed cover, food good
Mimu/us cardinalis seed food good
Sisyrinchium bellum seed food fair
Stipa pulchra container, seed food good
This seed mix would be used on side slopes in the riparian area throughout the project area.
100
Table 1. Continued
.
.,
,.
....
..
PROPAGATION
METHOD/RA TEOF
. . ..
APPLlCtHION
WILDLIFE VALUE
. ... ~
GRf-SS A",I?FORBSPECIES
FORFLOOO PLAINTERRACE
.. . .. .......
: ..'::"
..
..:.'.::'.:..::, ':,.. .
, SLOPE
ST ABILlTY.
Achillea mille folium seed I ..
cover, food
good
good
Bromus carinatus seed I 4 Ib.!ac
cover, food
Clarkia elegans seed I ..
cover
fair
E1ymus glaucus seed I 4 lb.!ac
cover, food
excellent
Eschscholzia califomica seed I ..
cover
fair
Gilia capitata seed I ..
Hordeum califomicum seed I 5 Ib.!ac
I Lasthenia glabrata seed I ..
Layia platyglossa seed I ..
cover
fair
cover
good
cover
fair
cover
fair
Linum grandiflorum var. rubrum seed I ..
cover
fair
Linum lewsii
seed I ..
cover
fair
Lupinus succulentus
seed I ..
cover, food
good
good
.
Lupinus densiflorus
seed I ..
food
Phacelia campanularia
Plantago insularis
seed I ..
cover
fair
seed I 30 Ib.!ac
none
excellent year
1
Sisyrinchium bellum
seed I ..
food
fair
* All species noted with the asterisk are available in a combination seed mix known as "California
Native Wildflowers" from Pacific Coast Seed, 7074 D Commerce Circle, Pleasanton, CA 94588,
(510) 373-4417. Six lb.lac of this seed mix should be applied
The seed for the flood plain terrace should be used only on those areas above the creek channel,
maintained for non-irrigated native and annual grasses. This seed mix should not be used on
creek side slopes or the riparian terraces within the project area.
.
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Table 2.
Growth Habits of Plant Species Recommended for Restoration
..
TREE SPECIES COMMON NAME HABITAT: . , ON
..... .. , . .. ... .,
.. .. .... ,. .. . .0" SITE ."
.... .' -- . , ..
.. - ',', ............, .
Acer macrophyllum big leaf maple mesic slopes, shaded banks
Acer negundo box elder riparian
Aesculus ca/ifornica buckeye dry slopes, sunny banks
Alnus rhombifolia white alder riparian, water's edge
Fraxinus latifolia Oregon ash riparian
Juglans hindsii California walnut banks, mid-riparian zones
Platanus racemosa sycamore riparian, bank tops
Populus fremontii cottonwood riparian
Quercus agrifolia coast live oak dry bank tops
Quercus douglasii blue oak sunny, dry bank tops
Quercus lobata valley oak dry bank tops, riparian
Sa/ix hindsiana Hind's willow riparian, water's edge'
Salix laevigata red willow riparian, water's edge
Salix lasiandra yellow willow riparian, water's edge
Sa/ix lasiolepis arroyo willow riparian, water's edge
Sambucus mexicana elderberry riparian, canyons
Umbellularia californica California bay shaded bank tops, north slope,
mid-slope
102
Table 2. Continued .
" .
. .. ..
SHRUB SPECIES ..,. COMMON NAME HABITAT .... ON
. , ., ,. . .. , ,
,. SITE,
'.."....:"....""....' . .:...,.........., '...
Baccharis pilu/aris ssp. coyote-brush banks, terraces
consanguinea
Eriogonum fasciculatum wild buckwheat dry rocky places
Heterome/es arbutifo/ia toyon banks and slopes
Rhamnus califomica coffee berry shaded understory
Ribes sanguineum red-flowering forest, woods
currant
Rosa califomica wild rose mesic forest, riparian
Rubus ursinus California woods, riparian
blackberry
Symphoricarpos mol/is creeping mesic forest, riparian
snowberry
Symphoricarpos rivu/aris snowberry mesic forest, riparian .
Vitis califomica wild grape riparian, mesic slopes
Zauschneria califomica California fuschia banks, slopes
.
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113
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Table 2. Continued
GRASS dANDFORB. SPECIES d
COMMON NAME HABIT AT ON
.... .. SITE'
d.::..... '
Artemisia douglasiana mug wort riparian, moist places
Bromus carinatus California brome dry slopes, woods
E1ymus glaucus wild rye grass shaded woods, mesic slopes
E1ymus triticoides creeping wild rye moist or shaded banks
grass
Eschscholzia californica California poppy grassy, open places
Hordeum brachyantherum perennial wild moist places, meadows
barley
Iris douglasiana wild iris shaded woods, open forest
Lupinus bicolor annual lupine open grassland
I Lupinus densiflorus lupine grassy slopes
Lupinus nanus lupine grassy slopes
Lupinus succulentus lupine grassy slopes
Mimulus cardinalis scarlet stream banks, seeps, riparian
monkeyflower
Sisyrinchium bellum blue-eyed grass mesic grasslands, meadows
Stipa pulchra purple dry banks, terraces
needlegrass
104
Table 3.
Recommended Species for Planting Under Oaks
. ... . .
SHRUB .SPECIES ,PROP.AG,l\ !JQ~HME.THOD
..,
;
Eriogonum fasciculatum seed
wild buckwheat
Heteromeles arbutifolia container
toyon
Rhamnus californica container
coffeeberry
Symphoricarpos rivularis container
snowberry
Zauschneria californica container
California fuschia
I
'.....,.."".",. "'H...""<". ..... ' . ' >.... .'... ., ..' .. .,', '.. ., H . .' .",.,.:,..",'...:c ..' H..'.' .... '.'",H ..'c. ..... H.'t
GF\A$SANo FORB S!':E.GIESH ,YT\"'.., :. .,., ' ,
>C.. ,., :., ., ... ,.
. .. .. ..
Artemisia douglasiana seed
mugwort
Bromus ,carinatus seed
California brome
E1ymus glaucus - transplant, seed
-- I
wild rye
E1ymus triticoides transplant, seed
creeping wild rye
Iris douglasiana container
wild iris
Stipa pulchra container, seed
purple needlegrass
105
115
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Table 4.
Plant A '.Iailability and Schedule of Local Collections
.. .'
TREE SPECIES. PROPAGULE TIMEOFYEAR ,. .. PROPAGULE
... COLLECTED . .. A V AILABILlTY 1,
..
Acer macrophyllum purchase
Acer negundo seed fall local
Aesculus californica seed fall local
Alnus rhombifolia seed spring local, purchase
Fraxinus latifolia seed fall local
Juglans hindsii seed fall local
Platanus racemosa seed summer local
Populus fremontii seep/cutting summer Iwinter local
Quercus agrifolia seed summer local
Quercus douglasii seed summer local, purchase
Quercus lobata seed summer local
Salix hindsiana cutting winter local
Salix laevigata cutting winter local
Salix lasiandra cutting winter local
Salix lasiolepis _. cutting winter local
Sambucus mexicana seed fall local
Umbellularia californica seed winter Ispring local
I Local collections made on site, or at off-site locations within Alameda and Contra Costa Counties if seed
or cuttings are limited.
106
Table 4. Continued
.
SHRUB SPECIES PROPAGULE TIME OF YEAR PROPAGULE
.. .. COLLECTED AVAILABILITY 2
.
--
Baccharis pilularis purchase
ssp. consanguinea
I Cercis occidentalis seed fall local, purchase
Ceanothus integerrimus purchase
Eriogonum fasciculatum purchase
Heteromeles arbutifolia , seed winter local
Rhamnus californica seed fall local
Ribes sanguineum seed summer local, purchase
Rosa californica seed winter local
Rubus ursin us cutting winter local
Symphoricarpos mol/is seed fall local, purchase
Symphoricarpos rivularis seed fall local, purchase
Vitis californica seed fall local, purchase
I
Zauschneria californica seed winter local, purchase
.
2 Local collections made on site, or at off-site locations within Alameda and Contra Costa Counties if seed
or cuttings are limited.
.
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Table 4. Continued
- ---- , .:' -, - -- - . ,- . ... . .... . " . ..
GRASS AND FORB SPECIES PROPAGULE : TIME OF YEAR - .PROpAGULE.
. . . - . . A V AILABILrTy3
H_:H.::::. .:,',:::..::':':..' .:.' .' COLLECTED .':",'
. . I. ' .
--
Artemisia douglasiana purchase
Bromus carinatus purchase
Elymus glaucus seed summer local, purchase
Elymus triticoides transplant winter local, purchase
Eschscholzia californica purchase
Hordeum brachyantherum purchase
Iris douglasiana purchase
Lupinus spp. purchase
Mimulus cardinalis purchase
Sisyrinchium bellum purchase ,
Stipa pulchra purchase
I
3 Local collections made on site, or at off-site locations within Alameda and Contra Costa Counties if seed
or cuttings are limited.
108
Table 5.
Recommended Prohibited Species
. ,.. ... ..... . .. ...
. '. .. .... . . . .. .... .. ..... . ..'.. ..
. '
SCIENTIFIC NAME "., .. , .. COMMON,NAME
. ,. . ..
--
Acacia spp. acacia
Bambusa spp., et al bamboo
Muelenbeckia complexa mattress vine
Robinia pseudoacacia black locust
Eucalyptus globulus blue gum
Ricinus spp. castor bean
Cotoneaster cotoneaster
Hedera helix English ivy
Cytisus monspeliensis French broom
Pennisetum sp. fountain grass
I A run do donax giant reed
Senecio mikianoides German ivy
I
Ulex europaeus gorse
Mesembryanthemum chilensis ice plant
Cortaderia selloana pampas grass
~. ....
Vinca major periwinkle
Pyracantha sp. pyracantha
Cytisus spp. broom species
Tamarix spp. tamarisk
Ailanthus altissima tree-of-heaven
I Nicotiana glauca tree tobacco
109
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Blackberry cuttings should be collected from dormant donor plants. Cuttings should be a minimum
of two feet long, one quarter inch in diameter at the thick end, non-succulent material, and should
be planted within three days of collection. Interim storage should keep the cuttings cool and moist,
but not wet. The cuttings should be stored at least one night to allow for drying of the cut ends. The
thicker end oftbe cutting is planted in a 45 degree angled hole leaving approximately oneJourth of
the thinner end of the cutting in the air. To distinguish between the thicker or rooting end from the
foliage producing end, the root end can be angle cut at collection time. Watering basins and mulch
are not necessary.
6.28 Techniques of Local Seed Collections
Seed from the species currently growing in sufficient numbers (valley oak, coast live oak, buckeye,
California bay, box elder, walnut and ash) should be collected from a minimum of30 donor plants,
spaced at a minimum of 100 feet apart and from locations in the Tassajara Creek watershed. Seed
from maple, walnut, alder and sycamore would require collections in southern Contra Costa or
northern Alameda County since these species are found in low density within the project area.
.
The seed should be properly labeled with date and collection location, and sent to a nursery for
propagation. Care should be taken to avoid donor trees in the vicinity of landscape trees of the same
species, since pollen contamination i1;om the non-local landscape tree is likely.
Seed may also be collected on-site from California wild rose, elderberry and Christmas berry. Seed
and plants should be purchased or collected in nearby locations for the remaining species, which
have limited s~ed sources. Seed for these species can be purchased from suppliers.
In any seed collection, the donor plants should be monitored to determine when the seed is ripe. For
many of the species in the plant palette, Table 4 shows its availability, through either purchase or
local collection. Seed, cuttings and transplants may be collected on site, collected from off-site
locations in southern Contra Costa or northern Alameda County, or purchased. For those species
available for local collections, the propagule type and approximate time of year during which
collections are made is provided.
6.29 Container Planting Techniques
In ungraded areas, tree and shrub planting positions should be scalped clear of annual grasses and
forbs in a circle centered on the planting site. These weeds would otherwise compete for
moisture and sunlight critical to the establishing plants. The scalped area should be five feet in
diameter for trees, and three feet in diameter for shrubs.
Prior to planting, all exotic species should be eradicated within the area to be planted and the
irrigation system should be installed, tested and fully functional.
. Tree and shrub planting holes should be augured prior to planting. Hole preparation promotes
deep root penetration. \\.'h.ere soils are loose and well drained, auguring is not necessary.
110
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Planting holes should be dug to twice the depth and diameter of the plant container (Figure 24).
.
The revegetation specialist may consider the option of using perforated ADS drain pipe vertically
installed, to provide for deep watering of the root systems. If used, the drain pipe should be three
inches in diameter, 30 inches in length, in sound condition with no cracks, and filled with 3/4
inch drain rock, throughout the 30~inchQrain pipe column.
A slow release' fertilizer that will provide supplemental nutrients during the first two years should be
used for all shrub and tree plantings with the exception of blackberry, cottonwood and willow cuttings,
Two time-released fertilizer tablets should be used for each container planting hole. Seven gram 12:8:8
Agriform tablets or equal would be suitable. Application of additional fertilizers should not be
necessary. Fertilizers, especially when app~ied in great quantities, tend to favor exotics.
Backfill in the planting holes should consist of native soil. The revegetation specialist should
review any plans to import soil for revegetation.
On level ground, watering berms (two and one-half feet in diameter and four inches high) should
be built around all container plants larger than liners, Berms around liners should be one and
one-half feet in diameter and three inches high. These berms are needed to prevent water from
running off, and they will settle and erode over time.
.
Planting techniques on slopes differ slightly from plantings on level ground. To accommodate
slope plantings, a small planting terrace is excavated approximately twenty inches wide and
fifteen inches deep. The terrace is sloped slightly to the hill and a four inch berm is built on the
open side to collect water.
All trees and shrubs should be mulched with shredded nitrolized bark mulch, three inches deep
and tapered away from the stem to avoid root rot. The deep mulch is expected to settle. Mulch
inhibits weed growth, conserves soil moisture and is a preferred alternative to plastic weed cloths
or chemical weed control.
The day they are planted, all plants should be 'watered-in', regardless of soil moisture
conditions.
Final planting plans should include specifications addressing inspection of site modifications,
review and acceptance of planting stock, root and top pruning, handling and storage of stock, and
acceptable planting dates.
Optimal planting conditions are when the soil is moist to a depth of twelve inches, usually after
the first fall rain. In a normal season, October is the preferred month. If drought conditions
cannot be avoided, supplemental irrigation should be used to compensate. The physiological .
state of the plants is optimal during the fall and winter, therefore overall restoration success is
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enhanced by adhering to appropriate planting schedules. In addition, a fall planting drastically
reduces the need for supplemental irrigation.
Section 6.30 Seeding Techniques
Seeding with natives provides slope stabilization benefits as well as wildlife habitat. Areas to be
seeded include: the flood plain terrace,oare areas between existing native vegetation, areas
denuded of vegetation through exotics eradication and debris removal; and areas denuded
through grading modification. The optimum season for direct seeding is fall, when moisture,
temperatures and plant physiology are all favorable for establishment. If seeding with natives
outside this biological window is conducted, reseeding may be required.
Proper soil preparation is essential t<? seed establishment. Sites will be evaluated on a case-by-
case basis by a revegetation specialist to determine appropriate procedures. The
recommendations of the qualified soils scientist, described above, should be incorporated at this
time. Soil preparation will include mitigation of compaction and creation of a suitable seed bed.
Seed application alternatives include: broadcast seeding, broadcast seeding with straw, and
hydromulching or hydro seeding. Seed is mixed with 200 Ibs. of slow-release fertilizer (16-20-0)
and applied via the appropriate method. A case can be made to exclude fertilizer if exotics are a
threat to the establishing natives.
If rapid soil stabilization is needed, a nurse crop is included in the seed mix. Plantain (Plantago
insularis) is recommended as a nurse crop because it will not compete with the establishing
natives and is non-persistent. Other nurse crop species could permanently establish in the
community and become a maintenance problem.
Establishment by broadcast seeding is primarily used for native grass and annual species. In the
fall, the soil should be scarified with a rake, after compaction is mitigated through other methods.
Seed and fertilizer may be applied with hand-held spreaders to scarified soil, and the site should
be raked so that approximately one eighth to one quarter inch of soil covers the seed.
Broadcast seeding in the absence of straw should be used in small areas devoid of vegetation.
No irrigation is required if adequate winter rains ensue.
Broadcast seeding with straw mulching should be used in larger areas with moderate slopes (over
30 percent) to stabilize the slope and prevent soil crusting, which hinders germination. Prior to
broadcasting the seed and fertilizer, the soil should be scarified with a rake, followed by raking to
cover the seed with one eighth to one quarter inch of soil. Straw mulch is then applied by hand.
Only certified weed-free straw should be used at a rate of 30 to 50 bales per acre. Straw will
provide some protection against grazing by birds. Irrigation requirements should be determined
on a case-by-case basis during final restoration planning.
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Hydromulching differs from hydroseeding in that the mixture includes a wood fiber mulch. .
Hydromulching should be used in larger areas with steep slopes. The soil should be scarified, and
the seed and mulch broadcast by hydraulic pumping. Irrigation requirements of seeded areas
should be determined on a case-by-case basis during final restoration planning. If seeded at the
proper time of year, no irrigation system should be needed. Hydromulching is significantly more
expensive than broadcast seeding because hydraulic trucks and long hoses are needed to mix and
apply the materials.
Material specifications of a typical application of hydro mulch for a restoration project on a per
acre basis include: 200 lbs. ofa 16-20-0 slow-release fertilizer, 1,800-2,000 lbs. of wood fiber
mulch, 150-200 lbs. oftackifier, 30 to 50 lbs. of nurse crop seed, and brightly colored dye.
Inclusion of the nurse crop may not be necessary ifrapid seed germination is not needed. Final
specifications should be prepared by an experienced revegetation specialist.
Hydromulching specifications should address seed origins, seed pretreatment, fertilizers,
materials specifications, materials handling and storage, certification and warranty period,
contractor performance standards, cleaning of equipment prior to use and equipment
specifications. The revegetation specialist should evaluate the merits of the two step
hydromulching process, which is a California Department of Transportation standard. The
process involves spraying the water and seed mix, followed by mulching. This places
germinating seed closer to the soil and protects seed from drying out in the mulch.
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Seeding rates depend on seed weight, purity and germination. Perennial grasses grow slowly the
fIrst year and take approximately two years to establish a healthy stand. Direct seeding of large-
seeded native grasses is generally adequate at a rate of 15 to 25 pounds per acre. Perennial
grasses respond favorably to nitrogen fertilizers. On bare soil sites or sites relatively free of
exotics, nitrogen may be applied during the fIrst fall. If weed competition is anticipated to be a
problem during establishment, nitrogen application should be postponed to the following season.
Broadcast fertilizers should be applied only to bare soils along with planting or seeding. Since
desired native plants will only uptake small amounts of fertilizer, rates should be appropriate to
the establishing natives. .
6.31 Transplanting Techniques
Transplanting salvaged plants should be encouraged for appropriate species, such as wild
cucumber (Marah fabaceous) and native rhizomatous grasses.
Planting plans should include details oftiming, collection, sizes, handling, storage, planting
techniques and follow-up care.
During construction, all undamaged.wild cucumber (Marahfabaceus) tubers excavated
incidental to construction should be salvaged and stored so they can be replanted within the
project area. Excavated tubers should be stored in the shade, and covered with soil and burlap
which should be kept damp until they can be replanted. Storage may extend over three to four
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months, depending on the construction schedule. The tubers should be replanted in holes at least
one foot in depth, covered with soil and left. unirrigated. These planting holes should be located
within the Zone 3 riparian area. Tubers should be planted at least 10 feet apart, and no closer than
two feet to the next container plant. The number of wild cucumber tubers to be excavated is
unknown, but all reasonable efforts to ~~Ivage them during construction should be made. The
construction crew should be trained to look for them, lli'1d where and how to store them.
Transplants of creeping wild rye should be col1ected in areas where they would otherwise be
destroyed by construction activities. Plugs should be a minimum of four inches square and six
inches deep, with the tops trimmed prior to digging. Salvaged plugs should be replanted the same
day, if possible, or stored in a cool, moist place for a maximum of one day. The plugs should be
thoroughly 'watered-in' the day they. are planted. Irrigation may be required to keep the
transplanted plugs alive, especially through the first summer season. Plug transplantation should
be conducted as soon as the fall ground is cool and wet.
6.32 Areas Expected to Naturally Revegetate
Riparian vegetation is expected to naturally regenerate when cattle and horse grazing along the
creek is discontinued. The freshwater marsh, willow and oak species will show the greatest
response to this change in the management regime. Supplemental restoration plantings of these
species however, may be locally beneficial, particularly when accompanied by exotics
eradication.
6.33 Plant Protection
Grazing will be reduced and eventually excluded from the riparian corridor and tributaries through
the use of alternate watering sources and some exclusionary fencing, as well as zoning changes as
described in the City of Dublin's Grazing Management Plan and the Specific Plan. Excluding cattle
and hors_es from the creek and tributaries will make ~ significant contribution to natural restoration
of riparian vegetation, and ultimately, habitat values.
Protection of establishing vegetation or sensitive areas can be accomplished in a variety of ways,
including educational signing, exclusionary fencing, and pedestrian unfriendly vegetation such as
native blackberry or wild rose. The selection of the appropriate method will depend on the
resource to be protected. Educational signing has obvious merits, but can unfortunately bring
undesirable attention and noise to 'wildlife species that can interfere with breeding and care of
young. Temporary fencing or flagging of plants may be required during critical establishment
periods and at vulnerable locations. An inexpensive and effective fence can be constructed by
stringing rope between posts, in conjunction with signing. Bright orange construction fencing is
very effective. A signing and fencing plan should be prepared in the final planning phase.
Native blackberry and rose thickets can be used to discourage people from entering sensitive
resource areas. Vegetation intended to buffer or prohibit entry should be temporarily fenced until
established.
Plants should be protected from animals by caging only if deemed necessary by the revegetation
specialist in the final planning phase. Oaks may require caging. The horticultural monitor or
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revegetation specialist should be alert to excessive browsing. If damage is detected, cages can be
retroactively fitted to plants. It should be remembered that browsing is a natural process and
should only be discouraged if excessive. If used, cages require maintenance and eventual
removal. Browsing can be reduced by appropriate watering, i.e., not over watering.
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Gopher caging placed below ground should only be specified on replanting locations where the
original plantings suffered extensive mortality due to gophers, or where root damage can be
anticipated.
Staking and guying of trees should be discouraged, especially in the riparian area. Exceptions
include trees adjacent to trails. Those landscape trees requiring staking can be retrofitted once
they demonstrate a need for staking to survive.
Pests and diseases are a natural part of the ecosystem and should be evaluated on this basis by an
experienced professional prior to prescribing any control treatments.
Domestic animals, namely cats and dogs have detrimental effects on wildlife. The EIR for the
Eastern Dublin Specific Plan describes enforcement of leash laws.
6.34 Temporary Irrigation System .
To accommodate the distinct water requirements of plants in the riparian restoration area and
trail landscaping, two separate irrigation systems will be needed. The riparian plantings in the
creek channel area are expected to become self-sufficient three to five years after planting,
therefore a temporary irrigation system will be needed for these plantings. The trail landscaping,
because of the distance to the water table, may require continued irrigation indefinitely and a
permanent irrigation system should be installed if species used are not self-sustaining without it .
No irrigation of the flood plain terrace should be installed, as it should be managed for non- -
irrigated native and non-native grasses.
The irrigation system should be installed, flushed, tested and functional prior to the installation
of the plants. Details of irrigation systems should be included in fmal restoration plans and
should address: water point of connection (POC), adequate water pressure, lists of materials,
sleeving, buried lines, staking lines and water quality. Groundwater pumping for irrigation
should be avoided due to known water quality problems that will impair plant growth.
In most cases irrigation should be supplied by drip systems. Irrigation of the riparian restoration
area should be discontinued once tht? plants are established (approximately two to five years). If
planted on native soils during dormancy, the plants are likely to require supplemental irrigation
for only two or three seasons.
Specifications .for plantiTlg and installation of the irrigation system should include installation of
drip emitters within the planting basin and placement of lines within the project area.
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Small drip systems scattered along ~e creek can be run on battery or solar-operated timers to
avoid the substantial cost of installing centralized systems.
Duration and frequency of irrigation should be controUed by plant water demands and seasonaUy
adjusted to reflect the plants' requirements. The California Irrigation Management Information
System of Sac~amento (C:I.M.I.S.) can be used as a source of information on regional watering
requirements for various species. A maintenance manual that specificaUy addresses irrigation
prescriptions should be developed in order to conservatively aU ocate water resources.
6.35 Salvage and Placement of Woody Debris
Large woody debris that has faUen to the ground, such as tree trunks or large limbs play an
important role in riparian and upland ecology. Insects, reptiles and amphibians use the woody
debris for shelter and nesting habitat, downhill sediment movement is arrested by woody debris,
and its eventual decomposition provides organic material for soils.
Some trees may have to be removed during the construction of the project. Large (greater than
six inches in diameter at the small end) limbs and trunks should be salvaged, bucked into 6-12
foot lengths and salvaged for placement on the upper banks, or at the top of the bank of the
tributaries to Tassajara Creek. Flood control concerns restrict the placement of this woody debris
in Tassajara Creek. Large woody debris needs to be firmly anchored in place to thwart any
attempts to roU or move them into the flood control channel.
Placement details should be developed as part of the final plans and specifications.
6.36 Horticultural Monitoring and Establishment Maintenance
Horticultural monitoring will be conducted as part of permit requirements established bY the
California Department ofFish and Game, the Army Corps of Engineers, and the State Water
Quality Control Board. The purpose of the horticultural monitoring program is to establish
diverse riparian vegetation within a relatively short period oftime, so that the habitat can
subsequently sustain itself in perpetuity. The establishment maintenance period of riparian
projects in northern California typically requires three to five years. The habitat monitoring
program is different in that it focuses on quantitative measurement ofthe vegetation
development, as discussed below.
Horticultural monitoring and maintenance should evaluate and trigger remedial actions
regarding: cause and replacement of mortality, addition of or removal of plant cages, biological
and mechanical erosion control, debris removal, exotic plant eradication, irrigation, species
cultural requirements and treatments, replanting, vandalism repair, protective fencing and
signing. Strict adherence to irrigation and weeding guidelines prepared by the revegetation
specialist will be essential for restoration success. Many restoration failures are explained by
inadequate weeding, and/or excessive and frequent irrigation. The revegetation specialist will
identify any horticultural or other problems.
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Horticultural monitoring, sometimes referred to as site monitoring, is necessary to evaluate plant
health and to identify and correct problem areas. It is a subjective process and relies on the
environmental horticultural expertise of experienced restorationists. If a maintenance contractor
is responsible for establishment maintenance, frequent review by the revegetation specialist is
recommended, starting with overseeing-s-ite preparation and installation, and continuing through
the establishment period.
Because revegetation may be fragmented by phasing with different owners involved in the
distinct phases, it is recommended that a maintenance manual be developed prior to plant
installation. A manual would detail the maintenance procedures and identify the cultural
requirements of the dominant species.
To ensure that subsequent project phases benefit from earlier restoration efforts, the maintenance
manual should be designed to accommodate updating.
Erosion control will influ~nce maintenance activities until the plants are well established and
thriving without artificial irrigation. The revegetation specialist should evaluate local failures and
recommend appropriate remedial actions. In most cases, the area will simply require minor
repairs and revegetation. Severe problems may dictate an engineering solution. Erosion failures
should be evaluated on a case-by-case basis.
Common erosion problems of revegetation projects that may be anticipated include: gullies, rill
and sheet erosion, and bare soil areas. Repair typically includes redirection or dissipation of the
water source, and recontouring of soil, followed by seeding, mulching, or planting.
....,...
If appropriate, the revegetation, specialist will prescribe seeding of eroded areas. The plant palette
and installation guidelines employed in the revegetation phase should dictate species selection.
The use of invasive exotic species should be avoided. Plantago insularis, although not native, is
recommended as a nurse crop for most erosion control situations. As a nurse crop, it establishes
quickly to stabilize soil but will not compete with the native plants.
Removal of trash and litter should be done by hand on a regular basis.
A desirable objective is to remove all exotics prior to planting. This gives the natives the
competitive edge needed to compete with exotics and capture the site. Freshly graded soil from
site preparation provides a perfect seedbed for windblown seed from invasive exotic species. The
success of initial eradication efforts will determine maintenance requirements.
A desirable maintenance goal is to remove exotics before they are allowed to seed or become
well established on the site. Invasion of the restoration areas by exotic species should be noted in
the monitoring reports and prescriptions for removal should be provided. Exotic eradication
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during the maintenance period should emphasize hand remov~ techniques. Native vegetation
should be protected and most exotic seedlings are readily removed by hand.
If used, chemicals should be strictly regulated. The site preparation guidelines provide specific,
control treatments for the dominant exotic species, but the maintenance manual should identify
manual techniques for exotic seedlings. Conservative application of chemicals is discussed in a
previous section.
Irrigation should be provided in such a manner as to facilitate proper root development. The
maintenance goal is to ensure that plants become established so they are independent of the need
for supplemental irrigation after the establishment period. This goal requires that plants develop
extensive root systems that are able to tap groundwater supplies throughout the dry summer
months. The use of deep, infrequent waterings stimulate the plants to develop the extensive root
systems required to meet this goal. If the plants are overwatered, or receive frequent shallow
irrigation, there is no incentive for the plants to develop extensive root systems and their roots
will remain at the surface. .
The maintenance manual should detail specific irrigation prescriptions that are based on the
species, time of planting, method of application and the need to develop deep root systems for
plant establishment.
All temporary irrigation systems should be maintained in a fully functional condition for
approximately five years, regardless of whether the system is still in use. The plants may require
supplemental irrigation in unusually harsh conditions during this period. Irrigation may cease
once the revegetation specialist has determined that the vegetation is self-sustaining. If properly
maintained, temporary irrigation systems may be moved to subsequent project phases after five
years. To ensure that the vegetation is self-sustaining in the absence of irrigation, the site should
be monitored for an addition two years after the irrigation is turned off.
The irrigation system should be monitored and repaired on a monthly basis to ensure that all
plants receive adequate water. Early morning irrigation is required under windy conditions. In
addition, all plants should be monitored for stress and desiccation.
It is strongly advised that maintenance staff use, but not rely on timers, and remain on-site during
irrigation to identify problems. It is critical that staff inspect the plantings frequently to insure
that the irrigation regime is adjusted to reflect changing conditions, and that the system is
functioning as designed.
Oaks are particularly susceptible to root disease, and overwatering can promote disease, since
these species are adapted to dryer conditions. In addition, excessive irrigation promotes
unwanted weeds that must then be eradicated. The revegetation specialist should be consulted
after several fall rains have occurred, to determine if the irrigation can be discontinued until
spring. Established oaks should not be irrigated during summer months.
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Cultural treatments such as fertilization and pest control should be kept to a minimum. It may be
necessary to measure certain site conditions such as soil moisture or weather, in order to
determine cultural treatments.
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Fertilizers should not be necessary, aside from what is administered at plant installation. No
herbicides or pesticides should be allowed tb contact open water, or runoff into the creek. The
use of chemicals in treatment of pests will be restricted.
Common pests and disease that occur naturally in the environment (such as Anthracnose on
native sycamore trees) should be identified as tolerated infestations. Problems that threaten plant
health and vigor should also be identified, and recommended treatment alternatives should be
included.
Integrated pest management should be considered to control problems that threaten plant health
and vigor.
No maintenance is required after the establishment period, except to maintain trails and view
conditions.
Large branches in Tassajara Creek that have the potential to clog downstream culverts may be
removed. Large woody debris however, is beneficial to certain amphibian and insect species, and .
the treatment of such material is described above in the section on large wo~dy debris.
The specific cultural requirements of the tre.e and understory species should be provided in the
maintenance manual.
During the initial revegetation phase", signs should be posted at all possible access points to
prohibit entry or trespass. Fencing may also be necessary. Signs should identify areas as sensitive
and under restoration.
Vegetation intended to provide a buffer or prohibit entry should be fenced until fIrmly
established.
The revegetation specialist will prescribe replanting requirements, including any species
substitutions, numbers and schedules. An inspection should be made six times per year during
the first year after installation. Thereafter, mortality and plant growth and vigor should be
checked a minimum of two times per year until performance standards and establishment goals
are achieved. Table 6 shc.ws the monitoring schedule for the horticultural evaluations and the
quantitative data collection (habitat monitoring). Horticultural visits should be timed to span the
entire year, to evaluate plantings after a large storm event or an especially hot spell during the
summer.
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The flood plain terrace located above the riparian corridor should be managed to support non-
irrigated native, annual grasses and some wildflowers. If the site is properly prepared to support
establishment of the seed mix and seed is applied at the correct time of year, maintenance to
establish the terrace should focus on erosion control and control of especially noxious weeds.
Non-native grasses, although not included in the seed mix, are expected to invade these areas and
should be tolerated as part of the natural--system. Long-term maintenance of the grasses should
emphasize control methods such as mowing twice per year. Mowing encourages the native
grasses and discourages the yellow star thistle and other noxious weeds, while controlling fuel
loads. Disking is not preferred because it favors exotics and promotes soil erosions.
6.37 Habitat Monitoring .
Habitat monitoring will be conducted as part of permit requirements established by the California
Department ofFish and Game, the Army Corps of Engineers, and the State Water Quality
Control Board. A habitat monitoring program is designed to quantify and document
establishment of the vegetation and determine at what point the habitat is self-sustaining.
Quantitative monitoring cSf restoration or mitigation areas should be conducted for five years, or
when all performance standards have been met, to ensure establishment of the restoration
plantings. It should be conducted at a minimum of two times during the first year, and once per
year annually thereafter. A qualified monitor should measure and evaluate survival and native
plant health and vigor. Performance standards should focus on survival, growth and vigor,
demonstrated self-sustaining vegetation, and implementation of remedial actions. Growth and
vigor, typically measured quantitatively through a rating system, should demonstrate a trend
towards healthy establishment. Tree and shrub survival within five years should be at least 85% in
the fifth year. In order for vegetation to demonstrate that it is self-sustaining in the absence of
irrigation, the site should be monitored for an addition two years after the irrigation is turned off.
Remedial actions should have been implemented in a timely fashion.
If a large area of planting is undertaken, representative plots that will result in statistically
representative sampling may be used to reduce monitoring efforts.
Monitoring methods, specifically sampling techniques, should be designed and conducted by a
qualified biologist. Methodology should remain uniform throughout the study to avoid
inconsistencies which may jeopardize the usefulness of the analysis.
Mitigation monitoring parameters may be further defined by regulating agencies and may
include: cover, composition, and plant vigor. Permitting agencies may require additional
performance standards (such as 80 percent cover within three years).
Annual reports summarizing monitoring methodology, findings and analysis should be submitted
to the resource agencies for evaluation.
Table 6 shows the monitoring schedule for the habitat monitoring visits. Quantitative data
collection should occur in the spring and in the fall. If the data is collected the same month of the
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year, from year to year, the analysis will be more meaningful The horticultural and habitat
monitoring visits can be scheduled to coincide.
6.38 Wildlife Surveys
In the stream corridor, there is no obvious need for wildlife surveys as part of the restoration
program, unless required by regulatory ~encies as part of a mitigation plan. Substantial
information developed from reconnaissance and focused surveys prior to and during the EIR
process is available.
If an interpretation program is developed, surveys of avian species could provide detailed
information about the inhabitants of the stream corridor.
6.39 Long-Term Management of Habitat
Once established, the riparian vegetation will mature and unique plant associations will evolve
over time. Because perioqic flooding of Tassajara Creek is inherent in the restoration design,
rejuvenation of these stands over the long-term will occur. Flood scouring, soil preparation and
seed dispersal are the means to achieve rejuvenation of decrepit stands.
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Table 6.
Monitoring Schedule
Restoration or Horticultural Monitoring Habitat Monitoring Annual Report Contingency
Revegetation Area Frequency - Sampling Entire Frequency - Sampling MeasuresfRemedial Actions
Area Representative Plots
Riparian Restoration and During Installation Baseline Data in Year 1 Years 1-5 Replace mortality, control
Mitigation Areas 6 times in Year 1 Spring and Fall in Year 1 exotics, seed at discretion of
Srring and Fall Years 2-5 Fall in Years 2-5 monitor, repair fences. repair
erosion. and other measures at
I, the discretion of the monitor.
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Flood Plain Terrace During Installation None Control erosiQn, control
Four times in Year 1 noxious exotics, seed at
One time in Years 2-5 discretion of monitor, repair
fences, and other measures at
the discretion of the monitor.
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IMPLEMENTATION
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7.1 Implementation and Management
The Eastern Dublin Specific Plan specifies that the City of Dublin will establish a mechanism for
the ownership, management and maintenance of the stream corridor prior to final map approvals.
Improvements.will include stream comaor restoration, flood control improvements and trail
construction to enhance and access the open space network. Though the improvements may be
phased in a number of configurations based on ownership patterns and scheduling, phasing by
the creek reaches would ensure comprehensive treatment and ease the transition between the
reaches. A suggested preferred phasing might be first the lower reach, the middle reach and then
the upper reach. In any event, applicants should demonstrate to the City of Dublin and Zone 7
how the proposed improvements will transition and interface to adjacent properties along the
corridor.
The involved agencies, such as Zone 7 and East Bay Regional Park District may have some
funding earmarked for flood control and trail improvements proposed along the Tassajara Creek
corridor. The City of Dublin Parks and Recreation Master Plan describes funding mechanisms
for acquisition, capital improvements and operations. It also discusses potential cooperative and
city funding sources as well as regulatory mechanisms including: land dedication, in-lieu fees,
user fees, grants, cooperative agreements, bond and tax measures, donations, transfer of
ownership, foundations, land acquisition and development, landscape lighting districts, special
assessment districts, Mello Roos districts, open space and conservation easements, transfer of
development rights, restrictive covenants, performance and specialty zoning and planned unit
development. .
The Eastern Dublin Specific Plan addresses implementation and phasing i~sues of the stream
restoration program. The City of Dublin's--review process for development projects along the
stream corridor may provide for stream corridor land dedication and related improvements (i.e.
flood control modifications, trails, roads, revegetation, landscaping, etc.) as a condition ofproject
approval. To realize the goals of the comprehensive stream restoration program, the stream
portions of the Specific Plan study area should not be fragmented from adjacent development
during the planning and review process.
Development plans along the stream corridor should also be reviewed by East Bay Regional
Parks District, Zone 7 and California Department of fish and Game. In addition, appropriate
regulatory agencies should review and comment on plans as part of their agency's permitting
process. Early involvement of the permitting agencies in project design review is strongly
encouraged. Environmental permits are discussed in a separate section below.
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Preferably, special maintenance of flood control facilities within the stream corridor would be
handled by Zone 7. Special maintenance of regional trail facilities within the stream corridor
should be handled by East Bay Regional Park District. Ownership of the stream corridor should
be dedicated to a public agency and consistent over all three reaches. Long-term maintenance and
management will be accomplished through the development of cooperative institutional
agreements for which complementary management goals and activities will be agreed upon and
jointly financed by participating agencies, including the City of Dublin, East Bay Regional Park
District and Zone 7. Long-term maintenance and management guidelines should be developed
and enforced to ensure that the policies of the Specific Plan and these guidelines for the stream
corridor restoration and preservation are continued by the maintenance agencies.
7.2 Regulatory Compliance
Applicants will be required to comply with federal, state and local environmental regulations.
Early applicant consultation with permitting agencies during the design process is strongly
encouraged. Applicants to the City of Dublin should demonstrate consultation with regulatory
agencies and compliance with environmental permits. Permits in the Tassajara Creek stream
corridor relate to wetlands, erosion and water quality.
'Vetlands fall under the jurisdiction of several regulatory agencies and impacts to wetlands might
require federal, state, and/or local permits or agreements. Prior to the issuance of any
construction permit for actions likely to result in impacts to potential wethmds onsite, the
principle actions would include:
Army Corps of Engineers Clean Water Act Permit
California Department ofFish and Game Consultatic)ll
State Water Quality ControfBoard Certification or Waiver
7.2.1 Armv Corps of Engineers
The Army Corps of Engineers (ACOE) has jurisdiction over a variety of habitats, including
wetlands and waters of the U.S. that occur within the City of Dublin. Under Section 404 of the
Clean Water Act, wetlands are defined as those areas inundated or saturated by surface or ground
water at a frequency and duration sufficient to support and under normal circumstances do
support a prevalence of vegetation typically adapted for life in saturated soil conditions.
\Vetlands generally include swamps, marshes, bogs and similar areas, as well as seasonal
wetlands that are only inundated for at least a specified time period during each year, defined by
a percent of the growing season (12.5% of the 250-day growing season), which may vary with
site conditions. To be classified as a wetland, a site must meet wetland soils, vegetation and
hydrology parameters as defined in the 1987 manual. Waters of the U.S. include navigable
waters, waters of the U.S. subject to ebb and flow of the tide susceptible to interstate commerce,
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impoundments of waters, tributaries. of waters, isolated waters, springs, intrastate lakes, rivers,
streams, mudflats, sandflats, wetlands, sloughs, prairie potholes, wet meadows, playa lakes,
natural ponds, and territorial seas that the use, degradation, or destruction of could affect
interstate foreign commerce.
Projects that include potential dredge or fill impacts to waters of the U.S. and adjacent wetlands
must be reviewed by the Army Corps of Engineers pursuant to S 404 of the Clean Water Act of
1972. Activities that require a notification or a permit from the Army Corps of Engineers include
discharge of dredge or fill material, excavation and disposal activities in waters of the U.S.
Aggregate wetland impacts (defined as dire~t fill or indirect effects of fill) of less than one acre
do not require an Individual 404 Permit. Certain activities in wetlands or "waters" are
automatically authorized, or granted a General Permit which allows the filling of wetlands where
impacts do not exceed one acre. The Army Corps of Engineers assumes discretionary jurisdiction
over proposed impacts which total between one and ten acres. In such cases, the Army Corps of
Engineers can issue either a Nationwide or an Individual Permit. The Army Corps of Engineers
has mandatory jurisdiction over proposed impacts often acres or more (i.e., an Individual Permit
would be automatically required).
Projects which require less than one acre offill of wetlands or waters of the U.S. and which meet
the conditions of the permit would be expected to qualify for a general or Nationwide permit.
The need for mitigation and monitoring is determined by the specific type of permit required.
Once a development plan has been developed, notification should be made to the Army Corps of
Engineers district office in San Francisco, in accordance with S 330.7 (Notification Procedures)
of the Corps of Engineers Regulatory Program Regulations and a jurisdictional determination
requested. Such notification should include the name, address, and phone number of the
applicant, a brief description of the proposed work, its purpose, a formal delineation of the
wetlands/waters of the U.S. onsite, the total acreage of jurisdictional habitat to be affected, and a
conceptual outline of mitigation measures, ifrequired. Upon receipt of this notification, the
Army Corps of Engineers has 15 days to issue a public notice to other interested agencies and
local interest groups. The comment period typically lasts 15-30 days, depending on the nature of
the proposed activity. The Army Corps of Engineers will consider all comments and consult \\lith
other federal agencies, if appropriate. The District Engineer may ask the applicant to provide
additional information or data before making his or her fmal decision on whether or not to issue a
permit. Prior to the issuance of a Nationwide permit by the Army Corps of Engineers, the
applicant is required to obtain a water quality certification or waiver from the Regional Water
Quality Control Board (see below).
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The Army Corps of Engineers Individual and Nationwide permitting process relies upon input
from other state and federal agencies, including the U.S. Fish and Wildlife Service for protection
of federally listed plant and wildlife species, the State Historic Preservation Office for protection
of historic structures, the local office of the Regional Water Quality Control Board for issuance
of a waiver or certification for the proposed project, and the California Department ofFish and
Game for protection of state-listed plantand wildlife species. The Nationwide permit is not valid
unless all appropriate agencies have been notified and a water quality certification or waiver is
secured.
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7.2.2 California Department ofFish and Game
The California Department of fish apd Game has jurisdiction over plant and animal species
recognized by the California fish and Game Commission as rare, threatened or endangered (RTE
species) as well as wetland habitats and its commenting authority over CEQA documents. CEQA
requires mitigation measures for significant impacts and California Department ofFish and
Game is the state agency responsible for impacts to plant, fish and wildlife resources. It should
be noted however, that many actions that produce impacts to creeks and drainages, and the
resources dependent upon them are not subject to any discretionary action under CEQA or any
other regulation.
Wetland Impacts Regulation The Fish and Game Commission, in recognizing that wetlands .
provide significant and essential habitat for a wide variety of important resident and migratory
fish and wildlife species, has clarified its policy to protect, preserve, restore, enhance, and expand
wetland habitat in California. Furthermore, it is the policy of the Commission to strongly
discourage development in, or conversion of wetlands. The Commission therefore opposes
wetland development proposals unless, at a minimum, project mitigation assures there will be
"no net loss" of either wetland habitat values or acreage.
The California Department ofFish and Game normally comments on any proposed actions
resulting in significant direct impacts to biological resources through the CEQA review process,
when issuing a Streambed Alteration Agreement (described below), and when reviewing during
the Water Quality Control Board Certification or Waiver process (as part of the 404 permitting
by the Army Corps of Engineers, described below). 'When a specific project is proposed,
mitigation measures for impacts to wetlands should be included as part of the project. In order of
preference, the regulatory agencies recommend the following types of mitigation: 1) avoidance
of impacts through project redesign and/or relocation, 2) minimization of impacts, and 3)
compensation for resource losses. In order of preference, compensation (widely referred to as
"mitigation") would include 1) onsite in-kind replacement of habitat, 2) off site in-kind
replacement, and 3) mitigation banking.
.
126
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.
.
.
) /}~r
./....
1601-3 Streambed Alteration Agreement The other instrument by which California Department
offish and Game has regulatory oversight for actions which might result in impacts to the
state's plant and wildlife resources is via the requirement for a 1601-3 Streambed Alteration
Agreement for any project that will substantially divert or obstruct a stream, change the bed,
channel or bank, change the natural flow, or use any material from the streambeds. Plans will
again be reviewed for compliance with the Department's standard for a 100 foot setback. The
Department has a no-net-Ioss wetland policy, hence requiring mitigation for affected wetlands.
Securing the 1600 Agreement requires consultation with California Department ofFish and
Game staff, completion of an application and fee, and preparation of mitigation requirements if
impacts are unavoidable. Monitoring may be required if mitigation is a condition of the
agreement. Unlike the Army Corps of Engineers, California Department offish and Game may
require mitigation for impacts to jurisdictional habitats ofless than one acre. for example, if
removal of riparian vegetation for a stream crossing is unavoidable, California Department of
fish and Game will typically require the replacement of riparian species at a 3:1 ratio, and
mitigation of habitat area at a minimum of 1:1 ratio. The fee for the Streambed Alteration
Agreement is based upon the value ofthe improvements made in the project. No public review is
provided for in the 1601-3 Agreement process and it is important to note that California
Department offish and Game does not have the discretion to deny an application for a
Streambed Alteration Agreement if all the requirements for the Agreement have been met.
7.2.3 State Historic Preservation Office
The State Historic Preservation Office (SHPO) has authority over historic properties. Projects
which require CEQA documentation or permitting by the Army Corps of Engineers trigger
oversight by SHPO. SHPO makes a determination on whether historic properties occur within a
proposed project area. The project applicant directs correspondence to SHPO via the appropriate
Information Center to determine whether historic properties occur within the project area. For
projects in Dublin, inquiries would be made to the Information Center at Sonoma State
University. If no historic properties occur within the project area, a letter to that effect is sent to
the permitting agency by the Information Center. If historic properties do occur within the
project area, the Information Center will send a letter describing the historic properties and
requirements for mitigating impacts to the property. SHPO should be notified by the project
applicant when submitting a permit application or notification to the Army Corps of Engineers.
7.2.4 State 'Vater Qualitv Control Board Certification
Pursuant to ~ 401 of the Clean Water Act, any applicant for a federal permit to conduct any
activity which may result in any discharge into navigable waters must provide a certification or
waiver from the California Regional Water Quality Control Board (RWQCB) that such discharge
will comply with the Clean Water Act (R\VQCB, 1988). Projects that would result in discharges
into waters of the U.S., but qualify fpr certain Nationwide Permits also require state water quality
]27
certification or waiver. The Water Quality Control Board has a no-net-Ioss wetland policy in .
effect, and in recent years the Board is enforcing this policy, i.e. requiring mitigation for all
impacts.
Upon receipt of notification from the applicant, the Anny Corps of Engineers might issue a
public notice for review. However, a separate application should be made directly to the Bay
Area Regional Water Quality Control Board by the applicant. The application includes a project
description, quantification of jurisdictional impacts, mitigation and monitoring plans as
appropriate, site maps and a fee. If the Board fails or refuses to act on certification requirements
within a reasonable time (e.g., 60 days after receipt of notification from the Anny Corps of
Engineers), the certification requirement is waived and the proposed action may proceed without
conditions. The Board may elect to issue a waiver. If the Board issues a water quality ,
certification which includes special conditions, the District Engineer will add these conditions to
the Permit. The fee for the certification or waiver is $500.
7.2.5 Regional- Water Qualitv Control Board - NPDES and Reclaimed Water Permits
For any development exceeding five acres, a National Pollutant Discharge Elimination System
(NPDES) permit is required from the Regional Water Quality Control Board. The City of
Dublin, in turn, will require the state permit prior to issuing approval of grading and
improvement plans. However, all developments regardless of size, require the approval of the
City of Dublin Public Works Department, which requires erosion control and the installation of .
Best Management Practices (BMPs). Any development should expect to use approved BMPs
both during construction and as a permanent part of the development infrastructure. The BMPs
are planned in the preparation of the project's Storm Water Pollution Prevention Plan (SWPPP),
which must be approved by the City of Dublin prior to the start of construction. Among the
requirements established by the City of Dublin Ordinance No. 52-SZ, ~stablishing Requirements
for Protection of Watercourses, is that a written permit is required prior to discharging into or
connecting any pipe or channel to a watercourse; depositing, planting or removing materials from
a watercourse including its banks; altering any structure in a watercourse; and causing flow to be
diverted.
The Regional V/ater Quality Control Board may also require permits of the application of
reclaimed water. Zone 7 is also involved in the review process.
128
.
~
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.
.
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J "iD
APPENDIX A REVEGETATION SCHEDULE
.
.
.
.-....;_...:..'.....:.'-,........:...-<~.~t..:-'.,__...
Revegetation Schedule - Scheduling of Project Tasks and Components
Task
PLANNING PHASE
Project Management
Preparation of Preliminary
Mitigation Plan
Detailed Analysis of Site Conditions
Land Acquistion (lor Mitigation)
Preparation of Final Mitigation Plan
Pormitting (Mitigation PI,m Component
Only)
II/I
I
'.,', '
Components
Administration
Coordination
Progress Reports
Project Description
Mitigation Goals and Objeclives
Final Success Criteria
Proposed Mitigation Sites
Implementation Plan
establishment Period Maintenance
Monitoring Program
Air Photos
Surveying
Monitoring Program Design
Soil Sampling
Monitoring Well Installation
SUbstrate Analysis
Groundwater (Piezometer) Moniloring
Slope and Aspect Analysis
Hydrologic Analysis
Project Description
Mitigation Goals and Objectives
Final Success Criteria
Proposed Mitigation Siles
Implementation Plan
Establishment Perio<J'Mainlenance
Monitoring Program
COE
COE 404 Permit
USPNS Coordination
RWaCS Permit
CDF&G 1601-03 Permit
EP A Coordination
County
City
Commissions
Year I Year I~'I' Year I Year I Year
-6 I -5 I ',-4 -3 -2 I -1
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I Preparalion 01 Bid Documents
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Cons1ruction Scheduling
(Revegetation)
I Experimental Testing or Pilot Projects
I IMPLEMENTATlON PHASE
I Projoct Management
I Site Preparation
lq~
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Components
! Grading ana Cleaflng Plan
! (Habitat Mlligation Components _
I including Native Plant Protection)
I Site Preparation, Exotic Eradication and
Phase I Revegetation (Groundcover) and
Erosion Control Installation Plans and
Contract Soecificatlons
Irrigation System Design
I Phase II Revegetation (Woodyt'tant)
Installation Plans and Contract
Specifications
Sequencing of Work Components
\...oordination with Nursefles for
Custom Seed and Plant Collection
and Propagation
Coordination with Engineers
\...oordinalion with other Contractors
and Suopliers
..'.'...-...........". ...........'.-.,.:...;'...
I Administration
I Coordination
1 Progress Reporls
I Final (Rough) Grading/Drainage
Native Plant Protection
I Plant Protection Site Inspection
I Non-organic Debris Removal
Vegetative Material Clearing/Removal
I Chipping/Storage of Mu!ch
Salvage/Storage of Logs
Salvage/Stockpiling of Topsoil
IWeed Control in Stockpiled Topsoil
Preolanting Weed Control
Exotic Plant Control/Removal
I Pest Control
I Ripping and Discing
Soil Scarification
Addition 01 Soil Amendments
Imporl Topsoil
Placement ofTopsoil
Final (Finish) Grading/Drainage
Grading Site Inspection
Revegetation Site Inspection
.
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Task
I Erosion CDntrol and Bank/Slope
Protection
I
(enCing 01 Revegetation Sites
j
IP"" P'oc""m,,, - G"""",w,,,
I
Plant PrO(;urement - YJO()Ijy Plant
Materials
I
I
!Irrigation System - Groundcovers
rrrigation System - Woody Plants
\ Plant Installation and Plant Protection
- Groundcovers
PlantlnS1allation and Plant Protection
-WO()ljy
) ~/'?
'.Components','
H yd r omulc h i ng/H yd rose ed I n g
Erosion Control Materials
Erosion Comrollnstallatlon
Biolechnical Streambank Protection
Erosion Control Site Insoection
Cost of Fencing Malerials
Ditching for Below-ground Fencing
Installation of Fencing
Purchase of Seed
Custom Seed Collection
Seed Processing
Seed PaCkaging and Storage
Ordering 01 Plant Materials
Custom Seed Co/leclion
jContracl Growing of Nursery Stock
jlnspection 01 Nursery Stock
I Collection and Handling of Cuttings
ITransponalion 01 Piant Materials
I Above-gound Temporary Irrigation System
I Above-gound Temporary Irrigation System
I Below-ground Temporary Irrlgalion System
I Installation of Wells, Pumps, Hookups
I Seed Mixing and Measuring
Installation of Temporary Groundeovers
Installation 01 Permanent Groundcovers
I ReceiptlStorage of Plant Malerials
I Flagging of Planting Locations
Tillage (Auguring)
Installation 01 Woody Plant Malerials
Fertilizing
I Purchase/Fabrication of Plant Protection
Construelion at Walering Basins
Installation of Plant Protection
Purchase 01 Mulch
Installation of Mulch
Revegetation Site Inspeclion
Documentation of As-buill Condilion
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APPENDIX B SPECIAL SUBMITTAL
REQUIREMENTS
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CITY OF DUBLIN
CHECKLIST OF SPECIAL SUBMITTAL REQUIREMENTS FOR
PD REZONE HYDROLOGY AND HYDRAULICS
FOR PROJECTS ADJACENT TO T ASSAJARA CREEK AND ITS
TRIBUTARIES
Note: This submittal checklist is.intended to supplement the City of Dublin's Checklist of
Submittal Requirements for PD Rezone. Items already included in the City's current
checklists are not repeated in these Special Submittal Requirements. The special
submittal items are arranged by the title of the submittal. This checklist is intended to
assist applicants in the preparation of submittal documents relating to the stream corridor,
and to facilitate the City's project review process. Submittal documents can draw from
the information and guidelines set forth in the Eastern Dublin Comprehensive Stream
Restoration Program (hereinafter referred to as the Stream Restoration Program, or SRP).
References to the Stream Restoration Program are made by section number. The
requirements for each parcel should be determined on a case-by-case basis and will
depend on the location, site conditions and proposed improvements. It will be the
responsibility of the applicant to work closely with City staff and other regulatory
agencies to determine which documents should be prepared.
On a case-by-case basis, a City Planner will place a checkmark next to the information
required for submittal. The City Planner will need to coordinate certain submittals, such
as hydrologic analysis with the Department of Public Works. Applicants may consider
cooperating with adjoining owners for some of the following studies.
Topographic Map
A Topographic Map of the Tassajara Creek corridor (extending 150 feet beyond the top
of bank on both sides of the channel, including applicable tributaries) is required. It also
forms the basis for HEC- 2 (or HEC-RAS) modeling, development of a channel slope
profile, mapping hydrologic and other setbacks, and grading. Since the channel is often
narrow and the map will be used as a base map for detailed planning, the scale should be
no less than 1 "=40' and a contour interval of no less than five feet. The map will provide
adequate contour detail to clearly show the location of the creek center line, top of bank
for low flow line, top of bank for flood plain, and toe of bank for flood plain. The map
will delineate areas of slope bank instability, areas of existing erosion and erosion
potential, and the type and extent of existing man-made improvements including stream
crossings, drop structures, bank stabilization treatments, rubble, etc. (see SRP sections
4.1,4.6)
Flood Control Modeling
HEC-] modeling will be required or existing flood flow data will be provided by the City
of Dublin or Zone 7 of the Alameda County Flood Control and Water Conservation
District (Zone 7) to serve as the basis for the flows utilized in HEC-2 flood conveyance
modeling. (see SRP sections 4.1, 4.2, 4.6)
]
HEC-2 modelin~ of existing conditions of the reach being developed (and adjacent
reaches) is required by the City of Dublin and Zone 7. The model is especially detailed .
where there are bends, bridges, channel narrowing, or other elements which tend to
constrict or expand the flow, where ther~ are low banks over which a flood may spill onto
adjoining lands, or other locations as requested by the City of Dublin or Zone 7. The
model is used to evaluate flood conveyance capacity and rates of flow under various
hydrologic conditions so as to pinpoint reaches of concern and the degree of the existing
problem. (see SRP sections 4.1, 4.2, 4.6)
HEC-2 modeling of post-development conditions of the reach being developed (and
adjacent reaches) is required by the City of Dublin and Zone 7. The model requires
detailed topographic information of the channel with frequent cross-sections at, above
and below areas of constriction; typical reaches; and other locations as requested by the
City of Dublin or Zone 7. The model is used to evaluate flood conveyance capacity and
rates of flow under various hydrologic conditions. The key function of the channel is to
be able to contain and convey flood flows up to and including the 1 DO-year design flood.
The applicant needs to develop a concept of what channel alterations are appropriate to
meet flood. conveyance, public access, safety, aesthetic, and restoration objectives in
order to create an appropriate HEC-2 model. This may be a several step reiterative
process involving repeated consultations and communications with the concerned
agencies. Reaches of the stream corridor being considered for ownership by Zone 7 will
need to be made to conform to the requirements for the character and dimensions of the .
channel as specified in the Alameda County Flood Control and Water Conservation
District's Hydrology and Hydraulic Criteria Summary for Western Alameda County.
Some aspects of the design in the area being considered for ownership by Zone 7,
particularly aspects related to habitat and aesthetics, may need to be negotiated with and
between the City of Dublin, Zone 7, and the California Department ofFish and Game.
(seeSRP sections 3.1.1, 3.1.3,4.1,4.2,4.6)
Channel Stability Study
A Channel Stability Study ofTassajara Creek is a likely requirement of either the City of
Dublin or Zone 7 to demonstrate the inherent stability of the overall channel. A
preliminary study has indicated that this may be a problem in several reaches. A detailed
analysis of the channel slope and bankfull discharge will likely be required to determine
if the Tassajara Creek channel can be altered safely. Other conditions of approval may
result from this study. Note, that should channel alteration be approved, geotechnical
studies of streambed and bank materials will be required to ascertain the need for and
placement of erosion protection measures. (see SRP sections 3.1.3,4.4,4.6)
For help in understanding this information, please contact:
PLANNING DEP ARTMENT STAFF
CITY OF DUBLIN
100 CIVIC PLAZA
DUBLIN, CA 94568
(510) 833-6610
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CITY OF DUBLIN
CHECKLIST OF SPECIAL SUBMITTAL REQUIREMENTS FOR
TENTATIVE AND FINAL SUBDIVISION MAP
FOR PROJECTS ADJACENT TO TASSAJARA CREEK AND ITS TRIBUTARIES
Note: This submittal checklist is intended to supplement the City of Dublin's Checklist of
Submittal Requirements for Tentative SUbdivision Map (T. Map). Items already included in the
City's current checklists are not repeated in these Special Submittal Requirements. The special
submittal items are arranged by the ~tle of the submittal, and may be included in Item 12 Special
Information of the T. Map Submittal Requirements. This checklist is intended to assist applicants
in the preparation of submittal documents relating to the stream corridor, and to facilitate the
City's project review process. Submittal documents can draw from the information and
guidelines set forth in the Eastern Dublin Comprehensive Stream Restoration Program
(hereinafter referred to the Stream Restoration Program, or SRP). References to the Stream
Restoration Program are made by section number. The requirements for each parcel should be
determined on a case-by-case basis and will depend on the location, site conditions and proposed
improvements. It will be the responsibility of the applicant to work closely with City staff and
other regulatory agencies to determine which documents should be prepared.
On a case-by-case basis, a City Planner will place a checkmark nex't to the information required
for submittal. The City Planner will need to coordinate certain submittals, such as hydrologic
analysis with the Department of Public Works.
Written Statement (TENTATIVE AND FINAL MAP)
A Written Statement that the proposed application is consistent with the Eastern Dublin
Comprehensive Stream Restoration Program is required.
Tentative Map (TENTATIVE AND FINAL MAP)
Existin~ Topographv and Improvements should show the location of the creek center line, top of
bank for the low flow line, top of bank for the flood plain, and toe of bank for the flood plain.
Areas of slope bank instability and areas of existing erosion and erosion potential should be
delineated. The location, type and extent of existing man made improvements, including stream
crossings, drop structures, bank stabilization treatments, rubble, etc. should be delineated. (see
SRP sections 3.4, 4.1, 4.6,6.16)
Locations and descriptions of significant habitat features such as wetlands, tributaries, aquatic
habitat, riparian habitat, large stands of exotics, wildlife nests or significant wildlife habitats, and
unique conditions that constrain the site should be shown. The locations and descriptions of these
features should be prepared by a qualified biologist. (see SRP sections 6.2, 6.5, 6.6, 6.19)
Proposed Improvements (TENTATIVE AND FINAL MAP)
Proposed Improvements should be described in the submittal including: proposed recreation
sites, trails (see SRP section 5.2 and Figures 3,4,5,6, 7, 8), stream crossings (see SRP section
5.3 and Figures 6, 7, 8), and trail amenities (see SRP sections 5.2.5, 6.9, 6.11, 6.12), as well as
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typical trail cross section and location for local trails (see SRP section 5.2.2 and Figures 3, 4, 5, .
6, 7, 8, 10, 11 ), regional trails (see SRP section 5.2.1 and Figures 2, 3, 4, 5, 6, 7, 8, 9),
maintenance r,?ads (see SRP section 5.2 and Figures 3, 4,5,6, 7,8,9, 10) and maintenance
access (see SRP section 5.2). The submittal should show proposed grading in the low flow
channel and within the flood plain, engineering and bioengineering treatments, removal of rubble
(see SRP sections 3.1.1, 3.1.3, 4.1, 4.2, 4.6, 5.5, 6.3, 6.4, 6.16), structure setbacks and wildlife
setbacks (see SRP sections 4.6,5.1, 6.1-and Figures 1,3,4,5), private development buffer (see
SRP section 5.2.1 and Figures 3, 4) adjacen~ to regional trail, and development interface (see
SRP section 5.4 and Figures 6, 7, 8, 12, 13, 14). Show both existing and proposed: creek center
line, top of bank for low flow line, and top of bank and toe of bank for flood plain. (see SRP
sections 3.1.1, 3.1.3, 4.1, 4.2, 4.6)
Accompanying Data and Reports (FINAL MAP)
Soils Report should show areas of existing and potential instability within the flood plain and
should include soil test results for agriculture suitability for restoration plantings. (see SRP
sections 3.3.6, 4.4, 4.5,6.17)
Site Color Slides (TENTATIVE MAP)
Color Slides should show representative creek conditions, including the low flow channel, flood
plain terrace, vegetative cover, stream crossing, drop structures, existing bank treatments, rubble,
and large areas of bare soil.
Special Information (FINAL MAP)
Specimen Tree Protection should include provisions for tree protection including, accurate
locations of trees to be removed and saved, species, diameter at breast height (DBH), contractor
restrictions and equipment requirements. The submittal should also show proposed grading and
structures near trees, including cutting of roots in the least damaging manner, preventing the
storage of materials and equipment around protected trees, avoiding changes in drainage patterns
around trees, cultural treatments, construction monitoring by a qualified arborist, and other
protection measures. Mitigation of removed trees may be shown in the Creek Restoration Plans.
(see SRP sections 6.5, 6.14) -
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A Biological Corridor Connections Map prepared by a qualified biologist is required, showing
on a map at approximately 1 DO-scale, the north-south corridor connections along Tassajara Creek
and the east-west biological corridor connections from Tassajara Creek to open space lands via
its tributaries. The width of the corridor at regular intervals and at constrictions should be
specified, existing barriers to wildlife movement, proposed impediments (improvements and land
uses) to wildlife passage and mitigation of impediments, such as: placement of culvert under
road crossing, fencing to funnel wildlife or plantings. Any proposed fencing within the stream
corridor or its tributaries that could restrict or impair free movement of wildlife, or that may be
used to funnel "wildlife movement into safe passage and away from roads or other hazards should
be shown, with a description of its type and location. (see SRP sections 6.1, 6.2, 6.10)
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Creek Restoration Plans (mitigation and/or habitat restoration) at 50-scale or less should include:
restoration goals, equipment requirements, proposed earthwork, proposed engineering and
bioengineering structures, dewatering, drainage treatment, clearing, debris removal and disposal,
exotics eradication, soil stockpiling, soil treatments, site preparation, planting, seeding,
transplanting, irrigation, establishment maintenance, contractor access and staging areas,
sensitive areas protection provisions, construction precautions and restrictions, site clean up,
qualifications of contractors, constructIon supervision, contingency plans, scheduling and
phasing. (exotics eradication, plantiI).g, seeding, irrigation, monitoring and landscaping plans are
described below. General elements are referenced in SRP sections 6.4,6.8,6.14,6.16,6.17)
Exotics Eradication Plans should include: target exotic species, location and protection of sensitive
resources, man.ua1, mechanical and chemical treatments, target plant size, number of applications,
regrowth, exotic seed control, schedule and climatic constraints, safety precautions, and if
chemicals are used, compliance with Federal, State and local water quality regulations, list of
approved chemicals, application specifications, disposal of spent containers, requirement for
Licensed Pesticide Applicator or Pest Control Advisor. (see SRP section 6.15)
Planting and Seeding Plans for Tassajara Creek and its tributaries should include: planting of
stock, densities, procurement procedures, provisions for species substitutions, seed pretreatment,
soil pretreatment, storage and handling of plants and seed, planting and seeding methods,
watering in plants, areas expected to revegetate naturally, and human and animal protection. (see
SRP sections 6.2, 6.18, 6.20, 6.21, 6.22, 6.24, 6.25, 6.26, 6.27, 6.28, 6.29, 6.30, 6.31, 6.32, 6.33,
6.35) Include test results to support restoration plantings for: soils testing for agriculture
suitability and groundwater depth information (either from testing or inferred by existing
vegetation). (see SRP sections 6.17, 6.19, 6.23)
Since Irrigation will in most cases be temporary, irrigation installation can be provided as a
design-build, however applicant should show irrigation type, water pressure, and provisions for
point of connection and removal of temporary system. (see SRP section 6.34)
Establishment .Maintenance and Monitoring Procedures should be provided, addressing warranty
period, weeding procedures, erosion control, irrigation regime, maintenance of the irrigation
system, procedures for cessation of irrigation, debris removal, replanting and reseeding, cultural
requirements and treatments appropriate to native plantings, site protection, responsible party and
contingency measures. (see SRP sections 6.36, 6.37, 6.38, 6.39, 7.2)
Copies of Permits from California Department ofFish and Game and Army Corps of Engineers,
permit conditions and performance standards should be provided. Ifhabitat mitigation is
included within the stream restoration corridor, this should be clearly represented to the City of
Dublin. (see SRP sections 6.7, 7.2)
Landscaping Plans Adjacent to Tassajara Creek or its tributaries showing: structure setbacks,
wildlife setbacks, private development buffer adjacent to regional trail, screening with vegetation
and development interface should be shown. Planting zones, species, propagule type, size of
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stock, provisions for species substitutions, soil pretreatment, planting and seeding methods,
watering in plants, human and animal protection should be shown or described. Include test .
results to support landscape plantings for: soils testing for agriculture suitability. Establishment
maintenance procedures addressing weeding procedures, erosion control, irrigation type,
irrigation regime, debris removal, cultural requirements and site protection should be described.
(see SRP sections 6.8, 6.9, 6.11. 6.12, 6.13, 6.17, 6.19, 6.20, 6.34)
For help in understanding this information, please contact:
PLANNING DEPARTMENT STAFF
CITY OF DUBLIN
100 CIVIC PLAZA
DUBLIN, CA 94568
(510) 833-6610
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RESOLUTION NO. - 96
A RESOLUTION OF THE CITY COUNCIL OF THE CITY OF DUBLIN
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.PROVING THE EASTERN DUBLIN COMPREHENSIVE STREAM RESTORATION PROGRAM
AND THE TASSAJARA CREEK LOWER REACH IMPLEMENTATION PLAN
WHEREAS, the City of Dublin adopted the Eastern Dublin General Plan Amendment and Specific Plan
on May 10, 1993 and the Dublin voters approved the Eastern Dublin General Plan Amendment and Specific
Plan on November 2, 1993; and
WHEREAS, the Final Environmental Impact Report (FEIR) for the Eastern Dublin General Plan
Amendment and Specific Plan contains Mitigation Measure 3.7/12.0, and the Eastern Dublin Specific Plan
contains Action Program 6F that requires the City to prepare and approve a comprehensive stream corridor
restoration program for the Eastern Dublin General Plan Amendment area; and
WHEREAS, the Eastern Dublin Comprehensive Stream Restoration Program (Stream Restoration
Program) implements Mitigation Measure 3.7/12.0 ofthe FEIR and Action Program 6F of the Eastern Dublin
Specific Plan, and is consistent with the policies and action programs of the Eastern Dublin General Plan
Amendment and Chapter 6 - Resource Management of the Eastern Dublin Specific Plan to the extent that the
guidelines and standards of the Stream Restoration Program will promote the restoration, enhancement and
stabilization of Tassajara Creek and its tributaries; and
WHEREAS, the Stream Restoration Program shall be applicable to the Eastern Dublin General Plan
Amendment area and shall be enforced for all Eastern Dublin rezoning and tentative map/final map
applications; and
WHEREAS, the City of Dublin shall be the ultimate authority for determining and implementing
.ropriate guidelines for stream restoration; and
WHEREAS, the Stream Restoration Program includes recommended guidelines and standards for
stream restoration, and the City of Dublin may apply some flexibility when implementing these guidelines and
standards and allow some guideline moditlcations and negotiations only if these changes meet the intent of the
Eastern Dublin Specific Plan goals, policies and action programs, and the Stream Restoration Program criteria
and guidelines; and
WHEREAS, trails, creek crossings and maintenance road extensions, as shown in the Stream
Restoration Program, can be interrupted as a result of private property, topographical or other site constraints, as
long as trail/maintenance road ingress and egress points are provided at these points of interruption; and
WHEREAS, the Tassajara Creek Lower Reach Implementation Plan sets forth the framework for
ownership, maintenance, and operation responsibilities for the portion of the Tassajara Creek between the 1-580
Freeway and Gleason Drive, and the City staff shall use this plan for implementing the Stream Restoration
Program; and
WHEREAS, the Stream Restoration Program has been reviewed in accordance with the provisions of
the California Environmental Quality Act (CEQA) and the State CEQA Guidelines, and no new effects could
occur and no new mitigation measures would be required for the project that were not addressed in the Final
Environmental Impact Report (FEIR) for the Eastern Dublin General Plan Amendment and Specific Plan, and
the project is within the scope of the FEIR. The project implements mitigation measures of the FEIR and an
initial study \-vill be conducted for each development application that is required to comply with the Stream
Restoration Program document; and
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WHEREAS, the Planning Commission held a public meeting to consider this project on July 16, 1996;
WHEREAS, the Planning Commission recommended City Council approval of the Stream Restoration
Program and the Tassajara Creek Lower Reach Implementation Plan; and llFr;Ji~. r.-.,.~~.l-ir\.";~~T
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WHEREAS, the City Council held a public meeting to consider this project on August 13, 1996; and
WHEREAS, the Staff Report was submitted recommending that the City Council approve the Stream .
Restoration Program and the Tassajara Creek Lower Reach Implementation Plan.
NOW, THEREFORE, BE IT RESOLVED THAT THE Dublin City Council does hereby approve
the Stream Restoration Program and the Tassajara Creek Lower Reach Implementation Plan, as defined in
Exhibits A and C, respectively, ofthe City Council Staff Report dated August 13, 1996.
PASSED, APPROVED AND ADOPTED this 13th day of August, 1996.
AYES:
NOES:
ABSENT:
Mayor
ATTEST:
City Clerk
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TASSAJARA CREEK LOWER REACH (1-580 TO GLEASON DRIVE) IMPLEMENTATION PLAN
MAINTENANCE/OWNERSHIP/OPERATION RESPONSIBILlTI ES
.
(Keyed to attached Figures 3a and 3b of the Draft Stream Restoration Program)
ZONE 7
. Creek Corridor Ownership (includes creek channel; flood control channel/terraces on both sides of creek; 30'
minimum structure setback on both sides of creek; and maintenance roads
between 1-580 and Dublin Blvd. on both sides of creek)
. Creek Channel Operation; and Maintenance for Flood Control and Water Conservation Purposes Only, as per
the March 18, 1987 Agreement Between Zone 7 and the City of Dublin and
any Subsequent Agreement Modifications
EBRPD
. Regional Trail/Maintenance Road and 30' Structure Setback on East Side of Creek - Maintenance and
Operation (between Dublin Blvd. and Gleason Drive)
CITY OF DUBLIN (i.e.. landscape & lighting district)
. Local Trail/Maintenance Road; 30' Structure Setback; and Optional Trail Landscape Plantings Requiring
Permanent Irrigation on West Side of Creek - Maintenance (between Dublin
Blvd. and Gleason Dr. - see Fig. 3b)
..
. Optional Landscape Plantings Requiring Permanent Irrigation on East Side of Creek - Maintenance (between
Dublin Blvd. and Gleason Dr. - Fig. 3b)
Optional Landscape Plantings Requiring Permanent Irrigation on Both Sides of Creek - Maintenance (between
1-580 and Dublin Blvd. within the stream corridor)
COUNTY OF ALAMEDA
· Required Restoration Plantings - Establishment and Maintenance
(County shall establish and maintain for approx. 3 to 5 years)
· Optional Landscape Plantings that do not Require Permanent Irrigation - Establishment and Maintenance
(County shall establish and maintain for approx. 5+ years)
· Optional Landscape Plantings Requiring Permanent Irrigation - Establishment only.
AGREEMENTS NEEDED
City/County Agreement with Zone 7:
Creek Corridor Dedication
Creek Corridor Operation and Maintenance For Flood Control and Water Conservation Purposes Only
Fencing Prohibiting Vehicular Access
Acknowledgment of City's Landscape and Lighting District
City/Zone 7/County Agreement with EBRPD:
.
Regional Trail/Maintenance Road and 30' Structure Setback on East Side of Creek (between Dublin
Blvd. and Gleason Drive)
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TASSAJARA CREEK LOWER REACH IMPLEMENTATION PLAN
t_-Eeliomll l:lnc!!!!ap~anllngg tr9stor~;/:'~i!:j11Iil;lii11 --__ OP'!~?TJallaTJdsca.!!!L1!!'!.!.~~,-r;~_______-)(
'!-:md5cap" structuTfJ @ structuTfJ Landscape
.I!,as"'~~'~I~fJtback I" Flood control cll:mnel_. C ~Iood con!ro~ channel 1_ setback l/e:Jsemon_t,
1'20' mln} (30' mln11 (0100) (0100) (30' mini , (20' mln)!
@ @ Exisfin. @ @
i (EXCavate for flood
Existing g~Td. lop of b.nk.. -conl,o' cb.nno' _
~,:7/;7/7: 1 \\-- -7 'i////L//:: ' -li.!!I:-
( v,'0<,y ~$ffin-----I~;!#~~'iUF I )
MaintfJnancfJ road //@//~.::. //;;;/,,</../;/ ~ p. Maintenance road'
///: " :3:1 h'
c;;::....ndering
low flow
channel
Wildlife setback"
1---'----- -iioo' mlii;j >(- Sf'.'m CO,,'dO:
l' - ..-------- ---.-.---,---..........,
width varies
Wildfife setback"
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TYPICAL CROSS SECTION
LOWER REACH
SUBREACH 1 .. 1580 TO DUBLIN
'Mea$lIred from exi$ling ler of b,1M
NTS
ThssajaTCl Creek
Fig.3a Ownership Flood Control Maintenance Establishment Maintenance Establishment Ultimate
Maintenance & Operation of Required of Required of Optional Maintenance
Restoration Restorationl Landscape of Optional
Plantings Optional Plantings Landscape
Landscape Plantings
Plantings (:J:
3 - 5 years)
A Zone 7 Zone 7 Zone 7 N/A N/A County City - LLD
B Zone 7 Zone 7 Zone 7 N/A County County N/A
. C Zone 7 Zone 7 Zone 7 ~ unty County N/A N/A
0 Zone 7 Zone 7 Zone 7 County County N/A
E Zone 7 Zone 7 Zone 7 N/A COllnty C:ity - Lto
-- ,-.- .------..---.---- ,-- - - -----~._-- ---,.-. - - --..."
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T ASSAJARA CREEK LOWER tACH IMPLEMENTATION PLAN
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Optional landscape plantings -r~ReqUir~~--l
restoralfon planting
structure @
setback C
(30' minJ I Flood plain terrace .
Trail /roa
right-ot-wa
Optional landscape Planting~r-
structure
setback
Flood plain terrace I (30' n~!~ _
Trail/roa
right-ot-way
@)
@
@
C0
Excavate tor i Top ot bank ~
flood plain terrace .
as reqUired~ Excavate for flood. plam
. 15 year Ie ve') \_ terrace as requlred____,
'-;;~7/77 77 /%/ =177!J~~'>. ./;, - - - - -:II-~/ ~. //'7 /7:r/7 /7 j;( ~ .}
Exisflng grade.-/ = _',ul::- \ R~glOnal trall/~
-II maintenance road
Local trail/ see fIg. 9
maintenance road
see fig. 10 Exisflng grade
-f
-}-
Wildlife so tback.
-----(100' min~)
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-{-------'!il1:~~J.:~.r".--n - r
Stre.;J_Tl!~C?rr~dor _________;.('_
width varies
.Measllred from existing top of banA
TYPICAL CROSS SECTION
LOWER REACH
SUBREACH 2 . DUBLIN TO GLEASON
NTS
Tassajara Creek,
Fig,3b Ownership Flood Control Maintenance Establishment Maintenance Establishment Ultimate
Maintenance & Operation of Required of Required of Optional Maintenance
Restoration Restorationl Landscape of Optional
Plantings Optional Plantings Landscape
Landscape Plantings
Plantings (:I:
3 - 5 years)
A Zone 7 Zone 7 City - LLD N/A N/A County City - LLD
B Zone 7 Zone 7 Zone 7 N/A County County N/A
C Zone 7 Zone 7 Zone 7 County County N/A N/A
0 Zone 7 Zone 7 Zone 7 N/A County County N/A
E Zone 7 Zone 7 EBRPD N/A N/A EBRPD EBRPD
Related Eastern Dublin Specific Plan
Action Program 6F and EIR
Mitigation Measure 3.7/12
MM 3.7/12.0 (Program 6F). The City should work with Zone 7 and the Department of
Fish and Game to develop a comprehensive stream corridor restoration
program that identifies a detailed set of criteria for grading, stabilization
and revegetation of planning area stream channels. This program shall be
developed soon after approval of the General Plan Amendment and
Specific Plan. The program would provide guidelines for plant species,
planting densities, and long-term maintenance requirements and
responsibilities. Such a program will facilitate development approvals and
insure a consistent standard for stream channel improvement throughout
the planning area. The program should identify the procedures to be
followed by applicants for development, permits to be obtained, and
improvement and revegetation practices to be implemented.
Program 6F: The City should work with Zone 7 and the Department ofFish and Game
to develop a comprehensive stream corridor restoration program that
identifies a detailed set of criteria for grading, stabilization and
revegetation of planning area stream channels. The program would
provide guidelines for plant species, planting densities, and long-term
maintenance requirements and responsibilities. Such a program will
facilitate development approvals and insure a consistent standard for
stream channel improvement throughout the planning area. The program
should identify the procedures to be followed by applicants for
development, permits to be obtained, and improvement and revegetation
practices to be implemented. The program should be reviewed by East
Bay Regional Parks District.
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Eastern Dublin Comprehensive Stream Restoration Program
SUMMARY
Major Regional Resource
The watercourses found throughout the Eastern Dublin area are linked into a
comprehensive linear corridor system. This system includes one major creek, Tassajara Creek,
its tributaries, and a number of intermittent streams that drain in a southwesterly direction. The
Specific Plan designates these water courses as linear open space corridors that link community
activity centers, residential areas, and open space. These stream corridors are planned to have
pedestrian and bicycle trails that will accommodate the movement of pedestrians, bicyclists, and
equestrians throughout the planning area with minimal conflict from vehicular traffic. Where
feasible, these trails will connect into adjoining regional trails systems (i.e. East Bay Regional
Park District's and Livermore Area Recreation and Park District's trail systems.)
Tassajara Creek functions as a major regional resource for wildlife and water flow
movement. Tassajara Creek provides uninterrupted connections to other significant open space
areas in eastern Dublin (i.e. Camp Parks) and Contra Costa County (i.e. Hidden Valley, Mt.
Diablo, Morgan Territory, Black Diamond Mines and Contra Loma Regional Parks.) Tassajara
Creek also serves as a means for transporting stream runoff and groundwater seepage through
and away from the planning area. Tassajara Creek must be able to contain and transport
(convey) flood flows up to and including the 100-year design flood.
Channel Stabilitv and Erosivitv. Setbacks
The consultants discovered that Tassajara Creek is very unstable. Preliminary analysis
shows that it is a channel in transition with reaches shifting their channel patterns and habit.
Detailed professional hydrologic and possibly geotechnical studies based on the Stream
Restoration Program need to be completed prior to establishing development setbacks or altering
the channel form. These studies will confIrm existing conditions and will identify requirements
to grade the flood plain terrace to accommodate flood flows. Channel and bank stability
improvements should be designed to reduce or eliminate the potential channel transitions.
The City's minimum setback along open watercourses, which may be increased at the
discretion ofthe Public Works Director, is described in Ordinance 52-87. Figure 1 of the Stream
Restoration Program shows a hypothetical example of channel setbacks necessary to account for
the future channel transitions, which complies with the City's ordinance.
Water Quality of Runoff and Groundwater
All future Eastern Dublin development projects must comply with the City's erosion
control and water quality regulations. The quality of groundwater and urban runoff into
Tassajara Creek and its tributaries should meet the Best Management Practices, or BMPs and
other practices as identified in Section 9.3.2 of the Eastern Dublin Specific Plan. BMPs are
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measures that would prevent polluted water runoff from developed areas from entering the
natural waterway systems.
.
The draft Grazing Management Plan includes guidelines that would reduce water quality
impacts associated with cattle grazing, i.e. cattle should be grazed and watered at alternate
sources outside the stream channel. The Stream Restoration Program concludes that
enhancement, restoration and landscaping between future developments and the creek should
stabilize surface sediments.
Reclaimed Water
Reclaimed water can be used for landscape irrigation or establishing riparian vegetation
within the creek study area. The Stream Restoration Program recommends that the use of
reclaimed water to irrigate restoration plantings or trail landscaping should not impair water
quality standards. Zone 7 is currently conducting a major regional reclaimed water study. This
study will assess the potential impacts of wastewater application on ground and water surfaces.
In the interim, Zone 7 recommends that irrigation systems should be designed to be easily
switched to reclaimed water systems when such systems become an accepted policy.
Flood Control
If existing conveyance (the ability to carry flood flows) is inadequate, flood control .
alternatives, such as broadening, deepening, and smoothing the channel, and constructing levees
and bypasses should be considered.
Channel Modifications and Stabilization/Bioengineering Techniques
Channel modifications or improvements should accommodate projected flood flows and
extensive revegetation that avoids the need for periodic vegetation removal. The Stream
Restoration Program states that the flood plain terrace should be managed to support non-
irrigated grasses and where channel modifications are required, the channel should be shaped and
graded to contours with a natural appearance. A flood plain terrace is necessary to accommodate
additional flood flows. The Stream Restoration Program emphasizes that preserving the creek is
paramount to preserving the existing vegetation and wildlife corridor, consistent with the
Specific Plan's restoration goals. Most importantly, the channel should be allowed to naturally
revegetate, erode and meander within the flood plain terrace.
The document recommends that non-structural, or bioengineering solutions should be
used to increase channel capacity and stabilize stream banks while providing habitat value, and
provides examples of such solutions, e.g. vegetation or boulders. Bioengineering is a low-tech
method of construction using living plants in combination with non-living, or inorganic materials
(i.e. hard structures.)
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Resource Protection. Restoration and Mitigation
Erosion and hydrologic considerations may allow for flexibility in the biological setbacks
for Tassajara Creek and its tributaries. As long as the hydrological setback is met, the biological
or wildlife setback may be arranged to incorporate more valuable habitat on one side of the
tributary at the expense of less valuable habitat on the other side. Under no circumstances should
the wildlife setback be less than 50 feet on one side.
The Stream Restoration Program's revegetation guidelines shall apply where creek
channel grading modifications create large bare soil areas or remove large stands of vegetation.
'Where major grading and modifications are proposed to accommodate flood control and access
along Tassajara Creek between Gleason Road and 1-580 Freeway, restoration plantings shall be
required to provide stabilization and wildlife habitat, subject to the California Department ofFish
and Game review and approval.
In reaches of Tassajara Creek where existing and native vegetation is abundant and
diverse, needing no modification, little to no planting is anticipated. However, in this situation,
the City will require some native vegetation enhancement, consistent with the Specific Plan
Policy 6-11 that requires all stream corridors to be revegetated with native plant species to
enhance their natural appearance and improve habitat values.
Chapter 6 of the Stream Restoration Program includes resource protection, restoration
and mitigation guidelines for plants and wildlife. This is a very comprehensive chapter outlining
methods and guidelines for plant and wildlife habitat enhancement and restoration that project
applicants can utilize while preparing a creek restoration plan.
Studv Area - 3 Reaches
For planning and implementation purposes, the Tassajara Creek study area was divided
into 3 reaches: lower reach (1-580 Fwy. to Gleason Rd.); middle reach (Gleason Rd. up to and
including the EBRPD staging area); and upper reach (EBRPD staging area to the Contra Costa
County line.) Figure 2 of the Stream Restoration Program depicts these reaches.
Channel Cross Sections
Conceptual Cross Section for Lower Reach - Subreach 1 (Fig. 3a of Stream Restoration
Program):
1) creek channel (below Q 15) -meandering low flow channel; trapezoidal channel
2) restoration plantings below Q15
3) flood plain terrace (existing or graded terrace outside the creek, within Q100)
4) structure setback from existing top of bank - (above QI00)
5) optional landscape plantings within and outside the Q 100 that will be maintained by the City
of Dublin
3
Conceptual Cross Section for Lower Reach - Subreach 2 (Fig. 3b of the Stream
Restoration Program):
.
I) existing creek channel (below Q 15)
2) restoration plantings below the Q 15
3) flood plain terrace (within Q100)
4) structure setback from existing top of bank (above Q100)
5) optional landscape plantings within and outside the Q 100
Conceptual Cross Section for Middle Reach (Fig. 4 of the Stream Restoration Program):
1) existing creek channel (some sections contain Q100, other sections do not) - supports
vegetation
2) flood plain terrace (area above existing creek channel, or the area graded to accommodate the
flood flows below the Q 1 00)
3) structure setback (above the QIOO)
Conceptual Cross Section for Upper Reach (Fig. 5 of the Stream Restoration Program):
1) existing creek channel (readily contains 100 year flood flows) - supports riparian vegetation at
lower elevations
2) hydrological-wildlife structural setback outside the existing creek channel .
Stream Setbacks
Creek and tributary setbacks are as follows: 1) structure setback must be above the 100
year flood flows, or Q 1 00 (this is at an elevation where the worst rain will flood the area 1 time
within 100 years); 2) Tassajara Creek and major creek tributary - 100 foot minimum wildlife
setback from top of existing bank channel; and 3) minor creek tributary - 50 foot minimum
wildlife setback (trails sited within the setback should be sited furthest away from the creek.).
The combined width of the flood plain terrace and the structure setback should be a
minimum of 100 feet along both sides of the incised or graded channel to comply with the
California Department ofFish and Game requirements, unless an exception is negotiated with the
Department biologists.
For the lower and middle reaches, there should be a 30 foot minimum structure setback
(or setback from development) from outside the flood plain terrace. Wider setback should be
encouraged. Trail and maintenance access right-of-way should be located within this 30 foot
setback area to maximize public safety, enhance access for police patrols, minimize wildlife
disturbance and minimize trail maintenance resulting from erosion or siltation. The Stream
Restoration Program encourages the landscaping and vegetation of adjacent development for
creating soft edges and enhancing/enlarging the trail open space and maintenance corridor, and .
eliminating sidewalks in favor of the pedestrian and bicycle use of the regional trail.
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The wildlife and hydrological setbacks for the upper reach overlap. The greater of the
two controls the final outside edge of the stream corridor. The hydrological setbacks
incorporates structural and slope bank failure considerations for the character of this channel
portion. The wildlife setback is still 100 feet from the top of the existing bank channel.
The recommended minimum setbacks may be altered where prevailing conditions
warrant a different approach. A key circumstance would be the upper reach where the channel is
50 feet deep and the banks are nearly vertical. The Stream Restoration Program recommends a
setback of 120 feet from the top of bank to accommodate the transitional, unstable nature of the
channel. The Stream Restoration Program states that due to the serious liability related to
potentially inadequate setbacks along Tassajara Creek, the City should retain their own
hydrology consultant to evaluate any hydrologic studies.
Trails and Maintenance
The Stream Restoration Program includes a trail and maintenance roadway system that
provides multi-purpose open space corridors capable of accommodating both wildlife movement,
pedestrian, bicyclist and equestrian circulation, consistent with the Specific Plan policies. The
open space stream corridors integrate natural open space areas, developed parks and recreation
areas. The trail and open space network links regional and local trails, employment centers,
residential areas, schools, neighborhood parks, and open space.
The trail and maintenance roads should be combined to provide safe pedestrian and 2-
way bicycle use and adequate maintenance areas. In the upper reaches where the banks are steep,
creek access should be discouraged for safety reasons. The trail should be located outside the
established setback, the fencing strategically placed, and proper signage installed.
Zone 7 will require maintenance access, or gravel roads on both sides of the creek where
there is no regional or local trai1. Zone 7 requires 15 foot wide all-weather surface roads with a 6
inch compacted aggregate base, both preferably located above the Q100. If this is not practical,
Zone 7 may accept one lower maintenance road above the Q15, paved in asphalt concrete, or
concrete.
Figures 6 through 8 show a conceptual plan view of the trail and maintenance roads.
Figures 9 through 11 show trail standards for the regional trail, local trail and the maintenance
roads.
Creek Tributaries - Trails
The creek tributaries should be improved with local trails designed to connect to the
regional trail and provide convenient pedestrian and bicycle connections between neighborhoods
and other destinations within the plan area. Also, the Stream Restoration Program states that
local trails should utilize the tributary as an open space corridor connection.
5
Regional TraillMaintenance Road
.
The regional trail/maintenance road shall be provided along one side of the creek,
consistent with EBRPD and Zone 7 requirements. The regional trail shall be designed in
compliance with the City's Parks and Recreation Master Plan. The combined regional trail and
maintenance road shall include a 12 foot wide paved pathway and rocked shoulders (4' wide on
one side, and 2' wide on the other.) This regional trail should accommodate pedestrians,
bicyclists and equestrians. This trail will also adequately serve Zone Ts all-weather surface
requirement for maintenance access.
Local TraillMaintenance Road
Although the Specific Plan requires only one north-south trail along Tassajara Creek, the
Stream Restoration Program also provides guidelines and standards for a local trail system and a
combined local trail and maintenance road system. This local trail/maintenance road system
would provide connections between residential neighborhoods and destinations, such as the
regional trail, schools, parks, employment centers, open space, etc.
The document also includes standards for trail/park staging areas and trail heads for
hiking and equestrian trails, stream crossings and the development-corridor interface.
Access to both regional and local trails should be controlled through use of bollards, .
gates, fences or similar systems acceptable to the emergency response agencies. These methods
of controlling access would prohibit undesired vehicle access, while allowing for maintenance
and emergency vehicle access and encouraging bicycle use of the local trails.
Development-Corridor Interface
Development abutting the stream corridor should meet certain criteria, such as preserving
and enhancing the creek's biological values, convenient corridor access, enhancement ofthe
visibility and character of the stream corridor, etc. Figure 12 of the Stream Restoration Program
shows three types of road systems that should be incorporated into the project design for
providing an appropriate development-stream corridor interface: single loaded streets, loop
streets and cul-de-sacs.
Development that backs directly into the stream corridor should be avoided. In addition,
residential development should be oriented towards the creek as a visual amenity and schools and
parks should be designed to take advantage of creekside settings and educational opportunities.
Figure 13 depicts recommended commercial development setbacks along creeks that
would promote a smoother transition to the open space area. Screening of parking lots, storage
areas, loading docks, trash receptacles, etc. should be accomplished through landscaping. Figure
14 depicts recommended pedestrian trail access development configurations.
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Implementation and Management
In compliance with the Specific Plan, prior to any final map approvals for projects
adjacent to the Tassajara Creek or its tributaries, the City shall establish a mechanism (e.g.
landscape and lighting district) for the ownership, management and long-term maintenance of the
stream open space corridor. These improvements would include stream corridor restoration,
flood control improvements and trail construction. The City should establish this mechanism to
cover the long-term costs of maintaining public facilities (i.e., trails, roads, benches, vegetation
management, etc.) along the stream corridors. The other ownership and maintenance funding
sources include: home owners association, other public agencies (i.e., EBRPD, Zone 7, etc.),
special assessment districts, bond and tax measures, etc.
It is expected that these corridor improvements will take place in a number of phases
based on ownership patterns and timing of application submittals. The preferred phasing would
be improving the entire lower reach first, middle reach second, and upper reach third.
Funding Mechanisms
Zone 7 and EBRPD may have some funding earmarked for flood control and trail
improvements. The City's Parks and Recreation Master Plan describes other funding sources for
open space acquisition, capital improvements and operations.
Long-term maintenance and management should be accomplished through the
development of cooperative agreements between the City, Zone 7 and the EBRPD that would set
common management goals and activities and joint financing provisions. The maintenance
agencies should develop and enforce long-term maintenance and management guidelines and
standards that promote the Specific Plan stream restoration and preservation policies and the
Stream Restoration Program guidelines and development standards.
g: \eastdu b l\streams \staffrpt
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IAcKAY & SO.PS
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CIVIL ENGINEERING LAND PLANNING LAND SURVEYING
July 15, 1996
Carol Cirelli, Senior Planner
City of Dublin
100 Civic Plaza
Dublin, CA 94568
Subject: Eastern Dublin Comprehensive Stream Restoration Program
Dear Carol:
On behalf of our client, Jennifer Lin, we have reviewed the final draft of the City's proposed
Stream Restoration Program prepared in cooperation with Sycamore Associates.
We met with Marylee Guinon of Sycamore Associates and you on July 5, 1996, to discuss
comments and questions expressed in our previous response letter of April 23, 1996 (copy
attached). A number of concerns were resolved in our meeting, however, there are still many .
specific requirements and guidelines contained in the current document that we see as
problematic and generally unworkable, particularly with respect to implementation of a land plan
for Dublin Ranch in accordance with the Eastern Dublin Specific Plan.
Our primary concerns with the proposed program still revolve around references to a 100'
minimum CDF & G "standard" for creek setbacks as a legal requirement; procedures by which
creek set backs are measured; lack of flexibility for implementing !he guidelines and allowance
for guideline modifications; and cost/phasing/fmancingljurisdictional maintenance issues that are
not clearly addressed in the document.
One of our most notable concerns involves the document's repeated reference to the 100 foot
setback as a CDF & G "standard". At numerous locations in the text and exhibits it seems to
be implied that the 100 foot setback is a legal requirement, however, this setback is only a
recommendation that CDP & G can make during the environmental review and permitting
processes. The document should be reworded to state that CDP & G "typically recommends a
100 foot setback...". The need to revise this inaccurate wording is further substantiated by the
text wording within the Eastern Dublin Specific Plan under Program 6G.
The recommendation on page 59 that setbacks from major tributaries "should never be less than
100 feet" or a "minimum of 100'" is too rigid and precludes the opportunity for negotiating a
lesser setback with the regulating agency. In addition, this language does not account for site
specific conditions where a flat 100' setback is not warranted such as areas that are degraded,
have little or no vegetation, have artificial materials or surfaces (rip rap, gunite, etc.) on the bed or
banks, etc. Flexibility and allowances should be made equally for actual physical conditions in
both Tassajara Creek and its tributary channels. Site conditions which would warrant such
flexibility in offsetting or reducing the recommended setbacks include creek or tributary sections
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5142 FRANKLIN DRIVE, SUITE B PLEASANTON, CALIFORNIA 94588-3355 PHONE (510);~.:. 25.~96.._ 9Q..1 !.~F-. A.:'.'>l .-.(.51,.Qt2.22t> -0698F
OFFICES: FAIRFIELD PLEASANTON ROSEVILLE SACRAMENTO ~SA~ i~F~ ~.f;'\ {1 ~l
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Carol Cirelli
Eastern Dublin Stream Corridor Restoration Program
Page 2
16034-0
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with lower quality of habitat, adjacent developed land uses, stable embankment conditions, I
minimal existing or expected areas of disturbance, minimal vegetative cover, etc. .J
On page 59, it is also noted that erosion and hydrologic considerations "may allow" for
flexibility in determining the biological setbacks for tributaries in terms of both distance and ;
offsetting on the different sides. The wording of this sentence should be amended to read:
"should allow". Additionally, this greater level of flexibility should also be applied to setbacks
along Tassajara Creek as well as its tributaries.
A second area of concern is the procedure by which setbacks are measured. Based on the
description on page 26 and in Figure 1, the recommendation that setbacks be measured from the
outermost limit of a stream meander is excessive in terms of the substantial land area designated
for future development in the Eastern Dublin Specific Plan which would be pre-empted. In /1
addition, the data in this Program does not conclusively document that these meanders are I
particularly dynamic and is not consistent with the field observations of our consultant team. In
light of the fact that the upper reach of the channel is deeply incised and contains what presently
appears to be stable vegetative cover as well as the minimal level of field investigation and
analysis which was permitted for this study effort, it is questionable whether the setback
distances recommended are appropriate.
.
Due to of the loss of developable land associated with this setback approach, it would be
worthwhile to consider providing stabilization measures for such creek sections which might
potentially allow for land areas between meanders to be used if an adequate setback from the top
of bank is provided. It is suggested that aerial photos taken over the last 40-50 years of
Tassajara Creek and its tributaries be thoroughly analyzed to accurately determine whether these
meanders have been actively changing over this time frame. A more detailed and site specific
analysis might also be considered to further identify where future creek meanders might occur in
order to determine if a f1~t setback distance of 100' or greater is really justified.
'5
Another area of concern is the document's apparent lack of flexibility with respect to
implementing and modifying the proposed guidelines. The City's staff report suggests that
the City "may apply some flexibility implementing these guidelines and allow some guideline
modifications, only if these changes meet the overall intent of the Specific Plan goal, policies and
action programs, and Stream Restoration Program criteria and guidelines." (p
Much of the language in the Program, however, has the effect of placing other goals in the
Eastern Dublin Specific Plan in a subservient position to the "guidelines" of other agencies. We
think this approach is backwards. The changes suggested in this letter re-enforce the flexibility
described in the staff report without sacrificing either the overall intent of the Program or the
primacy of the City's role in guiding development in Eastern Dublin. Thus, we believe that the
document should clearly state (probably in the implementation section) that the City of Dublin is
the ultimate authority in determining the appropriate application of these guidelines.
Other problematic issues involve the cost, phasing, monitoring, ownership, maintenance
. and financing of the Program. Project construction is suggested to not begin until all required 7
permits have been secured and, in the event that construction is phased, permits should be
secured for the entire project before construction begins in anyone area. We completely disagree
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Carol Cirelli
Eastern Dublin Stream Corridor Restoration Program
Page 3
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with both of these requirements. Normal practice is for some construction activities to typically
begin before all permits are secured. Additionally, the proposed requirement to secure all
permits for the entire project before construction commences is inconceivable as many years
could occur between various development phases of a large project such as Dublin Ranch. This
would be especially problematic for permits (e.g. Corps of Engineers Section 404 permits)
which stipulate that construction must be initiated within a set period of time following issuance
of the permit.
There is very little detail provided in the text with respect to costs for establishment an~
maintenance of revegetated stream corridor areas. In order for affected land owners to be able to
clearly understand the fmancial impact, a section needs to be added which addresses specific cost
items, unit prices, assumptions, etc. applicable to this Program.
On page 14 the document specifies that the City of Dublin is interested in having EBRPD and
Zone 7 assume ownership of and manage portions of the stream corridor. However, the text
also needs to identify specifically where local trails and trail easements are to occur through
proposed development areas and along tributaries, as well as who will own, manage, fund and
assume liability for them.
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We are also interested in understanding what the ramifications to Dublin Ranch would be if the
stream corridor lands within their property area dedicated to EBRPD. What would be the impac J 0
with respect to future maintenance, monitoring, and liability for such lands? Since we are no .
fully aware of the consequences of dedicating these stream corridor lands to EBRPD, we reserve
the right to discuss this issue in greater detail in the future.
The project scheduling and phasing discussion on page 17 implies that activities along th
Tassajara Creek corridor and its tributaries will be phased over time. However, no further det .
is provided as to how various items will work together, what items need to be addressed
related to the entire reach of the creek, how costs of improvements would be paid for and share
in a benefit analysis, etc. Furthermore, on page 72, it is noted that restoration projects are to b II
phased when the project is too large or costly to execute at one time or when land ownershi
patterns and project administration necessitate the need for phasing. Phasing is expected t
coincide with construction of the flood terrace, trails, and roads in conjunction with adjacen
development. The text specifies that phasing would allow the City and landowners to estab1is
procedures for "planning, plan review, permitting, construction, maintenance and monitoring"
Exactly how these tasks will be coordinated and whether all landowners must buy into th
procedures needs to be clearly addressed in the Program.
Page 123 mentions that creek improvements will occur by reaches. It should be noted that th
preferred phasing approach to move sequentially upstream with improvements may not coincid
with timing of actual development priorities and infrastructure improvements. If thes J A
improvements are to occur by reach, at what point in the development process would they b
constructed? How funding and reimbursement for improvements would be addressed als
needs to be clarified as part of this discussion.
A Habitat Monitoring Program and a Horticulture Monitoring Program are recommended to bi 15 .
established on pages 116-120. Please clarify how implementation of these programs will b
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Eastern Dublin Stream Corridor Restoration Program
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determined and funded. In addition, consideration should be given to merging these two
programs since they're not significantly different. Whether the programs will be implemented
by individual landowners or on a creek- wide basis also needs to be addressed. Additionally, we
have some concerns about specific goals, standards and review times for the habitat and
horticulture monitoring programs especially since the Corps will need to approve any such
program if it is intended to meet mitigation requirements. If goals and standards are included
with this programs, they should be written generally, not quantitatively, to provide consistency
between the two programs. Additionally, any large area of planting, not just 100 or more trees
as is specified in the text, should qualify as a representative sample plot.
Furthermore, both of these monitoring programs should end if and when all the goals and
standards have been achieved. In this regard, all references in the text to the establishment 1<1
maintenance period and monitoring of mitigation areas under either program should state that
they will apply for a period of up to five years or until program requirements have been
achieved.
Page 69 of the document specifies that an individual should monitor the establishment of the] J ,...
mitigation p1antings for five years. Please clarify how will this position be fIlled, which agency
will be responsible for implementing this action, and how this would b~e funded.
On page 117 it is also recommended that a maintenance manual be developed prior to installation
of plant materials. Since the purpose of the manual is to provide consistency for all phases, will
this document be prepared for all phases at the commencement of the first development project?
Also, who will prepare and oversee preparation of the document and how will funding and
reimbursement work? Please provide clarification for these and any other related issues.
I~
Additional Items of Concern:
In addition to our primary concerns described above, we would also note the following
additional specific comments and questions concerning other elements of the proposed
Comprehensive Stream Restoration Program:
.
With respect to plan review, the text should be revised to state that individual project
development plans may be reviewed by EBRPD, Zone 7 and CDF & G but that those
entities shall have approval authority only if they will become the ultimate owner/manager of
the corridor within an individual land holding or, as in the case of CDF & G, an existing
natural feature occurs which is protected by their agency (e.g. with respect to stream
alteration).
t7
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It is recommended that the California Department of Fish and Game review and approve this
document in writing prior to City adoption in order to gain their clear acceptance of the
policies and procedures recommended within. This would help to reduce potential
complications later in tb.e permitting, construction monitoring and maintenance phases as
future projects are proposed for development. In particular, we are concerned that the basic
trail design proposed on both sides of the creek may not be in conformance with CDF & G
desires.
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DA VE:Corres.:1996:16034-0cg7 /1l/96StreamRestoratn
With regards to the various detailed trail recommendations included, this document is not the
appropriate vehicle to determine where local trails should occur in Eastern Dublin. Trail
locations have been identified in the Specific Plan as well as the City's Parks and Recreation
Master Plan and in some cases the recommendations in this document are not consistent
with them. In the instance of Figure 11- Local Trail, the condition shown does not appear to
exist within any of the stream or tributary corridor areas, but rather, through potential
development areas.
Trail access points and staging area amenities as specified on pages 49 - 51 are excessive,] J. J
both in quantity and type.
Carol Cirelli
Eastern Dublin Stream Corridor Restoration Program
Page 5
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· On page 50 under Section 5.2.4, it is stated that the regional trail/maintenance road should
cross the creek at the staging area. Given the density of vegetation in that area, it would be J..'.
worthwhile to explore alternative locations upstream or downstream for constructing the
crossing. The existing crossing at the staging area is fine for pedestrians but would have to
DA VE:Corres.'1996:16034-Ocg7/l1/96StreamRes'oratn
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A map needs to be included in the document identifying all major and minor tributaries Of]
Tassajara Creek referenced in the text. It is very confusing as to what constitutes a
major/minor tributary and where each type of tributary is specifically located within Eastern
Dublin.
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· The various exhibits and the text should be revised to show local and regional trails
maintenance roads restricted to only one side of a corridor. This a~tion would help to further
preserve and protect the habitat of the creek and tributaries. The Program's recommendations
are clearly in conflict with Specific Plan Policy 6-13 which identifies the "single-side"
approach for trails as a desired objective and needs to be revised accordingly. In addition,
given the fact that there will be many fewer residents in proposed development areas
surrounding the upper reach of Tassajara Creek than in more intensely developed areas to the
south, there is no reasonable justification for providing both a regional trail and local trail
within that particular area. The Specific Plan policies also do not specifically mandate that a
dual trail system be provided along the creek corridor.
· ., Figure 10 illustrates only one setback from the trail, that being on the creek side. However,]
in instances where no private buffer occurs, a minimum setback should be shown on the side
which would abut development.
.
On page 49, it is suggested that the structure setback be widened to allow for the regional trail
to meander. The justification as why additional meandering of trails beyond this setback ~ tf
limit needs to be clearly documented in the text. Rather than widening the structure setback,
we suggest that the trail should be permitted to meander throughout the 100' wildlife setback
in all reaches of the creek within reasonable safety limits.
The regional trail/maintenance road should be included within the wildlife setback area SUCh] '") r
as the local trail is shown on Figure 5. Also on Figure 5, as is typical of much of the upper iI':J
reach, the top of bank should really start at the comer of the lower bench and not at the upper
bench.
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Eastern Dublin Stream Corridor Restoration Program
Page 6
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?e reconstructed to accommodate vehicl~s and the impacts woul? be significant, Particular~yJ
m terms of tree removal. The specific sIte for such future crossmgs should not be locked III
as part of this Program.
· The text on pages 68 - 69 specifies that no mitigation credits should be applied to street or
landscape trees planted within the stream corridor as part of restoration efforts. In particular,
trees planted within the stream corridor buffer, if present, should receive mitigation credits or :z 7
park/open space credit. This text for this section should also require that tree plantings be the
same species as those removed or compatible with those tree species planted within the
adjacent stream corridor areas.
.
The recommendation under Section 3.3.5 on page.16 that all riparian trees be replaced at a
3: 1 ratio regardless of DBH is excessive, particularly in the case of thickets of numerous
small-stemmed trees such as willows. In some cases, a 3: 1 replacement for a small but
dense thicket could result in an inordinately high mitigation requirement. We recommend
that in the case of dense, small-stemmed thickets of riparian trees that the acreage of
vegetation impact be replaced on a 3: 1 basis. Given the typically rapid growth of these
species, this mitigation approach will result in full compensation for the habitat loss within a
relatively short period of time. The last sentence in the paragraph s~ould specifically exclude,
by species name, invasive non-native trees such as tree-of-heaven, black locust, eucalyptus,
etc. These invasive non-native trees should be excluded from the 3: 1 replacement
requirement.
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Under the Specimen Tree Protection item on page 5, the text mentions that anv existin,?
native vegetation should be protected. This conflicts with page 68 of the text and page 2 of
the checklist of Special Submittal Requirements for tentative subdivision maps which only
protect trees. Additionally, the policy associated with this paragraph specifies that tree
disturbance or removal should be "minimized." This sentence should be rewritten to apply
only to native trees considered healthy as described in other sections of the Stream Corridor
Restoration Program.
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The basis for the recommendation that creek crossings should be located approximately
every 2000 feet as noted on page 49 needs to be stated. Rather than dictating a certain
distance between crossings, attempts should be made to locate creek crossings where widths
between creek banks are reasonable, existing native vegetation is limited, sensitive habitat is
not impacted, and embankment conditions are relatively stable. Additionally, if crossings are
to be placed above future potential creek meander sections anticipated to be moving down the
creek, as noted on page 51, the engineering and construction costs of such a crossing would
likely be prohibitive.
30
· Page 61 notes that soil compaction during the installation of bioengineering structures is J I
discouraged, however, normal construction practices to prepare a site prior to improvements
requires soil compaction to occur. Bioengineering structures and installation techniques
should be discussed in greater detail in the text.
· The requirement for soils testing, particularly with respect to agriculture suitability, seems] ');L
extreme and costly for a project of this type.
DA VE:Corres.:1996:J6034-0cg7/lJ/96StreamRestoratn
Carol Cirelli
Eastern Dublin Stream Corridor Restoration Program
Page 7
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We believe that further clarification and reconsideration of various items in this document are
warranted before it is considered for approval by the Planning Commission and Council. In
particular, we would note again the need to revise those sections that are inconsistent with the .
Eastern Dublin Specific Plan and ElR. We would appreciate an opportunity to meet with you
and other City staff further to discuss these items in greater detail before action is taken on the
proposed Plan.
111
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The text on page 115 specifies that ground or well water should not be used as a source for
temporary irrigation uses, however, no documentation is provided as to whether ground
water quality problems actually exist. This source is already used by existing vegetation
which has access to the groundwater table. Additionally, the document on page 118 suggests
that the irrigation system be monitored and repaired monthly which seems really excessive.
The document is not clear as to whether the HEC-II modeling for Tassajara Creek and itS]
tributaries will be prepared by the City or Zone 7. This will affect when property owners
undertake their own site specific HEC-II analysis.
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We question whether a biological corridor connections map is actually necessary as identified
on page 2 of the checklist of Special Submittal Requirements for Tentative Map. This map is
basically a duplication of information already shown on various Specific Plan maps. In
addition, the requirement to provide landscaping plans adjacent to Tassajara Creek or its
tributaries as described on page 3 of checklist of Special Submittal Requirements for
Tentative Map is also questionable. Most of the information to be illustrated on this map is
already shown on other required maps.
Thank you for the opportunity to comment on the City's proposed Eastern Dublin
Comprehensive Stream Restoration Program and for your consideration for our comments and
questions. -
Sincerely,
MACKAY & SOMPS
1P4 V1;. Ob4?$~~rh-
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David W. Chadbourne
cc:
Eddie Peabody, Community Development Director
T. Fairfield
J. Tong
M. Inderbitzen
R. Andrade
R. Harris
D. Stephens, H.T. Harvey & Associates
L. Berry, NUVIS
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Staff Responses
to
MacKay & Somps' Letter Dated July 15, 1996
1.
The California Department of Fish and Game (CDF&G) does refer to the 100 foot setback from
creeks as a "standard", not a "recommendation." However, according to the CDF&G, the 100 foot
setback standard is negotiable. All references to the CDF&G's 100 foot setback standard were
revised to include wording that this standard is negotiable. The biological setback is technically
founded and comprising the setback will impact wildlife.
2.
The Stream Restoration Program includes recommended guidelines and standards for biological
and hydrological setbacks. The Program's recommended setbacks may be flexible and negotiable
depending on the results of detailed biological and hydrological studies submitted with PO rezone,
tentative map and final map applications. Also, the document was revised recommending that
minor creek tributaries with trails should have a minimum 50 foot setback, instead of the previous 75
foot setback.
3.
The sentence is worded adequately. The City may apply flexibility with creek setbacks after
reviewing applicant's required erosion and hydrologic studies and potential solutions for flood
control.
4.
This is a recommended procedure for measuring setbacks in the upper reach of Tassajara Creek
due to the consultant's concern for public safety and creek stability. The applicants can propose
engineering alternatives for creek stabilization that may reduce the need for larger setbacks. The
comment that "...there appears to be stable vegetative cover in the deeply incised portion of the
upper reach, and so it is questionable whether the setback distances recommended are
appropriate," is not correct. There are only annual grasses and sparse young trees along the banks
of the upper reach. Since grasses rejuvenate annually, there is no stable vegetative cover. In
addition, our consultant (Sycamore Associates), has documentation that the biologist for the
Jennifer Un family, HT Harvey Associates, also recommended a 100 foot setback from the top of
bank in the upper reach.
The applicants will need to provide us with this information when they apply for tentative map
approval. Although interesting, 40 to 50 years is not a significant hydrologic time frame and could
not provide conclusive evidence.
The "Introduction" section of the Stream Restoration Program was revised to include a statement
that the document includes recommended guidelines and standards. The City Council resolution
includes a finding that the City of Dublin is the ultimate authority in determining and implementing
appropriate guidelines for stream restoration. The document's language does not place the goals of
the Eastern Dublin Specific Plan in a subservient position to the guidelines of other agencies.
According to the Specific Plan and the Eastern Dublin Specific Plan EIR, all projects adjacent to the
creek, or projects that may impact wetland areas, require the consultation of CDF&G and the U.S.
Army Corps of Engineers, and may require permits/agreements from these agencies.
It is essential to have all permits secured for any development project before construction begins so
that setback options are protected for purposes of wildlife protection and flood control. The City
does not want limited setback options.
8.
The City has attained this information for the lower reach of Tassajara Creek. The City does not
have sufficient information on the costs for creek restoration and trail/maintenance road construction
for the middle and upper creek reaches at this time because proposals for work are very unclear.,
e.g. upper reach. This will be determined when land owners submit preliminary development plans.
.
9. This has already been determined for the lower reach. For the middle and upper reaches, this will
be determined when land owners submit preliminary development plans.
10. See # 9 above.
11. See #9 above.
12. The Stream Restoration Program recommends that improvements be made by reaches.
Development along the creek will dictate this possibility. For example, the Alameda County Surplus
Authority is required to complete the lower reach restoration and flood control improvements within
3 years, or by 1999. Timing, funding and reimbursement for improvements will be determined when
land owners within the middle and upper reaches submit preliminary development plans.
13. The document has been revised to clarify that the Habitat Monitoring Program and Horticulture
Monitoring Program are requirements of the regulatory agencies' permitting process. As stated on
pp. 116 and 120 of the document (first sentence under each section, 6.36 Horticultural Monitoring
and Establishment Maintenance and 6.37 Habitat Monitoring, respectively, horticultural and habitat
monitoring will be conducted as part of permit requirements established by the CDF&G, the Army .
Corps of Engineers, and the State Water Quality Control Board. The quantitative figures given in
this section of the Program are guidelines. A representative sample lot of vegetation should be 100
or more trees, not any large area of planting.
14. The paragraph on page 120 under "6.37 Habitat Monitoring" has been revised to state that the
quantitative monitoring of restoration or mitigation areas should be conducted for five years, or when
all performance standards have been met. The Horticultural Monitoring Program should commence
with site preparation and vegetation installation, continuing through the establishment period. The
document has been revised on page 119, last paragraph to state that the plant growth and mortality
should be checked a minimum of 2 times per year until the performance standards and
establishment goals have been achieved.
15. The City has not yet determined this. It is important to note that according to the Eastern Dublin
Specific Plan adopted policies, development within the Eastern Dublin area must pay its own way.
16. See #15 above.
17. See response to #6 above. The City will consult with these agencies because they are experts in
the field of creek restoration and wetland protection. These agencies do not have a formal approval
process with local e1'tities. Each of these regulatory agencies has their own approval authority.
18.
The City's consultant, Sycamore Associates, has worked closely with the CDF&G while preparing .
the document. The CDF&G has reviewed and commented on the document and concurs with the
document's creek setbacks and buffer configurations, as specified in their letter to the City dated
March 7, 1996. The City will, at their own discretion, consult with the CDF&G, if necessary, for
determining adequate and appropriate resource protection.
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.9.
.3.
24.
25.
26.
27.
28.
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The City's scope of work for the consultant did not include a detailed research, or preparation of
new maps of all major and minor tributaries within the Eastern Dublin area. Applicants will be
required to identify these tributaries when applying for rezone and tentative map approval.
20.
The primary purpose for including a local trail plan is for complying with Policy 6-3 of the Eastern
Dublin Specific Plan, which states "Provide convenient access from developed areas to designated
open space areas and trails. Emphasize pedestrian connections between developed and natural
areas." Figure 11 shows how a local trail can link users (pedestrians, bicyclists, etc.) from
residential areas, school sites, or commercial areas, to the primary regional trail. This figure shows
a local trail perpendicular to the creek, and to the regional trail. In addition, the purpose of this
graphics is to show the construction detail of the local trail.
21.
The City will determine this on a case by case basis.
22.
The document includes a statement that constructing a local trail is an option for the City, and that
the Eastern Dublin Specific Plan only requires one trail (a regional trail) along one side of Tassajara
Creek. Also, Program 68 of the Specific Plan states that the City should require dedication of land
and improvements (Le., trails, revegetation, etc.) along both sides of the stream corridors as a
condition of subdivision approval. The advantage of having a local trail is that it can connect
residential and commercial land uses, including schools, community centers, etc., within the Eastern
Dublin area, and provide convenient access for pedestrians, bicyclists and equestrians.
Figures 3a, 3b, 4 and 5 of the Program show structure (development) setbacks.
The trails can be located within the flood plain terrace (see Figure 4) while keeping the 100 foot
wildlife setback unchanged. The document was revised to clarify that both the regional and local
trails within the upper reach may occur within the wildlife setback (see p. 50, paragraph under
"Upper Reach of Tassajara Creek").
If the upper reach is left in its natural state (in terms of flood control purposes), the East Bay
Regional Parks District prefers that the regional trail be placed towards the outside of, but within the
wildlife setback area for public safety and liability reasons. The lower bench of the creek is not a
creek bank.
The Program recommends a regional trail crossing at the staging area. The final location has not
yet been determined.
Restoration efforts will not be valuable to wildlife within, or adjacent to developed areas. For this
reason, the Program does not recommend giving mitigation credits for street or landscape trees
planted within the structure setback. The only restoration that will count towards mitigation credits is
the restoration that occurs within the streambed, which will be self-sustaining over the long term.
The City's biologist, Sycamore Associates, does not recommend changing the riparian tree
replacement standards. The professional standard is to not count multiple stems of a single tree as
numerous trees. It is most likely that applicants would not favor counting multiple stems of a single
tree for replacement mitigation anyway because it would be costlier. For purposes of maintaining
appropriate levels of riparian habitat values, each small-stemmed riparian tree should be counted
individually for a 3:1 replacement. The last sentence of the paragraph under "3.3.5 Specimen
Trees" stating "...non-native trees should be replaced with native trees at the 3:1 ratio since native
birds are known to nest in these exotic trees," has been added because native species do nest in
non-native trees. .
29. The guidelines address protection and mitigation of non-tree like vegetation and in places focuses
on tree protection and mitigation.
30. The wording "(spaced 2,000 feet apart)" has been deleted from the bottom paragraph on p. 48,
continuing to p. 49.
31. The City will analyze this on a case by case basis.
32. The City and Sycamore Associates do not agree with this statement. Soils testing is not costly and
is an inexpensive investment in identifying plant/soil incompatibility problems, especially in these
unique soil conditions.
33. Zone 7 flood control engineer, David Lund, informed Sycamore Associates that there is a ground
water quality problem. The statement that the irrigation system should be monitored and repaired
monthly, is a recommendation.
34. The applicants will be required to do the HEC-II modeling for Tassajara Creek.
35. The Eastern Dublin Specific Plan maps do not contain sufficient detailed information on the
biological connections along Tassajara Creek and its tributaries because minor changes in
development could affect wildlife migration. The Specific Plan maps could be used as a base map .
to show locations where biological corridors are protected (e.g. culverts) or blocked. Regarding the
"Landscaping Plan Adjacent to Tassajara Creek" requirement, the City would not want a duplication
of efforts if the items listed under this submittal requirement are already shown on other application
submittal maps. .
g:\eastdubl\stream\macrespo
.
115
--rt>TfIl l'if; ~3eS