Post on 14-Mar-2020
F I N A L R E P O R T
V O L U M E 2 : A P P E N D I C E S
DYNAMIC STABILITY ANALYSIS
OF ESTATES DAM
OAKLAND, CALIFORNIA
Prepared for
East Bay Municipal Utility District
375 Eleventh Street
Oakland, California 94607
November, 2006
URS Corporation 1333 Broadway, Suite 800 Oakland, California 94612
26814957.E0000
TABLE OF CONTENTS
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VOLUME 1
Executive Summary............................................................................................................................... ES-1
Section 1 ONE Introduction..................................................................................................................... 1-1
1.1 Background.............................................................................................. 1-1
1.2 Purpose and Objectives............................................................................ 1-1
1.3 Previous Investigations ............................................................................ 1-1
1.4 Report Organization................................................................................. 1-1
Section 2 TWO Scope of Work ................................................................................................................ 2-1
Section 3 THREE Project Description......................................................................................................... 3-1
3.1 Site Setting ............................................................................................... 3-1
3.2 Description of Dam.................................................................................. 3-1
3.3 Appurtenant Facilities.............................................................................. 3-1
3.4 Construction History................................................................................ 3-1
3.5 Performance and Monitoring ................................................................... 3-2
Section 4 FOUR Field and Laboratory Investigations ............................................................................. 4-1
4.1 Field Investigations.................................................................................. 4-1
4.1.1 Rotary Wash Drilling................................................................... 4-1
4.1.2 Hammer Energy Measurements................................................... 4-2
4.1.3 Downhole Geophysical Surveys .................................................. 4-2
4.2 Laboratory Testing................................................................................... 4-2
Section 5 FIVE Geological Setting .......................................................................................................... 5-1
5.1 Regional Geology .................................................................................... 5-1
5.2 Site Geology............................................................................................. 5-1
5.3 Fault Rupture ........................................................................................... 5-2
Section 6 SIX Site - Specific Earthquake Ground Motions ................................................................. 6-1
6.1 General Approach .................................................................................... 6-1
6.2 Seismic Sources ....................................................................................... 6-1
6.3 Design Response Spectra......................................................................... 6-2
6.3.1 Site Conditions............................................................................. 6-2
6.3.2 Attenuation Relationships............................................................ 6-2
6.3.3 Deterministic Ground Motion Analysis....................................... 6-2
6.3.4 Fault Rupture Directivity Effects................................................. 6-3
6.3.5 Design Response Spectra............................................................. 6-3
6.4 Spectrum-Compatible Acceleration Time Histories................................ 6-4
TABLE OF CONTENTS
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Section 7 SEVEN Embankment and Foundation Conditions.................................................................... 7-1
7.1 Dam Materials and Zonation ................................................................... 7-1
7.2 Embankment Conditions.......................................................................... 7-2
7.2.1 1903 Fill ....................................................................................... 7-2
7.2.2 1938-39 Fill.................................................................................. 7-3
7.3 Foundation Conditions............................................................................. 7-5
7.3.1 Foundation Soils .......................................................................... 7-5
7.3.2 Bedrock ........................................................................................ 7-6
7.4 Groundwater Conditions.......................................................................... 7-6
Section 8 EIGHT General Analysis Approach........................................................................................... 8-1
Section 9 NINE Limit Equilibrium Stability Analyses............................................................................. 9-1
9.1 Analytical Procedures .............................................................................. 9-1
9.2 Cross Sections.......................................................................................... 9-1
9.3 Material Properties................................................................................... 9-1
9.4 Analysis Results....................................................................................... 9-1
Section 10 TEN Dynamic Response Analyses...................................................................................... 10-1
10.1 Methodology.......................................................................................... 10-1
10.2 Dynamic Material Properties ................................................................. 10-1
10.2.1 Shear Wave Velocities............................................................... 10-2
10.2.2 Modulus Reduction and Damping Relationships ...................... 10-2
10.3 Analysis Results..................................................................................... 10-2
10.3.1 1989 Loma Prieta Earthquake.................................................... 10-3
10.3.2 Hayward-Rogers Creek Fault Mce ............................................ 10-3
10.3.3 San Andreas Fault Mce.............................................................. 10-4
Section 11 ELEVEN Seismic Stability Analyses .......................................................................................... 11-1
11.1 Approach................................................................................................ 11-1
11.2 Evaluation of Potential Strength Loss in Embankment and
Foundation Soils .................................................................................... 11-1
11.2.1 Evaluation Procedures ............................................................... 11-1
11.2.2 Potential for Strength Loss......................................................... 11-3
11.3 Post-Earthquake Slope Stability ............................................................ 11-3
11.4 Deformation Analyses ........................................................................... 11-3
11.4.1 Methodology.............................................................................. 11-3
11.4.2 Yield Acceleration Evaluation................................................... 11-3
11.4.3 Analysis Results......................................................................... 11-4
11.5 Sensitivity of Calculated Deformations to Ground Motion Time
Histories ................................................................................................. 11-5
11.5.1 Additional Ground Motion Time Histories................................ 11-5
11.5.2 Simplified Newmark Analysis................................................... 11-5
TABLE OF CONTENTS
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Section 12 TWELVE Nonlinear Analyses ...................................................................................................... 12-1
12.1 Methodology.......................................................................................... 12-1
12.2 Material Properties................................................................................. 12-1
12.3 Analysis Results..................................................................................... 12-2
12.3.1 1989 Loma Prieta Earthquake.................................................... 12-2
12.3.2 Hayward-Rogers Creek Fault Mce ............................................ 12-2
12.3.3 San Andreas Fault Mce.............................................................. 12-3
Section 13 THIRTEEN Three Dimensional Stability Effects............................................................................ 13-1
13.1 Approach................................................................................................ 13-1
13.2 Three Dimensional Slope Stability Analysis ......................................... 13-1
13.3 Dynamic Response Analysis.................................................................. 13-2
13.4 Deformation Analysis Results ............................................................... 13-3
Section 14 FOURTEEN Expected Dam Performance ........................................................................................ 14-1
Section 15 FIFTEEN Conclusions .................................................................................................................. 15-1
Section 16 SIXTEEN References .................................................................................................................... 16-1
List of Tables, Figures and Appendices
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Tables
Table 3-1 Existing Piezometers at Estates Dam
Table 4-1 Summary of Borings
Table 6-1 Main Earthquake Sources in the Region
Table 6-2 Selected Attenuation Relationships
Table 6-3 Calculated Horizontal Peak Ground Acceleration
Table 6-4 Recommended Design Response Spectral Values
Table 6-5 Earthquake Records Used to Develop Time Histories for Hayward-Rodgers Creek
Fault and San Andreas Fault MCEs
Table 7-1 Representative Index Properties of Embankment and Foundation Materials(1)
Table 7-2 Strength Parameters for Embankment and Foundation Soils
Table 7-3 Comparison of Effective Stress Strength Parameters Between This and Previous
Studies
Table 7-4 Comparison of Total Stress Strength Parameters Between This and Previous
Studies
Table 9-1 UTEXAS3 Input Parameters for Static Stability Analysis - Long Term Condition
Table 9-2 UTEXAS3 Input Parameters for Seismic Stability Analysis - Pre-Earthquake
Condition
Table 10-1 Material Parameters for Dynamic Response Analysis
Table 11-1 UTEXAS3 Input Parameters for Seismic Stability Analysis – Post-Earthquake
Condition
Table 11-2 Yield Acceleration Coefficients of Selected Sliding Blocks
Table 11-3 Calculated Horizontal Displacement in Newmark-type Analyses
Table 11-4 Calculated Horizontal Displacements in Newmark-type and Simplified Newmark
Analyses
Table 12-1 Material Properties for Static Stress Analysis
Table 12-2 Material Properties for Dynamic Analysis
Table 12-3 Calculated Downstream Slope Horizontal Displacements (in feet)
Table 12-4 Calculated Crest Vertical Displacements (in feet)
Table 13-1 Calculated Factors of Safety and Yield Acceleration Coefficients
Table 13-2 Calculated Downstream Horizontal Displacements (in feet)
List of Tables, Figures and Appendices
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Figures
Figure 1-1 Site Location Map
Figure 3-1 Location of Estates Dam and Reservoir
Figure 3-2 Site Plan
Figure 4-1 Locations of Previous Field Explorations
Figure 4-2 Locations of Field Explorations
Figure 5-1 Geological Map of the Estates Reservoir Area
Figure 6-1 Map of Regional Seismic Sources
Figure 6-2 Calculated 84th-percentile Acceleration Response Spectra for Hayward-Rodgers
Creek Fault MCE
Figure 6-3 Calculated 84th-percentile Acceleration Response Spectra for San Andreas Fault
MCE
Figure 6-4 Design Acceleration Response Spectra for Hayward-Rodgers Creek Fault MCE
Figure 6-5 Design Acceleration Response Spectra for San Andreas Fault MCE
Figure 6-6 Recorded Time History, 1992 Landers, CA, Earthquake at Lucerne Valley
Station, Horizontal Component, 270 deg.
Figure 6-7 Acceleration Response Spectra, 1992 Landers, CA, Earthquake at Lucerne Valley
Station, Horizontal Component 270 deg.
Figure 6-8 Recorded Time History, 1995 Kobe, Japan Earthquake at KJMA Station,
Horizontal Component, 142 deg. (Rotated)
Figure 6-9 Acceleration Response Spectra, 1995 Kobe, Japan Earthquake at KJMA Station,
Horizontal Component, 142 deg.
Figure 6-10 Recorded Time History, 2002 Denali, Alaska, Earthquake at Carlo, Alaska
Station, Horizontal Component, 360 deg.
Figure 6-11 Acceleration Response Spectra, 2002 Denali, Alaska, Earthquake at Carlo, Alaska
Station, Horizontal Component 360 deg.
Figure 6-12 Hayward-Rodgers Creek Fault Event, Recommended Time History # 1
Figure 6-13 Hayward-Rodgers Creek Fault Event, Recommended Time History # 2
Figure 6-14 Comparison of Acceleration Response Spectra for Hayward-Rodgers Creek Fault
Event
Figure 6-15 San Andreas Fault Event, Recommended Time History
Figure 6-16 Comparison of Acceleration Response Spectra for San Andreas Fault Event
Figure 7-1 Locations of Field Explorations
Figure 7-2 GIS Model – Isometric View of Dam with Sample Classificztions
Figure 7-3 Cross Section A-A’
List of Tables, Figures and Appendices
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Figure 7-4 Cross Section B-B’
Figure 7-5 Fines Content Data From Current and Previous Investigations
Figure 7-6 Gravel Content Data From Current and Previous Investigations
Figure 7-7 Blow Counts Data From Current and Previous Investigations
Figure 7-8 Gradation of 1903 Fill
Figure 7-9 Fines Content of Embankment and Foundation Materials
Figure 7-10 Gravel Content of Embankment and Foundation Materials
Figure 7-11 Atterberg Limits of Embankment and Foundation Materials
Figure 7-12 Water Content of Embankment and Foundation Materials
Figure 7-13 Dry Density of Embankment and Foundation Materials
Figure 7-14 Total Density of Embankment and Foundation Materials
Figure 7-15 Effective Stress Strength Data from Current and Previous Investigations
Figure 7-16 Total Stress Strength Data from Current and Previous Investigations
Figure 7-17 Effective Stress Strength of Embankment and Foundation Materials
Figure 7-18 Total Stress Strength of Embankment and Foundation Materials
Figure 7-19 Liquefaction Susceptibility Chart for Embankment and Foundation Materials
Figure 7-20 Gradation of 1938–1939 Fill
Figure 7-21 Gradation of Foundation Soil
Figure 9-1 Plan View of Analysis Section A-A’
Figure 9-2 Idealized Section A-A’ For Slope Stability Analysis
Figure 9-3 Modified Section A-A’ For Slope Stability Analysis
Figure 9-4 Slope Stability Analysis Long-Term Condition
Figure 9-5 Slope Stability Analysis Pre-Earthquake Condition
Figure 9-6 Slope Stability Analysis Selected Critical Sliding Blocks Section A-A’
Figure 9-7 Slope Stability Analysis Selected Critical Sliding Blocks Modified Section A-A’
Figure 10-1 Finite Element Mesh for Cross-Section A-A’, QUAD4M Analysis
Figure 10-2 Recorded Time History, 1989 Loma Prieta, CA Earthquake at Piedmont Jr. High
School Station, Horizontal Component, 045 deg.
Figure 10-3 Seismic Wave Velocity Profile and Stratigraphy from Borings B1, 2, and 3
Figure 10-4 Seismic Wave Velocity Profiles and Stratigraphy from Boring VQ-38
Figure 10-5 Seismic Wave Velocity Profile and Stratigraphy from Boring VQ-40
Figure 10-6 Selected Element Locations For Stress Time-history Plots QUAD4M Analysis
Figure 10-7 Selected Nodal Points For Acceleration Outputs QUAD4M Analysis
List of Tables, Figures and Appendices
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Figure 10-8 Sliding Blocks for Newmark Deformation Analyses Cross Section A-A’
Figure 10-9 Peak Horizontal Acceleration QUAD4M Analysis, 1989 Loma Prieta Earthquake
Figure 10-10 Average Mass Acceleration QUAD4M Analysis, 1989 Loma Prieta Earthquake
Figure 10-11 Peak Horizontal Acceleration, QUAD4M Analysis, Cross-Section A-A’, Hayward
Fault Event TH #1
Figure 10-12 Acceleration Time History, 175 FT Offset Upstream, QUAD4M Analysis,
Hayward Fault Event TH #1
Figure 10-13 Average Mass Acceleration, QUAD4M Analysis, Hayward Fault MCE TH #1
Figure 10-14 Shear Stress Time History Beneath Crest, Elements 465, 469, and 475, Hayward
Fault MCE TH #1
Figure 10-15 Peak Horizontal Acceleration, QUAD4M Analysis, Cross-Section A-A’, Hayward
Fault Event TH #2
Figure 10-16 Shear Stress Time History Beneath Crest, Elements 465, 469, and 475, Hayward
Fault MCE TH #2
Figure 10-17 Peak Horizontal Acceleration, QUAD4M Analysis, San Andreas Fault MCE
Figure 10-18 Shear Stress Time History Beneath Crest, Elements 465, 469, and 475, San
Andreas Fault MCE
Figure 11-1 Cyclic Strength and Undrained Strength Degradation of Saturated Embankment
Fills and Foundation Soils
Figure 11-2 Total Stress Strength Data from Post-Cyclic Consolidated Undrained Triaxial
Tests
Figure 11-3 Slope Stability Analysis Selected Critical Sliding Blocks Post-Earthquake
Conditions
Figure 11-4 Newmark Deformation Analysis, Calculated Displacement, U/S Block #1,
Hayward Fault MCE TH #1
Figure 11-5 Newmark Deformation Analysis, Calculated Displacement, D/S Block #2,
Hayward Fault MCE TH #1
Figure 11-6 Newmark Deformation Analysis, Calculated Displacement, D/S Block #3,
Hayward Fault MCE TH #1
Figure 11-7 Newmark Deformation Analysis, Calculated Displacement, U/S Block #1,
Hayward Fault MCE TH #2
Figure 11-8 Newmark Deformation Analysis, Calculated Displacement, C/S Block #2,
Hayward Fault Event TH #2
Figure 11-9 Newmark Deformation Analysis, Calculated Displacement, D/S Block #3,
Hayward Fault Event TH #2
Figure 11-10 Hayward-Rodgers Creek Fault MCE, Recommended Time History #3
List of Tables, Figures and Appendices
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Figure 11-11 Comparison of Acceleration Response Spectra for Hayward-Rodgers Creek Fault
MCE, Time History #3
Figure 11-12 Hayward-Rodgers Creek Fault MCE, Recommended Time History #4
Figure 11-13 Comparison of Acceleration Response Spectra for Hayward-Rodgers Creek Fault
MCE, Time History #4
Figure 11-14 Recorded Time History 1978 Tabas, Iran Earthquake at Tabas Station, Horizontal
Component, 344 deg.
Figure 11-15 1978 Tabas, Iran Earthquake at Tabas Station, Horizontal Component, 344
Degree
Figure 11-16 Recorded Time History 1989 Loma Prieta, CA Earthquake at UCSC – LGPC
Station, Horizontal Component, 000 deg.
Figure 11-17 1989 Loma Prieta, CA Earthquake at UCSC – LGPC Station, Horizontal 000 deg
Component
Figure 11-18 Simplified Newmark Analysis, Calculated Displacement, Assumed Ky = 0.05,
Hayward Fault MCE TH #1
Figure 11-19 Simplified Newmark Analysis, Calculated Displacement, Assumed Ky = 0.05,
Hayward Fault MCE TH #2
Figure 11-20 Simplified Newmark Analysis, Calculated Displacement, Assumed Ky = 0.05,
Hayward Fault MCE TH #3
Figure 11-21 Simplified Newmark Analysis, Calculated Displacement, Assumed Ky = 0.05,
Hayward Fault MCE TH #4
Figure 11-22 Simplified Newmark Analysis, Calculated Displacement, Assumed Ky = 0.05,
San Andreas Fault MCE
Figure 11-23 Simplified Newmark Analysis, Calculated Displacement, Assumed Ky = 0.05,
Tabas Earthquake, Tabas 344
Figure 11-24 Simplified Newmark Analysis, Calculated Displacement, Assumed Ky = 0.05,
Loma Prieta EQ, LGPC 000
Figure 11-25 Simplified Newmark Analysis, Calculated Displacement, Assumed Ky = 0.05,
Loma Prieta Earthquake
Figure 12-1 Finite Difference Mesh for Cross-Section A-A’, FLAC Analysis
Figure 12-2 FLAC Analysis, Pore Pressure Generation Model
Figure 12-3 Cyclic Strength and Undrained Strength Degradation of Saturated Embankment
Fills and Foundation Soils
Figure 12-4 FLAC Static Analysis, Downstream Slope, Pre-Earthquake Stability
Figure 12-5 FLAC Static Analysis Upstream Slope, Pre-Earthquake Stability
Figure 12-6 FLAC Static Analysis, Downstream Slope, Post-Earthquake Stability
Figure 12-7 FLAC Static Analysis, Upstream Slope, Post-Earthquake Stability
List of Tables, Figures and Appendices
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Figure 12-8 FLAC Dynamic Analysis with Assumed Strength Degradation, Permanent
Horizontal Displacement, Hayward MCE TH #1
Figure 12-9 FLAC Dynamic Analysis with Assumed Strength Degradation, Permanent
Vertical Displacement, Hayward MCE TH #1
Figure 12-10 FLAC Dynamic Analysis, Locations of Displacement, Time History
Figure 12-11 FLAC Dynamic Analysis with Assumed Strength Degradation, Horizontal
Displacement Time Histories, Hayward MCE TH #1
Figure 12-12 FLAC Dynamic Analysis with Assumed Strength Degradation, Vertical
Displacement Time Histories, Hayward MCE TH #1
Figure 12-13 FLAC Dynamic Analysis with Assumed Strength Degradation, Permanent
Horizontal Displacement, Hayward MCE TH #2
Figure 12-14 FLAC Dynamic Analysis with Assumed Strength Degradation, Permanent
Vertical Displacement, Hayward MCE TH #2
Figure 12-15 FLAC Dynamic Analysis with Assumed Strength Degradation, Horizontal
Displacement Time Histories, Hayward MCE TH #2
Figure 12-16 FLAC Dynamic Analysis with Assumed Strength Degradation, Vertical
Displacement Time Histories, Hayward MCE TH #2
Figure 12-17 FLAC Dynamic Analysis with Cyclic Degradation Model, Permanent Horizontal
Displacement, Hayward MCE TH #1
Figure 12-18 FLAC Dynamic Analysis with Cyclic Degradation Model, Permanent Vertical
Displacement, Hayward MCE TH #1
Figure 12-19 FLAC Dynamic Analysis with Cyclic Degradation Model, Deformed Mesh,
Hayward MCE TH #1
Figure 12-20 FLAC Dynamic Analysis with Cyclic Degradation Model, Horizontal
Displacement Time Histories, Hayward MCE TH #1
Figure 12-21 FLAC Dynamic Analysis with Cyclic Degradation Model, Vertical Displacement
Time Histories, Hayward MCE TH #1
Figure 12-22 FLAC Dynamic Analysis with Cyclic Degradation Model, Excess Pore Pressure
Ratio Contour, Hayward MCE TH #1
Figure 12-23 FLAC Dynamic Analysis with Cyclic Degradation Model, Cyclic Degradation
Contour, Hayward MCE TH #1
Figure 12-24 FLAC Dynamic Analysis with Cyclic Degradation Model, Locations of Cyclic
Degradation TH
Figure 12-25 FLAC Dynamic Analysis with cyclic Degradation Model, Cyclic Degradation
Time Histories, Hayward MCE TH #1
Figure 13-1 Isometric View of Dam Geometry and Sections A-A’ and C-C’
Figure 13-2 Isometric View of the 3-D Dam Model 3-D Slope Stability Analysis
List of Tables, Figures and Appendices
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Figure 13-3 Example of Interpolated Transverse Cross Section From CLARA 3-D Slope
Stability Analysis
Figure 13-4 Example of Interpolated Longitudinal Cross Section From CLARA 3-D Slope
Stability Analysis
Figure 13-5 Profile of Critical 3-D Sliding Block on Cross-Section A-A’, 3-D Slope Stability
Analysis, Post-Earthquake Conditions
Figure 13-6 Profile of Critical 3D Sliding Block on Cross Section C-C’, 3-D Slope Stability
Analysis, Post-Earthquake Conditions
Figure 13-7 Profile of Critical 3-D Sliding Block on Longitudinal Section at Offset = 0, 3-D
Slope Stability Analysis
Figure 13-8 Profile of Critical 3-D Sliding Block on Longitudinal Section at Offset = 40 ft, 3-
D Slope Stability Analysis
Figure 13-9 Profile of Critical 3-D Sliding Block on Longitudinal Section at Offset = 110 ft,
3-D Slope Stability Analysis
Figure 13-10 Finite Element Mesh for QUAD4M Analysis, Cross-Section A-A’ and Critical 3-
D Sliding Surface
Figure 13-11 Finite Element Mesh for QUAD4M Analysis, Additional Cross-Section C-C’ and
Critical 3-D Sliding Surface
Figure 13-12 Average Seismic Coefficient Downstream Blocks, QUAD4M Analysis, Hayward
Fault MCE TH #1
Figure 13-13 Average Seismic Coefficient Downstream Blocks, QUAD4M Analysis, Hayward
Fault MCE TH #2
Figure 13-14 Newmark Deformation Analysis, Calculated Displacement, Critical 3-D D/S
Sliding Block, Hayward Fault MCE TH #1
Figure 13-15 Newmark Deformation Analysis Calculated Displacement, Critical 3-D D/S
Sliding Block, Hayward Fault MCE TH #2
VOLUME 2
Appendices
Appendix A Exploratory Drilling
Appendix B SPT Energy Measurements
Appendix C Downhole Geophysical Survey
Appendix D Laboratory Testing
Appendix E Site Geology
Appendix A Exploratory Drilling
Specific gravityHydrometer analysis, percent passing 5 micronsLiquid Limit (from Atterberg Limits test), percentPlasticity Index (from Atterberg Limits test), percentSieve analysis, percent passing #200 sieveIsotropically consolidated undrained triaxial test
Percentage of driven or pushed sample lengthrecovered; "NA" indicates data not recorded.Recovery:
Dry weight per unit volume of soil measured inlaboratory, expressed in pounds per cubic feet (pcf).
GENERAL NOTES
81
Type of sample collected at depth interval shown;sampler symbols are explained below.
Description of material encountered; mayinclude relative density / consistency, moisture, color, and grain size.
Comments and observations regardingdrilling or sampling made by driller or field personnel. Other field andlaboratory test results, using the following abbreviations:
Material Description:1
2
CLAY (CH)
SILT (MH)
5
CLAYEY SILT (ML)
CLAY (CL)
SILTY SAND (SM)
GsHDLLPISATX-CIU(R)
10
9
POORLY GRADED SANDWITH SILT (SP-SM)
COLUMN DESCRIPTIONS
Elevation in feet referenced to mean sea level (MSL)or site datum.
Sample Type:
1095
Depth:
Elevation:
4 Sample Number:
8
3
643
Water content of soil sample measured inlaboratory, expressed as percentage of dry weight of specimen.
Graphic Log:
2
1. Soil classifications are based on the Unified Soil Classification System. Descriptions and stratum lines are interpretive; actuallithologic changes may be gradual. Field descriptions may have been modified to reflect results of lab tests.
2. Descriptions on these logs apply only at the specific boring locations and at the time the borings were advanced. They arenot warranted to be representative of subsurface conditions at other locations or times.
7
Dry Unit Weight:
Sampling Resistance:
6
Graphic depiction of subsurface materialencountered; typical symbols are explained below.
Number of blows required to advancedriven sampler 12 inches beyond first 6-inch drive interval, ordistance noted, using a 140-lb hammer with a 30-inch drop;hydraulic down-pressure for tube sampler.
11
11Sample identification number. "NR"
following sample number indicates no recovery. Remarks and Other Tests:
7
Depth in feet below the ground surface. Water Content:
Re
po
rt:
GE
O_
10
B1
A_
OA
K_
KE
Y;
F
ile:
OA
K_
ES
TA
TE
SD
AM
.GP
J;
6
/17
/20
05
k
eyd
am
Key to Log of BoringProject Location: Piedmont, Alameda County, California
Project: Dynamic Stability of Estates Dam
SAMPLES
Project Number: 26814957
Gra
phic
Log
Recovery
, %
Sam
plin
gR
esis
tance
Ele
vation
feet
Depth
,fe
et
Type
REMARKS AND
OTHER TESTS
Sheet 1 of 2
Num
ber
Dry
Un
itW
eig
ht,
pcf
Wa
ter
Co
nte
nt,
%
MATERIAL DESCRIPTION
SILT (ML)
Pitcher Barrel (4-inch-OD)with Shelby tube liner
Pitcher Barrel (3-inch-OD)with Shelby tube liner
SILTY CLAY (CL)WELL-GRADED SAND(SW)
HQ rock core barrel
GRAVEL (GP/GW)
POORLY GRADED SAND(SP)
CLAYEY SAND (SC)
TYPICAL MATERIAL GRAPHIC SYMBOLS
META-SANDSTONE /GRAYWACKE
META-VOLCANIC ROCKSHALE / CLAYEY SHALESANDSTONE
Static water level measured after drilling andsampling completed
4
3
Figure A-1
OTHER GRAPHIC SYMBOLS
Standard Penetration Test(SPT) unlined split spoon(1.4-inch-ID)
First water encountered at time of drilling andsampling (ATD)
Modified California(2.5-inch-ID) with brassliners
Grab or bulk sample fromcuttings
Inferred or transitional contact between lithologies
Change in material properties within a lithologicstratum
TYPICAL SAMPLER GRAPHIC SYMBOLS
W
Slightly Weathered/Altered
minimum 2-inch-diameter sample cannot be broken readily by hand across rock fabric
Completely Weathered/Altered
Rock shows no discoloration, loss of strength, or other effect of weathering/alteration
ROCK WEATHERING / ALTERATION
Moderately Weathered/Altered
original rock fabric is not apparent; material can be easily broken by hand
Description
Highly Weathered/Altered
b
a
ROCK FRACTURING
Aperture (inches):
N- Moderately Wide (0.1-0.5)
J
MW- Wide (0.5-2.0)
c
- Narrow (0.05-0.1)
Moderately Strong Rock
Recognition
g
Type of Infilling:
B
- Joint
- Very Rough [near-vertical steps andridges occur on discontinuity surface]
VR
- Rough [ridges and side-angle stepsare evident; asperities are clearlyvisible; surface feels very abrasive]
R
- Slightly Rough [asperities ondiscontinuity surfaces aredistinguishable and can be felt]
SR
- Smooth [surface appears smoothand feels so to the touch]
Roughness of Surface:
Original minerals of rock have been entirely decomposed to secondary minerals, and
- Slickensided [surface has smooth,glassy finish with visual evidenceof striations]
Slk
Dip of discontinuity, measured relative to a plane normal to the core axis.
FeCh
- Clay
Recognition
- Iron Oxide
S
- Healed
Rock is discolored and noticeably weakened, but less than half is decomposed; a
2-inch-diameter sample can be broken readily by hand across rock fabric
- Foliation
- Unknown- SandSd
- PyritePy
Weak Rock
No
Residual Soil
H
Uk
DISCONTINUITY DESCRIPTORS
Figure A-1 (contd)
- None
- Surface Stain
- Chlorite- CalciteCa
Cl
ROCK STRENGTH
VN- Stepped
e Amount of Infilling:
Fresh/Unweathered
- Spotty
Rock is slightly discolored, but not noticeably lower in strength than fresh rock
Surface Shape of Joint:
- Filled
Wa - Wavy
f
- PlanarPl
- Fault
- Bedding
Fo
Sp
Project: Dynamic Stability of Estates Dam
Project Number: 26814957
Project Location: Piedmont, Alameda County, CaliforniaSheet 2 of 2
Extremely Weak Rock
Cannot be scratched with pocket knife; knife marks are left on surface
Key to Log of Boring
Recognition
Fractures spaced 2 inches to 1 foot apart
Description
Strong Rock
Can be readily scratched by knife blade; scratch leaves heavy trace
Re
po
rt:
GE
O_
CO
RE
_K
EY
_P
2_
AB
BR
EV
3;
F
ile:
OA
K_
ES
TA
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SD
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.GP
J;
6
/17
/20
05
k
eyd
am
Hard
Moderately Hard
RQD: Rock Quality Designation; defined as the percent of intact core (pieces of sound core greater than 102 mm in length) ineach coring interval; calculated as the sum of the lengths of intact core divided by the length of the core run.
Very Hard
Low Hardness
Friable
KEY TO DESCRIPTIVE TERMS FOR ROCK
produces little powder; traces of knife steel may be visible
ROCK SCRATCH HARDNESS
Can be gouged deeply or carved with a pocket knife
Easily crumbled by hand; too soft to cut with a pocket knife
Can be scratched with a pocket knife only with difficulty; scratch
of dust and is readily visible after powder has been blown away
Applicable only to plastic material
Description Recognition
Discontinuity Type:
Soft
Extremely Strong Rock
Fi
Su
More than half of the rock is decomposed; rock is weakened so that a minimum
although original fabric may be intact; material can be granulated by handOriginal minerals of rock have been almost entirely decomposed to secondary minerals,
- Irregular
- Quartz
Fractures spaced less than 2 inches apart
Fracture spacing greater than 10 feet
Pa
Fractures spaced 1 foot to 3 feet apart
Can be indented 5 mm with sharp end of pick
Can be indented by thumbnail
Can be peeled with difficulty by pocket knife
Can only be chipped with hammer blows
Requires many hammer blows to fracture
Requires one hammer blow to fracture
Can be peeled by pocket knife
StIr
Fractures spaced 3 feet to 10 feet apart
F
Very Weak Rock
Qz
Slightly Fractured
Massive
Moderately Fractured
Highly Fractured
Intensely Fractured
Description
Sh - Partially Filled
Very Strong Rock
- Vein
- Tight (0)
- Shear
T
d
V - NoneNo
- Very Narrow (<0.05)
CLAYEY SAND WITH GRAVEL (SC) [Fill]Medium dense, very moist, bluish gray, ~30% fines, ~30% gravel
67
100
97
87
Becomes yellowish brown and gray
Sam
plin
gR
esis
tance,
blo
ws / foot
1
SAMPLESG
raphic
Log
17.417.217.3
17.2
19.5
21.0
67
With clasts of black silty clay
94
53
50
100 psi
Becomes moist, bluish gray and brown to yellowish brown, ~40% fines,~15% gravel
115.4
116.2
111.0
101.3
3
4
3
4
10
100 psi
Start at 07:40.
100 psi
LL=47, PI=26
12
21
700 psi
9A
9B
8
7A7B7C
6
5
4A
4B
3A3B
2
12
TX-CIU(R)
CLAYEY SAND (SC) [Fill]Medium dense, moist, grayish brown, fine- to medium-grained sand,~45% fines, ~10% gravel
SANDY CLAY (CL) [Fill]Stiff to very stiff, slightly moist to moist, olive gray, medium plasticity fines,~30-40% sand, ~5-10% gravel
CLAYEY GRAVEL (GC) [Fill]Medium dense, very moist, olive gray, fine gravel, ~30% fines
Gravel grades coarser, trace clasts of dark gray to black clay
CLAYEY SAND WITH GRAVEL (SC) [Fill]Moist, olive and brown, ~40% medium plasticity fines, ~25% fine gravel,mixed texture
Asphaltic concrete 1 inch thick over 6 inches fine gravel (crushed rhyolite?)
Driller uses polymer tostabilize circulation29-30 ft.
SA: %F=40, %G=12
Fluid level drops to18.6 ft bgs followingPitcher sampling;measured at 21.0 ft after30 minutes.
HD: 23%<5 micronsSA: %F=44, %G=10
115.1LL=35, PI=17
HD: 26%<5 micronsSA: %F=49, %G=11Gs=2.761
HD: 25%<5 micronsSA: %F=45, %G=13TX-CIU(R)
TX-CIU(R)HD: 29%<5 micronsSA: %F=52, %G=6LL=36, PI=18
SA: %F=40, %G=25
TX-CIU(R)
770
765
760
755
750
745
Logged By
BoreholeBackfill
Project: Dynamic Stability of Estates Dam
Automatic trip hammer;140 lbs, 30-inch drop
Drill RigType
DrillingContractor
GroundwaterLevel (s)
Re
po
rt:
GE
O_
10
B1
A_
OA
K;
F
ile:
OA
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.GP
J;
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/17
/20
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V
Q-3
7
Figure A-2
Log of Boring VQ-37
Sheet 1 of 2
0
5
10
15
20
25
30
Project Number: 26814957
Project Location: Piedmont, Alameda County, CaliforniaE
levation,
feet
Num
ber
57.5 feet
4/6/05
HammerData
Wa
ter
Co
nte
nt,
%
T. Feldsher
Total Depthof Borehole
Type
Dry
Un
itW
eig
ht,
pcf
MATERIAL DESCRIPTION REMARKS ANDOTHER TESTS
Depth
,fe
et
Recovery
, %
5-7/8-inch tri-cone bit
Portland cement grout Location
SamplingMethod(s)
DrillingMethod
Date(s)Drilled
SurfaceElevation
Drill BitSize/Type
M. McKee
Crest of Dam, approx. 17.5 feet W of VQ-33, 8.5 feet S of building wall
Pitcher Drilling Company
Checked By
Not measured due to drilling method
Rotary Wash
Fraste Multi-Drill XL
Grab, SPT, Modified California,Pitcher Barrel (3- and 4-inch-OD)
approx. 774 feet MSL
14
73
50
50
11
10
12A
80
META-SANDSTONE / GRAYWACKE [Franciscan Complex Bedrock]Gray, highly to moderately weathered, weak, moderately hard, intenselyfractured
13
100
67
87
12B
280 psi
1440 psi
3
4
3
4
100 psi
450 psi
700 psi
Driller notes drillingsticky, clayey at 34 ft.
27
100 psi
150 psi
840 psi
16
15 31
Drilling under rod weightat 51 ft.
20.4
CLAYEY SHALE [Franciscan Complex Bedrock]Black, highly weathered, very weak, intensely fractured
Becomes clayey, completely to highly weathered, very weak
META-VOLCANIC ROCK [Franciscan Complex Bedrock]Reddish brown and yellowish brown, moderately weathered, weak, lowhardness, intensely fractured, clay infilling in one narrow vertical fracture
SANDY CLAY (CL) [Native Soil]Very stiff, moist, yellowish brown with gray mottling, medium plasticity
SANDY SILTY CLAY (CL) [Fill]Stiff, moist, dark grayish brown to grayish brown, medium plasticity fines,~35% sand, ~5-10% fine gravel (angular meta-sandstone fragments),trace clasts of black to very dark gray clay (high plasticity)
3
End drilling at 13:30;complete grouting at14:40.
114.2
Pitcher barrel cuts fasterin last 6 inches.
SA: %F=66, %G=0LL=40, PI=22
SA: %F=53, %G=10LL=32, PI=16TX-CIU(R)
Bottom of boring at 57.5 feet
CLAYEY GRAVEL WITH SAND (GC) [Fill]Medium dense, very moist, bluish gray, trace clasts of dark gray to blackclay
Project: Dynamic Stability of Estates Dam
Project Location: Piedmont, Alameda County, California
30
35
40
45
50
55
60
65
740
735
730
725
720
715
710
17.8
Project Number: 26814957
Re
po
rt:
GE
O_
10
B1
A_
OA
K;
F
ile:
OA
K_
ES
TA
TE
SD
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.GP
J;
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/17
/20
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V
Q-3
7
Figure A-2
Log of Boring VQ-37
Sheet 2 of 2
Sam
plin
gR
esis
tance,
blo
ws / foot
Dry
Un
itW
eig
ht,
pcf
MATERIAL DESCRIPTION REMARKS ANDOTHER TESTS
Num
ber
SAMPLES
Gra
phic
Log
Depth
,fe
et
Wa
ter
Co
nte
nt,
%
Recovery
, %
Ele
vation,
feet
Type
18.2
93
100
100
56
100
90
33
97
55
Gra
phic
Log
Dry
Un
itW
eig
ht,
pcf
1
REMARKS ANDOTHER TESTS
Depth
,fe
et
Num
ber
Sam
plin
gR
esis
tance,
blo
ws / foot
SAMPLES
19.5
11.0
100 psito
140 psi
3
4
3
140 psi
100 psi
8
12
100 psi
700 psi400 psi
400 psi
3
29 127.5
10
9
8
7A7B
6
5
4
3B3A
2
17
SANDY CLAY WITH GRAVEL (CL/CH) [Fill]Very stiff, moist to very moist, yellowish brown to olive brown and gray,medium to high plasticity fines, ~30% sand, ~15% fine to coarse gravel,mixed texture
CLAYEY SAND WITH GRAVEL (SC) [Fill]Medium dense, moist to very moist, bluish gray and olive, fine- tocoarse-grained sand, ~25-30% fines, ~35% fine to coarse gravel
Possible cobble-size rock fragments
SANDY CLAY (CL) [Fill]Stiff, moist, yellowish brown and gray,
low to medium plasticity fines, few fine to coarse gravel, iron oxide-stainedcoarse-grained sand and sandstone fragments to 1/4 inch dia.
Becomes olive to olive brown, with clasts of black silty clay; decreasinggravel content (~5%)
SANDY CLAY WITH GRAVEL (CL) [Fill]Very stiff, moist, yellowish brown, gray, olive, and bluish gray, low tomedium plasticity fines, ~30-35% fine- to medium-grained sand,~15% fine gravel (includes serpentinite fragments), trace silt, mixedtexture
4
CLAYEY GRAVEL WITH SAND (GC) [Fill]Medium dense, very moist, olive and gray, fine to coarse gravel,~25% fines, ~30% sand, mixed texture
Asphaltic concrete 1-1/2 inches thick over 8 inches subangular gravel(crushed meta-volcanic rock)
Rocky drilling at27-27.75 ft.
SA: %F=54, %G=12LL=36, PI=20TX-CIU(R)
Coarse gravel stuck inSPT sampler shoe.
SA: %F=25, %G=46LL=37, PI=20
Start at 08:30 on 3/28/05.Pavement cored with6-inch barrel. Used6-inch auger to 2.5 ft,then switched to rotarywash drilling.
111.2
CLAYEY SAND WITH GRAVEL (SC) [Fill]Medium dense, very moist, yellowish brown and gray, ~25% fines,~25% gravel (chert, rhyolite, and quartzite fragments)
0
5
10
15
20
25
30
770
765
760
755
750
745
DrillingContractor
Project Number: 26814957
BoreholeBackfill
Automatic trip hammer;140 lbs, 30-inch drop
Drill RigType
MATERIAL DESCRIPTION
Re
po
rt:
GE
O_
10
B1
A_
OA
K;
F
ile:
OA
K_
ES
TA
TE
SD
AM
.GP
J;
6
/17
/20
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V
Q-3
8
Figure A-3
Log of Boring VQ-38
Sheet 1 of 3
Project: Dynamic Stability of Estates Dam
Project Location: Piedmont, Alameda County, California
GroundwaterLevel (s)
HammerData
approx. 774 feet MSL
Rotary Wash
Checked By T. Feldsher
Total Depthof Borehole
3/28/05 and 3/29/05
Fraste Multi-Drill XL
Wa
ter
Co
nte
nt,
%
Recovery
, %
Ele
vation,
feet
Type
Drill BitSize/Type 87.0 feet
Logged By
Portland cement grout Location
SamplingMethod(s)
DrillingMethod
SurfaceElevation
M. McKee
Crest of Dam, approx. 12.5 feet E of VQ-32, 8.5 feet S of building wall
Pitcher Drilling Company
Grab, SPT, Mod. California, PitcherBarrel (3- and 4-in.); HQ core barrel
5-7/8-inch tri-cone bit; HQ core bit
Not measured due to drilling method
Date(s)Drilled
SANDY SILTY CLAY (CL) [Weathered Serpentinite / Native Soil?]Very stiff, moist, black with green mottling, possibly organic, low tomedium plasticity fines, ~40% sand, trace serpentinite fragments to1/4 inch dia.
Becomes black, weak to moderately strong
CLAYEY SHALE [Franciscan Complex Bedrock]Dark grayish brown to black, highly weathered, very weak to weak, lowhardness, intensely fractured, sheared
CLAY (CL/CH) [Native Soil / Residual]Hard, olive brown, moist to very moist, medium to high plasticity, trace finegravel (shale fragments), trace carbonate nodules
10
POORLY GRADED SAND (SP) [Serpentinite Clast?]Bluish gray, fine- to medium-grained sand (cuttings observed duringPitcher sampling)
Becomes dense, very moist, bluish gray with clasts of yellowish brownclay, ~30-40% fines, ~15% gravel (sandstone and serpentinitefragments)
Becomes olive to olive brown with gray fine gravel (serpentinitefragments) and clasts of brown sandy clay
CLAYEY SAND WITH GRAVEL (SC), medium dense, moist to very moist,bluish gray and olive, fine- to coarse-grained sand, ~25-30% fines,~35% fine to coarse gravel [Fill] (continued)
3.5-ft run; RQD=0%.
2.0-ft run; RQD=0%.
5.0-ft run; RQD=0%.
End drilling for 3/28/05.Resume drilling 3/29/05using HQ core bit andbarrel.
HD: 37%<5 micronsSA: %F=64, %G=0
SANDY CLAY (CL) [Native Soil / Colluvium]Very stiff, moist to very moist, gray to olive brown, medium plasticity
100
60
0
89
100
77
0
70
93
Gs=2.713
Run 3
LL=36, PI=18
3
50/5.5"
100 psito
140 psi
600 psi
700 psi
28
100 psi
420 psi
12
3
140 psi
4
Run 2
Run 1
17A17B
16
[NR]
15A15B
14
13
12
11A11B
29
LL=29, PI=13
94
Hard material at 49.5 ft.Tip of sampler badly torn.Drill to 52 ft to attemptPitcher sampling again.
SA: %F=60, %G=4LL=31, PI=14TX-CIU(R)
Driller reports smoothersampling at 44 ft.
HD: 20%<5 micronsSA: %F=38, %G=16LL=29, PI=134
TX-CIU(R)
TX-CIU(R)
HD: 17%<5 micronsSA: %F=34, %G=16Gs=2.775
SA: %F=26, %G=34
114.8
118.9
124.0132.5
136.5
4
TX-CIU(R)
Recovery
, %
Project Location: Piedmont, Alameda County, California
Project: Dynamic Stability of Estates Dam
30
35
40
45
50
55
60
65
740
735
730
725
720
715
710
Wa
ter
Co
nte
nt,
%
20
Re
po
rt:
GE
O_
10
B1
A_
OA
K;
F
ile:
OA
K_
ES
TA
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SD
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.GP
J;
6
/17
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V
Q-3
8
Figure A-3
Log of Boring VQ-38
Sheet 2 of 3Project Number: 26814957
14.1
10.611.8
9.3
85
15.8
REMARKS ANDOTHER TESTS
Ele
vation,
feet
Type
13.8
MATERIAL DESCRIPTION
15.1
Depth
,fe
et
Num
ber
Sam
plin
gR
esis
tance,
blo
ws / foot
SAMPLES
Gra
phic
Log
17.816.8
Dry
Un
itW
eig
ht,
pcf
88
80
100
94
96
85
Run 3
86
3.5-ft run; RQD=0%.
End drilling at 15:12 on3/29/05.
2.0-ft run; RQD=50%.
Core barrel blocked off;stop run.
3.0-ft run; RQD=46%.
Fluid loss of ~10 gal. at83-84 ft.
5.0-ft run; RQD=28%.
4.0-ft run; RQD=0%.
2.5-ft run; RQD=0%.SHALE interbed, completely to highly weathered, intensely fractured,68.5-68.8 ft
Run 9
Run 8
Run 7
Run 6
Run 5
Run 4
3.0-ft run; RQD=0%.
SANDSTONE [Franciscan Complex Bedrock]Gray, fine-grained, slightly weathered, weak, moderately hard, intenselyfractured; discrete fractures dipping 15-45°, very narrow, no infilling,planar, slightly rough surfaces
Bottom of boring at 87.0 feet
Downhole OYO suspension logging performed in uncased hole, thenborehole backfilled with cement grout.
Sandstone grades fine- to medium-grained
CLAYEY SHALE, black, highly weathered, very weak,intensely fractured
Calcite vein, very narrow
CLAYEY SHALE, black, highly weathered, weak to moderately strong, lowhardness, intensely fractured [Bedrock] (continued)
Quartz vein, moderately wide to wide
SANDSTONE [Franciscan Complex Bedrock]Gray, fine-grained, slightly weathered, strong to very strong, hard, quartzvein to 1/2 inch wide, intensely to highly fractured; discrete fracturesdipping 15-50°, very narrow, no infilling or partial clay infilling, planar toirregular, slightly rough surfaces
CLAYEY SHALE [Franciscan Complex Bedrock]Dark gray to black, highly weathered, very weak, intensely fractured, tracecalcite veins to 0.1 inch wide; discrete fractures dipping 10-55°, verynarrow to narrow, partially filled with calcite or clay, planar, smooth toslightly rough surfaces
CLAYEY SHALE, dark grayish brown, completely to highly weathered,very weak, soft, intensely fractured
Sandstone becomes highly to moderately weathered, very weak to weak,moderately hard, highly to moderately fractured
CLAYEY SHALE, dark grayish brown, completely to highly weathered,very weak, soft, intensely fractured
75°, J, N, Cl, Pa, Pl, SR
CLAYEY SHALE, very weak, soft, intensely fractured
50°, J, VN, Cl, Pa, Pl, SR
SHALE interbed, dark gray, very weak, soft, intensely fractured
Project Number: 26814957
Project Location: Piedmont, Alameda County, California
Project: Dynamic Stability of Estates Dam
65
70
75
80
85
90
95
100
705
700
695
690
685
680
675
Re
po
rt:
GE
O_
10
B1
A_
OA
K;
F
ile:
OA
K_
ES
TA
TE
SD
AM
.GP
J;
6
/17
/20
05
V
Q-3
8
Figure A-3
Log of Boring VQ-38
Sheet 3 of 3
SAMPLES
Gra
phic
Log
Recovery
, %
Ele
vation,
feet
Type
Wa
ter
Co
nte
nt,
%
Dry
Un
itW
eig
ht,
pcf
MATERIAL DESCRIPTION REMARKS ANDOTHER TESTS
Depth
,fe
et
Num
ber
Sam
plin
gR
esis
tance,
blo
ws / foot
84
100
72
70
78
80
76
56
SAMPLES
1
Dry
Un
itW
eig
ht,
pcf
MATERIAL DESCRIPTION REMARKS ANDOTHER TESTS
Depth
,fe
et
Num
ber
Sam
plin
gR
esis
tance,
blo
ws / foot
Gra
phic
Log
16.9
15.1
160 psi
840 psi
3
4
3
4
3
140 psi
900 psi
18
140 psi
16
116.2
22
Start at 10:30.
100 psi
420 psi
9
8A8B8C
7
6
5
4B4A
3
2
140 psi
SILTY CLAY WITH SAND (CH) [Fill]Stiff, moist, olive, yellowish brown, and grayish brown, high plasticityfines, ~20% sand, ~5% fine gravel, mixed texture
CLAYEY SHALE [Franciscan Complex Bedrock]Olive and dark gray, completely to highly weathered, very weak to weak,low hardness, intensely fractured
CLAY WITH SAND (CH) [Native Soil / Colluvium]Stiff, moist, dark bluish gray, high plasticity fines, fine-grained sand, tracebasalt / meta-volcanic fragments to 1/4 inch dia., trace rootlets
CLAYEY SAND (SC) [Fill]Medium dense, moist, gray to bluish gray and brown, fine- tomedium-grained sand, ~45% low plasticity fines, ~10-15% fine gravel
SILTY CLAY WITH SAND (CL) [Fill]Stiff to very stiff, moist, yellowish brown and gray grading to dark grayishbrown, medium plasticity fines, ~20% sand, ~5-10% fine gravel
SANDY CLAY / CLAYEY SAND WITH GRAVEL (CL/SC) [Fill]Stiff / medium dense, very moist, bluish gray, fine- to coarse-grainedsand, ~20-25% fine gravel
114.2
Becomes grayish yellow to pale yellow; increasing gravel content
Asphaltic concrete 1 inch thick over 3 inches gravel/crushed rock
Harder drilling at 27.2 ft.
SA: %F=47, %G=13LL=30, PI=12
Fluid level at 8.7 ft bgsafter sampling, 11.5 ftafter 10 min. Resumedrilling with polymeradded to drilling fluid.
Fluid loss of ~30 gal.during Pitcher sampling.
Drilling softer at 16 ft.
SA: %F=26, %G=31LL=36, PI=19TX-CIU(R)CLAYEY SAND WITH GRAVEL (SC) [Fill]
Medium dense, moist, grayish yellow to pale yellow, fine- to coarse-grained sand, ~25% medium plasticity fines, ~30% fine to coarse gravel(meta-volcanic fragments)
0
5
10
15
20
25
30
755
750
745
740
735
730
725
Project Location: Piedmont, Alameda County, California
Project Number: 26814957
BoreholeBackfill
Automatic trip hammer;140 lbs, 30-inch drop
Re
po
rt:
GE
O_
10
B1
A_
OA
K;
F
ile:
OA
K_
ES
TA
TE
SD
AM
.GP
J;
6
/17
/20
05
V
Q-3
9
Figure A-4
Log of Boring VQ-39
Sheet 1 of 2
Project: Dynamic Stability of Estates Dam
DrillingContractor
HammerData
Drill RigType approx. 755 feet MSL
Rotary Wash
Checked By T. Feldsher
Total Depthof Borehole
4/7/05
Wa
ter
Co
nte
nt,
%
Recovery
, %
Ele
vation,
feet
Type
SurfaceElevation
GroundwaterLevel (s)
35.7 feet
Logged By
Portland cement grout Location
SamplingMethod(s)
Date(s)Drilled
Fraste Multi-Drill XL
Drill BitSize/Type
M. McKee
Downstream bench road, 51.5 feet W of VQ-40, 7 feet S of bench wall
Pitcher Drilling Company
Grab, SPT, Modified California,Pitcher Barrel (3- and 4-inch-OD)
5-7/8-inch tri-cone bit
Not measured due to drilling method
DrillingMethod
Sam
plin
gR
esis
tance,
blo
ws / foot
Num
ber
Depth
,fe
et
REMARKS ANDOTHER TESTS
MATERIAL DESCRIPTION
Dry
Un
itW
eig
ht,
pcf
Type
Ele
vation,
feet
Recovery
, %
10
Wa
ter
Co
nte
nt,
%
11
1600 psi
45/2"
4
CLAYEY SHALE [Franciscan Complex Bedrock], olive and dark gray,completely to highly weathered, very weak to weak, low hardness, intenselyfractured (continued)
BASALT / META-VOLCANIC ROCK [Franciscan Complex Bedrock]Dark yellowish brown to reddish brown, completely to highly weathered,very weak, low hardness
56
100
Gra
phic
Log
SAMPLES
Bottom of boring at 35.7 feet
Sheet 2 of 2
Log of Boring VQ-39
Figure A-4Re
po
rt:
GE
O_
10
B1
A_
OA
K;
F
ile:
OA
K_
ES
TA
TE
SD
AM
.GP
J;
6
/17
/20
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V
Q-3
9
725
720
715
710
705
700
695
690
30
35
40
45
50
55
60
65
Project: Dynamic Stability of Estates Dam
Project Location: Piedmont, Alameda County, California
Project Number: 26814957
100
52
58
100
93
61
87
12.0
Num
ber
1
SAMPLESG
raphic
Log
16.3
14.0
86
9.3
CLAYEY SAND / SANDY CLAY WITH GRAVEL (SC/CL) [Fill]Medium dense / stiff, moist, very dark gray and black, ~40-45% fine- tomedium-grained sand, ~40-50% low plasticity fines, ~10-20% gravel
11.3
100 psito
140 psi 130.2135.5
4
3
4
3
4
140 psi
<100 psi
5
300 psi600 psi
Hammer energymeasurements taken fordrive samples in thisboring.
20
420 psi
500 psi
9
8
7
6B6A
5
4
3
2
9
Gravelly drilling at 28 ft.
Depth
,fe
et
CLAY WITH SAND (CL/OL) [Fill]Stiff, moist, very dark gray and black, faintly mottled, organic tosemi-organic, ~20% sand, <5% fine gravel
SANDY CLAY (CL) [Fill]Medium stiff, very moist, yellowish brown, low plasticity fines,~30-35% sand, ~10% fine gravel
CLAYEY GRAVEL (GC) [Fill]Medium dense, moist, dark yellowish brown, ~15-20% fines, ~10% sand
CLAYEY SAND WITH GRAVEL (SC) [Fill]Medium dense, moist, yellowish brown to olive brown, fine- tocoarse-grained sand, ~30-35% medium plasticity fines, ~20-25% fine to coarse gravel
With clasts of yellowish brown and gray clay to 2 inches dia.
Gravel grades coarse (basalt fragments to 2 inches)
SANDY CLAY (CL) [Fill]Stiff to very stiff, moist, yellowish brown to olive brown, low plasticity fines,~40% sand, ~5% fine gravel
Asphaltic concrete 1/2 inch thick over 4 inches clayey gravel
TX-CIU(R)HD: 25%<5 microns
114.5
LL=28, PI=10
Start at 10:35 on 3/30/05.Pavement cored with6-inch barrel. Used6-inch auger to 2.5 ft,then switched to rotarywash drilling.
Gravelly drilling at 22.5 ft.
Drill past obstruction;very easy drilling at 17 ft.
Fluid loss of ~40 gal. at15.5-16 ft during Pitchersampling. Refusal(cobbles) at 15.75 ft; tipof tube bent.
SA: %F=36, %G=19LL=34, PI=17TX-CIU(R)TX-CIU(R)LL=32, PI=16SA: %F=30, %G=25Gs=2.762
SA: %F=50, %G=11
BoreholeBackfill
745
740
735
730
725
720
Sam
plin
gR
esis
tance,
blo
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Project Location: Piedmont, Alameda County, California
Automatic trip hammer;140 lbs, 30-inch drop
Drill RigType
DrillingContractor
GroundwaterLevel (s)
Re
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GE
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A_
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K;
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OA
K_
ES
TA
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.GP
J;
6
/17
/20
05
V
Q-4
0
Figure A-5
Log of Boring VQ-40
Sheet 1 of 3
0
5
10
15
20
25
30
Project: Dynamic Stability of Estates Dam
Project Number: 26814957
Logged By
72.0 feet
Checked By
Total Depthof Borehole
3/30/05 and 3/31/05
HammerData
approx. 747 feet MSL
Rotary Wash
Recovery
, %
Ele
vation,
feet
Type
Dry
Un
itW
eig
ht,
pcf
MATERIAL DESCRIPTION
Wa
ter
Co
nte
nt,
%
Pitcher Drilling Company
REMARKS ANDOTHER TESTS
Portland cement grout Location
SamplingMethod(s)
DrillingMethod
Date(s)Drilled
SurfaceElevation
Drill BitSize/Type
T. Feldsher
Downstream bench, approx. 5 feet W of boring B6, 7 feet S of bench wall
Grab, SPT, Mod. California, PitcherBarrel (3- and 4-in.); HQ core barrel
5-7/8-inch tri-cone bit; HQ core bit
Not measured due to drilling method
Fraste Multi-Drill XL
M. McKee
14
CLAYEY SHALE [Franciscan Complex Bedrock]Gray to black, completely to highly weathered, very weak, soft to lowhardness
36
11
9
12
13
84
67
100
80
89
83
86
Gray, more clayey, completely weathered, some calcite crystals
38
87/6"
CLAYEY SANDSTONE [Franciscan Complex Bedrock]Gray to bluish gray, medium-grained, completely to moderatelyweathered, very weak to weak, low hardness to moderately hard, intenselyfractured
SA: %F=38, %G=17LL=30, PI=11TX-CIU(R)Gs=2.668
117.5
121.2
4
End drilling for 3/30/05at 38 ft.
4
Resume on 3/31/05.
300 psi420 psi600 psi
140 psi
300 psito
400 psi
22
20
350 psi
Run 3
Run 2
Run 1
3
4.5-ft run; RQD=0%.
CLAYEY SHALE [Franciscan Complex Bedrock]Black, some sand, highly weathered, very weak, low hardness, intenselyfractured; steeply dipping quartz vein in core at 52.7 ft
Becomes bluish gray, moderately weathered, weak, low hardness tomoderately hard
Becomes weak to moderately strong, moderately hard
Becomes weak, highly to moderately weathered
CLAYEY SANDSTONE [Franciscan Complex Bedrock]Olive brown, fine- to medium-grained, ~30-35% fines, highly weathered,very weak, low hardness to moderately hard, intensely fractured
SILTY CLAY (CL/OL) [Native Soil]Stiff to very stiff, moist, bluish gray to gray, organic to semi-organic,trace sand
CLAYEY SAND (SC) [Native Soil]Medium dense, very moist, bluish gray to gray, fine- to medium-grainedsand
HD: 20%<5 microns
CLAYEY SAND / SANDY CLAY WITH GRAVEL (SC/CL), medium dense /stiff, moist, very dark gray and black, faintly mottled, organic tosemi-organic, ~40-45% fine- to medium-grained sand, ~40-50% lowplasticity fines, ~10-20% fine gravel (serpentinite fragments and pockets ofreddish brown chert), wood fragments, trace brick fragments to 1/8 inch dia.[Fill] (continued)
Becomes blocky and differentially weathered (completely to slightlyweathered), soft to low hardness; remains very weak, intensely fractured
4.5-ft run; RQD=0%.
5.0-ft run; RQD=0%.
Start coring with HQ corebit and barrel.
Down pressure of 140 psiduring drilling 40-45 ft.
SA: %F=33, %G=2LL=31, PI=15TX-CIU(R)
Stiffer drilling 39-40 ft;250-psi down pressureto advance hole.
SANDY CLAY WITH SILT (CL/CH) [Native Soil / Colluvium]Stiff, moist, bluish gray, medium to high plasticity
Project Number: 26814957
Project Location: Piedmont, Alameda County, California
Project: Dynamic Stability of Estates Dam
30
35
40
45
50
55
60
65
715
710
705
700
695
690
685
Re
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Figure A-5
Log of Boring VQ-40
Sheet 2 of 3
SAMPLES
Gra
phic
Log
15.114.3
14.8
12.9
Sam
plin
gR
esis
tance,
blo
ws / foot
Wa
ter
Co
nte
nt,
%
Recovery
, %
Ele
vation,
feet
Type
10A10B
Dry
Un
itW
eig
ht,
pcf
MATERIAL DESCRIPTION REMARKS ANDOTHER TESTS
Depth
,fe
et
Num
ber
MATERIAL DESCRIPTION
Recovery
, %
Gra
phic
Log
SAMPLES
Sam
plin
gR
esis
tance,
blo
ws / foot
Num
ber
Depth
,fe
et
REMARKS ANDOTHER TESTS
Dry
Un
itW
eig
ht,
pcf
Type
Ele
vation,
feet
Run 4
Run 5
4.8-ft run; RQD=0%.
2.2-ft run; RQD=32%.
End drilling at 16:00 on3/31/04.
CLAYEY SHALE [Franciscan Complex Bedrock], gray to black, completelyto highly weathered, very weak, soft to low hardness (continued)
Carbonate nodules
SANDSTONE [Franciscan Complex Bedrock]Bluish gray, locally clayey, highly to moderately weathered, weak,intensely fractured
Bottom of boring at 72.0 feet
Downhole OYO suspension logging performed in uncased holeBorehole backfilled with cement grout on 4/1/05.
100
5425°, J, MW-W, No-Cl, No-Pa, Pl, SR
Sheet 3 of 3
Log of Boring VQ-40
Figure A-5Re
po
rt:
GE
O_
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B1
A_
OA
K;
F
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OA
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ES
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/17
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Wa
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nt,
%
680
675
670
665
660
655
650
65
70
75
80
85
90
95
100
Project: Dynamic Stability of Estates Dam
Project Location: Piedmont, Alameda County, California
Project Number: 26814957
Appendix B SPT Energy Measurements
Appendix C Downhole Geophysical Surveys
Appendix D Laboratory Testing
Appendix D Laboratory Testing
X:\X_GEO\ESTATES DAM\TASK E -- ENGINEERING REPORT\FINAL REPORT\DYNAMIC STABILITY ANALYSIS_R5A.DOC\27-OCT-06\\OAK D-1
This appendix presents the results of laboratory tests completed as part of the Estates Dam
dynamic stability analysis.
The laboratory tests were conducted at the URS Pleasant Hill Laboratory. Prior to conducting the
tests, the soil and rock samples were visually inspected in the laboratory. Appropriate tests were
selected to assist in subsequent evaluation of material properties for use in the dynamic stability
analyses. The types of tests performed are listed below, along with the ASTM standard
procedure designations.
In-Situ Moisture-density (ASTM D2216, D2937)
Sieve analysis (ASTM D422)
Hydrometer analysis (ASTM D422)
Atterberg Limits (ASTM D4318)
Specific Gravity (ASTM D854)
Consolidated-undrained (CIU) triaxial strength with pore pressure measurements (ASTM
D4267).
The laboratory tests were generally conducted in accordance with the noted ASTM standards.
Consolidation pressures for the CIU tests were selected based on estimated overburden pressures
at each sample depth and location. The test results are summarized in Table D-1. Summary plots
of plasticity data are presented in Figures D-1 and D-2. Summary plots of gradation data are
presented in Figures D-3 through D-7. The detailed lab sheets for the shear strength tests are also
attached. Abbreviated test results for each sample are also included in the boring logs at the
appropriate depths.
Appendix E Site Geology
Appendix E Site Geology
X:\X_GEO\ESTATES DAM\TASK E -- ENGINEERING REPORT\FINAL REPORT\DYNAMIC STABILITY ANALYSIS_R5.DOC\3-OCT-06\\OAK E-1
John Wakabayashi, Ph.D., P.G.
Geologic Consultant 2027 E. Lester Ave, Fresno, CA 93720
johnwako@sbcglobal.net
May 25, 2005
Lelio Mejia, Ph.D., P.E.
Principal and Vice President
URS Corporation
1333 Broadway, Suite 800
Oakland, CA 94612
Dear Dr. Mejia,
The following memorandum is a description of the site geology at Estates Dam. I have
embedded the figure within the main Word file, so there is no need for a separate figure and text
file.
Please contact me if you have any questions.
Sincerely,
John Wakabayashi
P.G. No. 5890
Appendix E Site Geology
X:\X_GEO\ESTATES DAM\TASK E -- ENGINEERING REPORT\FINAL REPORT\DYNAMIC STABILITY ANALYSIS_R5.DOC\3-OCT-06\\OAK E-2
SITE GEOLOGY, ESTATES DAM
DRAFT FINAL
General
Estates Dam was constructed across a gully near a ridgetop in Piedmont, California. The rock
at the damsite and surrounding the reservoir appears to be blueschist-facies metagraywacke of
the Franciscan Complex. There is some uncertainty in the location of contacts between bedrock
units at the dam and reservoir, because only two limited exposures of rock were found during the
field reconnaissance and it was not clear whether those two exposures were actually in-place
bedrock. This issue will be discussed further in the next section. The site of the dam and
reservoir is surrounded by residential neighborhoods that have existed for decades. Bedrock
exposures are scarce in this area, and many exposures are on private residential land. Residential
development, including the cutting, grading, and filling associated with construction of homes
and roads, has significantly altered the land surface, masking the natural geomorphology and
distribution of surficial deposits that existed before.
The Hayward Fault is located about 430 meters (1400 feet) northeast of Estates Dam
(Lienkaemper, 1992) (Fig. 1). The Hayward Fault in this area strikes subparallel to the Warren
Freeway and is located slightly east of the freeway. This fault marks the contact between
Franciscan Complex bedrock units to the west and Coast Range ophiolite, Great Valley Group
with minor Franciscan Complex rocks to the east. Several different Franciscan Complex rock
units crop out west of the Hayward fault and the strikes of their bedding, as well as the strikes of
the bounding contacts, are slightly more westerly (by about 15 to 20 degrees) than that of the
Hayward fault. This bedrock structural grain and resultant erosional contrasts may have
influenced the general shape of the hills in this area because the ridgecrests trends have a similar
orientation. The Franciscan rock units west of the Hayward fault, including those in the vicinity
of the Estates Dam and Reservoir have a northeasterly dip.
Because of the modification of the land surface by development, assessment of
geomorphology related to active faulting is difficult. The Franciscan bedrock of the site contains
a number of small shears (EBMUD 1939; Shannon and Wilson, 1965b; Wahler and Associates,
1980), as is typical for these rocks. Most such structures formed over 80 million years ago, but
there is no difference in physical appearance between old faults and active ones because both
types of faults would have formed under brittle conditions. There are no stratigraphic overlap
relationships or intrusive relationships to constrain the age of faults or shears in the dam site
area. Examination of 1939 vintage air photos that predated most, but not all, of the development
in the area does not reveal any geomorphic features indicative of active faulting passing through
the dam or reservoir site.
The site geology is shown on Figure 1. The Franciscan bedrock units in the vicinity of the
dam site will be described below, followed by a discussion of faulting at the dam site and slope
stability in the area.
Franciscan Complex: Blueschist-facies metamorphic unit (KJfm on Fig. 1).
Most of this rock unit consists of weakly foliated blueschist-facies metagraywacke but
bluish, schistose or phyllitic, metavolcanic rocks also are present; such rocks are commonly
referred to as “blueschists”. None of the latter were found in the vicinity of the reservoir or dam.
The metagraywacke appears to underlie the reservoir based on two outcrops observed in a field
reconnaissance done on February 3, 2005. One apparent outcrop is located along the cutslope
northwest of the reservoir, and the other outcrop was found beneath ivy that covers the cutslope
Appendix E Site Geology
X:\X_GEO\ESTATES DAM\TASK E -- ENGINEERING REPORT\FINAL REPORT\DYNAMIC STABILITY ANALYSIS_R5.DOC\3-OCT-06\\OAK E-3
south of the southeast corner of the reservoir. The rocks comprising these two outcrops consist of
weakly foliated metagraywacke. The interpretation that this rock type underlies the reservoir is
dependent on these two outcrops being in place. Based on previous reports these small outcrops
appear to represent the underlying bedrock, but there are two reasons for skepticism about these
rocks: (1) the outcrops are small (less than a meter across), and (2) they occur significantly west
of the western margin of this unit originally mapped by Wakabayashi (1984; note, however, that
this mapping excluded rocks within the reservoir grounds). Earlier investigations (EBMUD
1939; Shannon and Wilson, 1965; Wahler Associates, 1980) had access to drill core samples or
excavation exposures, but they described the rock as Franciscan sandstone, a description that
would apply to the metagraywacke unit and the unfoliated graywacke unit to the west. If the two
exposures of rock found on the perimeter of the reservoir are not in-place bedrock, then it is
possible that the sandstone unit underlying the reservoir and the dam axis is the unfoliated
sandstone of the Alcatraz terrane (see next section) instead of the foliated unit because this unit is
thicker (broader in map view) both north and south of the reservoir area (Fig. 1). The following
discussions of site geology will assume that the two outcrops observed along the perimeter of the
reservoir are in place. One consequence of the two reservoir perimeter outcrops being
metagraywacke is that it significantly changes the local bedrock distribution noted by
Wakabayashi (1984) and reviewed in Wakabayashi (2005). In particular, the basis for the
northeast-striking bedrock cross fault noted in the discussion of Wakabayashi (2005) would not
exist.
The weakly foliated metagraywacke found in the reservoir vicinity is part of a belt, up to 400
meters (1300 feet) wide of similar rocks that extends northwest of Lake Temescal, an along-
strike length of about 5 km (3 mi.); another belt of identical rocks crops out north of Berkeley,
and these rocks have collectively been called the Angel Island nappe (Wakabayashi, 1992). The
rock does not have a strong tendency to break along the foliation planes, probably because the
foliation is comparatively weakly developed. Consequently the pattern of fracture in outcrops
differs little from the unfoliated sandstone unit that structurally underlies it. Moreover, the
metagraywacke and unfoliated sandstones weather to the same light tan color in surface
outcrops, making the two units difficult to distinguish without closer inspection of freshly broken
surfaces. The metagraywacke is hard and strong when fresh and ranges from little to intensely
fractured.
Petrographic analysis shows the foliated metagraywacke to contain typical blueschist facies
metamorphic minerals such as jadeite, lawsonite, and glaucophane in addition to common
sandstone constituents such as quartz, albite, white mica, and chlorite, (Wakabayashi, 1992;
1999a). No fossil or isotopic age data are available on this unit in this area, but Wakabayashi
(1992) correlated this unit to similar rocks on Angel Island that have yielded early Cretaceous
fossils. An early to mid Cretaceous metamorphic age has been estimated for this unit by means
of correlation to isotopically dated units of similar structural setting and lithology (Wakabayashi,
1992; 1999b).
In the reservoir area, the rocks strike northwesterly and dip northeast, similar to other
Franciscan units in the area. The western boundary of this unit apparently passes just east of the
axis of the dam, as constrained by the surface outcrops and by four boreholes, including two on
the dam axis, that encountered Alcatraz terrane sandstone and sheared shale (Fig. 1). There is a
profound difference in metamorphic grade between the metagraywacke unit and the unfoliated,
prehnite-pumpellyite facies, graywacke unit to the west. The difference in metamorphic grade
indicates that the contact between the two units must be a fault. Although there is no exposure of
Appendix E Site Geology
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the fault zone anywhere in the reservoir vicinity, a correlative contact between identical jadeite-
bearing metagraywacke on the east and prehnite-pumpellyite facies graywacke on the west is
exposed in El Cerrito in an inactive quarry (Wakabayashi, 1999a). Here the contact is marked by
a shale matrix mélange zone (shear zone) that is 20 to 30 meters (60-100 feet) thick. Based on
observations at this exposure the shear zone matrix is somewhat stronger than typical mélange
matrix because it has undergone some recrystalization. However, it is still moderately to
intensely fractured and, at best, moderately strong. Blocks observed in this shear zone at El
Cerrito are mostly unfoliated graywacke that is hard and strong and little to intensely fractured.
Such blocks appear to range up to at least 6 m (20 ft) in long dimension. Smaller blocks of hard
and strong basalt and chert are also found at the El Cerrito locality. The maximum dimension of
such blocks observed is about 3 m (10 feet).
Franciscan Complex: Alcatraz Terrane (Kfa on Fig. 1)
This unit consists of unfoliated sandstones and shales and it forms a belt parallel to and west
of the foliated metagraywacke (Fig. 1). These rocks crop out in a belt up to 500 m (1600 feet)
wide and it extends northwest of Lake Temescal, giving the belt a length of about 5 km (3 mi.)
along strike and it also forms a separate belt of outcrops in El Cerrito. This unit strikes northwest
and dips northeast, placing it structurally beneath the metamorphic unit. The sandstones
petrographically resemble Alcatraz terrane rocks found in San Francisco and the unit occupies
the same structural position within the Franciscan Complex in general, so they have been
assigned to the Alcatraz terrane (Wakabayashi, 1992), which has a mid Cretaceous depositional
age (Elder and Miller 1993). This unit ranges from well bedded to a "broken formation". The
broken formation is essentially a unit consisting of some preserved sandstone and shale bedding
but locally exhibiting block-in-matrix structure of sheared shale (matrix) and sandstone blocks.
This broken formation texture is apparent in bedrock samples taken from the four new borings
completed on and slightly downstream of the dam axis (locations shown on Fig. 1). This belt of
rocks apparently narrows considerably in the vicinity of Estates Dam (Fig. 1) and passes west of
the reservoir. The sandstones of this unit are hard and strong when fresh and range from little to
intensely fractured. The sheared shale is soft and weak.
Franciscan Complex: Mélange including Marin Headlands Terrane rocks (KJfmh on Fig. 1)
This unit consists of a shale matrix, seldom exposed, with blocks of unfoliated sandstone
(graywacke), chert, basalt (commonly called “greenstone”), and serpentinite. The chert and
basalt are correlative to the Marin Headlands Terrane of Jurassic to mid Cretaceous age
(Wakabayashi, 1992). The matrix foliation and bedding of included blocks strikes northwest and
dip northeast, so the unit structurally underlies the Alcatraz terrane. Because the adjacent
sandstone units both east and structurally above(Alcatraz terrane) and west and structurally
below (Novato Quarry) consist of vastly different rocks of different origins, the bounding
contacts of this mélange unit are considered faults; indeed the entire unit can be considered an
ancient fault zone (Wakabayashi, 1992). Because the sheared matrix forms few exposures, the
presence of this unit is mapped primarily on the basis of chert and basalt (Fig. 1). The presence
of a large chert outcrop about 150 m (500 ft) south of the reservoir suggests that the eastern
border of this unit passes close (likely less than 50 m) to the downstream toe of the dam (Fig. 1).
This unit has widely varying physical characteristics. The matrix is generally friable and weak
and intensely fractured to crushed, and weathering commonly alters the sheared shale to clay.
When fresh, the sandstone blocks are commonly hard and strong to very strong and little to
Appendix E Site Geology
X:\X_GEO\ESTATES DAM\TASK E -- ENGINEERING REPORT\FINAL REPORT\DYNAMIC STABILITY ANALYSIS_R5.DOC\3-OCT-06\\OAK E-5
intensely fractured. Fresh basalt blocks are generally hard and strong to very strong and massive
to intensely fractured. Chert blocks are very hard and strong to very strong, and closely to
intensely fractured, except for some recrystallized blocks that exhibit much wider fracture
spacing.
Franciscan Complex: Novato Quarry Terrane (Knq on Fig. 1)
This is the westernmost belt of Franciscan rocks in the area and it consists of sandstones and
shales that contain a significant amount of potassium feldspar. This unit was deposited in the late
Cretaceous (Blake et al., 1984). It is the most extensive Franciscan rock unit in this part of the
East Bay and it forms a belt of rocks that strikes northwest, dips northeast and includes Albany
Hill and the exposures at Rockridge quarry. These rocks are commonly hard, strong, and little to
intensely fractured.
Franciscan Complex: undifferentiated mélange (Kjfmel on Fig. 1)
This unit crops out directly west of the Hayward fault in the vicinity of Park Avenue (the
major freeway interchange southeast of the reservoir site in Fig. 1). Limited exposures suggest
that this unit consists of a sheared shale matrix with blocks that include serpentinite, the
Franciscan metamorphic unit (KJfm) described above, and a variety of other rock types. On the
basis of the included units and the local field relations, this unit probably formed in the
Cretaceous. As with the mélange unit KJfmh described above, the physical properties of the
rocks vary. The matrix is weak, but some of the blocks may be very hard and strong. The
location of the western contact of this unit is poorly constrained owing to scarcity of outcrops,
particularly the northern part of this contact. It is possible that this unit extends north and
underlies most of the area of subdued topography northwest of the Warren Freeway-Park
Avenue interchange and south of the end of the steep east-facing slope above Warren Freeway.
Dam fill and possible underlying native soil
The dam is composed primarily of heterogenous fill, that is mixed in color and physical
character. Based on the lithology of the gravel, this fill appears to be derived from Franciscan
source material similar to that present in the reservoir area. In the four borings drilled through the
dam (VQ-37, 38, 39, 40; locations shown but not numbered on Fig. 1), a fine-grained unit, poor
in gravel, fairly rich in organics, and of uniform color and texture, was encountered directly
above bedrock. This unit was 10, 13, 7, and 6 feet thick in borings VQ-37, 38, 39, and 40,
respectively. It is difficult to determine, on appearance alone, whether or not this unit is fill or
native soil. In one boring, VQ-38, this unit appears to be fill based on an abrupt contact with
underlying weathered bedrock that has a very different color. In other borings, the contact
relations with underlying bedrock were not directly observed, so the origin of the unit in those
borings is less certain. However, because this unit in VQ-37, 39, and 40, appears remarkably
similar to the unit that appears to be fill in VQ-38, it is most likely that this unit is fill.
Faulting in dam site vicinity
The Hayward fault passes about 430 m (1400 ft.) northeast of the dam and is the only fault
with demonstrated Holocene activity that has been mapped near the reservoir or dam (Fig. 1).
The Franciscan rock units are bordered by faults and contain many minor faults and shears, as a
consequence of subduction-related deformation that took place (for the units in the dam site area)
in the Cretaceous (Wakabayashi, 1992; 1999b). There is no positive evidence for Holocene
Appendix E Site Geology
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reactivation of any of these features, either as independent faults or as structures that exhibit
coseismic movement with earthquakes on the Hayward fault. However, geomorphic evidence
that would normally be used to assess potential activity of structures in this area has been
obscured or erased by development. There are no stratigraphic overlap relationships or intrusive
relationships to constrain the age of faults or shears in the dam site area. The earliest set of air
photos we examined was taken in 1939, a time that predated most, but not all, of the
development in the reservoir vicinity. No lineaments or other geomorphic features that might be
associated with active fault movement were noted in the dam vicinity, except for the Hayward
fault as delimited by Lienkaemper (1992). Given the distance between the dam site and the
Hayward fault, it is likely that any hypothetical active features passing through the dam site
would not be independent faults, but rather ones that move sympathetically with earthquakes on
the Hayward fault (the last major earthquake on which occurred in 1868). No evidence for 1868
surface deformation in the reservoir or dam area was noted in the various reports of the 1868
earthquake features reviewed by Lienkaemper (1992). The lack of surface geomorphology
indicative of active fault movement in 1939 air photos and the lack of documentation of features
related to surface displacement in 1868 suggest that the possibility of active fault movement
through either the dam or reservoir is highly unlikely.
Slope Movement
Air photos also were examined for evidence of slope movement. This is important because
large slides involving Franciscan rocks cover large portions of the East Bay hills north of
Berkeley (mostly in the El Cerrito and Richmond Hills). In contrast, neither the 1939 air photos
nor surface mapping show significant landslide features in the reservoir and dam vicinity. A
major difference between this area and the region north of Berkeley is that the Franciscan
bedrock in the latter area includes a much higher proportion of mélange (Wakabayashi 1984), the
matrix of which is particularly prone to sliding. Air photos appear to show geomorphic features
suggestive of either small slides or talus aprons at the base of the steep slope north and east of
the reservoir and above Warren Freeway. A geomorphic feature of potential significance is an
area of somewhat subdued topography that occurs southeast of the reservoir at the southern end
of the steep east-facing slope above Warren Freeway described above. This feature has a shape
that might suggest an eastward-directed, ancient landslide. The nature and distribution of
bedrock outcrops cannot be used to rule out the possibility of an old slide mass in this area
because no rock outcrops were found there, but there are at least two alternative explanations for
the geomorphology in this area: (1) The area is underlain by the shale matrix melange unit
Kjfmel as shown in Fig. 1 that cannot hold as steep slopes as the metagraywacke unit that forms
the steep east-facing slope to the north. (2) The topography in the area is influenced by a right
step along the Hayward fault. The second alternative is consistent with the width of the right
(releasing, or transtensional) step observed along the Hayward fault in the vicinity of the Park
Avenue-Warren Freeway interchange (Fig. 1) (Lienkaemper, 1992), but suggests that an active
strand of the Hayward fault continues northwestward approximately marking the western
boundary of the area of subdued topography. There is no geomorphology suggestive of an active
fault trace in this area in the 1939 air photos, nor did Lienkaemper (1992) identify such a feature,
either by direct examination or reviews of previous research. Consequently this second
alternative is not considered a likely one. The first alternative is the interpretation shown on the
map in Figure 1. That interpretation does not entirely rule out the possibility of a landslide in that
area, given that the mélange unit is likely susceptible to sliding. However, if the area of subdued
Appendix E Site Geology
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topography is underlain by the mélange unit, it is a different bedrock type than that which
underlies the dam and reservoir site.
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Francisco Bay Region: in Blake, M. C., Jr., ed., Franciscan Geology of Northern California:
Pacific Section Society of Economic Paleontologists and Mineralogists, v. 43, p. 5-22.
Elder, W.P., and Miller, J.W., 1993, Map and checklist of Jurassic and Cretaceous macrofossil
localities within the San Jose 1: 100,000 quadrangle, California, and discussion of
paleontological results: U.S. Geological Survey Open File Report 93-503.
EBMUD, 1939, Feature report No. 28 Report on reconstruction of Piedmont No.1 Reservoir:
Internal EBMUD report dated September 1, 1939 (contains figures dated as late as November
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Lienkaemper, J.J., 1992, Map of recently active traces of the Hayward fault, Alameda and Contra
Costa Counties, California: U.S. Geological Survey Miscellaneous Field Studies Map MF-
2196.Wagner, D.L., Bortugno, E.J., and McJunkin, R.D., 1990, Geologic map of the San
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Shannon and Wilson, 1965, East Bay Municipal Utility District Piedmont No. 1 Reservoir
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25, 1965.
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dated June 1980.
Wakabayashi, J., 1984 (unpublished geologic mapping), Geologic mapping of Franciscan
Complex, Coast Range ophiolite, and related rocks, Richmond to Hayward.
Wakabayashi, J., 1992, Nappes, tectonics of oblique plate convergence, and metamorphic
evolution related to 140 million years of continuous subduction, Franciscan Complex,
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Wakabayashi, J., 1999a, The Franciscan Complex, San Francisco Bay area: A record of
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Wakabayashi, J., 1999b, Subduction and the rock record: Concepts developed in the Franciscan
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Wakabayashi, 2005, Review of existing data on site geology, Estates Dam: draft memorandum
prepared for URS Corp., dated January 6, 2005.
Appendix E Site Geology
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