cemex eliot quarry lake a evaluation report alameda county...

CEMEX Eliot Quarry

Lake A Evaluation Report

Alameda County, California

May 7, 2015

CEMEX Eliot Quarry



May 7, 2015

Project No. GT13-16

Prepared for:

CEMEX5180 Golden Foothills, ParkwayEl Dorado Hills, California 95762

7400 Shoreline Drive, Ste. 6 Stockton, California 95219 Tel: 209-472-1822 Fax: 209-472-0802 www.kanegeotech.com

http://www.kanegeotech.com

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TABLE OF CONTENTS

TABLE OF CONTENTS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . iii

1. INTRODUCTION.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.1 General.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.2 Purpose. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

2. SLOPE STABILITY ANALYSES. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22.1 Lake A Slope Stability Analyses. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22.2 Geologic Model.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

2.2.1. Lake A, Profile A.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32.2.2. Lake A, Profile B.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32.2.3. Lake A, Profile C.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32.2.4. Lake A, Profile D.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

2.3 Lake A Slope Stability Results. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

3. CONCLUSIONS AND RECOMMENDATIONS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

4. REFERENCE. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

5. LIMITATIONS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

APPENDIX ASlope Stability Analysis Profile A.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

Static Analysis. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9Seismic Analysis.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

APPENDIX BSlope Stability Analysis Profile B.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

Static Analysis. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25Seismic Analysis.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

APPENDIX CSlope Stability Analysis Profile C. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39


APPENDIX DSlope Stability Analysis Profile D. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57


APPENDIX ESlope Stability Analysis Profile D (After Grading). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77

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Figure 1. Overview of Chain of Lakes

7400 Shoreline Drive,Stockton, California 95219

Suite 6209-472-1822 Phone 209-472-0802 Fax

[email protected]

1441 Kapiolani BoulevardSuite 1115

Honolulu, Hawaii 96814808-356-2668

www.kanegeotech.com

CEMEX Eliot Quarry



1. INTRODUCTION1.1 GeneralKANE GeoTech, Inc. (KANE GeoTech) was contracted by CEMEX, Inc. (CEMEX) to assess theslope stability of Lake A located in Livermore, California in Alameda County. Lake A is presentlyan inactive quarry that will eventually be the first link in the Chain of Lakes proposed by AlamedaCounty Flood Control and Water Conservation District, Zone 7, Figure 1. The slope stabilityanalysis of Lake A has been prepared to support the Reclamation Plan Amendment that CEMEXhas submitted to Alameda County. Additional mining will not occur within Lake A. However, thereclamation of Lake A for use in the Chain of Lakes will include limited additional excavation insome areas and filling or grading of other areas. The geologic model, material properties, andseismic coefficients used in this evaluation report for Lake A are based on the information andinterpretations presented in the accompanying Geotechnical Characterization Report and its

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mailto:[email protected]

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CEMEX Eliot QuarryLake A Evaluation ReportAlameda County, CaliforniaPage 2

Figure 2. Overview of Lake A cross section profiles

supporting Appendices, which contain additional site background and information. Summariesof pertinent references and complete methodologies for analyses can also be found in theGeotechnical Characterization Report.

1.2 PurposeThe purpose of this report is to describe the results of the slope stability analyses, for Lake A, performed as part of the permitting requirements for Eliot Quarry.

2. SLOPE STABILITY ANALYSES2.1 Lake A Slope Stability AnalysesA total of four profiles were constructed and analyzed, Profiles A-D, Figure 2. Worst casescenarios were modeled, with the pit being completely empty and the slopes fully saturated withgroundwater. For the seismic analyses, a seismic coefficient of 0.21 was used, as described inSection 4.5 of the Geotechnical Characterization Report. This coefficient value is consideredquite conservative, or protective of surrounding properties, as discussed in more detail in theGeotechnical Characterization Report. Material properties are given in Table 1.

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CEMEX Eliot QuarryLake A Evaluation Report

Alameda County, CaliforniaPage 3

Profile MaterialParameters

Avg. UnitWeight (pcf)

Saturated UnitWeight (pcf)

Cohesion(psf)

Friction Angle(Deg)

A, B, C, D Clayey Gravel 134 139 200 45

A, B, C, D Low PlasticityClay

125 130 1400 24

B, C Low Plasticity Silt 116 121 1000 31

A, B, C, D High PlasticityClay

122 127 1600 7

B Well GradedSand

128 133 0 34

B Pea Gravel Fill 114 129 0 37

A, D Sheared Clay,high plasticity

122 127 1600 7

TABLE 1: TYPICAL MATERIAL PARAMETERS USED IN THE ANALYSES

2.2 Geologic ModelFollowing a review of available materials and a geotechnical investigation, a geologic model wasconstructed by KANE GeoTech. This geologic model shows the Livermore Valley’s depositionalenvironment being an alluvial system rather than the lacustrine deposit as proposed by CSA. Thedifference is an alluvial environment would result in discontinuous layers and a lacustrineenvironment has laterally continuous layers. KANE GeoTech conservatively modeled areas withcontinuous layers where drilling logs were unable to show otherwise to reflect CSA’s geologicmodel. Borings locations are shown in the Geotechnical Characterization Appendix document.Material parameters for each profile are found in Table 1.

2.2.1. Lake A, Profile A.Data from three borelogs were used in the construction of Profile A. These borelogs show thediscontinuity of the layers on the northern area of Profile A.

2.2.2. Lake A, Profile B. Data from five borelogs were used in the construction of Profile B. These borelogs also showlayers of discontinuity throughout the Profile area.

2.2.3. Lake A, Profile C.Data from two borelogs were used in the construction of Profile C. These borelogs also reflectdiscontinuous layers in the northern area of the Profile. Due to the lack of data in the center of theLake A in this area, the discontinuous layers were conservatively modeled to continue half waybetween the borelogs.

2.2.4. Lake A, Profile D.Data from three borelogs were used in the construction of Profile D. These borelogs showdiscontinuity in the northern area as well. Due to the lack of data in the center of Lake A, the low

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Lake A Profile A - Filled with Water

Circular FailureSE Slope

Circular FailureNW Slope

Block Failure SESlope

Block Failure NWSlope

FOS (Static) 2.31 2.16 2.41 2.47

FOS (Seismic) 1.25 1.20 1.30 1.30

Lake A Profile B -Filled with Water





FOS (Static) 2.01 2.38 2.76 2.32

FOS (Seismic) 1.37 1.09 1.23 1.06

Lake A Profile C - Filled with Water





FOS (Static) 2.10 2.60 3.09 1.83

FOS (Seismic) 1.19 1.52 1.04 1.53

Lake A Profile D - Filled with Water (as is)





FOS (Static) 2.76 3.15 4.23 3.04

FOS (Seismic)* 1.49 1.40 0.98 1.02 1.31

*See text, Section 2.3

TABLE 2. SLOPE STABILITY ANALYSES RESULTS

plasticity clay layers were conservatively modeled as continuous layers with a change in elevation,although, it is most likely the elevation change is due to the layers being discontinuous.

2.3 Lake A Slope Stability ResultsThe analyzed profiles and results of the static and seismic slope stability analyses for Lake A canbe found in Figure 2, Table 2, and Appendix A. Four profiles throughout Lake A were modeledand analyzed statically and seismically at various mining elevations with a 2H:1V slope gradient.Subsequent to the initiation of this investigation, CEMEX determined that Lake A will no longer be mined to the originally proposed elevations. Analyses showed that the slopes in Lake A arestable under static conditions. Profiles A, B, and C, Appendix A, are stable in both static andseismic conditions. The analyses of Profile D indicated that the slopes were stable under staticconditions, but when modeled under seismic conditions the resulting safety factor of 0.98 did notmeet the required value of 1.0 at the proposed pit depth, Appendix D; however under the revisedgrading plan the safety factor increased to 1.02, Appendix E. The slope was re-analyzed with a

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new, proposed grading profile which modeled the slope as stable under seismic conditions. Thegrading profile can also be found in Appendix E.

Profile A, located on the west slope adjacent to Isabel Avenue, was analyzed and modeled witha pit elevation of 360-ft MSL. This slope is the proposed location of the conveyance pipe that willlink Lake A to the planned chain of lakes. The slope met the required safety factors and isconsidered stable when excavated to 360-ft MSL.

3. CONCLUSIONS AND RECOMMENDATIONSAfter performing the static and seismic slope stability analyses for Lake A, our conclusions areas follows:

1. It has been determined that Lake A will no longer be mined. The slopes weremodeled under currently existing configurations, and all were stable statically andseismically with the exception of Profile D under seismic conditions. This slope was re-analyzed with a new grading plan and modeled stable under seismic conditions. Theslope where the proposed conveyance pipe is located was modeled at the conveyancepipe elevation 360-ft MSL and was stable statically and seismically.

2. Elastic rebound of the slopes after mining should be expected. It should be noted

that CSA (2009) stated that elastic rebound of Lake A slopes had occurred due tostress relief. Modeling conducted for this study shows that all slopes are stable,including those adjacent to the corrective action area (i.e. pea gravel buttress).

3. The sheared clay layer found in Lake A boreholes is not continuous. CSA’sgeologic model showed that the weak sheared clay layer is continuous. However basedon observations made from KANE GeoTech’s 2013 borelogs the sheared clay layer isnot ubiquitous at Lake A.

4. REFERENCECotton, Shires, & Associates, Inc. (2009). “As-Built Report and Summary of Construction Inspection and Testing,

Lakeside Circle Corrective Action Plan, Alameda County, California.” Report to CEMEX, Eldorado Hills, Californiaby Cotton, Shires, and Associates, Inc., Los Gatos, California, December 23, 2009.

5. LIMITATIONSThe analyses, conclusions and recommendations contained in this report are based on the siteconditions observed by KANE GeoTech and derived from the information provided. If there is asubstantial lapse of time between the submission of this report and the start of any work at thesite, or field conditions have changed due to natural causes, mining, or construction operationsat or adjacent to the site, we urge that this report be reviewed to determine the applicability of theconclusions and recommendations considering the changed conditions and time lapse. Thisreport is applicable only for the project and sites studied. After three years, KANE GeoTechshould be consulted if this report is used to make any decisions regarding the area.

KANE GeoTech, Inc.


Our professional services were performed, our findings obtained, and our recommendationsproposed in accordance with generally accepted engineering principles and practices. Thiswarranty is in lieu of all other warranties either expressed or implied. Findings and statements ofprofessional opinion do not constitute a guarantee or warranty, expressed or implied.

KANE GeoTech, Inc.

William F. Kane, PhD, PEPresidentCalifornia Registered Civil Engineer No. 55714

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APPENDIX ASlope Stability Analysis

Profile A

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Static Analysis

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Seismic Analysis

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APPENDIX BSlope Stability Analysis

Profile B

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Static Analysis

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Seismic Analysis

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APPENDIX CSlope Stability Analysis

Profile C

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Static Analysis

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Seismic Analysis

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APPENDIX DSlope Stability Analysis

Profile D

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Static Analysis

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Seismic Analysis

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APPENDIX ESlope Stability Analysis

Profile D(After Grading)

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