HomeMy WebLinkAboutCT 15-05; UPDATE GEOTECHNICAL INVESTIGATION; 2015-02-24ENT
UPDATE
GEOTECHNICAL INVESTIGATION
QUARRY CREEK
CARLSBADIOCEANSIDE, CALIFORNIA
PREPARED FOR
CORNERSTONE COMMUNITIES
SAN DIEGO, CALIFORNIA
FEBRUARY 24, 2015
PROJECT NO. 07135-42-05(4
GEOCON
INCO R PORAT E D
GEOTECHNCAL ENVRONMEN1At MATERIAL.S
Project No. 07135-42-05
February 24, 2015
Cornerstone Communities
4365 Executive Drive, Suite 600
San Diego, California 92121
Attention: Mr. Jack Robson
Subject: UPDATE GEOTECHNICAL INVESTIGATION
QUARRY CREEK
CARLSBAD/OCEANSIDE, CALIFORNIA
Dear Mr. Robson:
In accordance with your authorization, we are pleased to submit the results of our update
geotechnical investigation for the proposed Quarry Creek project. Conclusions and recommendations
presented herein are based on review of available published geotechnical reports and literature,
observations during previous grading performed on the property for reclamation, previous subsurface
geotechnical exploration and site reconnaissance of existing conditions.
The eastern half of the property has been used for mining and crushing rock to produce commercial
aggregates. As the result, the eastern half of the site is underlain by compacted fill, previously placed
fill, undocumented fill, sedimentary, volcanic, and intrusive bedrock. Reclamation grading has
occurred on this portion of the site. The western half of the site is in an ungraded natural condition.
The accompanying report presents findings from our studies relative to geotechnical engineering
aspects of developing the property. The site is considered suitable for the proposed improvements
provided the recommendations of this report are followed.
Should you have questions regarding this report, or if we may be of further service, please contact
the undersigned at your convenience.
Very truly yours,
GEOCON INCORPORATED
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SADR EG1778 No. 1778 CL CERTIFIED
ENGINEERING AS:RCM:dmc GEOLOGIST
(4/del) Addressee opc
(2/del) The Corky McMillin Companies
Attention: Mr. Don Mitchell
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TABLE OF CONTENTS
PURPOSE AND SCOPE......................................................................................................................1
PREVIOUS SITE USAGE AND GRADING.......................................................................................2
SITE AND PROJECT DESCRIPTION ................................................................................................ 3
SOIL AND GEOLOGIC CONDITIONS..............................................................................................3
4.1 Compacted Fill (Qcf) .................................................................................................................. 4
4.2 Undocumented Fill (QudO .........................................................................................................4
4.3 Previously Placed Compacted Fill (Qpcf)..................................................................................4
4.4 Previously Placed Fill (Qpf).......................................................................................................5
4.5 Topsoil (Unmapped)...................................................................................................................5
4.6 Surficial Landslide Debris (Qlsf) ...............................................................................................5
4.7 Alluvium (Qal) ...........................................................................................................................5
4.8 Colluvium (Qc) ...................................................................... ..................................................... 6
4.9 Terrace Deposits (Qt).................................................................................................................6
4.10 Santiago Formation (Ts).............................................................................................................6
4.11 Salto Intrusive (Jspi)...................................................................................................................7
GROUNDWATER................................................................................................................................7
GEOLOGIC HAZARDS.......................................................................................................................7
6.1 Faulting and Seismicity..............................................................................................................7
6.2 Liquefaction ................................................................................................................................ 9
6.3 Flow Slide Potential .................................................................................................................10
6.4 Landslides.................................................................................................................................10
CONCLUSIONS AND RECOMMENDATIONS..............................................................................11
7.1 General .....................................................................................................................................11
7.2 Excavation and Soil Characteristics.........................................................................................11
7.3 Subdrains..................................................................................................................................12
7.4 Grading.....................................................................................................................................13
7.5 Surcharge Fill ...........................................................................................................................16
7.6 Settlement Monitoring..............................................................................................................16
7.7 Slope Stability ..........................................................................................................................16
7.8 Seismic Design Criteria .................................................................................. .......................... 18
7.9 Foundation and Concrete Slab-On-Grade Recommendations..................................................19
7.10 Retaining Wall Recommendations ................................................................. .......................... 24
7.11 Detention Basin and Bioswale Recommendations...................................................................26
7.12 Site Drainage and Moisture Protection ....................................................................................27
LIMITATIONS AND UNIFORMITY OF CONDITIONS
TABLE OF CONTENTS (Concluded)
MAPS AND ILLUSTRATIONS
Figure 1, Vicinity Map
Figure 2 and 3, Geologic Map
Figure 4, Geologic Cross Sections AA' through DD'
Figure 5, Typical Canyon Subdrain Detail
Figure 6, Typical Subdrain Cut-Off Wall Detail
Figure 7, Typical Subdrain Outlet Headwall Detail
Figure 8, Construction Detail for Lateral Extent of Removal
Figure 9, Settlement Monument
Figures 10— 14, Slope Stability Analysis
Figure 15, Typical buttress Fill Detail
Figure 16, Typical Retaining Wall Drain Detail
APPENDIX A
FIELD INVESTIGATION
Figures A-i - A-5, Logs of Large Diameter Borings
Figures A-6 - A-27, Logs of Trenches
Figures A-28 - A-33, Logs of Small Diameter Borings
Figures A-34 - A-39, Logs of Trenches (Geocon 9-10-09)
APPENDIX B
LABORATORY TESTING
Table B-I, Summary of Laboratory Maximum Dry Density and Optimum Moisture Content
Table B-IT, Summary of Laboratory Direct Shear Test Results
Table B-Ill, Summary of Laboratory Expansion Index Test Results
Table B-IV, Summary of Laboratory Expansion Index Test Results
Performed During Reclamation Grading
Table B-V, Summary of Laboratory Water-Soluble Sulfate Test Results
Table B-VT, Summary of Laboratory Water-Soluble Sulfate Test Results
Performed During Reclamation Grading
APPENDIX C
SLOPE STABILITY ANALYSIS
Table C-I, Summary of Soil Properties used for Slope Stability Analyses
Table C-TI, Summary of Slope Stability Analyses
Figure C-i, Cut Slope
Figures C-2 - C-3, Buttress Fill Slope
APPENDIX D
FLOW ANALYSIS
Figure D- 1, Stability Analysis for Flow Slide Potential
Figure D-2, Stability Analysis to Determine Yield Coefficient
APPENDIX E
RECOMMENDED GRADING SPECIFICATIONS
LIST OF REFERENCES
UPDATE GEOTECHNICAL INVESTIGATION
1. PURPOSE AND SCOPE
This report presents the results of an update geotechnical investigation for the proposed Quarry
Creek development. The purpose of the geotechnical investigation is to evaluate surface and
subsurface soil conditions and general site geology, and to identify geotechnical constraints that may
impact development of the property. In addition, the purpose of this report is to provide foundation
design criteria, concrete flatwork recommendations, retaining wall recommendations, excavation and
remedial grading considerations that can be utilized in developing project budgets. The scope of this
investigation also included a review of readily available published and unpu'Dlished geologic
literature, aerial photographs and the following documents previously prepared for the property:
Preliminary Geotechnical Investigation, Quarry Creek II, Carlsbad/Oceanside, California,
prepared by Geocon Incorporated, dated February 24, 2015 (Project No. 07135-42-03).
Foundation Report, Quarry Creek Bridge, Carlsbad, California, prepared by Geocon
Incorporated, dated August 21, 2014 (Project No. 07135-42-04A).
Mass Grading Plans for Quarry Creek, prepared by Project Design Consultants, undated.
Final Report of Testing and Observation Services During Site Grading, Quarry Creek,
Carlsbad, California, prepared by Geocon Incorporated, dated April 4, 2013 (Project
No. 07135-42-02).
Final Report of Testing and Observation Services During Site Grading, Quarry Creek,
Oceanside, California, prepared by Geocon Incorporated, dated March 11, 2013 (Project
No. 07135-42-02).
Update Geotechnical Investigation, Amended Reclamation Plan, Quarry Creek Refined
Alternative 3, Carlsbad, California, prepared by Geocon Incorporated, dated September 10,
2009 (Project No. 07135-42-01).
Limited Geotechnical Investigation to Evaluate Hardrock Constraints fcr Quarry Creek,
Carlsbad, California, prepared by Geocon Incorporated, dated April 9, 2004 (Project
No. 07135-42-01B.
EIR - Level Soil and Geologic Reconnaissance Quarry Creek II Carlsbad/Oceanside,
California, prepared by Geocon Incorporated, dated October 20, 2011(Project No. 07135-
42-0IB).
The site is located south of State Route 78 and west of College Boulevard in Carlsbad, California
(see Vicinity Map, Figure 1).
The eastern portion of the site has been graded as part of the reclamation process. Geocon
Incorporated performed compaction testing and observation services during the grading operations.
Project No. 07135-42-05 - 1 - - February 24, 2015