APPENDIX E GEOTECHNICAL INVESTIGATION REPORT

459 Pages·2011·8.29 MB·English

by  Erika Wilder

APPENDIX E
GEOTECHNICAL INVESTIGATION REPORT
APPENDIX E GEOTECHNICAL INVESTIGATION REPORT

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Page E-2 Southern California Edison
SOUTHERN CALIFORNIA EDISON
Geotechnical Investigation Report
Falcon Ridge 66kV Substation

Devore, California

May 17, 2010
Project # 10-014

TDBU
Geotechnical Engineering Group
May 17, 2010

Subject: GEOTECHNICAL INVESTIGATION REPORT
Falcon Ridge 66kV Substation
Devore, California
Project No. 10-014

Geotechnical Engineering Group TDBU has prepared this report to present the findings
of the geotechnical investigation performed for the proposed construction of the Falcon
Ridge 66kV Substation in Devore, California. The subject substation can be developed
from a geotechnical standpoint, provided the findings, conclusions, and
recommendations presented in this report are incorporated in the preparation of the final
grading plan, foundation design, and construction of the project.

The recommendations contained herein are contingent upon adequate monitoring of the
geotechnical aspects of the construction by a representative of the TDBU Geotechnical
Group.

If you should have any questions, please feel free to contact the undersigned.

_________________ _________________

Gennady Tsarev, PE Jack M. Collender, PG, CEG
Civil Engineer Senior Geologist
Phone: [phone] Phone: [phone]

_________________

Esam Abraham, PE
Senior Engineer
Cell : [phone]

TDBU – Geotechnical Engineering Group, One Innovation Way, Pomona, CA 91768
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TABLE OF CONTENTS

1.0 INTRODUCTION....................................................................................................1
2.0 PROJECT DESCRIPTION.....................................................................................1
2.1 SITE LOCATION AND DESCRIPTION ..........................................................................1
2.2 PROPOSED DEVELOPMENT.....................................................................................1
3.0 FIELD EXPLORATION & LABORATORY TESTING............................................1
3.1 FIELD EXPLORATION..............................................................................................2
3.2 GEOTECHNICAL LABORATORY TESTING ...................................................................2
4.0 GEOLOGIC SETTING ...........................................................................................2
5.0 SITE CONDITIONS................................................................................................3
5.1 GENERAL..............................................................................................................3
5.2 SUBSURFACE CONDITIONS.....................................................................................3
5.3 GROUNDWATER.....................................................................................................3
5.4 FLOODING.............................................................................................................3
5.5 GEOTECHNICAL LABORATORY TESTING RESULTS.....................................................3
6.0 FAULTING.............................................................................................................5
6.1 SEISMIC COEFFICIENTS..........................................................................................5
6.2 SITE-SPECIFIC GROUND MOTION FOR SEISMIC ANALYSIS.........................................6
6.3 SECONDARY EFFECTS OF SEISMIC ACTIVITY............................................................7
7.0 EARTHWORK/SITE GRADING RECOMMENDATIONS.......................................8
7.1 GENERAL..............................................................................................................8
7.2 OVER-EXCAVATION/REMOVAL FOR PROPOSED SUBSTATION STRUCTURES.................9
7.3 OVER-EXCAVATION/REMOVAL FOR PAVEMENT AREAS..............................................9
7.4 STRUCTURAL FILL..................................................................................................9
7.5 IMPORT FILL........................................................................................................10
7.6 SHRINKAGE AND SUBSIDENCE...............................................................................10
7.7 EXCAVATIONS AND TEMPORARY SLOPES...............................................................11
7.8 SITE DRAINAGE...................................................................................................11
8.0 DESIGN AND CONSTRUCTION RECOMMENDATIONS...................................11
8.1 GENERAL EVALUATION.........................................................................................11
8.2 FOUNDATION TYPES AND BEARING PRESSURES.....................................................11
8.3 DRILLED CAST-IN-PLACE FRICTION PILES..............................................................12
8.4 SLABS-ON-GRADE...............................................................................................13
8.5 ASPHALT CONCRETE PAVEMENT...........................................................................13
8.6 SETTLEMENT.......................................................................................................14
8.7 GEOTECHNICAL OBSERVATION..............................................................................14
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9.0 CLOSURE............................................................................................................15
10.0 REFERENCES..................................................................................................16

FIGURES

Figure 1.......................................................................................................Site Location Map
Figure 2.............................................................................Approximate Boring Location Map
Figure 3..........................................................................................Design Response Spectra

APPENDICES

Appendix A....................................................................................................Field Exploration
Appendix B..................................................................................Laboratory Testing Program
Appendix C...........................................................................Soil Corrosivity/Resistivity Study

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GEOTECHNICAL INVESTIGATION REPORT
Falcon Ridge 66kV Substation
Devore, California
May 17, 2010
Project No. 10-014

1.0 INTRODUCTION

This report presents the findings of the geotechnical investigation performed for the
proposed Falcon Ridge 66kV Substation in Devore, California. For the site location, see
Figure 1, Site Location Map.

The purposes of this investigation was to determine the nature and engineering properties
of the subsurface soils and to provide preliminary recommendations regarding general site
grading and foundation design and construction. The preliminary site plan is included as a
base for Figure No. 2, Approximate Boring Location Map.

The site earthwork and design recommendations provided in this report should be
considered preliminary. The final grading plan should be reviewed for compliance with the
design recommendations.

2.0 PROJECT DESCRIPTION

2.1 Site Location and Description

The Falcon Ridge Substation site is located on vacant land southeast of the intersection
of West Casa Grande Drive and Sierra Avenue in the City of Devore, California. The
site is a relatively flat 7.5 acre parcel at an approximate elevation of 1720 feet. The site
slopes gently to the south. Vegetation includes scattered shrubs and grasses. Access
to the site is from Summit Avenue to the south. The site is bounded by vacant land to
the north, south and west and a large warehouse to the east. Residential property is to
the northeast. Power lines run along the northwest property boundary.

2.2 Proposed Development

The proposed substation is to include a pad area for a 66 kV switchrack, a 12 kV
switchrack, transformer and capacitor bank pads and a MEER building. The pad area
measures approximately 300 feet by 300 feet. Access to the substation is from Summit
Avenue to the southeast. Grading and foundation plans for the substation have not been
provided.

3.0 FIELD EXPLORATION & LABORATORY TESTING

The scope of our investigation and the laboratory testing included a review of existing
information, site reconnaissance and a subsurface exploration for geotechnical soil
sampling and preparation of this report.

1
Falcon Ridge Substation
Site Location Map
Project Name: Falcon Ridge Substation Source: NAT GEO
Location: Devore, CA
Figure No.
TDBU Geotechnical Engineering Group
1
B-3
B-2
B-1
B-5
B-4
Approximate Boring Locations
Project Name: Falcon Ridge Substation Source: SCE drawing
Location: Devore, CA
Figure No.
TDBU Geotechnical Engineering Group
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GEOTECHNICAL INVESTIGATION REPORT
Falcon Ridge 66kV Substation
Devore, California
May 17, 2010
Project No. 10-014

3.1 Field Exploration

A total of five soil borings were drilled on March 23, 2010. These borings were completed
under the supervision of a Southern California Edison engineer. The approximate soil
boring locations are shown in Figure No. 2, Approximate Boring Location Map.

The borings (B-1 through B-5) were drilled within the project site using a truck mounted
drill rig equipped with 8-inch diameter hollow-stem augers for soil sampling. The boring
depths ranged from 9 to 26 feet below the existing ground surface (bgs). Drilling was
difficult because of the abundant boulders. Auger refusals in gravel and cobles were
encountered in most of the borings at depth between 9.0 and 18.5 feet bgs.

Relatively undisturbed thin-walled ring and bulk samples of representative subsurface
materials were obtained from the borings for laboratory testing. Standard Penetration
Tests (SPTs) were performed starting at selected intervals beginning at 7.5 feet bgs
using a standard split-barrel sampler (1.4 inches inside diameter and 2.0 inches outside
diameter).

For a description of the field exploration and sampling program, see Appendix A, Field
Exploration and Appendix B, Laboratory Testing Program.

3.2 Geotechnical Laboratory Testing

Representative samples of the site soils were tested in the laboratory to aid in the soil
classification and to evaluate relevant engineering properties of the site soils. These tests
included:

♦ In situ moisture contents and dry densities (ASTM Standard D2216)
♦ Soil corrosivity tests (Caltrans 643, 422, 417, and 532)
♦ Grain size distribution (ASTM Standard D422)
♦ Maximum dry density and optimum-moisture content relationship (ASTM
Standard D1557)
♦ Direct shear (ASTM Standard D3080)
♦ R-Value (D2844)

For in situ moisture content, see the Logs of Borings in Appendix A, Field Exploration. For
laboratory test results, see Appendix B, Laboratory Testing Program.

4.0 GEOLOGIC SETTING

The site is located in the Lytle Creek alluvial fan, approximately 2 miles south of the
mouth of Lytle Creek. The site is underlain by Quaternary alluvium which is comprised
of gravel and sand emanating from Lytle Creek (Dibblee, 2003). Boulder gravel is
common near the mountains and was encountered on-site.

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