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DESIGN LEVEL GEOTECHNICAL ENGINEERING INVESTIGATION
PROPOSED WAREHOUSE DEVELOPMENT
666 EAST DYER ROAD
SANTA ANA, CALIFORNIA
Proj ect Number: D5 6620.01
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For:
Shea Properties
130 Vantis, Suite 200
Aliso Viejo, CA 92656
December 18,201.7
www.moore twining. com
px: 559.268-7021
rx: 559.268.7126
2527 Fresno Streel
Frcsno, CA 937?l
TWININGo
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DESIGN LEVEL GEOTECHNICAL ENGINEERING INVESTIGATION
PROPOSED WAREHOUSE DEVELOPMENT
666 EAST DYER ROAD
SANTA ANA, CALIFORNIA
Project Number: D5 6620.01
For:
Shea Properties
130 Vantis, Suite 200
Aliso Viejo, CA 92656
December 18,2017
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www.rn oo retwin in g. co m
px: 559.2 68.7021
rx: 559.2 68.7126
2527 Fresno Streel
Fresno, CA 93721
TWININGo
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December 18,2017 Ds 6620.0r
Mr. Ron Revi
Shea Properties
130 Vantis, Suite 200
Aliso Viejo, California 92656
Subject:Design Level Geotechnical Engineerirg Investigation
Proposed Warehouse Development
666 East Dyer Road
Santa Ana, California
Dear Mr. Revi:
We are pleased to submit this design level geotechnical engineering investigation report prepared
for the proposed warehouse development to be located at 666 East Dyer Road in Santa Ana,
California. The contents of this report include the purpose of the investigation, scope of services,
background information, investigative procedures, our findings, evaluation, conclusions, and
recommendations. This report supersedes the Preliminary Geotechnical Engineering Investigation
Report, dated February 17,2017, prepared by Moore Twining Associates, lnc. for this proposed
project.
It is recommended that those portions of the plans and specifications that pertain to earthwork,
foundations, pavements and landscaping be reviewed by Moore Twining Associates, Inc. (Moore
Twining) to determine if they are consistent with our recommendations.
ln addition, it is recommended that Moore Twining be retained to conduct construction testing and
inspection services for the excavation, earthwork, pavement, and foundation phases of construction.
A representative with our firm will contact you in the near future regarding these services.
We appreciate the opportunity to be of service. If you have any questions regarding this report, or
if we can be of further assistance, please contact us at your convenience.
Sincerely,
MOORE, TWINTNG ASSOCIATES, INC.
Geotechnical E ngineering Division
..,/'
Read Andersen, RGE
Division Manager
www.moore twining. com
px: 559.2 68.7021
rx: 559.2 68.7126
2527 Fresno Slreel
Fresno, CA 93721
o E,XECUTIVE SUMMARY
This design level geotechnical engineering investigation report was prepared for a proposed
warehouse development to be located at 666 East Dryer Road in Santa Ana, California.
The subject site comprises approximately 25 acres. Nine (9) warehouse type structures are planned
for the proposed development with areas ranging from about 22,000 to 165,000 square feet in plan
area. The project will also include new flexible and rigid pavements for parking areas and truck
access. Appurtenantconstruction is anticipatedto includeundergroundutilities, site lighting, exterior
concrete slabs on grade, and landscaped areas.
As partofan initial preliminaryinvestigation, conductedbetweenDecember22,2016 andDecember
28, 2016, seven (7) test borings were drilled to depths of 2lt/z feet to 5lYz feet below site grade
(BSG). In addition, on Decemb er 23,20l6,seven (7) Cone Penetration Tests (CPTs) were advanced
at the site to depths of about 50 feet BSG. Between March 28,2017 and April 5,2017, twenty-three
(23) test borings were drilled to depths of 2ltA feet to 5l%feet BSG. In addition, on April 29,2017
five (5) Cone Penetration Tests (CPTs) were advancedto depths of about 50 feet BSG. Soil samples
were obtained during the field investigation and tested in the laboratory to determine pertinent
physical and engineering properties.
Based on the findings of the field investigation and laboratory testing program, the proposed
structures can be supported on shallow spread and continuous footings provided the
recommendations presented in this report are followed.
Groundwater was encountered at depths ranging from about 18 feet to 25 feet BSG at the time of our
field investigations in December 2016, and March and April 2017. Based on our review of the CGS
Seismic Hazard Zone Report for the Tustin 7.5 Minute Quadrangle, dated 1998, historic ground
water depths are reported to be about l0 feet BSG in the area of the proposed development.
Based on the findings of this investigation, to reduce the anticipated static foundation settlements
to I inch total and % inch differential in 40 feet, over-excavation below the structures will need to
extend to a minimum depth of 5 feet below preconstruction site grade or a minimum of 2Yz feet
below the bottom of new foundations, whichever is deeper. Undocumented fill soils will also need
to be over-excavated and compacted as part of the preparation of the areas proposed for building
pads. Undocumented fill soils were encountered in one of the soil borings extending to a depth of
about 15 feet BSG.
Based on the former use of the subject property, significant demolition has occurred at the site and
additional demolition of subsurface foundations and other improvements such as existing utilities
and foundations will be required as part of the proposed development. The earthwork subcontractor
will prepare and backfill these excavations per the requirements of the geotechnical report. Of
particular note, it is our understanding that some of the former structures were supported on pile
foundations. These deep foundations will need to be cut off at a depth of at least l0 feet below finish
grade and the resulting excavations backfilled as engineered fill. General recommendations and
precautions regarding this work are discussed in this report.
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o EXECUTM SUMMARY (continued)
Moisture content test results suggest that the soils are considerably over optimum moisture content
and are anticipated to require stabilization. Stabilization could consist of drying the soil to achieve
the specified relative compaction and a stable fill, or place a layer of aggregate base underlain by a
layer of geotextile fabric.
The near surface soils anticipated to be within the zone of construction are high plasticity, medium
expansive clays with high soil moisture contents (as determined at the time of the field
investigation). Based on the presence of expansive soils, an imported non-expansive fill is
recommended below concrete slabs on grade to reduce the potential for excessive heave. In addition,
a minimum 6 inch thick layer of aggregate base is recommended directly below the slabs on grade
(this layer of aggregate base will be located above the environmental liner). The aggregate base
directly below the slab on grade should be a non-recycled material.
Based on our analysis of the CPT data obtained at the project site, a seismic settlement of tp to lYz
inches is estimated. A differential seismic settlement of about % inches over 40 feet was estimated.
As part of the environmental remediation at this site, it is our understanding that soil remediation
will include installation of electrodes to depths of about 30 feet BSG in some areas. It is our
understanding that an electrical current will be applied to the electrodes that will heat the
contaminated soils to temperatures greater than 100 degrees Celsius. It is expected that the moisture
content of the soils treated in this zone will potentially be reduced as part of the treatment. In the
area planned for remediation of volatile organic compounds (VOCs), there is a potential for
movement ofthe surface due to changes in soil volume due to reduction in the soil moisture contents
caused by the remediation method. After the treatment has been completed, the potential exists that
the soils within the area of treatment will experience volume changes until the moisture content of
the treated soils reaches an equilibrium condition.
Given the potential for future soil movement, additional over-excavation, moisture conditioning, and
compaction of the near surface soils may be required in the treatment area in order to reduce the
potential for excessive movement of surface improvements due to the potential for changes in soil
moisture related to the remediation. ln order to further evaluate the depth of soil conditioning and
compaction in this area, a future supplemental geotechnical engineering investigation should include
soil borings in this area following the remediation/cooling period. In addition, periodic survey
monitoring of benchmarks in this area is recommended to assess the magnitude and rate of ground
surface movements and, if any, when stabilizationoccurs.
The environmental remediation system also includes vapor extraction wells. The electrodes, vapor
extraction wells, and other subsurface features of the remediation system will need to be identified
and removed when the remediation activity is complete. Removal should be conducted in
accordance with the recommendations of this report, the recommendations of the environmental
consultant, and all applicable regulatory requirements.
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o EXECUTIVE SUMMARY (continued)
It is our understanding that the proposed structures will require an environmental liner (vapor
mitigation system) below the slabs on grade. The vapor mitigation system will need to be
coordinated with the aggregate base and non-expansive fill section recommended in this report.
The results of analytical tests of soil samples indicated the near surface soils exhibit a
"corrosive"corrosion potential. Chemical analyses indicated a "negligible" to "severe"potential for
sulfate attack on concrete placed in contact with the near surface soils. Based on the test results,
chemical soil treatment is not recommended due to the potential for sulfate induced heave.
This Executive Summary should not be used for design or construction and should be reviewed in
conjunction with the attached report.
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TABLE OF CONTENTS
D5 6620.0t
Page
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3.0
4.0
5.0
6.0
1.0 INTRODUCTION
2.0 PTJRPOSE AND SCOPE OF INVE,STIGATION
2.1 Purpose . .
2.2 Scope . .
BACKGROUND INFORMATION . . . . .
3.1 SiteHistory ....
3.2 SiteDescription .......
3.3 Previous Studies . . . . . . . . . . . . . . .
3.4 Anticipated Construction and Grading
INVESTIGATTVE PROCEDURES
4.1 FieldExploration . . . . . .
4.1 .1 Site Reconnaissance
4.1 .2 Drilling Test Borings
4.1 .3 Soil Sampling . . .
4.1 .4 Cone Penetration Tests
4.2 Backhoe Pit Excavations . . . .
4.3 LaboratoryTesting . . . . . . . . .
FINDINGS AND RESULTS . .
5.1 Surface Conditions . . . . . .
5.2 Soil Profile . .
5.3 Soil Engineering Properties
5.4 Groundwater Conditions .
EVALUATION .
6.1 Demolition and Removal of Existing Site Improvements . .
6.2 Evaluation of Geotechnical Concerns Related to On-Site VOC Treatment
6.3 Faulting and Seismic Design Parameters
6.4 Wet Soils, Stabilization, and Dewatering
6.5 Expansive Soils . .
6.6 Liquefaction and Seismic Settlement . . . . . . . . .
6.7 Static Foundation Settlement and Bearing Capacity
6.8 Asphaltic Concrete (AC) Pavements . . . .
6.9 Portland Cement Concrete (PCC) Pavements . . . .
6. l0 Soil Corrosion
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D5 6620.01
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TABLE, OF CONTENTS
7.0 CONCLUSIONS
8.0 RECOMMENDATIONS
8.1 General ..
8.2 Site Grading and Drainage
8.3 Site Preparation . . . . . . . . .
8.4 Engineered Fill . . . . . . . .
8.5 Shallow Spread Foundations
8.6 lnterior Slabs-on-Grade
8.7 Exterior Slabs on Grade
8.8 Asphaltic Concrete (AC) Pavements . . . .
8.9 Portland Cement Concrete (PCC) Pavements
8.10 TemporaryExcavations . . . . . . . . . . . .
8.ll CorrosionProtections. . . . ... . . .
9.0 DESIGN CONSULTATION
1O.O CONSTRUCTION MONITORING
I1.O NOTIFICATION AND LIMITATIONS
APPENDICES
APPE,NDIX A -Drawings .. .......... ..
Drawing No. I Site Location Map
Drawing No.2 - Test Boring and CPT Location Map
APPENDX B - Logs of Test Borings and CPT Soundings
APPENDIX C - Results of Laboratory Tests
APPENDX D - Summary of Test Pits Excavated for Soil Drying report prepared by
Moore Twining
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o DESIGN LEVEL GEOTECHNICAL ENGINEERING INVESTIGATION
PROPOSED WAREHOUSE DEVELOPMENT
666 EAST DYER ROAD
SANTA ANA, CALIFORNIA
Project Number: D56620.01
1.0 INTRODUCTION
This design level geotechnical engineering investigation report was prepared for the proposed
warehouse development to be located at 666 East Dyer Road in Santa Ana, California. Moore
Twining Associates, Inc. (Moore Twining) was authorized by written agreement to perform this
geotechnical engineering investigation.
The contents of this report include the purpose of the investigation and the scope of services
provided. The previous studies, site description, and the anticipated construction are discussed. In
addition, a description of the investigative procedures used and the subsequent findings obtained are
presented. Finally, the report provides an evaluation of the findings, and general conclusions and
related recommendations. The report appendices contain the drawings (Appendix A), the logs of
borings and CPT soundings (Appendix B), the results of laboratory tests (Appendix C), and the
Summary of Test Pits Excavated for Soil Drying report prepared by Moore Twining (Appendix D).
The Geotechnical Engineering Division of Moore Twining, headquartered in Fresno, California,
performed the investi gation.
2.0 PURPOSE AND SCOPE OF INVESTIGATION
2.1 Purpose: The purpose of this investigation was to conduct a field exploration and
a laboratory testing program, evaluate the data collected during the field and laboratory portions of
the investigation, and provide the following:
2.1.1 Evaluation of the near surface soils in the areas of the proposed foundations
and site improvements;
2.1.2 Conclusions regarding the potential for liquefaction, magnitude of seismic
settlement, and recommendations for California Building Code (CBC)
seismic near source factors and coefficients;
2.1.3 Geotechnical parameters foruse in design of foundations and slabs-on-grade,
(e.g., soil bearing capacity and settlement), and development of lateral
resistance;
2.1.4 Recommendations for site preparation including placement, moisture
conditioning, and compaction of engineered fill soils;
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Design Level Geotechnical Engineering Investigation
Proposed Warehouse Development
666 East Dyer Road
Santa Ana, California
D56620.01
December 18, 2017
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Page No. 2
2.1 .5 Recommendations for the design and construction of new asphaltic concrete
(AC) and Portland cement concrete (PCC) pavements;
2.1.6 Recommendations for temporary excavations and trench backfill; and
2.1 .7 Conclusions regarding soil coffosion potential.
This report is provided specifically for the proposed warehouse buildings and associated
improvements referenced in the Anticipated Construction section of this report. This investigation
did not include a geologic/seismic hazards evaluation, flood plain investigation, tests, environmental
investigation, or environmental audit.
2.2 Scope: Ourproposal, revisedDecember 16,20l6,outlinedthe scope ofourservices
The actions undertaken during the investigation are summarized as follows.
2.2.1 The Rough Grading Plans prepared by Tait (30% Plans), plot date October
13, 2017, were reviewed.
2.2.2 The In-Situ Thermal Remediation Workplan, prepared by ERM, dated
September 2016, was reviewed.
2.2.3 The report entitled "Summary of Environmental Activities - Former ITT
Facility," dated October 7, 2016, and the Addendum to Proposal for
Subsurface Investigation, dated October 28,2016, prepared by Tetra Tech,
were reviewed.
2.2.4 The Preliminary Geotechnical Engineering Investigation Report, prepared by
Moore Twining, identified as ProjectNumberD56620.0l datedFebruary 17,
2017, and the report entitled "Summary of Test Pits Excavated for
Assessment of Soil Drying," prepared by Moore Twining, identified as
Project Number D56620.01 , dated June 9, 2017 , were reviewed.
2.2.5 Permits for test borings and cone penetration test soundings were obtained
from the Orange County Environmental Health Division.
2.2.6 A visual site reconnaissance and subsurface exploration were conducted.
2.2.7 Aerial images of the site from online sources were reviewed.
Shea Propenies (including Mr. Rick Rutecki, Mr. Steve Perales, Mr. Min
Kang, and Mr. Ron Revi) and Tait & Associates, Inc. (Mr. David Sloan) were
consulted during the investigation.
2.2.8
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Design Level Geotechnical Engineering Investigation
Proposed Warehouse Development
666 East Dyer Road
Santa An a,, California
D56620.01
December 18, 2017
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Page No. 3
2.2.9 Laboratory tests were conducted to determine selected physical and
engineering properties of the subsurface soils encountered.
2.2.10 The data obtained from the investigation were evaluated to develop an
understanding ofthe subsurface soil conditions and the engineeringproperties
of the subsurface soils.
2.2.11 This report was prepared to present the purpose and scope, background
information, field exploration procedures, findings, evaluation, conclusions,
and recommendations.
3.0 BACKGROUND INFORMATION
The site history, site description, previous studies, and the anticipated construction are summaized,
in the following subsections.
3.1 Site History: Based on review of online aerial imagery the site has been developed
with office and warehouse buildings since at least 1994. Based on review of the Summary of
Environmental Activities, prepared by TetraTech, the original buildings were reportedly built in the
1950's with several expansions between the 1960's and 1980's. The aerial images dated from 1994
to 2016 indicate the site has been generally the same as the conditions observed during this
investigation, with exception that demolition and environmental remediation were being conducted
during the course of the geotechnical engineering investigation.
3.2 Site Description: The site is bound to the north by East Dyer Road, to the east by
Tech Center Drive with office and warehouse buildings beyond; to the west by office buildings with
South Halladay Street beyond; and to the south by East Alton Avenue and warehouse buildings. The
site comprises an area of about 25 acres. A site location map is provided as Drawing No. I in
Appendix A of this report.
The relatively flat site has previously been developed. It is our understanding that the site is a former
ITT facility. Structures were present at the site and asbestos abatement activities were being
performed during the December 2016 investigation. The building demolition started shortly
following completion of the asbestos removal activities. Demolition of several single-story office
and warehouse/industrial type structures were performed in early 20 I 7. At the time of our latest field
investigation in April 2017 ,the concrete slabs on grade and foundations associated with the previous
buildings remained. At the time of the March and April 2017 investigation, on going soil
remediation activities were being performed within a fenced area near the northern central portion
of the site.
The northern portion ofthe site included landscape areas and some mature trees. Prior to demolition,
some of the structures contained depressed loading dock areas and the floor slab for some of the
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Design Level Geotechnical Engineering Investigation
Proposed Warehouse Development
666 East Dyer Road
Santa Ana, California
D56620.01
December 18, 2017
Page No. 4
structures were elevated above the surrounding grades (dock high floor). The southern portion of
the site was generally covered with asphaltic concrete pavements.
Some of the existing structures are reported to be supported on deep foundations. It is our
understanding deep foundations were exposed in the southwest and eastern portion ofthe site (within
limits of proposed buildings 6, 7, and 8) in excavations conducted adjacent to the exterior
foundations of some of the structures. The general areas where pile foundations were encountered
in excavations by others are noted on Drawing No. 2 in Appendix A.
ln addition, during the recent April2017 investigation, a soil stockpile was noted within the limits
of proposed Building No. 4. The approximate location of the stockpile is shown on Drawing No.
2 in Appendix A.
Overhead lighting and underground utilities were noted throughout the site. In addition, isolated
landscape areas were also noted throughout the site. In addition, several monitoring wells were
noted throughout the site.
3.3 Previous Studies: The referenced documents entitled "Summary of Environmental
Activities - Former ITT Facility," dated Octob er 7 ,2016, and Addendum to Proposal for Subsurface
lnvestigation, dated October 28, 2016, prepared by TetraTech, were reviewed. It is our
understanding that these documents were prepared to summarizethe current known environmental
issues and proposed remediation action activities for the site. Based on review of the referenced
reports, soil contamination, i.e., polychlorinated biphenyl (PCBs), and groundwater contamination,
i.e, volatile organic compounds (VOCs) were reported within the site. Due to the PCB
contamination, the report identified an area in the northern portion of the site that will be required
to be capped due to high levels of PCBs in soil at depths exceeding I foot. The area of groundwater
contamination from VOCs was identified near the eastern site boundary.
Based on review of the referenced In-Situ Thermal Remediation Work Plan, prepared by ERM, dated
September 20 I 6, it is our understanding the VOC treatment will include installation of I 69 Electrical
Resistance Heating Electrodes to depths of about 30 feet BSG. It is our understanding an electrical
current will be applied to the electrodes which will heat the soil to temperatures of greater than 100
degrees Celsius. It is also our understanding that the moisture content of the soils treated in this zone
will vary due to the heating process. It is also our understanding that the VOC remediation treatment
below 30 feetwill involve steam injection to increasevaporpressures ofdissolved gasses to vaporize
and mobilize the VOCs for recovery. The remedial treatment (including installation) is reported to
occur over a period of approximately 5 months. According to the ERM report, it is our
understanding that the system will require a minimum of 60 days for the soil/groundwater to reach
100 degrees Celsius. Once the soil and groundwater reaches optimal temperature, the ERM report
indicates the system will run for approximately 90 days.o
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Design Level Geotechnical Engineering Investigation
Proposed Warehouse Development
666 East Dyer Road
Santa Ana, California
D56620.01
f)ecember 18, 2017
Page No. 5
Based on information included in the September 2016 In-Situ Thermal Remediation Work Plan,
three (3) geologic units were described as a "Shallow lJnit," an "Intermediate Unit," and a "Deep
Unit." Groundwater depths in the "Shallow Unit" were reported to be encountered around l5 to 20
feet BSG, with a potentiometric surface around 5 to 12 feet BSG. Groundwater depths in the
"Intermediate Unit" were reported to be between the depths of 25 and 40 feet BSG, and groundwater
depths in the "Deep Unit" were reported to be around 60 feet BSG.
In addition, the report entitled "Summary of Test Pits Excavated for Assessment of Soil Drying,"
dated June 9,2017, was reviewed. The June2017 report noted that six (6) test pits were excavated
to depths of around 4 to 4.9 feet BSG. Two (2) of the six (6) pits were excavated to approximate
horizontal dimensions of 45 feet by 20 feet (referenced in the report as "large pits," or LP) to assess
the approximate time required for soils to dry to a moisture content that was suitable to achieve the
specified relative compaction. The soils encountered in the pits generally comprised of fat and lean
clays with high moisture contents. Undocumented fill soils were encountered to depths of about I
to2% feet BSG. The undocumented fills comprised silty sand and lean clays. In addition, LP-l
encountered an approximate 12 inch thick section of cement treated a1gre9ate base below the
existing asphalt concrete pavement. The findings of the June 2017 report estimated that the bottom
of excavations and soils spread for drying would require a substantial amount of time to reduce the
soil moisture contents to a range that would be suitable to achieve the specified relative compaction.
In addition, the report indicated that rubber tired mass grading equipment such as scrapers could
impact the Contractors ability to achieve a stable bottom of the over excavation. A copy of the June
2017 report is included in Appendix D of this report for reference.
No other previous geotechnical engineering, geological, or environmental studies conducted for this
site were provided for review during this investigation. If available, these reports should be provided
for review and consideration for this project.
3.4 Anticipated Construction and Grading: The proposed project will include
demolition and removal of the existing structures and subsurface features, i.e., foundations, utilities,
etc., followed by construction of new warehouse buildings and associated site improvements. Nine
(9) warehouse type structures are planned on the site that may range from about 22,000 to 165,000
square feet in plan area.
It is anticipated that the new structures will be one or two story buildings with concrete tilt up walls
and concrete slab on grade construction. The buildings will incorporate loading docks which may
be depressed or dock high construction for truck loading and unloading. Due to the relatively flat
nature of the site, maximum cuts and fills of about 3 to 4 feet were assumed for the purpose of this
report.
The project will also include new asphalt concrete and Portland cement concrete pavements for
parking areas and truck access. Appurtenant construction is anticipated to include underground
utilities, site lighting, exterior concrete slabs on grade, and landscaped areas.
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Proposed Warehouse Development
666 East Dyer Road
Santa Ana, California
D56620.01
f)ecember 18, 2017
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Page No. 6
Based on our experience with similar projects, it is anticipated that typical interior column loads will
be about 85 to 125 kips, with exterior wall loads of about 6 to 8 kips per foot. Floor slab dead and
live loads of about 300 pounds per square foot were also assumed.
Based on information provided by Mr. Jay Neuhaus (ERM), due to the environmental conditions of
the subsurface soils and groundwater, it is our understanding that the proposed construction will
include an environmental liner/membrane below all interior concrete slabs on grade for air quality
conditions inside the proposed buildings.
It is also our understanding that disturbance of subgrade soils will be restricted in a portion of the
northern drive access lane, where a PCB cap is required due to the presence of contaminated soils.
Accordingly, this report includes alternative recommendations for new Portland cement concrete
slabs planned in areas where disturbance of subgrade soils is not permitted due to the PCB cap.
4.0 INVESTIGATIVE PROCEDURES
The field exploration and laboratory testing programs conducted for this investigation are
summarized in the following subsections.
4.1 Field Exploration: The field exploration consisted of a site reconnaissance, drilling
test borings, conducting standard penetration tests, conducting Cone Penetration Tests (CPTs), test
pits, and soil sampling. Permits for the test borings and CPT soundings were obtained from Orange
County Environmental Health Division prior to the start of the field exploration.
4.1.1 Site Reconnaissance: The site reconnaissance consisted of walking the site
and noting visible surface features. The reconnaissance was conducted by a staff engineer on
December 22,2016 and March 28,2017 . ln addition, Harry Moore, Principal Engineer with Moore
Twining, walked the site on September 7,2017 to observe the existing site conditions and to observe
some of the remediation system installation at the site. The features noted are described in the
background information section of this report.
4.1.2 Drilling Test Borings: A total of thirry (30) test borings were drilled within
thesiteaspartofthefieldexploration. FromDecember22,20l6throughDecember2S,20l6,seven
(7) test borings were drilled to depths of 2lYz feet to Slt/zfeetbelow site grade (BSC). Between
March 28,2017 and April 5,2017, twenty three (23) test borings were drilled to depths of 2l%feet
to 5lYz feet below site grade (BSG). The depths of the test borings were selected based on the
anticipated size of the buildings, the type of construction, estimated depths of influence of the
anticipated foundation loads, and the subsurface soil conditions encountered. The borings were
drilled with a truck-mounted CME-75 drill rig equipped with 65/a-inch outside diameter (O.D.)
hollow stem augers. The borings were drilled at the approximate locations shown on Drawing No.
2 in Appendix A. The locations of the borings were limited in some areas due to the presence of
existing structures and ongoing demolition and remediation activities.
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Design Level Geotechnical Engineering Investigation
Proposed Warehouse Development
666 East Dyer Road
Santa Ana, California
D56620.01
December 18, 2017
Page No. 7
During the drilling of the test borings, bulk samples of soil were obtained for laboratory testing. The
soils encountered in the test borings were logged during drilling by a representative of our firm. The
field soil classification was in accordance with the Unified Soil Classification System which
consisted of particle size, color, and other distinguishing features of the soil.
The presence and elevation of free water, if any, in the borings were noted and recorded during
drilling and immediately following completion of the borings.
Test boring locations were determined by pacing and tape measurement with reference to existing
site features. After drilling, the test borings were backfilled with neat cement.
4.1.3 Soil Sampling: Standard penetration tests were conducted in the test borings,
and both disturbed and relatively undisturbed soil samples were obtained. The standard penetration
resistance, N-value, is defined as the number of blows required to drive a standard split barrel
sampler into the soil. The standard split barrel sampler has a 2-inch O.D. and a lg/a-inch inside
diameter (I.D.). The sampler is driven by a 14O-pound weight free falling 30 inches. The sampler
is lowered to the bottom of the bore hole and set by driving it an initial 6 inches. It is then driven
an additional l2 inches and the number of blows required to advance the sampler the additional l2
inches is recorded as the N-value.
Relatively undisturbed soil samples for laboratory tests were obtained by pushing or driving a
California modified split barrel ring sampler into the soil. The soil was retained in brass rings,
2.5 inches O.D. and I -inch in height. The lower 6-inch portion of the samples were placed in close-
fitting, plastic, ainight containers which, in turn, were placed in cushioned boxes for transport to the
laboratory. Soil samples obtained were taken to Moore Twining's laboratory for classification and
testing.
4.1.4 Cone Penetration Tests: On December 23,2016, seven (7) Cone Penetration
Tests (CPTs) were advanced to depths of about 50 feet BSG. On April29,20l7, an additional five
(5) Cone Penetration Tests (CPTs) were advanced to depths of about 50 feet BSG. The CPTs were
conducted at the approximate locations shown on Drawing No. 2 in Appendix A.
The CPT soundingswereperformed byMiddle Earth Geo Testing,Inc. using an electronicpiezocone
with a 60-degree apex angle and a diameter of 38.1 millimeters (about 1.5 inches). The CPT
soundings were hydraulically advanced using a 25-ton CPT rig in accordance with ASTM Test
Method D5778. Measurements of cone tip resistance and sleeve friction data were recorded at
approximate 2 inch intervals during penetration to provide nearly continuous data for interpreting
the engineering properties of the soils. The CPT logs are presented in Appendix B of this report.
The CPT holes were backfilled with neat cement grout in accordance with the requirements of the
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4.2 Backhoe Pit Excavations: Between March 20,2017 and March 28,2017, six (6)
backhoe pits (labeled as TP- 1, TP-2, TP-3 and TP -4, and LP- I and LP-2) were excavated throughout
the site to depths ranging from 4 feet BSG to 4.9 feet BSG. The backhoe pits were excavated under
the direction of a Moore Twining Project Geologist using a Volvo l2lH track excavator with a 48
inch bucket and Case CX 330 with a 54 inch bucket. During the excavation of the backhoe pits, bulk
samples of soil were obtained for laboratory testing. The soils encountered in the backhoe pits were
logged during excavation by a representative of our firm. The field soil classification was in
accordance with the Unified Soil Classification System which consisted of particle size, color, and
other distinguishing features of the soil.
Two of the backhoe pits (LP-1 and LP-2) were left open through April 13,2017 and were regularly
scarified and sampled and tested to determine the moisture content of the soils to evaluate the
duration required for the overly moist soils to dry to a moisture content that would be suitable to
achieve the specified relative compaction. After the soil drying was completed, pits LP- I and LP-2
were backfilled on April 13, 17 and I 8, 201 7 to a minimum of 90 percent relative compaction in
accordance with ASTM Test Method D1557 to a depth of 2 feet BSG.
The findings of the backhoe pit excavations and laboratory data performed on these soils is
summarized in Section 5.0 of this report. Additional information regarding the findings from the
backhoe test pit exploration are included in the referenced June 2017 report included in Appendix
D of this report.
4.3 Laboratory Testing: The laboratory testing was programmed to determine selected
physical and engineering properties of various soil samples. The tests were conducted on disturbed
and relativelyundisturbed samples considered representative of the subsurface soils encountered at
the site.
The results of laboratory tests are summarized in Appendix C. These data, along with the field
observations, were used to prepare the final test boring logs in Appendix B.
5.0 FINDINGS AND RE,SULTS
The findings and results of the field exploration and laboratory testing are summarized in the
following subsections.
5.1 Surface Conditions: At the time of our March and April 20 I 7 field exploration, the
buildings throughout the site had mostly been demolished and the concrete slabs and foundations
from the former buildings generally remained. The ground surface outside the limits of the recently
demolished buildings was covered with asphaltic concrete and Portland cement concrete pavements.
Additional information regarding the surface conditions at the site are described in the "Site
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The asphalt concrete pavements, where encountered, ranged in thickness from about 2Y4to3%inches
and were sometimes underlain by aggregate base ranging in thickness from about Z%to 4Yrinches.
The Portland cement concrete pavements/slabs, where encountered, ranged in thickness from about
4t/tto 12 inches and were sometimes underlain by sand ranging in thickness from about 2 to 4 inches
or by 3 inches of aggregate base as noted at one boring location. It should be noted that cement
treated aggregate base was encountered at the site below the existing pavements, which will be
difficult to excavate and pulverize before it can be used as general fill material (thus, requiring
additional time and effort on behalf of the general contractor).
5.2 Soil Profile: The near surface soils encountered in the test borings and CPTs below
the existing pavements generally consisted of lean clays with interbedded layers of silty sands and
clayey sands to the maximum depth explored of 50 feet BSG. It should be noted that one test boring
(B-5), located within the eastern portion of the site in the area of the planned VOC remediation,
encountered undocumented fill soils to a depth of about l5 feet BSG. Test borings B-19, B-20, B-
27, and B-28, drilled within approximately 50 feet horizontally of test boring B-5 encountered
undocumented fills to depths of about 3 to 5 feet BSG. In addition, test borings B-12, B-13, B-15,
8-16, and B-17 encountered shallow fills (less than 5 feet BSG). The undocumented fills
encountered throughout the site generally consisted of silty sand, sandy lean clay, and lean clays
soils. The locations and depths of undocumented fills encountered at the boring locations are
depicted on Drawing No. 2 in Appendix A of this report.
The June 2017 Test Pit report encountered an average of about 2Yzinches of asphaltic concrete
pavement in LP- I and LP-2. At LP- I , the asphaltic concrete pavements were underlain by l2 inches
of cement treated aggregate base and atLP-Zthe asphaltic concrete pavements were underlainby 9%
inches of aggregate base. The smaller test pits, TP-l through TP-4, encountered Portland cement
concrete pavements ranging in thickness from 3 to 8 inches.
The backhoe pit excavations excavated in March 2017 generally encountered undocumented fill soils
from below the existing pavements to depths ranging from I to 2Yz feet BSG. The undocumented
fill soils comprised silty sand and lean clay soils. Below the undocumented fills, native lean clay
and fat clay soils were encountered to the maximum depths explored in the backhoe pit excavations
of 4.9 feet BSG. The soils observed in the backhoe pit excavations were generally consistent with
those encountered in the soil borings.
The foregoing is a general summary of the soil conditions encountered during this investigation.
Detailed descriptions of the soils encountered at each test boring location are presented in the logs
of borings in Appendix B. The stratification lines in the logs represent the approximate boundary
soil types; the actual in-situ transition may be gradual.
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5.3 Soil Engineering Properties: The descriptions of the soil engineering properties as
determined from our field exploration and laboratory testing are as follows.
Undocumented Fills: The undocumented fill soils were described as medium stiff to hard lean
clays, as determined by standard penetration resistance, N-values ranging from 6 to 32 blows per
foot. The undocumented fill soils described as silty sands were loose to medium dense, as
determined by standard penetration resistance, N-values ranging from 6 to l6 blows per foot. The
moisfure content of the fill soils tested ranged from 7 to 27 percent. An Atterberg limits test of these
soils indicated a plasticity index of 23 and a liquid limit value of 37. An expansion index test
performed on these soils indicated an expansion index of 85.
Fat Clays [CH]: The fat clay soils tested had moisture contents ranging from about 14 to 24
percent.
Lean Clays and Sandy Lean Clays [CLl: The lean clays and sandy lean clays were soft to very
stiff, as determined by standard penetration resistance, N-values, ranging from 3 to 26 blows per
foot. The moisture contents of the samples tested ranged from about 14 to 31 percent. Thirry six
(36) relatively undisturbed samples revealed dry densities ranging from 79.3 to 105.7 pounds per
cubic foot (pcf). The results of nine (9) consolidation tests ranged from about 9.5 to 14.5 percent
consolidation under a load of 16 kips per square foot. The samples exhibited a swell ranging from
about 0.1 to 2.I percent when wetted under a load of 500 pounds per square foot. The results of
twelve (12) Atterberg limits tests indicatedplasticity indexes ranging from 7 to 32 with liquid limit
values ranging from27 to 47. The results of four (4) direct shear tests indicated internal angles of
friction ranging from 21 to 36 degrees with cohesion values ranging from zero (0) to 1,280 pounds
per square foot. The results of five (5) expansion indexes tests performed on these soils indicated
expansion index values of72,80, 80, 81, and 84.
Four (4) relatively undisturbed samples collected from the area of the proposed VOC heatment zone
between depths of 5 and l5 feet BSG were evaluated to assess the behavior of the soils when they
were dried and subsequently wetted near the in-situ overburden pressure. The intent of the testing
was to obtain data for consideration of the subsurface soil response to the proposed soil remediation
work. The results of these tests are summarized in Table No. 1 below:
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Table No. 1
o * Desiccation cracking in sample during drying may have disturbed sample, resulting in collapse
Silty Sands [SMl: The silty sands encountered were described as medium dense, as determined by
standard penetration resistance, N-values, of 14 to l8 blows per foot.
Clayey Sands [SC]: The clayey sands encountered were described as medium dense, as determined
by a standard penetration resistance, N-value, of 26 blows per foot.
Poorly Graded Sand with Silt [SP-SMI: The poorly graded sand with silt encountered were
described as medium dense, as determined by a standard penetration resistance, N-value of 20 blows
per foot.
R-value Tests: The results of six (6) R-value tests performed on bulk samples of the near surface
clays indicated R-values ranging from 8 to 27.
Maximum Density/Optimum Moisture: Maximum density/optimum moisture tests (ASTM
D 1557) performed on eight (8) near surface samples indicated maximum dry densities ranging from
108.5 pounds per cubic foot to 127.3 pounds per cubic foot with optimum moisture contents ranging
from 10.6 percent to l7.l percent.
Chemical Tests: Chemical tests were performed on seven (7) near surface samples, which indicated
pH values of 7 .7 ,7.8, 8.0, 8.0, 8.0, 8.1, and 8. l; minimum resistivity values of 3,068, 3,068, 3,068,
3,068, 3,335,3,735,3,735,and4,402ohms-centimeter; sulfate concentrations of 0.013,0.015, 0.037,
0.46,0.62,0.64, and 0.64 percent by weight; and chloride concentrations of 0.01 l, 0.0054, 0.0065,
0.0070, 0.0088, 0.0090, and 0.0091 percent by weight.
Boring Depth,
BSG
(feet)
Overburden
Pressure
(ps0
Initial
Wet
Density
Before
Drying
(pc0
Percent
Shrinkage
When Dried
from Initial
Moisture to 0o/o
Moisture
Content
Percent
Swell When
Saturated at
0"/,
Moisture,
After Drying
Final Wet
Density,
After
Swelling
from
Saturation
(pc0
B-6 5-6.5 6s0 123.9 3.8 4.5 122.5
B-6 15- 16.5 1,950 122.3 9.7 -1.3*136.0
B-7 5-6.5 6s0 r20.5 3.9 3.7 t2t.1
B-7 l5- 16.5 1,950 115.0 8.8 2.2 I 32 1
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5.4 Groundwater Conditions: Groundwater was encountered at a depth of about I 8 feet
BSG at the time of our investigation. Due to Orange County's requirements for grouting the soil
borings, the boreholes were not left open for an extended period of time to measure the stabilized
groundwater level. Thus, it should be noted that the first encountered groundwater depths identified
in the soil borings are not considered stabilized groundwater depths. Groundwater monitoring by
others has identified shallower groundwater conditions (5 to l0 feet +l-) at the site. Furthermore,
based on review of the CGS SeismicHazard Zone Report for the Tustin 7.5 Minute Quadrangle,
dated 1998, historic ground water depths are reported to be about 10 feet BSG.
6.0 E,VALUATION
The data and methodology used to develop conclusions and recommendations for proj ect design and
preparation of construction specifications are surlmarized in the following subsections. The
evaluation was based upon the subsurface soil conditions determined from the field exploration and
Iaboratory testing program and our understanding of the proposed construction. The conclusions
obtained from the results of our evaluations are described in the Conclusions section of this report
6.1 Demolition and Removal of Existing Site Improvements: At the time of our latest
field exploration, demolition of the existing structures was in progress. The concrete slabs on grade
and foundation systems from the former buildings remained in place throughout the site. Outside
of the limits of the areas of previous structures, concrete flatwork and/or Portland cement concrete
or asphaltic concrete paving were also present throughout the site.
Due to the previous development of the site, there is a potential for unknown subsurface structures
and areas of undocumented fill to be encountered during site demolition and grading. As part of the
site preparation for the new improvements, all existing surface and subsurface improvements (i.e.,
foundations, utilities, subsurface structures, etc.) and undocumented fills should be removed and the
excavations backfilled with engineered fill. ln addition, it will be critical to over-excavate the soils
which are disturbed due to the demolition and removal of the existing improvements to reduce the
potential for excessive settlement resulting from soil disturbance. The environmental remediation
system that was installed and operated during the course of our investigation included the installation
of extraction wells, probes, etc. When remediation is complete, the subsurface components of the
remediation system will need to be identified and properly backfilled with cement grout.
Based on information provided by Mr. Steven Perales, it is our understanding that some of the
existing structures located in the southwest and eastern portion of the site were supported on concrete
piles located about 6 feet on center. Based on the information provided, these piles appear to be
within proposed Building 6, BuildingT, and Building 8. The general areas on the site that are known
to include piles are noted on Drawing No. 2. However, it should be noted that the type of foundation
system for all of the previous structures are not known. Where piles are encountered, the piles
should be removed to a depth of about 10 feet below grade in areas where new buildings with
shallow foundations are planned. Removal of the piles in paved areas could be reduced to a depth
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of 5 feet. The general contractor will need to remove the piles in a manner that does not disftrrb the
soils around the piles during the removal. The reinforcing steel will need to be cut off in a neat
manner to allow placement of compaction of fill soils around and directly above the remaining piles.
If the soils are disturbed during removal of the piles, the contractor will be required to compact the
disturbed soils as engineered fill as specified in this report. After the piles are removed, the
contractor will be required to compact all fill around the remaining pile. It is anticipated this work
will require small hand operated equipment to fill to a sufficient thickness that will allow compaction
with typical earthmoving equipment to operate over the tops of the piles. A suitable excavation will
also be required to allow in-place density tests to be conducted by a soil inspector to verifu that the
soils around and above the pile have been compacted as specified in this report.
Approximately 12 inches of cement treated base was encountered below the asphaltic concrete
pavements at the location of LP-l (performed as part of the referenced June 2017 test pit
investigation). The presence of cement treated base could not be clearly determined in any of the
small diameter test borings or CPTs; therefore, the approximate horizontal extent of the cement
treated base material is unknown. The Contractor should anticipate increased diffrculty and time to
remove and process the cement treated base material.
As part of the site preparation, existing trees, all root systems and soils with more than 3 percent
organics should be removed and not used as engineered fill.
The existing asphaltic concrete material and Portland cement concrete material could be considered
for processing and reuse as an engineered fill or potentially an aggregate base material outside of
buildings. Fill materials containing recycled asphalt concrete are not recommended below the
buildings unless the environmental liner planned below the structures would provide sufficient
protection to address potential indoor air quality concerns. If the existing concrete materials can be
segregated from the asphalt concrete, it may be possible to process concrete to create an engineered
fill material that does not contain asphalt concrete. If the materials were proposed for use as
engineered fill outside of building areas, the asphalt and concrete would need to be processed by
crushing and screening the material to reduce the maximum particle size to less than 3 inches and
thoroughlymixedto createawell-gradedmaterialwith more than 75 percentpassingtheNo.4 sieve.
Crushing to smaller particle sizes may be required to generate a well-graded mixture. It should be
noted that the aggregate base directly below the slabs on grade will be located above the
environmental liner; thus, this material is recommended to be a non-recycled material unless
specifically approved by the owner.
6.2 Evaluation of Geotechnical Concerns Related to On-Site VOC Treatment:
Based on our review of the VOC treatment plan discussed in the "ln-Situ Thermal Remediation
Workplan," prepared by ERM, dated September 2016, it is our understanding that the soils within
the proposed VOC treatment area to a depth of about 30 feet will be heated to 100 degrees Celsius.
This process will result in variations in the moisture content of the soils within the upper 30 feet.
It is our understanding the system will require approximately 60 days to heat the soil/groundwater
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to achieve the desired temperature. Once the target temperature is reached, the treatment will
continue for an additional 90 days to allow for VOC extraction. The remediation workplan also
indicates it will take 4 to 5 months for the soil to cool following treatment. The approximate area
oftreatment is depicted on Drawing No. 2 in Appendix A of this report. The final limits of treatment
will be determined by others.
Due to the high soil temperatures anticipated for the soil remediation treatment to be conducted
within the upper 30 feet BSG in some areas, the potential for ground deformation/shrinkage as a
result of the drying and subsequent wetting of these soils were assessed. As part of the laboratory
testing for this investigation, four (4) relatively undisturbed samples were tested to simulate the
effects of drying the soil to zero moisture content and subsequent saturation. Based on the results
of these tests, on a preliminary basis, a few inches of settlement of the clay soils could potentially
occur due to drying shrinkage and compression of the clay soils under the existing overburden
loading. After remediation is complete, the soils are anticipated to exhibit an increasedpotential for
swell until the moisture conditions achieve equilibrium. Thus, it is recommended that survey
benchmarks be installed at the ground surface in the heatment area to monitor surface settlement and
rebound during and after the VOC treatment. This information should be provided to Moore
Twining for review.
After soil remediation, the soils above the groundwater level will take longer to return to "natural"
or equilibrium moisture contents as compared with the soils below groundwater. Depending on the
moisture conditions at the time of grading, additional over-excavation and moisture conditioning
may be required to moisture condition the upper soils and reduce potential impacts from future soil
movement. ln order to evaluate restoration of the moisture content of the soil after the remediation,
a supplemental geotechnical investigation should be conducted in this area following the soil
treatment.
6.3 Faulting and Seismic Design Parameters: The site is not located in an Alquist-
Priolo Earthquake Fault Zone. Based on review of the CGS 2010 Fault Activity Map of California,
the nearest active fault is the Newport-lnglewood Fault, which is located about 9 miles west of the
site. Therefore, the potential for fault rupture at the site is considered low.
It is our understanding that the 2016 CBC will be used for structural design, and that seismic site
coefficients are needed for design. Based on the 2016 CBC, a Site Class E represents on-site soil
conditions with standard penetration resistance, N-values averaging less than 15 blows per foot in
the upper 100 feet below site grade. Recommendations for the seismic coefficients and eanhquake
spectral response acceleration values are provided in this report. A Maximum Considered
Earthquake (geometric mean) peak ground acceleration adjusted for site effects (PGAM) of 0.5149
was determined for the site using the Ground Motion Parameter Calculator provided by the United
States Geological Survey(http://earthquake.usgs.gov/designmaps/us/application.php). This ground
acceleration and a Maximum Considered Earthquake magnitude of 7.3 was used in our liquefaction
and seismic settlement analysis (see Section 6.6 of this report) based on deaggregation analysis
(United States Geological Surveydeaggregation websitehttp://geohazards.usgs.gov/deaggint/20O8).
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6.4 Wet Soils. Stabilization. and Dewatering: The test borings generally encountered
near surface, very moist clay soils. Based on the results of laboratory testing conducted as part of
this investigation, the near surface soils encountered in the test borings drilled were approximately
6 to 20 percent above optimum moisture content. The moisture content of the samples tested from
the June 201 7 test pit excavations were reported to be near optimum to as high as I 9 percent above
optimum moisture. Considering the shallow depth to groundwater anticipated at the site (see Section
5.4 of this report), it should be anticipated that the near surface soils will require air drying and/or
chemical stabilization prior to placement of fill soils, structures, or pavements.
Based on the results of the analyical chemistry testing conducted as part of this investigation, due
to the high sulfate content of the near surface soils and the risk of sulfate induced heave, chemical
soil treatment is not recommended at this site. Due to wet soil conditions, it may be possible to dry
the soils in the bottom of the over-excavation by continual discing and aeration to allow for the soils
to be compacted and achieve a stable fill. However, due to the fine-grained nature of the soils, high
moisture contents below the zone of drying may still result in unstable conditions. Accordingly,
overly moist soil conditions could be stabilized by placement of bridge lifts in the areas of over-
excavation. Bridge lifts should include additional over-excavation followed by placement of an
approximate 12 to l8 inches (or as needed to stabilize the subgrade soils) layer of class 2 aggregate
base or crushed miscellaneous base compacted as engineered fi[ underlain by alayer of geotextile
fabric such as Mirafi 600X. As an alternative, an open graded crushed aggregate material could be
used for a bridge lift material, provided the open graded material is fully encapsulated in a geotextile
fabric. It may also be possible to use crushed concrete from building demolition (with geotextile
fabric) for stabilization in the bottom of areas of over-excavation.
Due to the high soil moisture contents, the excavated soils will need to be dried to achieve a moisture
content at which the soils can be placed and compacted as engineered fill. The Contractor should
consider placing the soil on a "mixing table" and repeatedly tilling the soil to enhance drying by
aeration. It has been our experience that processing the "wet" soil with a "traveling pug mill" could
also aid in the aeration of "wet" soils.
In addition, it should be anticipated that overly moist soils will be encountered in the deeper utility
excavations for the project. Thus, dewatering and stabilization of the bottom of the utility
excavations should also be anticipated as part of construction. Where excavations are required
below groundwater, dewatering should be conducted and groundwater will need to be managed. Due
to the environmental conditions at the site (soil and groundwater impacts), special design
requirements, backfill, and/or trench cutoffs may be necessary to address potential concerns with
migration of contaminants in utility trenches. Due to the granular nature of bedding and pipe zone
backfill, undergroundutilities can becomepaths foracceleratingmigration ofimpacted groundwater.
If this is a concern, a special backfill material with lower permeability may be required for utility
trenches. It is recommended these conditions, and the compatibility ofunderground piping systems,
be evaluated by the environmental consultant as part their assessment of the site. A project specific
dewatering design will need to be prepared and monitored by the contractor's dewatering consultant.
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Also, it is anticipatedthat deeperundergroundutilities and associated subsurface structures will need
to be designed to consider potential buoyant conditions based on the shallow groundwater
conditions.
6.5 Expansive Soils: One of the potential geotechnical hazards evaluated at this site is
the expansion potential of the near surface soils. Over time, expansive soils will experience cyclic
drying and wetting as the dry and wet seasons pass. Expansive soils experience volumetric changes
(shrink/swell) as the moisture content of the clayey soils fluctuate. These shrink/swell cycles can
impact foundations and lightly loaded slabs-on-grade when not designed for the anticipated
expansive soil pressures. Expansive soils cause more damage to structures, particularly light
buildings and pavements, than any other naturalhazard,including earthquakes and floods (Jones and
Holtz,1973). Expansion potential may not manifest itself until months or years after construction.
The near surface soils are anticipated to be predominantly lean clays with a medium potential for
expansion based on expansion indexes of 72,80, 80, 81,84, and 85. Accordingly, measures to
reduce the impacts of expansive soils movement will need to be incorporated into the project design
and earthwork recommendations. This report includes recommendations for placing an imported,
non-expansive fill over moisture conditioned subgrade soils below concrete slabs on grade to reduce
the potential for excessive heave. Depending on the effectiveness of recycling onsite concrete
material, it may be possible to recycle concrete from the building demolition to create a non-
expansive fill material for use below concrete slabs on grade. ln addition, the moisture contents of
the near surface clay soils will need to be assessed after completion of the soil remediation work
described in this report.
To reduce the risk of swell related damage to exterior flatwork and PCC pavements, these slabs
should also be underlain by a non-expansive fill over subgrade soils which are moisture conditioned
and compacted as recommended in this report.
6.6 Liquefaction and Seismic Settlement: Liquefaction and seismic settlement are
conditions that can occur under seismic shaking from earthquake events. Liquefaction describes a
phenomenon in which a saturated, cohesionless soil loses strength during an earthquake as a result
of induced shearing strains. Lateral and vertical movements of the soil mass, combined with loss
of bearing usually results. Fine, well sorted, loose sand, shallow groundwater conditions, higher
intensity earthquakes, and particularly long duration of ground shaking are the requisite conditions
for liquefaction.
Based on review of the Seismic HazardZone Map of the Tustin Quadrangle, dated January 17 ,2001,
the site is located in a liquefaction hazard area.
Liquefaction and seismic settlement analyses were conducted based on soil properties obtained by
cone penetration test (CPT) soundings CPT-I through CPT-12 using the computer program
LiquefyPro, developed by CivilTech Software. A Maximum Considered Earthquake (geometric
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mean) peak ground acceleration adjusted for site effects (PGAM) of 0.514g was determined for the
site usingthe GroundMotion ParameterCalculatorprovidedbythe United States Geological Survey
(http://earthquake.usgs.gov/designmaps/us/application.php). A Maximum Considered Earthquake
magnitude of 7.3 was used in the analysis based on deaggregation analysis (United States Geological
Survey deaggregation website http://geohazards.usgs.gov/deaggint/2008). This magnitude
corresponds to the predominant earthquake magnitude contributing to the ground motion. Soil
parameters, such as wet unit weight, tip resistance, and sleeve friction were input from the CPT data
for the soil layers encountered throughout the depths explored. A groundwater depth of 5 feet BSG
was used in the analysis.
Analysis of seismic settlement based on the CPT data indicate an estimated total seismic settlement
of up to I % inches and a differential seismic settlement of 3/t inch over a horizontal distance of 40
feet. In general, one to three foot thick layers of liquefiable soils were identified between depths of
about 20 feet and 25 feet BSG and between depths of 30 and 40 feet BSG.
6.7 Static Foundation Settlement and Bearing Capacity: The potential for excessive
total and differential static settlements of foundations and slabs on grade is a geotechnical concern
that was evaluated for this project. The increases in effective stress to underlying soils which can
occur from new foundations and structures, placement of fill, withdrawal of groundwater, etc. can
cause vertical deformation of the soils which can result in damage to the overlying structure and
improvements. The differential component of the settlement is often the most damaging. In
addition, the allowable bearing pressures of the soils supporting the foundations were evaluated for
shear and punching type failure resulting from the imposed foundation loads.
An analysis of static settlement was conducted based on the results of consolidation tests performed
for this investigation. The results indicate that a shallow spread foundation supported directly on
native soils would be subject to a total static settlement of abofi IYz inches. The analysis assumed
a foundation depth of 2 feet and an allowable bearing pressure of 2,000 pounds per square foot.
To reduce total and differential static settlements to I inch and Yz inch differential in 40 feet,
respectively, it was estimated that building foundations should be supported on a minimum of 2%
feet of compacted engineered fill. ln addition, the soils disturbed from demolition and removal of
existing surface and subsurface improvements will need to be recompacted as part of the site
preparation.
6.8 Asphaltic Concrete (AC) Pavements: Recommendations for asphaltic concrete
pavement structural sections are presented in Section 8.8 of this report. The results of the R-value
testing indicated the near surface soils have poor to fair pavement support characteristics (R-values
ranging from 8 to 27). For the purpose of this report, considering the extent of grading anticipated,
asphaltic concrete pavement section recommendations were prepared based on an R-value of 10.
The structural sections were designed using the gravel equivalent method in accordance with the
California Department ofTransportation HighwayDesign Manual. The analysis was based on traffic
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index values ranging from 5.0 to 10.0. The appropriate paving section should be determined by the
project civil engineer or applicable design professional based on the actual vehicle loading (traffic
index) values. If traffic loading is anticipated to be greater than assumed, the pavement sections
should be re-evaluated.
It should be noted that if the pavements are constructed prior to the building construction, the
additional construction truck traffic should be considered in the selection of the traffic index value.
If more frequent or heavier traffic is anticipated and higher Traffic Index values are needed, Moore
Twining should be contacted to provide additional pavement section designs.
6.9 Portland Cement Concrete (PCC) Pavements: Recommendations for onsite
Portland cement concrete (PCC) structural sections are presented in Section 8.9 of this report. The
PCC pavement sections are based upon the amount and type of traffic loads being considered and
the pavement characteristics of the subgrade soils that will support the pavement. The measure of
the amount and type of traffic loads were based upon an index of equivalent axle loads (EAL) from
the loading of heavy trucks called a traffic index (T.I).
In evaluation of the pavement design for this project, samples of the near surface soils anticipated
to be representative ofthe soils which will support pavements were obtained and R-value testing was
performed in accordance with Califomia Test Method 301. The R-value test results are summarized
in Appendix C of this report. These data were used with published correlations to estimate a
modulus of subgrade reaction value for use in the pavement design.
Therecommendationsprovided in this reportforPCC pavements arebasedon traffic indices ranging
between 5.0 and 10.0 and the design procedures contained in the Portland Cement Association
"Thickness Design of Highway and Street Pavements." The PCC pavement sections were designed
for a life of 20 years, a load safety factor of 1.1, a semi-truck single axle weight of 12,000 pounds
with lwo (2) tandem axles of 34,000 pounds each. A modulus of subgrade reaction, K-value, for the
pavement section, of 150 psi/in was used for the pavement design.
Due to the expansive soils, Portland cement concrete pavements should be supported on a mrnimum
of 12 inches ofaggregate base.
It is our understanding that disturbance of subgrade soils will be restricted in a portion of the
northern drive access lane where a PCB cap is required due to the presence of contaminated soils.
According to Shea Properties, it is our understanding the remediation contractor will place 6 inches
ofasphaltic concrete over 6 inches ofclass 2 aggregate base, over proofrolled subgrade soils as a
cap in this area. It is also our understanding that during construction, a new Portland cement
concrete pavement and aggregate base will be constructed over the asphaltic concrete section. Based
on our understanding of the design grades in the area of the PCB cap, it has been assumed that a
minimum of 6 inches of aggregate base (the actual thickness of the aggregate base section will
depend on the final design grade in the area of the PCB cap) will be placed below the PCC pavement
in the PCB cap area. If the thickness of the aggregate base has to be reduced and given the
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restriction to disturbance/preparation ofthe subgrade soils, the PCC pavement in the area ofthe PCB
cap will have an increased potential for movement. Therefore, for this area, increased PCC thickness
is recommended in this area in Section 8.9 of this report. In addition, to reduce the width of cracks
in the concrete pavement, reinforcement of the PCC pavement in the PCB cap area would be
suggested.
6.10 Soil Corrosion: The risk of corrosion of construction materials relates to the
potential for soil-induced chemical reaction. Corrosion is a naturally occurring process whereby the
surface of a metallic structure is oxidized or reduced to a corrosion product such as iron oxide (i.e.,
rust). The metallic surface is attacked through the migration of ions and loses its original strength
by the thinning of the member.
Soils make up a complex environment for potential metallic corrosion. The corrosion potential of
a soil depends on numerous factors including soil resistivity, texture, acidity, field moisture and
chemical concentrations. In order to evaluate the potential for corrosion of metallic objects in
contact with the onsite soils, chemical testing of soil samples was performed by Moore Twining as
part of this investigation. The results of the tests are included in Appendix C of this report.
Conclusions regarding the corrosion potential of the soils tested are included in the
Recommendations section of this report based on the National Association of Corrosion Engineers
(NACE) corrosion severity ratings listed in Table No. 2, below.
Table No. 2
Soil Resistivity (ohm cm)Corrosion Potential Rating
>20,000 Essentially non-corros ive
10,000 - 20,000 Mildly corrosive
5,000 - 10,000 Moderately corrosive
3,000 - 5,000 Corrosive
I ,000 - 3,000 Highly corrosive
< 1,000 Extremely corrosive
The results of soil sample analyses indicate that the near-surface soils exhibit a "corrosive" corrosion
potential to buried metal objects.
Ifthe manufacturers or suppliers cannot determine ifmaterials are compatible with the soil corrosion
conditions, a professional consultant, i.e., a corrosion engineer, with experience in corrosion
protection should be consulted to provide design parameters. Moore Twining does not provide
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6.11 Sulfate Attack of Concrete: Degradation of concrete in contact with soils due to
sulfate attack involves complex physical and chemical processes. When sulfate attack occurs, these
processes can reduce the durability of concrete by altering the chemical and microstructural nature
of the cement paste. Sulfate attack is dependent on a variety of conditions including concrete
quality, exposure to sulfates in soil/groundwater and environmental factors. The standard practice
for geotechnical engineers in evaluation of the soils anticipated to be in contact with concrete is to
perform testing to determine the sulfates present in the soils. The test results are then compared with
the provisions of ACI 318, Section 4.3,to provide guidelines for concrete exposed to sulfate-
containing solutions. Common methods used to resist the potential for degradation of concrete due
to sulfate attack from soils include, but are not limited to, the use of sulfate-resisting cements, air-
entrainment and reduced water to cement ratios.
The results of soil sample analyses indicate that the near-surface soils exhibit a "negligible" to
"severe" potential for sulfate attack on concrete placed in contact with the near surface soils. Due
to the high sulfate condition, chemical (i.e., cement, lime, etc.) treatment of the soil is not
recommended for this site. The soil corrosion data should be provided to the manufacturers or
suppliers of materials that will be in contact with soils (pipes or ferrous metal objects, etc.) to
provide assistance in selecting the protection and materials for the proposed products or materials.
Ifthe manufacturers or suppliers cannot determine if materials are compatible with the soil corrosion
conditions, a professional consultant, i.e., a corrosion engineer, with experience in corrosion
protection should be consulted to provide design parameters.
7.0 CONCLUSIONS
Based on the data collected during the field and laboratory investigations, our geotechnical
experience in the vicinity of the project site, and our understanding of the anticipated construction,
the following general conclusions are presented.
7.1 The results of this geotechnical engineering investigation indicate the site is suitable
for the construction of the proposed warehouse structures with regard to support of
the proposed improvements described in this report, provided that the project design
and construction incorporates measures to address the concerns associated with static
settlement, seismic settlement and expansive soils as presented in this report.
The project site was formerly occupied by an ITT facility. The above ground
portions of the structures have been demolished; however, the foundations and slabs
on grade of the former structures still exist. It is our understanding that some of the
former structures were supported by piles. The former foundations, slabs on grade,
piles and other subsurface items such as utilities, etc. will be required to be removed.
Given the extent of these items, the Contractor will need to take precautions to ensure
the removal of all loose soils resulting for the demolition of these items and the
proper backfill of the resulting excavations. It is our understanding that the
excavations resulting from the demolition of these items will be left open and these
7.2
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7.4
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areas will be prepared by the contractor and backfilled as engineered fill as
recommended in this report.
It is our understanding that soil and groundwater on portions of this site are
contaminated with PCBs, VOCs, etc. related to the former use of the property. ITT
was conducting remediation of the site during our geotechnical engineering
investigation. The remediation system consists of subsurface probes, vapor
extraction wells, etc. These subsurface components will need to be properlyremoved
and/or backfilled below a depth of l0 feet from finish grade and the upper 10 feet of
these components removed and the resulting excavations, if any, properly backfilled
as specified in this report. In addition, it is our understanding that the ITT
remediation contractor has excavated portions of the site to remove contaminated
soils. It is our understanding that these excavations will be left open and the
excavations will be prepared and backfilled by Shea Properties' Contractor in
accordance with the recommendations of this report.
The subsurface soils encountered in the test borings and CPTs generally consisted of
lean clays with interbedded layers of silty sands and clayey sands to the maximum
depth explored of 50 feet BSG. It should be noted that one test boring (B-5), located
within the eastern portion of the site in the area of the planned VOC remediation,
encountered undocumented fill soils to a depth of about 15 feet BSG. Test borings
B- I 9, B-20, B-27 , andB-28, drilled within approximately 50 feet horizontally of test
boring B-5 encountered undocumented fills to depths of about 3 to 5 feet BSG. In
addition, isolated areas with relativelyshallow fills (less than 5 feetBSG) were noted
in test borings B-12, B-13, B-15, 8-16, and B-17. The undocumented fills
encountered throughout the site generally consisted ofsilty sand, sandy lean clay, and
lean clays soils. In addition, a cement treated base material was encountered at the
location of LP-1.
The near surface soils encountered were primarily lean clays with a medium
expansion potential. Due to the expansive soil conditions, an imported, non-
expansive fill is recommended below concrete slabs on grade in the proposed
buildings to reduce the potential for excessive heave. ln addition, a layer of non-
expansive fill is recommended below PCC pavements to reduce the potential for
excessive heave of the PCC pavements.
Groundwater was encountered in the borings at a depth of about l8 feet below site
grade. However, the borehole were not left open for an extended period of time to
allow for groundwater to stabilize. Thus, the actual stabilized groundwater depths
are anticipated to be shallower. Groundwater monitoring at the site by others has
identified shallower groundwater (5 to l0 feet +/-) at the site.o
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7 .7 Based on the site preparation recommendations of this report, static settlements of
I inch total and % inch differential in 40 linear feet should be anticipated for
foundation design.
7.8 Laboratory testing suggests that the near surface soils encountered in the soil borings
are considerably over optimum moisture content (6 to 20 percent). In addition,
laboratory testing performed on samples tested from the test pit excavations were
determined to be near optimum to 19 percent above optimum moisture. Thus, it
should be anticipated that the site soils will require stabilization of areas which are
over-excavated, and aeration ofwet soils to allow for compaction of the soils as part
of the site preparation and construction of building pads.
7.9 Based on review of the Seismic HazardZone Map, Tustin Quadrangle dated January
17,200L, the site is mapped in a liquefactionhazard zone. Analysis of seismic
settlement based on the CPT data indicate estimated seismic settlements of up to I %
inches total and a differential seismic settlement of about 3/+ inch over 40 feet.
o 7.10 The potential for fault rupture due to a known fault at the site is considered low
7.ll In the area planned for remediation of VOCs noted on Drawing No. 2, on a
preliminary basis, due to the predominately clayey nature of the soils encountered
within the upper 30 feet BSG, there is a potential for surface movement due to
variations of the moisture content of the underlying clay soils related to the
remediation of contaminated soils in this area. After the remediation is completed,
it is anticipated that the near surface soils above groundwater would remain
significantly below optimum moisture content for some time and would possess an
increased potential for expansive soil type heave when wetted in the future.
Therefore, additionalover-excavation, moisture conditioning, and compaction ofthe
near surface soils may be required in the VOC treatment area in order to reduce the
potential forexcessive heave of surface improvements due to the deep dryrng ofsoils
anticipated from the proposed remediation. In order to further evaluate the depth of
soil conditioning and compaction in this area,itis recommended that a supplemental
geotechnical investigation be performed in this area following the cooling period
after treatment. In addition, monitoring of potential surface settlement is
recommended in this area by monitoring of survey benchmarks.
7.12 Due to the expansive nature of the near surface soils and the relatively low
permeability of the clay soils, storm water infiltration systems are not recommended
for the proposed development.
7 .13 For planning purposes, an earthwork shrinkage estimate ranging from l0 to 15 (+/-)
percentwouldbeanticipated. Earthworkshrinkageissubjecttosignificantvariations
due to many factors.
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7.14 Results of testing of soil samples indicated the near surface soils tested exhibit a
"corrosive"corrosion potential. Chemical analyses indicated a "negligible" to
"severe" potential for sulfate attack on concrete placed in contact with the near
surface soils.
8.0 RECOMMENDATIONS
Based on the evaluation of the field and laboratory data, and our geotechnical experience in the
vicinity of the project, the following recommendations are presented for use in the project design and
construction. However, this report should be considered in its entirety. When applying the
recommendations for design, the background information, procedures used, findings and conclusions
should be considered. The recommended design consultation and construction monitoring by Moore
Twining are integral to the proper application of the recommendations. The Contractor should be
required to comply with the requirements and recommendations presented in this report.
Where the requirements of a governing agency, utility agency or product manufacturer differ from
the recommendations of this report, the more stringent recommendations should be applied to the
project.
8.1 General
8.1.1 The recommendations in this report are based on the design loads discussed
in the Anticipated Construction section ofthis report. Ifthe actual foundation
loads are higher, the recommendations in this report will need to be revised
to address the higher loading.
8.1 .2 Due to the high sulfate contents indicated by a number of the laboratory tests,
the soils at the site should not be treated with chemical additives such as
cement or lime.
8.1 .3 After the remediation for VOCs, it is anticipated that the near surface soils
above groundwater would remain significantly below optimum moisture
content for some time and would possess an increased potential for expansive
soil type heave when wetted in the future. In order to further evaluate the
depth of soil conditioning and compaction in this area, it is recommended that
a supplemental investigation, including test borings and laboratory tests, be
performed in this area following the cooling period after treatment is
completed. In addition, monitoring of potential surface settlement is
recommended in this area by setting and periodic monitoring of survey
benchmarks. The survey benchmarks should include temporarymonuments
to monitor deformation of the ground surface before, during, and after
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remediation activities. Moore Twining should be provided with the survey
data for review. The intent of the exploration and monitoring is to assess the
subsurface conditions prior to final grading. Soil movement should achieve
stabilization prior to final grading.
8.1.4 It is our understanding the current site owner will conduct some demolition
and soil removal work prior to turnover of the site to Shea Properties. All
excavations which are backfilled by the current site owner should be certified
as engineered fill by a civil or geotechnical engineer to Shea Properties prior
to turnover. Reports documenting the testing and inspection work relied
upon for the certification should also be provided.
8.1.5 A demolition plan should be developed to identiff existing improvements
which will require removal, such as pavements, foundations, concrete slabs,
utilities, subsurface components of the remediation system, etc.
8.1.6 A preconstruction meeting is recommended at least one week prior to the
start of construction between the owner, design team, contractor and Moore
Twining to discuss project requirements and scheduling.
8.1.7 All excavation and grading work should comply with the requirements of the
project environmental consultant and their associated reports including soil
and groundwater management plans.
8.1.8 Where wet, unstable soil conditions are experienced, and drying of the soils
in the bottom of the excavation is not adequate to achieve compaction and
stabilization, the bottom of the excavations may be stabilized by use of a
geotextile fabric and compacted aggregate base or crushed gravel. The
contractor should include in the bid the costs for stabilization of all wet,
unstable areas. It has been our experience that approximately 12 to l8 inches
of gravel encapsulated in a geotextile fabric, or a compacted aggregate base
underlain by a geotextile fabric can be used to achieve a stable bottom upon
which to place engineered fill. In addition, the overly moist soils excavated
will require drying prior to being used as engineered fill. Accordingly, the
Contractor should include provisions for addressing the wet soil conditions.
8.1.9 Due to the environmental conditions at the site (soil and groundwater
impacts), special design requirements, backfill, and/or trench cutoffs may be
necessary to address potential concerns with migration of contaminants in
utility trenches. Due to the granular nature of bedding and pipe zone backfill,
underground utilities can become paths for accelerating migration of
impacted groundwater. If this is a concern, a special backfill material with
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