February 4, 2014 J.N.: 2198.00 Mr. Joe Zink The Picerne Group

Transcription

February 4, 2014
J.N.: 2198.00
Mr. Joe Zink
The Picerne Group
30950 Rancho Viejo Road, Suite 200
San Juan Capistrano, CA 92675
Subject:
Preliminary Geotechnical Investigation, Proposed Multi-Family Residential
Development, 1100 Town and Country Road, Orange, California.
Dear Mr. Zink,
Albus-Keefe & Associates, Inc. is pleased to present to you our preliminary geotechnical
investigation report for the proposed multi-family residential development at the site. This report
presents the results of our review of the referenced literature and aerial photographs, subsurface
exploration, laboratory testing and engineering analyses. Conclusions and recommendations
relevant to design and construction of the proposed site development are also provided in this report.
We appreciate this opportunity to be of service to you. If you should have any questions regarding
the contents of this report, please do not hesitate to call our office.
Sincerely,
ALBUS-KEEFE & ASSOCIATES, INC.
David E. Albus
Principal Engineer
GE 2455
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TABLE OF CONTENTS
REPORT
1.0 INTRODUCTION..................................................................................................................... 1 1.1 PURPOSE AND SCOPE ........................................................................................................ 1 1.2 SITE LOCATION AND DESCRIPTION............................................................................... 1 1.3 PROPOSED DEVELOPMENT .............................................................................................. 3 2.0 INVESTIGATION .................................................................................................................... 3 2.1 RESEARCH ............................................................................................................................ 3 2.2 SUBSURFACE EXPLORATION .......................................................................................... 4 2.3 LABORATORY TESTING .................................................................................................... 4 3.0 SITE DEVELOPMENT BACKGROUND ............................................................................. 4 4.0 SUBSURFACE CONDITIONS ............................................................................................... 5 4.1 SOIL CONDITIONS ............................................................................................................... 5 4.2 GROUNDWATER .................................................................................................................. 6 4.3 FAULTING ............................................................................................................................. 7 5.0 ANALYSES ............................................................................................................................... 7 5.1 SEISMICITY ........................................................................................................................... 7 5.2 SETTLEMENT ....................................................................................................................... 7 5.3 STABILITY ANALYSES....................................................................................................... 8 6.0 CONCLUSIONS ....................................................................................................................... 8 6.1 FEASIBILITY OF PROPOSED DEVELOPMENT ............................................................... 8 6.2 GEOLOGIC HAZARDS ......................................................................................................... 9 6.2.1 Ground Rupture ................................................................................................................ 9 6.2.2 Ground Shaking ................................................................................................................ 9 6.2.3 Landsliding ....................................................................................................................... 9 6.2.4 Liquefaction ...................................................................................................................... 9 6.3 STATIC SETTLEMENT ...................................................................................................... 10 6.4 SLOPE STABILITY ............................................................................................................. 10 6.5 MATERIAL CHARACTERISTICS ..................................................................................... 10 6.6 SHRINKAGE AND SUBSIDENCE ..................................................................................... 11 6.7 SOIL EXPANSION............................................................................................................... 11 7.0 RECOMMENDATIONS ........................................................................................................ 11 7.1 EARTHWORK...................................................................................................................... 11 7.1.1 General Earthwork and Grading Specifications ............................................................. 11 7.1.2 Pre-Grade Meeting and Geotechnical Observation ........................................................ 11 7.1.3 Site Clearing.................................................................................................................... 12 7.1.4 Ground Preparation ......................................................................................................... 12 7.1.5 Temporary Excavations .................................................................................................. 12 7.1.6 Fill Placement ................................................................................................................. 13 7.1.7 Import Material ............................................................................................................... 13 7.2 SEISMIC DESIGN PARAMETERS .................................................................................... 13 7.3 PRELIMINARY CONVENTIONAL FOUNDATIONS ...................................................... 14 7.3.1 General ............................................................................................................................ 14 7.3.2 Soil Expansion ................................................................................................................ 14 7.3.3 Settlement ....................................................................................................................... 14 7.3.4 Allowable Bearing Value ................................................................................................ 14 ALBUS-KEEFE & ASSOCIATES, INC.
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TABLE OF CONTENTS (CONTINUED)
REPORT
7.3.5 Lateral Resistance ........................................................................................................... 14 7.3.6 Footing and Slab on Grade ............................................................................................. 15 7.3.7 Foundation Observations ................................................................................................ 15 7.4 RETAINING AND SCREENING WALLS.......................................................................... 16 7.4.1 General ............................................................................................................................ 16 7.4.2 Allowable Bearing Value and Lateral Resistance .......................................................... 16 7.4.3 Earth Pressures ................................................................................................................ 16 7.4.4 Drainage and Moisture-Proofing .................................................................................... 17 7.4.5 Footing Reinforcement ................................................................................................... 17 7.4.6 Footing Observations ...................................................................................................... 18 7.4.7 Wall Backfill ................................................................................................................... 18 7.5 EXTERIOR FLATWORK .................................................................................................... 18 7.6 CONCRETE MIX DESIGN.................................................................................................. 18 7.7 POST GRADING CONSIDERATIONS .............................................................................. 18 7.7.1 Site Drainage and Irrigation ............................................................................................ 18 7.7.2 Utility Trenches .............................................................................................................. 19 7.8 PRELIMINARY PAVEMENT DESIGN RECOMMENDATIONS .................................... 20 7.8.1 Subgrade Preparation ...................................................................................................... 20 7.8.2 Preliminary Pavement Designs ....................................................................................... 20 7.8.3 Pavement Materials ......................................................................................................... 20 7.9 PERCOLATION CHARACTERISTICS .............................................................................. 21 7.10 PLAN REVIEW AND CONSTRUCTION SERVICES ................................................... 21 8.0 LIMITATIONS ....................................................................................................................... 22 REFERENCES.................................................................................................................................. 23 FIGURES AND PLATES
Figure 1 - Site Location Map
Plate 1 – Site Plan
Plate 2 - Geotechnical Map
APPENDICES
APPENDIX A - Exploration Logs
Exploration Boring Logs - Plates A-1 through A-14
Exploration Trench Logs - Plates A-15 through A-22
APPENDIX B - Laboratory Testing Program
Table B - Summary of Laboratory Test Results
Plates B-1 through B-4 - Consolidation Test Plots
Plates B-5 through B-8 – Particle-Size Analyses
APPENDIX C - Exploration Logs & Laboratory Test Results by LeRoy Crandall and
Associates, January 30, 1986
APPENDIX D – Stability Analyses
Plates D-1 and D-2 – Plots of Analyses
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1.0
1.1
INTRODUCTION
PURPOSE AND SCOPE
The purposes of this investigation were to evaluate the subsurface soil conditions within the project
area, to evaluate their engineering characteristics, and to provide geotechnical conclusions and
recommendations relevant to design and construction of the proposed site development. The scope
of this investigation included the following:
1.2

Review of published geologic and seismic data for the area

Review of historical aerial photographs of the site and nearby vicinity

Review of previous geotechnical and environmental reports for the site and nearby vicinity
that were provided to us or located at the city of Orange

Exploratory drilling, trenching and sampling

Laboratory testing of selected soil samples

Engineering analyses of data obtained from our review, exploration and laboratory testing

Evaluation of site seismicity, liquefaction potential, bearing capacity and settlement potential

Preparation of this report
SITE LOCATION AND DESCRIPTION
The site is located at 1100 Town and Country Road, city of Orange, California. The site essentially
represents the undeveloped portion of the Orange Executive Tower development and is bordered by
Town and Country Road on the north, an office complex with a multi-story office building and a
detached parking structure to the east, a parking lot and an apartment complex to the south, and a
commercial retail center to the west. The location of the site and its relationship to the surrounding
areas is shown on the Site Location Map, Figure 1.
The site is a rectangular-shaped parcel that comprises approximately 2.76 acres of land. The site has
been extensively altered as a result of past construction activities and currently sits about 4 feet to as
much as 12 feet below the surrounding ground surface. Graded 1:1 (h:v) and flatter slopes generally
margin the site. A significantly deeper excavation up to 25 feet deep is also present within the north
central portion of the site. Vegetation at the site consists of a sparse growth of grass and weeds
across the site.
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SITE
© 2013 Google
N
SITE LOCATION MAP
Proposed Multi-Family Residential Development
1100 Town and Country Road
Orange, California
NOT TO SCALE
FIGURE 1
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Much of the site is currently vacant with exception of a small single-story office building with an
associated asphaltic concrete paved parking lot within the northeast margin of the site along Town
and Country Road. A Co-Generation (CoGen) facility that was used to generate electricity from
natural gas is also present along the southeastern margin of the site, along the adjoining parking
structure. We understand the facility supported the office complex to the east, but is no longer in
use. Other existing site improvements consist of chain-link fencing along the property lines. Some
“old” caissons were also encountered in the north-central portion of the site along the western
margin of the deep excavation. A large fill stockpile up to roughly 10 feet high is present in the
southern portions of the site. Smaller fill stockpiles with some construction debris are also present in
the northeasterly portion of the site as well as locally scattered throughout the property. No other
site improvements were observed during our field exploration.
1.3
PROPOSED DEVELOPMENT
Review of the referenced architectural plans indicates that the site will be developed with a podiumtype structure that will be 1- to 5-stories over 1 to 2 subterranean levels. Associated driveways,
decorative hardscape, landscaping, underground utilities, and a storm water infiltration system are
also anticipated. A layout of the ground floor level and ground site improvements is depicted on the
attached Site Plan - Plate 1.
No grading or structural plans were available at the time of this report. However, we anticipate that
some rough grading of the site will be required to achieve future surface configuration. The finish
floor of the lowest subterranean level is anticipated at an elevation of approximately 140 feet. The
podium level is anticipated to be at an elevation of approximately 160 feet. We expect the proposed
building above the podium deck will be wood-framed while the podium and lower levels will use
cast-in-place concrete walls and post-tension concrete decks. The bottom level is anticipated to
utilize a concrete slab on grade. We have assumed the maximum column load (D.L. + L.L.) for the
residential structure will be up to approximately 600 kips and the maximum wall load (D.L. + L.L.)
will be up to approximately 24 kips per linear foot.
2.0
2.1
INVESTIGATION
RESEARCH
We have completed a review of available geologic publications and maps for the site and nearby
vicinity (see references). We have also reviewed the referenced geotechnical reports prepared by
Irvine Soils Engineering Inc. (1979), LeRoy Crandall and Associates (1987), and Smith-Emery
Company (1987). In addition, we reviewed the environmental report prepared by Advanced
Environmental Concepts, Inc. for the subject site. Pertinent data from these sources were utilized in
developing some of the findings and conclusions presented herein.
The geotechnical investigation report prepared by LeRoy Crandall and Associates in 1987 was
prepared for the Tishman Executive Towers project and included the subject site as well as the
adjoining property to the east. At the time of their investigation, the site and the adjoining property
to the east were to be reconfigured for the development of two 16-story, sister structures and
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detached multi-level parking structures. Their investigation involved the excavation and logging of
9 exploratory borings and laboratory testing. Pertinent boring logs and laboratory test results from
their geotechnical report that we relied on for this investigation are included in Appendix C. The
reports by Irvine Soils Engineering and Smith-Emery pertain to the placement of fill soils within the
subject site and the east adjoining site.
2.2
SUBSURFACE EXPLORATION
Subsurface exploration for this investigation was conducted on August 1, 2013 and November 25,
2013. The exploration consisted of drilling five (5) exploratory borings and the excavation of fifteen
(15) exploratory trenches. The borings were drilled with a truck-mounted, hollow-stem-auger drill
rig (CME-95) to depths ranging from 51.5 to 56.5 feet below the existing ground surface (bgs).
Borings 4 and 5 were primarily used to perform percolation testing. The trenches were excavated to
depths ranging from about 4 to 14 feet utilizing a rubber-tired backhoe. Representatives of AlbusKeefe & Associates, Inc. logged the exploratory excavations. Visual and tactile identifications were
made of the materials encountered, and their descriptions are presented on the exploration logs in
Appendix A. The approximate locations of the exploratory excavations completed by this firm are
shown on the enclosed Geotechnical Map, Plate 2.
Bulk, relatively undisturbed and Standard Penetration Test (SPT) samples were obtained at selected
depths within the exploratory borings for subsequent laboratory testing. Relatively undisturbed
samples were obtained using a 3-inch O.D., 2.5-inch I.D., California split-spoon soil sampler lined
with brass rings. SPT samples were obtained from the borings using a standard, unlined SPT soil
sampler. During each sampling interval, the split-spoon sampler and SPT sampler were driven 12
and 18 inches, respectively, with successive drops of a 140-pound automatic hammer falling 30
inches. The number of blows required to advance the sampler was recorded for each six inches of
advancement. The total blow count for the lower 12 inches of advancement per soil sample is
recorded on the exploration logs. Samples were placed in sealed containers or plastic bags and
transported to our laboratory for analyses. The borings were backfilled with auger cuttings upon
completion of sampling.
2.3
LABORATORY TESTING
Selected samples of representative earth materials obtained from our borings excavated at the site
were tested in our soil laboratory. Tests consisted of in-situ moisture content and dry density, grainsize analysis, consolidation/collapse, and Atterberg limits. A description of laboratory testing and a
summary of the test results are presented in Appendix B and on the exploration logs provided in
Appendix A.
3.0
SITE DEVELOPMENT BACKGROUND
Based on our research, the subject site was initially utilized for agricultural purposes. During the
1930’s irrigated row crops covered the site. From the1940’s to the 1960’s the site was converted to
citrus groves. Sometime between 1960 and 1968, in association with area development and the
construction of the nearby 22 Freeway, the orange groves were demolished and a large excavation
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appeared in the area that encompassed the entirety of the subject project. Based on aerial
photographs and our subsurface work, we estimate this excavation extended approximately 10 feet
below the original ground surface to elevations of approximately 148 to 150 feet.
In June of 1979, the site and the east adjoining property were rough graded for construction of four
proposed tower structures as part of the Town & Country Residential Towers project. Two of the
tower structures were proposed within the subject site. A report of the rough grading was submitted
by Irvine Soils Engineering on July 2, 1979. Shortly after the rough grading, construction of spread
footings for structures ancillary to the towers were started but never completed. The locations of the
former tower building pads and overexcavation bottom elevations are indicated on the Geotechnical
Map, Plate 2.
In 1987, the site and the east adjoining parcel were reconfigured for development of two 16-story,
sister structures and detached multi-level parking structures as part of the Tishman Executive
Towers project. The spread footings constructed in 1979 appear to have been removed during this
time frame. Thus far, we have been unsuccessfully finding documentation of the rough grading
work that was performed within the subject site during this period. Based on our review of previous
documents, grading in 1987 was apparently completed under the observation of Smith-Emery
Company. A report prepared by Smith-Emery (1987) pertains to engineered fills placed within the
east adjoining parcel during this time frame. Fills placed in 1987 within the subject site appear to
have been placed contemporaneously with those reported by Smith-Emery. While construction of
the 16-story structure and associated parking structure was completed on the easterly adjacent
property, the sister building was never completed on the northerly half of the subject site. We
understand that several deep piles were constructed within the footprint of the uncompleted sister
building on the subject site. However, the actual number and dimensions of these piles are currently
unknown. Based on review of aerial photographs of the site, the geometric configuration of the site
has generally remained the same from 1987 until the time of our work.
4.0
4.1
SUBSURFACE CONDITIONS
SOIL CONDITIONS
Soil materials encountered at the site consists of compacted artificial fills materials associated with
previous construction activities overlying Quaternary alluvium. Stockpiled fills are also present on
the site. Descriptions of the earth materials encountered within the site are provided below.
The compacted artificial fills encountered within our exploratory excavations consist primarily of
yellow-brown to brown silty sands, sands and sandy silts that are generally fine-grained with some
scattered medium- to coarse-grained sand, gravel and trace cobbles. These materials are also
typically dry to moist and medium dense to dense or firm to stiff. However, in the upper few feet,
these materials are generally weathered and are loose or soft, porous, and locally contain roots.
Some small asphaltic concrete fragments, wood and rebar were also locally encountered in the
artificial fill. The thickness of artificial fills encountered within our exploratory excavations
generally varied from a few feet to as much as 15 feet. However, fills up to as much as 27 feet are
anticipated within the areas of the former building pads. Based on the finding from our
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investigation, portions of these fills were placed in 1979 under the observation and testing of Irvine
Soils Engineering (July 2, 1979) in association with the initial development of the Town & Country
Residential Towers project that was never completed. The fills placed in 1979 were reportedly
compacted to at least 95% of the maximum dry density (Irvine Soils Engineering, 1979). The
remainder of the fill was placed for the redevelopment of the Tishman Executive Towers project in
1987. Documentation concerning the fills placed in 1987 could not be found at the time of this
report but is believed to have been observed and tested by Smith-Emery Company.
A large fill stockpile up to roughly 10 feet high is present within the southerly portion of the site.
End-dumped fills up to roughly 4 feet in height are also present in the northeast margin of the site as
well as locally scattered throughout portions of the site. The stockpiled fills are largely comprised of
loose, yellow-brown to brown silty sands and soft sandy silts that are generally fine-grained and
contain various amounts of gravel and cobbles. Some minor construction debris, including small
chunks of concrete (less than 12 inches in diameter), were also observed in the end-dumped fills.
Alluvial soils underlie the entire site to the maximum depth explored. Generally, the upper 20 feet
of the alluvium is primarily comprised of brown and yellow-brown silty sand and sandy silt that is
fine-grained with trace gravels. These materials are typically damp, loose to medium dense or soft
to firm, and contain pores and local rootlets. Locally present within this upper sequence are friable
gravelly sands and sandy gravel layers and lenses that contain scattered cobbles and trace small
boulders. Between roughly 20 feet to 40 feet, the alluvium is generally coarser-grained and consist
primary of brown, yellow-brown and red-brown silty sands and sands with occasional clayey silt
layers and contain various amounts of gravel and cobbles typically up to 6 inches to 8 inches in
diameter with some up to as much as 10 inches in diameter. These materials are typically moist to
very moist, medium dense to dense, and locally friable. Below 40 feet, the alluvium generally
becomes finer grained and consists primarily of sandy silts with occasional interlayers of silty sands,
clayey sands, and clayey silts. This sequence is typically yellow to light yellow-brown, dark yellowbrown and brown in color, moist, very stiff to hard or medium dense to dense with some oxidation
staining and occasional carbon flakes and stringers.
A more detailed description of the soil materials encountered within the site is presented on the
exploration logs in Appendix A. The stratigraphic descriptions in the exploration logs represent the
predominant materials encountered and relatively thin, often discontinuous layers of different
material may occur within the major divisions.
Our exploration did not identify the presence of the spread footings reportedly constructed in 1979.
We did encounter a few caissons apparently constructed as part of the 1987 Tishman Executive
Towers project. The approximate locations of these caissons are depicted on the Geotechnical map,
Plate 2.
4.2
GROUNDWATER
Groundwater was not encountered to the maximum depth explored (56.5 feet bgs) during this
investigation nor encountered in the borings that were drilled by LeRoy Crandall and Associates in
1981 to the maximum depth explored (60.5 feet bgs). The referenced environmental report prepared
by Advanced Environmental Concepts, Inc. reported groundwater at 75 feet bgs in nearby irrigation
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wells. A review of the referenced Seismic Hazard Zone Report 011 indicates that historical high
groundwater level for the general site area is 40 feet or greater below the existing ground surface.
4.3
FAULTING
Geologic literature does not indicate the presence of active faulting within the site. The site does not
lie within an "Earthquake Fault Zone" as defined by the State of California in the Alquist-Priolo
Earthquake Fault Zoning Act. The closest known active fault is the Elsinore Fault Zone, Whittier
Section located approximately 11 miles northeast of the site.
5.0
5.1
ANALYSES
SEISMICITY
We have performed probabilistic seismic analyses utilizing computer program OpenSHA developed
by Field, E.H., T.H. Jordan, and C.A. Cornell (2003). OpenSHA is an open-source, Java-based
platform for conducting seismic hazard analysis. As an object-oriented framework, OpenSHA can
accommodate arbitrarily complex (e.g., physics based) earthquake rupture forecasts (ERFs), groundmotion models, and engineering-response models.
The computer program OpenSHA predicts the peak ground acceleration (PGA) having a 2 percent
chance of being exceeded in 50 years is approximately 0.49g when averages of three attenuation
relationships are used (Sadigh et al 1997, Abrahamson & Silva 1997, and Campbell & Bozorgnia
2003). The PGA having a 10 percent chance of being exceeded in 50 years is approximately 0.32g
when averages of three attenuation relationships are used (Sadigh et al 1997, Abrahamson & Silva
1997, and Campbell & Bozorgnia 2003).
5.2
SETTLEMENT
Analyses were performed to estimate the potential settlement of shallow spread footings. Results of
our subsurface work and laboratory testing were used to develop a characteristic soil profile for
analyses. Based on potential development schemes, foundations were assumed to be based on finish
floor elevations of 140, 150, and 160 feet. For these elevations, a variety of soil profiles are possible
across the site due to differences in topography and thicknesses of existing fill soils. We have
analyzed cases for each elevation in order to develop a possible range of values. For the purpose of
our analyses, we have assumed a typical bearing pressure of 4,000 pounds per square foot (psf), a
column load ranging from 200 to 600 kips, and a footing embedment of 2 feet below finish floor. A
summary of our analyses are provided in Table 5.1.
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TABLE 5.1
Summary of Settlement Analyses
Finish
Floor
Elevation
140’
140’
140’
150’
150’
150’
150’
160’
160’
5.3
Column
Load
(kips)
600
600
300
600
200
600
200
250
250
General Soil Condition
All native soils
7 ft. of new and existing fill over native soils
All native soils
All native soils
All native soils
5 ft. fill below footing
Estimated
Total
Settlement
(inches)
0.52
0.56
0.33
0.93
0.63
0.41
0.25
1.11
0.71
STABILITY ANALYSES
Analyses were performed to evaluate the stability of anticipated temporary slopes. The highest
temporary cut is anticipated to be approximately 20 feet and descend from the westerly property line.
The area beyond the property line will have an existing 1-story commercial building that is within
about 28 feet of the property line. We have assumed this building represents a blanket load of 300
psf. Soil strengths were based on results of direct shears provided in the referenced report by LeRoy
Crandall and Associates (1987). A summary of the assumed shear strengths is provided in Appendix
D, on Table D-1. Details of the computer program are provided in Appendix D
Two configurations were evaluated. The initial analysis used a 1.25 H to 1V slope descending a
total of 20 feet from the western property line. Our analysis indicates a factor of safety equal to
1.14. The second analysis used a 1.5H to 1V slope descending a total of 20 feet from the western
property line. Our analysis indicates a factor of safety equal to 1.30. Plots of the analyses are
provided in Appendix D as Plates D-1 and D-2.
6.0
6.1
CONCLUSIONS
FEASIBILITY OF PROPOSED DEVELOPMENT
From a geotechnical point of view, the proposed site development is considered feasible provided
the recommendations presented in this report are incorporated into the design and construction of the
project. Furthermore, it is also our opinion that the proposed development will not adversely impact
the stability of adjoining properties. Key issues that could have significant fiscal impacts on the
geotechnical aspects of the proposed site development are discussed in the following sections of this
report.
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GEOLOGIC HAZARDS
6.2.1
Ground Rupture
No active faults are known to project through the site nor does the site lie within the bounds of an
"Earthquake Fault Zone" as defined by the State of California in the Alquist-Priolo Earthquake Fault
Zoning Act. As such, the potential for ground rupture due to a fault displacement beneath the site is
considered very low.
6.2.2 Ground Shaking
The site is situated in a seismically active area that has historically been affected by generally
moderate to occasionally high levels of ground motion. The site lies in relative close proximity to
several active faults; therefore, during the life of the proposed improvements, the property will
probably experience similar moderate to occasionally high ground shaking from these fault zones, as
well as some background shaking from other seismically active areas of the Southern California
region. Design and construction in accordance with the current California Building Code (CBC)
requirements is anticipated to address the issues related to potential ground shaking.
6.2.3 Landsliding
The site is not located within an area identified by the California Geologic Survey (CGS) as having
potential for seismic slope instability. Geologic hazards associated with landsliding are not
anticipated at the sites.
6.2.4 Liquefaction
Engineering research of soil liquefaction potential (Youd, et al., 2001) indicates that generally three
basic factors must exist concurrently in order for liquefaction to occur. These factors include:



A source of ground shaking, such as an earthquake, capable of generating soil mass
distortions.
A relatively loose silty and/or sandy soil.
A relative shallow groundwater table (within approximately 50 feet below ground surface) or
completely saturated soil conditions that will allow positive pore pressure generation.
The liquefaction susceptibility of the onsite soils was evaluated by analyzing the potential concurrent
occurrence of the above-mentioned three basic factors. The liquefaction evaluation for the site was
completed under the guidance of Special Publication 117A: Guidelines for Evaluating and
Mitigating Seismic Hazards in California (CDMG, 2008).
Historical high groundwater is anticipated at a depth greater than 40 feet below the site. Soils
located below a depth of 40 feet are anticipated to consist of either dense granular soils or finegrained soils that are not susceptible to liquefaction. A portion of the southern half of the site is
located within a mapped California Geologic Survey liquefaction hazard zone. However, our site
investigation indicates the potential for liquefaction to occur beneath the site is considered to be low.
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STATIC SETTLEMENT
Based on our preliminary settlement analyses, total settlements are generally anticipated to be less
than 1 inch for spread footings founded upon the anticipated conditions at anticipated grades.
Associated differential settlement could be on the order of ¾-inches over 30 feet. The actual total
and differential settlements will be dependent upon the final foundation configuration since a
significant variation in foundation loads and subsurface conditions could be encountered. Where the
differential settlement is estimated to exceed ½-inch over 30 feet, the existing native soils could be
removed and replaced as compacted fill to a depth of about 5 feet below footings in order to reduce
the differential to ½-inch over 30 feet or less.
6.4
SLOPE STABILITY
Excavation for the subterranean portion of the building will require cuts up to approximately 20 feet
below the adjacent grades. Results of our analyses indicate that a temporary slope cut at a gradient
of 1.5H to 1V will provide a calculated factor of safety greater than 1.25 provided there is no
surcharge by adjacent buildings within about 28 feet. A value of 1.25 or greater is generally
considered suitable for temporary conditions.
An existing parking structure is located near the southeastern property corner. The building is
located about 11 feet from the property line and the proposed building will be located about 3 feet
from the property line. We anticipate the proposed development will require a temporary cut of
about 10 feet deep along this building. The details of the existing structure are not known at this
time such as what type of foundation is used or the finish floor elevation of the lowest level. We
anticipate this structure has at least one level below grade and/or may be supported by pile
foundations. If so, we anticipate that an open 1H to 1V cut will be feasible in this area in order to
construct the proposed building. Such a cut would extend beyond the building limits by about 7 to 8
feet and therefore require permission from the adjacent owner. Once details of the existing structure
can be obtained, additional evaluate of the requirements for constructing the subterranean level will
be required.
6.5
MATERIAL CHARACTERISTICS
Soils located above an elevation of 130 feet are anticipated to be relatively easy to excavate with
conventional heavy earthmoving equipment. At greater depths, the earth materials become very
dense and include abundant cobbles to about 6 inches in diameter with a few reaching 12 inches in
diameter. These materials can generally be removed by a backhoe with some difficulty and with
little difficulty by an excavator. These materials would also tend to slow the progress of drilling
equipment.
Materials anticipated to be excavated have in-place moisture contents that are near or significantly
below optimum moisture content. Therefore, grading will generally require the addition of water to
prepare the existing soils for use as compacted fill. Site materials are not anticipated to require
unusual effort to bring them to appropriate moisture contents.
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SHRINKAGE AND SUBSIDENCE
Volumetric changes in earth quantities will occur when excavated onsite soil materials are replaced
as properly compacted fill. We estimate the existing stockpiled fills may shrink approximately 15 to
20 percent and alluvium may shrink approximately 5 to 10 percent. The existing compacted fill
materials will have a negligible impact on shrinkage. Subsidence from scarification and
recompaction of exposed subgrade surfaces is estimated to be negligible. The estimates of shrinkage
and subsidence are intended as an aid for project engineers in determining earthwork quantities.
However, these estimates should be used with some caution since they are not absolute values.
Contingencies should be made for balancing earthwork quantities based on actual shrinkage and
subsidence that occur during the grading process.
6.7
SOIL EXPANSION
Soils present above an elevation of 115 feet are generally anticipated to possess Very Low to Low
expansion potentials. Some soils located below an elevation of 115 feet are anticipated to exhibit
Medium to High expansion potentials. If finish floors are set at or below an elevation of 130 feet,
then the expansive nature of soils with Medium to High expansion potential could influence design
and construction of site development. Additional testing for soil expansion will be required
subsequent to rough grading and prior to construction of foundations and other concrete flatwork to
confirm these conditions.
7.0
7.1
RECOMMENDATIONS
EARTHWORK
7.1.1 General Earthwork and Grading Specifications
All earthwork and grading should be performed in accordance with applicable requirements of
Cal/OSHA, applicable specifications of the Grading Codes of City of Orange, California, in addition
to recommendations presented herein.
7.1.2 Pre-Grade Meeting and Geotechnical Observation
Prior to commencement of grading, we recommend a meeting be held between the developer, City
inspector, grading contractor, civil engineer, structural engineer, and geotechnical consultant to
discuss the proposed grading and logistics. We also recommend that a geotechnical consultant be
retained to provide soil engineering and engineering geologic services during site grading and
foundation construction. This is to observe compliance with the design specifications and
recommendations, and to allow design changes in the event that subsurface conditions differ from
those anticipated. If conditions are encountered that appear to be different than those indicated in
this report, the project geotechnical consultant should be notified immediately. Design and
construction revisions may be required.
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7.1.3 Site Clearing
All existing site improvements, vegetation and other deleterious materials should be removed from
the areas to be developed. If a conventional foundation system will be used to support the proposed
structure, the existing piles installed at the site should be demolished to at least 5 feet below the
bottom of the proposed footings. The project geotechnical consultant should be notified at the
appropriate times to provide observation services during clearing operations to verify compliance
with the above recommendations. Voids created by clearing should be left open for observation by
the geotechnical consultant. Should any unusual soil conditions or subsurface structures be
encountered during site clearing or grading that are not described or anticipated herein, these
conditions should be brought to the immediate attention of the project geotechnical consultant for
corrective recommendations.
7.1.4 Ground Preparation
All existing stockpiled artificial fill soils and the upper 1 to 2 feet of compacted fill or alluvium are
not suitable to support the proposed site improvements and should be removed and replaced with
engineered compacted fill. Within nearly the entire limits of the building, we anticipate proposed
cuts will exceed these depths. The exception is anticipated to occur along a narrow strip of the
building at the southern edge of the building where the building is anticipated to be founded near an
elevation of 160 feet. We also anticipate this portion of the structure will require the existing soils
be over-excavated to 5 feet below bottom of footings. The over-excavation should extend at least 5
feet beyond the edges of footings. Additional footings may also require over-excavation based on
final review of the foundation plans. Additional recommendations for over-excavation should be
provided upon review of the foundation plans.
The actual limits and depths of removals should be determined in the field during grading based on
observations by the geotechnical consultant, the proposed foundation system and actual foundation
loads.
Following removals and over-excavation, the exposed grade should first be scarified to a depth of 6
inches; moisture conditioned to slightly over optimum moisture content, and then re-compacted to at
least 90 percent of the laboratory standard.
The grading contractor should take appropriate measures when excavating adjacent existing
improvements to avoid disturbing or compromising support of existing structures/improvements.
7.1.5 Temporary Excavations
Temporary construction slopes in site soils may be cut vertically up to a height of 4 feet provided
that no friable sands or surcharging (such as adjacent buildings) of the excavations are present.
Temporary slopes over 4 feet but not exceeding 10 feet that are not surcharged should be laid back at
a maximum gradient of 1:1 (H:V) or properly shored. Temporary slopes over 10 feet but not
exceeding 20 feet that are not surcharged should be laid back at a maximum gradient of 1.5:1 (H:V)
or properly shored. Excavations should not be left open for prolonged periods of time. The project
geotechnical consultant should observe all temporary cuts to confirm anticipated conditions and to
provide alternate recommendations if conditions dictate.
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Where temporary excavations cannot accommodate a layback or where surcharging occurs, slot
cutting, shoring, underpinning, or other methods should be used. Specific recommendations for
these options should be provided by the geotechnical consultant after specific design plans have been
developed.
7.1.6
Fill Placement
Earth materials excavated from the site may be used as fill provided they are free of deleterious
materials and particles greater than 4 inches in maximum dimension (oversized materials). Asphalt
concrete and concrete debris generated during site demolition can likely be reduced to no more than
4 inches in maximum dimensions and incorporated into fill soils during earthwork operations. Fill
should be placed in lifts no greater than 8 inches in loose thickness, moisture conditioned to slightly
over the optimum moisture content, then compacted in place to at least 90 percent of the laboratory
standard. The laboratory standard for maximum dry density and optimum moisture content for each
soil type used should be determined in accordance with ASTM D1557-07. Each lift should be
treated in a similar manner. Subsequent lifts should not be placed until the project geotechnical
consultants have approved the preceding lift.
7.1.7 Import Material
If imported soils are required to bring the site to proposed grades, imported soils should have a
maximum particle size of 4 inches and have an expansion index (EI) less than 21. Potential import
soils should be sampled by the geotechnical consultant at the source, if possible, tested for expansion
potential, soluble sulfate content and maximum dry density, and approved by the geotechnical
consultant prior to being used.
7.2
SEISMIC DESIGN PARAMETERS
For design of the project in accordance with Chapter 16 of the 2013 CBC, the following table
presents the seismic design factors:
TABLE 7.1
2013 CBC Seismic Design Parameters
Parameter
Site Class
Mapped MCER Spectral Response Acceleration, short periods, SS
Mapped MCER Spectral Response Acceleration, at 1-sec. period, S1
Site Coefficient, Fa
Site Coefficient, Fv
Adjusted MCER Spectral Response Acceleration, short periods, SMS
Adjusted MCER Spectral Response Acceleration, at 1-sec. period, SM1
Design Spectral Response Acceleration, short periods, SDS
Design Spectral Response Acceleration, at 1-sec. period, SD1
MCER = Risk-Targeted Maximum Considered Earthquake
Value
D
1.480
0.541
1.0
1.5
1.480
0.811
0.987
0.541
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7.3
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PRELIMINARY CONVENTIONAL FOUNDATIONS
7.3.1 General
The following design parameters are provided to assist the project structural engineer to design the
conventional foundations of the proposed structures at the site. These design parameters are based
on typical site materials encountered during subsurface exploration and are provided for preliminary
design and estimating purposes. The project geotechnical consultant should provide final design
parameters following observation and testing of site materials during grading. Depending on actual
materials encountered during site grading and foundation loads, the design parameters presented
herein may require modification.
7.3.2 Soil Expansion
The recommendations presented herein for foundations are based on soils with a Very Low to Low
expansion potential. Following site grading, additional testing of site soils should be performed by
the project geotechnical consultant to confirm the existing expansion potential for the site. If site
soils with significantly different expansion potentials are encountered, the recommendations
contained herein may require modification.
7.3.3 Settlement
The proposed foundation systems should be designed to tolerate a total and differential settlement of
up to 1 inch and ½-inch over 30 feet, respectively.
7.3.4 Allowable Bearing Value
Provided site grading is performed in accordance with the recommendations provided by the project
geotechnical consultant, a bearing value of 2,000 psf may be used for continuous and pad footings
having a minimum width of 12 inches and 24 inches, respectively, and founded at a minimum depth
of 12 inches below the lowest adjacent grade. The above bearing value may be increased by 300 psf
and 750 psf for each additional foot in width and depth, respectively, up to a maximum value of
4,000 psf. The recommended allowable bearing value includes both dead and live loads, and may be
increased by one-third for wind and seismic forces.
7.3.5 Lateral Resistance
Provided site grading is performed in accordance with the recommendations provided by the project
geotechnical consultant, a passive earth pressure of 200 pounds per square foot per foot of depth up
to a maximum value of 1500 pounds per square foot may be used to determine lateral bearing for
footings. This value may be increased by one-third when designing for wind and seismic forces. A
coefficient of friction of 0.37 times the dead load forces may also be used between concrete and the
supporting soils to determine lateral sliding resistance. No increase in the coefficient of friction
should be used when designing for wind and seismic forces.
The above values are based on foundations placed directly against compacted fill. In the case where
footing sides are formed, all backfill against the foundations should be compacted to at least 90
percent of the laboratory standard.
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Footing and Slab on Grade
Exterior continuous footings should be founded at a minimum depth of 18 inches below the lowest
adjacent grade. Interior bearing wall footings should be founded at a minimum depth of 12 inches
below the lowest adjacent finish grade. All continuous footings should be reinforced with a
minimum of two No. 4 bars, one top and one bottom. The structural engineer may require different
reinforcement and should dictate if greater than the recommendations presented herein.
Exterior isolated pad footings should be a minimum of 24 inches square and founded at a minimum
depth of 18 inches below the lowest adjacent final grade. Interior isolated pad footings should be a
minimum of 24 inches square and founded at a minimum depth of 12 inches below the lowest
adjacent finish grade.
Interior concrete slabs constructed on grade should be a minimum 4 inches thick and should be
reinforced with No. 3 bars spaced 18 inches each way or with 6” by 6”, W4 by W4 welded wire
mesh. Care should be taken to ensure the placement of reinforcement at mid-slab height. The
structural engineer may recommend a greater slab thickness and reinforcement based on proposed
use and loading conditions and such recommendations should govern if greater than the
recommendations presented herein.
Concrete floor slabs in areas to receive carpet, tile, or other moisture sensitive coverings should be
underlain with a moisture vapor barrier such as 10-mil Visqueen, or equal. The membrane should be
properly lapped, sealed, and placed in the middle of 4 inches of sand having a sand equivalent (SE)
of 30 or greater. This vapor barrier system is anticipated to be suitable for most flooring finishes
that can accommodate some vapor emissions. However, this system may emit more than 4 pounds
of water per 1000 sq. ft. and therefore, may not be suitable for all flooring finishes. Additional steps
should be taken if such vapor emission levels are too high for anticipated flooring finishes.
Special consideration should be given to slabs in areas to receive ceramic tile or other rigid, cracksensitive floor coverings. Design and construction of such areas should mitigate hairline cracking as
recommended by the structural engineer.
Block-outs should be provided around columns to permit relative movement and mitigate distress to
the slabs due to differential settlement that will occur between column footings and adjacent floor
subgrade soils, as loads are applied. In lieu of block-out, the slabs may be saw cut at each of the four
corners of the columns.
Prior to placing concrete, subgrade soils below slab-on-grade areas should be thoroughly moistened
to at least 100 percent of optimum moisture content to a depth of 12 inches.
7.3.7
Foundation Observations
All foundation excavation should be observed by the project geotechnical consultant to verify that
they have been excavated into competent bearing soils and to the minimum embedment
recommended above. These observations should be performed prior to placement of forms or
reinforcement. The excavations should be trimmed neat, level and square. Loose, sloughed or
moisture-softened materials and debris should be removed prior to placing concrete.
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7.4
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RETAINING AND SCREENING WALLS
7.4.1 General
The following recommendations are provided for preliminary design purpose. Final retaining wall
designs specific to the site development should be provided to us for review once completed.
7.4.2 Allowable Bearing Value and Lateral Resistance
Retaining walls may utilize the bearing capacities and lateral resistance values provided in Sections
7.3.4 and 7.3.5. The passive pressure used for lateral bearing should be reduced by 50% for walls
that have a descending slope below the face of the wall.
The above values are based on footings placed directly against properly compacted fill. In the case
where footing sides are formed, all backfill against the footings should be compacted to at least 90
percent of the laboratory standard.
7.4.3
Earth Pressures
Static and seismic earth pressures for level backfill and 2:1 (H:V) backfill conditions are provided in the
following table. Seismic earth pressures provided herein are based on the method provided by Seed
& Whitman (1970) using a peak ground acceleration (PGA) of 0.37g. This acceleration is based on
40 percent of the short period of design spectral response acceleration determined for the site. Per
the 2013 CBC, seismic earth pressures need not be applied to retaining walls that retain 6 feet or
less. The values provided in the following table are based on drained backfill conditions and do not
consider hydrostatic pressure. Furthermore, retaining walls should be designed to support adjacent
surcharge loads imposed by other nearby footings or traffic loads in addition to the earth pressure.
TABLE 7.2
EARTH PRESSURES
Pressure Diagram
Static
Component
Seismic
Component
Total
Force
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Pressure Values
Walls Up to 10 Feet in Height
Backfill Condition
Level
2H:1V Slope
Restrained Condition
Level Backfill
A
37H
65.5H
62.5H
B
C
11.5H
24.5H
11.5H
38.5H
20.5H
41.5H
Value
Note:
H is in feet and resulting pressure is in psf. Design may utilize either the sum of the static component and
the seismic component force diagrams or the total force diagram above. SEAOSC has suggested using a
load factor of 1.7 for the static component and 1.0 for the seismic component. The actual load factors
should be determined by the structural engineer.
7.4.4 Drainage and Moisture-Proofing
Exterior retaining walls retaining more than 3 feet of soils should be constructed with a perforated
pipe and gravel subdrain to prevent entrapment of water in the backfill. The perforated pipe should
consist of 4-inch-diameter, ABS SDR-35 or PVC Schedule 40 with the perforations laid down. The
pipe should be embedded in ¾- to 1½-inch open-graded gravel wrapped in filter fabric. The gravel
should be at least one foot wide and extend at least one foot up the wall above the footing and
drainage outlet. Drainage gravel and piping should not be placed below outlets and weepholes.
Filter fabric should consist of Mirafi 140N, or equal. Outlet pipes should be directed to positive
drainage devices.
The use of weepholes may be considered in locations where aesthetic issues from potential nuisance
water are not a concern. Weepholes should be 2 inches in diameter and provided at least every 6 feet
on center. Where weepholes are used, perforated pipe may be omitted from the gravel subdrain.
Exterior retaining walls supporting backfill should also be coated with a moisture-proofing
compound or covered with such material to inhibit infiltration of moisture through the walls.
Moisture-proofing material should cover any portion of the back of wall that will be in contact with soil
and should lap over onto the top of footing. A drainage blanket such as Mirafi Miradrain should be
provided between the soil and the moisture-proofing materials. The drainage blanket should extend
from the top of the gravel to within about 12 inches of finish grade. The top of footing should be
finished smooth with a trowel to inhibit the infiltration of water through the wall. The project structural
engineer should provide specific recommendations for moisture-proofing, water stops, and joint details.
7.4.5 Footing Reinforcement
All continuous footings should be reinforced with a minimum of two No. 4 bars. The structural
engineer may require different reinforcement and should dictate if greater than the recommendations
provided herein. Where recommended removals are limited due to space restrictions, greater
reinforcement may be recommended. Specific recommendations should be provided by the
geotechnical consultant during grading based on as-built conditions exposed in the field.
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Footing Observations
Footing excavations should be observed by the project geotechnical consultant to verify that they
have been excavated into competent bearing soils and to the minimum embedment recommended
herein. These observations should be performed prior to placement of forms or reinforcement. The
excavations should be trimmed neat, level and square. Loose, sloughed or moisture-softened
materials and debris should be removed prior to placing concrete.
7.4.7
Wall Backfill
The project geotechnical consultant should approve the backfill used for retaining walls and the
backfill should have a Very Low to Low expansion potential. Wall backfill should be moistureconditioned to slightly over the optimum moisture content; placed in lifts no greater than 12 inches
in thickness, and then mechanically compacted with appropriate equipment to at least 90 percent of
the laboratory standard. Hand-operated compaction equipment should be used to compact the
backfill placed immediately adjacent the wall to avoid damage to the wall. Flooding or jetting of
backfill material is not recommended.
7.5
EXTERIOR FLATWORK
Exterior flatwork should be a minimum 4 inches thick. Cold joints or saw cuts should be provided at
least every 10 feet in each direction. Special jointing detail should be provided in areas of blockouts, notches, or other irregularities to avoid cracking at points of high stress. Subgrade soils below
flatwork should be thoroughly moistened to a moisture content of at least 110 percent of the
optimum moisture content to a depth of 12 inches. Moistening should be accomplished by lightly
spraying the area over a period of a few days just prior to pouring concrete. Drainage from flatwork
areas should be directed to local area drains or other appropriate collection devices designed to carry
runoff water to the street or other approved drainage structures. The geotechnical consultant should
observe and verify the density and moisture content of subgrade soils prior to pouring concrete to
verify the recommended pre-moistening recommendations have been met.
7.6
CONCRETE MIX DESIGN
Laboratory testing of existing near-surface soils for soluble sulfate content indicates soluble sulfate
concentration less than 0.10%. The procedures provided in ACI 318, Section 4.3, Table 4.3.1 for
negligible sulfate exposures are anticipated to govern concrete design. Additional sampling and
testing following site grading will be required to confirm this assumption.
7.7
POST GRADING CONSIDERATIONS
7.7.1 Site Drainage and Irrigation
The ground immediately adjacent to foundations should be provided with positive drainage away
from the structures in accordance with 2010 CBC, Section 1804.3. However, the slope of ground
away from the foundations may be reduced from 5% to 2% minimum based on climatic and soil
conditions present at the site. No rain or excess water should be allowed to pond against structures
such as walls, foundations, flatwork, etc.
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Excessive irrigation water can be detrimental to the performance of the proposed site development.
Water applied in excess of the needs of vegetation will tend to percolate into the ground. Such
percolation can lead to nuisance seepage and shallow perched groundwater. Seepage can form on
slope faces, on the faces of retaining walls, in streets, or other low-lying areas. These conditions
could lead to adverse effects such as the formation of stagnant water that breeds insects, distress or
damage of trees, surface erosion, slope instability, discoloration and salt buildup on wall faces, and
premature failure of pavement. Excessive watering can also lead to elevated vapor emissions within
buildings that can damage flooring finishes or lead to mold growth inside the buildings.
Key factors that can help mitigate the potential for adverse effects of overwatering include the
judicious use of water for irrigation, use of irrigation systems that are appropriate for the type of
vegetation and geometric configuration of the planted area, the use of soil amendments to enhance
moisture retention, use of low-water demand vegetation, regular use of appropriate fertilizers, and
seasonal adjustments of irrigation systems to match the water requirements of vegetation. Specific
recommendations should be provided by a landscape architect or other knowledgeable professional.
7.7.2 Utility Trenches
Trench excavations should be constructed in accordance with the recommendations contained in
Section 7.1.5 of this report. Trench excavations must also conform to the requirements of Cal/
OSHA.
Trench backfill materials and compaction criteria should conform to the requirements of the local
municipalities. As a minimum, utility trench backfill should be compacted to at least 90 percent of
the laboratory standard. Materials placed within the pipe zone (6 inches below and 12 inches above
the pipe) should consist of particles no greater than ¾ inches and have a SE of at least 30. The
materials within the pipe zone should be consolidated by flooding or jetting. Above the pipe zone
(>1 foot above pipe), the backfill may consist of general fill materials. Trench backfill should be
brought to uniform moisture, slightly over optimum, placed in lifts no greater than 12 inches in
thickness, and then mechanically compacted with appropriate equipment to at least 90 percent of the
laboratory standard. For trenches with sloped walls, backfill material should be placed in lifts no
greater than 8 inches in loose thickness, and then compacted by rolling with a sheepsfoot roller or
similar equipment. The project geotechnical consultant should perform density testing along with
probing to verify that adequate compaction has been achieved.
Within shallow trenches (less than 18 inches deep) where pipes may be damaged by heavy
compaction equipment, imported clean sand having a SE of 30 or greater may be utilized. The sand
should be placed in the trench, thoroughly watered, and then compacted with a vibratory compactor.
For utility trenches located below a 1:1 (H:V) plane projecting downward from the outside edge of
the adjacent footing base or crossing footing trenches, concrete or slurry should be used as trench
backfill.
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7.8
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PRELIMINARY PAVEMENT DESIGN RECOMMENDATIONS
7.8.1 Subgrade Preparation
Prior to placement of pavement elements, the upper 12 inches of subgrade soils should be moistureconditioned to at least 100 percent of the optimum moisture content and compacted to at least 90
percent of the laboratory standard. Where concrete paving will be constructed over soils, the upper
12 inches of pavement subgrade should be compacted to at least 95 percent of the laboratory
standard. Areas observed to pump or yield under vehicle traffic should be removed and replaced
with firm and unyielding compacted soil or aggregate base materials.
7.8.2 Preliminary Pavement Designs
Based on the soil conditions present at the site and estimated traffic indices, preliminary pavement
sections are provided in the table below. A preliminary “R-value” of 20 was used for the nearsurface soil in this preliminary pavement design. The sections provided below are for planning
purposes only and should be re-evaluated subsequent to site grading. Final pavement sections
should be based on actual R-value testing of in-place soils and analysis of anticipated traffic.
TABLE 7.3
PRELIMINARY PAVEMENT STRUCTURAL SECTIONS
Location
Driveway
Assumed
T.I.
6.0
A.C.
(inches)
P.C.C.
(inches)
A.B.
(inches)
3.0
-
10.0
-
7.0
-
A.C. = Asphalt Concrete, P.C.C. = Portland Cement Concrete, A.B. = Aggregate Base
7.8.3 Pavement Materials
Aggregate base should be moisture conditioned to slightly over the optimum moisture content,
placed in lifts no greater than 6 inches in thickness, then compacted to at least 95 percent of the
laboratory standard (ASTM D 1557-07). Aggregate base materials should be Class 2 Aggregate
Base conforming to Section 26-1 of the 2010 Edition of the Caltrans Standard Specifications,
Crushed Aggregate Base conforming to Section 200-2.2 of the 2012 Edition of the Standard
Specifications for Public Works Construction (Greenbook) or Crushed Miscellaneous Base
conforming to Section 200-2.4 of the Greenbook.
Paving asphalt should be PG 64-10. Asphaltic concrete materials should conform to Section 203-6
of the Greenbook and construction should conform to Section 302 of the Greenbook.
Portland cement concrete used to construct concrete paving should conform to Section 201 of the
Greenbook and should have a minimum compressive strength of 3500 pounds per square inch (psi)
at 28 days. Reinforcement and jointing of concrete pavement sections should be designed according
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to the minimum recommendations provided by the Portland Cement Association (PCA). For rigid
pavement, transverse and longitudinal contraction joints should be provided at spacing no greater
than 15 feet. Score joints may be constructed by saw cutting to a depth of ¼ of the slab thickness.
Expansion/cold joints may be used in lieu of score joints. Such joints should be properly sealed and
provided with a key or dowels. Where traffic will traverse over edges of concrete paving (not
including joints), the edges should be thickened by 20% of the design thickness toward the edge over
a horizontal distance of 5 feet.
7.9
PERCOLATION CHARACTERISTICS
Recommendations for design and construction of the proposed storm water infiltration system will
be provided in a separate report.
7.10 PLAN REVIEW AND CONSTRUCTION SERVICES
We recommend Albus-Keefe & Associates, Inc. be engaged to review any future development plans,
including civil plans (grading plans), structural plans (foundation plans), and proposed structural
loads, prior to construction. This is to verify that the assumptions of this report are valid and that the
preliminary conclusions and recommendations contained in this report have been properly
interpreted and are incorporated into the project plans and specifications. If we are not provided the
opportunity to review these documents, we take no responsibility for misinterpretation of our
preliminary conclusions and recommendations.
We recommend that a geotechnical consultant be retained to provide soil engineering services during
construction of the project. These services are to observe compliance with the design, specifications
or recommendations, and to allow design changes in the event that subsurface conditions differ from
those anticipated prior to the start of construction.
If the project plans change significantly from the assumed development described herein, the project
geotechnical consultant should review our preliminary design recommendations and their
applicability to the revised construction. If conditions are encountered during construction that
appear to be different than those indicated in this report or subsequent design reports, the project
geotechnical consultant should be notified immediately. Design and construction revisions may be
required.
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8.0
LIMITATIONS
This report is based on the proposed development and geotechnical data as described herein. The
materials encountered on the project site, described in other literature, and utilized for this
investigation are believed representative of the total project area, and the conclusions and
recommendations contained in this report are presented on that basis. However, soil materials can
vary in characteristics between points of exploration, both laterally and vertically, and those
variations could affect the conclusions and recommendations contained herein. As such, observation
and testing by a geotechnical consultant during the grading and construction phases of the project are
essential to confirming the basis of this report.
This report has been prepared consistent with that level of care being provided by other professionals
providing similar services at the same locale and time period. The contents of this report are
professional opinions and as such, are not to be considered a guaranty or warranty.
This report should be reviewed and updated after a period of one year or if the site ownership or
project concept changes from that described herein.
This report has been prepared for the exclusive use of The Picerne Group and its project
consultants in the planning and design of the proposed development. This report has not been
prepared for use by parties or projects other than those named or described herein. This report may
not contain sufficient information for other parties or other purposes.
This report is subject to review by the controlling governmental agency.
Respectfully submitted,
ALBUS-KEEFE & ASSOCIATES, INC
David E. Albus
Principal Engineer
GE 2455
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REFERENCES
Publications
Abrahamson, N. A., and W. J. Silva (1997), Empirical Response Spectral Attenuation Relations for
Shallow Crustal Earthquakes, Seismological Research Letters, 68(1), 94-127.
California Geologic Survey, Special Publication 117A, Guidelines for Evaluating and Mitigating
Seismic Hazards in California, 2008.
Campbell, K. W. and Y. Bozorgnia (2003), Updated near-source ground motion (attenuation)
relations for the horizontal and vertical components of peak ground acceleration and acceleration
response spectra, Bulletin of the Seismological Society of America, 93(1), 314 -331.
CDMG, “Seismic Hazard Zone Report for the Orange 7.5-Minute Quadrangle, Orange County,
California,” Seismic Hazard Zone Report 011, 1997.
CDMG, “Seismic Hazard Zones, Orange Quadrangle,” dated April 15, 1998.
Field, E.H., T.H. Jordan, and C.A. Cornell, OpenSHA: A Developing Community-Modeling
Environment for Seismic Hazard Analysis, Seismological Research Letters, 74, no. 4, p. 406-419,
(2003).
Sadigh, K., Chang, C.Y., Egan, J.A., Makdisi, F., and Youngs, R.R. “Attenuation Relationships for
Shallow Crustal Earthquakes Based on California Strong Motion Data,” Seismological Research
Letters, Vol. 68, No.1, January/February 1997.
Seed, H.B., Idriss, I.M., “Ground Motions and Soil Liquefaction During Earthquakes,” published by
the EERI, dated December 1982.
Youd, T.L., Idriss, I.M., Andrus, R.D., Arango, I., Castro, G., Christian, J., Dobry, R., Finn, W.D.L.,
Harder, L.F., Hynes, M.E., Ishihara, K., Koester, J.P., Liao, S.S.C., Marcuson, W.F., Martin, G.R.,
Mitchell, J.K., Moriwaki, Y., Power, M.S., Robertson, P.K., Seed, R.B., and Stokoe, K.H.,
“Liquefaction Resistance of Soils: Summary Report from the 1996 NCEER and 1998 NCEER/NSF
Workshops on Evaluation of Liquefaction Resistance of Soils,” Journal of Geotechnical and
Geoenvironmental Engineering, October, 2001.
Reports
Advanced Environmental Concepts Inc., Phase-1 Environmental Site Assessment for 1100 Town
and Country Road, Approximate 2.76–acre undeveloped Parcel - Portion of Orange Executive
Acres, Bordered on the North by Town and Country Road, County of Orange, California, dated
August 2013.
The Picerne Group
February 4, 2014
J.N.: 2198.00
Page 24
REFERENCES (Cont.)
Smith-Emery Company, Interim Report of Compacted Fill, Tishman Executive Towers-Phase I,
1100 Town and Country Road, Orange, California, dated December 4, 1987 (F.N. 9487)
LeRoy Crandall and Associates, Report of Geotechnical Investigation, Proposed Orange Towers,
Town and Country Road and Lawson Way, Orange, California, dated January 30, 1987, (J.N. ADE85408).
Irvine Soils Engineering Inc., Soils Compaction Report/Foundation Recommendations, Rough
Grading Completed, Town and Country Residential Towers (Building Pads Only) Orange,
California, dated July 2, 1979 (J.N. 1737-10).
Plans
Architectural Site Plan, Building Plans and Building Sections, Sheets A1-1, A1-2, A1-3 and A3-1,
dated December 4, 2013, prepared by TCA Architects (Job # 2013-072).
The Picerne Group
February 4, 2014
J.N.: 2198.00
Page 25
REFERENCES (Cont.)
Aerial Photographs
Photo Source
Google Earth
Google Earth
Google Earth
Google Earth
Google Earth
Google Earth
Google Earth
Google Earth
Google Earth
Google Earth
Google Earth
Google Earth
Google Earth
Google Earth
Google Earth
Continental Aerial Photo, Inc.
Date Flown
3-7-11
4-24-10
11-14-09
5-24-09
10-22-07
1-30-06
12-31-05
6-11-05
4-18-05
12-31-04
4-10-04
3-11-04
11-30-03
4-16-03
6-4-02
2-4-99
10-15-97
1-29-95
6-9-93
1-29-92
1-9-87
5-17-83
1-31-81
2-25-80
12-14-78
12-28-76
1-13-75
10-29-73
2-18-70
3-1-67
3-25-59
12-26-52
Flight No.
Photo No.
C134-36
C117-36
C103-36
C93-12
C85-8
F
218-7
211-7
80033
203-7
181-7
157-7
132-6
61-6
1
261-3-15
AXK-5K
168, 169
152, 153
23, 24
189, 190
10, 11
232, 233
15, 16
13, 14
75
17, 18
14, 15
15, 16
8, 9
270, 271
33, 34
107-109
85-87
APPENDIX A
EXPLORATION LOGS
APPENDIX B
LABORATORY TESTING PROGRAM
The Picerne Group
February 4, 2014
J.N.: 2198.00
LABORATORY TESTING PROGRAM
Soil Classification
Soils encountered within the exploratory borings were initially classified in the field in general
accordance with the visual-manual procedures of the Unified Soil Classification System (ASTM D
2488-93). The samples were re-examined in the laboratory and classifications reviewed and then
revised where appropriate. The assigned group symbols are presented on the Exploration Logs
provided in Appendix A.
In-Situ Moisture Content and Dry Density
Moisture content and dry density of in-place soil materials were determined in representative strata.
Test data are presented on the Exploration Logs, Appendix A.
Percent Passing the No. 200 Sieve
Percent of material passing the No. 200 sieve was determined on selected samples to determine
quantities of “fines”. These tests were performed in accordance with ASTM D1140-97. Test results
are presented on Table B.
Consolidation
Consolidation tests were performed for selected soil samples in general conformance with ASTM D
2435-04. Axial loads were applied in several increments to a laterally restrained 1-inch-high sample.
Loads were applied in geometric progression by doubling the previous load, and the resulting
deformations were recorded at selected time intervals. The test samples were inundated at selected
loads to evaluate the effects of a sudden increase in moisture content (hydro-consolidation potential).
Results of the tests are graphically presented on Plates B-1 through B-4.
Atterberg Limits
Atterberg Limits (Liquid Limit, Plastic Limit, and Plasticity Index) were performed for selected
samples in accordance with ASTM D 4318-05. Pertinent test values are presented within Table B.
Particle Size Analyses
Particle size analyses were performed on representative samples of site materials in accordance with
ASTM D 422-63. The results are presented graphically on the attached Plates B-5 through B-8.
The Picerne Group
February 4, 2014
J.N.: 2198.00
TABLE B
SUMMARY OF LABORATORY TEST RESULTS
Boring
No.
Sample
Depth
(ft.)
Soil Description
B-1
31.5
SM/SP
% Passing #200 Sieve:
8.7%
B-1
40
ML/CL
76.8%
B-1
45
ML/CL
89.8%
B-2
45
ML/CL
79.5%
B-3
20-25
ML
53.1%
B-3
35
CL
B-3
45
CL
B-3
50
CH
Test Results
Liquid Limit:
Plasticity Index:
Liquid Limit:
Plasticity Index:
Liquid Limit:
Plasticity Index:
23.4
7.9
46.8
22.9
51.1
25.7
Note: Additional laboratory test results are provided on the boring logs provided in Appendix A.
APPENDIX C
EXPLORATION LOGS & LABORATORY TEST RESULTS
BY
LEROY CRANDALL AND ASSOCIATES, JANUARY 30, 1986
APPENDIX D
STABILITY ANALYSES
The Picerne Group
February 4, 2014
J.N.: 2198.00
Computer Program
Stability analyses were performed using the computer program Slide by Rocscience. The program
analyzes slope stability problems by a two-dimensional limit equilibrium methods including
Bishop’s, Janbu, Morgenstern & Price, and general limit equilibrium (GLE). The particular method
used for each analysis is indicated on the output plots.
Soil strength can be modeled in a variety of ways including standard Mohr-Coulomb, bilinear MohrCoulomb, and general shear strength relationships. Where materials strengths have anisotropic
properties, the program allows the strength to be modeled by introducing a strength function
depending upon the angle of inclination of the slice base. With this function, anisotropic conditions
typically found in bedrock materials can be modeled.
Potential failure surfaces are determined by a variety of search methods including circular surfaces,
block-specified surfaces, fully-specified surfaces, and random-generated search algorithms. The
program calculates the factor of safety for all possible combinations of surfaces defined by search
method. The program can also model other factors such as groundwater, earthquake loads, and
external loads.
Shear Strengths
The shear strengths used in our analyses were based on direct shear testing and previous experience.
The strength values used are summarized In Table D-1 below:
TABLE D-1
Summary of Shear Strengths
Unit Weight
(pcf)
Cohesion
(psf)
Friction Angle
(degrees)
SP/SM
120
50
34
ML
122
50
30
GP
125
0
41
Material
Results
Results of our analyses are provided on the attached Plates D-1 and D-2
190
Safety Factor
0.000
0.250
1.143
180
0.500
0.750
170
1.000
1.250
Material Name Color
1.500+
SP/SM
120
50
34
ML
122
50
30
GP
125
0
41
140
150
160
300.00 lbs/ft2
Unit Weight Cohesion Phi
(lbs/ 3)
(psf)
(deg)
0
5
10
15
20
25
30
35
40
45
50
55
60
65
70
75
80
85
90
95
100
2198.00 Temporary Slope - 1 to 1.25
Bishop
Albus-Keefe & Associates, Inc.
SLIDEINTERPRET 6.017
Date: 2/4/2014
Plate D-1
190
Safety Factor
0.000
0.250
180
0.500
1.301
0.750
170
1.000
Material Name Color
1.250
1.500+
SP/SM
120
50
34
ML
122
50
30
GP
125
0
41
140
150
160
300.00 lbs/ft2
Unit Weight Cohesion Phi
(lbs/ 3)
(psf)
(deg)
0
10
20
30
40
50
60
70
80
90
100
2198.00 Temporary Slope - 1 to 1.5
Bishop
Albus-Keefe & Associates, Inc.
SLIDEINTERPRET 6.017
Date: 2/4/2014
Plate D-2

February 4, 2014 J.N.: 2198.00 Mr. Joe Zink The Picerne Group

Transcription

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