HomeMy WebLinkAboutAttachment 10 Preliminary Geotechnical InvestigationPRELIMINARY GEOTECHNICAL INVESTIGATION
PROPOSED RESIDENTIAL DEVELOPMENT
EASTERN 2.54 ACRES OF APN 375-291-14
ORANGE, CALIFORNIA
PROJECT NO. 33616.1
FEBRUARY 25, 2020
Prepared For:
C & C Development
14211 Yorba Street, Suite 200
Tustin, California 92780
Attention: Mr. Scott Bering
February 25, 2020
C & C Development Project No. 33616.1
14211 Yorba Street, Suite 200
Tustin, California 92780
Attention: Mr. Scott Bering
Subject: Preliminary Geotechnical Investigation, Proposed Residential Development,
Eastern 2.54 Acres of APN 375-291-14, Orange, California.
LOR Geotechnical Group, Inc., is pleased to present this report summarizing our
geotechnical investigation for the above referenced project. In summary, it is our opinion
that the proposed development is feasible from a geotechnical perspective, provided the
recommendations presented in the attached report are incorporated into design and
construction.
To provide adequate support for the proposed residential structures, we recommend that
a compacted fill mat be constructed beneath footings and slabs. The compacted fill mat
will provide a dense, high-strength soil layer to uniformly distribute the anticipated
foundation loads over the underlying soils. All undocumented fill material and any loose
alluvial materials should be removed from structural areas and areas to receive engineered
compacted fill. The data developed during this investigation indicates that removals on the
order of approximately 5 feet will be required within the currently planned development
areas. The given removal depths are preliminary. The actual depths of the removals should
be determined during the grading operation by observation and/or in-place density testing.
Medium expansive soils and poor R-value quality soils were encountered on the site. A
negligible sulfate content was found for the soils tested. Near completion and/or at the
completion of site grading, additional foundation and subgrade soils should be tested to
verify their expansion potential, soluble sulfate content, and R-value quality.
LOR Geotechnical Group, Inc.
Table of Contents Page No.
INTRODUCTION. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1
PROJECT CONSIDERATIONS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
EXISTING SITE CONDITIONS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
AERIAL PHOTOGRAPH ANALYSIS.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
FIELD EXPLORATION PROGRAM.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
LABORATORY TESTING PROGRAM.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
GEOLOGIC CONDITIONS.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Regional Geologic Setting. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Site Geologic Conditions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Fill. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Older Alluvium.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Groundwater Hydrology.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Surface Runoff.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Mass Movement.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Faulting. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Historical Seismicity.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Secondary Seismic Hazards. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Liquefaction.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Seiches/Tsunamis.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Flooding (Water Storage Facility Failure). . . . . . . . . . . . . . . . . . . . . . . . . 9
Seismically-Induced Landsliding.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Rockfalls. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Seismically-Induced Settlement. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
SOILS AND SEISMIC DESIGN CRITERIA (California Building Code 2019). . . . . . 10
Site Classification.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
CBC Earthquake Design Summary. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
LOR GEOTECHNICAL GROUP, INC.
Table of Contents Page No.
CONCLUSIONS.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
General. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Foundation Support. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Soil Expansiveness. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Sulfate Protection. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Geologic Mitigations.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Seismicity.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
RECOMMENDATIONS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Geologic Recommendations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
General Site Grading.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Initial Site Preparation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Preparation of Fill Areas. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Preparation of Foundation Areas.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Engineered Compacted Fill. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Short-Term Excavations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Slope Construction.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Slope Protection. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Foundation Design.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Settlement. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Building Area Slab-On-Grade. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Exterior Flatwork. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Wall Pressures.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Sulfate Protection. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Preliminary Pavement Design. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
LOR GEOTECHNICAL GROUP, INC.
Construction Monitoring. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Table of Contents Page No.
LIMITATIONS.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
TIME LIMITATIONS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
CLOSURE. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
REFERENCES. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
APPENDICES
Appendix A
Index Map.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-1
Architectural Site Plan. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-2
Regional Geologic Map. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-3
Historical Seismicity Maps. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-4 and A-5
Appendix B
Field Investigation Program. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B
Boring Logs. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-1 through B-6
Boring Log Legend. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-i
Soil Classification Chart. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-ii
Appendix C
Laboratory Testing Program.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C
Gradation Curves. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-1
Atterberg Limits. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-2
Appendix D
Seismic Design Spectra. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . D
LOR GEOTECHNICAL GROUP, INC.
C & C Development Project No. 33616.1
February 25, 2020
INTRODUCTION
During February of 2020, a Preliminary Geotechnical Investigation was performed by LOR
Geotechnical Group, Inc., for proposed residential development of the eastern 2.54 acres
of APN 375-291-14 in the City of Orange, California. The purpose of this investigation was
to conduct a technical evaluation of the geologic setting of the site and to provide
geotechnical design recommendations for the proposed improvements. The scope of our
services included:
•Review of available pertinent geotechnical literature, reports, maps, and agency
information pertinent to the study area;
•Interpretation of aerial photographs of the site and surrounding regions dated 1946
through 2018;
•Geologic field reconnaissance mapping to verify the areal distribution of earth units
and significance of surficial features as compiled from documents, literature, and
reports reviewed;
•A subsurface field investigation to determ ine the physical soil conditions pertinent
to the proposed dev elopment;
•Laboratory testing of selected soil samples obtained during the field investigation;
•Development of geotechnical recommendations for site grading and foundation
design; and
•Preparation of this report summarizing our findings, and providing conclusions and
recommendations for site development.
The approximate location of the site is shown on the attached Index Map, Enclosure A-1,
within Appendix A.
To orient our investigation at the site, you provided us with an Architectural Site Plan,
prepared by IDE Arc Architecture & Planning, dated September 12, 2019, that showed the
proposed development. As noted on that map, the site will be developed with a total of 62
apartment units within two, three-story structures and the associated improvements. The
Architectural Site Plan was utilized as a base map for our field investigation and is
presented as Enclosure A-2, w ithin Appendix A.
1
LOR GEOTECHNICAL GROUP, INC.
C & C Development Project No. 33616.1
February 25, 2020
PROJECT CONSIDERATIONS
The proposed two structures will be three stories in height and are anticipated to be of
wood frame construction with an exterior plaster veneer. Light to moderate foundation
loads are anticipated with such structures. Cuts and fills on the order of a few feet are
anticipated to create the planar building pads.
EXISTING SITE CONDITIONS
The subject site is vacant land, comprising approximately 2.5 acres of an irregular-shaped
portion of a larger 17.23-acre parcel of land which comprises the City of Orange Corporate
Yard and Police Department building, located at the northeast corner of the intersection
at North Batavia Street and W est Struck Avenue. The subject site is situated in the far east
end of the 17.23-acre parcel. The subject site is largely absent of vegetation, with the
exception of dense bushes and trees along the north bound ary and landscaping
improvements consisting of pine trees, ornamental plants, and grass near and/or within the
south side of the subject site along the north side of W est Struck Avenue. The ground
surface of most of the subject site is dirt covered in gravel and/or asphalt grindings and
asphalt, with some bare dirt present. The site is relatively planar with a very gentle fall
towards the south-southwest to W . Struck Avenue. A concrete v-ditch traverses the eastern
site boundary from offsite to the northwest.
Numerous items, trucks, tractors, trailers, plant trimmings, light standards, k-rails, and other
items associated with the site’s current use as a city yard.
The site is bound on the north by commercial buildings, on the east by two sets of railroad
tracks with multi-family residential beyond, on the south by W . Struck Avenue, a fully
improved roadway, followed by commercial buildings, and on the west by the remainder
of the city yard for various departm ents.
AERIAL PHOTOGRAPH ANALYSIS
The aerial photographs reviewed consisted of vertical aerial stereoscopic photographs of
varying scales. W e reviewed imagery available from Google Earth (2020) and from Historic
Aerials (2020).
2
LOR GEOTECHNICAL GROUP, INC.
C & C Development Project No. 33616.1
February 25, 2020
The site consisted of groves with surrounding properties from 1946, the earliest photograph
available, to 1963 when the groves were removed. The site remained vacant until the 1980
photograph when it was a part of the city yard to present day. The southern approximately
half of the site contained asphalt concrete paving in 2002. Photographs from 1980 to 2018
showed the site was used f or storage, similar to that seen today.
Our review of the aerial photographs did not reveal any adverse geologic conditions, such
as possible f aults or landslides, as being present at or within close proximity to the site.
FIELD EXPLORATION PROGRAM
Our subsurface field exploration program was conducted on February 4, 2020 and
consisted of drilling 6 exploratory borings with a truck-mounted Mobile B-61 drill rig
equipped with 8-inch diameter hollow stem augers. The borings were drilled to depths of
approximately 15 to a refusal depth of 41 feet below the existing ground surface. The
approximate locations of our exploratory borings are presented on the attached
Architectural Site Plan, Enclosure A-2 w ithin Appendix A.
The subsurface conditions encountered in the exploratory borings were logged by a
geologist from this firm. Relatively undisturbed and bulk samples were obtained at a
maximum depth interval of 5 feet and returned to our geotechnical laboratory in sealed
containers for further testing and evaluation. A detailed description of the field exploration
program and the boring logs are presented in Appendix B.
LABORATORY TESTING PROGRAM
Selected soil samples obtained during the field investigation were subjected to laboratory
testing to evaluate their physical and engineering properties. Laboratory testing included
in-place moisture content and dry density, laboratory compaction characteristics, direct
shear, sieve analysis, sand equivalent, R-value, expansion index, Atterberg limits, and
soluble sulfate content. A detailed description of the laboratory testing program and the test
results are presented in Appendix C.
3
LOR GEOTECHNICAL GROUP, INC.
C & C Development Project No. 33616.1
February 25, 2020
GEOLOGIC CONDITIONS
Regional Geologic Setting
The subject site is located within northeastern Orange County between the Santa Ana
River to the west and the Peralta Hills to the east. These small hills form a series of low
hills that extend as a northwest trending flank of the larger Santa Ana Mountains to the
east and southeast. The Santa Ana Mountains are in turn one of the several mountain
ranges that form the interior portion of southern California known as the Peninsular Ranges
geomorphic province. This province consists of a series of northwest trending mountains
that extend from the Los Angeles Basin south, to the Mexican border and beyond. The
Santa Ana Mountains themselves form the eastern boundary of Orange County and
contain some of the oldest rocks within the County, the Triassic to Jurassic aged
metasedimentary rocks of the Bedford Canyon formation that formed around 225 million
years ago. Underlying the Bedf ord Canyon formation are units of relatively younger
igneous rocks of Cretaceous age that form the core of the mountains from intrusion of
magma into this area around 65 million years ago. Especially along the western flanks of
the Santa Ana mountains, these older metamorphic and igneous rocks are overlain by
younger rocks of sedimentary and volcanic origin that documents the fluctuating history of
this region from shallow continental sea to near shore continental environments, with
periodic volcanic eruptions.
Erosion of the Santa Ana Mountains to the east and southeast, as well as the hills to the
east, by the Santa Ana Rivera and its tributaries, such as the Santiago Creek to the
east-southeast, has deposited a relatively thick sequence of relatively unconsolidated
alluvium of varies ages and levels in a series of terraces along this broad valley. In their
regional geologic map of the area, the USGS indicated that the site is situated upon older
alluvial materials (Morton and Miller, 2006). This unit was described as composed of
indurated, reddish brown, silty sand alluvial fan deposits. This deposit is considered to
have been deposited in the late to middle Pleistocene age, or on the order of about 11,000
years or slightly older. This older unit has been slightly incised, and replaced with similar,
unconsolidated, m aterials along the active creek beds.
The region, like much of southern California, has numerous faults. These are all associated
with the San Andreas fault zone, located approximately 63 kilometers (39 miles) to the
northeast, that results from the area's location and history as a major plate boundary with
various types of relative motion. Many of these faults have been inactive for millions of
years and are noted only by abrupt changes of rock types. Other faults show evidence that
4
LOR GEOTECHNICAL GROUP, INC.
C & C Development Project No. 33616.1
February 25, 2020
they have been active in geologically recent times, since the Pleistocene Epoch within the
last 11,000 years, but not within the recorded history of Orange County, while other faults
have documented historical activity.
The San Andreas fault, noted above, is the largest known active fault in the region in terms
of anticipated events. The closest known fault, as seen on the Regional Geologic Map,
Enclosure A-3, is the Peralta Hills-El Modeno fault location, approximately 5.5 kilometers
(3.5 miles) to the east. The Peralta Fault may tie into the El Modeno Fault, located
approximately 2.8 kilometers (1.8 miles) northeast of the site. W hile little data is available
on the activity and potential of these faults, these reportedly break late Pleistocene (11,000
to 700,000 years old ) materials and may fault Holocene (from 0 to 11,000 years in age)
alluvial materials which would indicate these f aults are active.
The closest known active fault in relation to the site which data is readily available, is the
W hittier-Elsinore fault, which lies approximately 12.7 kilometers (7.8 miles) to the
northeast. The W hittier fault zone extends along the southwestern base of the Puente Hills.
The W hittier fault joins the Chino fault near Prado Dam, and they merge into the Elsinore
fault zone which trends along the eastern base of the Santa Ana Mountains. The 5.9
magnitude W hittier Narrows earthquake of October 1, of 1987, occurred on a previously
unknown concealed thrust fault approximately 20 kilometers east of downtown Los Angeles
that is now associated as part of the W hittier fault system.
Another well known active fault zone is Newport-Inglewood fault zone, located
approximately 16 kilometers (10 miles) to the west-southwest of the site, extends northwest
from offshore Newport Beach to Inglewood (distance of 40 miles) and, like the W hittier fault
and Elsinore faults, has had documented historical activity. The very destructive 1933 Long
Beach earthquake resulted f rom movement along this fault.
Located approximately 37 kilometers (23 miles) to the north is the Cucamonga-Sierra
Madre fault zone, which marks the southern boundary of the San Gabriel Mountains. This
system is comprised of steeply, north-dipping, thrust, range-front faults along which most
of the uplift of the San Gabriel Mountains, has occurred. The Cucamonga fault marks the
eastern portion of the Sierra Madre fault system, which the San Fernando fault marks the
western portion. It is believed that the Cucamonga fault is capable of producing an
earthquake on the order of 7.0 or greater.
5
LOR GEOTECHNICAL GROUP, INC.
C & C Development Project No. 33616.1
February 25, 2020
Associated with the San Andreas fault zone, the San Jacinto fault zone lies approximately
55 kilometers (34 miles) to the northeast. The San Jacinto fault zone is a sub-parallel
branch of the San Andreas fault zone, extending from the northwestern San Bernardino
area, southward to the El Centro region. This fault has been active in recent times, with
several large magnitude events. It is believed that the San Jacinto fault is capable of
producing an earthquake magnitude on the order of 6.5 or greater.
Site Geologic Conditions
Fill: As encountered within our exploratory boring placed at the site, fill materials to a depth
of 3 feet are present. These materials mainly consisted of asphalt grindings underlain by
silty sand and lean clay with sand.
Older Alluvium: Underlying the fill materials at the site, older alluvial materials were
encountered within all of our exploratory borings to the maximum depths explored. These
units were noted to consist of lean clay with sand and clayey sand with gravel, and lesser
amounts unit of sandy silt. The older alluvial materials were in a relatively stiff to very stiff
and dense state upon first encounter, becoming very dense/very stiff with depth based on
our equivalent Standard Penetration Test (SPT) data and in-place density testing. Refusal
was experienced at depth of approximately 41 feet due to gravel and possible cobbles.
A detailed description of the subsurface soil conditions as encountered within our
exploratory borings is presented on the Boring Logs within Appendix B.
Groundwater Hydrology
Groundwater was not encountered within our exploratory borings advanced to a maximum
depth of approximately 41 feet below the existing ground surface.
Records for nearby wells which were readily available from the State of California
Department of W ater Resources online database (CDW R, 2020) were reviewed as a part
of this investigation.
This database indicates that the nearest water well is state well number 04S09W 19G001S
which is located approximately 0.7 kilometers (0.4 miles) to the north. This well lies at an
elevation of approximately 179 feet above mean sea level (m.s.l.). Recorded groundwater
measurements were available from 1991 to 2010. The records indicate that groundwater
in this well has fluctuated in depth between approximately 170 feet in November of 1992
6
LOR GEOTECHNICAL GROUP, INC.
C & C Development Project No. 33616.1
February 25, 2020
to a high of approximately 91 feet in July of 2006. This results in an approximate elevation
range of 9 feet below m.s.l. to 87 feet above m.s.l. The latest groundwater measurement
of approximately 128 feet was in October of 2010.
As illustrated on Enclosure A-1, the elevation of the site is approximately 180 feet above
mean sea level. Based on the information above, groundwater is anticipated to lie at a
depth greater than 100 f eet in the general site area.
Surface Runoff
Current surface runoff of precipitation waters across the site is generally as sheet flow to
the south-southwest.
Mass Movement
Mass movement features such as landslides, rockfalls, or debris flows within the site
vicinity are not known to exist and no evidence of mass movement was observed on the
site or in the vicinity during our review of aerial photographs or our site reconnaissance.
Faulting
No active or potentially active faults are known to exist at the subject site. In addition, the
subject site does not lie within a current State of California Earthquake Fault Zone (Hart
and Bryant, 2003).
As previously noted, the nearest known fault is the Peralta/El Modeno faults located
approximately 5.5 kilometers (3.5 miles) to the northeast. However, the activity rating of
these faults is not known. The nearest known active fault in relation to the site is the
W hittier fault. The W hittier fault runs along the base of the Puente Hills to the north. At the
closest approach, this fault lies approximately 12.7 kilometers (7.8 miles) to the
north-northeast. According to a study conducted by Cao et al. (2003), the W hittier fault
within the Elsinore fault system has a slip rate of 2.5 mm per year and is anticipated to be
capable of generating an earthquake with a moment magnitude on the order of 6.8. Other
known active faults in the region include the Newport-Inglewood fault located approximately
16 kilometers (10 miles) to the west-southwest. According to the study conducted by Cao
et al. (2003) the Newport-Inglewood fault has a slip rate of 1 mm per year and an
anticipated magnitude of 7.1.
7
LOR GEOTECHNICAL GROUP, INC.
C & C Development Project No. 33616.1
February 25, 2020
The Department of Conservation, California Geological Survey, formerly known as the
Department of Conservation, Division of Mines and Geology, has prepared seismic hazard
zone maps, in accordance with Seismic Hazards Mapping Act for various areas of northern
and southern California. The site and immediate surrounding region are shown on Seismic
Hazard Zone Map of the Orange 7.5 Quadrangle, released April 15, 1998. According to this
map, the site does not lie within an area where historic occurrence of liquefaction, or local
geological, geotechnical, and groundwater conditions indicate a potential for permanent
ground displacements, including earthquake induced landslides, such that mitigation as
defined in Public Resources Code Section 2693(c) w ould be required. Public Resources
Code Section 2693(c) states that "mitigation" means those measures that are consistent
with established practice and that will reduce seismic risk to acceptable levels. An
"acceptable level" is that level that provides reasonable protection of public safety, though
it does not necessarily ensure continued structural integrity and functionality of the project.
Current standards of practice often include a discussion of all potential earthquake sources
within a 100 kilometer (62 mile) radius. However, while there are other large earthquake
faults within a 100 kilometer (62 mile) radius of the site, none of these are considered as
relevant to the site due to the ir greater distance and/or sm aller anticipated magnitudes.
Historical Seismicity
In order to obtain a general perspective of the historical seismicity of the site and
surrounding region a search was conducted for seismic events at and around the area
within various radii. This search was conducted utilizing the historical seismic search
website of the USGS. This website conducts a search of a user selected cataloged seismic
events database, within a specified radius and selected magnitudes, and then plots the
events onto a map. At the time of our search, the database contained data from January
1, 1932 through February 16, 2020.
In our first search, the general seismicity of the region was analyzed by selecting an
epicenter map listing all events of magnitude 4.0 and greater, recorded since 1932, within
a 100 kilometer (62 mile)radius of the site, in accordance with guidelines of the California
Division of Mines and Geology. This map illustrates the regional seismic history of
moderate to large events. As depicted on Enclosure A-4, w ithin Appendix A, the site lies
within a relatively quiet region lying east of the more active region to the west associated
with the Newport-Inglewood fault zone to the west.
8
LOR GEOTECHNICAL GROUP, INC.
C & C Development Project No. 33616.1
February 25, 2020
In the second search, the micro seismicity of the area lying within a 15 kilometer (9.3 mile)
radius of the site was examined by selecting an epicenter map listing events on the order
of 2.0 and greater since 1978. In addition, only the “A” events, or most accurate events
were selected. Caltech indicates the accuracy of the “A” events to be approximately 1 km.
The results of this search is a map that presents the seismic history around the area of the
site with much greater detail, not permitted on the larger map. The reason for limiting the
events to the last 40± years on the detail map is to enhance the accuracy of the map.
Events recorded prior the mid 1970's are generally considered to be less accurate due to
advancements in technology. As depicted on this map, Enclosure A-5, while not distinct,
the Newport-Inglewood fault is conspicuous as a northwest trending lineation of small
seismic events located southwest of the site. In addition to these events there is a distinct
band of seismic events north of the site, roughly trending with the W hittier fault zone.
In summary, the historical seismicity of the site entails numerous small to medium
magnitude earthquake events occurring around the subject site, predominately associated
with the presence of the San Jacinto fault zone. Any future developments at the subject
site should anticipate that moderate to large seismic events could occur very near the site.
Secondary Seismic Hazards
Other secondary seismic hazards generally associated with severe ground shaking during
an earthquake include liquefaction, seiches and tsunamis, earthquake induced flooding,
landsliding and rockfalls, and seismic-induced settlement.
Liquefaction: The potential for liquefaction generally occurs during strong ground shaking
within granular loose sediments where the groundwater is usually less than 50 feet. As the
site is underlain by relatively dense/stif f to dense/very stiff deposits of older alluvium and
the depth to groundwater is considered to be greater than 50 feet, the possibility of
liquefaction within these units is considered nil.
Seiches/Tsunamis: The potential for the site to be affected by a seiche or tsunami
(earthquake generated wave) is considered nil due to the absence of any large bodies of
water near the site.
Flooding (W ater Storage Facility Failure): There are no large water storage facilities
located on or upstream near the site which could possibly rupture during an earthquake
and af fect the site by flooding.
9
LOR GEOTECHNICAL GROUP, INC.
C & C Development Project No. 33616.1
February 25, 2020
Seismically-Induced Landsliding: Since the site is situated on a relatively flat plain, the
potential f or seismically induced mass movement is considered nil.
Rockfalls: No large, exposed, loose or unrooted boulders that could affect the integrity of
the site are present abov e the site.
Seismically-Induced Settlement: Settlement generally occurs within areas of loose,
granular soils with relatively low density. Since the site is underlain by dense/stif f to
dense/very stiff older alluvial materials, the potential for settlement is considered low. In
addition, the earthwork operations recommended to be conducted during the development
of the site will mitigate any near surface loose soil conditions.
SOILS AND SEISMIC DESIGN CRITERIA (California Building Code 2019)
Design requirements for structures can be found within Chapter 16 of the 2019 California
Building Code (CBC) based on building type, use and/or occupancy. The classification of
use and occupancy of all proposed structures at the site, and thus the design
requirements, shall be the responsibility of the structural engineer and the building official.
For structures at the site to be designed in accordance with the provisions of Chapter 16,
the subject site specif ic criteria is provided below:
Site Classification
Chapter 20 of the ASCE 7-16 defines six possible site classes for earth materials that
underlie any given site. Bedrock is assigned one of three of these six site classes and
these are: A, B, or C. Per ASCE 7-16, Site Class A and Site Class B shall be measured
on-site or estimated by a geotechnical engineer, engineering geologist or seismologist for
competent rock with moderate fracturing and weathering. Site Class A and Site Class B
shall not be used if more than 10 feet of soil is between the rock surface and bottom of the
spread footing or mat foundation. Site Class C can be used for very dense soil and soft
rock with values greater than 50 blows per foot. Site Class D can be used for stiff soil with
values ranging from 15 to 50 blows per foot. Site Class E is for soft clay soils with values
less than 15 blows per foot. Our Standard Penetration Test (SPT) data indicate that the
materials beneath the site are considered Site Class D soils.
10
LOR GEOTECHNICAL GROUP, INC.
C & C Development Project No. 33616.1
February 25, 2020
CBC Earthquake Design Summary
As determined in the previous section, earthquake design criteria have been formulated
for the site. However, these values should be reviewed and the final design should be
performed by a qualified structural engineer familiar with the region. Our design values are
provided in Appendix E.
CONCLUSIONS
General
This investigation provides a broad overview of the geotechnical and geologic factors which
are expected to influence future site planning and development. On the basis of our field
investigation and testing program, it is the opinion of LOR Geotechnical Group, Inc., that
the proposed development is feasible from a geotechnical standpoint, provided the
recommendations presented in this report are incorporated into design and implemented
during grading and construction.
The subsurface conditions encountered in our exploratory borings are indicative of the
locations explored. The subsurface conditions presented here are not to be construed as
being present the same everywhere on the site. If conditions are encountered during the
construction of the project which differ significantly from those presented in this report, this
firm should be notified immediately so we may assess the impact to the recommendations
provided.
Foundation Support
Based upon the field investigation and test data, it is our opinion that the existing fill/topsoil
and fill soils will not, in their present condition, provide uniform and/or adequate support
for the proposed improvements. Lef t as is, this condition could cause unacceptable
differential and/or overall settlements upon application of the anticipated foundation loads.
To provide adequate support for the proposed structural improvements, we recommend
that a compacted f ill mat be constructed beneath f ootings and slabs. T his compacted fill
mat will provide a dense, high-strength soil layer to uniformly distribute the anticipated
foundation loads over the underlying soils. In addition, the construction of this compacted
fill mat will allow for the removal of the undocumented fill soils that are present within the
proposed building areas. Conventional foundation systems, using either individual spread
11
LOR GEOTECHNICAL GROUP, INC.
C & C Development Project No. 33616.1
February 25, 2020
footings and/or continuous wall footings, will provide adequate support for the anticipated
downward and lateral loads w hen utilized in conjunction with the recommended f ill mat.
Soil Expansiveness
Our laboratory testing found the soils tested to have a medium expansion potential.
Therefore, recommendations for low expansive soils are given in the Foundation Design,
Building Area Slab-on-Grade, and Ex terior Flatwork sections of this report.
Careful evaluation of on-site soils and any import fill for their expansion potential should
be conducted during the grading operation.
Sulfate Protection
The results of the soluble sulfate tests conducted on selected subgrade soils expected to
be encountered at foundation levels indicate that there is a negligible sulfate exposure to
concrete elements in contact with the on site soils per the 2019 CBC. Therefore, no
specific recommendations are given for concrete elements to be in contact with the onsite
soils.
Geologic Mitigations
No special geologic recommendation methods are deemed necessary at this time, other
than the geotechnical recommendations provided in the f ollowing sections.
Seismicity
Seismic ground rupture is generally considered most likely to occur along pre-existing
active faults. Since no known faults are known to exist at, or project into the site, the
probability of ground surf ace rupture occurring at the site is considered nil.
Due to the site’s close proximity to the faults described above, it is reasonable to ex pect
a strong ground motion seismic event to occur during the lifetime of the proposed
development on the site. Large earthquakes could occur on other faults in the general
area, but because of their lesser anticipated magnitude and/or greater distance, they are
considered less significant than the faults described above from a ground motion
standpoint.
12
LOR GEOTECHNICAL GROUP, INC.
C & C Development Project No. 33616.1
February 25, 2020
The effects of ground shaking anticipated at the subject site should be mitigated by the
seismic design requirements and procedures outlined in Chapter 16 of the California
Building Code. However, it should be noted that the current building code requires the
minimum design to allow a structure to remain standing after a seismic event, in order to
allow for safe evacuation. A structure built to code m ay still sustain damage which might
ultimately result in the dem olishing of the structure (Larson and Slosson, 1992).
RECOMMENDATIONS
Geologic Recommendations
No special geologic recommendation m ethods are deemed necessary at this time, other
than the geotechnical recommendations provided in the f ollowing sections.
General Site Grading
It is imperative that no clearing and/or grading operations be performed without the
presence of a qualified geotechnical engineer. An on-site, pre-job meeting with the owner,
the developer, the contractor, and geotechnical engineer should occur prior to all grading
related operations. Operations undertaken at the site without the geotechnical engineer
present may result in exclusions of affected areas from the final compaction report for the
project.
Grading of the subject site should be performed in accordance with the following
recommendations as well as applicable portions of the California Building Code, and/or
applicable local ordinances.
All areas to be graded should be stripped of significant vegetation and other deleterious
materials.
It is our recommendation that any existing fills under any proposed flatwork and/or paved
areas be removed and replaced with engineered compacted fill. If this is not done,
premature structural distress (settlement) of the flatwork and pavement may occur. Any
undocumented fills encountered during grading should be completely removed and
cleaned of significant deleterious materials. These may then be reused as compacted fill.
Cavities created by removal of undocumented fill soils and/or subsurface obstructions
should be thoroughly cleaned of loose soil, organic matter and other deleterious materials,
13
LOR GEOTECHNICAL GROUP, INC.
C & C Development Project No. 33616.1
February 25, 2020
shaped to provide access for construction equipment, and backfilled as recommended in
the following Engineered Compacted Fill section of this report.
Initial Site Preparation
Any and all existing uncontrolled fills and any loose/soft native alluvial soils should be
removed from structural areas and areas to receive structural fills. The data developed
during this investigation indicates that removals on the order of 5 feet from existing grades
will be required to encounter competent older alluvium. However, deeper removals may be
required locally. Removals should extend horizontally at a distance equal to the depth of
the removals plus proposed fill and at least a minimum of 5 feet. The actual depths of
removals should be determined during the grading operation by observation and/or by in-
place density testing.
Preparation of Fill Areas
After completion of the removals described above and prior to placing fill, the surfaces of
all areas to receive fill should be scarified to a depth of at least 6 inches. The scarified soil
should be brought to near optimum moisture content and compacted to a relative
compaction of at least 90 percent (AST M D 1557).
Preparation of Foundation Areas
All footings should rest upon a minimum of 24 inches of properly compacted fill material
placed over competent natural alluvial soils. In areas where the required fill thickness is not
accomplished by the removal of unsuitable soils, the footing areas should be further
subexcavated to a depth of at least 24 inches below the proposed footing base grade, with
the subexcavation extending at least 5 feet beyond the footing lines. The bottom of this
excavation should then be scarified to a depth of at least 6 inches, brought to between 2
to 4 percent optimum moisture content, and recompacted to at least 90 percent relative
compaction (ASTM D 1557) prior to refilling the excavation to grade as properly compacted
fill. Fill areas should not be constructed so as to place structures across any area where
the maximum depth of fill to minimum depth of fill is greater than a 3:1 ratio.
To provide adequate support, concrete slabs-on-grade should bear on a minimum of 24
inches of compacted soil. The remedial grading recommended above is anticipated to
accomplish the minimum 24 inches of compacted fill. The final pad surfaces should be
rolled to provide smooth, dense surf aces upon which to place the concrete.
14
LOR GEOTECHNICAL GROUP, INC.
C & C Development Project No. 33616.1
February 25, 2020
Engineered Compacted Fill
Based upon our preliminary observations and laboratory results, most of the upper site
soils consist of lean clays which have a medium expansion potential. In general, these soils
can be used as structural fills, below foundations, provided that reinforcement measures
are incorporated in the desig n to counteract expansive soil behavior.
Unless approved by the geotechnical eng ineer, rock or similar irreducible material with a
maximum dimension greater than 6 inches should not be buried or placed in f ills.
Import fill, if required, should be inorganic, non-expansive granular soils free from rocks or
lumps greater than 6 inches in maximum dimension. Sources for import fill should be
approved by the geotechnical engineer prior to their use.
Fill should be spread in maximum 8-inch uniform, loose lifts, with each lift brought to 2 to
4 percent above optimum moisture content prior to, during and/or after placement, and
compacted to a relative compaction of at least 90 percent in accordanc e with ASTM D
1557.
Based upon the relative compaction of the near surface soils determined during this
investigation and the relative compaction anticipated for compacted fill soil, we estimate
a compaction shrinkage factor of approximately 10 to 15 percent. Therefore, 1.10 to 1.15
cubic yards of in-place materials would be necessary to yield one cubic yard of properly
compacted fill material. Subsidence is anticipated to be 0.10 feet. These values are for
estimating purposes only, and are exclusive of losses due to stripping or the removal of
subsurface obstructions.
These values may vary due to differing conditions within the project boundaries and the
limitations of this investigation. Shrinkage should be monitored during construction. If
percentages vary, provisions should be made to revise final grades or adjust quantities of
borrow or export.
As previously noted, the on-site clayey soils have potential for expansion. Therefore, a
careful evaluation of on-site and any imported soils for their expansion potential should be
conducted during the grading operation.
15
LOR GEOTECHNICAL GROUP, INC.
C & C Development Project No. 33616.1
February 25, 2020
Short-Term Excavations
Following the California Occupational and Safety Health Act (CAL-OSHA) requirements,
excavations 5 feet deep and greater should be sloped or shored. All excavations and
shoring should conf orm to CAL-OSHA requirements.
Short-term excavations 5-feet deep and greater shall conform to Title 8 of the California
Code of Regulations, Construction Safety Orders, Section 1504 and 1539 through 1547.
Based on our exploratory borings, it appears that Type C soil is the predominant type of
soil on the project and all short-term excavations should be based on this type of soil.
Deviation from the standard short-term slopes are permitted using Option 4, Design by a
Registered Professional Engineer (Section 1541.1).
Short-term slope construction and maintenance are the responsibility of the contractor, and
should be a consideration of his methods of operation and the actual soil conditions
encountered.
Slope Construction
Preliminary data indicates that cut and fill slopes should be constructed no steeper than
two horizontal to one vertical. Fill slopes should be overfilled during construction and then
cut back to expose fully compacted soil. A suitable alternative would be to compact the
slopes during construction, then roll the final slopes to provide dense, erosion-resistant
surfaces.
Slope Protection
Since the site soils are susceptible to erosion by running water, measures should be
provided to prevent surface water from flowing over slope faces. Slopes at the project
should be planted with a deep rooted ground cover as soon as possible after completion.
The use of succulent ground covers such as iceplant or sedum is not recommended. If
watering is necessary to sustain plant growth on slopes, the watering system should be
monitored to assure proper operation and to prev ent over watering.
Foundation Design
Since the site is underlain by medium expansive soils, we recommend that the planned
buildings be supported on reinforced, stiffened slab foundations resting over 24 inches of
16
LOR GEOTECHNICAL GROUP, INC.
C & C Development Project No. 33616.1
February 25, 2020
engineered compacted fill placed over competent older alluvium. The design of the slab
foundation could be performed in conformance to the Wire Reinforcement Institute (WRI)
method or the Post-Tensioning Institute (PTI) method.
For the application of the WRI method, an average, effective plasticity index of 18 is
recommended for foundation design. The slab thickness should be a minimum of 4 inches
and should have a reinforcement of at least Asfy equal to 2,900 pounds. This could consist
of #3 reinforcing bars of 60-grade steel placed at a maximum spacing of 18 inches on
center, each way or equivalent. Interior stiffening concrete beams should be placed at a
spacing not to exceed 17 feet. External concrete beams should be provided around the
perimeter of the slab. The minimum beam dimensions should be 24 inches high and 12
inches wide, and embedded approximately 18 inches below the lowest adjacent grade. The
beams should be properly reinforced to resist the moment and shears caused by the
differential heave of the expansive soil. Minimum beam reinforcement should be two #5
rebars at top of beam and two #5 rebars at bottom. Stirrups may be added, particularly in
the perimeter beams, to account for concentrated and exterior wall loads. These
reinforcement, depth, and spacing recommendations should be considered minimum. The
actual requirements for slab-on-grade foundations design and construction should be
provided by a structural engineer experienced in these matters.
The above recommendations were developed for medium expansive soils with an average,
effective plasticity index of 18. These conditions should be verified during the site grading
by additional evaluation of on-site and any imported soils for their expansion potential and
plasticity characteristics.
If slab-on-grade foundations per the PTI method are proposed, the following geotechnical
parameters should be used for design:
• Edge Moisture Variation Distance, em:
Center Lift Loading Conditions:9.0 ft
Edge Lift Loading Conditions:7.5 ft
• Differential Swell, ym:
Center Lift 0.3 in
Edge Lift 0.65 in
• Subgrade Soil Friction Coefficient, µ: 0.30
17
LOR GEOTECHNICAL GROUP, INC.
C & C Development Project No. 33616.1
February 25, 2020
The above design parameters are based upon the data collected during our site
investigation and are in accordance with Design of Post-Tensioned Slabs-on-Ground, third
edition, published by the Post-Tensioning Institute.
For preliminary sizing of foundations, we recommend an allowable bearing pressure of
1,500 pounds per square foot (psf) to be utilized for foundations with a minimum width of
12 inches and a m inimum depth of 18 inches below lowest adjacent grade. This bearing
pressure may be increased by 200 psf for each additional foot of width, and by 400 psf for
each additional f oot of depth, up to a m aximum of 4,000 psf .
The above values are net pressures; therefore, the weight of the foundations and the
backfill over the foundations may be neglected when computing dead loads. The values
apply to the maximum edge pressure for foundations subjected to eccentric loads or
overturning. The recommended pressures apply for the total of dead plus frequently
applied live loads, and incorporate a factor of safety of at least 3.0. The allowable bearing
pressures may be increased by one-third for temporary wind or seismic loading. The
resultant of the combined vertical and lateral seismic loads should act within the middle
one-third of the footing width. The maximum calculated edge pressure under the toe of
foundations subjected to eccentric loads or overturning should not exceed the increased
allowable pressure.
Resistance to lateral loads will be provided by passive earth pressure and base friction. For
foundations bearing against compacted fill, passive earth pressure may be considered to
be developed at a rate of 300 pounds per square foot per foot of depth. Base friction may
be computed at 0.30 times the normal load. Base friction and passive earth pressure may
be combined without reduction. These values are for dead load plus live load and may be
increased by one-third f or wind or seismic loading.
Settlement
Total settlement of individual foundations will vary depending on the width of the foundation
and the actual load supported. Maximum settlement of shallow foundations designed and
constructed in accordance with the preceding recommendations are estimated to be on the
order of 0.5 inch. Differential settlements between adjacent footings should be about one-
half of the total settlement. Settlement of all foundations is expected to occur rapidly,
primarily as a result of elastic compression of supporting soils as the loads are applied, and
should be essentially completed shortly after initial application of the loads.
18
LOR GEOTECHNICAL GROUP, INC.
C & C Development Project No. 33616.1
February 25, 2020
Building Area Slab-On-Grade
To provide adequate support, concrete slabs-on-grade should bear on a minimum of 24
inches of compacted soil placed and maintained at 2 to 4 percent above optimum moisture
content. The final pad surfaces should be rolled to provide smooth, dense surfaces.
Concrete slabs-on-grade should be a minimum of 5 inches in thickness with No. 4 bars
spaced 12 inches on center each way. A 4-inch rock base should also be installed beneath
the slab.
Slabs to receive moisture-sensitive coverings should be provided with a moisture vapor
retarder/barrier. W e recommend that a vapor retarder/barrier be designed and constructed
according to the American Concrete Institute 302.1R, Concrete Floor and Slab
Construction, which addresses moisture vapor retarder/barrier construction. At a minimum,
the vapor retarder/barrier should comply with ASTM E1745 and have a nominal thickness
of at least 10 mils. The vapor retarder/barrier should be properly sealed, per the
manufacturer's recommendations, and protected from punctures and other damage. Per
the Portland Cement Association (www.cement.org/tech/cct_con_vapor_retarders.asp),
for slabs with vapor-sensitive coverings, a layer of dry, granular material (sand) should be
placed under the vapor retarder/barrier. For slabs in humidity-controlled areas, a layer of
dry, granular material (sand) should be placed abov e the vapor retarder/barrier.
The slabs should be protected from rapid and excessive moisture loss which could result
in slab curling. Careful attention should be given to slab curing procedures, as the site area
is subject to large temperature extremes, humidity, and strong winds.
Exterior Flatwork
To provide adequate support, exterior flatwork improvements should rest on a minimum
of 12 inches of soil compacted to at least 90 percent (AST M D 1557).
If medium expansive soils are found underlying flatwork areas, these areas should be
pre-soaked to approximately 4 percent above the optimum moisture content to a minimum
depth of 18 inches.
General flatwork such as sidewalk, patios, curbs, etc., should have a thickness of at least
4 inches, with saw cuts every 10 feet or less. Driveways should be at least 6-inch thick,
with saw cuts every 15 feet or less.
19
LOR GEOTECHNICAL GROUP, INC.
C & C Development Project No. 33616.1
February 25, 2020
Reinforcement should be provided for all sidewalks, patio slabs, and driveways with a
minimum dimension greater than 5 feet. This should consist of #3 rebars of 60-grade steel
placed at a maximum spacing of 18 inches on center, each way Reinforcement for curbing
should be one continuous #4 rebars at top and bottom .
Flatwork surface should be sloped a minimum of 1 percent away from buildings and
slopes, to approved drainage structures.
W all Pressures
The design of footings for retaining structures should be performed in accordance with the
recommendations described earlier under Preparation of Foundation Areas and
Foundation Design. For design of retaining wall footings, the resultant of the applied loads
should act in the middle one-third of the footing, and the maximum edge pressure should
not exceed the basic allowable value without increase.
For design of retaining walls unrestrained against movement at the top, we recommend an
equivalent fluid density of 37 pounds per cubic foot (pcf) be used. This assumes level
backfill consisting of recompacted, non-expansive, soils placed against the structures and
with the backcut slope extending upward from the base of the stem at 35 degrees from the
vertical or flatter.
To avoid overstressing or excessive tilting during placement of backfill behind walls, heavy
compaction equipment should not be allowed within the zone delineated by a 45 degree
line extending from the base of the wall to the f ill surface.
The backfill directly behind the walls should be compacted using light equipment such as
hand operated vibrating plates and rollers. No material larger than 3-inches in diameter
should be placed in direct contact w ith the wall.
W all pressures should be verified prior to construction, when the actual backfill materials
and conditions have been determined. Recommended pressures are applicable only to
level, non-expansive, properly drained backf ill (with no additional surcharge loadings).
If inclined backfills are proposed, this firm should be contacted to develop appropriate
active earth pressure parameters. Toe bearing pressure for non-structural walls on soils,
not prepared as described earlier under Preparation of Foundation Areas, should not
exceed California Building Code values.
20
LOR GEOTECHNICAL GROUP, INC.
C & C Development Project No. 33616.1
February 25, 2020
The parameters given above are based on the assumption that granular, non-expansive,
compacted sandy soils will be used as wall backfills. The preceding parameters were
developed assuming that the sandy backfill material may have a friction angle of
approximately 32 degrees and a compacted moist unit weight of approximately 120 pcf.
These materials may likely will require importation to the site. Much of the surficial site soils
are expansive clayey materials which normally have low permeability, uncertain behavior,
and exert higher lateral earth pressures on retaining structures. Therefore, we recommend
that these soils do not be used w ithin wall backfill areas.
Sulfate Protection
The results of the soluble sulfate tests conducted on selected subgrade soils expected to
be encountered at f oundation levels are presented on Enclosure C.
Based on the test results it appears that there is a negligible sulfate exposure to concrete
elements in contact with on site soils. T he CBC, therefore, does not recommend special
design criteria for concrete elements in conduct with such materials.
Preliminary Pavement Design
Testing and design for preliminary on-site pavement was conducted in accordance with the
California Highway Design Manual. Based upon our preliminary sampling and testing, and
upon a Traffic Index typical for such projects, it appears that the structural section
tabulated below should provide satisfactory pavement for the subject pavement
improvements:
AREA T.I.DESIGN
R-VALUE PRELIMINARY SECTION
Parking and Drive Areas (light
vehicular traffic and occasional
truck traffic)
6.0 5 0.25’ AC/1.15' AB
AC - Asphalt Concrete
AB - Class 2 Aggregate Base
21
LOR GEOTECHNICAL GROUP, INC.
C & C Development Project No. 33616.1
February 25, 2020
The above structural section is predicated upon 90 percent relative compaction (ASTM D
1557) of all utility trench backfills and 95 percent relative compaction (ASTM D 1557) of
the upper 12 inches of pavement subgrade soils and of any aggregate base utilized. In
addition, the aggregate base should meet Caltrans specifications for Class 2 Aggregate
Base.
In areas of the pavement which will receive high abrasion loads due to start-ups and stops,
or where trucks will move on a tight turning radius, consideration should be given to
installing concrete pads. Such pads should be a minimum of 0.5-foot thick concrete, with
a 0.35-foot thick aggregate base. Concrete pads are also recommended in areas adjacent
to trash storage areas where heavier loads will occur due to operation of trucks lifting trash
dumpsters. The recommended 0.5 feet thick portland cem ent concrete (PCC) pavement
section should have a minimum modulus of rupture (MR) of 550 pounds per square inch
(psi).
It should be noted that all of the above pavement design was based upon the results of
preliminary sampling and testing, and should be verified by additional sampling and testing
during construction when the actual subg rade soils are exposed.
Construction Monitoring
Post investigative services are an important and necessary continuation of this
investigation. Project plans and specifications should be reviewed by the project
geotechnical consultant prior to construction to confirm that the intent of the
recommendations presented herein have been incorporated into the design. Additional
expansion index, R-value, and soluble sulfate testing may be required during site rough
grading.
During construction, sufficient and timely geotechnical observation and testing should be
provided to correlate the findings of this investigation with the actual subsurface conditions
exposed during construction. Items requiring observation and testing include, but are not
necessarily limited to, the f ollowing:
1.Site preparation-stripping and removals.
2.Excavations, including approval of the bottom of excavation prior to filling.
3.Scarifying and recompacting prior to fill placement.
22
LOR GEOTECHNICAL GROUP, INC.
C & C Development Project No. 33616.1
February 25, 2020
4.Subgrade preparation f or pavements and slabs-on-g rade.
5.Placement of engineered compacted fill and backfill, including approval of fill
materials and the performance of sufficient density tests to evaluate the degree of
compaction being achieved.
6.Foundation excavations.
LIMITATIONS
This report contains geotechnical conclusions and recommendations developed solely for
use by C & C Development, and their design consultants, for the purposes described
earlier. It may not contain sufficient information for other uses or the purposes of other
parties. The contents should not be extrapolated to other areas or used for other facilities
without consulting LOR Geotechnical Group, Inc.
The recommendations are based on interpretations of the subsurface conditions concluded
from information gained from subsurface explorations and a surficial site reconnaissance.
The interpretations may differ from actual subsurface conditions, which can vary
horizontally and vertically across the site. If conditions are encountered during the
construction of the project which differ significantly from those presented in this report, this
firm should be notified immediately in order that we may assess the impact to the
recommendations provided.
Due to possible subsurface variations, all aspects of field construction addressed in this
report should be observed and tested by the project geotechnical consultant.
If parties other than LOR Geotechnical Group, Inc., provide construction monitoring
services, they must be notified that they will be required to assume responsibility for the
geotechnical phase of the project being completed by concurring with the
recommendations provided in this report or by providing alternative recommendations.
The report was prepared using generally accepted geotechnical engineering practices
under the direction of a state licensed geotechnical engineer. No warranty, expressed or
implied, is made as to conclusions and prof essional advice included in this report.
23
LOR GEOTECHNICAL GROUP, INC.
C & C Development Project No. 33616.1
February 25, 2020
Any persons using this report for bidding or construction purposes should perform such
independent investigations as deemed necessary to satisfy themselves as to the surface
and subsurface conditions to be encountered and the procedures to be used in the
performance of work on this project.
TIME LIMITATIONS
The findings of this report are valid as of this date. Changes in the condition of a property
can, however, occur with the passage of time, whether they be due to natural processes
or the work of man on this or adjacent properties. In addition, changes in the Standards-of-
Practice and/or Governmental Codes may occur. Due to such changes, the findings of this
report may be invalidated wholly or in part by changes beyond our control. Therefore, this
report should not be relied upon after a significant amount of time without a review by LOR
Geotechnical Group, Inc., verifying the suitability of the conclusions and recommendations.
24
LOR GEOTECHNICAL GROUP, INC.
REFERENCES
American Society of Civil Engineers, 2016, Minimum Design Load for Buildings and other
Structures, ASCE 7-16.
California Building Standards Commission, 2019, Calif ornia Building Code.
C a l i f o r n i a D e p a r t m e n t o f W a t e r R e s o u r c e s , 2 0 2 0 ,
http://www.water.ca.gov/waterdatalibrary/.
California Division of Mines and Geology, 1998, Seismic Hazards Zone Map, Orange
Quadrangle.
Google Earth, 2020, Im agery from various years, www.google.com/earth.
Hart, E.W . and W .A. Bryant, 1997, revised 2003, Fault-Rupture Hazard Zones in California,
Alquist-Priolo Earthquake Fault Zoning Act with Index to Earthquake Fault Zones Maps:
California Dept. of Conservation Division of Mines and Geology Special Publication 42,
Revised Edition with Supplements 1, 2 and 3.
Historic Aerials, 2020, Im agery from various years, www.historicaerials.com.
IDE Arc Architecture and Planning, 2019, Architectural Site Plan, City Yard, dated
September 12, 2019.
Larson, R., and Slosson, J., 1992, The Role of Seismic Hazard Evaluation in Engineering
Reports, in Engineering Geology Practice in Southern California, AEG Special Publication
Number 4, pp 191-194.
Morton, D.M. and Matti, J.C., 2006, Geologic Map of the San Bernardino and Santa Ana
30' X 60' Quadrangles, California, Open-File Report 2006-1217.
OSPHD, 2020 ,US Seism ic Design Maps, https://seism icmaps.org.
U.S.G.S., 2020, https://earthq uake.usgs.gov/earthquakes/search/.
26
LOR GEOTECHNICAL GROUP, INC.
APPENDIX A
Index Map, Architectural Site Plan,
Regional Geologic Map,
and
Historical Seismicity Maps
LOR GEOTECHNICAL GROUP, INC.
APPENDIX B
Field Investigation Program and Boring Logs
LOR GEOTECHNICAL GROUP, INC.
APPENDIX B
FIELD INVESTIGATION
Subsurface Exploration
The site was investigated on February 4, 2020 and consisted of advancing 6 exploratory
borings to depths from approximately 15 feet and 41 feet below the existing ground
surface. The approximate locations of the borings are shown on Enclosure A-2, within
Appendix A.
The drilling exploration was conducted using a truck-mounted Mobile B-61 drill rig equipped
with 8-inch diameter hollow stem augers. The soils were continuously logged by our
geologist who inspected the site, created detailed logs of the borings, obtained
undisturbed, as well as disturbed, soil samples for evaluation and testing, and classified
the soils by visual examination in accordance with the Unified Soil Classification System.
Relatively undisturbed samples of the subsoils were obtained at a maximum interval of 5
feet. The samples were recovered by using a California split barrel sampler of 2.50 inch
inside diameter and 3.25 inch outside diameter or a Standard Penetration Sampler (SPT)
from the ground surface to the total depth explored. The samplers were driven by a 140
pound automatic trip hammer dropped from a height of 30 inches. The number of hammer
blows required to drive the sampler into the ground the final 12 inches were recorded and
further converted to an equivalent SPT N-value. Factors such as efficiency of the automatic
trip hammer used during this investigation (80%), borehole diameter (8"), and rod length
at the test depth were considered for further computing of equivalent SPT N-values
corrected for field procedures ( N60) which are included in the boring logs, Enclosures B-1
through B-6.
The undisturbed soil samples were retained in brass sample rings of 2.42 inches in
diameter and 1.00 inch in height, and placed in sealed containers. Disturbed soil samples
were obtained at selected levels within the borings and placed in sealed containers for
transport to the laboratory.
All samples obtained were taken to our geotechnical laboratory for storage and testing.
Detailed logs of the borings are presented on the enclosed Boring Logs, Enclosures B-1
through B-6. A Boring Log Legend and Soil Classification Chart are presented on
Enclosures B-i and B-ii, respectively.
B
LOR GEOTECHNICAL GROUP, INC.
CONSISTENCY OF SOIL
SANDS
SPT BLOW S CONSISTENCY
0 -4 V ery Loose
4 -1 0 Loose
1 0 -3 0 M edium Dense
3 0 -5 0 Dense
Ov er 5 0 V ery Dense
COHESIV E SOILS
SPT BLOW S CONSISTENCY
0 -2 V ery Sof t
2 -4 Sof t
4 -8 M edium
8 -1 5 St if f
1 5 -3 0 V ery St if f
3 0 -6 0 Hard
Ov er 6 0 V ery Hard
SAM PLE KEY
Symbol Descript ion
INDICA TES CA LIFORNIA
SPLIT SPOON SOIL
SA M PLE
INDICA TES BULK SA M PLE
INDICA TES SA ND CONE
OR NUCLEA R DENSITY
TEST
INDICA TES STA NDA RD
PENETRA TION TEST (SPT)
SOIL SA M PLE
TYPES OF LABORATORY TESTS
1 A t t erberg Limit s
2 Consolidat ion
3 Direc t Shear (undist urbed or remolded)
4 Ex pansion Index
5 Hy drom et er
6 Organic Cont ent
7 Proct or (4 ", 6 ", or Cal2 1 6 )
8 R-v alue
9 Sand Equiv alent
1 0 Siev e A naly sis
1 1 Soluble Sulf at e Cont ent
1 2 Sw ell
1 3 W ash 2 0 0 Siev e
BORING LOG LEGEND
PROJECT:637 W. STRUCK AVENUE, ORANGE, CALIFORNIA PROJECT NO.: 33616.1
CLIENT:C & C DEVELOPMENT ENCLOSURE:B-i
LOR Geotechnical Group, Inc.DATE:FEBRUARY 2020
PA RTICLE SIZE LIM ITS
BOULDERS COBBLES
GRAV EL SAND
SILT OR CLAY
COARSE FINE COARSE M EDIUM FINE
1 2" 3" 3/4 " No. 4 No. 10 No. 40 20 0
(U.S. STANDARD SIEVE SIZE)
SOIL CLASSIFICATION CHART
PROJECT 637 W. STRUCK AVENUE, ORANGE, CALIFORNIA PROJECT NO. 33616.1
CLIENT:C & C DEVELOPMENT ENCLOSURE:B-ii
LOR Geotechnical Group, Inc.DATE:FEBRUARY 2020
113.3
121 for 9"
124
121
15.7
5.2
4.2
16.7
3.4
14.7
5.7
3.2
5.5
@ 1 foot, OLDER ALLUVIUM: LEAN CLAY with SAND,
approximately 15% fine grained sand, 85% clayey fines of
low to medium plascitity, red brown, damp, some pinhole
porosity.
16
@ 5 feet, CLAYEY SAND with GRAVEL, approximately 15%
gravel to 2", 20% coarse grained sand, 20% medium grained
sand, 25% fine grained sand, 20% clayey fines of low
plasticity, red brown, damp.
B-1
@ 12 feet, difficult drilling
@ 15 feet, LEAN CLAY with SAND, approximately 5% coarse
grained sand, 10% medium grained sand, 15% fine grained
sand, 70% clayey fines of low plasticity, light red brown,
moist.
@ 20 feet, CLAYEY SAND with GRAVEL, approximately 30%
gravel to 3", 15% coarse grained sand, 15% medium grained
sand, 20% fine grained sand, 20% clayey fines of low
plasticity, red brown, dry.
@ 25 feet, some 2 to 3" thick LEAN CLAY with SAND layers,
increase in overal moisture content.
@ 30 feet, some 4 to 6" thick SILTY SAND with trace clay
layers , decrease in overall moisture content.
@ 35 feet, remains difficult to drill.
END OF BORING @ 41' due to refusal on gravel and possible
cobbles
Fil to 1'
No groundwater
No bedrock
@ 0 feet, 3/4" gravel with silt and some asphalt concrete debris.
111.0
117.4
112.0
113.8
108.7
CL
SC
CL
SC
24
68
11
37
77 @ 10 feet, increase in gravel to approximately 35% and to 3",
dry.SPT33616.1
DESCRIPTIONLABORATORY TESTSGEOTECHNICAL GROUP INC.BLOW COUNTSCLIENT:
February 4, 2020
C & C Development Co., LLC(%)MOISTURE CONTENT0
5
10
15
20
25
30
35
40
45
@ 2 feet, contains trace coarse and medium grained sand, no
visible porosity, moist.(PCF)1, 3, 4,
7, 8, 9,
10, 11
TEST DATA
LOG OF BORING B-1
Mobile B-61DRY DENSITYSAMPLE TYPEEQUIPMENT:
PROJECT NUMBER:
8"ENCLOSURE:HOLE DIA.:
Proposed Apartment ComplexU.S.C.S.DATE DRILLED:
ELEVATION:DEPTH IN FEETPROJECT:LITHOLOGY
@ 0.66 feet, OLDER ALLUVIUM: LEAN CLAY with SAND,
approximately 10% medium grained sand, 15% fine grained
sand, 75% clayey fines of low plasticity, red brown, damp.
90
51
15.9
4.7
6.2
5.3
17.4
16.1
3.1
1.4
13
@ 0.30 feet, AGGREGATE BASE, 0.33' thick.
16
@ 2 feet, becomes moist.
111.2
@ 7 feet, rings disturbed.
B-2
@ 15 feet, no visible porosity.
@ 19 feet, CLAYEY SAND with GRAVEL, approximately 30%
gravel to 3", 15% coarse grained sand, 15% medium grained
sand, 20% fine grained sand, 20% clayey fines of low
plasticity, red brown, dry.
@ 25 feet, rings disturbed, cobble in tip of sampler.
END OF BORING @ 25.5'
No fill
No groundwater
No bedrock
@ 0 feet, ASPHALT CONCRETE, 0.30' thick.
121.7
110.5
109.7
114.8
116.6
CL
SC
CL
SC
25
@ 12 feet, LEAN CLAY with SAND, trace coarse grained sand,
trace medium grained sand, 10% fine grained sand, 90%
clayey fines of low plasticity, red brown, moist, some pinhole
porosity.
10
23
22 LABORATORY TESTSDESCRIPTIONBLOW COUNTSGEOTECHNICAL GROUP INC.
CLIENT:
@ 5 feet, CLAYEY SAND with GRAVEL, approximately 25%
gravel to 3", 15% coarse grained sand, 15% medium grained
sand, 20% fine grained sand, 25% clayey fines of low
plasticity, red brown, damp.SPTFebruary 4, 2020MOISTURE CONTENT0
5
10
15
20
25
30
33616.1(%)LITHOLOGYTEST DATA
LOG OF BORING B-2
Mobile B-61
HOLE DIA.:DRY DENSITY(PCF)U.S.C.S.C & C Development Co., LLC
Proposed Apartment Complex PROJECT NUMBER:
8"SAMPLE TYPEENCLOSURE:
PROJECT:
EQUIPMENT:
DATE DRILLED:
ELEVATION:DEPTH IN FEET
@ 0 feet, ASPHALT CONCRETE GRINDINGS.
18
30
17
15
16
90
51 for 4"
17.4
15.9
7.1
7.0
16.8
4.1
111.7 @ 1 foot, ASPHALT CONCRETE GRINDINGS.
B-3
@ 5 feet, trace gravel to 1.5".
@ 7 feet, CLAYEY SAND with GRAVEL, approximately 25%
gravel to 2", 15% coarse grained sand, 15% medium grained
sand, 25% fine grained sand, 20% clayey fines of low
plasticity, red brown, damp.
@ 10 feet, WELL GRADED SAND layer, 0.25' thick.
@ 12 feet, LEAN CLAY with SAND, approximately 5%
medium grained sand, 10% fine grained sand, 85% clayey
fines of low plasticity, red brown, moist.
@ 20 feet, CLAYEY SAND with GRAVEL, approximtely 30%
gravel to 2", 15% coarse grained sand, 15% medium grained
sand, 20% fine grained sand, 20% clayey fines of low
plasticity, red brown, damp.
@ 25 feet, no recovery.
END OF BORING @ 26.33'
Fill to 2'
No groundwater
No bedrock
12.1
115.8
121.0
115.0
104.5
116.5
123.0
SM
CL
SC
SW
SC
CL
SC
17
@ 2 feet, OLDER ALLUVIUM: LEAN CLAY with SAND,
approximately 5% medium grained sand, 10% fine grained
sand, 85% clayey fines of low plasticity, red brown, moist.
CLIENT:
February 4, 2020
C & C Development Co., LLCLABORATORY TESTSBLOW COUNTS33616.1SPT(%)0
5
10
15
20
25
30 MOISTURE CONTENT@ 0.5 feet, FILL: SILTY SAND, approximately 25% coarse
grained sand, 25% medium grained sand, 25% fine grained
sand, 25% silty fines with trace clay, red brown, damp.(PCF)TEST DATA
LOG OF BORING B-3
Mobile B-61GEOTECHNICAL GROUP INC.DRY DENSITYDESCRIPTION
PROJECT NUMBER:
8"ENCLOSURE:
Proposed Apartment Complex
HOLE DIA.:
DATE DRILLED:SAMPLE TYPEELEVATION:DEPTH IN FEETPROJECT:LITHOLOGYU.S.C.S.EQUIPMENT:
END OF BORING @ 21.5'
Fill to 3'
No groundwater
No bedrock
15.1
16.3
11.9
3.9
4.6
9.6
@ 0 feet, ASPHALT CONCRETE GRINDINGS.
@ 1.5 feet, FILL: LEAN CLAY with SAND, approximately 10%
gravel to 1", 25% coarse grained sand, 25% medium grained
sand, 25% fine grained sand, 15% clayey fines of low
plasticity, gray brown.
@ 3 feet, OLDER ALLUVIUM: LEAN CLAY with SAND,
approximately 5% coarse grained sand, 10% medium
grained sand, 10% fine grained sand, 75% clayey fines of low
plasticity, red brown, moist, trace pinhole porosity.
@ 7 feet, CLAYEY SAND with GRAVEL, approximately 20%
gravel to 1.5", 15% coarse grained sand, 15% medium
grained sand, 15% fine grained sand, 35% clayey fines of low
plasticity, red brown, moist.
@ 18.5 feet, LEAN CLAY with SAND layer, approximately 5%
coarse grained sand, 10% medium grained sand, 15% fine
grained sand, 70% clayey fines of low plasticity, red brown,
damp.
46
114.1
B-4
9, 10, 11
TEST DATA
LOG OF BORING B-4
Mobile B-61
@ 10 feet, increase in gravel, rings disturbed, damp.
110.7
111.5
126.1
125.5
CL
SC
CL
SC46
52
17
19
44
February 4, 2020BLOW COUNTS(%)DESCRIPTIONMOISTURE CONTENTGEOTECHNICAL GROUP INC.LABORATORY TESTS0
5
10
15
20
25
33616.1
CLIENT:
HOLE DIA.:DRY DENSITY(PCF)SAMPLE TYPEU.S.C.S.LITHOLOGYPROJECT:SPTELEVATION:C & C Development Co., LLCDEPTH IN FEETDATE DRILLED:
PROJECT NUMBER:
8"ENCLOSURE:
Proposed Apartment Complex
EQUIPMENT:
TEST DATA
U.S.C.S.@ 7 feet, some gravel.
@ 10 feet, CLAYEY SAND with GRAVEL, approximately 25%
gravel to 3", 15% coarse grained sand, 15% medium grained
sand, 20% fine grained sand, 25% clayey fines of low
plasticity, red brown, dry, somewhat difficult drilling.
@ 15 feet, no recovery, cobble in tip of sampler.
END OF BORING @ 15.25'
Fill to 2'
No groundwater
No bedrock
@ 0.25 feet, FILL: SILTY SAND, approximately 15% coarse
grained sand, 25% medium grained sand, 25% fine grained
sand, 35% silty fines, black.
@ 0 feet, ASPHALT GRINDINGS.
LOG OF BORING B-5
Mobile B-61
128.3
B-5HOLE DIA.:DRY DENSITY(PCF)SAMPLE TYPE118.3
109.6
SM
CL
SC
@ 2 feet, OLDER ALLUVIUM: LEAN CLAY with SAND, trace
gravel to 1/2", approximately 5% coarse grained sand, 10%
medium grained sand, 10% fine grained sand, 75% clayey
fines of low plasticity, red brown, moist.
20
27
55
46 for 4"
15.3
13.0
4.1MOISTURE CONTENTLITHOLOGY33616.1(%)0
5
10
15
20
February 4, 2020
CLIENT:
GEOTECHNICAL GROUP INC.
DESCRIPTIONDEPTH IN FEETENCLOSURE:
EQUIPMENT:SPTDATE DRILLED:
Proposed Apartment Complex
ELEVATION:
8"
PROJECT:
C & C Development Co., LLCLABORATORY TESTSBLOW COUNTSPROJECT NUMBER:
DRY DENSITY4.4
@ 0 feet, ASPHALT GRINDINGS.
@ 0.33 feet, OLDER ALLUVIUM: CLAYEY SAND with
GRAVEL, approximately 25% gravel to 2",15% coarse
grained sand, 15% medium grained sand, 25% fine grained
sand, 20% clayey fines of low plasticity, red brown, damp.
@ 15 feet, LEAN CLAY with SAND, approximately 5% coarse
grained sand, 10% medium grained sand, 15% fine grained
sand, 70% clayey fines of low plasticity, red brown, moist.
@ 20 feet, SANDY SILT, approximately 40% fine grained sand,
60% silty fines with trace clay.
@ 25 feet, some gravel, dry.
END OF BORING @ 25.5'
No fill
No groundwater
No bedrock
17.2
4.9
SC
B-6
LOG OF BORING B-6
Mobile B-61
HOLE DIA.:
CL
ML15.3
TEST DATA
40
30
53
13
20
73
5.0
6.0 (%)MOISTURE CONTENT0
5
10
15
20
25
30 (PCF)7SPT
33616.1
February 4, 2020
CLIENT:
GEOTECHNICAL GROUP INC.
DESCRIPTIONLITHOLOGY
ELEVATION:
DATE DRILLED:DEPTH IN FEETBLOW COUNTSProposed Apartment ComplexPROJECT:
ENCLOSURE:
EQUIPMENT:U.S.C.S.LABORATORY TESTSC & C Development Co., LLC
PROJECT NUMBER:
8"SAMPLE TYPE
APPENDIX C
Laboratory Testing Program and Test Results
LOR GEOTECHNICAL GROUP, INC.
APPENDIX C
LABORATORY TESTING
General
Selected soil samples obtained from our borings were tested in our geotechnical laboratory
to evaluate the physical properties of the soils affecting foundation design and construction
procedures. The laboratory testing program performed in conjunction with our investigation
included in-place moisture content and dry density, laboratory compaction characteristics,
direct shear, sieve analysis, sand equivalent, R-value, expansion index, Atterberg limits,
and soluble sulfate content. Descriptions of the laboratory tests are presented in the
following paragraphs:
Moisture Density Tests
The moisture content and dry density information provides an indirect measure of soil
consistency for each stratum, and can also provide a correlation between soils on this site.
The dry unit weight and field moisture content were determined for selected undisturbed
samples, in accordance with ASTM D 2922 and ASTM D 2216, respectively, and the
results are shown on the Boring Logs, Enclosures B-1 through B-6 for convenient
correlation with the soil profile.
Laboratory Compaction
Selected soil samples were tested in the laboratory to determine compaction
characteristics using the ASTM D 1557 compaction test method. The results are presented
in the following table:
LABORATORY COMPACTION
Boring
Number
Sample
Depth
(feet)
Soil Description
(U.S.G.S.)
Maximum
Dry Density
(pcf)
Optimum
Moisture
Content
(percent)
B-1 1-4 (CL) Lean Clay with Sand 126.5 11.0
B-6 6-9 (SC) Clayey Sand 134.5 6.5
C
LOR GEOTECHNICAL GROUP, INC.
Direct Shear Tests
Shear tests are performed with a direct shear machine in general accordance with ASTM
D 3080 at a constant rate-of-strain (usually 0.04 inches/minute). The machine is designed
to test a sample partially extruded from a sample ring in single shear. Samples are tested
at varying normal loads in order to evaluate the shear strength parameters, angle of
internal friction and cohesion. Samples are tested in a remolded condition (90 percent
relative compaction per ASTM D 1557) and soaked, to represent the worst case conditions
expected in the field.
The results of the shear tests are presented in the following table:
DIRECT SHEAR TESTS
Boring
Number
Sample Depth
(feet)
Soil Description
(U.S.G.S.)
Angle of
Internal Friction
(degrees)
Apparent
Cohesion
(psf)
B-1 1-4 (CL) Lean Clay with Sand 31 700
Sieve Analysis
A quantitative determination of the grain size distribution was performed for selected
samples in accordance with the ASTM D 422 laboratory test procedure. The determination
is performed by passing the soil through a series of sieves, and recording the weights of
retained particles on each screen. The results of the sieve analyses are presented
graphically on Enclosure C-1.
Sand Equivalent
The sand equivalent of selected soils were evaluated using the California Sand Equivalent
Test Method, Caltrans Number 217. The results of the sand equivalent tests are presented
with the grain size distribution analyses on Enclosure C-1.
R-Value Test
Soil samples were obtained at probable pavement subgrade level and was tested to
determine its R-value using the California R-Value Test Method, Caltrans Number 301. The
results of the R-value test is presented on Enclosure C-1.
C
LOR GEOTECHNICAL GROUP, INC.
Expansion Index Tests
Remolded samples are tested to determine their expansion potential in accordance with
the Expansion Index (EI) test. The test is performed in accordance with the Uniform
Building Code Standard 18-2. The test results are presented in the following table:
EXPANSION INDEX TESTS
Boring
Number
Sample
Depth
(feet)
Soil Description
(U.S.C.S.)
Expansion
Index
(EI)
Expansion
Potential
B-1 1-4 (CL) Lean Clay with Sand 56 Medium
Expansion Index: 0-20 21-50 51-90 91-130
Expansion Potential: Very low Low Medium High
Atterberg Limits
Selected samples of the fine-grained soil units encountered at the site are tested for their
Atterberg limits in accordance with ASTM D 4318. The results of these tests are presented
on Enclosure C-2.
Soluble Sulfate Content Tests
The soluble sulfate content of selected subgrade soils was evaluated and the
concentration of soluble sulfates in the soils was determined by measuring the optical
density of a barium sulfate precipitate. The precipitate results from a reaction of barium
chloride with water extractions from the soil samples. The measured optical density is
correlated with readings on precipitates of known sulfate concentrations. The test results
are presented on the following table:
C
LOR GEOTECHNICAL GROUP, INC.
SOLUBLE SULFATE CONTENT TESTS
Boring
Number
Sample Depth
(feet)
Soil Description
(U.S.G.S.)
Sulfate
Content
(percent by
weight)
B-1 1-4 (CL) Lean Clay with Sand < 0.005
B-4 3-6 (SC) Clayey Sand < 0.005
LOR GEOTECHNICAL GROUP, INC.
C
1003/8 70 140
D30
30
0
20
40
50
60
70
80
90
10
100
0.0010.010.1110100
11.1
16 20 30 50640
COBBLES
3
16.7
SILT OR CLAY
18
B-1
B-4
@ 1-4 ft
@ 3-6 ft
4
DATE
%Clay
RV
HYDROMETER
ENCLOSURE C-1
Proposed Apartment Complex
D10
PROJECT NO.33616.1
2/17/20
PROJECT
%Silt%Sand
8 10 14
(CL) Lean Clay with Sand
(CL) Lean Clay with Sand
RV
4.2
7.9
GRADATION CURVES
GRAVEL
D60
P
E
R
C
E
N
T
F
I
N
E
R
B
Y
W
E
I
G
H
T
GRAIN SIZE IN MILLIMETERS
finemediumcoarse
SAND
6
79.1
81.0
200
U.S. SIEVE NUMBERS
fine
B-1
B-4
SE
U.S. SIEVE OPENING IN INCHES
1/2
coarse
4 3 2 1.5 3/4
5
Specimen Identification
Specimen Identification
Cc Cu
D100
LOR Geotechnical Group, Inc.
1
25.40
%Gravel
PL PI
@ 1-4 ft 19.00
16
Soil Classification
3
3
--
@ 3-6 ft
0
10
20
30
40
50
60
0 20 40 60 80 100
CH
MH
LIQUID LIMIT (LL)
B-1 34 16 18 79.1@ 1-4 ft
ATTERBERG LIMITS' RESULTS
CL-ML
Project:Project No.:
Date:
33616.1
2/17/20
Proposed Apartment Complex
ENCLOSURE: C - 2LOR Geotechnical Group, Inc.
(CL) Lean Clay with Sand
ML
CL
Specimen Identification LL PL PI Fines Classification
P
L
A
S
T
I
C
I
T
Y
I
N
D
E
X
APPENDIX D
Seismic Design Spectra
LOR GEOTECHNICAL GROUP, INC.
Project:APN 375-291-14
Project Number:33616.1
Client:C & C Development
Site Lat/Long;33.8070/-117.8575
Controlling Seismic Source:Puente Hills
REFERENCE NOTATION VALUE REFERENCE NOTATION VALUE
Site Class A, B, C, D, E or F D (Site Class D (Measured) only)Fv (Table 11.4-2)[Used for General Spectrum]Fv 1.8
Site Class D - 21.2.2.(ii)Fa 1 Design Maps SMS 1.412
Site Class D - 21.2.2.(ii)Fv 2.5 Design Maps SDS 0.941
0.2*(SD1/SDS)T0 0.127 Design Maps S1 0.501
SD1/SDS TS 0.637 Design Maps FPGA 1.1
Fundamental Period (12.8.2)T Period Design Maps PGA 0.593
Seismic Design Maps or Fig 22-14 TL 8 Equation 11.8-1 PGAM 0.652
2/3*SM1 SD1 0.599 Section 21.5.3 80% of PGAM 0.522
FV*S1 SM1 0.899 Design Maps CR1 0.923
Design Maps Crs 0.926
Cr - At Perods <=0.2, Cr=CRS Cr 0.926
Cr - At Periods >=1.0, Cr=Cr1 Cr 0.923
Cr - At Periods between 0.2 and 1.0 Period Cr
use trendline formula to complete 0.200 0.926
0.300 0.926
0.400 0.925
0.500 0.925
0.600 0.925
0.680 0.924
1.000 0.923
RISK COEFFICIENT
y = -0.0038x + 0.9268
0.9225
0.923
0.9235
0.924
0.9245
0.925
0.9255
0.926
0.9265
0.000 0.200 0.400 0.600 0.800 1.000 1.200
Cr Interpolation 0.2 to 1.0
LOR Geotechnical Group, Inc.
0.005 0.74 0.70 0.76 0.73 0.926 0.679
0.020 0.75 0.70 0.77 0.74 0.926 0.688
0.030 0.78 0.73 0.81 0.77 0.926 0.716
0.040 0.82 0.78 0.85 0.82 0.926 0.758
0.050 0.85 0.83 0.92 0.86 0.926 0.801
0.060 0.93 0.91 0.99 0.94 0.926 0.871
0.080 1.06 1.05 1.12 1.08 0.926 0.998
0.090 1.13 1.12 1.19 1.15 0.926 1.060
0.100 1.19 1.19 1.25 1.21 0.926 1.120
0.120 1.29 1.29 1.38 1.32 0.926 1.220
0.136 1.36 1.36 1.45 1.39 0.926 1.289
0.200 1.51 1.49 1.58 1.53 0.926 1.416
0.300 1.54 1.43 1.54 1.50 0.926 1.392
0.400 1.48 1.33 1.42 1.41 0.925 1.306
0.500 1.45 1.26 1.30 1.34 0.925 1.241
0.600 1.35 1.18 1.20 1.25 0.925 1.157
0.680 1.30 1.13 1.15 1.20 0.924 1.105
1.000 1.04 0.97 0.97 1.00 0.923 0.919
1.200 0.90 0.84 0.83 0.86 0.923 0.794
2.000 0.59 0.57 0.51 0.56 0.923 0.515
3.000 0.40 0.39 0.33 0.38 0.923 0.348
4.000 0.30 0.30 0.24 0.28 0.923 0.260
5.000 0.25 0.27 0.18 0.24 0.923 0.217
B-A - Boore-Atkinson (2008) NGA USGS 2008 MRC 0.679
C-B - Campbell-Bozorgnia (2008) NGA USGS 2008 MRC
C-Y - Chiou-Youngs (2007) NGA USGS 2008 MRC
Project No:33616.1
Probabilistic PGA:
PROBABILISTIC SPECTRA
2% in 50 year Exceedence
B - A C - B C - Y Mean Risk Coefficient
(CR)
Probabilistic
MCEPeriod
LOR Geotechnical Group, Inc.
33616.1Project No:
0.00
0.50
1.00
1.50
2.00
0.000 1.000 2.000 3.000 4.000 5.000 Acceleration (g) Period (seconds)
PROBABILISTIC MCER
SPECTRAL RESPONSE ACCELERATIONS
Boore-Atkinson (2008) NGA USGS 2008 MRC
Campbell - Bozorgnia (2008) NGA USGS 2008 MRC
Chiou-Youngs (2007) NGA USGS 2008 MRC
Probabilistic MCE
Analysis Information
Spectral Response @ 5 % Damping
with Maximum Rotated
Component.
Probability of Exceedence:
2% in 50 years
LOR Geotechnical Group, Inc.
Puente Hills
0.005 0.646 0.623 0.646
0.020 0.655 0.692 0.692
0.030 0.680 0.739 0.739
0.040 0.714 0.785 0.785
0.050 0.748 0.831 0.831
0.060 0.803 0.877 0.877
0.080 0.915 0.970 0.970
0.090 0.974 1.016 1.016
0.100 1.032 1.062 1.062
0.120 1.129 1.154 1.154
0.136 1.196 1.228 1.228
0.200 1.358 1.500 1.500
0.300 1.392 1.500 1.500
0.400 1.376 1.500 1.500
0.500 1.334 1.500 1.500
0.600 1.241 1.500 1.500
0.680 1.179 1.500 1.500
1.000 1.030 1.500 1.500
1.200 0.941 1.250 1.250
2.000 0.678 0.750 0.750
3.000 0.499 0.500 0.500
4.000 0.381 0.375 0.381
5.000 0.309 0.300 0.309
Deterministic PGA:0.646
Boore - Atkinson (2008) NGA USGS 2008 MRC
Campbell - Bozorgnia (2008) NGA USGS 2008 MRC
Chiou - Youngs (2007) NGA USGS 2008 MRC Project No:33616.1
*Attenuation Equations
DETERMINISTIC SPECTRUM AND LOWER LIMIT
Largest Amplitudes of Ground Motions Considering All Sources Calculated using Weighted Mean of Attenuation Equations*.
DETERMINISTIC
LOWER LIMIT
DETERMINISTIC
MCE 84 FRACTILE
DETERMINISTIC
(RAW)Period
Controlling Source:
LOR Geotechnical Group, Inc.
33616.1Project No:
0.00
0.50
1.00
1.50
2.00
0.000 1.000 2.000 3.000 4.000 5.000 Acceleration (g) Period (seconds)
DETERMINISTIC MCER
SPECTRAL RESPONSE ACCELERATIONS Deterministic Lower Limit
Deterministic (Raw)
Deterministic MCE
LOR Geotechnical Group, Inc.
0.005 0.679 0.646 0.646 0.430 0.005 0.399 0.319
0.020 0.688 0.692 0.688 0.459 0.010 0.421 0.337
0.030 0.716 0.739 0.716 0.478 0.030 0.509 0.408
0.040 0.758 0.785 0.758 0.505 0.040 0.554 0.443
0.050 0.801 0.831 0.801 0.534 0.050 0.598 0.478
0.060 0.871 0.877 0.871 0.581 0.060 0.642 0.514
0.080 0.998 0.970 0.970 0.646 0.080 0.731 0.585
0.090 1.060 1.016 1.016 0.677 0.090 0.775 0.620
0.100 1.120 1.062 1.062 0.708 0.100 0.820 0.656
0.120 1.220 1.154 1.154 0.770 0.110 0.864 0.691
0.136 1.289 1.228 1.228 0.819 0.120 0.908 0.727
0.200 1.416 1.500 1.416 0.944 0.136 0.941 0.753
0.300 1.392 1.500 1.392 0.928 0.150 0.941 0.753
0.400 1.306 1.500 1.306 0.870 0.160 0.941 0.753
0.500 1.241 1.500 1.241 0.827 0.170 0.941 0.753
0.600 1.157 1.500 1.157 0.771 0.180 0.941 0.753
0.680 1.105 1.500 1.105 0.737 0.190 0.941 0.753
1.000 0.919 1.500 0.919 0.613 0.200 0.941 0.753
1.200 0.794 1.250 0.794 0.529 0.300 0.941 0.753
2.000 0.515 0.750 0.515 0.343 0.400 0.941 0.753
3.000 0.348 0.500 0.348 0.232 0.500 0.941 0.753
4.000 0.260 0.381 0.260 0.174 0.600 0.941 0.753
5.000 0.217 0.309 0.217 0.145 0.640 0.936 0.749
0.680 0.881 0.705
0.850 0.705 0.564
Calculated Design 0.900 0.666 0.533
Value Value 0.950 0.631 0.505
SDS:0.850 0.850 1.000 0.599 0.479
SD1:0.724 0.724 1.200 0.499 0.400
SMS:1.274 1.274 2.000 0.300 0.240
SM1:1.086 1.086 3.000 0.200 0.160
4.000 0.150 0.120
Site Specfic MCEg:0.646 5.000 0.120 0.096
Site Class:D - measured
Project No:33616.1
ASCE 7-16: Section 21.4
SITE SPECIFIC SPECTRA
Probabilistic
MCE
Deterministic
MCEPeriod Site-Specific
MCE Period 80% General
Response Spectrum
ASCE 7 SECTION 11.4.6
General SpectrumDesign Response
Spectrum (Sa)
LOR Geotechnical Group, Inc.
33616.1Project No:
0.00
0.50
1.00
1.50
2.00
0.000 1.000 2.000 3.000 4.000 5.000 Acceleration (g) Period (seconds)
SPECTRAL RESPONSE ACCELERATIONS Probabilistic MCE
Deterministic MCE
Site-Specific MCE
Design Response Spectrum
ASCE 7 Section 11.4.6 General Spectrum
80% General Response Spectrum
LOR Geotechnical Group, Inc.