Appendix B - 8449 Garvey Soil ReportCal Land Engineering, Inc.
dba Quartech Consultants
Geotechnical, Environmental, and Civil Engineering
576 E. Lambert Road, Brea, California 92821; Tel: 714-671-1050; Fax: 714-671-1090
April 4, 2017
Hawaii Property, Inc.
120 East Valley Boulevard
San Gabriel, California 91776
Attention: Mr. Gerard Ngo
Subject: Report of Geotechnical Engineering Investigation, Proposed 4-Story Mixed Use
Building with one Level of Subterraneous Garage, 8449 Garvey Avenue, APN:
5288-004-057 and 3014 Earle Avenue APN: 5288-004-041, Rosemead,
California QCI Project No.: 16-087-001GE
Gentlemen:
In accordance with your request, Quartech Consultants (QCI) is pleased to submit this
Geotechnical Engineering Report for the subject site. The purpose of this report was to evaluate
the subsurface conditions and provide recommendations for foundation designs and other
relevant parameters of the proposed construction.
Based on the findings and observations during our investigation, the proposed construction of
the subject site for the intended use is considered feasible from the geotechnical engineering
viewpoints, provided that specific recommendations set forth herein are followed.
This opportunity to be of service is sincerely appreciated. If you have any questions pertaining
to this report, please call the undersigned.
Respectfully submitted,
Cal Land Engineering, Inc. (CLE)
dba Quartech Consultants (QCI)
___
Jack C. Lee, GE 2153 Keith Au
Principal Project Engineer
______________________
Abe Kazemzadeh
Dist: (4) Addressee
REPORT OF GEOTECHNICAL ENGINEERING
INVESTIGATION
Proposed Mixed Use Development
At
8449 Garvey Avenue
And 3014 Earle Avenue
APN: 5288-004-057 & 041
Rosemead, California
Prepared by
QUARTECH CONSULTANTS (QCI)
Project No.: 16-087-001GE
April 4, 2017
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QCI Project No.: 16-087-001GE April 4, 2017
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TABLE OF CONTENTS
1.0 INTRODUCTION .....................................................................................................................3
1.1 PURPOSE................................................................................................................................3
1.2 SCOPE OF SERVICES...............................................................................................................3
1.3 PROPOSED CONSTRUCTION ....................................................................................................3
1.4 SITE LOCATION .......................................................................................................................3
2.0 SUBSURFACE EXPLORATION AND LABORATORY TESTING .........................................4
2.1 SUBSURFACE EXPLORATION....................................................................................................4
2.2 LABORATORY TESTING ............................................................................................................4
3.0 SUMMARY OF GEOTECHNICAL CONDITIONS...................................................................4
3.1 SOIL CONDITIONS ...................................................................................................................4
3.2 GROUNDWATER ......................................................................................................................5
4.0 SEISMICITY.............................................................................................................................5
4.1 FAULTING ...............................................................................................................................5
4.2 SEISMICITY .............................................................................................................................5
4.3 ESTIMATED EARTHQUAKE GROUND MOTIONS ..........................................................................6
5.0 SEISMIC HAZARDS................................................................................................................6
5.1 LIQUEFACTION ........................................................................................................................6
5.2 EARTHQUAKE INDUCED SETTLEMENT.......................................................................................7
5.3 LANDSLIDING ..........................................................................................................................8
5.4 LURCHING...............................................................................................................................8
5.5 SURFACE RUPTURE ................................................................................................................8
5.6 GROUND SHAKING ..................................................................................................................8
5.7 CITY OF ROSEMEAD FAULT HAZARD MANAGEMENT ZONES (HFMZ) .........................................8
6.0 CONCLUSIONS ......................................................................................................................8
6.1 SEISMICITY .............................................................................................................................9
6.2 SEISMIC INDUCED HAZARDS ....................................................................................................9
6.3 EXCAVATABILITY .....................................................................................................................9
6.4 SURFICIAL SOIL REMOVAL AND RECOMPACTION.......................................................................9
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6.5 GROUNDWATER ......................................................................................................................9
7.0 RECOMMENDATIONS ...........................................................................................................9
7.1 GRADING ................................................................................................................................9
7.1.1 Site Preparation..............................................................................................................9
7.1.2 Surficial Soil Removals.................................................................................................10
7.1.3 Treatment of Removal Bottoms....................................................................................10
7.1.4 Structural Backfill..........................................................................................................10
7.2 BASEMENT EXCAVATION........................................................................................................10
7.2.1 Sloping Excavation.......................................................................................................10
7.2.2 Shoring .........................................................................................................................11
7.3 FOUNDATION DESIGN............................................................................................................11
7.3.1 Conventional Foundation (Building)..............................................................................11
7.3.3 Settlement.....................................................................................................................12
7.3.4 Lateral Pressures..........................................................................................................12
7.3.5 Wall Seismic Loading ...................................................................................................12
7.3.6 Wall Drainage...............................................................................................................13
7.4 FOUNDATION CONSTRUCTION................................................................................................13
7.5 CONCRETE SLAB...................................................................................................................13
7.6 TEMPORARY EXCAVATION AND BACKFILL...............................................................................14
8.0 INSPECTION.........................................................................................................................14
9.0 CORROSION POTENTIAL ...................................................................................................14
10.0 SEISMIC DESIGN ...............................................................................................................15
11.0 PLAN REVIEW....................................................................................................................15
12.0 COUNTY OF LOS ANGELES 111 STATEMENT...............................................................15
13.0 REMARKS...........................................................................................................................16
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1.0 INTRODUCTION
1.1 Purpose
This report presents a summary of our preliminary geotechnical engineering investigation for the
proposed construction at the subject site. The purposes of this investigation were to evaluate the
subsurface conditions at the area of proposed construction and to provide recommendations
pertinent to grading, foundation design and other relevant parameters of the development.
1.2 Scope of Services
Our scope of services included:
• Review of available soil engineering data of the area.
• Subsurface exploration consisting of logging and sampling of two 8-inch diameter hollow stem
auger borings to a maximum depth of 51.5 feet below the existing grade at the subject site.
The exploration was logged by a QCI engineer. Boring logs are presented in Appendix A.
• Laboratory testing of representative samples to establish engineering characteristics of the
on-site soil. The laboratory test results are presented in Appendices A and B.
• Engineering analyses of the geotechnical data obtained from our background studies, field
investigation, and laboratory testing.
• Preparation of this report presenting our findings, conclusions, and recommendations for the
proposed construction.
1.3 Proposed Construction
Based on the provided information, it is our understanding that the subject site will be developed
for construction of a commercial and residential mixed used building. The main structure of the
building is anticipated to be four stories in height above the ground level with one level of
subterranean garage. The lowest garage floor will be approximately 9-11 feet below the existing
ground surface. The subterranean garage will occupy the entire building site. Column loads are
unknown at this time, but are expected to be medium. Minor cut and fill grading operation is
anticipated to reach the desired grades.
1.4 Site Location
The project site is located at the northwest corner of Garvey Avenue and Earle Avenue, relatively
short distance east of Willard Avenue in the City of Rosemead, California. The lot is
approximately 37,810 square feet (0.868 acres) and proposed construction is for a mixed-use
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building at the subject site. The approximate regional location is shown on the attached Site
Location Map (Figure 1). Topographically, the subject site is relatively flat. No major surface
erosions were observed at the time of our field investigation. Detail configuration of the site is
presented in the attached Site Plan, Figure 2.
2.0 SUBSURFACE EXPLORATION AND LABORATORY TESTING
2.1 Subsurface Exploration
Our subsurface exploration consisted of drilling two 8-inch diameter hollow stem borings to a
maximum depth of 51.5 feet at the locations shown on the attached Site Plan, Figure 2. The
purpose of the explorations was to assess the engineering characteristics of the onsite soils with
respect to the proposed development.
The borings were logged by a representative of this office. Relatively undisturbed and bulk
samples were collected during drilling for laboratory testing. Natural soil was encountered in the
borings to the depths explored. Boring logs are presented in Appendix A.
2.2 Laboratory Testing
Representative samples were tested for the following parameters: in-situ moisture content and
density, consolidation, direct shear strength, expansion, percent fines, Atterberg limits and
corrosion potential. Results of our laboratory testing along with a summary of the testing
procedures are presented in Appendix B. In-situ moisture and density test results are presented
on the boring logs in Appendix A.
3.0 SUMMARY OF GEOTECHNICAL CONDITIONS
3.1 Soil Conditions
The onsite near surface soils consist predominantly fine-grained silty sand (SM) and. In general,
these soils exist in medium dense and slightly moist conditions. Underlying the surface soils, fine
to medium-grained silty sand (SM), and sandy silt to clayey silt (ML) were disclosed in the borings
to the depths explored (51.5 feet below the existing ground surface). These soils exist in the
medium dense to very dense and hard, and slightly moist to very moist conditions. The soils
become denser as depth increases.
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3.2 Groundwater
Ground water level was not encountered to the depth explored (approximately 51.5 feet below the
existing grade) during our subsurface investigation. In our opinion, groundwater will not be a
problem during the near surface construction.
Based on our review of the “Historically Highest Ground Water Contours and Borehole Log Data
Locations, El Monte Quadrangle”, by CGS (formerly CDMG), it is estimated that the highest
historical ground water level is approximately 5 to 10 feet below the existing grade. It should be
noted that the CDMG ground water map is obtained by evaluating technical publications,
geotechnical borehole data, water-well logs dating back to the “turn-of-the-century”. This report
also indicated that ground water levels in the areas from 1960-1997 data are generally 5 to 50
feet deeper than the earlier measured data. No specific date was provided pertaining to the high
ground water level.
4.0 SEISMICITY
4.1 Faulting
Based on our study, there are no known active faults crossing the property. The nearest known
active regional fault is Upper Elysian Park Fault zones located 1.0 mile from the site.
4.2 Seismicity
The subject site is located in Southern California, which is a tectonically active area. The type and
magnitude of seismic hazards affecting the site depend on the distance to causative faults, the
intensity, and the magnitude of the seismic event. Table 1 indicates the distance of the fault zones
and the associated maximum magnitude earthquake that can be produced by nearby seismic
events. As indicated in Table 1, the Upper Elysian Park fault zones are considered to have the
most significant effect to the site from a design standpoint.
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TABLE 1
Characteristics and Estimated Earthquakes for Regional Faults
Fault Name Approximate Distance to
Site (mile)
Maximum Magnitude
Earthquake (Mw)
Elysian Park (Upper) 1.0 6.7
Raymond 4.4 6.8
Verdugo 4.9 6.9
Elsinore 5.1 7.8
Verdugo 6.2 6.9
Puente Hills (LA) 6.9 7.0
Sierra Madre 7.8 7.3
Hollywood 9.2 6.7
Clamshell-Sawpit 9.3 6.7
Puente Hills (Santa Fe Springs) 9.8 6.7
San Jose 11.9 6.7
Santa Monica Conn. Alt. 2 11.9 7.4
Puente Hills (Coyote Hills) 12.0 6.9
Newport Inglewood Conn. Alt. 2 15.3 7.5
Newport Inglewood Conn. Alt. 1 15.6 7.5
Santa Monica Conn. Alt. 1 18.8 7.3
Sierra Madre (San Fernando) 19.2 6.7
Chino Alt. 2 19.5 6.8
Chino Alt. 1 19.6 6.7
Cucamonga 20.8 6.7
Reference: 2008 National Seismic Hazard Maps - Source Parameters
4.3 Estimated Earthquake Ground Motions
In order to estimate the seismic ground motions at the subject site, QCI has utilized the seismic
hazard map published by California Geological Survey. According to this report, the peak ground
alluvium acceleration at the subject site for a 2% and 10% probability of exceedance in 50 years
is about 0.867g and 0.519g, respectively (NSHM 2014, 2008 Deaggregation of Seismic
Hazards). Peak ground acceleration (PGAM), corresponding to USGS Design Map Summary
Report, 2015 NEHRP Provision, (CBC 2016), site class D(default) is 1.006g.
5.0 SEISMIC HAZARDS
5.1 Liquefaction
Liquefaction is the transformation of a granular material from a solid to a liquid state as a result of
increasing pore-water pressure. The material will then loses strength and can flow if unrestrained,
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thus leading to ground failure. Liquefaction can be triggered in saturated cohesionless material by
short-term cyclic loading, such as shaking due to an earthquake. Ground failure that results from
liquefaction can be manifested as flow landsliding, lateral spread, loss of bearing capacity, or
settlement.
The potential for liquefaction at the site’s sandy soil was evaluated using the computer program
“LIQUEFY2” by Thomas Blake, the subsurface data from Boring B-1, the design earthquake (M
=7.0), and ground acceleration of 0.867g (2% probability of exceedance in 50 years). The total unit
weight used for the onsite soils is 120 pcf. The calculated ground water level is raised to the depth
of 5 feet below the existing ground surface. Conversion from California modified split spoon to field
SPT blow counts is 0.7 (County of L.A. GS045.0 October 1, 2014). Based on the analyses
presented on the enclosed Appendix C indicated that the factor of safety is less than 1.30 for the
onsite soils at the depth of 37 to 42 feet.
Based on the laboratory test results on clayey soils, for B-1 @ 45 feet and @ 50 feet, the
saturated moisture content of the encountered clayey soils is less than 85 percent of liquid limit
with PI less than 12 (Bray and Sancio 2006, if PI is less than 12 and wc/LL is less than 0.85, the
clayey soil is not susceptible to liquefaction). According to procedures referenced in SP117A,
(Guideline for Evaluating and Mitigating Seismic Hazards in California), our laboratory Atterberg
Limits and saturated moisture content of clayey soils material, it is our opinion that the encountered
clayey soil is not susceptible to liquefaction.
5.2 Earthquake Induced Settlement
The sandy soils tend to settle and densify when they are subjected to earthquake shaking.
Should the sand be saturated and there is no possibility for drainage so that constant volume
conditions are maintained, the primary effect of the shaking is the generation of excess pore
water pressures. Settlement then occurs as the excess pore pressures dissipate. The primary
factors controlling seismic induced settlement are the cyclic stress ratio, maximum shear strain
induced by earthquake, the strength and density of the sand, and the magnitude of the
earthquake. Based on the procedures developed by Tokimatsu and Seed on 1987, it is our
opinion that seismic induced total settlement and deferential settlement of saturated sand is 0.42
inches and 0.21 inches respectively.
.
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5.3 Landsliding
A potential for landsliding is often suggested in areas of moderate to steep terrain that is
underlain by weak or un-favorably oriented geological conditions. Neither of these conditions
exists at the site. Due to the relatively flat nature of the site, it is our opinion that the potential for
landslide is remote.
5.4 Lurching
Soil lurching refers to the rolling motion on the surface due to the passage of seismic surface
waves. Effects of this nature are not considered significant on the subject site where the thickness
of alluvium does not vary appreciably under structures.
5.5 Surface Rupture
Surface rupture is a break in the ground surface during or as a consequence of seismic activity.
The potential for surface rupture on the subject site is considered low due to the absence of known
active faults at the site.
5.6 Ground Shaking
Throughout southern California, ground shaking, as a result of earthquakes, is a constant
potential hazard. The relative potential for damage from this hazard is a function of the type and
magnitude of earthquake events and the distance of the subject site from the event. Accordingly,
proposed structures should be designed and constructed in accordance with applicable portions
of the building code.
5.7 City of Rosemead Fault Hazard Management Zones (HFMZ)
The site is not located within the designated City of Rosemead Safety Element as shown on Plate
1a City of Rosemead Fault Hazard Management Zones (FHMZ). Based on examining the
exploratory borings, B-1 and B-2 and nearby site’s exploratory borings, it was determined that the
soil borings are similar and there is no indication of a fault related discontinuity within the site
underlying soil materials
6.0 CONCLUSIONS
Based on our subsurface investigation, it is our opinion that the proposed construction is feasible
from a geotechnical standpoint, provided the recommendations contained herein are incorporated
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in the design and construction. The following is a summary of the geotechnical design and
construction factors that may affect the development of the site:
6.1 Seismicity
Based on our studies on seismicity, there are no known active faults crossing the property.
However, the site is located in a seismically active region and is subject to seismically induced
ground shaking from nearby and distant faults, which is a characteristic of all Southern California.
6.2 Seismic Induced Hazards
Based on our field investigation, laboratory testing and liquefaction analysis, the factor of safety is
less than 1.30 for the onsite soils at the depth of 37 to 42 feet.
6.3 Excavatability
Based on our subsurface investigation, excavation of the subsurface materials should be
accomplished with conventional earthwork equipment.
6.4 Surficial Soil Removal and Recompaction
Based on our investigation, it is concluded that the existing surficial soils may not be suitable for
structure support as they presently exist and will require remedial grading as discussed herein.
6.5 Groundwater
Groundwater was not encountered during our field exploration. Groundwater is not anticipated to
be encountered during the near surface construction.
7.0 RECOMMENDATIONS
Based on the subsurface conditions exposed during field investigation and laboratory testing
program, it is recommended that the following recommendations be incorporated in the design
and construction phases of the project.
7.1 Grading
7.1.1 Site Preparation
Prior to initiating grading operations, any existing vegetation, trash, debris, over-sized materials
(greater than 8 inches), and other deleterious materials within construction areas should be
removed from the subject site.
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7.1.2 Surficial Soil Removals
It is QCI's opinion that no additional removal will be necessary within the basement cut areas.
However, it is recommended that the cut areas be cut to grade then observed by a representative
of this office to verify the sub-grade soil conditions for any potential needs for removal of loose
soils and replacement with compacted fill. This may also be necessary due to difference in
expansion characteristics of foundation materials beneath a structure.
7.1.3 Treatment of Removal Bottoms
Soils exposed within areas approved for fill placement should be scarified to a depth of 6 to 10
inches, conditioned to near optimum moisture content, then compacted in-place to minimum
project standards.
7.1.4 Structural Backfill
The onsite soils may be used as compacted fill provided they are free of organic materials and
debris. Fills should be placed in relatively thin lifts (6 to 8 inches), brought to near optimum
moisture content, and then compacted to at least 90 percent relative compaction based on
laboratory standard ASTM D-1557-12.
7.2 Basement Excavation
The required excavation for the proposed subterranean garage will extend to a maximum of
approximately 9 to 11 feet below the existing ground surface. The criteria for sloped excavations
and/or shoring method for the alignments required vertical cuts, depends on many factors, which
include depth of excavation, soil conditions, types of shoring, distance to the existing structures or
public improvement, consequences of potential ground movement, and construction procedures.
7.2.1 Sloping Excavation
Should the space be available at the site, the required excavation may be made with sloping
banks. Based on materials encountered in the test borings, it is our opinion that sloped
excavations may be made no steeper than 1 to 1 (horizontal to vertical) for the underlying native
soils. Flatter slope cuts may be required if loose soils encountered during excavation. No heavy
construction vehicles, equipment, nor surcharge loading should be permitted at the top of the
slope. A representative of this office should inspect the temporary excavation to make any
necessary modifications or recommendations.
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7.2.2 Shoring
Shoring will be required for temporary excavation made vertically or near vertically of more than 5
feet. An active earth pressure of 35 pound per cubic foot may be used for the temporary
cantilever shoring system. Any surcharged loads resulting from the adjacent building or the traffic
in the adjacent street or alley should be considered as an added load to the above
recommended. The upper 10 feet of the shoring is recommended to be designed to resist an
additional pressure of 200 pounds per square ft. resulting from the traffic in the adjacent street.
Soldier piles or beams should be spaced at the required distance specified by the project
structural/shoring engineer. Lagging may be required to span between soldier piles to support the
lateral earth pressure.
The shoring and bracing should be designed and constructed in accordance with current
requirements of CAL/OSHA and all other public agencies having jurisdiction. Careful examination
of the soil excavation and inspection of on-site installation of the shoring system by a
representative of this office is recommended to verify the conditions or to make recommendations
as are pertinent if different conditions are disclosed during excavation.
7.3 Foundation Design
Based on our subsurface investigation, it is our opinion that the proposed building may be
supported on shallow foundation founded on the competent nature soil at the depth of 9 to 11 feet
below the existing grade. The following presents our preliminary recommendations:
7.3.1 Conventional Foundation (Building)
An allowable bearing value of 3000 pounds per square foot (psf) may be used for design of
continuous or pad footings with a minimum of 18 or 24 inches in width, respectively. All footings
should be a minimum of 24 inches deep and founded on soils encountered at the depths of 9 to
11 feet in the test boring. This value may be increased by one-third when considering short
duration seismic or wind loads.
Resistance to the lateral loads can be assumed to be provided by the passive earth pressure and
the friction between the concrete and competent soils. Passive earth pressure may be computed
as an equivalent fluid pressure of 350 pcf, with a maximum earth pressure of 3000 psf. An
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allowable coefficient of friction between soil and concrete of 0.30 may be used with the dead load
forces. When combining passive pressure and frictional resistance, the passive pressure
component should be reduced by one third (1/3).
7.3.3 Settlement
Settlement of the footings placed as recommended, and subject to no more than allowable loads
is not expected to exceed 3/4 inch. Differential settlement between adjacent columns is not
anticipated to exceed 1/4 inch for the adjacent column spaced at a distance of about 30 feet.
Additionally, the foundation should also be designed to resist the potential seismic induced total
settlement and differential settlement of 0.42 inches and 0.21 inches, respectively.
7.3.4 Lateral Pressures
Active earth pressure from horizontal backfill may be computed as an equivalent fluid weighting of
35 pounds per cubic foot for cantilever retaining wall and 60 pcf for restrained retaining wall. This
value assumes free-draining conditions.
The effect of surcharge, such as traffic loads, adjacent building loads, and etc. within a 1 to 1
projection from the inner edge of the foundation should be included in the design of the retaining
walls. For a uniformly disturbed load behind the wall, a corresponding uniformly distributed lateral
soil pressure equal to 30 percent of the surcharged should be added to the retaining wall design.
Passive earth pressure may be computed as an equivalent fluid pressure of 350 pcf, with a
maximum earth pressure of 3000 psf. An allowable coefficient of friction between soil and
concrete of 0.30 may be used with the dead load forces. When combining passive pressure and
frictional resistance, the passive pressure component should be reduced by one third (1/3).
7.3.5 Wall Seismic Loading
Active earthquake earth pressure distribution on cantilever retaining walls retaining more than 6
feet of soils when the slope of the backfill behind the wall is level may be computed as an
inverted right triangle with 31H psf at the base. Resultant seismic earth force may be applied at
approximately 0.6xH from the top of the footing. H should be measured from top of footing to the
top of wall. The earthquake-induced pressure should be added to the static earth pressure.
Design of walls less than 6 feet in height may neglect the additional seismic pressure.
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7.3.6 Wall Drainage
Any proposed retaining walls at the site should be provided with backdrains to reduce the
potential for the buildup of hydrostatic pressure. Backdrains should consist of 4-inch (minimum)
diameter perforated PVC pipe surrounded by a minimum of 1 cubic foot per lineal foot of clean
coarse gravel wrapped in filter fabric (Mirafi 140 or the equivalent) placed at the base of the wall.
The drain should be covered by no less than 18 inches (vertical) of compacted wall backfill soils.
The backdrain should outlet through non-perforated PVC pipe or weepholes. Alternatively,
commercially available drainage fabric (i.e., J-drain) could be used. The fabric manufacturer’s
recommendations should be followed in the installation of the drainage fabric backdrain.
If there is not enough room for placing the above mentioned drainage systems, an alternative
system such as pre-fabricated drainage system AQUADRAIN 100 BD with a 3-inch drain pipe set in
gravel behind the wall, to prevent the buildup of hydrostatic pressure. This drainpipe may be
connected to a 3-inch drain collector pipe connected to a sump pump.
7.4 Foundation Construction
It is anticipated that the entire structure will be underlain by onsite soils of very low expansion
potential. The following presented our recommendations for the foundation construction.
All footings should be founded at a minimum depth of 24 inches below the lowest adjacent
ground surface. All continuous footings should have at least two No. 5 reinforcing bar placed
both at the top and two No. 5 reinforcing bar placed at the bottom of the footings.
7.5 Concrete Slab
Concrete slab should be founded on properly placed compacted fill or competent natural soils
approved by the project geotechnical consultant. All disturbed soils within the concrete slab areas
should be removed to exposed competent natural soils then backfill with compacted fills to the
design grade. Concrete slabs should be a minimum of 4 inches thick and reinforced with a
minimum of No. 3 reinforcing bar spaced 18-inch each way or its equivalent. All slab
reinforcement should be supported to ensure proper positioning during placement of concrete.
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In order to comply with the requirements of the 2013 CalGreen Section 4.505.2.1 within the
moisture sensitive concrete slab areas, a minimum of 4-inch thick base of ½ inch or larger clean
aggregate should be provided with a vapor barrier in direct contact with concrete. A 10-mil
Polyethylene vapor retarder, with joints lapped not less than 6 inches, should be placed above
the aggregate and in direct contact with the concrete slab. The above foundation and concrete
flatwork reinforcement recommendations are presented in accordance with the geotechnical
engineering viewpoint. Additional reinforcement may be required in the concentrated column
and/or traffic loading areas. Final reinforcement should be designed by the project structural
engineer.
7.6 Temporary Excavation and Backfill
All trench excavations should conform to CAL-OSHA and local safety codes. All utilities trench
backfill should be brought to near optimum moisture content and then compacted to obtain a
minimum relative compaction of 90 percent of ASTM D-1557-12. All temporary excavations
should be observed by a field engineer of this office so as to evaluate the suitability of the
excavation to the exposed soil conditions.
8.0 INSPECTION
As a necessary requisite to the use of this report, the following inspection is recommended:
• Temporary excavations.
• Removal of surficial and unsuitable soils.
• Backfill placement and compaction.
• Utility trench backfill.
The geotechnical engineer should be notified at least 1 day in advance of the start of
construction. A joint meeting between the client, the contractor, and the geotechnical engineer is
recommended prior to the start of construction to discuss specific procedures and scheduling.
9.0 CORROSION POTENTIAL
Chemical laboratory tests were conducted on the existing onsite near surface materials sampled
during QCI’s field investigation to aid in evaluation of soil corrosion potential and the attack on
concrete by sulfate soils. The testing results are presented in Appendix B.
According to 2016 CBC and ACI 318-11, a “negligible” exposure to sulfate can be expected for
concrete placed in contact with the onsite soils. Therefore, Type II cement or its equivalent may
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be used for this project. Based on the resistivity test results, it is estimated that the subsurface
soils are moderately corrosive to buried metal pipe. It is recommended that any underground
steel utilities be blasted and given protective coating. Should additional protective measures be
warranted, a corrosion specialist should be consulted.
10.0 SEISMIC DESIGN
Based on our studies on seismicity, there are no known active faults crossing the property.
However, the subject site is located in southern California, which is a tectonically active area.
Based on 2015 NEHRP Provisions, the following seismic related values may be used:
The Project Structural Engineer should be aware of the information provided above to determine
if any additional structural strengthening is warranted.
11.0 PLAN REVIEW
The 10 scale grading/drainage plan BY CalLand Engineering, Inc. was reviewed. Based on our
review the proposed grading/drainage plan, it is our opinion that the grading and foundation
design and construction recommendations presented in the this report remain valid and
applicable for the planned development.
12.0 COUNTY OF LOS ANGELES 111 STATEMENT
Based on our surface exploration and review of the 10-scale grading plan., it is our opinion that
the proposed structure will be safe against hazard from landslide, settlement, or slippage and the
Seismic Parameters (Latitude: 34.062949, Longitude: -118.08472) Site
Class “D”
Mapped 0.2 Sec Period Spectral Acceleration, Ss 1.941g
Mapped 1.0 Sec Period Spectral Acceleration, S1 0.699g
Site Coefficient for Site Class “D”, Fa 1.2
Site Coefficient for Site Class “D”, Fv 1.7
Maximum Considered Earthquake Spectral Response Acceleration
Parameter at 0.2 Second, SMS 2.329g
Maximum Considered Earthquake Spectral Response Acceleration
Parameter at 1.0 Second, SM1 1.189g
Design Spectral Response Acceleration Parameters for 0.2 sec, SDS 1.552g
Design Spectral Response Acceleration Parameters for 1.0 Sec, SD1 0.792g
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576 E. Lambert Road, Brea, California 92821; Tel: 714-671-1050; Fax: 714-671-1090
proposed construction will have no adverse affect on the geologic stability of the adjacent
properties provided our recommendations presented in this report are followed.
13.0 REMARKS
The conclusions and recommendations contained herein are based on the findings and
observations at the exploratory locations. However, soil materials may vary in characteristics
between locations of the exploratory locations. If conditions are encountered during construction,
which appear to be different from those disclosed by the exploratory work, this office should be
notified so as to recommend the need for modifications.
This report has been prepared in accordance with generally accepted professional engineering
principles and practice. No warranty is expressed or implied. This report is subject to review by
controlling public agencies having jurisdiction.
APPENDIX A
FIELD INVESTIGATION
Subsurface conditions were explored by drilling two 8-inch diameter hollow stem borings to a
maximum depth of 51.5 feet below the existing grade at the subject site at approximate
locations shown on the enclosed Site Plan, Figure 2.
The drilling of the test borings was supervised by a QCI engineer, who continuously logged the
borings and visually classified the soils in accordance with the Unified Soil Classification
System. Ring samples were taken at frequent intervals. These samples were obtained by
driving a sampler with successive blows of 140-pound hammer dropping from a height of 30
inches.
Representative undisturbed samples of the subsurface soils were retained in a series of brass
rings, each having an inside diameter of 2.42 inches and a height of 1.00 inch. All ring samples
were transported to our laboratory. Bulk surface soil samples were also collected for additional
classification and testing.
APPENDIX B
LABORATORY TESTING
During the subsurface exploration, QCI personnel collected relatively undisturbed ring samples
and bulk samples. The following tests were performed on selected soil samples:
Moisture-Density
The moisture content and dry unit weight were determined for each relatively undisturbed soil
sample obtained in the test borings in accordance with ASTM D2937 standard. The results of
these tests are shown on the boring logs in Appendix A.
Shear Tests
Shear tests were performed in a direct shear machine of strain-control type in accordance with
ASTM D3080 standard. The rate of deformation was 0.010 inch per minute. Selected samples
were sheared under varying confining loads in order to determine the Coulomb shear strength
parameters: internal friction angle and cohesion. The shear test results are presented in the
attached plates.
Consolidation Tests
Consolidation tests were performed on selected undisturbed soil samples in accordance with
ASTM D2435 standard. The consolidation apparatus is designed for a one-inch high soil filled
brass ring. Loads are applied in several increments in a geometric progression and the
resulting deformations are recorded at selected time intervals. Porous stones are placed in
contact with the top and bottom of each specimen to permit addition and release of pore fluid.
The samples were inundated with water at a load of two kilo-pounds (kips) per square foot, and
the test results are shown on the attached Figures.
Expansion Index
Laboratory Expansion Index test was conducted on the existing onsite near surface materials
sampled during QCI’s field investigation to aid in evaluation of soil expansion potential. The test
is performed in accordance with ASTM D-4829. The testing result is presented below:
Sample Location
Expansion
Index
Expansion
Potential
B-1 @ 0-3’ 4 Very Low
Corrosion Potential
Chemical laboratory tests were conducted on the existing onsite near surface materials sampled
during QCI’s field investigation to aid in evaluation of soil corrosion potential and the attack on
concrete by sulfate soils. These tests are performed in accordance with California Test Method
417, 422, 532, and 643. The testing results are presented below:
Sample Location
pH
Chloride
(ppm)
Sulfate
(% by weight)
Min. Resistivity
(ohm-cm)
B-1 @ 0’-3’
7.11
102
0.0110
4,300
Percent Passing #200 Sieve
Percent of soil passing #200 sieve was determined for selected soil samples in accordance with
ASTM D1140 standard. The test results are presented in the following table:
Sample Location % Passing #200
B-1 @ 2’ 40.6
B-1 @ 5’ 41.6
B-1 @ 10’ 46.1
B-1 @ 15’ 37.0
B-1 @ 20’ 25.6
B-1 @ 25’ 17.1
B-1 @30’ 27.2
B-1 @ 35’ 24.2
B-1 @ 40’ 28.3
B-1 @ 45’ 58.2
B-1 @ 50’ 60.1
Atterberg Limits
Laboratory Atterberg Limits tests were conducted on the existing onsite materials sampled
during QCI’s field investigation to aid in evaluation of soil liquefaction potential. These tests are
performed in accordance with ASTM D4318. The testing results are presented below:
Sample
Location
USCS
Class.
ASTM
D2488
Liquid Limit
%ASTM
D4318
Plastic
Limit
%ASTM
D4318
Plasticity
Index
%ASTM
D4318
B-1 @ 45’ ML 33 25 8
B-1 @ 50’ ML 33 24 9
Lateral Pressure Calculations
Soil Properties:
Depth 0 - 10 ft. Unit Weight r = 120 pcf,. Cohesion C = 110 psf, Friction Angle φ = 34o
Surcharge at 10 ft. q=120x10=1200, Strength at 10ft. t=110+1200x tan(34)= 919.4 psf.
Equivalent Friction Angle φ’= Arc tan(919.4/1200)=37.45 deg. Use φ=35 degrees
Lateral Pressure (Ref: Geotechnical Engineering Analysis and Evaluation”, Roy Hunt, McGraw
Hill Book Company, 1986)
For Cantilever Retaining Wall
Active Earth Pressure Pa = r x Ka Ka = tan2(45 - φ/2) = 0.271
Pa = 120x 0.271 = 32.5 pcf use 35 pcf
For Restrained Retaining Wall
At Rest Earth Pressure Pa = r x Ko Ko = 1 – sin(φ) = 0.426
Pa = 120 x 0.426 = 51.1 pcf use 60 pcf
Seismic Lateral Pressure
Ref.1: Foundation & Earth Structures, Naval Design Manual, DM 7.02, September 1986
Ref.2: Seismic Earth Pressures on Deep Building Basement, SEAOC 2010 Convention
Proceedings
Ref.3: County of Los Angeles, Department of Public Works, Manual for Preparation of
Geotechnical Reports
Ref 4: City of Los Angeles, “Seismic Lateral Earth Pressures on Basement and Retaining
Walls”, July 16, 2014
PE = 3/8 x r x H2 x kh PGAM = 1.006g
Maximum Ground Acceleration kh = 1.006g x 0.5 x 2/3 = 0.335g
PE = 3/8 x 120 x H2 x 0.335 = 15.1 x H2 use 15.1 x H2 or PE (EFP) = 31H
Passive Earth Pressure (Ref: Geotechnical Engineering Analysis and Evaluation”, Roy Hunt,
McGraw Hill Book Company, 1986)
Earth Pressure Pp = r x Kp Kp = tan2(45 + φ’/2) = 3.69
Pp = 120 x 3.69 = 442.8 pcf > 350 pcf OK
Friction μ = 0.67 x tan(φ) = 0.47 > 0.30 OK
The retaining walls should be designed for the applicable factor of safety against lateral sliding
and overturning in accordance with the current building code.
BEARING CAPACITY EVALUATION
Soil Properties:
Depth 0 – 10 feet, Unit Weight r = 120 pcf
Average Cohesion C = 110 psf
Average Friction Angle φ = 35o
Reference: “Foundation Analysis and Design”, by Joseph E. Bowles, Second Edition, 1977
“Principles of Foundation Engineering”, by Braja M. Das, PWS Publishers, 1984
Equation:
Qult = C x Nc + r x D x Nq + 0.5 x r x B x Nr
C : Cohesion of Soil
R : Unit Weight of Soil
B : Width of Foundation
D : Depth of Foundation
Φ : Friction Angle of Soil
Nc, Nq, Nr = Bearing Capacity Coefficient
Condition:
C : 110 psf
r : 120 pcf
Φ : 35
B : 12 inches
D : 18 inches
Nc = 46.3 Nq = 33.6 Nr = 34.4
Q = 110 x 46.3 + 120 x 1.5 x 33.6 + 0.5 x 120 x 1 x 34.4
= 5093 + 6048 + 2064 psf
=13205 psf
SF = 4
Qall = Q/4 = 3300 psf