HomeMy WebLinkAboutAppendix F1 - Geotechnical Investigationq
GEOTECHNICAL INVESTIGATION
PROPOSED INDUSTRIAL BUILDING
Sierra Avenue, 800± feet North of Casa Grande
Drive
Fontana, California
for
Shea Properties
22885 Savi Ranch Parkway Suite E Yorba Linda California 92887
voice: (714) 685-1115 fax: (714) 685-1118 www.socalgeo.com
May 24, 2020
Shea Properties
130 Vartis Street, Suite 200
Aliso Viejo, California 92656
Attention: Mr. Rick Rutecki
Vice President of Commercial Construction
Project No.: 21G164-1
Subject: Geotechnical Investigation
Proposed Industrial Building
Sierra Avenue, 800± feet North of Casa Grande Drive
Fontana, California
Dear Mr. Rutecki:
In accordance with your request, we have conducted a geotechnical investigation at the subject
site. We are pleased to present this report summarizing the conclusions and recommendations
developed from our investigation.
We sincerely appreciate the opportunity to be of service on this project. We look forward to
providing additional consulting services during the course of the project. If we may be of further
assistance in any manner, please contact our office.
Respectfully Submitted,
SOUTHERN CALIFORNIA GEOTECHNICAL, INC.
Ricardo Frias, RCE 91772
Project Engineer
Robert G. Trazo, GE 2655
Principal Engineer
Distribution: (1) Addressee
Proposed Industrial Building – Fontana, California
Project No. 21G164-1
TABLE OF CONTENTS
1.0 EXECUTIVE SUMMARY 1
2.0 SCOPE OF SERVICES 3
3.0 SITE AND PROJECT DESCRIPTION 4
3.1 Site Conditions 4
3.2 Proposed Development 4
4.0 SUBSURFACE EXPLORATION 5
4.1 Scope of Exploration/Sampling Methods 5
4.2 Geotechnical Conditions 6
5.0 LABORATORY TESTING 7
6.0 CONCLUSIONS AND RECOMMENDATIONS 9
6.1 Seismic Design Considerations 9
6.2 Geotechnical Design Considerations 11
6.3 Site Grading Recommendations 13
6.4 Construction Considerations 17
6.5 Foundation Design and Construction 17
6.6 Floor Slab Design and Construction 19
6.7 Retaining Wall Design and Construction 20
6.8 Pavement Design Parameters 22
7.0 GENERAL COMMENTS 25
APPENDICES
A Plate 1: Site Location Map
Plate 2: Boring and Trench Location Plan
B Boring and Trench Logs
C Laboratory Test Results
D Grading Guide Specifications
E Seismic Design Parameters
Proposed Industrial Building – Fontana, California Project No. 21G164-1
Page 1
1.0 EXECUTIVE SUMMARY
Presented below is a brief summary of the conclusions and recommendations of this
investigation. Since this summary is not all inclusive, it should be read in complete context with
the entire report.
Site Preparation Recommendation
• Initial site preparation should include stripping of any surficial vegetation. This includes the
removal of moderate to dense native grass, weeds, and shrubs present within the site.
These materials should be disposed of off-site.
• The near-surface native alluvial soils within the upper 2 to 3½± feet generally consist of
variable strength silty sands, gravelly sands and sandy gravels with occasional to extensive
cobble and boulder content. The alluvium greater than 2 to 3½± feet generally possess
high strengths and densities and favorable consolidation/collapse characteristics.
• Based on these conditions, remedial grading is recommended within the proposed building
area in order to remove all of the soils disturbed during site stripping and the upper portion
of the near surface soils. The existing soils within the proposed building area should be
overexcavated to a depth of at least 3 feet below existing grade and to a depth of at least 3
feet below proposed pad grade. The proposed foundation influence zones should be
overexcavated to a depth of 3 feet below proposed foundation bearing grade.
• After overexcavation has been completed, the resulting subgrade soils should be evaluated
by the geotechnical engineer to identify any additional soils that should be overexcavated.
The resulting soils should be scarified and thoroughly flooded to achieve a moisture content
of 0 to 4 percent above optimum moisture, to a depth of at least 24 inches. The
overexcavation subgrade soils should then be recompacted under the observation of the
geotechnical engineer. The previously excavated soils may then be replaced as structural
fill, compacted to 90 percent of the ASTM D-1557 maximum dry density.
• Below depths of 2 to 3½± feet, the on-site soils contain significant amounts of oversized
materials, including cobbles and boulders. Where grading will require excavation into these
materials, consideration should be given to using selective grading techniques to remove
the cobbles and/or boulders from these soils prior to reuse as fill.
Foundation Design Recommendations
• Conventional shallow foundations, supported in newly placed compacted fill.
• 3,000 lbs/ft2 maximum allowable soil bearing pressure.
• Reinforcement consisting of at least two (2) No. 5 rebars (1 top and 1 bottom) in strip
footings. Additional reinforcement may be necessary for structural considerations.
Building Floor Slab Design Recommendations
• Conventional Slab-on-Grade, at least 6 inches thick.
• Reinforcement is not required for geotechnical considerations. The actual floor slab
reinforcement to be determined by the structural engineer, based on the proposed loading.
• Modulus of Subgrade Reaction: k = 150 psi/in.
Proposed Industrial Building – Fontana, California Project No. 21G164-1
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Pavement Design Recommendations
ASPHALT PAVEMENTS (R=60)
Materials
Thickness (inches)
Auto Parking and
Auto Drive Lanes
(TI = 4.0 to 5.0)
Truck Traffic
TI = 6.0 TI = 7.0 TI = 8.0 TI = 9.0
Asphalt Concrete 3 3½ 4 5 5½
Aggregate Base 3 3 3 3 4
Compacted Subgrade 12 12 12 12 12
PORTLAND CEMENT CONCRETE PAVEMENTS (R=60)
Materials
Thickness (inches)
Autos and Light
Truck Traffic
(TI = 6.0)
Truck Traffic
TI = 7.0 TI = 8.0 TI = 9.0
PCC 5 5 6½ 8
Compacted Subgrade
(95% minimum compaction) 12 12 12 12
Proposed Industrial Building – Fontana, California Project No. 21G164-1
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2.0 SCOPE OF SERVICES
The scope of services performed for this project was in accordance with our Proposal No.
21P160, dated February 16, 2021. The scope of services included a visual site reconnaissance,
subsurface exploration, field and laboratory testing, and geotechnical engineering analysis to
provide criteria for preparing the design of the building foundations, building floor slab, and
parking lot pavements along with site preparation recommendations and construction
considerations for the proposed development. The evaluation of the environmental aspects of
this site was beyond the scope of services for this geotechnical investigation.
Proposed Industrial Building – Fontana, California Project No. 21G164-1
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3.0 SITE AND PROJECT DESCRIPTION
3.1 Site Conditions
The subject site is located on the east side of Sierra Avenue, approximately 800 feet north of
Casa Grande Drive in Fontana, California. The site is bounded to the north, west, and east by
vacant land, and to the west by Sierra Avenue. The general location of the site is illustrated on
the Site Location Map, included as Plate 1 in Appendix A of this report.
The site consists of a rectangular-shaped lot, 11.03± acres in size. The site is currently vacant
and undeveloped with the exception of a wood-framed single-family residence (SFR) located in
the southwest corner of the site approximately 2,000 ft2 in size. The SFR is assumed to be
supported on conventional shallow foundations with a concrete slab-on-grade floor. The ground
surface surrounding the SFR consists of an open-graded gravel or aggregate base drive lane.
The remaining areas surrounding the SFR as well as the reminder of the site consists of
hummocky soil covered by moderate to dense native grass and shrub growth throughout. Some
cobbles and boulders are present at the ground surface throughout the site.
Detailed topographic information was not available at the time of this report. Based on visual
observations made at the time of the subsurface investigation and from elevations obtained
from Google Earth, the overall site topography generally slopes downward to the south and
southeast at a gradient of less than 2± percent. The site ranges from 1779± feet msl to 1762±
feet msl in the northwest and southeast corners, respectively.
3.2 Proposed Development
SCG was provided with conceptual site plan prepared by Thienes Engineering, Inc., the project
civil engineer. Based on this plan, the site will be developed with one industrial building, with a
footprint of 203,000± ft² in size. The new building will be located in the central area of the site.
Dock-high doors will be constructed along a portion of the south building wall. The building will
be surrounded by asphaltic concrete pavements in the parking and drive areas, Portland cement
concrete pavements in the truck court areas, and limited areas of concrete flatwork and
landscape planters throughout.
Detailed structural information has not been provided. It is assume that the new building will be
a single-story structure of tilt-up concrete construction, typically supported on a conventional
shallow foundation system with a concrete slab-on-grade floor. Based on the assumed
construction, maximum column and wall loads are expected to be on the order of 100 kips and
4 to 7 kips per linear foot, respectively.
No significant amounts of below grade construction, such as basements or crawl spaces, are
expected to be included in the proposed development. Based on the assumed topography, cuts
and fills of 2 to 3± feet are expected to be necessary to achieve the proposed site grades.
Proposed Industrial Building – Fontana, California Project No. 21G164-1
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4.0 SUBSURFACE EXPLORATION
4.1 Scope of Exploration/Sampling Methods
The subsurface exploration conducted for this project consisted of four (4) borings advanced to
depths of 15 to 20± feet below existing site grades. In addition to the four borings, a total of
four (4) trenches were excavated at the site to depths of 5 to 9½± feet below existing site
grades. Boring No. B-1 was terminated at a depth shallower than planned due to refusal on
extensive cobbles. Trench No T-3 was terminated at a depth shallower than planned due to
severe caving. All of the borings and trenches were logged during drilling and excavation by a
member of our staff.
The borings were advanced with hollow-stem augers, by a conventional truck-mounted drilling
rig. The trenches were excavated using a rubber tire backhoe with a 36-inch-wide bucket.
Representative bulk and in-situ soil samples were taken during drilling and excavation.
Relatively undisturbed in-situ samples were taken with a split barrel “California Sampler”
containing a series of one inch long, 2.416± inch diameter brass rings. This sampling method is
described in ASTM Test Method D-3550. In-situ samples were also taken using a 1.4± inch
inside diameter split spoon sampler, in general accordance with ASTM D-1586. Both of these
samplers were driven into the ground with successive blows of a 140-pound weight falling 30
inches. The blow counts obtained during driving are recorded for further analysis. Bulk samples
were collected in plastic bags to retain their original moisture content. The relatively
undisturbed ring samples were placed in molded plastic sleeves that were then sealed and
transported to our laboratory.
Several of the borings were offset due to the presence of cobbles and/or boulders. Cobbles
were observed in the auger spoils at various depths at all of the boring locations. It is not
possible to determine the quantity and extent of the cobbles and boulders using conventional
hollow-stem augers and conventional split-spoon samplers, since the diameters of the samplers
are relatively small compared to cobble and boulder-sized particles. Therefore, the cobble and
boulder content is expected to vary from the estimates shown on the Boring Logs. However,
cobbles and boulders were observed during excavation and logging at all of the exploratory
trenches. Based on our observations at the four exploratory trenches, and difficult drilling
conditions encountered at the boring locations, the subsurface profile possesses varying
quantities of cobble and boulder content throughout, with zones of extensive cobbles and
boulders.
The approximate locations of the borings and trenches are indicated on the Boring and Trench
Location Plan, included as Plate 2 in Appendix A of this report. The Boring and Trench Logs,
which illustrate the conditions encountered at the boring and trench locations, as well as the
results of some of the laboratory testing, are included in Appendix B.
Proposed Industrial Building – Fontana, California Project No. 21G164-1
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4.2 Geotechnical Conditions
Alluvium
Native alluvial soils were encountered at the ground surface at all of the boring and trench
locations. The near-surface alluvial soils within the upper 2 to 3½± feet at some of the borings
consist of medium dense to dense silty sands with varying gravel content. At greater depths the
alluvium generally consists of dense to very dense gravelly sands, sandy gravels, and gravels
with occasional to extensive cobbles and boulders, extending to the maximum depth explored
of 20± feet.
Groundwater
Free water was not encountered during the drilling of any of the borings or during excavation of
any of the trenches. Based on the lack of any water within the borings and trenches, and the
moisture contents of the recovered soil samples, the static groundwater is considered to have
existed at a depth in excess of 20± feet at the time of the subsurface exploration.
As part of our research, we reviewed available groundwater data in order to determine the
historic high groundwater level for the site. The primary reference used to determine the
groundwater depths in this area is the California Department of Water Resources website,
http://www.water.ca.gov/waterdatalibrary/. The nearest monitoring well is located
approximately ½ mile northwest from the site. Water level readings within this monitoring well
indicates high groundwater levels of 159± feet below the ground surface in January 1992.
Proposed Industrial Building – Fontana, California Project No. 21G164-1
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5.0 LABORATORY TESTING
The soil samples recovered from the subsurface exploration were returned to our laboratory for
further testing to determine selected physical and engineering properties of the soils. The tests
are briefly discussed below. It should be noted that the test results are specific to the actual
samples tested, and variations could be expected at other locations and depths.
Classification
All recovered soil samples were classified using the Unified Soil Classification System (USCS), in
accordance with ASTM D-2488. The field identifications were then supplemented with additional
visual classifications and/or by laboratory testing. The USCS classifications are shown on the
Boring and Trench Logs and are periodically referenced throughout this report.
In-situ Density and Moisture Content
The density has been determined for selected relatively undisturbed ring samples. These
densities were determined in general accordance with the method presented in ASTM D-2937.
The results are recorded as dry unit weight in pounds per cubic foot. The moisture contents are
determined in accordance with ASTM D-2216, and are expressed as a percentage of the dry
weight. These test results are presented on the Boring and Trench Logs.
Consolidation
Selected soil samples were tested to determine their consolidation potential, in accordance with
ASTM D-2435. The testing apparatus is designed to accept either natural or remolded samples
in a one-inch high ring, approximately 2.416 inches in diameter. Each sample is then loaded
incrementally in a geometric progression and the resulting deflection is recorded at selected
time intervals. Porous stones are in contact with the top and bottom of the sample to permit
the addition or release of pore water. The samples are typically inundated with water at an
intermediate load to determine their potential for collapse or heave. The results of the
consolidation testing are plotted on Plates C-1 through C-4 in Appendix C of this report.
Maximum Dry Density and Optimum Moisture Content
A representative bulk sample has been tested for its maximum dry density and optimum
moisture content. The results have been obtained using the Modified Proctor procedure, per
ASTM D-1557, and are presented on Plate C-5 in Appendix C of this report. This test is
generally used to compare the in-situ densities of undisturbed field samples, and for later
compaction testing. Additional testing of other soil types or soil mixes may be necessary at a
later date.
Proposed Industrial Building – Fontana, California Project No. 21G164-1
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Soluble Sulfates
Representative samples of the near-surface soils were submitted to a subcontracted analytical
laboratory for determination of soluble sulfate content. Soluble sulfates are naturally present in
soils, and if the concentration is high enough, can result in degradation of concrete which
comes into contact with these soils. The results of the soluble sulfate testing are presented
below, and are discussed further in a subsequent section of this report.
Sample Identification Soluble Sulfates (%) ACI Classification
B-3 @ 0 to 5 feet 0.002 Not Applicable (S0)
Corrosivity Testing
One representative sample of the near-surface soils was submitted to a subcontracted corrosion
engineering laboratory to identify potentially corrosive characteristics with respect to common
construction materials. The corrosivity testing included a determination of the electrical
resistivity, pH, and chloride and nitrate concentrations of the soils, as well as other tests. The
results of some of these tests are presented below.
Sample Identification
Saturated
Resistivity
(ohm-cm)
pH Chlorides
(mg/kg)
Nitrates
(mg/kg)
B-3 @ 0 to 5 feet 60,000 6.0 5.8 3.6
Proposed Industrial Building – Fontana, California Project No. 21G164-1
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6.0 CONCLUSIONS AND RECOMMENDATIONS
Based on the results of our review, field exploration, laboratory testing and geotechnical
analysis, the proposed development is considered feasible from a geotechnical standpoint. The
recommendations contained in this report should be taken into the design, construction, and
grading considerations.
The recommendations are contingent upon all grading and foundation construction activities
being monitored by the geotechnical engineer of record. The recommendations are provided
with the assumption that an adequate program of client consultation, construction monitoring,
and testing will be performed during the final design and construction phases to verify
compliance with these recommendations. Maintaining Southern California Geotechnical, Inc.,
(SCG) as the geotechnical consultant from the beginning to the end of the project will provide
continuity of services. The geotechnical engineering firm providing testing and observation
services shall assume the responsibility of Geotechnical Engineer of Record.
The Grading Guide Specifications, included as Appendix D, should be considered part of this
report, and should be incorporated into the project specifications. The contractor and/or owner
of the development should bring to the attention of the geotechnical engineer any conditions
that differ from those stated in this report, or which may be detrimental for the development.
6.1 Seismic Design Considerations
The subject site is located in an area which is subject to strong ground motions due to
earthquakes. The performance of a site specific seismic hazards analysis was beyond the scope
of this investigation. However, numerous faults capable of producing significant ground motions
are located near the subject site. Due to economic considerations, it is not generally considered
reasonable to design a structure that is not susceptible to earthquake damage. Therefore,
significant damage to structures may be unavoidable during large earthquakes. The proposed
structures should, however, be designed to resist structural collapse and thereby provide
reasonable protection from serious injury, catastrophic property damage and loss of life.
Faulting and Seismicity
Research of available maps indicates that the subject site is not located within an Alquist-Priolo
Earthquake Fault Zone. Furthermore, SCG did not identify any evidence of faulting during the
geotechnical investigation. Therefore, the possibility of significant fault rupture on the site is
considered to be low.
Seismic Design Parameters
The 2019 California Building Code (CBC) provides procedures for earthquake resistant structural
design that include considerations for on-site soil conditions, occupancy, and the configuration
of the structure including the structural system and height. The seismic design parameters
Proposed Industrial Building – Fontana, California Project No. 21G164-1
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presented below are based on the soil profile and the proximity of known faults with respect to
the subject site.
Based on standards in place at the time of this report, the proposed development is expected to
be designed in accordance with the requirements of the 2019 edition of the California Building
Code (CBC), which was adopted on January 1, 2020.
The 2019 CBC Seismic Design Parameters have been generated using the SEAOC/OSHPD
Seismic Design Maps Tool, a web-based software application available at the website
www.seismicmaps.org. This software application calculates seismic design parameters in
accordance with several building code reference documents, including ASCE 7-16, upon which
the 2019 CBC is based. The application utilizes a database of risk-targeted maximum considered
earthquake (MCER) site accelerations at 0.01-degree intervals for each of the code documents.
The tables below were created using data obtained from the application. The output generated
from this program is included as Plate E-1 in Appendix E of this report.
2019 CBC SEISMIC DESIGN PARAMETERS
Parameter Value
Mapped Spectral Acceleration at 0.2 sec Period SS 2.171
Mapped Spectral Acceleration at 1.0 sec Period S1 0.735
Site Class --- C
Site Modified Spectral Acceleration at 0.2 sec Period SMS 2.605
Site Modified Spectral Acceleration at 1.0 sec Period SM1 1.029
Design Spectral Acceleration at 0.2 sec Period SDS 1.737
Design Spectral Acceleration at 1.0 sec Period SD1 0.686
Based on the presence of dense to very dense soils, generally encountered in a majority of the
boring and trench locations, we have classified this site as Site Class C in accordance with ASCE
7-16, Chapter 20. Additionally, ASCE 7-16 allows for the determination of site-specific seismic
design parameters in accordance with ASCE 7-16 Chapter 21 instead of using the code derived
values presented above. Depending upon structural considerations, and the site classification of
Site Class C, it may be desirable to perform a ground motion hazard analysis for this site in
accordance with ASCE 7-16 Section 21.2. At the client’s request, SCG can prepare a proposal to
perform a ground motion hazard analysis.
Liquefaction
Liquefaction is the loss of strength in generally cohesionless, saturated soils when the pore-
water pressure induced in the soil by a seismic event becomes equal to or exceeds the
overburden pressure. The primary factors which influence the potential for liquefaction include
groundwater table elevation, soil type and grain size characteristics, relative density of the soil,
initial confining pressure, and intensity and duration of ground shaking. The depth within which
the occurrence of liquefaction may impact surface improvements is generally identified as the
upper 50 feet below the existing ground surface. Liquefaction potential is greater in saturated,
Proposed Industrial Building – Fontana, California Project No. 21G164-1
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loose, poorly graded fine sands with a mean (d50) grain size in the range of 0.075 to 0.2 mm
(Seed and Idriss, 1971). Clayey (cohesive) soils or soils which possess clay particles
(d<0.005mm) in excess of 20 percent (Seed and Idriss, 1982) are generally not considered to
be susceptible to liquefaction, nor are those soils which are above the historic static
groundwater table.
The California Geological Survey (CGS) has not yet conducted seismic hazard mapping in the
area of the subject site. The San Bernardino County Land Use Plan, Geologic Hazard Overlays,
Devore Quadrangle, FH21C, indicates that the subject site is not located within a zone of
liquefaction susceptibility. In addition, the subsurface conditions at the boring and trench
locations are not considered to be conducive to liquefaction. These conditions generally consist
of medium dense to very dense, well graded, granular soils, and no evidence of a static water
table within the upper 20± feet. Based on the mapping performed by San Bernardino County
and the conditions encountered at the boring and trench locations, liquefaction is not
considered to be a design concern for this project.
6.2 Geotechnical Design Considerations
General
The near-surface native alluvial soils within the upper 2 to 3½± feet possess loose strengths. In
their present condition, these materials are not considered suitable to support the foundation
loads of the new building. The native alluvial soils at greater depths generally consist of high
strength fine to coarse sands, gravelly sands and sandy gravels. Laboratory testing indicates
that the soils encountered at a depth of 3½± feet and greater possess favorable
consolidation/collapse characteristics.
Based on these conditions, remedial grading is considered warranted within the proposed
building area in order to remove all of the upper portion of the near-surface native alluvial soils.
Settlement
The proposed remedial grading will remove the potentially collapsible/variable density alluvium
from within the proposed building area. The native soils that will remain in place below the
recommended depth of overexcavation will not be subject to significant stress increases from
the foundations of the new structure. Therefore, following completion of the recommended
grading, post-construction settlements are expected to be within tolerable limits.
Expansion
The on-site soils generally consist of silty sands and fine to coarse sands with varying amounts
of gravel, cobbles and boulders. These materials have been visually classified as non-expansive.
Therefore, no design considerations related to expansive soils are considered warranted for this
site.
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Soluble Sulfates
The results of the soluble sulfate testing indicated a sulfate concentration of approximately
0.002 percent for the selected sample of the near-surface soils. This concentration is considered
to be “not applicable” (S0) with respect to the American Concrete Institute (ACI) Publication
318-14 Building Code Requirements for Structural Concrete and Commentary, Section 4.3.
Therefore, specialized concrete mix designs are not considered to be necessary, with regard to
sulfate protection purposes. It is, however, recommended that additional soluble sulfate testing
be conducted at the completion of rough grading to verify the soluble sulfate concentrations of
the soils which are present at pad grade within the building area.
Corrosion Potential
The results of laboratory testing indicate that the on-site soils possess a saturated resistivity of
60,000 ohm-cm, and a pH value of 6.0. These test results have been evaluated in accordance
with guidelines published by the Ductile Iron Pipe Research Association (DIPRA). The DIPRA
guidelines consist of a point system by which characteristics of the soils are used to quantify the
corrosivity characteristics of the site. Sulfides, and redox potential are factors that are also used
in the evaluation procedure. We have evaluated the corrosivity characteristics of the on-site
soils using resistivity, pH, and moisture content. Based on these factors, and utilizing the DIPRA
procedure, the on-site soils are not considered to be corrosive to ductile iron pipe. Therefore,
polyethylene encasement or some other appropriate method of protection will not be required
for iron pipes.
A relatively low concentration (5.8 mg/kg) of chlorides were detected in the sample submitted
for corrosivity testing. In general, soils possessing chloride concentrations in excess of 500 parts
per million (ppm) are considered to be corrosive with respect to steel reinforcement within
reinforced concrete. Based on the lack of any significant chlorides in the tested sample, the site
is considered to have a C1 chloride exposure in accordance with the American Concrete
Institute (ACI) Publication 318 Building Code Requirements for Structural Concrete and
Commentary. Therefore, a specialized concrete mix design for reinforced concrete for protection
against chloride exposure is not considered warranted.
Nitrates present in soil can be corrosive to copper tubing at concentrations greater than 50
mg/kg. The tested sample possess a nitrate concentrations of 3.6 mg/kg. Based on this test
result, the on-site soils are not considered to be corrosive to copper pipe.
Since SCG does not practice in the area of corrosion engineering, we recommend that the client
contact a corrosion engineer to provide a more thorough evaluation.
Shrinkage/Subsidence
Due to the gravel and cobble content of the on-site soils, determining accurate shrinkage values
is very difficult and may not be feasible using conventional drilling and sampling methods.
However, based on the results of the subsurface exploration and laboratory testing, removal
and recompaction of the near surface native alluvium is estimated to result in an average
shrinkage of 7 to 22± percent. Shrinkage estimates for the individual samples range between 2
and 28 percent based on the results of density testing and the assumption that the on-site soils
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will be compacted to about 92 percent of the ASTM D-1557 maximum dry density. This
estimate does not account for any volume loss due to the removal of oversized materials, if
necessary. If a more accurate shrinkage estimate is desired, SCG can perform a more detailed
shrinkage study. In-place densities would be determined using in-situ methods instead of
laboratory density testing on small-diameter samples such as those obtained using split-spoon
samplers at the boring locations.
Minor ground subsidence is expected to occur in the soils below the zone of removal, due to
settlement and machinery working. The subsidence is estimated to be 0.1 to 0.15± feet. This
estimate may be used for grading in areas that are underlain by native alluvial soils.
These estimates are based on previous experience and the subsurface conditions encountered
at the boring locations. The actual amount of subsidence is expected to be variable and will be
dependent on the type of machinery used, repetitions of use, and dynamic effects, all of which
are difficult to assess precisely.
Grading and Foundation Plan Review
Grading and foundation plans were not available at the time of this report. It is therefore
recommended that we be provided with copies of the preliminary grading and foundation plans,
when they become available, for review with regard to the conclusions, recommendations, and
assumptions contained within this report.
6.3 Site Grading Recommendations
The grading recommendations presented below are based on the subsurface conditions
encountered at the boring and trench locations and our understanding of the proposed
development. We recommend that all grading activities be completed in accordance with the
Grading Guide Specifications included as Appendix D of this report, unless superseded by site-
specific recommendations presented below.
Site Stripping
Initial site preparation should include stripping of any surficial vegetation. This includes the
removal of the moderate to dense native grass, weeds, and shrubs present within the site.
These materials should be disposed of off-site. Root balls associated with the shrubs should be
removed in their entirety, and the resultant excavations should be backfilled with compacted
structural fill soils. The actual extent of site stripping should be determined in the field by the
geotechnical engineer, based on the organic content and stability of the materials encountered.
Treatment of Existing Soils: Building Pad
Overexcavation should be performed within the proposed building area to remove all of the
upper portion of the near-surface native alluvium. Based on conditions encountered at the
boring and trench locations, these loose alluvial soils extend to depths of 2½ to 3½± feet. The
building pad overexcavation should also extend to a depth of at least 3 feet below existing
grade and to a depth of at least 3 feet below proposed pad grade throughout the building area.
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Where not encompassed within the general building pad overexcavations, additional
overexcavation should be performed within the influence zones of the new foundations, to
provide for a new layer of compacted structural fill extending to a depth of 3 feet below
proposed foundation bearing grade.
The overexcavation areas should extend at least 5 feet beyond the building and foundation
perimeters, and to an extent equal to the depth of fill below the new foundations. If the
proposed structure incorporates any exterior columns (such as for a canopy or overhang) the
overexcavations should also encompass these areas.
Following completion of the overexcavation, the subgrade soils within the building area should
be evaluated by the geotechnical engineer to verify their suitability to serve as the structural fill
subgrade, as well as to support the foundation loads of the new structure. This evaluation
should include proofrolling with a heavy rubber-tire vehicle to identify any soft, loose or
otherwise unstable soils that must be removed. Some localized areas of deeper excavation may
be required if dry, loose, porous, or low density native soils are encountered at the base of the
overexcavation.
After a suitable overexcavation subgrade has been achieved, the exposed soils
should be scarified to a depth of at least 12 inches, and thoroughly flooded to raise
the moisture content of the underlying soils to at least 0 to 4 percent above
optimum moisture content, extending to a depth of at least 24 inches. The moisture
conditioning of the overexcavation subgrade soils should be verified by the geotechnical
engineer. The subgrade soils should then be recompacted to at least 90 percent of the ASTM D-
1557 maximum dry density. The previously excavated soils may then be replaced as compacted
structural fill.
Treatment of Existing Soils: Retaining Walls and Site Walls
The existing soils within the areas of any proposed retaining walls and site walls should be
overexcavated to a depth of 2 feet below foundation bearing grade and replaced as compacted
structural fill as discussed above for the proposed building pad. Any dry, loose, alluvial soils
within any of these foundation areas should be removed in their entirety. Please note that any
erection pads used to construct the walls are considered to be part of the foundation system.
The overexcavation subgrade soils should be evaluated by the geotechnical engineer prior to
scarifying, moisture conditioning, and recompacting the upper 12 inches of exposed subgrade
soils, as discussed for the building areas. The previously excavated soils may then be replaced
as compacted structural fill.
If the full lateral extent of overexcavation is not achievable for the proposed walls, the
foundations should be redesigned using a lower bearing pressure. The geotechnical engineer of
record should be contacted for recommendations pertaining to this type of condition.
Proposed Industrial Building – Fontana, California Project No. 21G164-1
Page 15
Treatment of Existing Soils: Parking Areas
Based on economic considerations, removal and replacement of the existing potentially
collapsible alluvial soils is not considered warranted within the proposed parking areas.
Subgrade preparation in the new parking and drive areas should initially consist of removal of
all soils disturbed during stripping operations.
The geotechnical engineer should then evaluate the subgrade to identify any areas of additional
unsuitable soils. The subgrade soils should then be scarified to a depth of 12± inches, moisture
conditioned to 0 to 4 percent above optimum moisture content (to a depth of at least 24
inches) and recompacted to at least 90 percent of the ASTM D-1557 maximum dry density.
Based on the presence of variable strength surficial soils throughout the site, it is expected that
some isolated areas of additional overexcavation may be required to remove zones of lower
strength, unsuitable soils.
The grading recommendations presented above for the proposed parking and drive areas
assume that the owner and/or developer can tolerate minor amounts of settlement within the
proposed parking areas. The grading recommendations presented above do not completely
mitigate the extent of collapsible native soils or undocumented fill soils in the parking areas. As
such, settlement and associated pavement distress could occur. Typically, repair of such
distressed areas involves significantly lower costs than completely mitigating these soils at the
time of construction. If the owner cannot tolerate the risk of such settlements, the flatwork,
parking and drive areas should be overexcavated to a depth of 2 feet below proposed
pavement subgrade elevation, with the resulting soils replaced as compacted structural fill.
Treatment of Existing Soils: Flatwork Areas
Subgrade preparation in the new flatwork areas should initially consist of removal of all soils
disturbed during stripping and demolition operations. The geotechnical engineer should then
evaluate the subgrade to identify any areas of additional unsuitable soils. The subgrade soils
should then be scarified to a depth of 12 inches, moisture conditioned to 0 to 4 percent above
optimum, and recompacted to at least 90 percent of the ASTM D-1557 maximum dry density.
Based on the presence of variable strength soils throughout the site, it is expected that some
isolated areas of additional overexcavation may be required to remove zones of lower strength,
unsuitable soils.
Fill Placement
• Fill soils should be placed in thin (6 inches), near-horizontal lifts, moisture conditioned
to 0 to 4 percent above the optimum moisture content, and compacted.
• On-site soils may be used for fill provided they are cleaned of any debris to the
satisfaction of the geotechnical engineer. The on-site soils, especially below depths
of 2 to 3½± feet, possess significant quantities of oversized material,
including cobbles and occasional boulders. Some sorting and/or crushing of
these materials may be required to generate soils that are suitable for reuse
as compacted structural fill.
• All grading and fill placement activities should be completed in accordance with the
requirements of the CBC and the grading code of the city of Fontana.
Proposed Industrial Building – Fontana, California Project No. 21G164-1
Page 16
• All fill soils should be compacted to at least 90 percent of the ASTM D-1557 maximum
dry density. Fill soils should be well mixed.
• Compaction tests should be performed periodically by the geotechnical engineer as
random verification of compaction and moisture content. These tests are intended to aid
the contractor. Since the tests are taken at discrete locations and depths, they may not
be indicative of the entire fill and therefore should not relieve the contractor of his
responsibility to meet the job specifications.
Selective Grading and Oversized Material Placement
The existing soils beginning from the ground surface possess significant cobble and/or boulder
content. Based on conditions encountered at the boring and trench locations, the soils at depths
of 2 to 3½± feet and greater possess appreciable cobbles and/or boulders. It is expected that
large scrapers (Caterpillar 657 or equivalent) will be adequate to move the cobble containing
soils as well as some of the soils containing smaller boulders. However, some larger boulders
(2± feet in size) were also encountered at the boring and trench locations. It will likely be
necessary to move such larger boulders individually, and place them as oversized materials in
accordance with the Grading Guide Specifications, in Appendix D of this report.
Since the proposed grading will require excavation of cobble and boulder containing soils, it
may be desirable to selectively grade the proposed building pad area. The presence of particles
greater than 3 inches in diameter within the upper 1 to 3 feet of the building pad subgrade will
impact the utility and foundation excavations. Depending on the depths of fills required within
the proposed parking areas, it may be feasible to sort the on-site soils, placing the materials
greater than 3 inches in diameter within the lower depths of the fills, and limiting the upper 1 to
3 feet of soils to materials less than 3 inches in size. Oversized materials could also be placed
within the lower depths of the recommended overexcavations. In order to achieve this grading,
it would likely be necessary to use rock buckets and/or rock sieves to separate the oversized
materials from the remaining soil. Although such selective grading will facilitate further
construction activities, it is not considered mandatory and a suitable subgrade could be
achieved without such extensive sorting. However, in any case it is recommended that all
materials greater than 6 inches in size be excluded from the upper 1 foot of the surface of any
compacted fills. The placement of any oversized materials should be performed in
accordance with the grading guide specifications included in Appendix D of this
report. If disposal of oversized materials is required, rock blankets or windrows should be used
and such areas should be observed during construction and placement by a representative of
the geotechnical engineer.
Imported Structural Fill
All imported structural fill should consist of very low expansive (EI < 20), well graded soils
possessing at least 10 percent fines (that portion of the sample passing the No. 200 sieve). As
discussed previously, imported fill for use below new flatwork should consist of very low
expansive (EI < 20) material. Additional specifications for structural fill are presented in the
Grading Guide Specifications, included as Appendix D.
Proposed Industrial Building – Fontana, California Project No. 21G164-1
Page 17
Utility Trench Backfill
In general, all utility trench backfill soils should be compacted to at least 90 percent of the
ASTM D-1557 maximum dry density. It is recommended that materials in excess of 3 inches in
size not be used for utility trench backfill. Compacted trench backfill should conform to the
requirements of the local grading code, and more restrictive requirements may be indicated by
the city of Fontana. All utility trench backfills should be witnessed by the geotechnical engineer.
The trench backfill soils should be compaction tested where possible; probed and visually
evaluated elsewhere.
Utility trenches which parallel a footing, and extending below a 1h:1v plane projected from the
outside edge of the footing should be backfilled with structural fill soils, compacted to at least
90 percent of the ASTM D-1557 standard. Pea gravel backfill should not be used for these
trenches.
6.4 Construction Considerations
Excavation Considerations
The near surface soils generally consist of silty sands and fine to coarse sands with varying
gravel, cobble, and boulder content. Based on their composition, minor to moderate caving of
shallow excavations may occur. Where caving occurs within shallow excavations, flattened
excavation slopes may be sufficient to provide excavation stability. On a preliminary basis,
temporary excavations should be laid back at a slope no steeper than 2h:1v. Deeper
excavations may require some form of external stabilization such as shoring or bracing.
Maintaining adequate moisture content within the near surface soils will improve excavation
stability. All excavation activities on this site should be conducted in accordance with Cal-OSHA
regulations.
Groundwater
The static groundwater table at this site is considered to exist at a depth in excess of 20 feet.
Therefore, groundwater is not expected to impact the grading or foundation construction
activities.
6.5 Foundation Design and Construction
Based on the preceding grading recommendations, it is assumed that the new building pad will
be underlain by structural fill soils used to replace the upper portion of the native soils. The new
structural fill soils are expected to extend to a depth of at least 3 feet below foundation bearing
grade underlain by existing native soils that have been densified in place. Based on this
subsurface profile, the proposed structure may be supported on shallow foundations.
Foundation Design Parameters
New square and rectangular footings may be designed as follows:
Proposed Industrial Building – Fontana, California Project No. 21G164-1
Page 18
• Maximum, net allowable soil bearing pressure: 3,000 lbs/ft2.
• Minimum wall/column footing width: 14 inches/24 inches.
• Minimum longitudinal steel reinforcement within strip footings: Two (2) No. 5 rebars (1
top and 1 bottom).
• Minimum foundation embedment: 12 inches into suitable structural fill soils, and at least
18 inches below adjacent exterior grade. Interior column footings may be placed
immediately beneath the floor slab.
• It is recommended that the perimeter building foundations be continuous across all
exterior doorways. Any flatwork adjacent to the exterior doors should be doweled into
the perimeter foundations in a manner determined by the structural engineer.
The allowable bearing pressures presented above may be increased by 1/3 when considering
short duration wind or seismic loads. The minimum steel reinforcement recommended above is
based on standard geotechnical practice. The actual design of the foundations should be
determined by the structural engineer.
Foundation Construction
The foundation subgrade soils should be evaluated at the time of overexcavation, as discussed
in Section 6.3 of this report. It is further recommended that the foundation subgrade soils be
evaluated by the geotechnical engineer immediately prior to steel or concrete placement. Soils
suitable for direct foundation support should consist of newly placed structural fill, compacted to
at least 90 percent of the ASTM D-1557 maximum dry density. Any unsuitable materials should
be removed to a depth of suitable bearing compacted structural fill, with the resulting
excavations backfilled with compacted fill soils. As an alternative, lean concrete slurry (500 to
1,500 psi) may be used to backfill such isolated overexcavations.
The foundation subgrade soils should also be properly moisture conditioned to 0 to 4 percent
above the Modified Proctor optimum, to a depth of at least 12 inches below bearing grade.
Since it is typically not feasible to increase the moisture content of the floor slab
and foundation subgrade soils once rough grading has been completed, care should
be taken to maintain the moisture content of the building pad subgrade soils
throughout the construction process.
Estimated Foundation Settlements
Post-construction total and differential settlements of shallow foundations designed and
constructed in accordance with the previously presented recommendations are estimated to be
less than 1.0 and 0.5 inches, respectively, under static conditions. Differential movements are
expected to occur over a 50-foot span, thereby resulting in an angular distortion of less than
0.002 inches per inch.
Proposed Industrial Building – Fontana, California Project No. 21G164-1
Page 19
Lateral Load Resistance
Lateral load resistance will be developed by a combination of friction acting at the base of
foundations and slabs and the passive earth pressure developed by footings below grade. The
following friction and passive pressure may be used to resist lateral forces:
• Passive Earth Pressure: 300 lbs/ft3
• Friction Coefficient: 0.30
These are allowable values, and include a factor of safety. When combining friction and passive
resistance, the passive pressure component should be reduced by one-third. These values
assume that footings will be poured directly against compacted structural fill. The maximum
allowable passive pressure is 3,000 lbs/ft2.
6.6 Floor Slab Design and Construction
Subgrades which will support new floor slab should be prepared in accordance with the
recommendations contained in the Site Grading Recommendations section of this report.
Based on the anticipated grading which will occur at this site, the floor of the proposed
structure may be constructed as a conventional slab-on-grade supported on newly placed
structural fill, extending to a depth of at least 3 feet below finished pad grade. Based on
geotechnical considerations, the floor-slab may be designed as follows:
• Minimum slab thickness: 6 inches.
• Modulus of Subgrade Reaction: k = 150 psi/in.
• Minimum slab reinforcement: Not required for geotechnical considerations. The actual
floor slab reinforcement should be determined by the structural engineer, based on the
imposed loading.
• Slab underlayment: If moisture sensitive floor coverings will be used then minimum slab
underlayment should consist of a moisture vapor barrier constructed below the entire
area of the proposed slab where such moisture floor coverings will be used. The
moisture vapor barrier should meet or exceed the Class A rating as defined by ASTM E
1745-97 and have a permeance rating less than 0.01 perms as described in ASTM E 96-
95 and ASTM E 154-88. A polyolefin material such as a 15 mil. Stego® Wrap Vapor
Barrier or equivalent will meet these specifications. The moisture vapor barrier should be
properly constructed in accordance with all applicable manufacturer specifications. Given
that a rock free subgrade is anticipated and that a capillary break is not required, sand
below the barrier is not required. The need for sand and/or the amount of sand above
the moisture vapor barrier should be specified by the structural engineer or concrete
contractor. The selection of sand above the barrier is not a geotechnical engineering
issue and hence outside our purview. Where moisture sensitive floor coverings are not
anticipated, the vapor barrier may be eliminated.
Proposed Industrial Building – Fontana, California Project No. 21G164-1
Page 20
• Moisture condition the floor slab subgrade soils to 0 to 4 percent above the Modified
Proctor optimum moisture content, to a depth of 12 inches. The moisture content of the
floor slab subgrade soils should be verified by the geotechnical engineer within 24 hours
prior to concrete placement.
• Proper concrete curing techniques should be utilized to reduce the potential for slab
curling or the formation of excessive shrinkage cracks.
The actual design of the floor slab should be completed by the structural engineer to verify
adequate thickness and reinforcement.
6.7 Retaining Wall Design and Construction
Although not indicated on the site plan, some small (less than 6 feet in height) retaining walls
may be required to facilitate the new site grades and in loading docks. Retaining walls are also
expected within the truck dock areas of the proposed building. The parameters recommended
for use in the design of these walls are presented below.
Retaining Wall Design Parameters
Based on the soil conditions encountered at the boring and trench locations, the following
parameters may be used in the design of new retaining walls for this site. We have provided
parameters assuming the use of on-site soils for retaining wall backfill. The near surface soils
generally consist of silty fine sands and fine to coarse sands with varying amounts of gravel,
cobbles and boulders. Based on their classifications, the sand and silty sand materials are
expected to possess a friction angle of at least 32 degrees when compacted to 90 percent of
the ASTM-1557 maximum dry density.
If desired, SCG could provide design parameters for an alternative select backfill material
behind the retaining walls. The use of select backfill material could result in lower lateral earth
pressures. In order to use the design parameters for the imported select fill, this material must
be placed within the entire active failure wedge. This wedge is defined as extending from the
heel of the retaining wall upwards at an angle of approximately 60° from horizontal. If select
backfill material behind the retaining wall is desired, SCG should be contacted for
supplementary recommendations.
Proposed Industrial Building – Fontana, California Project No. 21G164-1
Page 21
RETAINING WALL DESIGN PARAMETERS
Design Parameter
Soil Type
On-Site
Sands and Silty Sands
Internal Friction Angle () 32
Unit Weight 135 lbs/ft3
Equivalent
Fluid Pressure:
Active Condition
(level backfill) 42 lbs/ft3
Active Condition
(2h:1v backfill) 64 lbs/ft3
At-Rest Condition
(level backfill) 64 lbs/ft3
Regardless of the backfill type, the walls should be designed using a soil-footing coefficient of
friction of 0.30 and an equivalent passive pressure of 300 lbs/ft3. The structural engineer should
incorporate appropriate factors of safety in the design of the retaining walls.
The active earth pressure may be used for the design of retaining walls that do not directly
support structures or support soils that in turn support structures and which will be allowed to
deflect. The at-rest earth pressure should be used for walls that will not be allowed to deflect
such as those which will support foundation bearing soils, or which will support foundation
loads directly.
Where the soils on the toe side of the retaining wall are not covered by a "hard" surface such
as a structure or pavement, the upper 1 foot of soil should be neglected when calculating
passive resistance due to the potential for the material to become disturbed or degraded during
the life of the structure.
Seismic Lateral Earth Pressures
In addition to the lateral earth pressures presented in the previous section, retaining walls
which are more than 6 feet in height should be designed for a seismic lateral earth pressure, in
accordance with the 2019 CBC. Based on the current site plan, it is not expected that any walls
in excess of 6 feet in height will be required for this project. If any such walls are proposed, our
office should be contacted for supplementary design recommendations.
Retaining Wall Foundation Design
The retaining wall foundations should be supported within newly placed compacted structural
fill, extending to a depth of at least 2 feet below the proposed bearing grade. Foundations to
support new retaining walls should be designed in accordance with the general Foundation
Design Parameters presented in a previous section of this report.
Proposed Industrial Building – Fontana, California Project No. 21G164-1
Page 22
Backfill Material
On-site soils may be used to backfill the retaining walls. However, all backfill material
placed within 3 feet of the back wall face should have a particle size no greater than
3 inches. The retaining wall backfill materials should be well graded.
It is recommended that a properly installed prefabricated drainage composite such as the
MiraDRAIN 6000XL (or approved equivalent), which is specifically designed for use behind
retaining walls, be placed against the face of the retaining walls. This drainage composite
should extend from the top of the retaining wall footing to within 1 foot of the ground surface
on the back side of the retaining wall. If the backfill soils are not covered by an impermeable
surface, such as a structure or pavement, a 12-inch thick layer of a low permeability soil should
be placed over the backfill to reduce surface water migration to the underlying soils.
All retaining wall backfill should be placed and compacted under engineering controlled
conditions in the necessary layer thicknesses to ensure an in-place density between 90 and 93
percent of the maximum dry density as determined by the Modified Proctor test (ASTM D1557).
Care should be taken to avoid over-compaction of the soils behind the retaining walls, and the
use of heavy compaction equipment should be avoided.
Subsurface Drainage
As previously indicated, the retaining wall design parameters are based upon drained backfill
conditions. Consequently, some form of permanent drainage system will be necessary in
conjunction with the appropriate backfill material. Subsurface drainage may consist of either:
• A weep hole drainage system typically consisting of a series of 2-inch diameter holes in
the wall situated slightly above the ground surface elevation on the exposed side of the
wall and at an approximate 10-foot on-center spacing. Alternatively, 4-inch diameter
holes at an approximate 20-foot on-center spacing can be used for this type of drainage
system. In addition, the weep holes should include a 2 cubic foot pocket of open graded
gravel, surrounded by an approved geotextile fabric, at each weep hole location.
• A 4-inch diameter perforated pipe surrounded by 2 cubic feet of gravel per linear foot of
drain placed behind the wall, above the retaining wall footing. The gravel layer should
be wrapped in a suitable geotextile fabric to reduce the potential for migration of fines.
The footing drain should be extended to daylight or tied into a storm drainage system.
The actual design of this type of system should be determined by the civil engineer to
verify that the drainage system possesses the adequate capacity and slope for its
intended use.
6.8 Pavement Design Parameters
Site preparation in the pavement area should be completed as previously recommended in the
Site Grading Recommendations section of this report. The subsequent pavement
recommendations assume proper drainage and construction monitoring, and are based on
either PCA or CALTRANS design parameters for a twenty (20) year design period. However,
Proposed Industrial Building – Fontana, California Project No. 21G164-1
Page 23
these designs also assume a routine pavement maintenance program to obtain the anticipated
20-year pavement service life.
Pavement Subgrades
It is anticipated that the new pavements will be primarily supported on a layer of compacted
structural fill, consisting of scarified, thoroughly moisture conditioned and recompacted existing
soils. These materials generally consist of silty fine sands and fine to coarse sands with varying
gravel, cobble and boulder content. Based on their classification, these materials are expected
to possess excellent pavement support characteristics, with estimated R-values greater than 60.
Since R-value testing was not included in the scope of services for this project, the subsequent
pavement design is based upon a conservatively assumed R-value of 60. Any fill material
imported to the site should have support characteristics equal to or greater than that of the on-
site soils and be placed and compacted under engineering controlled conditions. It may be
desirable to perform R-value testing after the completion of rough grading to verify the R-value
of the as-graded parking subgrade.
Asphaltic Concrete
Presented below are the recommended thicknesses for new flexible pavement structures
consisting of asphaltic concrete over a granular base. An alternate pavement section has been
provided for use in parking stall areas due to the anticipated lower traffic intensity in these
areas. However, truck traffic must be excluded from areas where the thinner pavement section
is used; otherwise premature pavement distress may occur. The pavement designs are based
on the traffic indices (TI’s) indicated. The client and/or civil engineer should verify that these
TI’s are representative of the anticipated traffic volumes.
Traffic Index No. of Heavy Trucks per Day
4.0 0
5.0 1
6.0 3
7.0 11
8.0 35
For the purpose of the traffic volumes indicated above, a truck is defined as a 5-axle tractor
trailer unit with one 8-kip axle and two 32-kip tandem axles. All of the traffic indices allow for
1,000 automobiles per day.
Proposed Industrial Building – Fontana, California Project No. 21G164-1
Page 24
ASPHALT PAVEMENTS (R=60)
Materials
Thickness (inches)
Auto Parking and
Auto Drive Lanes
(TI = 4.0 to 5.0)
Truck Traffic
TI = 6.0 TI = 7.0 TI = 8.0 TI = 9.0
Asphalt Concrete 3 3½ 4 5 5½
Aggregate Base 3 3 3 3 4
Compacted Subgrade 12 12 12 12 12
The aggregate base course should be compacted to at least 95 percent of the ASTM D-1557
maximum dry density. The asphaltic concrete should be compacted to at least 95 percent of the
Marshall maximum density, as determined by ASTM D-2726. The aggregate base course may
consist of crushed aggregate base (CAB) or crushed miscellaneous base (CMB), which is a
recycled gravel, asphalt and concrete material. The gradation, R-Value, Sand Equivalent, and
Percentage Wear of the CAB or CMB should comply with appropriate specifications contained in
the current edition of the “Greenbook” Standard Specifications for Public Works Construction.
Portland Cement Concrete
The preparation of the subgrade soils within Portland cement concrete pavement areas should
be performed as previously described for proposed asphalt pavement areas. The minimum
recommended thicknesses for the Portland Cement Concrete pavement sections are as follows:
PORTLAND CEMENT CONCRETE PAVEMENTS (R=60)
Materials
Thickness (inches)
Autos and Light
Truck Traffic
(TI = 6.0)
Truck Traffic
TI = 7.0 TI = 8.0 TI = 9.0
PCC 5 5 6½ 8
Compacted Subgrade
(95% minimum compaction) 12 12 12 12
The concrete should have a 28-day compressive strength of at least 3,000 psi. Reinforcing
within all pavements should be designed by the structural engineer. The maximum joint spacing
within all of the PCC pavements is recommended to be equal to or less than 30 times the
pavement thickness. The actual joint spacing and reinforcing of the Portland cement concrete
pavements should be determined by the structural engineer.
Proposed Industrial Building – Fontana, California Project No. 21G164-1
Page 25
7.0 GENERAL COMMENTS
This report has been prepared as an instrument of service for use by the client, in order to aid
in the evaluation of this property and to assist the architects and engineers in the design and
preparation of the project plans and specifications. This report may be provided to the
contractor(s) and other design consultants to disclose information relative to the project.
However, this report is not intended to be utilized as a specification in and of itself, without
appropriate interpretation by the project architect, civil engineer, and/or structural engineer.
The reproduction and distribution of this report must be authorized by the client and Southern
California Geotechnical, Inc. Furthermore, any reliance on this report by an unauthorized third
party is at such party’s sole risk, and we accept no responsibility for damage or loss which may
occur. The client(s)’ reliance upon this report is subject to the Engineering Services Agreement,
incorporated into our proposal for this project.
The analysis of this site was based on a subsurface profile interpolated from limited discrete soil
samples. While the materials encountered in the project area are considered to be
representative of the total area, some variations should be expected between boring and trench
locations and sample depths. If the conditions encountered during construction vary
significantly from those detailed herein, we should be contacted immediately to determine if the
conditions alter the recommendations contained herein.
This report has been based on assumed or provided characteristics of the proposed
development. It is recommended that the owner, client, architect, structural engineer, and civil
engineer carefully review these assumptions to ensure that they are consistent with the
characteristics of the proposed development. If discrepancies exist, they should be brought to
our attention to verify that they do not affect the conclusions and recommendations contained
herein. We also recommend that the project plans and specifications be submitted to our office
for review to verify that our recommendations have been correctly interpreted.
The analysis, conclusions, and recommendations contained within this report have been
promulgated in accordance with generally accepted professional geotechnical engineering
practice. No other warranty is implied or expressed.
SITE
PROPOSED INDUSTRIAL BUILDING
SCALE: 1" = 2000'
DRAWN: OS
CHKD: RF
SCG PROJECT
21G164-1
PLATE 1
SITE LOCATION MAP
FONTANA, CALIFORNIA
SOURCE: USGS TOPOGRAPHIC MAP OF THE FONTANA
QUADRANGLE, SAN BERNARDINO COUNTY, CALIFORNIA, 2018
B-1B-2B-3B-4T-1T-2T-3T-4SCALE: 1" = 80'DRAWN: MDCHKD: RFPLATE 2SCG PROJECT21G164-1PROPOSED INDUSTRIAL BUILDINGBORING AND TRENCH LOCATION PLANNORTH
SoCalGeoFONTANA, CALIFORNIANOTE: BASE MAP PREPARED BY THIENES ENGINEERING, INC.APPROXIMATE BORING LOCATION GEOTECHNICAL LEGENDAPPROXIMATE TRENCH LOCATION
BORING LOG LEGEND
SAMPLE TYPE GRAPHICAL
SYMBOL SAMPLE DESCRIPTION
AUGER SAMPLE COLLECTED FROM AUGER CUTTINGS, NO FIELD
MEASUREMENT OF SOIL STRENGTH. (DISTURBED)
CORE ROCK CORE SAMPLE: TYPICALLY TAKEN WITH A DIAMOND-TIPPED CORE BARREL. TYPICALLY USED ONLY IN HIGHLY CONSOLIDATED BEDROCK.
GRAB 1
SOIL SAMPLE TAKEN WITH NO SPECIALIZED
EQUIPMENT, SUCH AS FROM A STOCKPILE OR THE GROUND SURFACE. (DISTURBED)
CS CALIFORNIA SAMPLER: 2-1/2 INCH I.D. SPLIT BARREL SAMPLER, LINED WITH 1-INCH HIGH BRASS RINGS.
DRIVEN WITH SPT HAMMER. (RELATIVELY UNDISTURBED)
NSR
NO RECOVERY: THE SAMPLING ATTEMPT DID NOT RESULT IN RECOVERY OF ANY SIGNIFICANT SOIL OR
ROCK MATERIAL.
SPT STANDARD PENETRATION TEST: SAMPLER IS A 1.4 INCH INSIDE DIAMETER SPLIT BARREL, DRIVEN 18 INCHES WITH THE SPT HAMMER. (DISTURBED)
SH SHELBY TUBE: TAKEN WITH A THIN WALL SAMPLE
TUBE, PUSHED INTO THE SOIL AND THEN EXTRACTED. (UNDISTURBED)
VANE VANE SHEAR TEST: SOIL STRENGTH OBTAINED USING A 4 BLADED SHEAR DEVICE. TYPICALLY USED IN SOFT CLAYS-NO SAMPLE RECOVERED.
COLUMN DESCRIPTIONS
DEPTH: Distance in feet below the ground surface.
SAMPLE: Sample Type as depicted above.
BLOW COUNT: Number of blows required to advance the sampler 12 inches using a 140 lb
hammer with a 30-inch drop. 50/3” indicates penetration refusal (>50 blows)
at 3 inches. WH indicates that the weight of the hammer was sufficient to
push the sampler 6 inches or more.
POCKET PEN.: Approximate shear strength of a cohesive soil sample as measured by pocket
penetrometer.
GRAPHIC LOG: Graphic Soil Symbol as depicted on the following page.
DRY DENSITY: Dry density of an undisturbed or relatively undisturbed sample in lbs/ft3.
MOISTURE CONTENT: Moisture content of a soil sample, expressed as a percentage of the dry weight.
LIQUID LIMIT: The moisture content above which a soil behaves as a liquid.
PLASTIC LIMIT: The moisture content above which a soil behaves as a plastic.
PASSING #200 SIEVE: The percentage of the sample finer than the #200 standard sieve.
UNCONFINED SHEAR: The shear strength of a cohesive soil sample, as measured in the unconfined state.
SM
SP
COARSE
GRAINEDSOILS
SW
TYPICAL
DESCRIPTIONS
WELL-GRADED GRAVELS, GRAVEL -
SAND MIXTURES, LITTLE OR NOFINES
SILTY GRAVELS, GRAVEL - SAND -
SILT MIXTURES
LETTERGRAPH
POORLY-GRADED GRAVELS,
GRAVEL - SAND MIXTURES, LITTLEOR NO FINES
GC
GM
GP
GW
POORLY-GRADED SANDS,
GRAVELLY SAND, LITTLE OR NOFINES
SILTSAND
CLAYS
MORE THAN 50%
OF MATERIAL ISLARGER THANNO. 200 SIEVE
SIZE
MORE THAN 50%OF MATERIAL IS
SMALLER THANNO. 200 SIEVESIZE
MORE THAN 50%OF COARSEFRACTION
PASSING ON NO.4 SIEVE
MORE THAN 50%OF COARSE
FRACTIONRETAINED ON NO.4 SIEVE CLAYEY GRAVELS, GRAVEL - SAND -
CLAY MIXTURES
FINEGRAINED
SOILS
SYMBOLSMAJOR DIVISIONS
SOIL CLASSIFICATION CHART
PT
OH
CH
MH
OL
CL
ML
CLEAN SANDS
SC
SILTY SANDS, SAND - SILTMIXTURES
CLAYEY SANDS, SAND - CLAY
MIXTURES
INORGANIC SILTS AND VERY FINESANDS, ROCK FLOUR, SILTY OR
CLAYEY FINE SANDS OR CLAYEYSILTS WITH SLIGHT PLASTICITY
INORGANIC CLAYS OF LOW TO
MEDIUM PLASTICITY, GRAVELLYCLAYS, SANDY CLAYS, SILTY CLAYS,LEAN CLAYS
ORGANIC SILTS AND ORGANICSILTY CLAYS OF LOW PLASTICITY
INORGANIC SILTS, MICACEOUS OR
DIATOMACEOUS FINE SAND ORSILTY SOILS
INORGANIC CLAYS OF HIGH
PLASTICITY
ORGANIC CLAYS OF MEDIUM TO
HIGH PLASTICITY, ORGANIC SILTS
PEAT, HUMUS, SWAMP SOILS WITHHIGH ORGANIC CONTENTS
SILTS
AND
CLAYS
GRAVELS WITH
FINES
SAND
AND
SANDY
SOILS (LITTLE OR NO FINES)
SANDS WITH
FINES
LIQUID LIMITLESS THAN 50
LIQUID LIMIT
GREATER THAN 50
HIGHLY ORGANIC SOILS
NOTE: DUAL SYMBOLS ARE USED TO INDICATE BORDERLINE SOIL CLASSIFICATIONS
GRAVEL
AND
GRAVELLYSOILS
(APPRECIABLE
AMOUNT OF FINES)
(APPRECIABLE
AMOUNT OF FINES)
(LITTLE OR NO FINES)
WELL-GRADED SANDS, GRAVELLYSANDS, LITTLE OR NO FINES
CLEAN
GRAVELS
ALLUVIUM: Gray Brown Silty fine to coarse Sand, little fine to
coarse Gravel, occasional Cobbles, dense-dry
Light Gray Brown Gravelly fine to coarse Sand, occasional to
extensive Cobbles, occasional Boulders, dense to very
dense-dry to damp
Boring Terminated at 16½' due to refusal on extensive cobbles
No Sample
Recovery
Disturbed
Sample
50
54
75/10"
50/3"
50/4"
50/4"
92
119
128
1
1
2
1
1DRY DENSITY(PCF)DEPTH (FEET)MOISTURECONTENT (%)JOB NO.: 21G164-1
PROJECT: Proposed Industrial Building
LOCATION: Fontana, California
PLATE B-1
5
10
15
LABORATORY RESULTS
COMMENTSBORING NO.
B-1
WATER DEPTH: Dry
CAVE DEPTH: 1 foot
READING TAKEN: ---PASSING#200 SIEVE (%)BLOW COUNTDESCRIPTION
SURFACE ELEVATION: --- MSL LIQUIDLIMITPLASTICLIMITSAMPLEFIELD RESULTS
GRAPHIC LOGPOCKET PEN.(TSF)DRILLING DATE: 4/30/21
DRILLING METHOD: Hollow Stem Auger
LOGGED BY: Daryl Kas
TEST BORING LOG ORGANICCONTENT (%)TBL 21G164-1.GPJ SOCALGEO.GDT 5/25/21
39
48
50/4"
30
50/3"
1
1
1
2
2
ALLUVIUM: Gray Brown Silty fine to coarse Sand, little fine to
coarse Gravel, dense-dry
Light Gray Brown Gravelly fine to coarse Sand, occasional to
extensive Cobbles, occasional Boulders, dense to very
dense-dry to damp
Boring Terminated at 15'DRY DENSITY(PCF)DEPTH (FEET)MOISTURECONTENT (%)JOB NO.: 21G164-1
PROJECT: Proposed Industrial Building
LOCATION: Fontana, California
PLATE B-2
5
10
15
DESCRIPTION
SURFACE ELEVATION: --- MSL LIQUIDLIMITPLASTICLIMITSAMPLEFIELD RESULTS
GRAPHIC LOGPOCKET PEN.(TSF)DRILLING DATE: 4/30/21
DRILLING METHOD: Hollow Stem Auger
LOGGED BY: Daryl Kas
TEST BORING LOG ORGANICCONTENT (%)WATER DEPTH: Dry
CAVE DEPTH: 5 feet
READING TAKEN: ---
LABORATORY RESULTS
COMMENTSBORING NO.
B-2
PASSING#200 SIEVE (%)BLOW COUNTTBL 21G164-1.GPJ SOCALGEO.GDT 5/25/21
79/9"
40
100/7"
50/2"
92/7"
66/11"
106
100
112
112
1
1
1
1
1
1
ALLUVIUM: Gray Brown Silty fine to coarse Sand, little fine to
coarse Gravel, occasional Cobbles, trace fine root fibers,
medium dense to very dense-dry
Light Gray Gravelly fine to coarse Sand, occasional to
extensive Cobbles, occasional Boulders, medium dense to
very dense-dry
Light Gray Brown fine to coarse Gravel, occasional to
extensive Cobbles, occasional Boulders, very dense-dry
Light Gray Brown Gravelly fine to coarse Sand, occasional to
extensive Cobbles, occasional Boulders, very dense-dry
Boring Terminated at 15'
Disturbed
SampleDRY DENSITY(PCF)DEPTH (FEET)MOISTURECONTENT (%)JOB NO.: 21G164-1
PROJECT: Proposed Industrial Building
LOCATION: Fontana, California
PLATE B-3
5
10
15
DESCRIPTION
SURFACE ELEVATION: --- MSL LIQUIDLIMITPLASTICLIMITSAMPLEFIELD RESULTS
GRAPHIC LOGPOCKET PEN.(TSF)DRILLING DATE: 4/30/21
DRILLING METHOD: Hollow Stem Auger
LOGGED BY: Daryl Kas
TEST BORING LOG ORGANICCONTENT (%)WATER DEPTH: Dry
CAVE DEPTH: 4 feet
READING TAKEN: ---
LABORATORY RESULTS
COMMENTSBORING NO.
B-3
PASSING#200 SIEVE (%)BLOW COUNTTBL 21G164-1.GPJ SOCALGEO.GDT 5/25/21
35
28
66/11"
81/11"
81/11"
81/8"
1
1
1
1
2
2
ALLUVIUM: Brown Silty fine to coarse Sand, little fine to
coarse Gravel, dense-dry
Light Gray Brown Gravelly fine to coarse Sand, occasional to
extensive Cobbles, occasional Boulders, medium dense-dry
Brown fine to coarse Gravel, occasional to extensive Cobbles,
occasional Boulders, very dense-dry
Gray Brown Gravelly fine to coarse Sand, occasional to
extensive Cobbles, occasional Boulders, very dense-dry to
damp
Boring Terminated at 20'DRY DENSITY(PCF)DEPTH (FEET)MOISTURECONTENT (%)JOB NO.: 21G164-1
PROJECT: Proposed Industrial Building
LOCATION: Fontana, California
PLATE B-4
5
10
15
20
DESCRIPTION
SURFACE ELEVATION: --- MSL LIQUIDLIMITPLASTICLIMITSAMPLEFIELD RESULTS
GRAPHIC LOGPOCKET PEN.(TSF)DRILLING DATE: 4/30/21
DRILLING METHOD: Hollow Stem Auger
LOGGED BY: Daryl Kas
TEST BORING LOG ORGANICCONTENT (%)WATER DEPTH: Dry
CAVE DEPTH: 10 feet
READING TAKEN: ---
LABORATORY RESULTS
COMMENTSBORING NO.
B-4
PASSING#200 SIEVE (%)BLOW COUNTTBL 21G164-1.GPJ SOCALGEO.GDT 5/25/21
SOUTHERN CALIFORNIA GEOTECHNICALPLATE B-1TRENCH NO.T-1DEPTHSAMPLEDRY DENSITY(PCF)MOISTURE (%)EARTH MATERIALSDESCRIPTIONGRAPHIC REPRESENTATION51015SCALE: 1" = 5'TRENCH LOGKEY TO SAMPLE TYPES:B - BULK SAMPLE (DISTURBED)R - RING SAMPLE 2-1/2" DIAMETER (RELATIVELY UNDISTURBED)WATER DEPTH: DrySEEPAGE DEPTH: DryREADINGS TAKEN: At CompletionA: ALLUVIUM: Gray Brown Silty fine to coarse Sand, trace to little fine tocoarse Gravel, trace fine root fibers, loose to medium dense-dryB: Light Gray Brown to coarse Sandy Gravel, extensive Cobbles,occasional Boulders, dense-dryC: Light Gray Brown Gravelly fine to coarse Sand, occasional toextensive Cobbles, occasional Boulders, dense-dry to dampN 24 EJOB NO.: 21G164-1PROJECT: Proposed Industrial BuildingLOCATION: Fontana, CaliforniaDATE: 4/30/2021Trench Terminated @ 9 feetAbEQUIPMENT USED: BackhoeLOGGED BY: Daryl KasORIENTATION: N 24 EELEVATION: ---1Bb2b2CBoulderBoulderCobbles
SOUTHERN CALIFORNIA GEOTECHNICALPLATE B-2TRENCH NO.T-2DEPTHSAMPLEDRY DENSITY(PCF)MOISTURE (%)EARTH MATERIALSDESCRIPTIONGRAPHIC REPRESENTATION51015SCALE: 1" = 5'TRENCH LOGKEY TO SAMPLE TYPES:B - BULK SAMPLE (DISTURBED)R - RING SAMPLE 2-1/2" DIAMETER (RELATIVELY UNDISTURBED)WATER DEPTH: DrySEEPAGE DEPTH: DryREADINGS TAKEN: At CompletionA: ALLUVIUM: Dark Gray Brown Silty fine to coarse Sand, little fine tocoarse Gravel, trace fine root fibers, loose-dryB: Light Gray Brown fine to coarse Sandy Gravel, extensive Cobbles,occasional Boulders, dense-dry to dampC: Light Gray Brown Gravelly fine to coarse Sand, occasional Cobbles,occasional Boulders, dense-dry to dampN 45 ETrench Terminated @ 9 feetEQUIPMENT USED: BackhoeLOGGED BY: Daryl KasORIENTATION: N 45 EELEVATION: ---b2b1b2JOB NO.: 21G164-1PROJECT: Proposed Industrial BuildingLOCATION: Fontana, CaliforniaDATE: 4/30/2021Cobblesb2ABCBoulders
SOUTHERN CALIFORNIA GEOTECHNICALPLATE B-3TRENCH NO.T-3DEPTHSAMPLEDRY DENSITY(PCF)MOISTURE (%)EARTH MATERIALSDESCRIPTIONGRAPHIC REPRESENTATION51015SCALE: 1" = 5'TRENCH LOGKEY TO SAMPLE TYPES:B - BULK SAMPLE (DISTURBED)R - RING SAMPLE 2-1/2" DIAMETER (RELATIVELY UNDISTURBED)WATER DEPTH: DrySEEPAGE DEPTH: DryREADINGS TAKEN: At CompletionA: ALLUVIUM: Dark Gray Brown Silty fine to coarse Sand, trace to littlefine to coarse Gravel, trace fine root fibers, loose-dryB: Light Gray Brown fine to coarse Sandy Gravel, occasional Cobbles,occasional Boulders, dense-dryN 33 WRefusal @ 5 feet due to severe cavingABEQUIPMENT USED: BackhoeLOGGED BY: Daryl KasORIENTATION: N 33 WELEVATION: ---b1b1b1JOB NO.: 21G164-1PROJECT: Proposed Industrial BuildingLOCATION: Fontana, CaliforniaDATE: 4/30/2021CobbleBoulder
ABSOUTHERN CALIFORNIA GEOTECHNICALPLATE B-4TRENCH NO.T-4DEPTHSAMPLEDRY DENSITY(PCF)MOISTURE (%)EARTH MATERIALSDESCRIPTIONGRAPHIC REPRESENTATION51015SCALE: 1" = 5'TRENCH LOGKEY TO SAMPLE TYPES:B - BULK SAMPLE (DISTURBED)R - RING SAMPLE 2-1/2" DIAMETER (RELATIVELY UNDISTURBED)WATER DEPTH: DrySEEPAGE DEPTH: DryREADINGS TAKEN: At CompletionA: ALLUVIUM: Dark Gray Brown Silty fine to coarse Sand, trace fine tocoarse Gravel, trace fine root fibers, loose-dryB: Light Gray Brown fine to coarse Sandy Gravel, extensive Cobbles,occasional Boulders, dense-dampC: Light Gray Brown Gravelly fine to coarse Sand, occasional Cobbles,dense-dry to dampN 20 EbEQUIPMENT USED: BackhoeLOGGED BY: Daryl KasORIENTATION: N 20 EELEVATION: ---3b3CTrench Terminated @ 9.5 feetJOB NO.: 21G164-1PROJECT: Proposed Industrial BuildingLOCATION: Fontana, CaliforniaDATE: 4/30/2021CobblesBoulderb2b1
Classification: Gray Brown Silty fine to coarse Sand, little fine to coarse Gravel
Boring Number:B-3 Initial Moisture Content (%)1
Sample Number:---Final Moisture Content (%)14
Depth (ft)1 to 2 Initial Dry Density (pcf)106.3
Specimen Diameter (in)2.4 Final Dry Density (pcf)114.5
Specimen Thickness (in)1.0 Percent Collapse (%)0.54
Proposed Industrial Building
Fontana, CA
Project No. 21G164-1
PLATE C- 1
0
2
4
6
8
10
12
14
16
18
20
0.1 1 10 100ConsolidationStrain(%)Load (ksf)
Consolidation/Collapse Test Results
Water Added
at 1600 psf
Classification: Gray Brown Silty fine to coarse Sand, little fine to coarse Gravel
Boring Number:B-3 Initial Moisture Content (%)1
Sample Number:---Final Moisture Content (%)14
Depth (ft)3 to 4 Initial Dry Density (pcf)100.1
Specimen Diameter (in)2.4 Final Dry Density (pcf)108.1
Specimen Thickness (in)1.0 Percent Collapse (%)1.48
Proposed Industrial Building
Fontana, CA
Project No. 21G164-1
PLATE C- 2
0
2
4
6
8
10
12
14
16
18
20
0.1 1 10 100ConsolidationStrain(%)Load (ksf)
Consolidation/Collapse Test Results
Water Added
at 1600 psf
Classification: Light Gray Gravelly fine to coarse Sand
Boring Number:B-3 Initial Moisture Content (%)1
Sample Number:---Final Moisture Content (%)10
Depth (ft)5 to 6 Initial Dry Density (pcf)112.2
Specimen Diameter (in)2.4 Final Dry Density (pcf)117.2
Specimen Thickness (in)1.0 Percent Collapse (%)0.49
Proposed Industrial Building
Fontana, CA
Project No. 21G164-1
PLATE C- 3
0
2
4
6
8
10
12
14
16
18
20
0.1 1 10 100ConsolidationStrain(%)Load (ksf)
Consolidation/Collapse Test Results
Water Added
at 1600 psf
Classification: Light Gray Brown Gravelly fine to coarse Sand
Boring Number:B-3 Initial Moisture Content (%)1
Sample Number:---Final Moisture Content (%)12
Depth (ft)9 to 10 Initial Dry Density (pcf)112.0
Specimen Diameter (in)2.4 Final Dry Density (pcf)116.4
Specimen Thickness (in)1.0 Percent Collapse (%)0.15
Proposed Industrial Building
Fontana, CA
Project No. 21G164-1
PLATE C- 4
0
2
4
6
8
10
12
14
16
18
20
0.1 1 10 100ConsolidationStrain(%)Load (ksf)
Consolidation/Collapse Test Results
Water Added
at 1600 psf
Proposed Industrial Building
Fontana, California
Project No. 21G164-1
PLATE C-5
120
122
124
126
128
130
132
134
136
138
140
142
144
146
0 2 4 6 8 10 12 14 16DryDensity(lbs/ft3)Moisture Content (%)
Moisture/Density Relationship
ASTM D-1557
Soil ID Number B-3
Optimum Moisture (%)5
Maximum Dry Density (pcf)139
Soil
Classification Light Gray Gravelly fine to coarse
Sand, extensive Cobbles
Zero Air Voids Curve:
Specific Gravity = 2.7
Note: Maximum Density
and Optimum Moisture are
based on 25% rock
correction.
Grading Guide Specifications Page 1
GRADING GUIDE SPECIFICATIONS
These grading guide specifications are intended to provide typical procedures for grading operations.
They are intended to supplement the recommendations contained in the geotechnical investigation
report for this project. Should the recommendations in the geotechnical investigation report conflict
with the grading guide specifications, the more site specific recommendations in the geotechnical
investigation report will govern.
General
• The Earthwork Contractor is responsible for the satisfactory completion of all earthwork in
accordance with the plans and geotechnical reports, and in accordance with city, county,
and applicable building codes.
• The Geotechnical Engineer is the representative of the Owner/Builder for the purpose of
implementing the report recommendations and guidelines. These duties are not intended to
relieve the Earthwork Contractor of any responsibility to perform in a workman-like manner,
nor is the Geotechnical Engineer to direct the grading equipment or personnel employed by
the Contractor.
• The Earthwork Contractor is required to notify the Geotechnical Engineer of the anticipated
work and schedule so that testing and inspections can be provided. If necessary, work may
be stopped and redone if personnel have not been scheduled in advance.
• The Earthwork Contractor is required to have suitable and sufficient equipment on the job-
site to process, moisture condition, mix and compact the amount of fill being placed to the
approved compaction. In addition, suitable support equipment should be available to
conform with recommendations and guidelines in this report.
• Canyon cleanouts, overexcavation areas, processed ground to receive fill, key excavations,
subdrains and benches should be observed by the Geotechnical Engineer prior to placement
of any fill. It is the Earthwork Contractor's responsibility to notify the Geotechnical Engineer
of areas that are ready for inspection.
• Excavation, filling, and subgrade preparation should be performed in a manner and
sequence that will provide drainage at all times and proper control of erosion. Precipitation,
springs, and seepage water encountered shall be pumped or drained to provide a suitable
working surface. The Geotechnical Engineer must be informed of springs or water seepage
encountered during grading or foundation construction for possible revision to the
recommended construction procedures and/or installation of subdrains.
Site Preparation
• The Earthwork Contractor is responsible for all clearing, grubbing, stripping and site
preparation for the project in accordance with the recommendations of the Geotechnical
Engineer.
• If any materials or areas are encountered by the Earthwork Contractor which are suspected
of having toxic or environmentally sensitive contamination, the Geotechnical Engineer and
Owner/Builder should be notified immediately.
Grading Guide Specifications Page 2
• Major vegetation should be stripped and disposed of off-site. This includes trees, brush,
heavy grasses and any materials considered unsuitable by the Geotechnical Engineer.
• Underground structures such as basements, cesspools or septic disposal systems, mining
shafts, tunnels, wells and pipelines should be removed under the inspection of the
Geotechnical Engineer and recommendations provided by the Geotechnical Engineer and/or
city, county or state agencies. If such structures are known or found, the Geotechnical
Engineer should be notified as soon as possible so that recommendations can be
formulated.
• Any topsoil, slopewash, colluvium, alluvium and rock materials which are considered
unsuitable by the Geotechnical Engineer should be removed prior to fill placement.
• Remaining voids created during site clearing caused by removal of trees, foundations
basements, irrigation facilities, etc., should be excavated and filled with compacted fill.
• Subsequent to clearing and removals, areas to receive fill should be scarified to a depth of
10 to 12 inches, moisture conditioned and compacted
• The moisture condition of the processed ground should be at or slightly above the optimum
moisture content as determined by the Geotechnical Engineer. Depending upon field
conditions, this may require air drying or watering together with mixing and/or discing.
Compacted Fills
• Soil materials imported to or excavated on the property may be utilized in the fill, provided
each material has been determined to be suitable in the opinion of the Geotechnical
Engineer. Unless otherwise approved by the Geotechnical Engineer, all fill materials shall be
free of deleterious, organic, or frozen matter, shall contain no chemicals that may result in
the material being classified as “contaminated,” and shall be very low to non-expansive with
a maximum expansion index (EI) of 50. The top 12 inches of the compacted fill should
have a maximum particle size of 3 inches, and all underlying compacted fill material a
maximum 6-inch particle size, except as noted below.
• All soils should be evaluated and tested by the Geotechnical Engineer. Materials with high
expansion potential, low strength, poor gradation or containing organic materials may
require removal from the site or selective placement and/or mixing to the satisfaction of the
Geotechnical Engineer.
• Rock fragments or rocks less than 6 inches in their largest dimensions, or as otherwise
determined by the Geotechnical Engineer, may be used in compacted fill, provided the
distribution and placement is satisfactory in the opinion of the Geotechnical Engineer.
• Rock fragments or rocks greater than 12 inches should be taken off-site or placed in
accordance with recommendations and in areas designated as suitable by the Geotechnical
Engineer. These materials should be placed in accordance with Plate D-8 of these Grading
Guide Specifications and in accordance with the following recommendations:
• Rocks 12 inches or more in diameter should be placed in rows at least 15 feet apart, 15
feet from the edge of the fill, and 10 feet or more below subgrade. Spaces should be
left between each rock fragment to provide for placement and compaction of soil
around the fragments.
• Fill materials consisting of soil meeting the minimum moisture content requirements and
free of oversize material should be placed between and over the rows of rock or
Grading Guide Specifications Page 3
concrete. Ample water and compactive effort should be applied to the fill materials as
they are placed in order that all of the voids between each of the fragments are filled
and compacted to the specified density.
• Subsequent rows of rocks should be placed such that they are not directly above a row
placed in the previous lift of fill. A minimum 5-foot offset between rows is
recommended.
• To facilitate future trenching, oversized material should not be placed within the range
of foundation excavations, future utilities or other underground construction unless
specifically approved by the soil engineer and the developer/owner representative.
• Fill materials approved by the Geotechnical Engineer should be placed in areas previously
prepared to receive fill and in evenly placed, near horizontal layers at about 6 to 8 inches in
loose thickness, or as otherwise determined by the Geotechnical Engineer for the project.
• Each layer should be moisture conditioned to optimum moisture content, or slightly above,
as directed by the Geotechnical Engineer. After proper mixing and/or drying, to evenly
distribute the moisture, the layers should be compacted to at least 90 percent of the
maximum dry density in compliance with ASTM D-1557-78 unless otherwise indicated.
• Density and moisture content testing should be performed by the Geotechnical Engineer at
random intervals and locations as determined by the Geotechnical Engineer. These tests
are intended as an aid to the Earthwork Contractor, so he can evaluate his workmanship,
equipment effectiveness and site conditions. The Earthwork Contractor is responsible for
compaction as required by the Geotechnical Report(s) and governmental agencies.
• Fill areas unused for a period of time may require moisture conditioning, processing and
recompaction prior to the start of additional filling. The Earthwork Contractor should notify
the Geotechnical Engineer of his intent so that an evaluation can be made.
• Fill placed on ground sloping at a 5-to-1 inclination (horizontal-to-vertical) or steeper should
be benched into bedrock or other suitable materials, as directed by the Geotechnical
Engineer. Typical details of benching are illustrated on Plates D-2, D-4, and D-5.
• Cut/fill transition lots should have the cut portion overexcavated to a depth of at least 3 feet
and rebuilt with fill (see Plate D-1), as determined by the Geotechnical Engineer.
• All cut lots should be inspected by the Geotechnical Engineer for fracturing and other
bedrock conditions. If necessary, the pads should be overexcavated to a depth of 3 feet
and rebuilt with a uniform, more cohesive soil type to impede moisture penetration.
• Cut portions of pad areas above buttresses or stabilizations should be overexcavated to a
depth of 3 feet and rebuilt with uniform, more cohesive compacted fill to impede moisture
penetration.
• Non-structural fill adjacent to structural fill should typically be placed in unison to provide
lateral support. Backfill along walls must be placed and compacted with care to ensure that
excessive unbalanced lateral pressures do not develop. The type of fill material placed
adjacent to below grade walls must be properly tested and approved by the Geotechnical
Engineer with consideration of the lateral earth pressure used in the design.
Grading Guide Specifications Page 4
Foundations
• The foundation influence zone is defined as extending one foot horizontally from the outside
edge of a footing, and proceeding downward at a ½ horizontal to 1 vertical (0.5:1)
inclination.
• Where overexcavation beneath a footing subgrade is necessary, it should be conducted so
as to encompass the entire foundation influence zone, as described above.
• Compacted fill adjacent to exterior footings should extend at least 12 inches above
foundation bearing grade. Compacted fill within the interior of structures should extend to
the floor subgrade elevation.
Fill Slopes
• The placement and compaction of fill described above applies to all fill slopes. Slope
compaction should be accomplished by overfilling the slope, adequately compacting the fill
in even layers, including the overfilled zone and cutting the slope back to expose the
compacted core
• Slope compaction may also be achieved by backrolling the slope adequately every 2 to 4
vertical feet during the filling process as well as requiring the earth moving and compaction
equipment to work close to the top of the slope. Upon completion of slope construction,
the slope face should be compacted with a sheepsfoot connected to a sideboom and then
grid rolled. This method of slope compaction should only be used if approved by the
Geotechnical Engineer.
• Sandy soils lacking in adequate cohesion may be unstable for a finished slope condition and
therefore should not be placed within 15 horizontal feet of the slope face.
• All fill slopes should be keyed into bedrock or other suitable material. Fill keys should be at
least 15 feet wide and inclined at 2 percent into the slope. For slopes higher than 30 feet,
the fill key width should be equal to one-half the height of the slope (see Plate D-5).
• All fill keys should be cleared of loose slough material prior to geotechnical inspection and
should be approved by the Geotechnical Engineer and governmental agencies prior to filling.
• The cut portion of fill over cut slopes should be made first and inspected by the
Geotechnical Engineer for possible stabilization requirements. The fill portion should be
adequately keyed through all surficial soils and into bedrock or suitable material. Soils
should be removed from the transition zone between the cut and fill portions (see Plate D-
2).
Cut Slopes
• All cut slopes should be inspected by the Geotechnical Engineer to determine the need for
stabilization. The Earthwork Contractor should notify the Geotechnical Engineer when slope
cutting is in progress at intervals of 10 vertical feet. Failure to notify may result in a delay
in recommendations.
• Cut slopes exposing loose, cohesionless sands should be reported to the Geotechnical
Engineer for possible stabilization recommendations.
• All stabilization excavations should be cleared of loose slough material prior to geotechnical
inspection. Stakes should be provided by the Civil Engineer to verify the location and
dimensions of the key. A typical stabilization fill detail is shown on Plate D-5.
Grading Guide Specifications Page 5
• Stabilization key excavations should be provided with subdrains. Typical subdrain details
are shown on Plates D-6.
Subdrains
• Subdrains may be required in canyons and swales where fill placement is proposed. Typical
subdrain details for canyons are shown on Plate D-3. Subdrains should be installed after
approval of removals and before filling, as determined by the Soils Engineer.
• Plastic pipe may be used for subdrains provided it is Schedule 40 or SDR 35 or equivalent.
Pipe should be protected against breakage, typically by placement in a square-cut
(backhoe) trench or as recommended by the manufacturer.
• Filter material for subdrains should conform to CALTRANS Specification 68-1.025 or as
approved by the Geotechnical Engineer for the specific site conditions. Clean ¾-inch
crushed rock may be used provided it is wrapped in an acceptable filter cloth and approved
by the Geotechnical Engineer. Pipe diameters should be 6 inches for runs up to 500 feet
and 8 inches for the downstream continuations of longer runs. Four-inch diameter pipe
may be used in buttress and stabilization fills.
GRADING GUIDE SPECIFICATIONS
NOT TO SCALE
DRAWN: JAS
CHKD: GKM
PLATE D-2
FILL ABOVE CUT SLOPE DETAIL
9' MIN.
4' TYP.
MINIMUM 1' TILT BACK
OR 2% SLOPE
(WHICHEVER IS GREATER)
REMOVE U
N
S
U
I
T
A
B
L
E
M
A
T
E
R
I
A
L
BENCHING DIMENSIONS IN ACCORDANCE
WITH PLAN OR AS RECOMMENDED
BY THE GEOTECHNICAL ENGINEER
CUT SLOPE TO BE CONSTRUCTED
PRIOR TO PLACEMENT OF FILL
BEDROCK OR APPROVED
COMPETENT MATERIAL
CUT SLOPE
NATURAL GRADE
CUT/FILL CONTACT TO BE
SHOWN ON "AS-BUILT"
COMPETENT MATERIAL CUT/FILL CONTACT SHOWN
ON GRADING PLAN
NEW COMPACTED FILL
10' TYP.
KEYWAY IN COMPETENT MATERIAL
MINIMUM WIDTH OF 15 FEET OR AS
RECOMMENDED BY THE GEOTECHNICAL
ENGINEER. KEYWAY MAY NOT BE
REQUIRED IF FILL SLOPE IS LESS THAN 5
FEET IN HEIGHT AS RECOMMENDED BY
THE GEOTECHNICAL ENGINEER.
GRADING GUIDE SPECIFICATIONS
NOT TO SCALE
DRAWN: JAS
CHKD: GKM
PLATE D-4
FILL ABOVE NATURAL SLOPE DETAIL
10' TYP.4' TYP.
(WHICHEVER IS GREATER)
OR 2% SLOPE
MINIMUM 1' TILT BACK
REMOVE UN
S
U
I
T
A
B
L
E
M
A
T
E
R
I
A
L
NEW COMPACTED FILL
COMPETENT MATERIAL
KEYWAY IN COMPETENT MATERIAL.
RECOMMENDED BY THE GEOTECHNIAL
ENGINEER. KEYWAY MAY NOT BE REQUIRED
IF FILL SLOPE IS LESS THAN 5' IN HEIGHT
AS RECOMMENDED BY THE GEOTECHNICAL
ENGINEER.
2' MINIMUM
KEY DEPTH
OVERFILL REQUIREMENTS
PER GRADING GUIDE SPECIFICATIONS
TOE OF SLOPE SHOWN
ON GRADING PLAN
BACKCUT - VARIES
PLACE COMPACTED BACKFILL
TO ORIGINAL GRADE
PROJECT SLOPE GRADIENT
(1:1 MAX.)
NOTE:
BENCHING SHALL BE REQUIRED
WHEN NATURAL SLOPES ARE
EQUAL TO OR STEEPER THAN 5:1
OR WHEN RECOMMENDED BY
THE GEOTECHNICAL ENGINEER.
FINISHED SLOPE FACE
MINIMUM WIDTH OF 15 FEET OR AS
BENCHING DIMENSIONS IN ACCORDANCE
WITH PLAN OR AS RECOMMENDED
BY THE GEOTECHNICAL ENGINEER
GRADING GUIDE SPECIFICATIONS
NOT TO SCALE
DRAWN: JAS
CHKD: GKM
PLATE D-5
STABILIZATION FILL DETAIL
FACE OF FINISHED SLOPE
COMPACTED FILL
MINIMUM 1' TILT BACK
OR 2% SLOPE
(WHICHEVER IS GREATER)
10' TYP.
2' MINIMUM
KEY DEPTH
3' TYPICAL
BLANKET FILL IF RECOMMENDED
BY THE GEOTECHNICAL ENGINEER
COMPETENT MATERIAL ACCEPTABLE
TO THE SOIL ENGINEER
KEYWAY WIDTH, AS SPECIFIED
BY THE GEOTECHNICAL ENGINEER
TOP WIDTH OF FILL
AS SPECIFIED BY THE
GEOTECHNICAL ENGINEER
BENCHING DIMENSIONS IN ACCORDANCE
WITH PLAN OR AS RECOMMENDED
BY THE GEOTECHNICAL ENGINEER
4' TYP.
PROPOSED INDUSTRIAL BUILDING
DRAWN: RF
CHKD: RGT
SCG PROJECT
21G164-1
PLATE E-1
SEISMIC DESIGN PARAMETERS - 2019 CBC
FONTANA, CALIFORNIA
SOURCE: SEAOC/OSHPD Seismic Design Maps Tool
<https://seismicmaps.org/>