HomeMy WebLinkAboutAppendix D - Geotechnical Engineering InvestigationMDN 24446
GEOLOGIC AND GEOTECHNICAL ENGINEERING DUE DILIGENCE
INVESTIGATION, PROPOSED 36 LOT PLANNED DEVELOPMENT,
7844 Citrus Avenue,
Fontana, California
for
Ridge Crest Real Estate, LLC
October 29, 2024 W.O. 8003
GeoSoils Consultants Inc.
MDN 24446
6634 Valjean Avenue, Van Nuys, California 91406 Phone: (818) 785-2158 Fax: (818) 785-1548
October 29, 2024
W.O. 8003
RIDGE CREST REAL ESTATE, LLC
550 North Larchmont Boulevard, Suite 201
Los Angeles, California 90004
Attention: Mr. John Fitzpatrick
Subject: Geologic and Geotechnical Engineering Due Diligence
Investigation, Proposed 36 Lot Planned Development, 7844
Citrus Avenue, Fontana, California
Dear Mr. Fitzpatrick:
As requested, GeoSoils Consultants, Inc. (GSC) has conducted a geologic and geotechnical
engineering due diligence investigation for the subject property. The purpose of this investigation
is to determine the general geologic and geotechnical engineering conditions on the site and their
potential impact on the proposed development. The report presents the results of our research,
subsurface exploration, laboratory testing, and engineering analyses.
Grading of the site is considered feasible from a geologic and geotechnical engineering
perspective, provided the constraints and recommendations presented herein are taken into
consideration and incorporated into the design. The primary geologic/geotechnical constraints
consist of a high percentage of rocks in the upper soil zone and low moisture content of the soil.
Removals of unsuitable soil shall extend five feet below existing or proposed grades, whichever
is deeper.
We appreciate this opportunity to be of service to you. If you have any questions regarding this
report, or if we may be of further assistance to you, please do not hesitate to contact us.
Very truly yours,
GEOSOILS CONSULTANTS, INC.
RUDY F. RUBERTI KAREN L. MILLER
CEG 1708 GE 2257
cc: (1) Addressee
oSoils Consultants Inc.
GEOTECHNICAL ENGINEERING / ENGINEERING GEOLOGY
3/31/26
MDN 24446
6634 Valjean Avenue, Van Nuys, California 91406 Phone: (818) 785-2158 Fax: (818) 785-1548
October 29, 2024
W.O. 8003
TABLE OF CONTENTS
1.0 INTRODUCTION .................................................................................................... 1
1.1 Scope of Services ............................................................................................................. 1
1.2 Site Description ................................................................................................................ 2
1.3 Proposed Development .................................................................................................... 2
1.4 Limitations ....................................................................................................................... 2
2.0 FIELD EXPLORATION ........................................................................................... 3
3.0 LABORATORY TESTING ....................................................................................... 3
3.1 Soil Classification ............................................................................................................ 3
3.2 Expansive Soil .................................................................................................................. 4
3.3 Compaction Tests ............................................................................................................. 4
3.4 Collapse Tests .................................................................................................................. 4
3.5 Chemical Tests ................................................................................................................. 4
4.0 FINDINGS ............................................................................................................... 5
4.1 Geologic Environment ..................................................................................................... 5
4.1.1 Regional Geologic Setting ........................................................................................ 5
4.1.2 Local Geologic Setting ............................................................................................. 5
4.1.3 Groundwater ............................................................................................................. 6
4.2 Faulting And Seismicity ................................................................................................... 6
4.2.1 Earthquake Characterization ..................................................................................... 6
4.2.2 Earthquake Intensity ................................................................................................. 6
4.2.3 2022 California Building Code (CBC) Seismic Design Criteria .............................. 7
4.3 Secondary Earthquake Effects ......................................................................................... 8
4.3.1 Ground Rupture ........................................................................................................ 8
4.3.2 Landsliding ............................................................................................................... 8
4.3.3 Liquefaction and Dry Sand Settlement Analysis ...................................................... 8
4.4 Hydro-Collapse ................................................................................................................ 9
5.0 CONCLUSIONS...................................................................................................... 9
6.0 RECOMMENDATIONS ........................................................................................... 9
6.1 Removals .......................................................................................................................... 9
6.2 Foundation Recommendations ....................................................................................... 10
6.2.1 Footings................................................................................................................... 10
6.2.2 Foundation General Recommendations .................................................................. 14
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6.3 Interior Slabs .................................................................................................................. 15
6.4 Exterior Slabs ................................................................................................................. 15
6.5 Corrosion Characteristics of Soil ................................................................................... 16
6.6 Preliminary Pavement Recommendations ..................................................................... 17
6.7 Grading ........................................................................................................................... 20
6.7.1 General .................................................................................................................... 20
6.7.2 Site Preparation ....................................................................................................... 21
6.7.3 Fill Placement ......................................................................................................... 22
6.7.4 Construction Considerations ................................................................................... 24
6.7.5 Temporary Excavation ............................................................................................ 25
6.7.6 Utility Trenching and Backfill ................................................................................ 26
7.0 CLOSURE ............................................................................................................ 28
Enclosures
References
Plate 1, Geologic Map
Appendix A, Field Exploration
Appendix B, Laboratory Test Results
cc: (1) Addressee
MDN 24446
6634 Valjean Avenue, Van Nuys, California 91406 Phone: (818) 785-2158 Fax: (818) 785-1548
October 29, 2024
W.O. 8003
1.0 INTRODUCTION
The purpose of this investigation is to determine the geologic and geotechnical conditions on
the site and their impact on proposed development, and to provide preliminary geologic and
geotechnical engineering data and recommendations to aid in budgeting and development of
the subject site. The following sections provide a summary of the geologic and geotechnical
engineering conditions on the site, and recommendations for site grading, fill placement, and
foundations.
This report has been prepared in accordance with generally accepted geotechnical
engineering practices in the City of Fontana at the time it was prepared. The report presents
a brief description of the site, the geotechnical engineering characteristics of the area, the
seismicity of the area, an engineering analysis of the site characteristics, conclusions, and
recommendations to develop the site.
Opinions presented in this report are based on an inspection of the site, geologic mapping, a
review of the regional geologic maps and seismic hazard reports, subsurface exploration and
laboratory testing, and our general knowledge of the geologic and soils engineering
conditions in the site area. The opinions presented have been arrived at through the exercise
of the generally understood standard of care for our profession and standard of engineering
practice for the City of Fontana, as we understand it. The environmental aspects of the site
were not within our scope of services.
1.1 Scope of Services
Our scope of services included the following:
• Site reconnaissance.
• Review of regional geologic maps, and seismic hazard reports.
• Excavating, sampling, and logging of three eight-inch diameter hollow stem auger
borings to a maximum depth of 50 feet below existing grades (Borings B-1 through
B-3). Boring logs are included in Appendix A.
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•Excavating, sampling, and logging of 7 backhoe test pits. Test pit logs are included
in Appendix A.
•Laboratory testing performed on samples retrieved from the borings (Appendix B).
•Preparation of this report.
Our scope of services did not include environmental soil testing.
1.2 Site Description
The subject site consists of 4.72 acres located at 7844 Citrus Avenue, Fontana (Figure
1). The site is generally level with existing residential development on the north, south,
and west sides of the property and Citrus Avenue along the east side. The site is
currently vacant.
1.3 Proposed Development
Proposed development will consist of the construction of 36, two-story single-family
residential structures with detached ADU’s. A recreation building and green area are
proposed in the central part of the site.
1.4 Limitations
The findings and recommendations of this report were prepared in accordance with
generally accepted professional geotechnical engineering principles and practice for
the City of Fontana at this time. We make no other warranty, either express or implied.
The conclusions and recommendations contained in this report are based on-site
conditions disclosed in our site exploration. However, soil/rock conditions can vary
significantly between borings; therefore, further refinements of our recommendations
contained herein may be necessary due to changes in the building plans or what is
encountered during site grading.
SITE LOCATION MAP
7844 CITRUS AVENUE
FONTANA, CALIFORNIA
RC HOMES
DATE:
W.O. NO.:
10/2024
GeoSoils Consultants Inc.
GEOTECHNICAL GEOLOGICGSC 8003 MD
N
2
4
4
4
6
FIGURE 1
SITE
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The recommendations provided in this report are applicable for preliminary
development planning for the referenced site provided that surface water will be kept
from infiltrating into the subgrade adjacent to the foundation systems. This may
include, but not be limited to rainwater, roof water, landscape water and/or leaky
plumbing. The lots are to be fine graded at the completion of construction to include
positive drainage away from the structure and roof water will be collected via gutters,
downspouts, and transported to the street in buried drainpipes. Home buyers should
be cautioned against constructing open draining planters adjacent to the houses or
obstructing the yard drainage in any way.
Since our investigation was based on the site conditions observed and engineering
analyses, the conclusions and recommendations contained herein are professional
opinions. Further, these opinions have been derived in accordance with standard
engineering practices, and no warranty is expressed or implied. Additional site
exploration, laboratory testing, and engineering analyses may be required once a final
site development plan is available.
2.0 FIELD EXPLORATION
GSC excavated, sampled, and logged three, eight-inch diameter hollow stem auger borings
(B-1 through B-3) and 7 backhoe test pits (TP-1 through TP-7) at the locations shown on
Plate 1. Boring and test pit logs are included in Appendix A.
3.0 LABORATORY TESTING
3.1 Soil Classification
Soil materials encountered in the borings were classified and described in accordance
with the Unified Soil Classification System and in general accordance with the current
version of Test Method ASTM D 2488. The assigned group symbols are presented in
the exploration logs, Appendix A.
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3.2 Expansive Soil
Expansion index testing was performed on selected bulk samples of the on-site soils
in accordance with the current version of Test Method ASTM D4829. The test results
of tests performed on the tract indicate a very low to low expansion index. Additional
testing will be performed at the completion of grading.
3.3 Compaction Tests
Compaction tests were performed on samples taken from the borings to determine the
moisture density relationships of the typical surficial soils encountered on the site. The
laboratory standard used was in accordance with ASTM Test Designation D-1557-12.
TABLE 1
COMPACTION TEST RESULTS
Sample Description
B-1 @ 5-10’ Brown slightly silty fine to coarse Sand
w/rock fragments 131.0 7.9
3.4 Collapse Tests
Four collapse tests were performed on selected ring samples taken from the borings
in Accordance with ASTM D-4546-21. The samples were inundated at an
approximate load of one ton per square foot to monitor the hydro-consolidation.
Loads were applied to the samples in several increments in geometric progression
and the resulting deformations were recorded at selected time intervals. Results of
the consolidation are presented on Plates CS-1 through CS-4 and indicate a low
potential for consolidation. Most of the noted collapse is considered to be due to
sample disturbances from very high blow counts required to obtain the samples.
3.5 Chemical Tests
Chemical testing for soil corrosiveness was performed by an outside laboratory and
the results are presented in Appendix B. The results of the testing are discussed in
Section 6.5 and additional testing will be completed at the end of grading.
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4.0 FINDINGS
4.1 Geologic Environment
Geologic conditions on the subject site were determined through research, field
mapping, and subsurface exploration, and the results were superimposed on the
Geologic Map, Plate 1. During grading, a geologist should be present to confirm the
geologic conditions encountered on the site are consistent with those presented
herein. The following sections present our findings concerning subsurface and
groundwater conditions.
4.1.1 Regional Geologic Setting
The subject site is located within the northern part of the Peninsular Ranges
Geomorphic Province of California. The Peninsular Ranges extend into lower
California and are bound on the east by the Colorado Desert. The Los Angeles
Basin and the island group (Santa Catalina, Santa Barbara, and the distinctly
terraced San Clemente and San Nicolas islands), together with the surrounding
continental shelf (cut by deep submarine fault troughs), are included in this
province. A series of ranges are separated by northwest trending valleys,
subparallel to faults branching from the San Andreas Fault. The trend of
topography is similar to the Coast Ranges, but the geology is more like the
Sierra Nevada, with granitic rock intruding the older metamorphic rock.
4.1.2 Local Geologic Setting
The subject site is located within an alluvial filled valley south of the San Gabriel
Mountains and north of the South San Jose Hills. Sediments filling the valley
were derived primarily from the San Gabriel Mountains.
Alluvium (Qal):
Alluvium underlies the site and consists of brown to yellowish brown, silty
gravelly sand and sandy gravel that is dry and dense. A high percentage of
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cobbles are present in the alluvium as noted on the test pit logs. Cobble range
from approximately 3 to 8 inches in diameter with some over 8 inches.
4.1.3 Groundwater
Groundwater was not encountered in the borings or test pits excavated on the
site to a maximum depth of 50 feet.
4.2 Faulting And Seismicity
The project site has not been evaluated by the California Geological Survey for the
potential for liquefaction. The site is not located within the Alquist-Priolo Earthquake
Fault Zone.
4.2.1 Earthquake Characterization
Earthquakes are characterized by magnitude, which is a quantitative measure
of the earthquake strength, based on strain energy released during a seismic
event. The magnitude of an earthquake is constant for any given site and is
independent of the site in question.
4.2.2 Earthquake Intensity
The intensity of an earthquake at a random site is not constant and is subject
to variations. The intensity is an indirect measurement of ground motion at a
particular site and is affected by the earthquake magnitude, the distance
between the site and the hypocenter (the location on the fault at depth where
the energy is released), and the geologic conditions between the site and the
hypocenter. Intensity, which is often measured by the Mercalli scale, generally
increases with increasing magnitude and decreases with increasing distance
from the hypocenter. Topography may also affect the intensity of an
earthquake from one site to another. Topographic effects such as steep sided
ridges or slopes may result in a higher intensity than sites located in relatively
flat-lying areas.
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4.2.3 2022 California Building Code (CBC) Seismic Design Criteria
The 2022 CBC (California Building Code) seismic coefficient criteria are
provided in Table 2 for structural design consideration. Under the Earthquake
Design Regulations of Chapter 16, Section 1613 of the CBC 2019, the following
coefficients apply for the proposed structures at the site. Site Class D should
be used for the site. The following seismic data is presented for preliminary
design purposes. Ground motion parameters based on the Mapped Risk-
Targeted Maximum Considered Earthquake (MCEr) were determined and
adhere to requirements discussed in ASCE 7-16 referenced by the 2022
California Building Code. The parameters include 5% critical damping for 0.2-
and 1.0-second time periods. A summary of parameters is provided in the table
below for a Site Class D designation. These values may only be used when
the value of the seismic response coefficient Cs satisfies equations 12.8-2,
12.8-3, or 12.8-4 of the ASCE 7-16 Standard.
TABLE 2
SEISMIC PARAMETERS
Description Value
Conformance to the above criteria for seismic excitation does not constitute
any kind of guarantee or assurance that significant structural damage or ground
failure will not occur if a maximum level earthquake occurs. The primary goal
of seismic design is to protect life and not to avoid all damage, since such
design may be economically prohibitive. Following a major earthquake, a
building may be damaged beyond repair, yet not collapse.
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4.3 Secondary Earthquake Effects
Ground shaking produced during an earthquake can result in a number of potentially
damaging phenomena classified as secondary earthquake effects. These secondary
effects include ground rupture, landslides, seiches and tsunamis, seismically induced
settlement, and liquefaction. Descriptions of each of these phenomena and how it
could potentially affect the proposed site are described as follows:
4.3.1 Ground Rupture
Ground rupture occurs when movement on a fault breaks the ground surface
and usually occurs along pre-existing fault traces where zones of weakness
already exist. The State has established Earthquake Fault Zones for the
purpose of mitigating the hazard of fault rupture by prohibiting the location of
most human occupancy structures across the traces of active faults.
Earthquake fault zones are regulatory zones that encompass surface traces of
active faults with a potential for future surface fault rupture.
The site is not located within a fault hazard zone and there are no known faults
on the site. Therefore, the potential for ground rupture is low.
4.3.2 Landsliding
Landslides are slope failures that occur where the horizontal seismic forces act
to induce soil and/or bedrock failures. The most common effect is reactivation
or movement on a pre-existing landslide. Typically, existing slides that are
stable under static conditions (i.e., factor-of-safety above one) become
unstable and move during strong ground shaking. The site is flat and not
subject to landslides.
4.3.3 Liquefaction and Dry Sand Settlement Analysis
Dry sand settlement can occur during moderate and large earthquakes when
loose, natural or fill sandy soils are densified and settled, often unevenly across
a site. In order for dry sand settlement to occur, the following four factors are
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required: 1) Relatively dry soil or soil situated above the groundwater table; 2)
undrained loading (strong ground shaking), such as by earthquake; 3)
contractive soil response during shear loading, which is often the case for a
soil which is initially in a loose or uncompacted state; and 4) susceptible soil
type; such as clean, uniformly graded sands. The site is not located within a
seismic hazard zone and is underlain by dense older alluvium deposits;
therefore, the potential for liquefaction and dry sand settlement is very low.
4.4 Hydro-Collapse
Hydro-collapse is a condition where dry or moist soils undergo settlement upon being
wetted. In many cases no additional surcharge load is necessary to trigger the hydro-
collapse. The potential for hydro-collapse has been evaluated based upon
observations, the results of Swell/Collapse or Consolidation tests, and moisture-
density determinations for samples taken from the field. The results of the testing
indicate a low potential for hydro-collapse of the alluvium following proposed removals.
5.0 CONCLUSIONS
The development of the subject site is considered feasible from a geologic and geotechnical
engineering viewpoint, provided that the recommendations presented in this report are
followed during grading. Once a grading plan is available, it should be forwarded to this office
for review and additional recommendations may be provided. The most critical factor
affecting the proposed development is the high percentage of cobbles in the alluvium.
6.0 RECOMMENDATIONS
6.1 Removals
Removals in areas of proposed grading shall extend into competent alluvium and shall
include removal of any existing fill, if found. Removals shall extend a minimum of five
feet below existing or proposed grades, whichever is deeper. Removals shall extend
a minimum of five feet beyond the building footprint. Deeper removals may be
required if soft or dry soil conditions are observed during grading. Preparation of areas
to receive fill and fill placement shall be performed as discussed under “Grading
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section”. Due to the dry nature of the upper soil zone, the bottom areas shall be
heavily watered following the recommended removals.
6.2 Foundation Recommendations
The following recommendations are provided for preliminary design purposes and the
final expansion index should be determined following grading. In our opinion,
conventional footings with slab-on-grade or post-tensioned slabs should be used to
support the proposed structures.
Foundations should be designed for low expansive soil conditions. The proposed
improvements should be founded into compacted fill. Under no circumstances should
foundations be cast atop loose, soft, or slough, debris, existing artificial fill, topsoil, or
surfaces covered by standing water. Prior to placing concrete in a foundation
excavation, an inspection should be made by our representative to ensure that the
foundation’s subgrade is free of loose and disturbed soils and is embedded in the
recommended material. We offer the following site-specific recommendations and
comments for purposes of foundation design and construction.
6.2.1 Footings
The proposed structures may be supported on footings bearing on compacted
fill with slab-on-ground or post-tensioned slabs. Exterior isolated pad footings
may need to be connected to adjacent footings via tie beams at the discretion
of the project structural engineer.
Subgrade Preparation
All conventional footings should be constructed on firm, unyielding certified
compacted fill. All compacted fills should be compacted to at least 90 percent
of the Modified Proctor maximum laboratory density, as determined by ASTM
D-1557-12 compaction method. Pre-moistening of all areas to receive
concrete is recommended. The moisture content of the subgrade soils should
be equal to or slightly greater than optimum moisture and verified by the
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Geotechnical Engineer to a depth of 12 inches below adjacent grade within 24
hours of concrete placement. Footing’s subgrades shall be prepared in
accordance with the Grading section of this report.
Bearing Capacity
Continuous footings should have a width of at least 15 and extend at least 18
inches below exterior grade.
Exterior isolated pad footings intended for support of roof overhangs such as
decks, patio covers, and similar construction should be a minimum of 24 inches
square and founded at a minimum depth of 18 inches below the lowest
adjacent final grade. Footings with at least above minimum dimensions may
be designed for a preliminary allowable bearing pressure of 1,500 pounds per
square foot (psf) for dead plus live loads, with a one-third increase allowed
when considering additional short-term wind or seismic loading. The allowable
bearing value may be increased by 300 pounds per square foot per foot
increase in depth or width to a maximum of 3000 psf. The weight of the footings
may be neglected for design purposes. All footings located adjacent to utility
lines should be embedded below a 1:1 plane extending up from the bottom
edge of the utility trench.
Settlement
The footings should be designed based on a low-expansive soils condition.
Thirty-year post-construction differential settlement due to static loads is not
expected to exceed about 0.25-inch over 30 feet span for the proposed
improvements supported on footings, provided that the foundations are
designed and constructed as recommended.
Lateral Capacity
Lateral loads may be resisted by friction between the bottom of the footings
and the supporting subgrade, and by passive soil pressure acting against the
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footings cast neat in foundation excavations or backfilled with properly
compacted structural fill. A coefficient of friction of 0.4 may be assumed for
design for footings supported on compacted fill. We recommend an equivalent
fluid pressure of 250 pounds per cubic foot for passive soil resistance and not
to exceed 2,500 pounds per square foot, where appropriate. When combining
passive pressure and frictional resistance, the passive pressure component
should be reduced by one-third.
General Structural Design
We recommend that foundations be reinforced with a minimum 2, No. 4 rebar
both top and bottom, to provide structural continuity and to permit spanning of
local irregularities.
Post-Tensioned Design
Post-tensioned slabs should be designed in accordance with the
recommendations of the Post-Tensioning Institute. Based on review of
laboratory data for the on-site materials, the on-site materials have a low
expansion index. Deepened footings/edges around the slab perimeter must
be used to minimize non-uniform surface moisture migration (from an outside
source) beneath the slab. An edge depth of at least 12 inches should be
considered. The bottom of the deepened footing/edge should be designed to
resist tension, using cable or reinforcement per the Structural Engineer.
Specific recommendations for Post Tension Institute methods are presented
below.
Post-tensioned slabs should be designed in accordance with the
recommendations of the Post-Tensioning Institute. Post-tensioned slabs
should have sufficient stiffness to resist excessive bending due to non-uniform
swell and shrinkage of subgrade soils. The differential movement can occur at
the corner, edge, or center of slab. The potential for differential uplift can be
evaluated using the design specifications of the Post-Tensioning Institute. The
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following table presents suggested minimum coefficients to be used in the
Post-Tensioning Institute design method.
TABLE 3
SUGGESTED PT COEFFICIENTS
Description Value
The coefficients are considered minimums and may not be adequate to
represent worst case conditions such as adverse drainage, excess watering,
and/or improper landscaping and maintenance. The above parameters are
applicable provided structures have gutters and downspouts, yard drains, and
positive drainage is maintained away from structure perimeters. Also, the
values may not be adequate if the soils below the foundation become saturated
or dry such that shrinkage occurs.
The parameters are provided with the expectation that subgrade soils below
the foundations are maintained in a relatively uniform moisture condition.
Responsible irrigation of landscaping adjacent to the foundation must be
practiced since over-irrigation of landscaping can cause problems. Therefore,
it is important that information regarding drainage, site maintenance,
settlements and effects of expansive soils be passed on to future homeowners.
Based on the above parameters, the following preliminary values were
obtained from the Post Tension Institute Design manual. If a stiffer slab is
desired, higher values of ym may be warranted.
TABLE 4
PRELIMINARY PT SLAB DESIGN VALUES
Description Value
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Underlayment
In areas where dampness of concrete floor slabs would be undesirable, such
as habitable building interiors, concrete slabs should be underlain by a
minimum 10 mil vapor barrier sandwiched between two (2) two-inch imported
sand layers. This vapor barrier shall be lapped and sealed (especially around
the utility perforations) adequately to provide a continuous waterproof barrier
under the entire slab. To reduce vapor transmission up through concrete slabs,
the vapor barrier should be high quality, UV-resistant conforming to the
requirements of ASTM E 1745 Class A, with a water vapor transmission rate
less than or equal to 0.01 perms (such as 15-mil thick “Stego Wrap Class A”).
The vapor barrier should be installed in accordance with ASTM E 1643. All
seams and penetrations of the vapor barrier should be sealed in accordance
with manufacturer’s recommendations.
6.2.2 Foundation General Recommendations
The above parameters are applicable provided structures have gutters and
downspouts and positive drainage is maintained away from structures.
Therefore, it is important that information regarding drainage and site
maintenance be passed on to future owners.
The above recommendations assume GeoSoils Consultants, Inc. strongly
recommends that surface water will be kept from infiltrating into the subgrade
adjacent to the building foundation system. This may include, but not be limited
to rainwater, roof water, landscape water and/or leaky plumbing. The lots are
to be fine graded at the completion of construction to include positive drainage
away from the structure and roof water will be collected via gutters,
downspouts, and transported to the street in buried drainpipes. Homebuyers
should be cautioned against constructing open draining planters adjacent to
the houses or obstructing the yard drainage in any way.
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• Utility trenches beneath the slabs should be backfilled with compacted
native soil materials, free of rocks.
• Standard City of Fontana structural setback guidelines are applicable,
except where superseded by specific recommendations by the Project
Geologist and Geotechnical Engineer.
• Building or structure footings shall be set back a horizontal distance, x, from
the face of adjacent descending slope. The horizontal distance is
calculated as x=H/3, where H is the height of slope. The distance x should
not be less than 5 feet nor more than 40 feet. The distance x may be
provided by deepening the footings.
• The ground immediately adjacent to the foundations shall be sloped away
from the building at a slope of not less (5%-slope) for a minimum distance
of 10’ measured perpendicular to the face of the wall. Impervious surfaces
within 10’ of the building foundation shall be sloped a minimum of 2% away
from the building.
6.3 Interior Slabs
Conventional Slab-on-ground Design
Conventional interior slabs should be at least 4 inches thick with No. 4 rebar at 16
inches on center. Moisture sensitive floors should be underlain by a minimum 10
vapor barrier as previously discussed in the Underlayment section.
6.4 Exterior Slabs
Subgrade Preparation
To reduce the potential for distress to exterior concrete flatwork, the subgrade soils
below concrete flatwork areas to a minimum depth of 12 inches should be moisture
conditioned to at least equal to, or slightly greater than, the optimum moisture content
and then compacted to a minimum relative compaction of 90 percent.
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Flooding or ponding of the subgrade is not considered feasible to achieve the above
moisture conditions since this method would likely require construction of numerous
earth berms to contain the water. Therefore, moisture conditioning should be
achieved with sprinklers or a light spray applied to the subgrade over a period of few
to several days just prior to pouring concrete. Pre-watering of the soils is intended to
promote uniform curing of the concrete, reduce the development of shrinkage cracks
and reduce the potential for differential expansion pressure on freshly poured flatwork.
A representative of the project geotechnical consultant should observe and verify the
density and moisture content of the soils, and the depth of moisture penetration prior
to pouring concrete.
Drainage
Drainage from patios and other flatwork areas should be directed to local area drains
and/or graded earth swales designed to carry runoff water to the adjacent streets or
other approved drainage structures. The concrete flatwork should be sloped at a
minimum gradient of one percent, or as prescribed by project civil engineer or local
codes, away from building foundations, retaining walls, masonry garden walls and
slope areas.
Thickened Edge
To improve performance, exterior slabs-on-grade may be constructed with a thickened
edge to improve edge stiffness and to reduce the potential for water seepage under
the edge of the slabs and into the underlying base and subgrade. In our opinion, the
thickened edges should be at least 8 inches wide and ideally should extend at least 8
inches below the bottom of the slab.
6.5 Corrosion Characteristics of Soil
As a screening level study, limited chemical and electrical tests were performed by an
outside laboratory on samples considered representative of the onsite soils to identify
potential corrosive characteristics of these soils. The common indicators that are
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MDN 24446
generally associated with soil corrosivity, among other indicators, include water-
soluble sulfate (a measure of soil corrosivity on concrete), water-soluble chloride (a
measure of soil corrosivity on metals embedded in concrete), pH (a measure of soil
acidity), and minimum electrical resistivity (a measure of corrosivity on metals
embedded in soils). Test methodology and results are presented in Appendix B.
It should be noted that GeoSoils does not practice corrosion engineering; therefore,
the test results, opinion and engineering judgment provided herein should be
considered as general guidelines only. Based on the test results, the on-site materials
have a negligible sulfate content and are not corrosive to ferrous metals. A corrosion
engineer should be consulted.
6.6 Preliminary Pavement Recommendations
Preliminary pavement recommendations are provided below. Additional R-Value
testing should be performed at the completion of grading to confirm the final sections.
Asphalt Concrete
Based on the laboratory test results, it is our opinion that an R-value of 78 is
appropriate for design of the parking area and drive isle pavements. Additional
subgrade samples will be obtained from the finished street subgrade to confirm these
results.
Using estimated Traffic Indices for various pavement loading conditions, we calculated
the minimum pavement section thicknesses presented in table below based on the
pavement design procedure described in Chapter 630 of the Caltrans Highway Design
Manual for design life of 20-year. We note that it is the civil engineer’s responsibility
to choose an appropriate traffic index for various pavement systems. Any local
jurisdiction minimum pavement sections should be followed. The minimum pavement
section per the City of Fontana for public streets is 4.5 inches of AC over 12 inches of
native soil subgrade compacted to 95 percent relative compaction with no base for
public streets. For private streets the minimum AC section should be 4 inches
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If the pavements are constructed in two stages, the following table provides the
minimum pavement section; however, the initial AC section should be 3 inches thick.
The final cap should be 1.5 inches of AC, for a total thickness of 4.5 inches. We note
that constructing pavements in two stages may pose some hazards for the overall
performance of pavement due to heavy construction equipment traffic on the relatively
thin initial layer.
TABLE 5
MINIMUM PAVEMENT SECTION THICKNESSES
Traffic Index Asphalt Thickness
(in)
Aggregate
Thickness (in) Compaction
5.5 4.5
(public streets) 0 Upper 12” compacted
to 95%
5.5 4.0
(private streets) 0 Upper 12” compacted
to 95%
5.5 3.0 Initial layer
1.5 final cap layer 3.0 Upper 12” compacted
to 95%
The Asphalt Concrete pavements may be underlain by approximately 3 feet of
compacted fill to a minimum relative compaction of 90 percent. Subgrade soils
immediately below the aggregate base, to a minimum depth of 12 inches, should be
compacted to a minimum relative compaction of 95 percent based on ASTM D1557.
Final subgrade compaction should be performed prior to placing base materials and
after utility-trench backfills have been compacted and tested.
Asphalt concrete and aggregate base should conform to and be placed in accordance
with the requirements of the Caltrans Standard Specifications, latest edition, except
that compaction of subgrades and aggregate base material should be based on ASTM
Test D1557. The base course should be compacted to 95 percent or more of the
maximum dry density as evaluated by ASTM D1557. The base materials should also
meet the specifications for Crushed Aggregate Base, Crushed Miscellaneous Base or
Processed Miscellaneous Base as defined in Section 200-2 of the current edition of
the Standard Specifications for Public Works Construction (Greenbook).
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AC Paving:
Prime coat may be omitted if all of the following conditions are met:
1. The asphalt pavement layer is placed within two weeks of completion of base
and/or subbase course.
2. Traffic is not routed over completed base before paving.
3. Construction is completed during the dry season of May through October.
4. The base is free of dirt and debris.
If construction is performed during the wet season of November through April, prime
coat may be omitted if no rain occurs between completion of base course and paving,
and the time between completion of base and paving is reduced to three days,
provided the base is free of dirt and debris. Where prime coat has been omitted and
rain occurs, traffic is routed over base course, or paving is delayed, measures shall
be taken to restore base course, subbase course, and subgrade to conditions that will
meet specifications as directed by the geotechnical engineer.
We recommend that measures be taken to limit the amount of surface water that seeps
into the aggregate base and subgrade below vehicle pavements, particularly where
the pavements are adjacent to landscape areas. Seepage of water into the pavement
base material can soften the subgrade, thereby increasing the amount of pavement
maintenance that is required and shortening the pavement service life. Deepened
curbs extending 4-inches below the bottom of the aggregate base layer are generally
effective in limiting excessive water seepage below the edges of pavement and into
the subgrade. Other types of water cutoff devices or edge drains may also be
considered to maintain pavement service life.
Rigid Concrete Pavements
If the driveway is constructed with Portland cement concrete (PCC), we recommend
the driveway pavement consist of at least 4 inches of PCC over 3 feet of fill compacted
to a minimum relative compaction of 90 percent. Subgrade soils immediately below
the PCC, to a minimum depth of 12 inches, should be compacted to a minimum
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MDN 24446
relative compaction of 95 percent based on ASTM D1557. Un-reinforced concrete for
the 4-inch-thick driveway pavement should have a 28-day compressive strength of at
least 3,500 psi. PCC pavements should be laterally constrained with curbs or
shoulders and sufficient control joints should be incorporated in the design and
construction to limit and control cracking.
The soil subgrade and aggregate base below the pavement section should be
prepared and compacted as recommended above. The use of a moisture cut-off or
thickened edge along the edges of the driveway would be desirable in order to reduce
water seepage below the edges of the driveway and into the underlying aggregate
base and subgrade, which can lead to premature pavement distress.
6.7 Grading
Grading of the site will consist of a cut/fill operation to create level pads, slopes, and
streets. The grading will involve the removing and recompacting of existing near
surface material, alluvium, and bedrock. We offer the following recommendations and
construction considerations concerning earthwork grading at the site.
6.7.1 General
Monitoring: We recommend that all earthwork (i.e., clearing, site preparation,
fill placement, etc.) should be conducted with engineering control under
observation and testing by the Geotechnical Engineer and in accordance with
the requirements within the Grading section of this report.
Job Site Safety: At all times, safety should have precedence over production
work. If an unsafe job condition is observed, it should be brought to the
attention of the grading contractor or the developer’s representative. Once this
condition is noted, it should be corrected as soon as possible, or work related
to the unsafe condition should be terminated.
The contractor for the project should realize that services provided by GSC do
not include supervision or direction of the actual work performed by the
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contractor, his employees, or agents. GSC will use accepted geotechnical
engineering and testing procedures; however, our testing and observations will
not relieve the contractor of his primary responsibility to produce a completed
project conforming to the project plans and specifications. Furthermore, our
firm will not be responsible for job or site safety on this project, as this is the
responsibility of the contractor.
6.7.2 Site Preparation
Existing Structure Location: The General Contractor should locate all surface
and subsurface structures on the site or on the approved grading plan prior to
preparing the ground.
Existing Structure Removal: Any underground structures (e.g., septic tanks,
wells, pipelines, foundations, utilities, etc.) that have not been located prior to
grading should be removed or treated in a manner recommended by the
Geotechnical Engineer.
Clearing and Stripping: The construction areas should be cleared and stripped
of all vegetation, trees, bushes, sod, topsoil, artificial fill, debris, asphalt,
concrete, and other deleterious material prior to fill placement.
Removals: Please refer to the Removals section of this report for specific
recommendations for removals.
Subgrade Preparation: We recommend that the subgrade for those areas
receiving any fill be prepared by scarifying the upper 12 inches and moisture
conditioning, as required to obtain at least optimum moisture, but not greater
than 120 percent of optimum. The scarified areas shall be compacted to at
least 90 percent of the maximum laboratory density, as determined by ASTM
D-1557-12 compaction method. All areas to receive fill should be observed by
the Geotechnical Engineer prior to fill placement.
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MDN 24446
Subgrade Verification and Compaction Testing: Regardless of material or
location, all fill material should be placed over properly compacted subgrades
or bedrock in accordance with this section. The condition of all subgrades shall
be verified by the Geotechnical Engineer before fill placement or earthwork
grading begins. Earthwork monitoring and field density testing shall be
performed during grading to provide a basis for opinions concerning the degree
of soil compaction attained. The Contractor should be responsible for notifying
the Geotechnical Engineer when such areas are ready for inspection.
Inspection of the subgrade may also be required by the controlling
governmental agency within the respective jurisdictions. Density tests should
also be done on the prepared subgrade to receive fill, unless the areas are
underlain by dense bedrock, as required by the Geotechnical Engineer.
6.7.3 Fill Placement
Laboratory Testing: Representative samples of materials to be utilized as
compacted fill should be analyzed in a laboratory to determine their physical
properties. If any material other than that previously tested is encountered
during grading, the appropriate analysis of this material should be conducted.
On-Site Fill Material: The on-site soils, in our opinion, are adequate for re-use
in controlled fills provided the soils do not contain any organic matter, debris,
and that over-sized rocks are buried in accordance with the recommendations
under Rock Fragments.
Rock Fragments: The alluvium on the site consists of abundant cobbles of
various sizes. Most cobbles are anticipated to be less than 12-inches in
diameter; however, larger cobbles and some boulders may be encountered in
deeper excavations. Any rock fragments over 6 inches should be kept a depth
of 3 feet below finished grades. Rocks greater than 6 inches in diameter should
be placed in accordance with the recommendations of the Geotechnical
Engineer. Rocks shall not be placed in concentrated pockets, shall be
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MDN 24446
surrounded with fine grained material, and the distribution of the rocks shall be
supervised by the Geotechnical Engineer. A sufficient amount of fine-grained
material shall be placed around the rocks to prevent nesting and to fill all void
space. An adequate amount of water will be required to force fines into any
open voids.
Fill Placement: Approved on-site material shall be evenly placed, watered,
processed, and compacted in controlled horizontal layers not exceeding eight
inches in loose thickness, and each layer should be thoroughly compacted with
approved equipment. The fill should be placed and compacted in horizontal
layers, unless otherwise recommended by the Geotechnical Engineer.
Compaction Criteria: For fills less than 40 feet in vertical thickness, each layer
shall be compacted to at least 90 percent of the maximum laboratory density
for material used as determined by ASTM D-1557-12. The field density shall
be determined by the ASTM D-1556-07 method or equivalent. Where moisture
content of the fill or density testing yields compaction results less than 90
percent, additional compaction effort and/or moisture conditioning, as
necessary, shall be performed, until the fill material is in accordance with the
requirements of the Geotechnical Engineer. For any fill over 40 feet in
thickness, the fill below a depth of 40 shall be compacted to 95 percent relative
compaction.
Fill Material - Moisture Content: All fill material placed must be moisture
conditioned, as required to obtain at least optimum moisture, but not greater
than 120 percent. If excessive moisture in the fill results in failing results or an
unacceptable “pumping” condition, then the fill should be allowed to dry until
the moisture content is within the necessary range to meet the required
compaction requirements or reworked until acceptable conditions are obtained.
Keying and Benching: All fills should be keyed and benched through all topsoil,
slopewash, alluvium or colluvium or creep material into firm material where the
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MDN 24446
slope receiving fill is steeper than 5:1 (Horizontal: Vertical) or as determined by
Geotechnical Engineer. The standard acceptable bench height is four feet into
suitable material. The key for side hill fills should be a minimum of 15 feet
within compacted fill or firm materials, with a minimum toe embankment of 2
feet into compacted fill, unless otherwise specified by the Geotechnical
Engineer.
Density Testing Intervals: In general, density tests should be conducted at
minimum intervals of 2 feet of fill height or every 500 to 1,000 cubic yards. Due
to the variability that can occur in fill placement and different fill material
characteristics, a higher number of density tests may be warranted to verify
that the required compaction is being achieved.
Grading Control: Earthwork monitoring and field density testing shall be
performed by the Geotechnical Engineer during grading to provide a basis for
opinions concerning the degree of soil compaction attained. The Contractor
should receive a copy of the Geotechnical Engineer's Daily Field Engineering
Report which will indicate the results of field density tests for that day. Where
failing tests occur or other field problems arise, the Contractor shall be notified
of such conditions by written communication from the Geotechnical Engineer
in the form of a conference memorandum, to avoid any misunderstanding
arising from oral communication.
Drainage Devices: Drainage devices should be constructed in compliance with
the ordinances of controlling governmental agencies, or with the
recommendations of the Geotechnical Engineer or Engineering Geologist.
6.7.4 Construction Considerations
Erosion Control: Erosion control measures, when necessary, should be
provided by the Contractor during grading and prior to the completion and
construction of permanent drainage controls.
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Compaction Equipment: It is also the Contractor's responsibility to have
suitable and sufficient compaction equipment on the project site to handle the
amount of fill being placed and the type of fill material to be compacted. If
necessary, excavation equipment should be shut down to permit completion of
compaction in accordance with the recommendations contained herein.
Sufficient watering devices/equipment should also be provided by the
Contractor to achieve optimum moisture content in the fill material.
Final Grading Considerations: Care should be taken by the Contractor during
final grading to preserve any berms, drainage terraces, interceptor swales, or
other devices of a permanent nature on or adjacent to the property.
6.7.5 Temporary Excavation
Where the necessary space is available, temporary unsurcharged
embankments may be sloped back without shoring. The slope should not be
cut steeper than the following gradient:
TABLE 6
TEMPORARY EXCAVATION SLOPE
Height Temporary Gradient
(Horizontal:Vertical)
In areas where soils with little or no binder are encountered, shoring or flatter
excavation slopes shall be made. These recommended temporary excavation
slopes do not preclude local ravelling or sloughing.
All applicable requirements of the California Construction and General Industry
Safety Orders, the Occupational Safety and Health Act, and the Construction
Safety Act should be met.
Where sloped embankments are used, the top of the slope should be
barricaded to prevent equipment and heavy storage loads within five feet of the
top of the slope. If the temporary construction embankments are to be
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MDN 24446
maintained for long periods, berms should be constructed along the top of the
slope to prevent runoff water from eroding the slope faces. The soils exposed
in the temporary backcut slopes during excavation should be observed by our
personnel so that modifications of the slopes can be made if variations in the
soil conditions occur. The temporary excavation slopes should be supported
within three weeks.
Grading of the site will consist of a cut/fill operation to create level pads, slopes,
and streets. The grading will involve the removing and recompacting of existing
near surface material and alluvium. We offer the following recommendations
and construction considerations concerning earthwork grading at the site.
6.7.6 Utility Trenching and Backfill
Utility Trenching: Open excavations and excavations that are shored shall
conform to all applicable Federal, State, and local regulations.
Backfill Placement: Approved on-site or imported fill material shall be evenly
placed, watered, processed, and compacted in controlled horizontal layers not
exceeding eight inches in loose thickness, and each layer should be thoroughly
compacted with approved equipment. All fill material should be moisture
conditioned, as required to obtain at least optimum moisture, but not greater
than 120 percent of optimum moisture content. The fill should be placed and
compacted on a horizontal plane, unless otherwise recommended by the
Geotechnical Engineer.
As an alternative to on-site or imported fill material, for shallow trenches where
pipe or utility lines may be damaged by mechanical compaction equipment,
such as under building floor slabs, imported clean sand having a sand
equivalent (SE) value of 30 or greater may be utilized. The sand backfill
materials should be watered to achieve near optimum moisture conditions and
then tamped into place. No specific relative compaction will be required;
however, observation, probing, and if deemed necessary, testing should be
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MDN 24446
performed by a representative of the project geotechnical consultant to verify
an adequate degree of compaction.
Backfill Compaction Criteria: Each layer of utility trench backfill shall be
compacted to at least 90 percent of the maximum laboratory density
determined by ASTM D-1557-12. The field density shall be determined by the
ASTM D-1556-07 method or equivalent. Where moisture content of the fill or
density testing yields compaction results less than 90 percent, additional
compaction effort and/or moisture conditioning, as necessary, shall be
performed, until the compaction criteria is reached.
Exterior Trenches Adjacent to Footings: Exterior trenches, paralleling a footing
and extending below a 1H:1V plane projected from the outside bottom edge of
the footing, should be compacted to 90 percent of the laboratory standard.
Sand backfill, unless it is similar to the in-place fill, should not be allowed in the
trench backfill areas. Density testing, along with probing, should be
accomplished to verify the desired results.
Pipe Bedding: We recommend that a minimum of 6 inches of bedding material
should be placed at the bottom of the utility trench. All bedding materials shall
extend at least 4 inches above the top of utilities which require protection during
subsequent trench backfilling. All trenches shall be wide enough to allow for
compaction around the haunches of the pipe.
Groundwater Migration: Backfilled utility trenches may act as French drains to
some extent, and considerable groundwater flow along utility bedding and
backfill should be expected. Wherever buried utilities, or structures which they
may intersect, could be adversely affected by such drainage, provisions shall
be made to collect groundwater migrating along the trench lines. These
situations include where buried utilities enter buildings, particularly where they
enter below grade mechanical rooms, and where buried utilities enter junction
boxes or switching stations that are intended to remain dry. Mitigation
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measures include, but are not limited to, placement of perforated drainpipes
below and continuous with bedding materials, and placement of seepage
barriers such as lean mix concrete or controlled density fill (CDF).
7.0 CLOSURE
We appreciate this opportunity to be of continued service to you. If you have any questions
regarding the content of this report or any other aspects of the project, please do not hesitate
to contact us.
MDN 24446
October 29, 2024
W.O. 8003
REFERENCES
California Division of Mines and Geology (CDMG), 1997, Guidelines for Evaluating and
Mitigating Seismic Hazards in California, Special Publication 117
California Department of Conservation, Division of Mines and Geology, 1997, Guidelines for
evaluating and mitigating seismic hazards in California: California Division of Mines and
Geology Special Publication 117, 74
GeoSoils Consultants Inc.
P-1
20'
TP-4
0-10' Qal
TP-1
0-15' Qal
TP-2
0-10' Qal
TP-3
0-10' Qal
TP-5
0-10' Qal
TP-6
0-10' Qal
TP-7
0-10' Qal
B-3
25'
B-2
50'
B-1
20'
WORK ORDER DATE SCALE
REVISED PLATE 1
6634 Valjean Avenue
Van Nuys, CA 91406GeoSoils Consultants Inc.
8003 10/2024 1" = 40'
GEOLOGIC MAP
7844 CITRUS AVENUE
FONTANA, CALIFORNIA
RC HOMES
GEOTECHNICAL GEOLOGICGSC
MD
N
2
4
4
4
6
EXPLANATION
APPROXIMATE LOCATION OF BORING
APPROXIMATE LOCATION OF TEST PIT
B-3
TP-7
Qal ALLUVIUM
APPROXIMATE LOCATION OF PERCOLATION TESTP-1
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MDN 24446
October 29, 2024
W.O. 8003
APPENDIX A
FIELD EXPLORATION
GeoSoils Consultants Inc.
PROJECT NAME W.O.
DRILLING COMPANY ABC Liovin DATE STARTED 9/6/2024 B-1
TYPE OF DRILL RIG Hollow Stem LOGGED BY RG SHEET 1 of 1
DRILLING METHOD HAMMER WT (lbs)
DIAMETER OF HOLE (IN)DROP (IN)
Boring Location:
De
p
t
h
(
f
t
)
Bl
o
w
s
/
1
2
"
(p
c
f
)
Ot
h
e
r
T
e
s
t
s
0
5 13/32/14 2.1 110.1
DRY, moderately firm
10 50 for 5 0.7 107.8
15 41/50 for 5 1.4 118.4
20 26/50 for 5 2.1 120.5
25
30
PLATE A-1
Standard Penetration Test
California Ring
Rock Core
GEOTECHNICAL BORING LOG
GEOTECHNICAL DESCRIPTION
0-20', ALLUVIUM (Qal)
5', Light brown to light yellowish brown, silty SAND with gravel, fine to coarse grained,
10', Light to medium brown, silty SAND with gravel, fine to coarse grained, dry,
firm
LEGEND
15', Medium brown, silty SAND with gravel and cobble, fine to coarse grained,
dry, moderately firm
No groundwater
TD=20'
coarse grained, dry, firm
20', Medium brown and grayish brown, SAND with gravel and cobble, fine to
SIEVE: Grain Size Analysis
#200: Washed Seive #200
MAX: Maximum Dry Density
DS: Direct Shear
C/S: Collapse/Swell
CONS: Consolidation
HYDR: Hydrometer Analysis
EXPAN: Expansion Index
CHEM: Chemical Tests
R-V: R-Value
PI: Atterberge Limits Tests
PROJECT NAME W.O.
DRILLING COMPANY ABC Liovin DATE STARTED 9/6/2024 B-2
TYPE OF DRILL RIG Hollow Stem LOGGED BY RG SHEET
DRILLING METHOD HAMMER WT (lbs)
DIAMETER OF HOLE (IN)DROP (IN)
Boring Location:
De
p
t
h
(
f
t
)
Bl
o
w
s
/
6
"
(p
c
f
)
Ot
h
e
r
T
e
s
t
s
0
5 12/7/7 0.9 112.5
to coarse grained, sligtly to moderately firm
10 24/26/46 2.0 123.3
15 18/37/50 for 5"3.6 107.1
20 24/50 for 5"
25 50 for 5"1.9
30
PLATE A-2
Standard Penetration Test
California Ring
Rock Core
GEOTECHNICAL BORING LOG
RC Homes 8003
GEOTECHNICAL DESCRIPTION
0-25', ALLUVIUM (Qal)
10', Light brown to medium reddish brown, silty SAND with gravel, fine to
coarse grained,slightly moist, dry, moderately firm
15', Dark brown with gray, silty SAND with gravel, fine to coarse grained, slightly
moist, fine to coarse grained, moderately firm
20', No Recovery
25, Dark brown gray, silty SAND, fine to coarse grained, slightly moist, with gravel,
firm
TD=20'
No groundwater
LEGEND SIEVE: Grain Size Analysis
#200: Washed Seive #200
MAX: Maximum Dry Density
DS: Direct Shear
C/S: Collapse/Swell
CONS: Consolidation
HYDR: Hydrometer Analysis
EXPAN: Expansion Index
CHEM: Chemical Tests
R-V: R-Value
PI: Atterberge Limits Tests
PROJECT NAME W.O.
DRILLING COMPANY ABC Liovin DATE STARTED 9/6/2024 B-3
TYPE OF DRILL RIG Hollow Stem LOGGED BY RG SHEET
DRILLING METHOD HAMMER WT (lbs)
DIAMETER OF HOLE (IN)DROP (IN)
Boring Location:
De
p
t
h
(
f
t
)
Bl
o
w
s
/
6
"
(p
c
f
)
Ot
h
e
r
T
e
s
t
s
0
5 9/26/24
to coarse grained, dry, moderately firm
10 29/24/36 3.4 128.2
15 9/15 for 5"0.8 108.1
20 26/50 for 5"
25 17/50 for 4"
30
PLATE A-3
Standard Penetration Test
California Ring
Rock Core
LEGEND SIEVE: Grain Size Analysis
#200: Washed Seive #200
MAX: Maximum Dry Density
DS: Direct Shear
C/S: Collapse/Swell
CONS: Consolidation
HYDR: Hydrometer Analysis
EXPAN: Expansion Index
CHEM: Chemical Tests
R-V: R-Value
PI: Atterberge Limits Tests
30', No recovery
20', Dark brown to gray, silty SAND with gravel, fine to coarse grained, dry,
moderately firm
25, Dark brown gray, silty SAND with gravel, fine to coarse grained, dry,
moderately firm
10', Light brown to light grayish brown, silty SAND with gravel and cobble, fine to
coarse grained, dry, moderately firm
15', Light brown to medium brown, SAND with gravel, fine to coarse grained, slightly
moist, moderately firm
5', Light brown to light grayish brown, silty SAND with gravel and cobble, fine
GEOTECHNICAL BORING LOG
RC Homes 8003
BORING NO.
GROUND ELEV.
GW ELEV.
Sa
m
p
l
e
T
y
p
e
GEOTECHNICAL DESCRIPTION
0-50', ALLUVIUM (Qal)
PROJECT NAME W.O.
DRILLING COMPANY ABC Liovin DATE STARTED 9/6/2024 B-3
TYPE OF DRILL RIG Hollow Stem LOGGED BY RG SHEET
DRILLING METHOD HAMMER WT (lbs)
DIAMETER OF HOLE (IN)DROP (IN)
Boring Location:
De
p
t
h
(
f
t
)
Bl
o
w
s
/
6
"
(p
c
f
)
Ot
h
e
r
T
e
s
t
s
35 50 for 4"5.9 118.4
40 39/40/44
45 41/22/50 for 3"
50 50 for 5"
55
60
65
PLATE A-4
Standard Penetration Test
California Ring
Rock Core
GEOTECHNICAL BORING LOG
RC Homes 8003
GEOTECHNICAL DESCRIPTION
35', Dark brown, silty SAND fine to coarse grained, slightly moist, firm
No groundwater
45', Dark brown, silty SAND with gravel, slightly moist, fine to coarse grained, firm
50', Dark brown with gray, silty SAND with gravel, fine to coarse grained, slightly
moist, firm
TD=50'
LEGEND SIEVE: Grain Size Analysis
#200: Washed Seive #200
MAX: Maximum Dry Density
DS: Direct Shear
C/S: Collapse/Swell
CONS: Consolidation
HYDR: Hydrometer Analysis
EXPAN: Expansion Index
CHEM: Chemical Tests
R-V: R-Value
PI: Atterberge Limits Tests
PROJECT NAME W.O.
DRILLING COMPANY ABC Liovin DATE STARTED 9/6/2024 P-1
TYPE OF DRILL RIG Hollow Stem LOGGED BY RG SHEET
DRILLING METHOD HAMMER WT (lbs)
DIAMETER OF HOLE (IN)DROP (IN)
Boring Location:
De
p
t
h
(
f
t
)
Bl
o
w
s
/
6
"
(p
c
f
)
Ot
h
e
r
T
e
s
t
s
0
coarse grained, slightly moist, moderately firm
5
10
15
20
25
30
PLATE A-5
Standard Penetration Test
California Ring
Rock Core
GEOTECHNICAL BORING LOG
RC Homes 8003
GEOTECHNICAL DESCRIPTION
0-20', ALLUVIUM (Qal)
Light brown to light yellowish brown, silty SAND with pebbles and gravel, fine to
13', Layer of large gravel/cobble
15', Changed to a medium to darkish brown, silty SAND with gravel and pebbles,
fine to coarse grained, slightly moist, moderately firm to firm
TD=20'
No GW
LEGEND SIEVE: Grain Size Analysis
#200: Washed Seive #200
MAX: Maximum Dry Density
DS: Direct Shear
C/S: Collapse/Swell
CONS: Consolidation
HYDR: Hydrometer Analysis
EXPAN: Expansion Index
CHEM: Chemical Tests
R-V: R-Value
PI: Atterberge Limits Tests
Qal
Qal
Qal
Qal
Qal
Qal
Qal
MDN 24446
October 29, 2024
W.O. 8003
APPENDIX B
LABORATORY TEST RESULTS
GeoSoils Consultants Inc.
Cleint:
Work Order:
Test Date:
Sample:
Soil Classification:
Test Procudure:
Lab and QC By:
Final Moisture Content (%)14.60 -2.4
Init. Dry Density (PCF)128.2 0.0
Init. Void Ratio 0.39
ASTM D 4546-21
RA
Plate: CS-1COLLAPSE/SWELL TEST DIAGRAM
Swell (%):
Hydroconsolidation (%) :
RC Homes
8003
10/22/2024
B-3 @ 10.0'
Gray brown slightly silty very fine to coarse SAND.
-20
-18
-16
-14
-12
-10
-8
-6
-4
-2
0
2
4
0.01 0.1 1 10 100Normal Pressure (tsf)
Deformation-Normal Pressure Curve
De
f
o
r
m
a
t
i
o
n
(
%
)
Water Added @ 1.0 tsf
Cleint:
Work Order:
Test Date:
Sample:
Soil Classification:
Test Procudure:
Lab and QC By:
Final Moisture Content (%)14.87 -2.7
Init. Dry Density (PCF)108.1 0.0
Init. Void Ratio 0.39
RC Homes
8003
10/22/2024
B-3 @ 15.0'
Gray brown very fine to coarse SAND.
Plate: CS-2COLLAPSE/SWELL TEST DIAGRAM
Swell (%):
Hydroconsolidation (%) :
ASTM D 4546-21
RA
-20
-18
-16
-14
-12
-10
-8
-6
-4
-2
0
2
4
0.01 0.1 1 10 100Normal Pressure (tsf)
Deformation-Normal Pressure Curve
De
f
o
r
m
a
t
i
o
n
(
%
)
Water Added @ 1.0 tsf
Cleint:
Work Order:
Test Date:
Sample:
Soil Classification:
Final Moisture Content (%)14.35 -1.5
Init. Dry Density (PCF)112.5 0.0
Init. Void Ratio 0.38
RC Homes
8003
10/24/2024
B-2 @ 5.0'
Light brown slightly silty very fine to coarse SAND with rock fragments.
Plate: CS-3COLLAPSE/SWELL TEST DIAGRAM
Swell (%):
Hydroconsolidation (%) :
-20
-18
-16
-14
-12
-10
-8
-6
-4
-2
0
2
4
0.01 0.1 1 10 100Normal Pressure (tsf)
Deformation-Normal Pressure Curve
De
f
o
r
m
a
t
i
o
n
(
%
)
Water Added @ 1.0 tsf
Cleint:
Work Order:
Test Date:
Sample:
Soil Classification:
Test Procudure:
Lab and QC By:
Final Moisture Content (%)15.11 -0.7
Init. Dry Density (PCF)123.3 0.0
Init. Void Ratio 0.39
RC Homes
8003
10/24/2024
B-2 @ 10.0'
Brown very fine to coarse SAND.
Plate: CS-4COLLAPSE/SWELL TEST DIAGRAM
Swell (%):
Hydroconsolidation (%) :
ASTM D 4546-21
RA
-20
-18
-16
-14
-12
-10
-8
-6
-4
-2
0
2
4
0.01 0.1 1 10 100Normal Pressure (tsf)
Deformation-Normal Pressure Curve
De
f
o
r
m
a
t
i
o
n
(
%
)
Water Added @ 1.0 tsf
Sample ID B-1
@ 5.0-10.0'
Resistivity Units
as-received ohm-cm 720,000
minimum ohm-cm 28,800
pH 7.3
Electrical Conductivity mS/cm 0.03
Chemical Analyses
Cations
calcium
magnesium
sodium
potassium
ammonium
Anions
carbonate
bicarbonate
fluoride
chloride
sulfate
nitrate
phosphate
Other Tests
% moisture 2
total acidity 1+mmol/kg na
sulfide
Redox mV na
Minimum resistivity and pH per CTM 643, Chloride per CTM 422, Sulfate per CTM 417
Electrical conductivity in millisiemens/cm and chemical analyses were made on a 1:5 soil-to-water extract.
mg/kg = milligrams per kilogram (parts per million) of dry soil.
Redox = oxidation-reduction potential in millivolts
ND = not detected
na = not analyzed
Table 1 - Laboratory Tests on Soil Samples
RC Homes
Your #8003, HDR Lab #24-0453LAB
25-Sep-24
GeoSoils Consultants, Inc.
431 West Baseline Road ∙ Claremont, CA 91711
Page 2 of 2
Client:
Work Order:
Test Date:
Sample:
Soil Classification:
Compaction Procedure:
Lab and QC by:
131.0 / rock correction: 135.5
OPTIMUM MOISTURE CONTENT (%):8.5 / rock correction: 7.9
A Mold diameter (in)4 4 4 4 4
B Mold height (in)4.581 4.581 4.581 4.581 4.581
C Wt. of Mold (g)4276 4276 4276 4276 4276
D Moist Soil + Mold (g)6395 6439 6455 0 0
E Soil Wt. (g)2119 2163 2179 -4276 -4276
F Volume of mold (ft3)0.0334 0.0334 0.0334 0.0334 0.0334
944.99 944.99 944.99 944.99 944.99
2.24235 2.2889131 2.305844506 -4.524916 -4.52492
M Wt. of wet soil (g)200 200 200 200 200
N Wt. of dry soiltare (g)186.5 183.2 180.1 176.1 175
13.5 16.8 19.9 23.9 25
7.2 9.2 11.0 #N/A #N/A
2.1 2.1 2.1 #N/A #N/A
130.5 130.9 129.6 #N/A #N/A
RC Homes
ASTM D 1557 Method A
Brown slightly silty very fine to coarse SAND with rock fragments.
B-1 @ 5.0'-10.0'
9/17/2024
8003
MAXIMUM DRY DENSITY:
Plate: MDD-1
RA
90.0
95.0
100.0
105.0
110.0
115.0
120.0
125.0
130.0
135.0
140.0
0.1 1.0 10 11
Gs=2.7 Gs=2.8
Gs=2.9
MOISTURE CONTENT (%)
DR
Y
D
E
N
S
I
T
Y
(
p
c
f
)
GeoSoils Consultants Inc.
MD8003.1.xls
CLIENT :RC Homes WORK
ORDER NO :8003 DATE :10/22/24
SAMPLE DENSITY MOISTURE %DENSITY RELATIVE
COMPACTION NOTES
B-1 @ 5.0 112.5 2.1 110.1
B-1 @ 10.0 108.5 0.7 107.8
B-1 @ 15.0 120.1 1.4 118.4
B-1 @ 20.0 123.1 2.1 120.5
B-2 @ 10.0 132.5 3.4 128.2
B-2 @ 15.0 108.9 0.8 108.1
B-3 @ 5.0 113.5 0.9 112.5
B-3 @ 10.0 125.8 2.0 123.3
B-3 @ 15.0 111.0 3.6 107.1
B-3 @ 20.0 128.0 2.5 125.0
B-3 @ 25.0 -1.9 -Disturbed.
B-3 @ 35.0 125.4 5.9 118.4
RELATIVE COMPACTION DETERMINATION
WORKSHEET
"R" VALUE CA 301
Client: GeoSoils Consultants, Inc.ATL No.:C 8276 Date:10/4/2024
Client Reference No.: 8003
Sample: B-1 @ 5-10'Soil Type:Brown, Silty Sand w. Gravel
TEST SPECIMEN A B C D
Compactor Air Pressure psi 350 350 350
Initial Moisture Content %8.6 8.6 8.6
Moisture at Compaction %8.6 8.1 8.3
Briquette Height in.2.50 2.48 2.48
Dry Density pcf 135.1 133.7 134.4
EXUDATION PRESSURE psi 123 438 245
EXPANSION PRESSURE psf 0 0 0
Ph at 1000 pounds psi 16 12 14
Ph at 2000 pounds psi 29 19 24
Displacement turns 4.25 4.48 4.32
"R" Value 73 81 77
CORRECTED "R" VALUE 73 81 77
Final "R" Value
BY EXUDATION:78
@ 300 psi
BY EXPANSION:N/A
TI = 5.0
5
0
10
20
30
40
50
60
70
80
90
0 100 200 300 400 500 600 700 800
"R
"
V
a
l
u
e
Exudation Pressure