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ALTA CALIFORNIA GEOTECHNICAL, INC.
LINFIELD CHRISTIAN SCHOOL November 15, 2023
31950 Pauba Road Project No. 1‐0502
Temecula CA, 92592
Attention: Mr. Marc Horton
Subject: GEOTECHNICAL INVESTIGATION REPORT
31950 Pauba Road,
City of Temecula, County of Riverside, California
References: Alta California Geotechnical, Inc., 2016, Geotechnical Update Report and Review
of Conceptual Grading Plans Linfield Village, APN 955‐020‐006 City of Temecula,
California, dated August 31, 2016 by Alta California Geotechnical, Inc. (Project
Number 1‐0155A).
Alta California Geotechnical, Inc., 2015, Geotechnical Investigation, Linfield
Property, Tract 36098‐1, Parcels 1 through 3, and Tract 3698‐2, Parcel 1, City of
Temecula, California, dated June 15, 2015 by Alta California Geotechnical, Inc.
(Project Number 1‐0155A).
Dear Mr. Horton:
Presented herein is Alta California Geotechnical, Inc.’s (Alta) geotechnical report for the
improvements to be constructed at the Linfield Christian School, located at 31950 Pauba Road,
west of the City of Temecula, Riverside County, California. This report is based on Alta’s recent
subsurface investigation, laboratory testing, a review of the 1‐inch equals 40 feet scale
Preliminary Conceptual Grading Plan, prepared by KWC Engineers, Alta’s previous site
investigations, published geologic maps, and Alta’s staff’s experience with similar projects in
this vicinity.
Alta’s review of the geotechnical data and the conceptual grading plan indicates that the
proposed development is feasible, from a geotechnical perspective, provided that the
recommendations presented in this report are incorporated into the grading and improvement
plans and implemented during site development.
APPROVED BY
CITY OF TEMECULA
PUBLIC WORKS
david.pina 03/12/2024
03/12/2024 03/12/2024
03/12/20
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ALTA CALIFORNIA GEOTECHNICAL, INC.
Included in this report are:
Discussion of the site geotechnical conditions.
Recommendations for remedial and site grading, including unsuitable soil removals.
Geotechnical site construction recommendations.
Preliminary foundation design parameters.
If you have any questions or should you require any additional information, please contact the
undersigned at (951) 509‐7090. Alta appreciates the opportunity to provide geotechnical
consulting services for your project.
Sincerely,
Alta California Geotechnical, Inc.
________________________________
YOUSSEF F. HIJAZI
Engineering Geology Associate
___________________________________
SCOTT A. GRAY/RGE 2857
Reg. Exp.: 12‐31‐24
Registered Geotechnical Engineer
President
___________________________________
THOMAS J. MCCARTHY/CEG 2080
Reg. Exp.: 9‐30‐24
Certified Engineering Geologist
Vice President
Distribution: (1) Addressee
YFH:SAG:TJM 1‐0502 November 15 2023 (Linfield Christian School (Geotechnical Investigation Report Linfield, Temecula CA)
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ALTA CALIFORNIA GEOTECHNICAL, INC.
1.0 INTRODUCTION ...............................................................................................................1
1.1 Purpose .....................................................................................................................1
1.2 Scope of Work .........................................................................................................1
1.3 Report Limitations ...................................................................................................2
2.0 PROJECT DESCRIPTION ..................................................................................................2
2.1 Site Location and Existing Conditions ....................................................................2
2.2 Proposed Development ............................................................................................2
3.0 SITE INVESTIGATION .....................................................................................................3
3.1 Current Subsurface Investigation .............................................................................3
3.2 Previous Subsurface Investigation ...........................................................................3
4.0 GEOLOGIC CONDITIONS ................................................................................................3
4.1 Geologic and Geomorphic Setting ...........................................................................3
4.2 Stratigraphy ..............................................................................................................4
4.2.1 Topsoil (no map symbol) .............................................................................4
4.2.2 Alluvium (Map symbol Qal) ........................................................................4
4.2.3 Pauba Formation (Map symbol Qp) ............................................................4
4.3 Geologic Structure ...................................................................................................5
4.3.1 Tectonic Framework ....................................................................................5
4.3.2 Regionally Mapped Active Faults ...............................................................5
4.3.3 Geologic Structure .......................................................................................5
4.4 Groundwater ............................................................................................................6
4.5 Earthquake Hazards .................................................................................................6
4.5.1 Local and Regional Faulting ........................................................................6
4.5.2 Seismicity .....................................................................................................6
4.5.3 Surface Rupture ...........................................................................................7
4.5.4 Liquefaction .................................................................................................7
4.5.5 Dry Sand Settlement ....................................................................................7
4.6 Regional Subsidence ................................................................................................8
5.0 ENGINEERING PROPERTIES AND ANALYSIS ...........................................................8
5.1 Materials Properties .................................................................................................8
5.1.1 Excavation Characteristics ...........................................................................8
5.1.2 Compressibility ............................................................................................8
5.1.3 Hydro-Consolidation....................................................................................8
5.1.4 Expansion Potential .....................................................................................9
5.1.5 Earthwork Adjustments ...............................................................................9
5.1.6 Chemical Analyses.....................................................................................10
5.2 Engineering Analysis .............................................................................................10
5.2.1 Bearing Capacity and Lateral Earth Pressures ...........................................10
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6.0 CONCLUSIONS AND RECOMMENDATIONS ............................................................11
6.1 Remedial Grading Recommendations ...................................................................11
6.1.1 Site Preparation ..........................................................................................11
6.1.2 Unsuitable Soil Removals ..........................................................................11
6.1.2.1 Future Maintenance Building .............................................................................. 12
6.1.2.2 Parking Lot .......................................................................................................... 12
6.1.3 Over-Excavation of Building Pads ............................................................13
6.1.3.1 Cut/Fill Transition Pads ...................................................................................... 13
6.1.3.2 Cut Pads............................................................................................................... 13
6.2 General Earthwork Recommendations ..................................................................14
6.2.1 Compaction Standards ...............................................................................14
6.2.2 Groundwater/Seepage ................................................................................14
6.2.3 Documentation of Removals ......................................................................14
6.2.4 Treatment of Removal Bottoms .................................................................15
6.2.5 Fill Placement ............................................................................................15
6.2.6 Moisture Content .......................................................................................15
6.2.7 Mixing ........................................................................................................15
6.2.8 Import Soils ................................................................................................15
6.2.9 Utility Trenches .........................................................................................16
6.2.9.1 Excavation ........................................................................................................... 16
6.2.9.2 Backfill ................................................................................................................ 16
6.2.10 Fill Slope Construction ..............................................................................17
6.2.11 Backcut Stability ........................................................................................18
7.0 DESIGN CONSIDERATIONS .........................................................................................18
7.1 Structural Design ...................................................................................................18
7.2 Moisture Barrier .....................................................................................................19
7.3 Seismic Design.......................................................................................................20
7.4 Block Walls ............................................................................................................21
7.5 Footing Excavations ...............................................................................................21
7.6 Exterior Slabs and Walkways ................................................................................21
7.6.1 Subgrade Compaction ................................................................................21
7.6.2 Subgrade Moisture .....................................................................................21
7.6.3 Concrete Slab Thickness ............................................................................21
7.6.4 Concrete Slab Reinforcement ....................................................................22
7.6.5 Control Joints .............................................................................................22
7.7 Concrete Design .....................................................................................................22
7.8 Corrosion................................................................................................................22
7.9 Pavement Design ...................................................................................................23
7.10 Site Drainage ..........................................................................................................24
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7.11 Deepened Footings and Setbacks...........................................................................24
8.0 LOT MAINTENANCE .....................................................................................................25
8.1 Lot Drainage ..........................................................................................................25
8.2 Burrowing Animals ................................................................................................26
9.0 FUTURE PLAN REVIEWS ..............................................................................................26
10.0 CLOSURE .........................................................................................................................26
10.1 Geotechnical Review .............................................................................................26
10.2 Limitations .............................................................................................................27
APPENDIX A: REFERENCES
APPENDIX B: SUBSURFACE INVESTIGATION
APPENDIX B‐1: PREVIOUS SUBSURFACE INVESTIGATION
APPENDIX C: LABORATORY TESTING
APPENDIX D: EARTHWORK SPECIFICATIONS
APPENDIX E: GRADING DETAILS
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ALTA CALIFORNIA GEOTECHNICAL, INC.
1.0 INTRODUCTION
The following report presents Alta’s findings, conclusions, and geotechnical
recommendations for the proposed development of Linfield Christian School, located at
31950 Pauba Road, west of the City of Temecula, in Riverside County, California.
1.1 Purpose
The purpose of this report is to examine the existing onsite geotechnical
conditions and assess the impacts that the geotechnical conditions may have on
the proposed development as depicted on the accompanying conceptual grading
plan. This report is suitable for submittal to the governing agencies and
engineer’s cost estimates.
1.2 Scope of Work
Alta’s Scope of Work for this geotechnical investigation included the following:
Review of the referenced literature, maps, reports and aerial photos
(Appendix A).
Site geologic mapping.
Excavating, logging, and sampling five (5) hollow‐stem auger borings to a
maximum depth of 26.0 feet below existing grade (Appendix B).
Compiling previous subsurface and laboratory data from the referenced
reports (Appendix B‐1).
Conducting laboratory testing on samples obtained during our
investigation (Appendix C).
Evaluating engineering geologic and geotechnical engineering data,
including laboratory data, to develop recommendations for site remedial
grading, import soil, foundations and utilities.
Preparing this report and accompanying exhibits.
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1.3 Report Limitations
The conclusions and recommendations presented in this report are based on the
field and laboratory information generated during previous investigations and
our current investigation, and a review of the referenced reports. The
information contained in this report is intended to be used for submittal to
appropriate governing agencies and engineers cost estimates.
2.0 PROJECT DESCRIPTION
2.1 Site Location and Existing Conditions
The irregular‐shaped, approximately 3.4‐acre site is bounded to the north by
Rancho Vista Road, to the south by Linfield Way, and to the east and west by
private properties. The site is currently being used as a parking lot for Linfield
Christian School.
Elevations range from approximately 1230 feet above sea level (ASL) near the
northeast corner of the site to approximately 1210 feet (ASL) in the southwest
corner of the site providing 20 feet of relief. Review of vintage air photos
(Historic Aerials, 2023) indicates that the site was vacant until 1978 when Linfield
Christian School and the development near the northeast corner had been
constructed. By 2005, Linfield Way had been developed. By 2020, the most
recent vintage air photo, the development in the northeast corner still remained,
but during Alta’s subsurface investigation it was found the development has
since been removed.
2.2 Proposed Development
It is our understanding that the site will be developed to support an additional
parking lot and the expansion of the existing maintenance yard. Alta anticipates
the conventional cut‐and fill‐grading techniques will be used to develop the site.
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3.0 SITE INVESTIGATION
3.1 Current Subsurface Investigation
Alta conducted subsurface investigation on October 19th of 2023 consisting of
the excavating, logging, and sampling of five (5) hollow stem auger borings to a
maximum depth of 26.0 feet below existing grade. The locations of the
exploratory excavations are shown on Plate 1 and the boring logs are presented
in Appendix B.
Laboratory testing was performed on bulk and ring samples obtained during the
field investigation. A brief description of the laboratory test procedures and the
test results are presented in Appendix C.
3.2 Previous Subsurface Investigation
Alta conducted a subsurface investigation for the overall Linfield site in May of
2015, which consisted of excavating, logging, and sampling of four (4) bucket
auger borings (B‐1 through B‐4) and eleven (11) backhoe test pits (T‐10 through
T‐17, T‐19, T‐25, and T‐26). The locations of the excavations that are within the
limits of this report are shown on Plate 1 and the logs are shown in Appendix B‐
1.
Alta also conducted two (2) preliminary infiltration tests, one within the limits of
this report as shown in Plate 1, in geologic units considered representative of the
Linfield Property.
4.0 GEOLOGIC CONDITIONS
4.1 Geologic and Geomorphic Setting
Regionally, the subject site is located in the Peninsular Ranges geomorphic
province, which characterizes the southwest portion of southern California
where major right‐lateral active fault zones predominately trend northwest‐
southeast. The Peninsular Ranges province is composed of plutonic and
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metamorphic rock, with lesser amounts of Tertiary volcanic and sedimentary
rock, Quaternary drainage in‐fills and sedimentary veneers.
4.2 Stratigraphy
Based on Alta’s review of the geologic literature, and our subsurface
investigation, the project site is underlain by the Pauba formation. The Pauba
formation consists of Pleistocene‐age older alluvium. This geologic unit is briefly
described below.
4.2.1 Topsoil (no map symbol)
Relatively thin topsoil covers portions of the site. It consists
predominantly of brown silty sand. The topsoil is dry to slightly moist,
and medium dense. The average thickness of the topsoil is approximately
one (1) foot.
4.2.2 Alluvium (Map symbol Qal)
Holocene‐aged alluvium was encountered in limited areas throughout
the site, usually within and adjacent to drainages. The alluvium within
the site is estimated to be about two and a half (2.5) feet deep. The
alluvium overlies the Pauba Formation. The alluvium generally consists of
brown, medium grained silty sand, dry, and loose condition.
4.2.3 Pauba Formation (Map symbol Qp)
The late‐to‐middle Pleistocene‐age Pauba Formation consists of reddish
brown, brown, greenish brown, tan and gray sandy clay, clayey sand,
clay, clayey silt, silty clay, silty sand, and sand. The materials encountered
were dry to moist, and in a firm/medium dense to very dense condition.
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4.3 Geologic Structure
4.3.1 Tectonic Framework
Jennings (1985) defined eight structural provinces within California that
have been classified by predominant regional fault trends and similar fold
structure. These provinces are in turn divided into blocks and sub‐blocks
that are defined by “major Quaternary faults.” These blocks and sub‐
blocks exhibit similar structural features. Within this framework the site
is located within Structural Province I, which is controlled by the
dominant northwest trend of the San Andreas Fault and is divided into
two blocks, the Coast Range Block and the Peninsular Range Block. The
Peninsular Range Block, on which the site is located, is characterized by a
series of parallel, northwest trending faults that exhibit right lateral dip‐
slip movement. These faults are terminated by the Transverse Range
block to the north and extend southward to the Baja Peninsula. These
northwest trending faults divide the Peninsular Range block into eight
sub‐blocks. The site is located on the Riverside sub‐block, which is bound
on the west by the Elsinore‐Whittier fault zone and on the east by San
Jacinto fault zone.
4.3.2 Regionally Mapped Active Faults
Several large, active fault systems, including the Elsinore‐Whittier, the
San Jacinto, and the San Andreas, occur in the region surrounding the
site. These fault systems have been studied extensively and in a large
part control the geologic structure of southern California.
4.3.3 Geologic Structure
Based upon our site investigation and literature review, the Pauba
Formation is neither folded, nor faulted.
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4.4 Groundwater
Groundwater was not encountered on site during our subsurface investigation.
Groundwater elevation data from the nearest active groundwater monitoring
site, Site ID: 334996N1171201W001 located approximately 0.7 miles southwest
of the site, indicates groundwater levels have ranged between 296.2‐ft and
337.0‐ft below the ground surface from 2011 to 2023.
4.5 Earthquake Hazards
The subject site is located in southern California, which is a tectonically active
area. The type and magnitude of seismic hazards affecting a site are dependent
on the distance to the causative fault and the intensity and magnitude of the
seismic event. The seismic hazard may be primary, such as surface rupture
and/or ground shaking, or secondary, such as liquefaction and/or ground
lurching.
4.5.1 Local and Regional Faulting
The site is located on the eastern portion of the Riverside sub‐block,
where the Elsinore, San Jacinto, Newport‐Inglewood, Rose Canyon, San
Joaquin Hills, Chino, and San Andreas faults surround the site at
approximately 1.7, 19.5, 29.6, 32.0, 33.3, 34.4, and 35.4 miles away,
respectively (USGS, 2008).
4.5.2 Seismicity
Ground shaking hazards caused by earthquakes along other active
regional faults do exist. The 2022 California Building Code requires use‐
modified spectral accelerations and velocities for most structural designs.
Seismic design parameters using soil profile types identified in the 2022
California Building Code are presented in Section 7.3.
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4.5.3 Surface Rupture
Active faults are not known to exist within the project and a review of
Special Publication 42 indicates the site is not within a California State
designated Earthquake Fault Zone (CGS, 2018). Accordingly, the potential
for fault surface rupture on the subject site is nil.
4.5.4 Liquefaction
Seismic agitation of relatively loose saturated sands, silty sands, and
some silts can result in a buildup of pore pressure. If the pore pressure
exceeds the overburden stresses, a temporary quick condition known as
liquefaction can occur. Liquefaction effects can manifest in several ways
including: 1) loss of bearing; 2) lateral spread; 3) dynamic settlement;
and 4) flow failure. Lateral spreading has typically been the most
damaging mode of failure.
In general, the more recent that a sediment has been deposited, the
more likely it will be susceptible to liquefaction. Other factors that must
be considered are: groundwater, confining stresses, relative density, and
the intensity and duration of seismically‐induced ground shaking.
Based on the density of the underlying Pauba Formation, the potential
for liquefaction is considered nil.
4.5.5 Dry Sand Settlement
Dry sand settlement is the process of settlement of the ground surface
during a seismic event in sand layers. Based on our subsurface
investigation and our removal/recompaction recommendations, the
potential for onsite dry sand settlement is anticipated to be negligible.
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4.6 Regional Subsidence
The site is located in an area designated as susceptible to subsidence by the
County of Riverside (RCIT, 2023). Upon implementation of the remedial grading
recommendations presented herein, the effects of subsidence on the
development are considered to be negligible.
5.0 ENGINEERING PROPERTIES AND ANALYSIS
5.1 Materials Properties
Presented herein is a general discussion of the engineering properties of the
onsite materials that will be encountered during construction of the proposed
development. Descriptions of the soil (Unified Soil Classification System) and in‐
place moisture/density results are presented on the boring logs in Appendix B.
5.1.1 Excavation Characteristics
Based on the data provided from the subsurface investigation, it is our
opinion that the onsite material possess favorable excavation
characteristics such that conventional earth moving equipment can be
utilized.
5.1.2 Compressibility
Any undocumented artificial fill, alluvium and the upper portions of the
Pauba Formation are considered compressible and unsuitable to support
the proposed improvements. Recommended removal depths are
presented in Section 6.1.2.
5.1.3 Hydro‐Consolidation
Hydro‐consolidation is the effect of introducing water into soil that is
prone to collapse. Upon loading and initial wetting, the soil structure and
apparent strength are altered resulting in almost immediate settlement.
That settlement can have adverse impacts on engineered structures,
particularly in areas where it is manifested differentially. Differential
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settlements are typically associated with differential wetting,
irregularities in the subsurface soil conditions, and/or irregular loading
patterns.
Based on laboratory testing (Appendix C), the potential for hydro‐
collapse onsite is minimal and should be within foundation tolerances
upon the completion of the recommended unsuitable soil removals.
5.1.4 Expansion Potential
Expansion index testing was performed on samples taken during the
previous subsurface investigation (Appendix C‐1). Based on the results
from the previous investigation, it is anticipated that the majority of
materials onsite vary from “very low” to “medium” in expansion potential
(0≤EI≤90, Appendix C) when tested per ASTM D: 4829.
5.1.5 Earthwork Adjustments
The values presented in Table 5‐1 are deemed appropriate for estimating
purposes and may be used in an effort to balance earthwork quantities.
As is the case with every project, contingencies should be made to adjust
the earthwork balance when grading is in‐progress and actual conditions
are better defined.
TABLE 5‐2
Earthwork Adjustment Factors
Geologic Unit Adjustment Factor Range Average
Artificial fill / alluvium / topsoil Shrink 12 to 17% 14%
Pauba Formation Shrink 2 to 4% 3%
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5.1.6 Chemical Analyses
Chemical testing was performed on a sample of material underlying the
site during the previous investigation. Soluble sulfate test results indicate
that the soluble sulfate concentrations of the soils tested are classified as
negligible to moderate (Class S0 to S1) per ACI 318‐14.
Negligible chloride levels were detected in the onsite soils. Based on
laboratory results of soluble sulfate, chloride, and pH testing as
presented in Appendix C, the onsite soils are classified as “non‐corrosive”
to buried metals and concrete (Caltrans, 2022). Additional discussions on
corrosion are presented in Section 7.9. Corrosion tests results are
presented in Appendix C.
5.2 Engineering Analysis
Presented below is a general discussion of the engineering analysis methods that
were utilized to develop the conclusions and recommendations presented in this
report.
5.2.1 Bearing Capacity and Lateral Earth Pressures
Ultimate bearing capacity values were obtained using the graphs and
formula presented in NAVFAC DM‐7.1. Allowable bearing was
determined by applying a factor of safety of at least 3 to the ultimate
bearing capacity. Static lateral earth pressures were calculated using
Rankine methods for active and passive cases. If it is desired to use
Coulomb forces, a separate analysis specific to the application can be
conducted.
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6.0 CONCLUSIONS AND RECOMMENDATIONS
Based on Alta’s findings during our subsurface investigation, the laboratory test results,
and our staff’s previous experience in the area, it is Alta’s opinion that the development
of the site is feasible from a geotechnical perspective. Presented below are
recommendations that should be incorporated into site development and construction
plans.
6.1 Remedial Grading Recommendations
All grading shall be accomplished under the observation and testing of the
project geotechnical consultant in accordance with the recommendations
contained herein and the County of Riverside criteria.
6.1.1 Site Preparation
Vegetation, construction debris, and other deleterious materials are
unsuitable as structural fill material and should be disposed of offsite
prior to commencing grading/construction. Any septic tanks, seepage
pits or wells should be abandoned as per the County of Riverside
Department of Health Services.
6.1.2 Unsuitable Soil Removals
Presented below are the unsuitable soil removal recommendations for
the onsite geologic units below the proposed future maintenance
building and parking lot. Removal bottoms should be observed by the
Project Geotechnical Consultant to make a final determination that
suitable, competent soils have been exposed. Removals should be
completed as per Plate G‐1 and G‐2 (Appendix E). In general, removals
shall expose competent Pauba Formation.
Existing concrete should be removed prior to the placement of
engineered fill. The demolished concrete may be incorporated into
compacted, engineered fills after it is crushed to a maximum size of six
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(6) inches. Prior to placement as engineered fill any protruding steel
rebar should be cut from the concrete pieces and disposed of offsite.
Existing asphaltic concrete should be removed prior to the placement of
engineered fill. From a geotechnical perspective, this material may be
incorporated into compacted, engineered fills after it is crushed to a
maximum size of six (6) inches. The crushed asphalt should not be placed
under structures, but rather, it can be placed in approved non‐structural
areas, such as streets, parking areas or open space. These
recommendations should be verified by the environmental consultant.
6.1.2.1 Future Maintenance Building
The highly weathered portions of the Pauba Formation onsite are
not suitable for the support of proposed structures and should be
removed and recompacted to project specifications prior to the
placement of compacted fill. It is anticipated that removal
recompaction depths in this unit will be approximately three (3)
feet in depth.
6.1.2.2 Parking Lot
For fill areas in parking lots/streets, in general, a minimum
removal and recompaction of the upper two (2) feet is
recommended, however all undocumented artificial fill shall be
removed and recompacted. For cuts greater than two (2) feet in
street areas, removals are not required. For cuts less than two (2)
feet, the two (2) foot removal and recompaction applies.
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6.1.3 Over‐Excavation of Building Pads
6.1.3.1 Cut/Fill Transition Pads
Where cut/fill transitions occur across building pads, Alta
recommends that the cut and shallow fill portions be over‐
excavated and replaced with compacted fill in order to provide
uniform bearing conditions.
The depth of the over‐excavation should provide a minimum of
three (3) feet of fill beneath the building and sufficiently deep to
provide a minimum thickness of 1/3 of the maximum fill thickness
beneath the building envelop, as shown on Plate G‐16 (Appendix
E).
The undercuts should be extended at least five (5) feet outside of
perimeter footings. The proposed undercuts should be graded
such that a gradient of at least one (1) percent is maintained
towards deeper fill areas or toward the front of the pad. The final
extent of the undercut should be verified in the field during
grading. Replacement fills should be compacted to project
specifications as discussed in Section 6.2.1.
6.1.3.2 Cut Pads
Alta recommends that the cut pads should be over‐excavated and
replaced with compacted fill in order to facilitate improvement
construction. The depth of the over‐excavation should provide a
minimum of three (3) feet of fill beneath the building pad. The
undercuts should be extended at least five (5) outside of
perimeter footings. The proposed undercuts should be graded
such that a gradient of at least one (1) percent is maintained
towards the front of the pad or toward deeper fill areas if present.
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The final extent of the undercut should be verified in the field
during grading. Replacement fills should be compacted to project
specifications as discussed in Section 6.2.1.
6.2 General Earthwork Recommendations
6.2.1 Compaction Standards
All fill and processed natural ground shall be compacted to a minimum
relative compaction of 90 percent, as determined by ASTM Test Method:
D‐1557. Fill material should be moisture conditioned to optimum
moisture or above, and as generally discussed in Alta’s Earthwork
Specification Section presented in Appendix D. Compaction shall be
achieved with the use of sheepsfoot rollers or similar kneading type
equipment. Mixing and moisture conditioning will be required in order to
achieve the recommended moisture conditions.
6.2.2 Groundwater/Seepage
It is anticipated that groundwater will not be encountered during grading.
It is possible that perched water conditions could be encountered in
areas depending on the time of year construction occurs.
6.2.3 Documentation of Removals
All removal/over‐excavation bottoms should be observed and approved
by the project Geotechnical Consultant prior to fill placement.
Consideration should be given to surveying the removal bottoms and
undercuts after approval by the geotechnical consultant and prior to the
placement of fill. Staking should be provided in order to verify undercut
locations and depths.
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6.2.4 Treatment of Removal Bottoms
At the completion of removals/over‐excavation, the exposed removal
bottom should be ripped to a minimum depth of eight (8) inches,
moisture‐conditioned to above optimum moisture content and
compacted in‐place to the project standards.
6.2.5 Fill Placement
After removals, scarification, and compaction of in‐place materials are
completed, additional fill may be placed. Fill should be placed in eight‐
inch bulk maximum lifts, moisture conditioned to optimum moisture
content or above, compacted and tested as grading/construction
progresses until final grades are attained.
6.2.6 Moisture Content
The moisture content of the upper in‐situ soils varies, as shown on the
boring logs in Appendix B. Moisture conditioning will be required during
grading to achieve optimum or above conditions.
6.2.7 Mixing
Mixing of materials may be necessary to prevent layering of different soil
types and/or different moisture contents. The mixing should be
accomplished prior to and as part of compaction of each fill lift.
6.2.8 Import Soils
Import soils, if necessary, should consist of clean, structural quality,
compactable materials similar to the on‐site soils and should be free of
trash, debris or other objectionable materials. The project Geotechnical
Consultant should be notified not less than 72 hours in advance of the
locations of any soils proposed for import. Import sources should be
sampled, tested, and approved by the project Geotechnical Consultant at
the source prior to the importation of the soils to the site. The project
Project Number 1‐0502 Page 16
November 15, 2023
ALTA CALIFORNIA GEOTECHNICAL, INC.
Civil Engineer should include these requirements on plans and
specifications for the project.
6.2.9 Utility Trenches
6.2.9.1 Excavation
Utility trenches should be supported, either by laying back
excavations or shoring, in accordance with applicable OSHA
standards. In general, existing site soils are classified as Soil Types
"B" and “C” per OSHA standards. Upon completion of the
recommended removals and re‐compaction, the artificial fill will
be classified as Soil Type "B". The Project Geotechnical Consultant
should be consulted if geologic conditions vary from what is
presented in this report.
6.2.9.2 Backfill
Trench backfill should be compacted to at least 90 percent of
maximum dry density as determined by ASTM D‐1557. Onsite
soils will not be suitable for use as bedding material but will be
suitable for use in backfill provided oversized materials are
removed. No surcharge loads should be imposed above
excavations. This includes spoil piles, lumber, concrete trucks, or
other construction materials and equipment. Drainage above
excavations should be directed away from the banks. Care should
be taken to avoid saturation of the soils. Compaction should be
accomplished by mechanical means. Jetting of native soils will not
be acceptable.
Under‐slab trenches should also be compacted to project
specifications. If select granular backfill (SE > 30) is used,
compaction by flooding will be acceptable.
Project Number 1‐0502 Page 17
November 15, 2023
ALTA CALIFORNIA GEOTECHNICAL, INC.
6.2.10 Fill Slope Construction
Fill slopes should be overfilled to an extent determined by the contractor,
but not less than two (2) feet measured perpendicular to the slope face,
so that when trimmed back to the compacted core a minimum 90
percent relative compaction is achieved.
Compaction of each fill lift should extend out to the temporary slope
face. Back‐rolling during mass filling at intervals not exceeding four (4)
feet in height is recommended, unless more extensive overfilling is
undertaken.
As an alternative to overfilling, fill slopes may be built to the finish slope
face in accordance with the following recommendations:
Compaction of each fill lift should extend to the face of the slopes.
Back‐rolling during mass grading should be undertaken at
intervals not exceeding four (4) feet in height. Back‐rolling at
more frequent intervals may be required.
Care should be taken to avoid spillage of loose materials down the
face of any slopes during grading. Spill fill will require complete
removal prior to compaction, shaping, and grid rolling.
At completion of mass filling, the slope surface should be
watered, shaped, and compacted by track walking with a D‐8
bulldozer, or equivalent, such that compaction to project
standards is achieved to the slope face.
Proper seeding and planting of the slopes should follow as soon as
practical to inhibit erosion and deterioration of the slope surfaces.
Proper moisture control will enhance the long‐term stability of the finish
slope surface.
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November 15, 2023
ALTA CALIFORNIA GEOTECHNICAL, INC.
6.2.11 Backcut Stability
Temporary backcuts, if required during unsuitable soil removals, should
be made no steeper than 1:1 without review and approval of the
geotechnical consultant. Flatter backcuts may be necessary where
geologic conditions dictate and where minimum width dimensions are to
be maintained.
Care should be taken during remedial grading operations in order to
minimize risk of failure. Should failure occur, complete removal of the
disturbed material will be required.
In consideration of the inherent instability created by temporary
construction backcuts for removals, it is imperative that grading
schedules are coordinated to minimize the unsupported exposure time of
these excavations. Once started, these excavations and subsequent fill
operations should be maintained to completion without intervening
delays imposed by avoidable circumstances. In cases where five‐day
workweeks comprise a normal schedule, grading should be planned to
avoid exposing at‐grade or near‐grade excavations through a non‐work
weekend. Where improvements may be affected by temporary
instability, either on or offsite, further restrictions such as slot cutting,
extending work days, implementing weekend schedules, and/or other
requirements considered critical to serving specific circumstances may be
imposed.
7.0 DESIGN CONSIDERATIONS
7.1 Structural Design
It is anticipated that a maintenance structure may be constructed onsite. It is
anticipated that the majority of onsite soils will possess "low" to "medium"
expansion potential when tested in general accordance with ASTM Test Method
Project Number 1‐0502 Page 19
November 15, 2023
ALTA CALIFORNIA GEOTECHNICAL, INC.
D: 4829. Final slab and foundation design recommendations should be made
based upon specific structure sitings and loading conditions.
Preliminary design recommendations for the proposed structures are presented
below. These parameters shall be verified as design of the project progresses.
Table 7‐1
Foundation/Slab Design Parameters*
Allowable Bearing 2000 lbs/ft2
Lateral Bearing 250 lbs/ft2 at a depth of 12 inches plus 250 lbs/ft2 for each
additional 12 inches of embedment to a maximum of 2000
lbs/ft2.
Sliding Coefficient 0.35
Settlement Static Settlement ‐ 0.50 inches in 40 feet
Dynamic Settlement – 0.50 inches in 40 feet
Modulus of Subgrade
Reaction
150 pci
Design Expansion Potential Medium
Design Plasticity Index 20
Under‐Slab Requirement See Section 7.2
Slab Subgrade Moisture Minimum of 120 percent of optimum moisture to a depth of
12‐inches prior to placing concrete.
*These values may be increased as allowed by Code to resist transient loads such as wind or
seismic. Building code and structural design considerations may govern depth and reinforcement
requirements and should be evaluated.
7.2 Moisture Barrier
A moisture and vapor retarding system should be placed below the slabs‐on‐
grade in portions of the structure considered to be moisture sensitive and should
be capable of effectively preventing the migration of water and reducing the
transmission of water vapor to acceptable levels. Historically, a 10‐mil plastic
membrane, such as Visqueen, placed between one to four inches of clean sand,
has been used for this purpose. The use of this system or other systems can be
considered, at the discretion of the designer, provided the system reduces the
vapor transmission rates to acceptable levels.
Project Number 1‐0502 Page 20
November 15, 2023
ALTA CALIFORNIA GEOTECHNICAL, INC.
7.3 Seismic Design
The site class was determined based on the subsurface investigation and
published geologic maps in the area in general conformance with Chapter 20 of
ASCE 7‐16. Based on density of the relatively shallow underlying Pauba
Formation, a Site Class of C was selected. Utilizing this information, the
computer program ATC Hazards by Location and ASCE 7‐16 criterion, the spectral
response accelerations that can be utilized for the project are presented in Table
7‐2. These parameters should be verified by the structural engineer. Additional
parameters should be determined by the structural engineer based on the
Occupancy Category of the proposed structures.
TABLE 7‐2 Seismic Ground Motion Values
2019 CBC and ASCE 7‐16
Parameter Value
Site Class C
Site Latitude 33.5026
Site Longitude ‐117.1109
Spectral Response Acceleration Parameter, SS 1.574
Spectral Response Acceleration Parameter, S1 0.586
Site Coefficient, Fa 1.2
Site Coefficient, Fv 1.414
MCE Spectral Response Acceleration Parameter, SMS 1.888
MCE Spectral Response Acceleration Parameter, SM1 0.828
Design Spectral Response Acceleration Parameter, SDS 1.259
Design Spectral Response Acceleration Parameter, SD1 0.552
Peak Ground Acceleration, PGAM 0.84
Project Number 1‐0502 Page 21
November 15, 2023
ALTA CALIFORNIA GEOTECHNICAL, INC.
7.4 Block Walls
Block walls, if used, should be embedded a minimum of 2 feet below the lowest
adjacent grade. Construction joints (not more than 20 feet apart) should be
included in the block wall construction.
7.5 Footing Excavations
Soils from the footing excavations should not be placed in slab‐on‐grade areas
unless properly compacted and tested. The excavations should be cleaned of all
loose/sloughed materials and be neatly trimmed at the time of concrete
placement. The Project Geotechnical Consultant should observe the footing
excavations prior to the placement of concrete to determine that the
excavations are founded in suitably compacted material.
7.6 Exterior Slabs and Walkways
Exterior concrete slabs and walkways should be designed and constructed in
consideration of the following recommendations.
7.6.1 Subgrade Compaction
The subgrade below exterior concrete slabs should be compacted to a
minimum of 90 percent relative compaction as determined by ASTM Test
Method: D 1557.
7.6.2 Subgrade Moisture
The subgrade below concrete slabs should be moisture conditioned to a
minimum of 110 percent of optimum moisture (low expansion) prior to
concrete placement or 120 percent of optimum moisture (medium
expansion) prior to concrete placement.
7.6.3 Concrete Slab Thickness
Concrete flatwork and driveways should be designed utilizing four‐inch
minimum thickness.
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November 15, 2023
ALTA CALIFORNIA GEOTECHNICAL, INC.
7.6.4 Concrete Slab Reinforcement
Utilization of reinforcement for flatwork and driveways is subject to a
cost/benefit analysis. Reinforcement will decrease the amount of
cracking that may occur in flatwork, however, planning for occasional
repairs may be more cost effective. Utilizing closely spaced control joints
is likely more cost‐effective than utilizing reinforcement. The majority of
the soils onsite are classified as very low to medium in expansion
potential. Consideration should be given to reinforcing flatwork with
irregular (non‐square/rectangular) shapes or flatwork underlain by
medium expansive soils. Reinforcement may consist of 6x6 W.14/W1.4
welded wire mesh or and equivalent section of rebar.
7.6.5 Control Joints
Weakened plane joints should be installed on walkways at intervals of
approximately eight feet (maximum) or less. Exterior slabs should be
designed to withstand shrinkage of the concrete.
7.7 Concrete Design
As stated in Section 5.1.6, negligible concentrations of sulfates were detected in
the onsite soils. Therefore, the use of sulfate resistant concrete is not required
per ACI 318‐14 at this time. Post‐grading conditions should be evaluated, and
final recommendations made at that time.
7.8 Corrosion
Based on preliminary testing, the onsite soils are not considered corrosive to
buried metal objects per Caltrans standards. Buried ferrous metals should be
protected against the effects of corrosive soils in accordance with the
manufacturer’s recommendations. Typical measures may include using non‐
corrosive backfill, protective coatings, wrapping, plastic pipes, or a combination
Project Number 1‐0502 Page 23
November 15, 2023
ALTA CALIFORNIA GEOTECHNICAL, INC.
of these methods. A corrosion engineer should be consulted if specific design
recommendations are required by the improvement designer.
Per ACI 318‐14, an exposure class of C1 would be applicable to metals encased in
concrete (rebar in footings) due to being exposed to moisture from surrounding
soils. Per Table 19.3.2.1 of ACI 318‐14, the requirements for concrete with an
exposure class of C1 are a minimum compressive strength of 2500 psi and a
maximum water‐soluble chloride ion content in concrete of 0.30 (percent by
weight of cement).
7.9 Pavement Design
Pavement sections for the proposed streets/parking lots shall be designed based
on laboratory testing conducted on samples taken from the soil subgrade. Based
on an assumed R‐Value of 20, the pavement may be designed utilizing the
sections presented in Table 7‐3. These sections should be verified upon the
completion of grading, based on R‐Value testing. The ultimate pavement section
design for public streets is under the County of Riverside’s purview.
Table 7‐3
Preliminary Pavement Sections
Traffic Index Pavement Section Options
OR
5.0 3‐inch AC on 7.5‐inch AB 4‐inch AC on 6‐inch AB
AC‐Asphalt Concrete
AB‐Caltrans Class II Base
Construction of the streets should be accomplished in accordance with the
current criteria of the County of Riverside. Prior to the placement of base
material, the subgrade should be suitably moisture conditioned, processed and
compacted to a minimum 95 percent of the laboratory maximum density (ASTM:
D 1557) to at least twelve (12) inches below subgrade. After subgrade
compaction, the exposed grade should then be "proof"‐rolled with heavy
equipment to ensure the grade does not "pump" and is verified as non‐yielding.
Project Number 1‐0502 Page 24
November 15, 2023
ALTA CALIFORNIA GEOTECHNICAL, INC.
Aggregate base material should be placed on the compacted subgrade and
compacted in‐place to a minimum 95 percent of the laboratory standard
obtained per ASTM: D 1557.
7.10 Site Drainage
Positive drainage away from the proposed structures should be provided and
maintained. Roof, pad, and lot drainage should be collected and directed away
from the structures toward approved disposal areas through drainage terraces,
gutters, down drains, and other devices. Design fine grade elevations should be
maintained through the life of the structure or if design fine grade elevations are
altered, adequate area drains should be installed in order to provide rapid
discharge of water, away from structures.
7.11 Deepened Footings and Setbacks
It is generally recognized that improvements constructed in proximity to
properly constructed slopes can, over a period of time, be affected by natural
processes including gravity forces, weathering of surficial soils and long term
(secondary) settlement. Most building codes, including the California Building
Code (CBC), require that structures be setback or footings deepened, where
subject to the influence of these natural processes. For the subject site, where
foundations for residential structures are to exist in proximity to slopes, the
footings should be embedded to satisfy the requirements presented in the
following figure.
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November 15, 2023
ALTA CALIFORNIA GEOTECHNICAL, INC.
H
H/2, need not be more than 15 feet
H/2 when H < 30 feet, need not exceed 10 feet, but not less than 5 feet.
H/3 when H >30 feet, need not exceed 40 feet.
Consideration of these natural processes should be undertaken in the design and
construction of other improvements. Homeowners are advised to consult with
qualified geotechnical engineers, designers, and contractors in the design and
construction of future improvements. Each lot and proposed improvement
should be evaluated in relation to the specific site conditions, accounting for the
specific soil conditions.
8.0 LOT MAINTENANCE
Ongoing maintenance of the improvements is essential to the long‐term performance of
structures. The following recommendations should be implemented.
8.1 Lot Drainage
Roof, pad and lot drainage should be collected and directed away from
structures and slopes and toward approved disposal areas. Design fine grade
elevations should be maintained throughout the life of the structure or if design
fine grade elevations are altered, adequate area drains should be installed in
order to provide rapid discharge of water, away from structures and slopes.
Owners should be made aware that they are responsible for maintenance and
cleaning of all drainage terraces, down drains, and other devices that have been
installed to promote structure and slope stability.
Project Number 1‐0502 Page 26
November 15, 2023
ALTA CALIFORNIA GEOTECHNICAL, INC.
8.2 Burrowing Animals
Owners should undertake a program for the elimination of burrowing animals.
9.0 FUTURE PLAN REVIEWS
This report represents a geotechnical review of the site. As the project design for the
project progresses, site specific geologic and geotechnical issues should be considered in
the design and construction of the project. Consequently, future plan reviews may be
necessary. These reviews may include reviews of:
Grading Plans
Foundation Plans
Utility Plans
These plans should be forwarded to the project Geotechnical Consultant for review.
10.0 CLOSURE
10.1 Geotechnical Review
For the purposes of this report, multiple working hypotheses were established
for the project, utilizing the available data and the most probable model is used
for the analysis. Future information collected during the proposed grading
operations is intended to evaluate the hypothesis and as such, some of the
assumptions summarized in this report may need to be changed. Some
modifications of the grading recommendations may become necessary, should
the conditions encountered in the field differ from the conditions hypothesized
in this report.
Plans and sections of the project specifications should be reviewed by Alta to
evaluate conformance with the intent of the recommendations contained in this
report. If the project description or final design varies from that described in
herein, Alta must be consulted regarding the applicability of the
recommendations contained herein and whether any changes are required. Alta
Project Number 1‐0502 Page 27
November 15, 2023
ALTA CALIFORNIA GEOTECHNICAL, INC.
accepts no liability for any use of its recommendations if the project description
or final design varies and Alta is not consulted regarding the alterations.
10.2 Limitations
This report is based on the following: 1) the project as presented on the attached
plan; 2) the information obtained from Alta's laboratory testing included herein;
and 3) from the information presented in the referenced reports. The findings
and recommendations are based on the results of the subsurface investigation,
laboratory testing, and office analysis combined with an interpolation and
extrapolation of conditions between and beyond the subsurface excavation
locations. However, the materials adjacent to or beneath those observed may
have different characteristics than those observed, and no precise
representations are made as to the quality or extent of the materials not
observed. The results reflect an interpretation of the direct evidence obtained.
Work performed by Alta has been conducted in a manner consistent with the
level of care and skill ordinarily exercised by members of the geotechnical
profession currently practicing in the same locality under similar conditions. No
other representation, either expressed or implied, and no warranty or guarantee
is included or intended.
The recommendations presented in this report are based on the assumption that
an appropriate level of field review will be provided by a geotechnical consultant
who is familiar with the design and site geologic conditions. That field review
shall be sufficient to confirm that geotechnical and geologic conditions exposed
during grading are consistent with the geologic representations and
corresponding recommendations presented in this report.
The conclusions and recommendations included in this report are applicable to
the specific design of this project as discussed in this report. They have no
Project Number 1‐0502 Page 28
November 15, 2023
ALTA CALIFORNIA GEOTECHNICAL, INC.
applicability to any other project or to any other location and any and all
subsequent users accept any and all liability resulting from any use or reuse of
the data, opinions, and recommendations without the prior written consent of
Alta.
Alta has no responsibility for construction means, methods, techniques,
sequences, procedures, safety precautions, programs in connection with the
construction, acts or omissions of the CONTRACTOR or any other person
performing any of the construction, or for the failure of any of them to carry out
the construction in accordance with the final design drawings and specifications.
ALTA CALIFORNIA GEOTECHNICAL, INC.
APPENDIX A
REFERENCES
Project Number 1‐0502 Page A‐1
November 15, 2023
ALTA CALIFORNIA GEOTECHNICAL, INC.
APPENDIX A
References
Alta California Geotechnical, Inc., 2015, Geotechnical Investigation, Linfield Property, Tract
36098‐1, Parcels 1 through 3, and Tract 36098‐2, Parcel 1, City of Temecula, California dated
June 15, 2015 (Project Number 1‐0155A).
Alta California Geotechnical, Inc., 2015, Geotechnical Investigation, Eastern Portion of the
Linfield Property, A Portion of Tract 36098‐3, City of Temecula, California dated June 15,
2015 (Project Number 1‐0155).
California Code of Regulations, 2022, California Building Code, Title 24, Part 2, Volume 2, Based
on the 2018 International Building Code, Effective Date January 1, 2023.
California Department of Water Resources, 2023, online information:
http://www.water.ca.gov/waterdatalibrary/index.cfm.
California Department of Transportation (Caltrans), 2022, Caltrans Geotechnical Manual,
published March, 2022.
California Geological Survey, 2018, Earthquake Fault Zones, A Guide For Government Agencies,
Property Owners/Developers, and Geoscience Practitioners for Assessing Fault Rupture
Hazards in California, Special Publication 42, revised 2018.
Historic Aerials, 2023, www.historicaerials.com, by NETROnline, Copyright 1999‐2020, accessed
October 2023.
Jennings, C.W., and Bryant, W.A., 2010, Fault Activity Map of California: California Geological
Survey Geologic Data Map No. 6, map scale 1:750,000.
Jennings, C. W., and Bryant, W.A., 2010, An explanatory text to accompany the 1:750,000 scale
fault and geologic map of California: California Division of Mines and Geology, special
publication 42, revised 1985, 24 p.
Jennings, C. W., 1985, An explanatory text to accompany the 1:750,000 scale fault and geologic
maps of California: California Division of Mines and Geology, Bulletin 201, 197 p.
Morton, D.M., Kennedy, M.P., Bovard, K.R., and Burns, Diane, 2003, Geologic map and digital
database of the Bachelor Mountain 7.5' quadrangle, Riverside County, California, U.S.
Geological Survey, Open‐File Report OF‐2003‐103, 1:24,000.
Riverside County RCIT, 2023,
https://gis1countyofriverside.us/html5viewer/?viewer=mmc_public
Romanoff, Melvin, 1989, Underground Corrosion, NBS Circular 579, Reprinted by NACE,
Houston, TX, 1989.
Project Number 1‐0502 Page A‐2
November 15, 2023
ALTA CALIFORNIA GEOTECHNICAL, INC.
U.S. Geological Survey, 2008, National Seismic Hazards Maps – Source Parameters,
http://geohazards.usgs.gove/cfusion/hazfaults_2008_search/query_maine.cfm
ALTA CALIFORNIA GEOTECHNICAL, INC.
APPENDIX B
Subsurface Investigation
Project Number 1‐0502 Page B‐1
November 15, 2023
ALTA CALIFORNIA GEOTECHNICAL, INC.
APPENDIX B
Subsurface Investigation
Alta's subsurface investigation consisted of excavating, logging, and sampling five (5) hollow‐
stem auger borings. Details of the subsurface investigation are presented in Table B‐1. The
approximate locations of the exploratory excavations are shown on the accompanying plan
(Plate 1) and the Geotechnical Logs are attached.
TABLE B‐1
SURFACE INVESTIGATION DETAILS
Equipment Range of
Depths
Sampling Methods Sample Locations
Hollow‐
Stem Auger
Up to 25 feet 1. Bulk
2. Ring or SPT
1. Bulk‐Select Depth
2. Ring‐Every 2.5 to 5‐ft
UNIFIED SOI L CLASSIFIICATION SYSTEM
Major Divisions lfl tr Description Major Divisions an tr
Coarse
Grained
Soils
N4ore than
50%
retained on
No 200
steve
Gravel
and
Sravelly
Soils
han 50%
frachon
relained
on No, 4
'l
ts*
,-l*
EIF
GW
Well-graded grcvels or gravel sand
mixtures, little or no fines
Fine
(lrained
isoils
l\lore than
Silts
And
Clays
LL,<50 n
ML
Inorganic silts and very fine sands,
rock flour, silty or clayey fine sands
or clavev silts with slioht olasticitv
GP
Poorly-graded gravels or gravel
sand mixture, little or no fines CL
Inorganic clays of low to medium
plasticity, gravelly clays, sandy
clays, silty clays, lean claysSilty gravels, gravel-sand-silt
mixtures
OL
Organic silts and organic silt-clays
of low plasticity
Clayey gravels, gravel-sand-clay
mixtures
Silts
And
Clays
LL,<50
MF
Inorganic silts, micaceous or
diatomaceous fine or silty soils,
elastic siltsSand
and
Sandy
Soils
than 50%
fraclion
Passes
on No, 4
i'+.
3_'.JV!
Well-graded sands or gravelly
sands, little or no fines
on No 200
steve VH
Inorganic clays of high plasticity,
fat claysSP
Poorly-graded sands or gravelly
sands, little or no fines
SM Silty sands, sarrd-silt mixtures OF
Organic clays of medium to high
plasticity
sc Clayey sands, and-clay mixtures Highly Organic
Soils PT Peat and other highly organic soils
BoUNDARY CLASSIFICATIoN: Soils possessing characteristics of two groups are designated by combinations of group symbols
PARTICLE SIZ:E LIMITS
U.S. STANDA,RD SiERIES SIEVE
200 40 10 4
CLEAR SQUARE SIEVE OPENINGS
3t4" 3,, ,t2"
LABORATORY TESTS
Symbol Tesl
DS
DSR
cc)N
SA
MAX
RV
EI
SE
AL
CHEM
HY
Direct Shear
Direct Shear
(Remolded)
Sieve Analysis
Maximum Density
Resistance (R) Value
Expansion Index
Sand Equivalent
Atterberg Limits
Chemical Analysis
Hydrometer Analysis
SOIL MOISTURE SIZE PROPORTIONS
Trace - <5%
Few-5to10%
Some - 15 to 25%
Increasing \/isual Moisture Content
Silts
an0
Clays
Sand Gravel
Cobbles Boulders
Fine Medium Coarsi€r Fine Coarse
RELATIVE DENSITY
Sands and Gravels Blows/Foot (SPT)
Very Loose
Loose
Medium Dense
Dense
Very Dense
<4
4-10
11-30
31 -50
>50
CON SI STENCY C IASSI FI CATI ON
Silts and Clays Criteria
Very Soft
Soft
Firm
stiff
Very Stiff
Thumb penetrates soil >1 in.
Thumb penetrates soil 1 in,
Thumb penetrates soil 1/4 in
Readily indented with thumbnail
Thumbnail will not indent soil
HARDNESS
KEY TO EXPLORATORY BORING LOGS}
,n
/L>//J, ALTA CALIFORNTA GEOTECHNTCAL tNC.
/\
PI-ATE B
TOPSOIL: SILTY SAND, fine grained, brown, dry, medium dense
PAUBA FORMATION (Qp): SANDY CLAY, reddish brown, slightly
moist, firm
@5.0 ft. CLAYEY SAND, medium grained, white brown, moist, very
dense
@10.0 ft. SAND, medium grained, brown, moist, very dense, trace
clay
@15.0 ft. fine grained, white brown, dense
@15.5 ft. CLAY, reddish brown, moist, firm
@20.5 ft. SAND, fine grained, greenish brown, moist, very dense,
trace clay
TOTAL DEPTH 21.0 FEET
GROUNDWATER NOT ENCOUNTERED
NO CAVING OBSERVED
R
R
R
R
R
29
70
83
47
34/50 for
5"
7.0
8.6
10.0
14.4
11.6
47
60
86
98
83
119
120
126
119
121
SM
CL
SC
SP
CL
SP
5
10
15
20
TYPE OF DRILL RIG
DRILLER
SA
T
-
CO
N
T
(
%
)
MO
I
S
T
U
R
E
10/19/23
(%
)
UR
A
T
I
O
N
DATE STARTED 10/19/23
1220
1215
1210
1205
1200
GEOTECHNICAL DESCRIPTION
OT
H
E
R
SA
M
P
L
E
EL
E
V
DE
N
S
I
T
Y
DR
Y
(
p
c
f
)
BORING DESIG.
DROP
DRIVE WT.
GW DEPTH (FT)
PROJECT NAME
DATE FINISHED YH
DE
P
T
H
VARIES*
Linfield Christian School
TE
S
T
S
S SPT (SPLIT SPOON) SAMPLE
R RING (DRIVE) SAMPLE
SAMPLE TYPES:
SHEET
NOTE
LOGGED BY
GR
O
U
P
J: JOINTING
B: BEDDING
S: SHEAR
C: CONTACT
F: FAULT
RS: RUPTURE SURFACE
1-0502
GROUNDWATER
SEEPAGE
(F
e
e
t
)
PROJECT NO.
GEOTECHNICAL BORING LOG
GROUND ELEV.
8" Hollow Stem Auger
2R
SY
M
B
O
L
LI
T
H
O
L
O
G
Y
BL
O
W
S
T TUBE SAMPLEB BULK SAMPLE
TY
P
E
1 OF 1
12 in.
B-11220
Alta California Geotechnical, Inc.
P.N. 1-0502 PLATE B-1
TOPSOIL: SILTY SAND, fine grained, brown, dry, medium dense
PAUBA FORMATION (Qp): SAND, fine grained, brown, slightly
moist, very dense
@2.5 ft. trace clay
@5.0 ft. SILTY CLAY, brown, moist, firm
@10.0 ft. SAND, medium grained, gray tan, slightly moist, very
dense
@15.0 gray brown
@20.0 ft. gray tan, trace clay
TOTAL DEPTH 21.0 FEET
GROUNDWATER NOT ENCOUNTERED
NO CAVING OBSERVED
R
R
R
R
R
61
52
92
30/50 for
6"
65
10.1
16.7
5.4
5.5
5.8
54
89
33
40
34
111
110
116
121
114
SM
SP
CL
SP
5
10
15
20
TYPE OF DRILL RIG
DRILLER
SA
T
-
CO
N
T
(
%
)
MO
I
S
T
U
R
E
10/19/23
(%
)
UR
A
T
I
O
N
DATE STARTED 10/19/23
1220
1215
1210
1205
1200
GEOTECHNICAL DESCRIPTION
OT
H
E
R
SA
M
P
L
E
EL
E
V
DE
N
S
I
T
Y
DR
Y
(
p
c
f
)
BORING DESIG.
DROP
DRIVE WT.
GW DEPTH (FT)
PROJECT NAME
DATE FINISHED YH
DE
P
T
H
VARIES*
Linfield Christian School
TE
S
T
S
S SPT (SPLIT SPOON) SAMPLE
R RING (DRIVE) SAMPLE
SAMPLE TYPES:
SHEET
NOTE
LOGGED BY
GR
O
U
P
J: JOINTING
B: BEDDING
S: SHEAR
C: CONTACT
F: FAULT
RS: RUPTURE SURFACE
1-0502
GROUNDWATER
SEEPAGE
(F
e
e
t
)
PROJECT NO.
GEOTECHNICAL BORING LOG
GROUND ELEV.
8" Hollow Stem Auger
2R
SY
M
B
O
L
LI
T
H
O
L
O
G
Y
BL
O
W
S
T TUBE SAMPLEB BULK SAMPLE
TY
P
E
1 OF 1
12 in.
B-21220
Alta California Geotechnical, Inc.
P.N. 1-0502 PLATE B-2
ALLUVIUM(Qal): SILTY SAND, medium grained, brown, dry, loose
PAUBA FORMATION (Qp): SILTY SAND, fine grained, brown,
moist, very dense, trace clay
@5.0 ft. dark brown, slightly moist, dense, trace carbonates
@10.0 ft. SAND, medium grained, white gray brown, slightly moist,
very dense, trace pebbles, trace gravel
@15.0 ft. pink tan, slightly moist, very dense, trace pebbles
@20.5 ft. SANDY CLAY, greenish brown, moist, firm, trace orange
mottling
TOTAL DEPTH 21.0 FEET
GROUNDWATER NOT ENCOUNTERED
NO CAVING OBSERVED
R
R
R
R
R
12/38/50
for 4"
33
35/38/50
for 5"
57
25/45
9.2
6.7
4.9
9.5
9.3
78
41
47
42
71
CON,
HY
126
115
130
104
123
SM
SM
SP
CL
5
10
15
20
TYPE OF DRILL RIG
DRILLER
SA
T
-
CO
N
T
(
%
)
MO
I
S
T
U
R
E
10/19/23
(%
)
UR
A
T
I
O
N
DATE STARTED 10/19/23
1220
1215
1210
1205
1200
GEOTECHNICAL DESCRIPTION
OT
H
E
R
SA
M
P
L
E
EL
E
V
DE
N
S
I
T
Y
DR
Y
(
p
c
f
)
BORING DESIG.
DROP
DRIVE WT.
GW DEPTH (FT)
PROJECT NAME
DATE FINISHED YH
DE
P
T
H
VARIES*
Linfield Christian School
TE
S
T
S
S SPT (SPLIT SPOON) SAMPLE
R RING (DRIVE) SAMPLE
SAMPLE TYPES:
SHEET
NOTE
LOGGED BY
GR
O
U
P
J: JOINTING
B: BEDDING
S: SHEAR
C: CONTACT
F: FAULT
RS: RUPTURE SURFACE
1-0502
GROUNDWATER
SEEPAGE
(F
e
e
t
)
PROJECT NO.
GEOTECHNICAL BORING LOG
GROUND ELEV.
8" Hollow Stem Auger
2R
SY
M
B
O
L
LI
T
H
O
L
O
G
Y
BL
O
W
S
T TUBE SAMPLEB BULK SAMPLE
TY
P
E
1 OF 1
12 in.
B-31220
Alta California Geotechnical, Inc.
P.N. 1-0502 PLATE B-3
TOPSOIL: SILTY SAND, fine grained, brown, dry, medium dense
PAUBA FORMATION (Qp): CLAYEY SAND, fine grained, reddish
brown, moist, very dense, some roots in top 2.5 feet
@5.0 ft. CLAYEY SILT, brown, slightly moist, firm, trace sand
@10.0 ft. CLAYEY SAND, medium grained, brown, moist, very
dense, trace silt
@15.0 ft. SAND, medium grained, gray tan, slightly moist, very
dense
20.0 ft. trace pebbles
TOTAL DEPTH 21.0 FEET
GROUNDWATER NOT ENCOUNTERED
NO CAVING OBSERVED
R
R
R
R
R
7/30/50
for 6"
30/50 for
5"
30/50 for
3"
33/50 for
4"
30/40/50
for 5"
8.4
6.0
7.3
5.3
4.5
82
51
75
26
29
130
126
131
108
118
SM
SC
ML
SC
SP
5
10
15
20
TYPE OF DRILL RIG
DRILLER
SA
T
-
CO
N
T
(
%
)
MO
I
S
T
U
R
E
10/19/23
(%
)
UR
A
T
I
O
N
DATE STARTED 10/19/23
1220
1215
1210
1205
1200
GEOTECHNICAL DESCRIPTION
OT
H
E
R
SA
M
P
L
E
EL
E
V
DE
N
S
I
T
Y
DR
Y
(
p
c
f
)
BORING DESIG.
DROP
DRIVE WT.
GW DEPTH (FT)
PROJECT NAME
DATE FINISHED YH
DE
P
T
H
VARIES*
Linfield Christian School
TE
S
T
S
S SPT (SPLIT SPOON) SAMPLE
R RING (DRIVE) SAMPLE
SAMPLE TYPES:
SHEET
NOTE
LOGGED BY
GR
O
U
P
J: JOINTING
B: BEDDING
S: SHEAR
C: CONTACT
F: FAULT
RS: RUPTURE SURFACE
1-0502
GROUNDWATER
SEEPAGE
(F
e
e
t
)
PROJECT NO.
GEOTECHNICAL BORING LOG
GROUND ELEV.
8" Hollow Stem Auger
2R
SY
M
B
O
L
LI
T
H
O
L
O
G
Y
BL
O
W
S
T TUBE SAMPLEB BULK SAMPLE
TY
P
E
1 OF 1
12 in.
B-41220
Alta California Geotechnical, Inc.
P.N. 1-0502 PLATE B-4
TOPSOIL: SILTY SAND, fine grained, brown, dry, medium dense
PAUBA FORMATION (Qp): SILTY SAND, fine grained, brown tan,
moist, very dense
@5.0 ft. trace clay
@10.0 ft. SAND, medium grained, gray white tan, slightly moist, very
dense, trace carbonates
TOTAL DEPTH 21.0 FEET
GROUNDWATER NOT ENCOUNTERED
NO CAVING OBSERVED
R
R
R
R
R
10/28/50
for 3"
50 for 6"
27/50 for
5"
41/50 for
5"
30/40/50
for 5"
8.7
6.9
5.5
6.6
7.5
64
59
35
40
41
CON,
HY
122
126
117
115
112
SM
SM
SP
5
10
15
20
TYPE OF DRILL RIG
DRILLER
SA
T
-
CO
N
T
(
%
)
MO
I
S
T
U
R
E
10/19/23
(%
)
UR
A
T
I
O
N
DATE STARTED 10/19/23
1220
1215
1210
1205
1200
GEOTECHNICAL DESCRIPTION
OT
H
E
R
SA
M
P
L
E
EL
E
V
DE
N
S
I
T
Y
DR
Y
(
p
c
f
)
BORING DESIG.
DROP
DRIVE WT.
GW DEPTH (FT)
PROJECT NAME
DATE FINISHED YH
DE
P
T
H
VARIES*
Linfield Christian School
TE
S
T
S
S SPT (SPLIT SPOON) SAMPLE
R RING (DRIVE) SAMPLE
SAMPLE TYPES:
SHEET
NOTE
LOGGED BY
GR
O
U
P
J: JOINTING
B: BEDDING
S: SHEAR
C: CONTACT
F: FAULT
RS: RUPTURE SURFACE
1-0502
GROUNDWATER
SEEPAGE
(F
e
e
t
)
PROJECT NO.
GEOTECHNICAL BORING LOG
GROUND ELEV.
8" Hollow Stem Auger
2R
SY
M
B
O
L
LI
T
H
O
L
O
G
Y
BL
O
W
S
T TUBE SAMPLEB BULK SAMPLE
TY
P
E
1 OF 1
12 in.
B-51220
Alta California Geotechnical, Inc.
P.N. 1-0502 PLATE B-5
ALTA CALIFORNIA GEOTECHNICAL, INC.
APPENDIX B‐1
Previous Subsurface Investigation
(Alta, 2016)
(Alta, 2015)
ALTA CALIFORNIA GEOTECHNICAL, INC.
APPENDIX C
Laboratory Testing
Project Number 1‐0502 Page C‐1
November 15, 2023
ALTA CALIFORNIA GEOTECHNICAL, INC.
LABORATORY TESTING
The following laboratory tests were performed on a representative sample in accordance with
the applicable latest standards or methods from the ASTM, California Building Code (CBC) and
California Department of Transportation.
Classification
Soils were classified with respect to the Unified Soil Classification System (USCS) in accordance
with ASTM D‐2487 and D‐2488.
Particle Size Analysis
Modified hydrometer testing was conducted to aid in classification of the soil. The results of
the particle size analysis are presented in Table C.
Expansion Index Tests
One (1) expansion index test was performed to evaluate the expansion potential of typical on‐
site soil. Testing was carried out in general conformance with ASTM Test Method D‐4829. The
results are presented in Table C.
Consolidation Tests
Consolidation testing was performed on one (1) relatively “undisturbed” soil samples at their
natural moisture content in accordance with procedures outlined in ASTM D‐2435. The sample
was placed in a consolidometer and loads were applied incrementally in geometric progression.
The sample (2.42‐inches in diameter and 1‐inch in height) was permitted to consolidate under
each load increment until the slope of the characteristic linear secondary compression portion
of the thickness versus log of time plot was apparent. The percent consolidation for each load
cycle was recorded as the ratio of the amount of vertical compression to the original 1‐inch
height. The consolidation test results are shown on Plate C‐1.
Chemical Analyses
Chemical testing was performed on one select sample. The results of this test (sulfate content,
resistivity, chloride content and pH) is presented on Table C.
B-1 3 Silty Sand (Qp) SM 1 65 18 16 5
Sulf: 0.001% Chlr: 75ppm pH:
8.1, Resis: 3,811 Ohm-cm
B-3 5 Silty Sand (Qoa) SM 0 76 9 15
SEE PLATE
C-1
B-5 2.5 Silty Sand (Qoa) SM 0 52 31 17
OTHER TESTS
REMARKS
BORING DEPTH
(FEET)
SOIL DESCRIPTION GROUP
SYMBOL
DIRECT
SHEAR
EXPANSION
INDEX
UBC 18-2
MAXIMUM
DENSITY
(PCF)
TABLE C
SUMMARY OF LABORATORY TEST DATA
P.N. 1-0502
OPTIMUM
MOISTURE
CONTENT
(%)
CONSOLSILT
(0.075mm-0.005mm)
(%)
SAND
(4.76mm-0.075mm)
(%)
PLUS NO.4 SEIVE
(plus 4.76mm)
(%)
CLAY
(minus 0.005mm)
(%)
Alta California Geotechnical, Inc.
-2.0
-1.0
0
1.0
2.0
3.0
4.0
5.0
6.0
7.0
8.0
0.1 2 3 4 5 6 7 8 9 1 2 3 4 5 6 7 8 9 10
REMARKS: WATER ADDED AT 1.07 TSF
CONSOLIDATION CURVE
PE
R
C
E
N
T
C
H
A
N
G
E
I
N
H
E
I
G
H
T
PLATE C-1
COMPRESSIVE STRESS IN TSF
satur. (%)
115
-200
Silty Sand (Qoa)SM
boring in situ
41
group typical namessymbolsieve (%)density (pcf)
6.7
moist. (%)
in situdrydepth (ft.)
5.0B-3 24
Alta California Geotechnical, Inc.
P.N. 1-0502
ALTA CALIFORNIA GEOTECHNICAL, INC.
APPENDIX D
Earthwork Specifications
ALTA CALIFORNIA GEOTECHNICAL, INC.
APPENDIX E
Grading Details
T-1Qp
afu
(Qp)
Qp Qp
B-4
P-1
T-20
B-1
0-1.5' Qal
1.5'-2.5' Qp
No H2O
Qal
B-2
0-1' af
1'-5' Qp
5'-11' Qp
No H2O
Qal
(Qp)
afu
(Qp)
B-5
Qal
(Qp)
0'-5.5' Qal
5.5'-6.5' Qp
No H2O
T-17
0'-2.5' Qp
No H2O
T-19
Qp
afu
(Qal)
afu
(Qp)
B-3 Qp
afu
(Qal)
PLATE 1
170 N. MAPLE STREET, STE 108, CORONA, CA 92880
TELEPHONE: (951) 509-7090
ALTA CALIFORNIA GEOTECHNICAL, INC.
LEGEND
Artificial Fill-Undocumented
Alluvium (bracketed where buried)
Pauba Formation (bracketed where buried)
Geologic Contact (dotted where buried)
Approximate Location of Backhoe Test Pit
Approximate Location of Hollow Stem Auger Boring
Approximate Location of Infiltration Test
Approximate Limits of Report
afu
Qal
H-4
P-1
T-20