HomeMy WebLinkAboutRG23-0005+Soils+ReportPRELIMINARY GEOTECHNICAL EXPLORATION –
DUE DILIGENCE
REFUGE PALM DESERT, APPROXIMATELY 79 ACRE
DEL WEBB PROPERTY
PALM DESERT, CALIFORNIA
Prepared For
27401 LOS ALTOS, SUITE 400
MISSION VIEJO, CA 92691
Prepared By LEIGHTON AND ASSOCIATES, INC.
41945 BOARDWALK, SUITE V
PALM DESERT, CA 92211
August 10, 2022
Project No. 13629.001
Pulte Home Corporation
27101 Puerta Real, Suite 300
Mission Viejo, CA 92691
Attention: Mr. David Dewegeli
Subject: Preliminary Geotechnical Exploration – Due Diligence
Refuge Palm Desert, Approximately 79 Acre Del Webb Property
Palm Desert, California
In accordance with your request and authorization, we are pleased to present herewith
the results of our geotechnical exploration for the subject site located southwest of the
intersection of Gerald Ford Drive and Portola Avenue, in the City of Palm Desert,
California. This report summarizes our findings and conclusions and provides preliminary
geotechnical recommendations for site development. Based on the results of this
evaluation, the site appears suitable for the intended use provided our recommendations
included herein are properly incorporated during design and construction phases of
development. However, it should be noted that additional geotechnical evaluations or
review will be required as site development and/or grading plans become available.
If you have any questions regarding this report, please do not hesitate to contact the
undersigned. We appreciate this opportunity to be of service on this project.
Respectfully submitted,
LEIGHTON AND ASSOCIATES, INC.
Senior Project Engineer President / Sr. Principal Geologist
Distribution: (1) Addressee
Preliminary Geotechnical Exploration – Due Diligence August 10, 2022
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T A B L E O F C O N T E N T S
Section Page
1.0 I N T R O D U C T I O N ........................................................................................... 1
1.1 Purpose and Scope ............................................................................................. 1
1.2 Site Location and Description ............................................................................. 1
1.3 Proposed Development ....................................................................................... 2
2.0 FIELD EXPLO RATIO N AN D LABORATORY TESTI NG ............... 3
2.1 Previous Studies ................................................................................................. 3
2.2 Field Exploration .................................................................................................. 3
2.3 Laboratory Testing .............................................................................................. 3
3.0 GEOTECHNI CAL AND GEO LO GIC FI NDING S ................................ 4
3.1 Regional Geology ................................................................................................ 4
3.2 Site Specific Geology .......................................................................................... 4
3.2.1 Dune Sand (Map symbol Qs) .............................................................................. 4
3.2.2 Quaternary Alluvium (Map Symbol Qal) .............................................................. 4
3.3 Groundwater and Surface Water ........................................................................ 5
3.4 Faulting and Fissuring ......................................................................................... 5
3.5 Ground Shaking .................................................................................................. 5
3.6 Dynamic Settlement (Liquefaction and Dry Settlement) ..................................... 6
3.7 Flooding ............................................................................................................... 7
3.8 Seiche and Tsunami ........................................................................................... 7
3.9 Expansive/Collapsible Soils ................................................................................ 7
3.10 Slope Stability and Landslides ............................................................................ 7
4.0 S U M M A R Y O F F I N D I N G S A N D C O N C L U S I O N S ....................... 8
5.0 R E C O M M E N D A T I O N S ............................................................................... 9
5.1 General ................................................................................................................ 9
5.2 Earthwork Considerations ................................................................................... 9
5.2.1 Site Preparation and Remedial Grading ............................................................. 9
5.2.2 Cut/Fill Transition Lots ....................................................................................... 10
5.2.3 Structural Fills .................................................................................................... 10
5.2.4 Shrinkage and Subsidence................................................................................ 11
5.2.5 Import Soils ........................................................................................................ 11
5.2.6 Utility Trenches .................................................................................................. 11
5.2.7 Drainage ............................................................................................................ 12
5.2.8 Slope Design and Construction ......................................................................... 12
5.3 Foundation Design ............................................................................................ 13
5.3.1 Bearing and Lateral Pressures .......................................................................... 13
5.3.2 Settlement .......................................................................................................... 14
5.3.3 Vapor Retarder .................................................................................................. 14
Preliminary Geotechnical Exploration – Due Diligence August 10, 2022
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5.4 Retaining Walls ................................................................................................. 14
5.5 Geochemical Characteristics ............................................................................ 16
5.6 Preliminary Pavement Design Parameters ....................................................... 16
6.0 GEOTECHNI CAL CO NSTRUCTI ON SERVICES ............................ 18
7.0 LIMITATIONS ................................................................................................ 19
REFERENCES ........................................................................................................ 20
Accompanying Tables, Figures and Appendices (end of text)
Tables
Table 1. 2019 CBC Site-Specific Seismic Coefficients ................................................... 6
Table 2. Retaining Wall Design Earth Pressures (Static, Drained) ............................... 15
Table 3. Preliminary Pavement Design ........................................................................ 16
Figures
Figure 1 – Site Location Map
Figure 2 – Boring Location Plan
Figure 3 – Regional Geology Map
Figure 4 – Regional Fault Map
Appendices
Appendix A – Field Exploration / Geotechnical Borings
Appendix B – Results of Geotechnical Laboratory Testing
Appendix C – General Earthwork and Grading Specifications
Appendix D – GBA Important Information about this Geotechnical Engineering Report
Preliminary Geotechnical Exploration – Due Diligence August 10, 2022
Refuge Palm Desert, Approximately 79 Acre Del Webb Property Project No. 13629.001
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1.0 INTRODUCTION
1.1 Purpose and Scope
This geotechnical report is for the proposed “Del Webb Refuge” project located in
the city of Palm Desert, California (see Figure 1). Our scope of services for this
exploration included the following:
Review of provided previous geotechnical explorations (Petra, 2022) and other
available geologic information and relevant publications listed in the references
at the end of this report.
A site geologic reconnaissance and visual observations of surface conditions.
Excavation, sampling and logging of 7 exploratory geotechnical hollow stem
auger borings throughout the site. Logs of test borings are presented in
Appendix A.
Laboratory testing of representative soil samples obtained from the subsurface
exploration program. A brief description of laboratory testing procedures and
laboratory test results are presented in Appendix B.
Geotechnical engineering analyses performed or as directed by a California
registered Professional Engineer (PE) including preliminary foundation and
seismic design parameters based on the 2019 California Building Code (CBC).
A California Certified Engineering Geologist (CEG) performed engineering
geology review of site geologic hazards.
Preparation of this report which presents the results of our exploration and
provides preliminary geotechnical recommendations for the proposed
residential development. It should be noted that geotechnical reviews and/or
additional subsurface investigation and evaluation may be recommended
based on future site development plans.
This report is not intended to be used as an environmental assessment (Phase I
or other), and foundation and/or a rough grading plan review.
1.2 Site Location and Description
The project site is located on three contiguous undeveloped parcels, totaling
approximately 79-acres, located southwest of Gerald Ford Drive and Portola
Avenue, City of Palm Desert, California. The approximate limits of the site are
shown on the Site Location Map, Figure 1. The property is bounded on the north
by residential development, Riverside County Sheriff Station and Gerald Ford
Preliminary Geotechnical Exploration – Due Diligence August 10, 2022
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Drive, Shadow Ridge Resort and golf course to the west, and existing residences
to the south and the east. The Riverside County Assessor designates the site as
Assessor Parcel Numbers (APNs) 694-310-002, 694-310-003, and portions of
694-310-006.
Topographically, the site and surrounding area slopes to the east and northeast.
Site elevations range from high point elevation of approximately 323 feet above
mean sea level (msl) near the southwestern corner to a low point elevation of
approximately 275 (msl) near the northeast corner of the property. The site is
currently vacant sand dune topography.
1.3 Proposed Development
Based on a provided conceptual plan by MSA Consulting, we understand that the
proposed development will consist of 351 residential units, a 3.3-acre community
center, along with associated site improvements. Details on grading, lot size and
total number of lots are unavailable at this time. We anticipate each lot is to host
a one- or two-story single or multi-family residential homes consisting of typical
wood-frame structure with slab-on-grade foundations. The foundation loads are
not expected to exceed 2,500 pounds per lineal foot (plf) for continuous footings.
We anticipate that site grading will include typical cut and fill grading to create level
pads, access streets and 2:1 slopes. The maximum proposed cut and fill thickness
is unknown at this time but we estimate it could be on the order of 5 to 15 feet. If
site development significantly differs from the assumptions made herein, the
recommendations included in this report should be subject to further review and
evaluation.
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2.0 FIELD EXPLORATION AN D LABORATORY TESTING
2.1 Previous Studies
Petra Geosciences (Petra, 2022) prepared a geotechnical investigation that
included advancing four geotechnical borings to a maximum depth of 66 feet below
ground surface and one percolation test hole to a depth of 10 feet bgs within this
tract. Remedial earthwork recommendations included over-excavation of the
upper 4 feet of surficial soil plus any undocumented fill soils, or 2 feet below
footings, whichever is deeper. Site soils are expected to have a Very Low
Expansion potential.
2.2 Field Exploration
Our field exploration program consisted of 7 hollow-stem auger borings excavated
at the approximate locations shown on the Boring Location Map (Figure 2). During
excavation, bulk samples and relatively “undisturbed” Ring samples were collected
from the exploration borings for further laboratory testing and evaluation. The
relatively undisturbed samples were obtained utilizing a modified California drive
sampler (2⅜-inch inside diameter and 3-inch outside diameter) driven 18 inches in
general accordance with ASTM Test Method D3550. Standard penetration tests
(SPT) were performed using a 2-inch outside diameter (1⅜-inch inside diameter)
sampler driven 18 inches in general accordance with ASTM Test Method D1586.
The number of blows to drive the samplers are recorded on the boring logs for
each 6-inch increment (unless encountering refusal or >50 blows per 6 inches).
Sampling was conducted by a staff geologist from our firm. After logging and
sampling, the excavations were loosely backfilled with spoils generated during
excavation. The logs of exploratory test borings are presented in Appendix A.
2.3 Laboratory Testing
Laboratory tests were performed on representative bulk and undisturbed drive
samples to provide a basis for development of remedial earthwork and
geotechnical design parameters. Selected samples were tested for the following
parameters: insitu moisture and density, maximum dry density (Proctor), R-Value,
gradation, collapse, soluble sulfate, pH, resistivity and chloride content. The
results of our laboratory testing are presented in Appendix B.
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3.0 GEOTECHNICAL AND GEOLOGIC FINDINGS
3.1 Regional Geology
The site is located in the Coachella Valley in the Colorado Desert Geomorphic
Province of California. The San Bernardino Mountains of the Transverse Ranges
Geomorphic Province are to the north and the San Jacinto Mountains of the
Peninsular Range are to the south. The dominant structural feature in this region
is the active San Andreas transform system that consists of several major
northwest-trending right lateral strike slip faults that extend through the San
Gorgonio pass along the southern foothills of the San Bernardino Mountains, and
along the northeast margin of the Coachella Valley. The San Andreas Fault Zone
is composed of a series of fault zones of which the Garnet Hill and south branch
of the San Andreas are located in the immediate site vicinity north of the site.
Figure 3, Regional Geology Map, shows the region as unconsolidated Holocene
sediments (alluvium and other deposits). The site itself is underlain by wind-blown
(aeolian) sand deposits as well as alluvial soil eroded from the nearby mountains
and deposited in the site vicinity.
3.2 Site Specific Geology
Based on the results of our field exploration and review of relevant geologic data
for this area (see References), the site subsurface materials consist of dune sands
over alluvium to the depths explored. These units are discussed in the following
sections in order of increasing age and further described on the logs of
geotechnical borings in Appendix A.
3.2.1 Dune Sand (Map symbol Qs)
Dune sand materials are expected to mantle the majority of the site. The
depth of the dune sand materials cannot be easily verified based on this
limited investigation and relatively homogenous onsite alluvium. However,
it is estimated that the dune sands generally extend to a depth varying from
10 to 20 feet below ground surface (BGS). These materials generally
consist of light brown gray to darker gray and loose to medium dense silty
sand to poorly-graded fine sand. Based on the results of our laboratory
testing, these materials are expected to possess a very low expansion
potential (EI<21) and N-values ranging from 6 to 22 blows/foot.
3.2.2 Quaternary Alluvium (Map Symbol Qal)
Quaternary-aged alluvial deposits were encountered in all of our borings to
the maximum depth explored. As encountered, the alluvium typically
Preliminary Geotechnical Exploration – Due Diligence August 10, 2022
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consists of light brown to brownish gray, medium dense to very dense,
poorly-graded fine sand to sand with silt. The alluvium is expected to
generally possess very low expansion potential (EI<21).
3.3 Groundwater and Surface Water
Groundwater was not encountered in any of the borings and no standing water
was observed on the ground surface during the time of the investigation.
According to Department of water Resources, Southern District, Well
337731N1163848W001 (local well KW_015) located southwest of the site,
groundwater depths may be between 250 and 275 feet below ground surface
(bgs). Based on this data, it appears that shallow groundwater has not been
present recently, or historically. As such, groundwater is not expected to be a
constraint to development of the site. However, it should be noted that local
perched water conditions may exist intermittently and may fluctuate seasonally,
depending on rainfall and irrigation conditions. Surface runoff from the adjacent
elevated portions of the site should be anticipated.
3.4 Faulting and Fissuring
This site is not located within a currently designated Alquist-Priolo Earthquake
Fault Zone or County of Riverside Fault Zone. No active, inactive fault traces or
fissuring are known to traverse the planned development portions (Bryant and Hart
2007) and no evidence of onsite faulting was observed during our investigation.
As defined by the California Geologic Survey, an active fault is one that has had
surface displacement within the Holocene Epoch (roughly the last 11,000 years).
The closest known active fault zones are the San Bernardino Segment of the San
Andreas Fault Zone. The San Bernardino Segment of the San Andreas Fault Zone
is located approximately, 4.5 miles (7.3 km) northwest of the site (Blake, 2000).
The San Gorgonio Pass-Garnet Hill Segment of the San Andreas Fault Zone is
considered to be the source of the design earthquake.
3.5 Ground Shaking
Strong ground shaking can be expected at the site during moderate to severe
earthquakes in this general region. This is common to virtually all of Southern
California. Intensity of ground shaking at a given location depends primarily upon
earthquake magnitude, site distance from the source, and site response (soil type)
characteristics. Based on the 2019 California Building Code (CBC) and using the
Preliminary Geotechnical Exploration – Due Diligence August 10, 2022
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USGS Ground Motion Parameter Calculator, the seismic coefficients for this site
are provided in the following table:
Table 1. 2019 CBC Site-Specific Seismic Coefficients
CBC Categorization/Coefficient Design Value (g)
Site Longitude (-116.37719) Site Latitude (33.78099)
Site Class Definition D
Mapped Spectral Response Acceleration at 0.2s Period, Ss 1.74
Mapped Spectral Response Acceleration at 1s Period, S1 0.72
Short Period Site Coefficient at 0.2s Period, Fa 1.00
Long Period Site Coefficient at 1s Period, Fv 1.70
Adjusted Spectral Response Acceleration at 0.2s Period, SMS 1.74
Adjusted Spectral Response Acceleration at 1s Period, SM1 1.22
Design Spectral Response Acceleration at 0.2s Period, SDS 1.16
Design Spectral Response Acceleration at 1s Period, SD1 0.82
* g- Gravity acceleration
The seismic coefficients for Site Class D follows Exception (2) in Section 11.4.8 of
ASCE 7-16 that assumes a fundamental period of vibration less than 0.5s for the
proposed structures. The project structural engineer should confirm such
assumption or else a site–specific ground motion analysis will be required. Based
on this analysis, the Peak Horizontal Ground Acceleration (PGA) is 0.76g and the
site modified Peak Horizontal Ground Acceleration (PGAm) is 0.83g.
3.6 Dynamic Settlement (Liquefaction and Dry Settlement)
Liquefaction and dynamic settlement of cohesionless soils can be caused by
strong vibratory motion due to earthquakes. Research and historical data indicate
that loose granular soils below a near-surface groundwater table are most
susceptible to liquefaction. Due to the absence of shallow groundwater, the
liquefaction-induced settlement is considered very low on this site.
However, during a strong seismic event, seismically-induced settlement can still
occur within loose to moderately dense, dry or saturated granular soils. Settlement
caused by ground shaking is often non-uniformly distributed, which can result in
differential settlement. Based on the proposed remedial grading recommendations
in areas of planned development, the potential total settlement resulting from
ground shaking is considered minimal or less than 1 inch in the upper 50 feet of
soils.
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3.7 Flooding
The site is not within a flood plain and potential for flooding is considered very low
for this site.
3.8 Seiche and Tsunami
Due to the sites elevated location and lack of nearby open bodies of water, the
possibility of the affects due to seiches or tsunami is considered nil.
3.9 Expansive/Collapsible Soils
Limited laboratory testing indicated that onsite soils possess a very low expansion
potential (EI<21). Based on the remedial grading recommendations in areas of
planned development, the potential impact due to collapsible soils, if they exist
onsite, is considered nil.
3.10 Slope Stability and Landslides
Significant slopes are not located on or near the site. As such, slope instability is
not considered an issue at this site. The site is not considered susceptible to
seismically induced landslides.
Preliminary Geotechnical Exploration – Due Diligence August 10, 2022
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4.0 SUMMARY OF FIND INGS AND CONCLUSIONS
Based on the results of this exploration, it is our opinion that the proposed development
is feasible from a geotechnical/geologic standpoint. The following is a summary of the
main geotechnical findings or factors that may affect development of the site.
The existing onsite soils appear to be suitable for reuse as fill during proposed
grading provided they are relatively free of organic material and debris.
Undocumented fill soils, topsoil, and loose dune sand are considered to be
potentially compressible. These materials should be removed and recompacted
in areas of planned development.
Based on our subsurface explorations, it is our opinion that the onsite earth
materials in most areas can be excavated with heavy-duty conventional grading
equipment in good working condition.
Evidence of active faulting was not identified within the planned development area
of the subject site. Strong ground shaking may occur at this site due to local
earthquake activity.
Perched groundwater was not encountered, however, may develop in areas of
soils with contrasting permeabilities possibly resulting in saturated fills or seepage
from slopes. This condition is often a result of individual homeowners’ water use
and irrigation practices.
Based on preliminary laboratory results and field observations, onsite earth
materials are expected to possess a very low expansion potential and negligible
sulfate exposure to concrete. Additional testing should be performed during site
grading to verify these observations.
Cut slopes greater than 3 feet in height are recommended to be constructed as
replacement fill slopes.
Fill slopes are anticipated to be less than 20 feet in height and are expected to be
grossly and surficially stable.
Unprotected pads and slope faces will be susceptible to erosion. This risk can be
reduced by planting the slopes as soon as possible after grading, and by
maintaining proper erosion control measures
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5.0 RECOMMENDATIONS
5.1 General
Based on the results of this preliminary exploration, it is our opinion that the subject
site is suitable for the proposed development from a geotechnical viewpoint.
Grading of the site should be in accordance with our recommendations included in
this report and future recommendations based on additional site-specific
development plans and evaluations made during construction by the geotechnical
consultant.
5.2 Earthwork Considerations
Earthwork should be performed in accordance with the General Earthwork and
Grading Specifications in Appendix C as well as the following recommendations.
The recommendations contained in Appendix C, are general grading specifications
provided for typical grading projects and some of the recommendations may not
be strictly applicable to this project. The specific recommendations contained in
the text of this report supersede the general recommendations in Appendix C.
The contract between the developer and earthwork contractor should be worded
such that it is the responsibility of the contractor to place the fill properly in
accordance with the recommendations of this report, and applicable County
Grading Ordinances, notwithstanding the testing and observation of the
geotechnical consultant during construction.
5.2.1 Site Preparation and Remedial Grading
Prior to grading, the proposed structural improvement areas (i.e. all structural
fill areas, pavement areas, buildings, etc.) of the site should be cleared of
surface and subsurface obstructions, heavy vegetation and boulders. Roots
and debris should be disposed of offsite. Septic Tanks or seepage pits, if
encountered, should be abandoned in accordance with the County of
Riverside Department of Health Services guidelines.
The near surface soils are potentially compressible in their present state and
may settle under the surcharge of fills or foundation loading. As such, these
materials should be removed (over-excavated) and re-compacted in all
settlement-sensitive areas in accordance with the criteria presented below.
Since these soils are considered potentially compressible in their current in-
situ dry conditions, pre-watering/saturation of these near surface soils is
recommended. It is estimated that with pre-watering to optimum moisture
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condition to depths of 5 to 7 feet below existing grades (in fill areas) the
planned remedial removal depths may be reduced to 3 feet provided the
depth of saturation is determined and/or verified at the time of grading. In
general, the depth of removal should be anticipated to extend 4 feet below
existing grade or 3 feet below street subgrade, pad subgrade or footing
bottom, or whichever is deeper. However, such criteria should be further
verified based on review of future site development plans and foundation
loads:
Acceptability of all removal bottoms should be reviewed by the geotechnical
consultant and documented in the as-graded geotechnical report. The
removal limit should be established by a 1:1 (horizontal: vertical) projection
from the edge of fill soils supporting settlement-sensitive structures
downward and outward to competent material identified by the geotechnical
consultant. Removal will also include benching into competent material as
the fills rise. Areas adjacent to existing structures or property limits may
require special considerations and monitoring. Steeper temporary slopes
in these areas may be considered.
5.2.2 Cut/Fill Transition Lots
In order to mitigate the impact of underlying cut/fill transition conditions, we
recommend over-excavation of the cut portion of transition lots. Over-
excavation should extend to a minimum depth of 3 feet below the bottom of
the proposed footings or one-half of the maximum fill thickness on the lot,
whichever is deeper (not to exceed 10 feet). This overexcavation does not
include scarification or preprocessing prior to placement of fill.
5.2.3 Structural Fills
The onsite soils are generally suitable for re-use as compacted fill provided
they are free of debris and organic matter. Areas to receive structural fill
and/or other surface improvements should be scarified to a minimum depth
of 8 inches, conditioned to at least optimum moisture content, and
recompacted. Fill soils should be placed at a minimum of 90 percent
relative compaction (based on ASTM D1557) and near or above optimum
moisture content. Placement and compaction of fill should be performed in
accordance with local grading ordinances under the observation and testing
of the geotechnical consultant. The optimum lift thickness to produce a
uniformly compacted fill will depend on the type and size of compaction
equipment used. In general, fill should be placed in uniform lifts not
exceeding 8 inches in thickness.
Fill slope keyways will be necessary at the toe of all fill slopes and cut slope
replacement fills. Keyway schematics, including dimensions and subdrain
recommendations, are provided in Appendix D. All keyways should be
excavated into dense bedrock or dense alluvium as determined by the
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geotechnical engineer. The cut portions of all slope and keyway
excavations should be geologically mapped and approved by a geologist
prior to fill placement.
Fills placed on slopes steeper than 5:1 (horizontal:vertical) should be
benched into dense soils (see Appendix D for benching detail). Benching
should be of sufficient depth to remove all loose material. A minimum bench
height of 2 feet into approved material should be maintained at all times.
5.2.4 Shrinkage and Subsidence
The volume change of excavated onsite materials upon compaction is
expected to vary with materials, volume of roots and deleterious materials,
density, insitu moisture content, location, and compaction effort. The in-
place and compacted densities of soil materials vary and accurate overall
determination of shrinkage and bulking cannot be made. Therefore, we
recommend site grading include, if possible, a balance area or ability to
adjust import quantities to accommodate some variation. Based on our
experience with similar materials, we anticipate 12 to 15 percent shrinkage
in the upper 5 to 10 feet of dune sand/alluvium.
Subsidence due solely to scarification, moisture conditioning and
recompaction of the exposed bottom of overexcavation, is expected to be
on the order of 0.10 foot. This should be added to the above shrinkage
value for the recompacted fill zone, to calculate overall recompaction
subsidence.
5.2.5 Import Soils
Import soils and/or borrow sites, if needed, should be evaluated by the
geotechnical consultant prior to import. Import soils should be
uncontaminated, granular in nature, free of organic material (loss on ignition
less-than 2 percent), have a very low expansion potential (with an
Expansion Index less than 21) and have a low corrosion impact to the
proposed improvements.
5.2.6 Utility Trenches
Utility trenches should be backfilled with compacted fill in accordance with
Sections 306-1.2 and 306-1.3 of the Standard Specifications for Public
Works Construction, (“Greenbook”), 2021 Edition (or most recent). Fill
material above the pipe zone should be placed in lifts not exceeding
8 inches in uncompacted thickness and should be compacted to at least 90
percent relative compaction (ASTM D 1557) by mechanical means only.
Site soils may generally be suitable as trench backfill provided these soils
are screened of rocks over 1½ inches in diameter and organic matter. If
imported sand is used as backfill, the upper 3 feet in building and pavement
areas should be compacted to 95 percent. The upper 6 inches of backfill in
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all pavement areas should be compacted to at least 95 percent relative
compaction.
Where granular backfill is used in utility trenches adjacent moisture
sensitive subgrades and foundation soils, we recommend that a cut-off
“plug” of impermeable material be placed in these trenches at the perimeter
of buildings, and at pavement edges adjacent to irrigated landscaped areas.
A “plug” can consist of a 5-foot long section of clayey soils with more than
35-percent passing the No. 200 sieve, or a Controlled Low Strength Material
(CLSM) consisting of one sack of Portland-cement plus one sack of
bentonite per cubic-yard of sand. CLSM should generally conform to
Section 201-6 of the Standard Specifications for Public Works Construction,
(“Greenbook”), 2021 Edition. This is intended to reduce the likelihood of
water permeating trenches from landscaped areas, then seeping along
permeable trench backfill into the building and pavement subgrades,
resulting in wetting of moisture sensitive subgrade earth materials under
buildings and pavements.
Excavation of utility trenches should be performed in accordance with the
project plans, specifications and the California Construction Safety Orders
(Current Edition). The contractor should be responsible for providing a
"competent person" as defined in Article 6 of the California Construction
Safety Orders. Contractors should be advised that sandy soils (such as fills
generated from the onsite alluvium) could make excavations particularly
unsafe if all safety precautions are not properly implemented. In addition,
excavations at or near the toe of slopes and/or parallel to slopes may be
highly unstable due to the increased driving force and load on the trench
wall. Spoil piles from the excavation(s) and construction equipment should
be kept away from the sides of the trenches. Leighton does not consult in
the area of safety engineering.
5.2.7 Drainage
All drainage should be directed away from structures, slopes and
pavements by means of approved permanent/temporary drainage devices.
Adequate storm drainage of any proposed pad should be provided to avoid
wetting of foundation soils. Irrigation adjacent to buildings should be
avoided when possible. As an option, sealed-bottom planter boxes and/or
drought resistant vegetation should be used within 5-feet of buildings.
5.2.8 Slope Design and Construction
Based on our understanding and planning purposes, all fill and cut slopes
will be designed and constructed at 2:1 (horizontal:vertical) with benches at
maximum 30 foot intervals. These slopes are considered grossly stable for
static and pseudostatic conditions. For planning purposes, cut slopes
exceeding 5 feet in height should be constructed as replacement fill slopes
Preliminary Geotechnical Exploration – Due Diligence August 10, 2022
Refuge Palm Desert, Approximately 79 Acre Del Webb Property Project No. 13629.001
13
due to the highly erosive nature of site soils. Future grading plans should
be subject to further review and evaluation.
The outer portion of fill slopes should be either overbuilt by 2 feet (minimum)
and trimmed back to the finished slope configuration or compacted in
vertical increments of 5 feet (maximum) by a weighted sheepsfoot roller as
the fill is placed. The slope face should then be track-walked by dozers of
appropriate weight to achieve the final slope configuration and compaction
to the slope face.
Slope faces are inherently subject to erosion, particularly if exposed to wind,
rainfall and irrigation. Landscaping and slope maintenance should be
conducted as soon as possible in order to increase long-term surficial
stability. Berms should be provided at the top of fill slopes. Drainage should
be directed such that surface runoff on the slope face is minimized
5.3 Foundation Design
5.3.1 Bearing and Lateral Pressures
Based on our analysis, the proposed residential/ and retail/commercial
structures may be founded on conventional foundation systems based on
the design parameters provided below. The proposed foundations and
slabs should be designed in accordance with the structural consultants’
design, the minimum geotechnical recommendations presented herein, and
the 2019 CBC. In utilizing the minimum geotechnical foundation
recommendations, the structural consultant should design the foundation
system to acceptable deflection criteria as determined by the architect.
Foundation footings may be designed with the following geotechnical
design parameters:
Bearing Capacity: A net allowable bearing capacity of 2,000 pounds per
square foot (psf), or a modulus of subgrade reaction of 150 pci may be
used for design of footings founded entirely into compacted fill. The
footings should extend a minimum of 12 inches below lowest adjacent
grade. A minimum base width of 18 inches for continuous footings and
a minimum bearing area of 3 square feet (1.75 ft by 1.75 ft) for pad
foundations should be used. Additionally, an increase of one-third may
be applied when considering short-term live loads (e.g. seismic and
wind).
Passive Pressures: The passive earth pressure may be computed as an
equivalent fluid having a density of 300 psf per foot of depth, to a
maximum earth pressure of 3,000 pounds per square foot. A coefficient
of friction between soil and concrete of 0.35 may be used with dead load
forces. When combining passive pressure and frictional resistance, the
passive pressure component should be reduced by one-third
Preliminary Geotechnical Exploration – Due Diligence August 10, 2022
Refuge Palm Desert, Approximately 79 Acre Del Webb Property Project No. 13629.001
14
The footing width, depth, reinforcement, slab reinforcement, and the slab-
on-grade thickness should be designed by the structural consultant based
on recommendations and soil characteristics indicated herein and the most
recently adopted edition of the CBC.
5.3.2 Settlement
The project civil engineer, structural engineer, and architect should consider
the potential effects of both static settlement and dynamic settlement
presented below.
Static Settlement: Most of the static settlement of onsite soils is expected
to be immediate or within 30 days following fill placement. A differential
static settlement of 0.5 inch over a 40-foot span may be considered for
design purposes. Additional settlement will also occur in the future if
sites grades are raised or due to specific or large footing/foundation
loads.
Dynamic Settlement: Based on our analysis, we estimate that total
dynamic settlement is expected to be less than 1 inch. Differential
settlement is expected to be minimal or less than 0.5 inches over a 40-
foot horizontal span.
5.3.3 Vapor Retarder
It has been a standard of care to install a moisture retarder underneath all
slabs where moisture condensation is undesirable. Moisture vapor retarders
may retard but not totally eliminate moisture vapor movement from the
underlying soils up through the slabs. Moisture vapor transmission may be
additionally reduced by use of concrete additives. Leighton does not practice
in the field of moisture vapor transmission evaluation/mitigation. Therefore,
we recommend that a qualified person/firm be engaged/consulted with to
evaluate the general and specific moisture vapor transmission paths and any
impact on the proposed construction. This person/firm should provide
recommendations for mitigation of potential adverse impact of moisture vapor
transmission on various components of the structure as deemed appropriate.
The slab subgrade soils should be well wetted prior to placing concrete.
5.4 Retaining Walls
Retaining wall earth pressures are a function of the amount of wall yielding
horizontally under load. If the wall can yield enough to mobilize full shear strength
of backfill soils, then the wall can be designed for "active" pressure. If the wall
cannot yield under the applied load, the shear strength of the soil cannot be
mobilized and the earth pressure will be higher. Such walls should be designed
for "at rest" conditions. If a structure moves toward the soils, the resulting
Preliminary Geotechnical Exploration – Due Diligence August 10, 2022
Refuge Palm Desert, Approximately 79 Acre Del Webb Property Project No. 13629.001
15
resistance developed by the soil is the "passive" resistance. Retaining walls
backfilled with non-expansive soils should be designed using the following
equivalent fluid pressures:
Table 2. Retaining Wall Design Earth Pressures (Static, Drained)
Loading
Conditions
Equivalent Fluid Density (pcf)
Active 35 50
At-Rest 50 80
Passive* 300 150 (2:1, sloping down)
* This assumes level condition in front of the wall will remain for the duration of
the project, not to exceed 3,000 psf at depth. If sloping down (2:1) grades exist
in front of walls, then they should be designed using passive values reduced to
½ of level backfill passive resistance values.
Unrestrained (yielding) cantilever walls should be designed for the active
equivalent-fluid weight value provided above for very low to low expansive soils
that are free draining. In the design of walls restrained from movement at the top
(non-yielding) such as basement or elevator pit/utility vaults, the at-rest equivalent
fluid weight value should be used. Total depth of retained earth for design of
cantilever walls should be measured as the vertical distance below the ground
surface measured at the wall face for stem design, or measured at the heel of the
footing for overturning and sliding calculations. Should a sloping backfill other than
a 2:1 (horizontal:vertical) be constructed above the wall (or a backfill is loaded by
an adjacent surcharge load), the equivalent fluid weight values provided above
should be re-evaluated on an individual case basis by us. Non-standard wall
designs should also be reviewed by us prior to construction to check that the proper
soil parameters have been incorporated into the wall design.
All retaining walls should be provided with appropriate drainage. The outlet pipe
should be sloped to drain to a suitable outlet. Typical wall drainage design is
illustrated in Appendix E, Retaining Wall Backfill and Subdrain Detail. Wall backfill
should be non-expansive (EI ≤ 21) sands compacted by mechanical methods to a
minimum of 90 percent relative compaction (ASTM D 1557). Clayey site soils
should not be used as wall backfill. Walls should not be backfilled until wall
concrete attains the 28-day compressive strength and/or as determined by the
Structural Engineer that the wall is structurally capable of supporting backfill.
Lightweight compaction equipment should be used, unless otherwise approved by
the Structural Engineer.
Preliminary Geotechnical Exploration – Due Diligence August 10, 2022
Refuge Palm Desert, Approximately 79 Acre Del Webb Property Project No. 13629.001
16
5.5 Geochemical Characteristics
Limited laboratory testing indicated a negligible concentration of soluble sulfates
in onsite soils for representative samples. The laboratory test results are
presented in Appendix B.
Additional corrosion testing should be performed on representative finish grade
soils at the completion of rough grading. Concrete foundations in contact with site
soils should be designed in accordance with 2019 CBC. A qualified corrosion
engineer should be consulted to review the results of laboratory tests and
coordinate additional testing if corrosion sensitive materials are to be used.
5.6 Preliminary Pavement Design Parameters
In order to provide the following recommendations, we have assumed a R-value
of 65 based on our laboratory testing and the granular nature of the onsite soils
and results of our laboratory testing. For the final pavement design, appropriate
traffic indices should be selected by the project civil engineer or traffic engineering
consultant and representative samples of actual subgrade materials should be
tested for R-value.
Table 3. Preliminary Pavement Design
Street Type
Loading
Conditions
AC Pavement Section Thickness
Asphaltic-Concrete Aggregate Base (AB)
Parking Stalls 5 3.0 4.0
Local Street 6 3.0 6.0
Heavy Traffic 7 4.0 6.0
The subgrade soils in the upper 6 inches should be properly compacted to at least
95 percent relative compaction (ASTM D1557) and should be moisture-
conditioned to near optimum and kept in this condition until the pavement section
is constructed. Proof-rolling subgrade to identify localized areas of yielding
subgrade (if any) should be performed prior to placement of aggregate base and
under the observation of the geotechnical consultant.
Minimum relative compaction requirements for aggregate base should be 95
percent of the maximum laboratory density as determined by ASTM D1557. Base
rock should conform to the "Standard Specifications for Public Works
Construction" (green book) current edition or Caltrans Class 2 aggregate base
having a minimum R-value of 78. Asphaltic concrete should be placed on
Preliminary Geotechnical Exploration – Due Diligence August 10, 2022
Refuge Palm Desert, Approximately 79 Acre Del Webb Property Project No. 13629.001
17
compacted aggregate base and compacted to a minimum 95 percent relative
compaction
The preliminary pavement sections provided in this section are meant as minimum,
if thinner or highly variable pavement sections are constructed, increased
maintenance and repair may be needed.
Preliminary Geotechnical Exploration – Due Diligence August 10, 2022
Refuge Palm Desert, Approximately 79 Acre Del Webb Property Project No. 13629.001
18
6.0 GEOTECHNICAL CONSTRUCTION SERVICES
Geotechnical review is of paramount importance in engineering practice. Poor
performances of many foundation and earthwork projects have been attributed to
inadequate construction review. We recommend that Leighton be provided the
opportunity to review the grading plan and foundation plan(s).
Reasonably-continuous construction observation and review during site grading and
foundation installation allows for evaluation of the actual soil conditions and the ability to
provide appropriate revisions where required during construction. Geotechnical
conclusions and preliminary recommendations should be reviewed and verified by Leighton
during construction, and revised accordingly if geotechnical conditions encountered vary
from our findings and interpretations. Geotechnical observation and testing should be
provided:
After completion of site demolition and clearing,
During ground preparation, fill slope key excavations, overexcavation of surface
soils and subdrain placement as described herein,
During compaction of all fill materials,
After excavation of all footings, and prior to placement of concrete,
During utility trench backfilling and compaction, and
When any unusual conditions are encountered.
Additional geotechnical exploration and analysis may be required based on final
development plans, for reasons such as significant changes in proposed structure
locations/footprints. We should review grading (civil) and foundation (structural) plans, and
comment further on geotechnical aspects of this project.
Preliminary Geotechnical Exploration – Due Diligence August 10, 2022
Refuge Palm Desert, Approximately 79 Acre Del Webb Property Project No. 13629.001
19
7.0 LIMITATIONS
This report was necessarily based in part upon data obtained from a limited number of
observances, site visits, soil samples, tests, analyses, histories of occurrences, spaced
subsurface explorations and limited information on historical events and observations.
Such information is necessarily incomplete. The nature of many sites is such that differing
characteristics can be experienced within small distances and under various climatic
conditions. Changes in subsurface conditions can and do occur over time. This
investigation was performed with the understanding that the subject site is proposed for
residential and commercial development. The client is referred to Appendix D regarding
important information provided by the Associated Soil and Foundation Engineers (ASFE)
on geotechnical engineering studies and reports and their applicability.
This report was prepared for Pulte Home Corp., based on its needs, directions, and
requirements at the time of our investigation. This report is not authorized for use by, and
is not to be relied upon by any party except Pulte Home Corp., and its successors and
assigns as owner of the property, with whom Leighton and Associates, Inc. has
contracted for the work. Use of or reliance on this report by any other party is at that
party's risk. Unauthorized use of or reliance on this report constitutes an agreement to
defend and indemnify Leighton and Associates, Inc. from and against any liability which
may arise as a result of such use or reliance, regardless of any fault, negligence, or strict
liability of Leighton and Associates, Inc.
Preliminary Geotechnical Exploration – Due Diligence August 10, 2022
Refuge Palm Desert, Approximately 79 Acre Del Webb Property Project No. 13629.001
20
REFERENCES
ASCE, 2016, ASCE Standard 7-16, Minimum Design Loads for Buildings and Other
Structures by Structural Engineering Institute, ISBN 0-7844-0809-2, Second
Printing, Published in 2016.
Blake, T. F., 2000a, EQSEARCH, Version 4.00, A Computer Program for the Estimation of
Peak Horizontal Acceleration from Southern California Historical Earthquake
Catalogs, Users Manual, 94pp., with update data, 2006.
Bryant, W. A. and Hart, E. W., 2007, Fault-Rupture Hazard Zones in California, Alquist-Priolo
Earthquake Fault Zoning with Index to Earthquake Zones Maps: Department of
Conservation, California Geologic Survey, Special Publication 42. Interim
Revision.
California Building Code, (CBC) 2019, California Code of Regulations Title 24, Part 2,
Volume 2 of 2.
California Department of Water Resources (CDWR) 2022, Water Data Library,
http://www.water.ca.gov/waterdatalibrary/index.cfm, Data viewed August 10.
California Geologic Survey (CGS), 2012, Landslide Inventory Maps,
www.quake.ca.gov/gmaps/LSIM/lsim_maps.
Civil Tech Corporation, 2005, LIQUEFYPRO Version 5.2, A Computer Program for
Liquefaction and Settlement Analysis, Civil Tech Software, 2005.
Morton, D. M., et al., 1999, Preliminary Digital Geologic Map of the Santa Ana 30’X 60’
Quadrangle, Southern California, Version 1.0, USGS Open-File Report 99-172.
OSHPD, 2022, Seismic Design Maps, an interactive computer program on OSHPD website
to calculate Seismic Response and Design Parameters based on ASCE 7-16
seismic procedures, https://seismicmaps.org/
Petra Geosciences, Inc., 2022, Geotechnical Investigation, Refuge Palm Desert Project,
approximate 93-Acre Site, Assessor’s Parcel Numbers (APNs) 694—310-002
and 694-310-003, southwest of Gerald Ford Drive and Portoa Road, City of
Palm Desert, Riverside County, California, J.N. 22-171, dated June 3, 2022.
Public Works Standard, Inc., 2021, Greenbook, Standard Specifications for Public Works
Construction: BNI Building News, Anaheim, California.
Riverside County, 2003, Riverside County General Plan Safety Element and Appendix H,
Adopted October 7, 2003, Geotechnical Report (Technical Background
Document).
Preliminary Geotechnical Exploration – Due Diligence August 10, 2022
Refuge Palm Desert, Approximately 79 Acre Del Webb Property Project No. 13629.001
21
Riverside County Information Technology, 2022, Map My County (website),
http://mmc.rivcoit.org/MMC_Public/Viewer.html?Viewer=MMC_Public.
United States Geological Survey (USGS), 2000, Cathedral City 7.5-Minute Quadrangle
Topographic Maps. (Printed from TOPO, website, http://www.topo.com).
United States Geological Survey, (USGS), 2006, Geologic Map of the San Bernardino and
Santa Ana 30’x60’ quadrangles, California, Version 1.0, Open File Report 2006-
1217.
Youd, T.L. and I.M. Idriss (Co-Chair), 2001, Liquefaction Resistance of Soils: Summary
Report from the 1996 NCEER and 1998 NCEER/NSF Workshops on Evaluation
of Liquefaction Resistance of Soils, Journal of Geotechnical and
Geoenvironmental Engineering, ASCE, Vol. 127, No. 10, published October
2001.
Scale:
Base Map: Bing Maps 2022
1 " = 2,000 '
Project: 13629.001 Eng/Geol: BSS/RFR
Map Saved as P:\Drafting\13629\001\Maps\13629-001_F01_SLM_2022-08-04.m xd on 8/4/2022 1:17:57 PM
Author: (mmurphy)
Date: August 2022
ApproximateSite Boundary
FIGURE 1SITE LOCATION MAPPulte Del Webb RefugeSouthwest of Gerald Ford Drive and Portola RoadPalm Desert, California
³
0 2,000 4,000
Feet
Base Map: Bing Maps 2022
Map Saved as P:\Drafting\13629\001\Maps\13629-001_F02_BLM_2022-08-04.m xd on 8/4/2022 3:31:00 PM
Author: (mmurphy)
³
1 " = 500 'Scale:
Project: 13629.001 Eng/Geol: BSS/RFR
Date: August 2022
FIGURE 2BORING LOCATION MAPPulte Del Webb RefugeSouthwest of Gerald Ford Drive and Portola RoadPalm Desert, California
0 500 1,000
Feet
Legend
&<Approximate Location of Boring
Approximate Site Boundary
LB-7
!"`$
Qs
Qs
Qs
Qa
Qs
Qs
11 22
33
Scale:
Base Map: Geologic Map of the Thousand Palms andLost Horse Mountain 15 Minute Quadrangles by Thomas W. Dibblee, Jr., 2008.
1 " = 2,000 '
Map Saved as P:\Drafting\13629\001\Maps\13629-001_F03_RGM_2022-08-04.m xd on 8/4/2022 2:51:07 PM
Author: (mmurphy)
Date: August 2022
ApproximateSite Location
Pulte Del Webb RefugeSouthwest of Gerald Ford Drive and Portola RoadPalm Desert, California
³
0 2,000 4,000
Feet
Legend
SURFICIAL SEDIMENTS
Alluvial sand and gravel of valley areas
Loose fine sand deposited by prevailingwinds as dunes
Qa
Qs
Project: 13629.001 Eng/Geol: BSS/RFR FIGURE 3REGIONAL GEOLOGY MAP
³
0 1.5 3
Miles
Scale:
Base Map: ESRI ArcGIS Online 2022Reference: Riverside County Mapping Portal, 9/9/2019.
Map Saved as P:\Drafting\13629\001\Maps\13629-001_F04_RFM _2022-08-04.mxd on 8/4/2022 3:17:11 PM Author: KVM (mm urphy)
Date: August 2022
Approximate Site Location
1 " = 1.5 miles
Legend
Faults
Alquis-Priolo
Riverside County
Fault Zones
Riverside County
Alquist-Priolo
Project: 13629.001 Eng/Geol: BSS/RFR REGIONAL FAULT MAP FIGURE 4
Pulte Del Webb RefugeSouthwest of Gerald Ford Drive and Portola RoadPalm Desert, California
APPENDIX A
FIELD EXPLORATION LOGS OF EXPLORATORY
BORINGS
105
102
SP
SP-SM
B1
R1
R2
R3
R4
R5
0
0
Poorly graded SAND, loose, gray to yellow, dry, medium to coarse
sand,
MD = 113.0 @ 13.0, RV = 69, FINES 4%
No recovery
No recovery
Poorly graded SAND, medium dense, gray, dry, medium to coarse
sand
Poorly graded SAND with Silt, medium dense, grayish brown, moist,
some fines, some mica
-200 = 6
No Recovery
MD, RV,
SA
-200
5
8
12
11
20
23
10
16
25
15
28
44
17
28
55
SIEVE ANALYSIS
SAND EQUIVALENT
SPECIFIC GRAVITY
UNCONFINED COMPRESSIVE
STRENGTH
GEOTECHNICAL BORING LOG LB-1
Hole Diameter
Mo
i
s
t
u
r
e
Ground Elevation
De
p
t
h
Bl
o
w
s
El
e
v
a
t
i
o
n
Pe
r
6
I
n
c
h
e
s
Page 1 of 2
~297'
BULK SAMPLE
CORE SAMPLE
GRAB SAMPLE
RING SAMPLE
SPLIT SPOON SAMPLE
TUBE SAMPLE
B
C
G
R
S
T
MJM
Hollow Stem Auger - 140lb - Autohammer - 30" Drop
So
i
l
C
l
a
s
s
.
7-20-22
SOIL DESCRIPTION
Sampled By
Drilling Co.Drilling Co.
Project
Project No.
See Boring Location Map
Pulte Del Webb Refuge
13629.001
Drilling Method
8"
Sa
m
p
l
e
N
o
.
Fe
e
t
At
t
i
t
u
d
e
s
SAMPLE TYPES:
2R Drilling
* * * This log is a part of a report by Leighton and should not be used as a stand-alone document. * * *
Co
n
t
e
n
t
,
%
Logged By
Date Drilled
MJM
Fe
e
t
S
(U
.
S
.
C
.
S
.
)
Lo
g
Ty
p
e
o
f
T
e
s
t
s
Gr
a
p
h
i
c
pc
f
Location
Dr
y
D
e
n
s
i
t
y
N
This Soil Description applies only to a location of the exploration at the
time of sampling. Subsurface conditions may differ at other locations
and may change with time. The description is a simplification of the
actual conditions encountered. Transitions between soil types may be
gradual.
TYPE OF TESTS:
-200
AL
CN
CO
CR
CU
% FINES PASSING
ATTERBERG LIMITS
CONSOLIDATION
COLLAPSE
CORROSION
UNDRAINED TRIAXIAL
DS
EI
H
MD
PP
RV
DIRECT SHEAR
EXPANSION INDEX
HYDROMETER
MAXIMUM DENSITY
POCKET PENETROMETER
R VALUE
SA
SE
SG
UC
0
5
10
15
20
25
30
SP-SMS6
S7
S8
S9
S10
0.3
0.4
SAND, dense, gray, dry, some fines
-200 = 5
No Recovery
dense, gray, dry, fine sand, some fines, some mica
No recovery
Poorly graded SAND with Silt, very dense, grayish brown, dry, fine
sand, some mica
Total Depth 51.5'
No Groundwater Encountered
Backfilled 7/20/22
-20015
20
28
14
24
33
15
25
33
17
18
21
22
32
37
SIEVE ANALYSIS
SAND EQUIVALENT
SPECIFIC GRAVITY
UNCONFINED COMPRESSIVE
STRENGTH
GEOTECHNICAL BORING LOG LB-1
Hole Diameter
Mo
i
s
t
u
r
e
Ground Elevation
De
p
t
h
Bl
o
w
s
El
e
v
a
t
i
o
n
Pe
r
6
I
n
c
h
e
s
Page 2 of 2
~297'
BULK SAMPLE
CORE SAMPLE
GRAB SAMPLE
RING SAMPLE
SPLIT SPOON SAMPLE
TUBE SAMPLE
B
C
G
R
S
T
MJM
Hollow Stem Auger - 140lb - Autohammer - 30" Drop
So
i
l
C
l
a
s
s
.
7-20-22
SOIL DESCRIPTION
Sampled By
Drilling Co.Drilling Co.
Project
Project No.
See Boring Location Map
Pulte Del Webb Refuge
13629.001
Drilling Method
8"
Sa
m
p
l
e
N
o
.
Fe
e
t
At
t
i
t
u
d
e
s
SAMPLE TYPES:
2R Drilling
* * * This log is a part of a report by Leighton and should not be used as a stand-alone document. * * *
Co
n
t
e
n
t
,
%
Logged By
Date Drilled
MJM
Fe
e
t
S
(U
.
S
.
C
.
S
.
)
Lo
g
Ty
p
e
o
f
T
e
s
t
s
Gr
a
p
h
i
c
pc
f
Location
Dr
y
D
e
n
s
i
t
y
N
This Soil Description applies only to a location of the exploration at the
time of sampling. Subsurface conditions may differ at other locations
and may change with time. The description is a simplification of the
actual conditions encountered. Transitions between soil types may be
gradual.
TYPE OF TESTS:
-200
AL
CN
CO
CR
CU
% FINES PASSING
ATTERBERG LIMITS
CONSOLIDATION
COLLAPSE
CORROSION
UNDRAINED TRIAXIAL
DS
EI
H
MD
PP
RV
DIRECT SHEAR
EXPANSION INDEX
HYDROMETER
MAXIMUM DENSITY
POCKET PENETROMETER
R VALUE
SA
SE
SG
UC
30
35
40
45
50
55
60
99
106
SPR1
R2
R3
R4
0
0
Poorly graded SAND, No recovery
No recovery
Poorly graded SAND, medium dense, gray, dry, coarse sand, some
fines
same as above with some moisture
No recovery, cuttings grayish brown, dense
same as above
Total Depth 21.5'
No Groundwater Encountered
Backfilled 7/20/22
4
5
6
4
9
9
5
10
14
12
18
26
12
24
24
12
20
35
SIEVE ANALYSIS
SAND EQUIVALENT
SPECIFIC GRAVITY
UNCONFINED COMPRESSIVE
STRENGTH
GEOTECHNICAL BORING LOG LB-2
Hole Diameter
Mo
i
s
t
u
r
e
Ground Elevation
De
p
t
h
Bl
o
w
s
El
e
v
a
t
i
o
n
Pe
r
6
I
n
c
h
e
s
Page 1 of 1
~300'
BULK SAMPLE
CORE SAMPLE
GRAB SAMPLE
RING SAMPLE
SPLIT SPOON SAMPLE
TUBE SAMPLE
B
C
G
R
S
T
MJM
Hollow Stem Auger - 140lb - Autohammer - 30" Drop
So
i
l
C
l
a
s
s
.
7-20-22
SOIL DESCRIPTION
Sampled By
Drilling Co.Drilling Co.
Project
Project No.
See Boring Location Map
Pulte Del Webb Refuge
13629.001
Drilling Method
8"
Sa
m
p
l
e
N
o
.
Fe
e
t
At
t
i
t
u
d
e
s
SAMPLE TYPES:
2R Drilling
* * * This log is a part of a report by Leighton and should not be used as a stand-alone document. * * *
Co
n
t
e
n
t
,
%
Logged By
Date Drilled
MJM
Fe
e
t
S
(U
.
S
.
C
.
S
.
)
Lo
g
Ty
p
e
o
f
T
e
s
t
s
Gr
a
p
h
i
c
pc
f
Location
Dr
y
D
e
n
s
i
t
y
N
This Soil Description applies only to a location of the exploration at the
time of sampling. Subsurface conditions may differ at other locations
and may change with time. The description is a simplification of the
actual conditions encountered. Transitions between soil types may be
gradual.
TYPE OF TESTS:
-200
AL
CN
CO
CR
CU
% FINES PASSING
ATTERBERG LIMITS
CONSOLIDATION
COLLAPSE
CORROSION
UNDRAINED TRIAXIAL
DS
EI
H
MD
PP
RV
DIRECT SHEAR
EXPANSION INDEX
HYDROMETER
MAXIMUM DENSITY
POCKET PENETROMETER
R VALUE
SA
SE
SG
UC
0
5
10
15
20
25
30
110
113
SP-SMR1
R2
R3
R4
R5
R6
1
1
Poorly graded SAND with Silt, medium dense, gray, dry, no recovery
No recovery
No recovery
fine to coarse sand
same as above
fine to medium sand, some mica
Total Depth 21.5'
No Groundwater Encountered
Backfilled 7/20/22
6
12
12
6
12
11
8
12
20
10
14
22
14
15
30
14
28
35
SIEVE ANALYSIS
SAND EQUIVALENT
SPECIFIC GRAVITY
UNCONFINED COMPRESSIVE
STRENGTH
GEOTECHNICAL BORING LOG LB-3
Hole Diameter
Mo
i
s
t
u
r
e
Ground Elevation
De
p
t
h
Bl
o
w
s
El
e
v
a
t
i
o
n
Pe
r
6
I
n
c
h
e
s
Page 1 of 1
~305'
BULK SAMPLE
CORE SAMPLE
GRAB SAMPLE
RING SAMPLE
SPLIT SPOON SAMPLE
TUBE SAMPLE
B
C
G
R
S
T
MJM
Hollow Stem Auger - 140lb - Autohammer - 30" Drop
So
i
l
C
l
a
s
s
.
7-20-22
SOIL DESCRIPTION
Sampled By
Drilling Co.Drilling Co.
Project
Project No.
See Boring Location Map
Pulte Del Webb Refuge
13629.001
Drilling Method
8"
Sa
m
p
l
e
N
o
.
Fe
e
t
At
t
i
t
u
d
e
s
SAMPLE TYPES:
2R Drilling
* * * This log is a part of a report by Leighton and should not be used as a stand-alone document. * * *
Co
n
t
e
n
t
,
%
Logged By
Date Drilled
MJM
Fe
e
t
S
(U
.
S
.
C
.
S
.
)
Lo
g
Ty
p
e
o
f
T
e
s
t
s
Gr
a
p
h
i
c
pc
f
Location
Dr
y
D
e
n
s
i
t
y
N
This Soil Description applies only to a location of the exploration at the
time of sampling. Subsurface conditions may differ at other locations
and may change with time. The description is a simplification of the
actual conditions encountered. Transitions between soil types may be
gradual.
TYPE OF TESTS:
-200
AL
CN
CO
CR
CU
% FINES PASSING
ATTERBERG LIMITS
CONSOLIDATION
COLLAPSE
CORROSION
UNDRAINED TRIAXIAL
DS
EI
H
MD
PP
RV
DIRECT SHEAR
EXPANSION INDEX
HYDROMETER
MAXIMUM DENSITY
POCKET PENETROMETER
R VALUE
SA
SE
SG
UC
0
5
10
15
20
25
30
108
99
108
SPR1
B1
R2
R3
R4
R5
0
1
1
No recovery
Poorly graded SAND, loose, gray, dry, fine to coarse sand,
EI = 0
same as above, some mica
same as above
same as above
same as above
Total Depth 16.5'
No Groundwater Encountered
Backfilled 7/20/22
EI, CR
6
6
9
8
12
16
10
14
19
12
20
28
15
18
33
SIEVE ANALYSIS
SAND EQUIVALENT
SPECIFIC GRAVITY
UNCONFINED COMPRESSIVE
STRENGTH
GEOTECHNICAL BORING LOG LB-4
Hole Diameter
Mo
i
s
t
u
r
e
Ground Elevation
De
p
t
h
Bl
o
w
s
El
e
v
a
t
i
o
n
Pe
r
6
I
n
c
h
e
s
Page 1 of 1
~295'
BULK SAMPLE
CORE SAMPLE
GRAB SAMPLE
RING SAMPLE
SPLIT SPOON SAMPLE
TUBE SAMPLE
B
C
G
R
S
T
MJM
Hollow Stem Auger - 140lb - Autohammer - 30" Drop
So
i
l
C
l
a
s
s
.
7-20-22
SOIL DESCRIPTION
Sampled By
Drilling Co.Drilling Co.
Project
Project No.
See Boring Location Map
Pulte Del Webb Refuge
13629.001
Drilling Method
8"
Sa
m
p
l
e
N
o
.
Fe
e
t
At
t
i
t
u
d
e
s
SAMPLE TYPES:
2R Drilling
* * * This log is a part of a report by Leighton and should not be used as a stand-alone document. * * *
Co
n
t
e
n
t
,
%
Logged By
Date Drilled
MJM
Fe
e
t
S
(U
.
S
.
C
.
S
.
)
Lo
g
Ty
p
e
o
f
T
e
s
t
s
Gr
a
p
h
i
c
pc
f
Location
Dr
y
D
e
n
s
i
t
y
N
This Soil Description applies only to a location of the exploration at the
time of sampling. Subsurface conditions may differ at other locations
and may change with time. The description is a simplification of the
actual conditions encountered. Transitions between soil types may be
gradual.
TYPE OF TESTS:
-200
AL
CN
CO
CR
CU
% FINES PASSING
ATTERBERG LIMITS
CONSOLIDATION
COLLAPSE
CORROSION
UNDRAINED TRIAXIAL
DS
EI
H
MD
PP
RV
DIRECT SHEAR
EXPANSION INDEX
HYDROMETER
MAXIMUM DENSITY
POCKET PENETROMETER
R VALUE
SA
SE
SG
UC
0
5
10
15
20
25
30
96
103
112
SP
SP-SM
R1
R2
R3
R4
R5
R6
1
0
0
Poorly graded SAND, medium dense, gray to yellow, dry, medium to
coarse sand
same as above
Poorly graded SAND with Silt, medium dense, gray, moist, mica &
fines
No recovery
SAND with silt, dense, gray, moist, fine to medium sand, some mica
No recovery
Total Depth 21.5'
No Groundwater Encountered
Backfilled 7/20/22
8
9
12
7
9
15
8
12
20
7
8
10
10
15
22
18
14
15
SIEVE ANALYSIS
SAND EQUIVALENT
SPECIFIC GRAVITY
UNCONFINED COMPRESSIVE
STRENGTH
GEOTECHNICAL BORING LOG LB-5
Hole Diameter
Mo
i
s
t
u
r
e
Ground Elevation
De
p
t
h
Bl
o
w
s
El
e
v
a
t
i
o
n
Pe
r
6
I
n
c
h
e
s
Page 1 of 1
~310'
BULK SAMPLE
CORE SAMPLE
GRAB SAMPLE
RING SAMPLE
SPLIT SPOON SAMPLE
TUBE SAMPLE
B
C
G
R
S
T
MJM
Hollow Stem Auger - 140lb - Autohammer - 30" Drop
So
i
l
C
l
a
s
s
.
7-20-22
SOIL DESCRIPTION
Sampled By
Drilling Co.Drilling Co.
Project
Project No.
See Boring Location Map
Pulte Del Webb Refuge
13629.001
Drilling Method
8"
Sa
m
p
l
e
N
o
.
Fe
e
t
At
t
i
t
u
d
e
s
SAMPLE TYPES:
2R Drilling
* * * This log is a part of a report by Leighton and should not be used as a stand-alone document. * * *
Co
n
t
e
n
t
,
%
Logged By
Date Drilled
MJM
Fe
e
t
S
(U
.
S
.
C
.
S
.
)
Lo
g
Ty
p
e
o
f
T
e
s
t
s
Gr
a
p
h
i
c
pc
f
Location
Dr
y
D
e
n
s
i
t
y
N
This Soil Description applies only to a location of the exploration at the
time of sampling. Subsurface conditions may differ at other locations
and may change with time. The description is a simplification of the
actual conditions encountered. Transitions between soil types may be
gradual.
TYPE OF TESTS:
-200
AL
CN
CO
CR
CU
% FINES PASSING
ATTERBERG LIMITS
CONSOLIDATION
COLLAPSE
CORROSION
UNDRAINED TRIAXIAL
DS
EI
H
MD
PP
RV
DIRECT SHEAR
EXPANSION INDEX
HYDROMETER
MAXIMUM DENSITY
POCKET PENETROMETER
R VALUE
SA
SE
SG
UC
0
5
10
15
20
25
30
103
96
109
SP-SMR1
R2
R3
R4
R5
0
0
0
Poorly graded SAND with Silt, loose, gray to yellow, No recovery
Poorly graded SAND with Silt, medium dense, gray, dry, fine to
medium sand, some mica
moist, some mica
fine to coarse sand, lots of mica
same as above
Total Depth 16.5'
No Groundwater Encountered
Backfilled 7/20/22
4
4
6
7
12
15
6
9
12
6
12
18
15
25
32
SIEVE ANALYSIS
SAND EQUIVALENT
SPECIFIC GRAVITY
UNCONFINED COMPRESSIVE
STRENGTH
GEOTECHNICAL BORING LOG LB-6
Hole Diameter
Mo
i
s
t
u
r
e
Ground Elevation
De
p
t
h
Bl
o
w
s
El
e
v
a
t
i
o
n
Pe
r
6
I
n
c
h
e
s
Page 1 of 1
~295'
BULK SAMPLE
CORE SAMPLE
GRAB SAMPLE
RING SAMPLE
SPLIT SPOON SAMPLE
TUBE SAMPLE
B
C
G
R
S
T
MJM
Hollow Stem Auger - 140lb - Autohammer - 30" Drop
So
i
l
C
l
a
s
s
.
7-20-22
SOIL DESCRIPTION
Sampled By
Drilling Co.Drilling Co.
Project
Project No.
See Boring Location Map
Pulte Del Webb Refuge
13629.001
Drilling Method
8"
Sa
m
p
l
e
N
o
.
Fe
e
t
At
t
i
t
u
d
e
s
SAMPLE TYPES:
2R Drilling
* * * This log is a part of a report by Leighton and should not be used as a stand-alone document. * * *
Co
n
t
e
n
t
,
%
Logged By
Date Drilled
MJM
Fe
e
t
S
(U
.
S
.
C
.
S
.
)
Lo
g
Ty
p
e
o
f
T
e
s
t
s
Gr
a
p
h
i
c
pc
f
Location
Dr
y
D
e
n
s
i
t
y
N
This Soil Description applies only to a location of the exploration at the
time of sampling. Subsurface conditions may differ at other locations
and may change with time. The description is a simplification of the
actual conditions encountered. Transitions between soil types may be
gradual.
TYPE OF TESTS:
-200
AL
CN
CO
CR
CU
% FINES PASSING
ATTERBERG LIMITS
CONSOLIDATION
COLLAPSE
CORROSION
UNDRAINED TRIAXIAL
DS
EI
H
MD
PP
RV
DIRECT SHEAR
EXPANSION INDEX
HYDROMETER
MAXIMUM DENSITY
POCKET PENETROMETER
R VALUE
SA
SE
SG
UC
0
5
10
15
20
25
30
121
95
SP-SM
SP
B1
R1
R2
R3
R4
R5
R6
1
1
Poorly graded SAND with Silt, loose, gray, dry, fine sand,
MD = 112.9 @ 12.5
No recovery
No recovery
Poorly graded SAND with silt, medium dense, gray, dry, fine to
medium sand
moist, some mica
Poorly-graded SAND, dense, gray, moist, fine to
medium sand, -200 = 4
No recovery
Total Depth 21.5'
No Groundwater Encountered
Backfilled 7/20/22
MD, CR
-200
5
7
8
9
6
10
7
14
16
7
11
14
12
18
22
7
17
28
SIEVE ANALYSIS
SAND EQUIVALENT
SPECIFIC GRAVITY
UNCONFINED COMPRESSIVE
STRENGTH
GEOTECHNICAL BORING LOG LB-7
Hole Diameter
Mo
i
s
t
u
r
e
Ground Elevation
De
p
t
h
Bl
o
w
s
El
e
v
a
t
i
o
n
Pe
r
6
I
n
c
h
e
s
Page 1 of 1
~295'
BULK SAMPLE
CORE SAMPLE
GRAB SAMPLE
RING SAMPLE
SPLIT SPOON SAMPLE
TUBE SAMPLE
B
C
G
R
S
T
MJM
Hollow Stem Auger - 140lb - Autohammer - 30" Drop
So
i
l
C
l
a
s
s
.
7-20-22
SOIL DESCRIPTION
Sampled By
Drilling Co.Drilling Co.
Project
Project No.
See Boring Location Map
Pulte Del Webb Refuge
13629.001
Drilling Method
8"
Sa
m
p
l
e
N
o
.
Fe
e
t
At
t
i
t
u
d
e
s
SAMPLE TYPES:
2R Drilling
** * This log is a part of a report by Leighton and should not be used as a stand-alone document. * * *
Co
n
t
e
n
t
,
%
Logged By
Date Drilled
MJM
Fe
e
t
S
(U
.
S
.
C
.
S
.
)
Lo
g
Ty
p
e
o
f
T
e
s
t
s
Gr
a
p
h
i
c
pc
f
Location
Dr
y
D
e
n
s
i
t
y
N
This Soil Description applies only to a location of the exploration at the
time of sampling. Subsurface conditions may differ at other locations
and may change with time. The description is a simplification of the
actual conditions encountered. Transitions between soil types may be
gradual.
TYPE OF TESTS:
-200
AL
CN
CO
CR
CU
% FINES PASSING
ATTERBERG LIMITS
CONSOLIDATION
COLLAPSE
CORROSION
UNDRAINED TRIAXIAL
DS
EI
H
MD
PP
RV
DIRECT SHEAR
EXPANSION INDEX
HYDROMETER
MAXIMUM DENSITY
POCKET PENETROMETER
R VALUE
SA
SE
SG
UC
0
5
10
15
20
25
30
APPENDIX B
RESULTS OF GEOTECHNICAL LABORATORY TESTI NG
3.0" 1 1/2" 3/4" 3/8" #4 #8 #16 #30 #50 #100 #200
U.S. STANDARD SIEVE OPENING U.S. STANDARD SIEVE NUMBER
GRAVEL FINES
FINE CLAY COARSE COARSE MEDIUM
13629.001
SAND
SILT FINE
HYDROMETER
Pulte Del Webb Refuge Geo
Project No.:LB-1 Sample No.:
Soil Type :
PARTICLE - SIZE
DISTRIBUTION
ASTM D 6913
Soil Identification:Poorly Graded Sand (SP), Grayish Brown.
SP
GR:SA:FI : (%)
Boring No.:
Depth (feet):0 - 5.0
Project Name:B-1
Aug-220:96 :4
0
10
20
30
40
50
60
70
80
90
100
0.0010.0100.1001.00010.000100.000
PE
R
C
E
N
T
F
I
N
E
R
B
Y
W
E
I
G
H
T
PARTICLE -SIZE (mm)
"
Sieve; LB-1, B-1 (07-23-22)
200 Wash (07-23-22)
LB-1 LB-1 LB-7
R-4 S-6 R-5
20.0 30.0 15.0
RING SPT RING
10 10 10
470.6 984.1 543.8
470.6 983.2 543.8
326.1 699.7 327.7
0.0 0.3 0.0
B 123 K
470.6 983.2 543.8
326.1 699.7 327.7
144.5 283.5 216.1
B 123 K
461.9 970.0 534.8
326.1 699.7 327.7
135.8 270.3 207.1
6 5 4
94 95 96
Project Name:
Project No.:
Client Name:
Tested By:F. Mina Date:08/04/22
SP-SM
PERCENT PASSING
No. 200 SIEVE
ASTM D 1140
SP-SM SP
After Wash
% Retained No. 200 Sieve
% Passing No. 200 Sieve
Sample Dry Weight Determination
Moisture Correction
Soil Classification
Soak Time (min)
Compaction; LB-1, B-1 (07-23-22)
Tested By:F. Mina Date:08/05/22
Input By: M. Vinet Date:08/08/22
LB-1 Depth (ft.):0 - 5.0
X Moist Mechanical Ram
Dry Manual Ram
Mold Volume (ft³)0.03340 Ram Weight = 10 lb.; Drop = 18 in.
1 2 3 4 5 6
5312 5401 5471 5489
3532 3532 3532 3532
1780 1869 1939 1957
1222.6 1252.2 1289.2 1202.3
1158.4 1162.4 1170.9 1073.6
278.2 277.8 280.1 278.2
7.3 10.2 13.3 16.2
117.5 123.4 128.0 129.2
109.5 112.0 113.0 111.2
113.0 13.0
PROCEDURE USED
X Procedure A
Procedure B
Procedure C
Particle-Size Distribution:0:96:4
Atterberg Limits:
MODIFIED PROCTOR COMPACTION TEST
ASTM D 1557
Optimum Moisture Content (%) Maximum Dry Density (pcf)
100.0
105.0
110.0
115.0
120.0
5.0 10.0 15.0 20.0
Dr
y
D
e
n
s
i
t
y
(
p
c
f
)
Moisture Content (%)
SP. GR. = 2.65
SP. GR. = 2.70
XX
Compaction; LB-7, B-1 (07-23-22)
Tested By:F. Mina Date:08/05/22
Input By: M. Vinet Date:08/08/22
LB-7 Depth (ft.):0 - 5.0
X Moist Mechanical Ram
Dry Manual Ram
Mold Volume (ft³)0.03340 Ram Weight = 10 lb.; Drop = 18 in.
1 2 3 4 5 6
5290 5392 5462 5441
3532 3532 3532 3532
1758 1860 1930 1909
1250.2 1302.1 1059.3 1156.2
1185.2 1208.2 969.4 1034.2
276.8 280.4 277.6 278.2
7.2 10.1 13.0 16.1
116.0 122.8 127.4 126.0
108.3 111.5 112.7 108.5
112.9 12.5
PROCEDURE USED
X Procedure A
Procedure B
Procedure C
Particle-Size Distribution:
Atterberg Limits:
Optimum Moisture Content (%) Maximum Dry Density (pcf)
MODIFIED PROCTOR COMPACTION TEST
ASTM D 1557
100.0
105.0
110.0
115.0
120.0
5.0 10.0 15.0 20.0
Dr
y
D
e
n
s
i
t
y
(
p
c
f
)
Moisture Content (%)
SP. GR. = 2.65
SP. GR. = 2.70
XX
Project Name:Date:8/5/22
Project Number:13629.001 Technician:F. Mina
Boring Number:LB-1 Depth (ft.):0 - 5.0
Sample Number:B-1
Sample Description:
TEST SPECIMEN A B C
MOISTURE AT COMPACTION %10.3 11.3 12.3
HEIGHT OF SAMPLE, Inches 2.55 2.48 2.52
DRY DENSITY, pcf 103.6 103.8 104.8
COMPACTOR AIR PRESSURE, psi 350 350 350
EXUDATION PRESSURE, psi 513 326 171
EXPANSION, Inches x 10exp-4 0 0 0
STABILITY Ph 2,000 lbs (160 psi)20 29 36
TURNS DISPLACEMENT 4.67 4.75 4.96
R-VALUE UNCORRECTED 79 70 63
R-VALUE CORRECTED 79 70 63
DESIGN CALCULATION DATA a b c
GRAVEL EQUIVALENT FACTOR 1.0 1.0 1.0
TRAFFIC INDEX 5.0 5.0 5.0
STABILOMETER THICKNESS, ft.0.34 0.47 0.58
EXPANSION PRESSURE THICKNESS, ft.0.00 0.00 0.00
EXPANSION PRESSURE CHART EXUDATION PRESSURE CHART
R-VALUE BY EXPANSION:N/A
R-VALUE BY EXUDATION:69
EQUILIBRIUM R-VALUE:69
R-VALUE TEST RESULTS
ASTM D 2844
0.00
0.50
1.00
1.50
2.00
2.50
3.00
3.50
4.00
0.00 0.50 1.00 1.50 2.00 2.50 3.00 3.50 4.00
CO
V
E
R
T
H
I
C
K
N
E
S
S
B
Y
E
X
P
A
N
S
I
O
N
i
n
fe
e
t
COVER THICKNESS BY STABILOMETER in
feet
0
10
20
30
40
50
60
70
80
90
0100200300400500600700800
R-VA
L
U
E
EXUDATION PRESSURE (psi)
Project Name:Tested By:M. Vinet Date:8/4/22
Project No. :Checked By:M. Vinet Date:8/8/22
Boring No.:Depth:2.0 - 6.0
Sample No. :Location:
Sample Description:
Wt. of Container No. (gm.)
Dry Wt. of Soil (gm.)
Percent Passing # 4
in distilled water for the period of 24 h or expansion rate < 0.0002 in./h.
Rev. 03-08
SPECIMEN INUNDATION
(min.)(in.)
72.850.9
(psi)
EXPANSION INDEX of SOILS
MOLDED SPECIMEN
4.01
1.0000
7Container No.
Specimen Diameter (in.)
Wt. Comp. Soil + Mold (gm.)
200.0
N/A
Pulte Del Webb Refuge Geo
13629.001
LB-4
B-1
100.0
4.01
2.70
1212.6
0.0
582.5
1212.6
0.0
0.9991
600.0
After TestBefore Test
Date Time
0 Expansion Index ( Report ) =
Expansion Index (EI meas) =((Final Rdg - Initial Rdg) / Initial Thick.) x 1000 -0.9
Project Name:Pulte Del Webb Refuge Geo Tested By :F. Mina Date:08/05/22
Project No. :13629.001 Data Input By:M. Vinet Date:08/08/22
Boring No.LB-4 LB-7
Sample No.B-1 B-1
Sample Depth (ft)2.0 - 6.0 0 - 5.0
100.00 100.00
100.00 100.00
0.00 0.00
0.00 0.00
100.00 100.00
1 2
1 2
850 850
Timer Timer
45 45
25.0392 24.8950
25.0361 24.8921
0.0031 0.0029
127.56 119.34
128 119
ml of Extract For Titration (B)30
ml of AgNO3 Soln. Used in Titration (C)1.0
PPM of Chloride (C -0.2) * 100 * 30 / B 80
PPM of Chloride, Dry Wt. Basis 80
8.20
21.0
pH TEST, DOT California Test 643
TESTS for SULFATE CONTENT
CHLORIDE CONTENT and pH of SOILS
SULFATE CONTENT, DOT California Test 417, Part II
Soil Identification:
Moisture Content (%)
Temperature °C
pH Value
Poorly Graded
Sand (SP)
Wt. of Crucible + Residue (g)
Dry Weight of Soil + Container (g)
Weight of Container (g)
Duration of Combustion (min)
Poorly Graded
Sand (SP)
Wet Weight of Soil + Container (g)
Wt. of Residue (g) (A)
Beaker No.
Crucible No.
Furnace Temperature (°C)
Time In / Time Out
Weight of Soaked Soil (g)
PPM of Sulfate, Dry Weight Basis
PPM of Sulfate (A) x 41150
CHLORIDE CONTENT, DOT California Test 422
Wt. of Crucible (g)
Project Name:Tested By :F. Mina Date:
Project No. :Data Input By:M. Vinet Date:
Boring No.:Depth (ft.) :
Sample No. :
Soil Identification:*
*California Test 643 requires soil specimens to consist only of portions of samples passing through the No. 8 US Standard Sieve before resistivity
testing. Therefore, this test method may not be representative for coarser materials.
Wt. of Container (g)10.00 34000
0.00
100.00
Moisture Content (%) (MCi)
Wet Wt. of Soil + Cont. (g)Specimen
No.
1
2
Water
Added (ml)
(Wa)
50
Adjusted
Moisture
Content
(MC)Dry Wt. of Soil + Cont. (g)
34000
1.000
Chloride Content
(ohm-cm)
Moisture Content Sulfate Content
5
Min. Resistivity
DOT CA Test 643DOT CA Test 417 Part II DOT CA Test 422
(%)(ppm)(ppm)
DOT CA Test 643
4
83
116
A
500.0032100023.20
19000
18200 18.0 128 80 8.20 21.0
SOIL RESISTIVITY TEST
DOT CA TEST 643
Temp. (°C)pH
Soil pH
19000
21000
100.00
0.00
MC =(((1+Mci/100)x(Wa/Wt+1))-1)x100
Pulte Del Webb Refuge Geo 08/05/22
08/08/22
2.0 - 6.0
13629.001
LB-4
B-1
Container No.
Initial Soil Wt. (g) (Wt)
Box Constant
Poorly Graded Sand (SP)
Resistance
Reading
(ohm)
16.60
Soil
Resistivity
(ohm-cm)
0
5000
10000
15000
20000
25000
30000
35000
40000
0.0 5.0 10.0 15.0 20.0 25.0
So
i
l
R
e
s
i
s
t
i
v
i
t
y
(
o
h
m
-cm
)
Moisture Content (%)
Minimum resistivity
read here
APPENDIX C
EARTHWORK AND GRADING SPECIFICATIONS
-i-
LEIGHTON AND ASSOCIATES, INC.
GENERAL EARTHWORK AND GRADING SPECIFICATIONS FOR ROUGH GRADING
TABLE OF CONTENTS
Section Page
1.0 GENERAL 1
1.1 Intent 1
1.2 The Geotechnical Consultant of Record 1
1.3 The Earthwork Contractor 2
2.0 PREPARATION OF AREAS TO BE FILLED 2
2.1 Clearing and Grubbing 2
2.2 Processing 3
2.3 Overexcavation 3
2.4 Benching 3
2.5 Evaluation/Acceptance of Fill Areas 3
3.0 FILL MATERIAL 4
3.1 General 4
3.2 Oversize 4
3.3 Import 4
4.0 FILL PLACEMENT AND COMPACTION 4
4.1 Fill Layers 4
4.2 Fill Moisture Conditioning 5
4.3 Compaction of Fill 5
4.4 Compaction of Fill Slopes 5
4.5 Compaction Testing 5
4.6 Frequency of Compaction Testing 5
4.7 Compaction Test Locations 6
5.0 SUBDRAIN INSTALLATION 6
6.0 EXCAVATION 6
7.0 TRENCH BACKFILLS 6
7.1 Safety 6
7.2 Bedding & Backfill 7
7.3 Lift Thickness 7
7.4 Observation and Testing 7
Standard Details
A - Keying and Benching Rear of Text
B - Oversize Rock Disposal Rear of Text
C - Canyon Subdrains Rear of Text
D - Buttress or Replacement Fill Subdrains Rear of Text
E - Transition Lot Fills and Side Hill Fills Rear of Text
Retaining Wall Rear of Text
LEIGHTON AND ASSOCIATES, INC.
General Earthwork and Grading Specifications
-1-
1.0 General
1.1 Intent
These General Earthwork and Grading Specifications are for the grading and
earthwork shown on the approved grading plan(s) and/or indicated in the
geotechnical report(s). These Specifications are a part of the recommendations
contained in the geotechnical report(s). In case of conflict, the specific
recommendations in the geotechnical report shall supersede these more general
Specifications. Observations of the earthwork by the project Geotechnical
Consultant during the course of grading may result in new or revised
recommendations that could supersede these specifications or the
recommendations in the geotechnical report(s).
1.2 The Geotechnical Consultant of Record
Prior to commencement of work, the owner shall employ the Geotechnical
Consultant of Record (Geotechnical Consultant). The Geotechnical Consultants
shall be responsible for reviewing the approved geotechnical report(s) and
accepting the adequacy of the preliminary geotechnical findings, conclusions, and
recommendations prior to the commencement of the grading.
Prior to commencement of grading, the Geotechnical Consultant shall review the
"work plan" prepared by the Earthwork Contractor (Contractor) and schedule
sufficient personnel to perform the appropriate level of observation, mapping, and
compaction testing.
During the grading and earthwork operations, the Geotechnical Consultant shall
observe, map, and document the subsurface exposures to verify the geotechnical
design assumptions. If the observed conditions are found to be significantly
different than the interpreted assumptions during the design phase, the
Geotechnical Consultant shall inform the owner, recommend appropriate changes
in design to accommodate the observed conditions, and notify the review agency
where required. Subsurface areas to be geotechnically observed, mapped,
elevations recorded, and/or tested include natural ground after it has been cleared
for receiving fill but before fill is placed, bottoms of all "remedial removal" areas,
all key bottoms, and benches made on sloping ground to receive fill.
The Geotechnical Consultant shall observe the moisture-conditioning and
processing of the subgrade and fill materials and perform relative compaction
testing of fill to determine the attained level of compaction. The Geotechnical
Consultant shall provide the test results to the owner and the Contractor on a
routine and frequent basis.
LEIGHTON AND ASSOCIATES, INC.
General Earthwork and Grading Specifications
-2-
1.3 The Earthwork Contractor
The Earthwork Contractor (Contractor) shall be qualified, experienced, and
knowledgeable in earthwork logistics, preparation and processing of ground to
receive fill, moisture-conditioning and processing of fill, and compacting fill. The
Contractor shall review and accept the plans, geotechnical report(s), and these
Specifications prior to commencement of grading. The Contractor shall be solely
responsible for performing the grading in accordance with the plans and
specifications.
The Contractor shall prepare and submit to the owner and the Geotechnical
Consultant a work plan that indicates the sequence of earthwork grading, the
number of "spreads" of work and the estimated quantities of daily earthwork
contemplated for the site prior to commencement of grading. The Contractor
shall inform the owner and the Geotechnical Consultant of changes in work
schedules and updates to the work plan at least 24 hours in advance of such
changes so that appropriate observations and tests can be planned and
accomplished. The Contractor shall not assume that the Geotechnical Consultant
is aware of all grading operations.
The Contractor shall have the sole responsibility to provide adequate equipment
and methods to accomplish the earthwork in accordance with the applicable
grading codes and agency ordinances, these Specifications, and the
recommendations in the approved geotechnical report(s) and grading plan(s). If,
in the opinion of the Geotechnical Consultant, unsatisfactory conditions, such as
unsuitable soil, improper moisture condition, inadequate compaction, insufficient
buttress key size, adverse weather, etc., are resulting in a quality of work less than
required in these specifications, the Geotechnical Consultant shall reject the work
and may recommend to the owner that construction be stopped until the
conditions are rectified.
2.0 Preparation of Areas to be Filled
2.1 Clearing and Grubbing
Vegetation, such as brush, grass, roots, and other deleterious material shall be
sufficiently removed and properly disposed of in a method acceptable to the
owner, governing agencies, and the Geotechnical Consultant.
The Geotechnical Consultant shall evaluate the extent of these removals
depending on specific site conditions. Earth fill material shall not contain more
than 1 percent of organic materials (by volume). No fill lift shall contain more
than 5 percent of organic matter. Nesting of the organic materials shall not be
allowed.
LEIGHTON AND ASSOCIATES, INC.
General Earthwork and Grading Specifications
-3-
If potentially hazardous materials are encountered, the Contractor shall stop work
in the affected area, and a hazardous material specialist shall be informed
immediately for proper evaluation and handling of these materials prior to
continuing to work in that area.
As presently defined by the State of California, most refined petroleum products
(gasoline, diesel fuel, motor oil, grease, coolant, etc.) have chemical constituents
that are considered to be hazardous waste. As such, the indiscriminate dumping
or spillage of these fluids onto the ground may constitute a misdemeanor,
punishable by fines and/or imprisonment, and shall not be allowed.
2.2 Processing
Existing ground that has been declared satisfactory for support of fill by the
Geotechnical Consultant shall be scarified to a minimum depth of 6 inches.
Existing ground that is not satisfactory shall be overexcavated as specified in the
following section. Scarification shall continue until soils are broken down and
free of large clay lumps or clods and the working surface is reasonably uniform,
flat, and free of uneven features that would inhibit uniform compaction.
2.3 Overexcavation
In addition to removals and overexcavations recommended in the approved
geotechnical report(s) and the grading plan, soft, loose, dry, saturated, spongy,
organic-rich, highly fractured or otherwise unsuitable ground shall be
overexcavated to competent ground as evaluated by the Geotechnical Consultant
during grading.
2.4 Benching
Where fills are to be placed on ground with slopes steeper than 5:1 (horizontal to
vertical units), the ground shall be stepped or benched. The lowest bench or key
shall be a minimum of 15 feet wide and at least 2 feet deep, into competent
material as evaluated by the Geotechnical Consultant. Other benches shall be
excavated a minimum height of 4 feet into competent material or as otherwise
recommended by the Geotechnical Consultant. Fill placed on ground sloping
flatter than 5:1 shall also be benched or otherwise overexcavated to provide a flat
subgrade for the fill.
2.5 Evaluation/Acceptance of Fill Areas
All areas to receive fill, including removal and processed areas, key bottoms, and
benches, shall be observed, mapped, elevations recorded, and/or tested prior to
being accepted by the Geotechnical Consultant as suitable to receive fill. The
Contractor shall obtain a written acceptance from the Geotechnical Consultant
LEIGHTON AND ASSOCIATES, INC.
General Earthwork and Grading Specifications
-4-
prior to fill placement. A licensed surveyor shall provide the survey control for
determining elevations of processed areas, keys, and benches.
3.0 Fill Material
3.1 General
Material to be used as fill shall be essentially free of organic matter and other
deleterious substances evaluated and accepted by the Geotechnical Consultant
prior to placement. Soils of poor quality, such as those with unacceptable
gradation, high expansion potential, or low strength shall be placed in areas
acceptable to the Geotechnical Consultant or mixed with other soils to achieve
satisfactory fill material.
3.2 Oversize
Oversize material defined as rock, or other irreducible material with a maximum
dimension greater than 8 inches, shall not be buried or placed in fill unless
location, materials, and placement methods are specifically accepted by the
Geotechnical Consultant. Placement operations shall be such that nesting of
oversized material does not occur and such that oversize material is completely
surrounded by compacted or densified fill. Oversize material shall not be placed
within 10 vertical feet of finish grade or within 2 feet of future utilities or
underground construction.
3.3 Import
If importing of fill material is required for grading, proposed import material shall
meet the requirements of Section 3.1. The potential import source shall be given
to the Geotechnical Consultant at least 48 hours (2 working days) before
importing begins so that its suitability can be determined and appropriate tests
performed.
4.0 Fill Placement and Compaction
4.1 Fill Layers
Approved fill material shall be placed in areas prepared to receive fill (per
Section 3.0) in near-horizontal layers not exceeding 8 inches in loose thickness.
The Geotechnical Consultant may accept thicker layers if testing indicates the
grading procedures can adequately compact the thicker layers. Each layer shall be
spread evenly and mixed thoroughly to attain relative uniformity of material and
moisture throughout.
LEIGHTON AND ASSOCIATES, INC.
General Earthwork and Grading Specifications
-5-
4.2 Fill Moisture Conditioning
Fill soils shall be watered, dried back, blended, and/or mixed, as necessary to
attain a relatively uniform moisture content at or slightly over optimum.
Maximum density and optimum soil moisture content tests shall be performed in
accordance with the American Society of Testing and Materials (ASTM Test
Method D1557).
4.3 Compaction of Fill
After each layer has been moisture-conditioned, mixed, and evenly spread, it shall
be uniformly compacted to not less than 90 percent of maximum dry density
(ASTM Test Method D1557). Compaction equipment shall be adequately sized
and be either specifically designed for soil compaction or of proven reliability to
efficiently achieve the specified level of compaction with uniformity.
4.4 Compaction of Fill Slopes
In addition to normal compaction procedures specified above, compaction of
slopes shall be accomplished by backrolling of slopes with sheepsfoot rollers at
increments of 3 to 4 feet in fill elevation, or by other methods producing
satisfactory results acceptable to the Geotechnical Consultant. Upon completion
of grading, relative compaction of the fill, out to the slope face, shall be at least
90 percent of maximum density per ASTM Test Method D1557.
4.5 Compaction Testing
Field-tests for moisture content and relative compaction of the fill soils shall be
performed by the Geotechnical Consultant. Location and frequency of tests shall
be at the Consultant's discretion based on field conditions encountered.
Compaction test locations will not necessarily be selected on a random basis. Test
locations shall be selected to verify adequacy of compaction levels in areas that
are judged to be prone to inadequate compaction (such as close to slope faces and
at the fill/bedrock benches).
4.6 Frequency of Compaction Testing
Tests shall be taken at intervals not exceeding 2 feet in vertical rise and/or
1,000 cubic yards of compacted fill soils embankment. In addition, as a guideline,
at least one test shall be taken on slope faces for each 5,000 square feet of slope
face and/or each 10 feet of vertical height of slope. The Contractor shall assure
that fill construction is such that the testing schedule can be accomplished by the
Geotechnical Consultant. The Contractor shall stop or slow down the earthwork
construction if these minimum standards are not met.
LEIGHTON AND ASSOCIATES, INC.
General Earthwork and Grading Specifications
-6-
4.7 Compaction Test Locations
The Geotechnical Consultant shall document the approximate elevation and
horizontal coordinates of each test location. The Contractor shall coordinate with
the project surveyor to assure that sufficient grade stakes are established so that
the Geotechnical Consultant can determine the test locations with sufficient
accuracy. At a minimum, two grade stakes within a horizontal distance of 100
feet and vertically less than 5 feet apart from potential test locations shall be
provided.
5.0 Subdrain Installation
Subdrain systems shall be installed in accordance with the approved geotechnical
report(s), the grading plan. The Geotechnical Consultant may recommend additional
subdrains and/or changes in subdrain extent, location, grade, or material depending on
conditions encountered during grading. All subdrains shall be surveyed by a land
surveyor/civil engineer for line and grade after installation and prior to burial. Sufficient
time should be allowed by the Contractor for these surveys.
6.0 Excavation
Excavations, as well as over-excavation for remedial purposes, shall be evaluated by the
Geotechnical Consultant during grading. Remedial removal depths shown on
geotechnical plans are estimates only. The actual extent of removal shall be determined
by the Geotechnical Consultant based on the field evaluation of exposed conditions
during grading. Where fill-over-cut slopes are to be graded, the cut portion of the slope
shall be made, evaluated, and accepted by the Geotechnical Consultant prior to placement
of materials for construction of the fill portion of the slope, unless otherwise
recommended by the Geotechnical Consultant.
7.0 Trench Backfills
7.1 Safety
The Contractor shall follow all OSHA and Cal/OSHA requirements for safety of
trench excavations.
LEIGHTON AND ASSOCIATES, INC.
General Earthwork and Grading Specifications
-7-
7.2 Bedding and Backfill
All bedding and backfill of utility trenches shall be performed in accordance with
the applicable provisions of Standard Specifications of Public Works
Construction. Bedding material shall have a Sand Equivalent greater than 30
(SE>30). The bedding shall be placed to 1 foot over the top of the conduit and
densified by jetting. Backfill shall be placed and densified to a minimum of
90 percent of relative compaction from 1 foot above the top of the conduit to the
surface.
The Geotechnical Consultant shall test the trench backfill for relative compaction.
At least one test should be made for every 300 feet of trench and 2 feet of fill.
7.3 Lift Thickness
Lift thickness of trench backfill shall not exceed those allowed in the Standard
Specifications of Public Works Construction unless the Contractor can
demonstrate to the Geotechnical Consultant that the fill lift can be compacted to
the minimum relative compaction by his alternative equipment and method.
7.4 Observation and Testing
The jetting of the bedding around the conduits shall be observed by the
Geotechnical Consultant.
FILL SLOPE
PROJECTED PLANE 1: 1
(HORIZONTAL: VERTICAL)
MAXIMUM FROM TOE
OF SLOPE TO
APPROVED GROUND
EXISTING
GROUND SURFACE
FILL-OVER-CUT SLOPE
-
CUT-OVER-ALL SLOPE
PROJECTED PLANE
1 TO 1 MAXIMUM
FROM TOE OF SLOPE
TO APPROVED GROUND
KEYING AND BENCHING
REMOVE
UNSUITABLE MATERIAL
REMOVE
UNSUITABLE MATERIAL
UT FACE SHALL BE
CONSTRUCTED PRIOR
TO FILL PLACEMENT
REMOVE
UNSUITABLE
MATERIAL
BENCHING SHALL BE DONE WHEN SLOPE'S
ANGLE IS EQUAL TO OR GREATER THAN 5: 1.
MINIMUM BENCH HEIGHT SHALL BE 4 FEET
AND MINIMUM FILL WIDTH SHALL BE 9 FEET.
GENERAL EARTHWORK AND GRADING
SPECIFICATIONS
STANDARD DETAILS A �Leighton
FINISH GRADE
_ - - - - - -·10•- - - -COMPACTEDFILL:._-_-_-_-_-_-_: MIN. -- - - - - - - - - - - - - ---------�---------------_-_-_-_-_-_ � -�----_-_-_-_-_-_-_-_-_ - -------7--------------� -------v------o.-------o---------------� -------_-_ -_-_-__ /--_-_-_-_-_-_-_-_-_-_ -_-_-_-_-_-_-_-_-_-_----- ·7-----------------------------7--------v-----u------------ ---------- ------_-_-_-_-,e_-_-_ o-_-_-_ -- ------------: er---_-- -10·- -. -7"'- - - -0 -I-a----------- -_-_-_-r:1J:N.:....
___ ...-:_- - -_-_-_-_-_-__ 4'MIN. _ -t� _ 15'MIN._-
_.-l---_---------p 7=�----n*-------�-��------- -- ----------------------------
- - - -,,,,�- - -_-..::_-_-_OVERSIZE --_-_-_-_-_-_-_ - ----
- - - - /"" - - - -_ _ _ _ WINDROW ___ _ �---7--------------
•Oversize rock is larger than 8 inches
in largest dimension.
•Backfill with approved soil jetted or
flooded in place to fill all the voids.
•Do not bury rock within 10 feet of
finish grade.
•Windrow of buried rock shall be
parallel to the finished slope face.
PROFILE ALONG WINDROW
SECTION A-A'
JETTED OR FLOODED
APPROVED SOIL
-_ ---------------- ----------------_ A' :-::::---::::-::::-::::-::::-::::-::::-::::-::::-::::-� --------_
JETTED OR FLOODED
APPROVED SOIL
� l .� �----------------------.---------------.----------,!
OVERSIZE ROCK DISPOSAL GENERAL EARTHWORK AND GRADING
SPECIFICATIONS
STANDARD DETAILS B
L_ ____________ _j_ ________ ____JL__ _____ ___J
�I
a. E � g
Cl a:
NATURALGROUND /
�----------::::-::::-::::-::::-::::-::::-::::-::::-::::-::::-::::-::::-::::-::::-::::-::::-::::-::::-::::-::::---�
"'�" ---��--------_:COMPACTED FILL:._-_-_---�------- -
TYPICAL BENCHING
-----------------�---.----..o..._-_-�_-_-_-_-_-_�---_-�----,,......... ----�----------::::-::::-::::-::::-::::-::::-::::-::::0
SUBDRAIN (See Alternates A and B)
FILTER MATERIAL SUBDRAIN ALTERNATE A PERFORATED PIPE SURROUNDED
WITH FILTER MATERIAL FILTER MATERIAL SHALL BE CLASS 2 PERMEABLE MATERIAL PER STATE OF
CALIFORNIA STANDARD SPECIFICATION, OR APPROVED ALTERNATE.
FILTER MATERIAL (9FT 3/FT) CLASS 2 GRADING AS FOLLOWS:
Sieve Size
1"
3/4"
3/8"
No.4
No.8
No. 30
No. 50
No.200
Percent Passing
100
90-100
40-100
25-40
18-33
5-15
0-7
0-3
SUBDRAIN ALTERNATE A-1 SUBDRAIN ALTERNATE A-2
ALTERNATE B-1
PERFORATED PIPE
6" 0 MIN.
SUBDRAIN ALTERNATE B
3/4" MAX. GRAVEL OR
APPROVED EQUIVALENT
(9FT 3 /FT)
ALTERNATE B-2
0 PERFORATED PIPE IS OPTIONAL PER
GOVERNING AGENCY'S REQUIREMENTS
DETAIL OF CANYON SUBDRAIN TERMINAL
DESIGN FINISHED GRADE
10' MIN. BACKFILL
r-15' MIN.---i---i--20' MIN. 5' MIN PERFORATED
6"0MIN.
· • 6"0 MIN.----i I NON-PERFORATED
FILTER FABRIC (MIRAFI 140N OR APPROVED EQUIVALENT)
� t :g ·e
1------------------,,------------------------,------------g
CANYON
SUBDRAIN
GENERAL EARTHWORK AND GRADING
SPECIFICATIONS a. E �gSTANDARD DETAILS C L...-----------------''------------------------1--------------' c.:
I .15' MIN� I �-��,,,..-����
OUTLET PIPES 4"1> NON-PERFORATED PIPE, 100' MAX. O.C. HORIZONTALLY 30' MAX. O.C. VERTICALLY
,,,/ / I / �,---------J
,,,,,, / I / ,..r ,,, ., I /·�/// /� ,,, , I �
/ --2% MIN. �� BACKCUT
/I
/ /
,,,
\ / I BENCHING // \ /i ,,,// \ /� 1'± / \ ,--_J J (! �/ _2% MIN.\ Jo1
. 2% MIN.---/ I SUBDRAIN ALTERNATE B
r•-----15' MIN.----·-1KEY DEPTH KEY WIDTH 2' MIN.
SUBDRAIN ALTERNATE A POSillVE SEAL SHOULD BE PROVIDED ----....
AT THE JOINT
CAL TRANS CLASS 2
,,o���, ;rr��:,��:
���""MIN
OUTLET PIPE (NON-PERFORATED)
3/4" ROCK (3FT.3/FT)-----
WRAPPED IN FILTER FABRIC
T-CONNECTION FROM
COLLECTION PIPE TO OUTLET PIPE
•SUBDRAIN INSTALLATION -Subdrain collector pipe shall be installed with perforations down or,unless otherwise designated by the geotechnical consultant. Outlet pipes shall be non-perforatedpipe. The subdrain pipe shall have at least 8 perforations uniformly spaced per foot. Perforation shall
•
•
be 1/4" to 1/2" if drilled holes are used. All subdrain pipes shall have a gradient at least 2% towards theoutlet.
SUBDRAIN PIPE -Subdrain pipe shall be ASTM D2751, ASTM D1527 (Schedule 40) or SDR 23.5 ABS pipeor ASTM D3034 (Schedule 40) or SDR 23.5 PVC pipe.
All outlet pipe shall be placed in a trench and, after fill is placed above it, rodded to verify integrity.
FILTER FABRIC (MIRAFI 140 OR APPROVED
EQUIVALENT)
� I
.ci ::, "'1
1-----------------""T"'"------------------.--------------tl
BUTTRESS OR
REPLACEMENT FILL
GENERAL EARTHWORK AND GRADING
SPECIFICATIONS
STANDARD DETAILS D SUBDRAINS � g
.__ _______________ _._ _______________ __._ _________ __,a:
OVERBURDEN OR UNSUITABLE
MATERIAL
CUT-FILL TRANSITION LOT OVEREXCAVATION
REMOVE
UNSUITABLE
\. GROUND \_..-----
SIDE HILL FILL FOR CUT PAD
OVEREXCAVATE
AND RECOMPACT
(REPLACEMENT FILL)
/
/
/
----
/ / /
/
4' MIN. <'\(/'
NATURAL
GROUND
�__-
__----
/ / / / /
FINISHED CUT PAD
L...=��.,......-.J.J--------SEE STANDARD DETAIL FOR SUBDRAINS
WHEN REQUIRED BY GEOTECHNICAL CONSUL TANT
KEY 2'MIN. �
DEPTH UNWEATHERED BEDROCK OR MATERIAL APPROVED
BY THE GEOTECHNICAL CONSULTANT
� t .!!!ii= 51
·� 1------------------------.---------------"T"""-------------1!!!
TRANSITION LOT FILLS AND SIDE HILL FILLS
GENERAL EARTHWORK AND GRADING
SPECIFICATIONS
STANDARD DETAILS E
a. E �gLeighton
.__ ___________________ __,_ ______________ _.__ _________ ____.a:
RETAINING WALL BACKFILL AND SUBDRAIN DETAIL
WITH PROPER
SURFACE DRAINAGE
SLOPE
OR LEVEL
CLASS 2 PERMEABLE
WEEP HOLE
WATERPROOFING
(SEE GENERAL NOTES)
LEVEL OR
SLOPE
12"
FILTER MATERIAL
NATIVE
¼ TO 1½ INCH SIZE GRAVEL
WRAPPED IN FILTER FABRIC
LEVEL OR
SLOPE
WEEP HOLE
SLOPE
OR LEVEL
12"
WITH PROPER
SURFACE DRAINAGE
4 INCH DIAMETER
PERFORATED PIPE
(SEE NOTE 3)
FILTER FABRIC
OPTION 1: PIPE SURROUNDED WITH
CLASS 2 PERMEABLE MATERIAL OPTION 2: GRAVEL WRAPPED
IN FILTER FABRIC
SUBDRAIN OPTIONS AND BACKFILL WHEN NATIVE MATERIAL HAS EXPANSION INDEX OF <50
Sieve Size
1"
3/4"
3/8"
No. 4
No. 8
No. 30
No. 50
No. 200
Percent Passing
100
90-100
40-100
25-40
18-33
5-15
0-7
0-3
Class 2 Filter Permeable Material Gradation
Per Caltrans Specifications
(SEE NOTE 5)
12" MINIMUM
(SEE GRADATION)
WATERPROOFING
(SEE GENERAL NOTES)(SEE NOTE 4)
12" MINIMUM
NATIVE
FOR WALLS 6 FEET OR LESS IN HEIGHT
(SEE NOTE 5)
WHEN NATIVE MATERIAL HAS EXPANSION INDEX OF <50
GENERAL NOTES:
* Waterproofing should be provided where moisture nuisance problem through the wall is undesirable.
* Water proofing of the walls is not under purview of the geotechnical engineer
* All drains should have a gradient of 1 percent minimum
*Outlet portion of the subdrain should have a 4-inch diameter solid pipe discharged into a suitable disposal area designed by the project
engineer. The subdrain pipe should be accessible for maintenance (rodding)
*Other subdrain backfill options are subject to the review by the geotechnical engineer and modification of design parameters.
Notes:
1) Sand should have a sand equivalent of 30 or greater and may be densified by water jetting.
2) 1 Cu. ft. per ft. of 1/4- to 1 1/2-inch size gravel wrapped in filter fabric
3) Pipe type should be ASTM D1527 Acrylonitrile Butadiene Styrene (ABS) SDR35 or ASTM D1785 Polyvinyl Chloride plastic (PVC), Schedule
40, Armco A2000 PVC, or approved equivalent. Pipe should be installed with perforations down. Perforations should be 3/8 inch in diameter
placed at the ends of a 120-degree arc in two rows at 3-inch on center (staggered)
4) Filter fabric should be Mirafi 140NC or approved equivalent.
5) Weephole should be 3-inch minimum diameter and provided at 10-foot maximum intervals. If exposure is permitted, weepholes should be
located 12 inches above finished grade. If exposure is not permitted such as for a wall adjacent to a sidewalk/curb, a pipe under the sidewalk
to be discharged through the curb face or equivalent should be provided. For a basement-type wall, a proper subdrain outlet system should be
provided.
6) Retaining wall plans should be reviewed and approved by the geotechnical engineer.
7) Walls over six feet in height are subject to a special review by the geotechnical engineer and modifications to the above requirements.
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APPENDIX D
GBA - IMPORTANT INFORMATION ABOUT THIS
GEOTECHNICAL ENGINEERING REPORT
Geotechnical-Engineering Report
Important Information about This
Subsurface problems are a principal cause of construction delays, cost overruns, claims, and disputes.
While you cannot eliminate all such risks, you can manage them. The following information is provided to help.
The Geoprofessional Business Association (GBA)
has prepared this advisory to help you – assumedly
a client representative – interpret and apply this
geotechnical-engineering report as effectively as
possible. In that way, you can benefit from a lowered
exposure to problems associated with subsurface
conditions at project sites and development of
them that, for decades, have been a principal cause
of construction delays, cost overruns, claims,
and disputes. If you have questions or want more
information about any of the issues discussed herein,
contact your GBA-member geotechnical engineer.
Active engagement in GBA exposes geotechnical
engineers to a wide array of risk-confrontation
techniques that can be of genuine benefit for
everyone involved with a construction project.
Understand the Geotechnical-Engineering Services
Provided for this Report
Geotechnical-engineering services typically include the planning,
collection, interpretation, and analysis of exploratory data from
widely spaced borings and/or test pits. Field data are combined
with results from laboratory tests of soil and rock samples obtained
from field exploration (if applicable), observations made during site
reconnaissance, and historical information to form one or more models
of the expected subsurface conditions beneath the site. Local geology
and alterations of the site surface and subsurface by previous and
proposed construction are also important considerations. Geotechnical
engineers apply their engineering training, experience, and judgment
to adapt the requirements of the prospective project to the subsurface
model(s). Estimates are made of the subsurface conditions that
will likely be exposed during construction as well as the expected
performance of foundations and other structures being planned and/or
affected by construction activities.
The culmination of these geotechnical-engineering services is typically a
geotechnical-engineering report providing the data obtained, a discussion
of the subsurface model(s), the engineering and geologic engineering
assessments and analyses made, and the recommendations developed
to satisfy the given requirements of the project. These reports may be
titled investigations, explorations, studies, assessments, or evaluations.
Regardless of the title used, the geotechnical-engineering report is an
engineering interpretation of the subsurface conditions within the context
of the project and does not represent a close examination, systematic
inquiry, or thorough investigation of all site and subsurface conditions.
Geotechnical-Engineering Services are Performed
for Specific Purposes, Persons, and Projects,
and At Specific Times
Geotechnical engineers structure their services to meet the specific
needs, goals, and risk management preferences of their clients. A
geotechnical-engineering study conducted for a given civil engineer
will not likely meet the needs of a civil-works constructor or even a
different civil engineer. Because each geotechnical-engineering study
is unique, each geotechnical-engineering report is unique, prepared
solely for the client.
Likewise, geotechnical-engineering services are performed for a specific
project and purpose. For example, it is unlikely that a geotechnical-
engineering study for a refrigerated warehouse will be the same as
one prepared for a parking garage; and a few borings drilled during
a preliminary study to evaluate site feasibility will not be adequate to
develop geotechnical design recommendations for the project.
Do not rely on this report if your geotechnical engineer prepared it:
• for a different client;
• for a different project or purpose;
• for a different site (that may or may not include all or a portion of
the original site); or
• before important events occurred at the site or adjacent to it;
e.g., man-made events like construction or environmental
remediation, or natural events like floods, droughts, earthquakes,
or groundwater fluctuations.
Note, too, the reliability of a geotechnical-engineering report can
be affected by the passage of time, because of factors like changed
subsurface conditions; new or modified codes, standards, or
regulations; or new techniques or tools. If you are the least bit uncertain
about the continued reliability of this report, contact your geotechnical
engineer before applying the recommendations in it. A minor amount
of additional testing or analysis after the passage of time – if any is
required at all – could prevent major problems.
Read this Report in Full
Costly problems have occurred because those relying on a geotechnical-
engineering report did not read the report in its entirety. Do not rely on
an executive summary. Do not read selective elements only. Read and
refer to the report in full.
You Need to Inform Your Geotechnical Engineer
About Change
Your geotechnical engineer considered unique, project-specific factors
when developing the scope of study behind this report and developing
the confirmation-dependent recommendations the report conveys.
Typical changes that could erode the reliability of this report include
those that affect:
• the site’s size or shape;
• the elevation, configuration, location, orientation,
function or weight of the proposed structure and
the desired performance criteria;
• the composition of the design team; or
• project ownership.
As a general rule, always inform your geotechnical engineer of project
or site changes – even minor ones – and request an assessment of their
impact. The geotechnical engineer who prepared this report cannot accept
responsibility or liability for problems that arise because the geotechnical
engineer was not informed about developments the engineer otherwise
would have considered.
Most of the “Findings” Related in This Report
Are Professional Opinions
Before construction begins, geotechnical engineers explore a site’s
subsurface using various sampling and testing procedures. Geotechnical
engineers can observe actual subsurface conditions only at those specific
locations where sampling and testing is performed. The data derived from
that sampling and testing were reviewed by your geotechnical engineer,
who then applied professional judgement to form opinions about
subsurface conditions throughout the site. Actual sitewide-subsurface
conditions may differ – maybe significantly – from those indicated in
this report. Confront that risk by retaining your geotechnical engineer
to serve on the design team through project completion to obtain
informed guidance quickly, whenever needed.
This Report’s Recommendations Are
Confirmation-Dependent
The recommendations included in this report – including any options or
alternatives – are confirmation-dependent. In other words, they are not
final, because the geotechnical engineer who developed them relied heavily
on judgement and opinion to do so. Your geotechnical engineer can finalize
the recommendations only after observing actual subsurface conditions
exposed during construction. If through observation your geotechnical
engineer confirms that the conditions assumed to exist actually do exist,
the recommendations can be relied upon, assuming no other changes have
occurred. The geotechnical engineer who prepared this report cannot assume
responsibility or liability for confirmation-dependent recommendations if you
fail to retain that engineer to perform construction observation.
This Report Could Be Misinterpreted
Other design professionals’ misinterpretation of geotechnical-
engineering reports has resulted in costly problems. Confront that risk
by having your geotechnical engineer serve as a continuing member of
the design team, to:
• confer with other design-team members;
• help develop specifications;
• review pertinent elements of other design professionals’ plans and
specifications; and
• be available whenever geotechnical-engineering guidance is needed.
You should also confront the risk of constructors misinterpreting this
report. Do so by retaining your geotechnical engineer to participate in
prebid and preconstruction conferences and to perform construction-
phase observations.
Give Constructors a Complete Report and Guidance
Some owners and design professionals mistakenly believe they can shift
unanticipated-subsurface-conditions liability to constructors by limiting
the information they provide for bid preparation. To help prevent
the costly, contentious problems this practice has caused, include the
complete geotechnical-engineering report, along with any attachments
or appendices, with your contract documents, but be certain to note
conspicuously that you’ve included the material for information purposes
only. To avoid misunderstanding, you may also want to note that
“informational purposes” means constructors have no right to rely on
the interpretations, opinions, conclusions, or recommendations in the
report. Be certain that constructors know they may learn about specific
project requirements, including options selected from the report, only
from the design drawings and specifications. Remind constructors
that they may perform their own studies if they want to, and be sure to
allow enough time to permit them to do so. Only then might you be in
a position to give constructors the information available to you, while
requiring them to at least share some of the financial responsibilities
stemming from unanticipated conditions. Conducting prebid and
preconstruction conferences can also be valuable in this respect.
Read Responsibility Provisions Closely
Some client representatives, design professionals, and constructors do
not realize that geotechnical engineering is far less exact than other
engineering disciplines. This happens in part because soil and rock on
project sites are typically heterogeneous and not manufactured materials
with well-defined engineering properties like steel and concrete. That
lack of understanding has nurtured unrealistic expectations that have
resulted in disappointments, delays, cost overruns, claims, and disputes.
To confront that risk, geotechnical engineers commonly include
explanatory provisions in their reports. Sometimes labeled “limitations,”
many of these provisions indicate where geotechnical engineers’
responsibilities begin and end, to help others recognize their own
responsibilities and risks. Read these provisions closely. Ask questions.
Your geotechnical engineer should respond fully and frankly.
Geoenvironmental Concerns Are Not Covered
The personnel, equipment, and techniques used to perform an
environmental study – e.g., a “phase-one” or “phase-two” environmental
site assessment – differ significantly from those used to perform a
geotechnical-engineering study. For that reason, a geotechnical-engineering
report does not usually provide environmental findings, conclusions, or
recommendations; e.g., about the likelihood of encountering underground
storage tanks or regulated contaminants. Unanticipated subsurface
environmental problems have led to project failures. If you have not
obtained your own environmental information about the project site,
ask your geotechnical consultant for a recommendation on how to find
environmental risk-management guidance.
Obtain Professional Assistance to Deal with
Moisture Infiltration and Mold
While your geotechnical engineer may have addressed groundwater,
water infiltration, or similar issues in this report, the engineer’s
services were not designed, conducted, or intended to prevent
migration of moisture – including water vapor – from the soil
through building slabs and walls and into the building interior, where
it can cause mold growth and material-performance deficiencies.
Accordingly, proper implementation of the geotechnical engineer’s
recommendations will not of itself be sufficient to prevent
moisture infiltration. Confront the risk of moisture infiltration by
including building-envelope or mold specialists on the design team.
Geotechnical engineers are not building-envelope or mold specialists.
Copyright 2019 by Geoprofessional Business Association (GBA). Duplication, reproduction, or copying of this document, in whole or in part, by any means whatsoever, is strictly
prohibited, except with GBA’s specific written permission. Excerpting, quoting, or otherwise extracting wording from this document is permitted only with the express written permission of
GBA, and only for purposes of scholarly research or book review. Only members of GBA may use this document or its wording as a complement to or as an element of a report of any kind.
Any other firm, individual, or other entity that so uses this document without being a GBA member could be committing negligent or intentional (fraudulent) misrepresentation.
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