Polo Villas TR 33085 BCPR2023-0002 - Geotechnical ReportLANDMARK
a MBE Company
August 26, 2022
Mr. Jeff Nielsen
Build To Stay, LLC
2425 S. Stearman Drive, Suite 220
Chandler, AZ 85386
Subject: Geotechnical Report Update
Tract No. 33085
La Quinta, California
LCI Report No.: LP22251
780 N. 4th Street
El Centro, CA 92243
(760) 370-3000
landmark@landmark-ca.com
77-948 Wildcat Drive
Palm Desert, CA 92211
(760) 360-0665
gchandra@landmark-ca.com
Reference: Geotechnical Investigation Report for the subject project prepared by
LandMark Consultants, Inc., Revised Dated May 23, 2005.
Dear Mr. Nielsen:
As requested, LandMark Consultants, Inc., is providing an update report to the referenced
geotechnical investigation report for the proposed single-family residences on south-west corner of
Madison Street and Beth Circle in the city of La Quinta, California. The initial field investigation
was conducted in April 2005, and the report was issued by our office dated May 23, 2005, and
update reports dated July 5, 2006, and May 15, 2017.
Our site visit on August 22, 2022, found that the site conditions were similar as those reported in the
referenced report during the initial site investigation conducted in 2005, update report in 2006 and
2017.
Based on our present field observations and the clients similar project intentions for new commercial
buildings, it is our opinion that the findings, recommendations, and conclusions in the referenced
geotechnical investigation and update reports are still applicable, except for the seismic design
parameters, which have been updated in the current California Building Code.
Tract No. 33085
LCI Report No.: LP22251
General Ground Motion Analysis
The project site is considered likely to be subjected to moderate to strong ground motion from
earthquakes in the region. Ground motions are dependent primarily on the earthquake magnitude
and distance to the seismogenic (rupture) zone. Acceleration magnitudes also are dependent upon
attenuation by rock and soil deposits, direction of rupture and type of fault; therefore, ground
motions may vary considerably in the same general area.
2019 CBC General Ground Motion Parameters: The California Building Code (CBC) requires that a
site -specific ground motion hazard analysis be performed in accordance with ASCE 7-16 Section
11.4.8 for structures on Site Class D and E sites with Si greater than or equal to 0.2 and Site Class E
sites with S, greater than or equal to 1.0. This project site has been classified as Site Class D and
has a S1 value of 0.64, which would require a site -specific ground motion hazard analysis.
However, ASCE 7-16 Section 11.4.8 provides three exceptions which permit the use of conservative
values of design parameters for certain conditions for Site Class D and E sites in lieu of a site -
specific hazard analysis. The exceptions are:
• Exception 1: Structures on Site Class E sites with S, greater than or equal to 1.0, provided
the site coefficient Fa is taken as equal to that of Site Class C.
• Exception 2: Structures on Site Class D sites with Si greater than or equal to 0.2, provided
the value of the seismic response coefficient C, is determined by Equations
12.8-2 for values of T < 1.5Ts and taken as equal to 1.5 times the value
computed in accordance with either Equation 12.8-3 for TL > T >1.5Ts or
Equation 12.8-4 for T> TL.
• Exception 3: Structures on Site Class E sites with Si greater than or equal to 0.2, provided
that T is less than or equal to Ts and the equivalent static force procedure is
used for design.
Based on our understanding of the proposed development, the seismic design parameters presented
in Table 2 were calculated assuming that one of the exceptions listed above applies to the proposed
structures at this site. However, the structural engineer should verify that one of the exceptions
is applicable to the proposed structures. If none of the exceptions apply, our office should be
consulted to perform a site -specific ground motion hazard analysis.
The 2019 CBC general ground motion parameters are based on the Risk -Targeted Maximum
Considered Earthquake (MCER). The Structural Engineers Association of California (SEAOC)
and Office of Statewide Health Planning and Development (OSHPD) Seismic Design Maps Web
LandMark Consultants, Inc. Page 2
Tract No. 33085 LCI Report No.: LP22251
Application (SEAOC, 2020) was used to obtain the site coefficients and adjusted maximum
considered earthquake spectral response acceleration parameters. Design spectral response
acceleration parameters are defined as the earthquake ground motions that are two-thirds (2/3) of
the corresponding MCER ground motions. The Maximum Considered Earthquake Geometric
Mean (MCEG) peak ground acceleration adjusted for soil site class effects (PGAM) value to be
used for liquefaction and seismic settlement analysis in accordance with 2019 CBC Section
1803A.5.12 (PGAM = FPGA*PGA) is estimated at 0.75g for the project site. Design earthquake
ground motion parameters are provided in Table 2.
Closure
We have prepared this report for your exclusive use in accordance with the generally accepted
geotechnical engineering practice as it existed within the site area at the time of our study. No
warranty is expressed or implied. It should be noted that the submitted plans were not reviewed for
conformance with other clients, governmental or consultant requirements.
We recommend that Landmark Consultants, Inc. be retained to provide the tests and observations
services during construction. The geotechnical engineering firm providing such tests and
observations shall become the geotechnical engineer of record and assume responsibility for the
project.
Landmark Consultants, Inc. recommendations for this site are, to a high degree, dependent upon
appropriate quality control of subgrade preparation, fill placement, and foundation construction.
Accordingly, the findings and professional opinions in this report are made contingent upon the
opportunity for Landmark Consultants, Inc. to observe grading operations and foundation
excavations for the proposed construction.
Ifparties other than Landmark Consultants, Inc. are engaged to provide observation and testing
services during construction, such parties must be notified that they will be required to assume
complete responsibility as the geotechnical engineer of record for the geotechnical phase of the
project by concurring with the recommendations in this report and/or by providing alternative
recommendations.
LandMark Consultants, Inc. Page 3
Tract No. 33085
LCI Report No.: LP22251
Additional information concerning the scope and cost of these services can be obtained from our
office.
We appreciate the opportunity to be of service. Should you have any questions, please call our
office at (760)360-0665.
Sincerely Yours,
LandMark Consultants, Inc.
ALT
Greg M. Chandra, P.E., M.ASCE
Principal Engineer
Attachments:
Quo F ESSlG,/�
v Z
c NO, C 34432 rr
T, CIVIL
�CFCA1.
Appendix A: Referenced Geotechnical Reports prepared by LandMark Consultants, Inc.,
Revised dated May 23, 2005.
LandMark Consultants, Inc. Page 3
Tract No.: 33065
LCI Project No. LP22251
Table 2
2019 California Building Code (CBC) and ASCE 7-16 Seismic Parameters
ASCE 7-16 Reference
Soil Site Class:
D
Table 20.3-1
Latitude:
33.6758
N
Longitude:-116.2525
W
Risk Category:
II
Seismic Design Category:
D
Maximum Considered Earthquake (MCE)
Ground Motion
Mapped MCEo Short Period Spectral Response
SS
1.560 g
ASCE Figure 22-1
Mapped NICER 1 second Spectral Response
S,
0.640 g
ASCE Figure 22-2
Short Period (0.2 s) Site Coefficient
Fe
1.00
ASCE Table 11.4-1
Long Period (1.0 s) Site Coefficient
F,
1.70
ASCE Table 11.4-2
MCEo Spectral Response Acceleration Parameter (0.2 s)
SMs
1.560 g
= Fa * SS ASCE Equation 11.4-1
MCEo Spectral Response Acceleration Parameter (1.0 s)
Sm,
1.088 g
= Fv * Si ASCE Equation 11.4-2
Design Earthquake Ground Motion
Design Spectral Response Acceleration Parameter (0.2 s)
SDS
1.040 g
= 2/3*SMs ASCE Equation 11.4-3
Design Spectral Response Acceleration Parameter (1.0 s)
SDI
0.725 g
= 2/3*SM, ASCE Equation 11.4-4
Risk Coefficient at Short Periods (less than 0.2 s)
CRs
0.901
ASCE Figure 22-17
Risk Coefficient at Long Periods (greater than 1.0 s)
CRI
0.886
ASCE Figure 22-18
TL
8.00 sec
ASCE Figure 22-12
To
0.14 sec
=0.2*SDI/SDS
Ts
0.70 sec
=SDI/SDS
Peak Ground Acceleration
PGAm
0.75 g
ASCE Equation 11.8-1
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11
LANflMARK
a DBE/MBE/SBE Company
780 N 4th Street
May 23, 2005
El Centro, CA 92243
(7601 370.3000
t760t 337-E900 fax
Mr. David Neale
77-946 Wild= Drive
Palm Desert. CA 92211
Core Homes, LLC
;7601360-0665
�76C' 360-0621 ax
470 S. Market Street
San Jose, CA 95113
Geotechnical Investigation
Tentative Tract No: 33085
4.4-acre Property
La Quinta, California
LCI Report No. LP05057
Dear Mr. Neale:
This geotecluiical report is provided for design and construction of the proposed single family
residential development located on the southwest corner of Beth Circle and Madison Street, between
Avenue 51 and Avenue 52 in La Quinta, California. Our geotechnical investigation was conducted
in response to your request for our services. The enclosed report describes our soil engineering
investigation and presents our professional opinions regarding geotechnical conditions at the site to
be considered in the design and construction of the project.
The findings of this study indicate the site is underlain by interbedded silty sands, sandy silts, and
clayey sandy silts with near surface silty sands. The subsurface soils are very loose to medium dense
in nature. Groundwater was not encountered in the borings during the time of field exploration.
Elevated sulfate and chloride levels were not encountered in the soil samples tested for this study.
However, the soil is moderately corrosive to metal. We recommend a minimum of 2,500 psi
concrete Type II Portland Cement with a maximum water/cement ratio of0.60 (by weight) should be
used for concrete placed in contact with native soils of this project.
We did not encounter soil conditions that would preclude implementation of the proposed project
provided the recommendations contained in this report are implemented in the design and
construction of this project. Our findings, recommendations, and application options are related ottlp
throngh reading thefull report, and are best evaluated with the active participation of the engineer
of record who developed them.
Tentative Tract No. 33035 — La Quinta, CA LCI Report No. 1.1105057
We appreciate the opportunity to provide our findings and professional opinions regarding
geotecfmical conditions at the site. If you have any questions or comments regarding our findings,
please call our office at (760) 360-0665.
Respectfully Submitted,
Landmark Consultants, Inc.
P41-lKlyY1 No dmeyerStaeologist o�oF
Nc. C 34a 32
EORES 09-30-05
GregV.\ChanAja, PE
Principa Engi I
r
Distribution:
Client (4)
a
atiqul Alam
Staff Engineer
Tentative Tract No. 33085 — La Quinta, CA LCI Report No. LP05057
TABLE OF CONTENTS
Pauc
Sectionl..........................................................................................................................................
I
INTRODUCTION.......................................................................................................................
I
1.1 Project Description...........................................................................................................1
1.2 Purpose and Scope of Work.............................................................................................1
1.3 Authorization....................................................................................................................2
Section2.............. ............................................................................................................................3
METHODS OF INVESTIGATION............................................................................................3
2.1 Field Exploration..............................................................................................................3
2.2 Laboratory Testing...........................................................................................................4
Section3..........................................................................................................................................
5
DISCUSSION..............................................................................................................................
5
3.1 Site Conditions.................................................................................................................
5
3.2 Geologic Setting...............................................................................................................5
3.3 Seismicity and Faulting...................................................................................................6
3.4 Site Acceleration and CBC Seismic Coefficients.............................................................7
3.5 Subsurface Soil.................................................................................................................8
3.6 Groundwater ................... ..................................................................................................8
3.7 Hydroconsolidation...........................................................
3.8 Soil Infiltration Rate.........................................................................................................9
Section4...............................................................................................................
RECOMMENDATIONS...........................................................................................................10
4.1 Site Preparation...............................................................................................................10
4.2 Foundations and Settlements..........................................................................................12
4.3 Slabs-On-Grade..............................................................................................................13
4.4 Concrete Mixes and Corrosivity .....................................................................................14
4.5 Excavations.....................................................................................................................15
4.6 Lateral Earth Pressures...................................................................................................15
4.7 Seismic Design...............................................................................................................16
4.8 Pavements.......................................................................................................................16
Section5........................................................................................................................................18
LIMITATIONS AND ADDITIONAL SERVICES...................................................................18
5.1 Limitations......................................................................................................................18
5.2 Additional Services.........................................................................................................19
APPENDIX A: Vicinity and Site Maps
APPENDIX B: Subsurface Soil Logs and Soil Key
APPENDIX C: Laboratory Test Results
APPENDIX D: Summary of Infiltration Testing
APPENDIX E: References
Tentative "tract No. 33085 — La Quinta. CA LCI Report No. LP05057
Section
INTRODUCTION
1.1 Project Description
This report presents the findings of our geotechnical investigation for the proposed single family
residential development located on the southwest corner of Beth Circle and Madison Street, between
Avenue 51 and Avenue 52 in La Quinta, California (See Vicinity Map, Plate A-1). The proposed
development will consist of seven one to two story, single family residential homes on approximately
4.4-acres. A site plan for the proposed development was provided by Coachella Valley Engineers,
[tic. of Palm Desert, California.
The structures are planned to consist of continuous footing with slabs -on -grade and wood -frame
construction. Footing loads at exterior bearing walls are estimated at 1 to 3 kips per lineal foot.
Column loads are estimated to range from 5 to 15 kips. If structural loads exceed those stated above,
we should be notified so we may evaluate their impact on foundation settlement and bearing
capacity. Site development will include building pad preparation, underground utility installation,
street construction and concrete driveway and sidewalk placement.
1.2 Purpose and Scope of Work
The purpose of this geotechnical study was to investigate the upper 51.5 feet of subsurface soil at
selected locations within the site for evaluation of physical/engineering properties. From the
subsequent field and laboratory data, professional opinions were developed and are provided in this
report regarding geotechnical conditions at this site and the effect on design and construction. The
scope of our services consisted of the following:
► Field exploration and in -situ testing of the site soils at selected locations and depths.
► Laboratory testing for physical and/or chemical properties of selected samples.
► Review of the available literature and publications pertaining to local geology,
faulting, and seismicity.
► Engineering analysis and evaluation of the data collected.
► Preparation of this report presenting our findings, professional opinions, and
recommendations for the geotechnical aspects of project design and construction.
Landmark Consultants. Inc. Page 1
Tentative 'tract No. 33085 — La Quinta. CA LCI Report No. LP05057
► In -situ testing of soil infiltration for stormwater retention basin.
This report addresses the following geotechnical issues:
► Subsurface soil and groundwater conditions
► Site geology, regional faulting and seismicity, near source factors, and site seismic
accelerations
► Aggressive soil conditions to metals and concrete
► Soil infiltration rates of the native soil for a stormwater retention basin
Professional opinions with regard to the above issues are presented for the following:
► Site grading and earthwork
► Building pad and foundation subgrade preparation
► Allowable soil bearing pressures and expected settlements
► Concrete slabs -on -grade
► Lateral earth pressures
► Excavation conditions and buried utility installations
► Mitigation of the potential effects of salt concentrations in native soil to concrete
mixes and steel reinforcement
► Seismic design parameters
► Preliminary pavement structural sections
Our scope of work for this report did not include an evaluation of the site for the presence of
environmentally hazardous materials or conditions.
1.3 Authorization
Mr. Anthony Ramirez of Coachella Valley Engineers, Inc. provided authorization by verbal
agreement to proceed with our work on March 7, 2005. We conducted our work according to our
written proposal dated March 3, 2005.
Landmark Consultants. Inc. Page
Tentative Tract No.3308_5 — La Quinta. CA LCI Report No. LP05057
Section 2
METHODS OF INVESTIGATION
2.1 Field Exploration
Subsurface exploration was performed on April 18, 2005 using Williams Drilling of Indio, California
to advance three (3) borings to depths of 13.5 to 51.5 feet below existing ground surface. The
borings were advanced with a truck -mounted, CME 55 drill rig using 8-inch diameter, hollow -stem,
continuous -Flight augers. The approximate boring locations were established in the field and plotted
on the site map by sighting to discernable site features. The boring locations are shown on the Site
and Exploration Plan (Plate A-2).
A staff geologist observed the drilling operations and maintained a log of the soil encountered and
sampling depths, visually classified the soil encountered during drilling in accordance with the
Unified Soil Classification System, and obtained drive tube and bulk samples of the subsurface
materials at selected intervals. Relatively undisturbed soil samples were retrieved using a 2-inch
outside diameter (OD) split -spoon sampler or a 3-inch OD Modified California Split -Barrel (ring)
sampler. The samples were obtained by driving the sampler ahead of the auger tip at selected depths.
The drill rig was equipped with a 140-pound CME automatic hammer for conducting Standard
Penetration Tests (SPT). The number of blows required to drive the samplers the last 12 inches of an
18 inch drive length into the soil is recorded on the boring logs as "blows per foot". Blow counts (N
values) reported on the boring logs represent the field blow counts. No corrections have been
applied for effects of overburden pressure, automatic hammer drive energy, drill rod lengths, liners,
and sampler diameter.
After logging and sampling the soil, the exploratory borings were backfilled with the excavated
material. The backfill was loosely placed and was not compacted to the requirements specified for
engineered fill.
The subsurface logs are presented on Plates B-1 through B-3 in Appendix B. A key to the log
symbols is presented on Plate B-4. The stratification lines shown on the subsurface logs represent
the approximate boundaries between the various strata. However, the transition from one stratum to
another may be gradual over some range of depth.
Landmark Consultants, Inc. Page 3
Tentative Tract No.33085 — La Quinta. CA LCI Report No. LP05057
2.2 Laboratory, Testing
Laboratory tests were conducted on selected bulk and relatively undisturbed soil samples to aid in
classification and evaluation of selected engineering properties of the site soils. The tests were
conducted in general conformance to the procedures of the American Society for Testing and
Materials (ASTM) or other standardized methods as referenced below. The laboratory testing
program consisted of the following tests:
► Particle Size Analyses (ASTM D422) — used for soil classification.
► Unit Dry Densities (ASTM D2937) and Moisture Contents (ASTM D2216) — used for
insitu soil parameters.
► Collapse Potential (ASTM D5333) — used for hydroconsolidation potential evaluation.
► Moisture -Density Relationship (ASTM D 1557) — used for soil compaction determinations.
P. Direct Shear (ASTM D3080) — used for soil strength determination.
► Chemical Analyses (soluble sulfates & chlorides, pH, and resistivity) (Caltrans Methods) —
used for concrete mix evaluations and corrosion protection requirements.
The laboratory test results are presented on the subsurface logs and on Plates C-I through C-4 in
Appendix C.
Landmark Consultants. Inc. Page 4
Tentative Tract No.33085 — La Quinta, CA LCI Report No. LP05057
Section 3
DISCUSSION
3.1 Site Conditions
The project site is relatively rectangular in shape, elongated in the east -west direction, is flat -lying
and consists of approximately 4.4-acres. The site is currently occupied by a citrus grove, with rows
orientated in an east -west direction. A concrete block wall separates the site from the adjacent
properties to the northwest, west and south. Madison Street. a rural two-lane roadway, is located to
the east and Beth Circle is to the northeast of the site.
Adjacent properties are flat -lying and are approximately at the same elevation with this site. A date
palm grove is located to the south and a single family residential development is located to the west
and across Beth Circle to the north. The Empire Polo Club is located across Madison Street to the
east. The All American Canal is located further to the west.
The project site lies at an elevation of approximately 10 feet below mean sea level in the Coachella
Valley region of the California low desert. Annual rainfall in this and region is less than 4 inches per
year with four months of average summertime temperatures above 100°F. Winter temperatures are
mild, seldom reaching freezing.
3.2 Geologic Setting
The project site is located in the Coachella Valley portion of the Salton Trough physiographic
province. The Salton Trough is a geologic structural depression resulting from large scale regional
faulting. The trough is bounded on the northeast by the San Andreas Fault and Chocolate Mountains
and the southwest by the Peninsular Range and faults of the San Jacinto Fault Zone. The Salton
Trough represents the northward extension of the Gulf of California, containing both marine and
non -marine sediments since the Miocene Epoch. Tectonic activity that formed the trough continues
at a high rate as evidenced by deformed young sedimentary deposits and high levels of seismicity.
Figure I shows the location of the site in relation to regional faults and physiographic features.
The surrounding regional geology includes the Peninsular Ranges (Santa Rosa and San Jacinto
Mountains) to the south and west, the Salton Basin to the southeast, and the Transverse Ranges
Landmark Consultants. Inc. Page 5
Centative Tract No.33085 — La Quinta. CA LCI Report No. LP050_57
(Little San Bernardino and Orocopia Mountains) to the north and east. Hundreds of feet to several
thousand feet of Quaternary fluvial, lacustrine, and aeolian soil deposits underlay the Coachella
Valley.
The southeastern part of the Coachella Valley lies below sea level. In the geologic past, the ancient
Lake Cahuilla submerged the area. Calcareous tufa deposits may be observed along the ancient
shoreline as high as elevation 45 to 50 feet MSL along the Santa Rosa Mountains from La Quinta
southward. Lacustrine (lake bed) deposits comprise the subsurface soils over much of the eastern
Coachella Valley with alluvial outwash along the flanks of the valley.
3.3 Seismicity and Faulting
Faulting and Seismic Sources: We have performed a computer -aided search of known faults or
seismic zones that lie within a 62 mile (100 kilometers) radius of the project site as shown on Figure
1 and Table 1. The search identifies known faults within this distance and computes deterministic
ground accelerations at the site based on the maximum credible earthquake expected on each of the
faults and the distance from the fault to the site. The Maximum Magnitude Earthquake (Mmax)
listed was taken from published geologic information available for each fault (CDMG OFR 96-08
and Jennings. 1994).
Seismic Risk: The project site is located in the seismically active Coachella Valley of southern
California and is considered likely to be subjected to moderate to strong ground motion from
earthquakes in the region. The proposed site structures should be designed in accordance with the
California Building Code for near source factors derived from a "Design Basis Earthquake" (DBE).
The DBE is defined as the motion having a 10 percent probability of being exceeded in 50 years.
Seismic Hazards.
► Groundshaking. The primary seismic hazard at the project site is the potential for strong
groundshaking during earthquakes along the San Andreas Fault. A further discussion of
groundshaking follows in Section 3.4.
► Surface Rupture. The project site does not lie within a State of California, Alquist-Priolo
Earthquake Fault Zone. Surface fault rupture is considered to be unlikely at the project site because
of the well -delineated fault lines through the Coachella Valleyas shown on USGS and CDMG maps.
Landmark Consultants. Inr. Page 6
"I entailve Tract No. 33085 - La Quinta, CA
L C'I Report No. LP05057
Table 1
FAULT PARAMETERS & DETERMINISTIC
ESTIMATES OF PEAK GROUND ACCELERATION (PGA)
Distance
Maximum
Avg
Avg
Date of
Largest
Est.
Fault Name or
(mi) &
Fault
Fault
Magnitude
Slip
Return
Last
Historic
Site
Seismic Zone
Direction
Type
Length
Mmax
Rate
Period
Rupture
Event
PGA
_
from Site
(km)
(Mw)
(mm/yr)
(yrs)
(year)
>5.5M (year)
(g)
Reference Notes: (1)
(2) (3)
(2)
(4)
(3)
(3)
(3)
(5)
(6)
San Andreas Fault System
Coachella Valley
6.0
NE
A
A
95
7.4
25
220
1690+/-
6.5
1948
0.41
- San Gorgonio -Banning
7.6
N
A
A
98
7.4
10
---
1690+/-
6.2
1986
0.35
- San Bernardino Mtn
27
NW
A
A
107
7.3
24
433
1812
6.5
1812
0.13
- Whole S. Calif. Zone
6.0
NE
A
A
345
7.9
---
---
1857
78
1857
0.53
San Jacinto Fault System
Hot Spgs-Buck Ridge
16
SW
B
A
70
6.5
2
354
6.3
1937 1
0.13
- Anza Segment
19
SSW
A
A
90
7.2
12
250
1918
6.8
1918
0.17
Coyote Creek
22
SW
B
A
40
6.8
4
175
1968
6.5
1968
0.12
- Borrego Mtn
33
S
B
A
29
6.6
4
175
6.5
1942
0.08
- San Jacinto Valley
39
W
B
A
42
6.9
12
83
6.8
1899
0.08
- Elmore Ranch
46
SE
B
A
29
6.6
1
225
1987
5.9
1987
0.06
- Superstition Mtn.
50
SSE
B
A
23
6.6
5
500
1440 +/-
0.06
- Superstition Hills
51
SSE
B
A
22
6.6
4
250
1987
6.5
1987
0.06
- San Bernardino Seg.
61
WNW
B
A
35
6.7
12
100
6.0
1923
0.05
- Whole Zone
20
WSW
A
A
245
7.5
---
---
0.18
Mojave Faults
Blue Cut
16
N
B
C
30
6.8
1
762
0.15
Eureka Peak
20
NNW
C
C
19
6.4
0.6
5.000
1992
6.1
1992
0.10
Burnt Mtn
20
NNW
B
C
20
6.4
0.6
5,000
1992
7.3
1992
0.10
Morongo
31
NW
C
C
23
6.5
0.6
1.172
5.5
1947
0.08
Pinto Mountain
32
N
B
B
73
7.0
2.5
499
0.10
Bullion Mtn -Mesquite Lk
34
NNE
B
C
88
7.0
0.6
5.000
0.10
S. Emerson -Copper Mtn.
34
N
B
C
54
6.9
0.6
5,000
0.09
Landers
35
NNW
B
C
83
7.3
0.6
5,000
1992
7.3
1992
0.11
N. Johnson Valley
44
NNW
B
C
36
6.7
0.6
5.000
0.07
Notes: -
1. Jennings (1994) and CDMG (1996)
2 CDMG (1996), where Type A faults -- slip rate >5 mm/yr and well constrained paleoseismic data
Type B faults -- all other faults-
3 WGCEP (1995)
4. CDMG (1996) based on Wells & Coppersmith (1994)
5. Ellsworth Catalog in USGS PP 1515 (1990) and USBR (1976), Mw = moment magnitude,
6. The deterministic estimates of the Site PGA are based on the attenuation relationship of
Boore, Joyner, Fumal (1997)
Landmark Consultants, Inc.
Tentative Tract No. 33085 - La Quinta, CA LCI Repoit No LP05057
as so
Nf �
,I
Highland
Redlands
8:d'-AII
San�J1
MAP OF REGIONAL FAULTS AND SEISMICITY
Big Bear
6 4 A (92)
® M5.5+
M 5.9-6.4
M 6.5 - 6.9
■ M 7.0+
33.25
Legends to Faults:
BC:
Blue Cut
BM:
Borrego Mountain
BSZ:
Brawley Seismic Zonf-
CC :
Coyote Creek
CN:
Calico -Newberry
EL
Elmore Ranch
ELS:
Elsinore
EM-C:
Emerson -Copper Min,
EP:
Eureka Peak
H:
Helendale
HS-B
Hot Springs -Buck Ridge
JV:
Johnson Valley
IM::
Imperial
M:
Morongo
E -C ML:
Mesquite Lake
NF:
North Frontal Zone
OWS:
Old Woman Springs
7.3 (92) P-B:
Pisgah -Bullion
PM
Pinto Mtn
Joshu Tier SA:
San Andreas
SG-B :
San Gorgonio -Banning
SH:
Supershilion Hills
SJ:
(47)
Jpgs
San Jacinto
(9z)
8.8 ' (48)
,§Pgngs RIVERSIDE CO.
SG-B
Palm Desert
SA
Indio
(_a Quin
SA
Project Site
\
Salton
e 2 ) Salton Ci Sea
•11725 -11700-116.75 11650-118.25 •11600 .115 r5
Copfright 1997 by Shetlon L. Stringe!- GE
Faults and Seismic Zones from Jennings (1994). Earthquakes rnoddied from Ellsworth (1990) catalog.
Figure 1. Map of Regional Faults and Seismicity
Landmark Consultants, Inc.
Tentative Tract No.33085 — La Quinta. CA LCI Report No. LP05057
However, because of the high tectonic activity and deep alluvium of the region, we cannot preclude
the potential for surface rupture on undiscovered or new faults that may underlie the site.
► Liquefaction. Liquefaction is unlikely to be a potential hazard at the site since the groundwater is
deeper than 50 feet (the maximum depth that liquefaction is known to occur).
Other Secondary Hazards.
► Landsliding. The hazard of landsliding is unlikely due to the regional planar topography. No
ancient landslides are shown on geologic maps of the region and no indications of landslides were
observed during our site investigation.
► Volcanic hazards. The site is not located in proximity to any known volcanically active area and
the risk of volcanic hazards is considered very low.
► Tsunamis, seiches, and flooding. The site does not lie near any large bodies of water, so the
threat of tsunami, seiches, or other seismically -induced flooding is unlikely.
3.4 Site Acceleration and CBC Seismic Coefficients
Site Acceleration: Deterministic horizontal peak ground accelerations (PGA) from maximum
probable earthquakes on regional faults have been estimated and are included in Table 1. Ground
motions are dependent primarily on the earthquake magnitude and distance to the seismogenic
(rupture) zone. Accelerations also are dependent upon attenuation by rock and soil deposits,
direction of rupture and type of fault; therefore, ground motions may vary considerably in the same
general area.
We have used the computer program FRISKSP (Blake, 2000) to provide a probabilistic estimate of
the site PGA using the attenuation relationship of Boore, Joyner, and Fumal (1997) Soil (310). The
PGA estimate for the project site having a 10% probability of occurrence in 50 years (return period
of 475 years) is 0.68g.
CBC Seismic Coefficients: The CBC seismic response coefficients are calculated from the near -
source factors for Seismic Zone 4. The near -source factors are based on the distance from the fault
and the seismic source type. The following table lists seismic and site coefficients (near source
factors) determined by Chapter 16 of the 2001 CBC. This site lies withift 9.7 kill of a Type A fau t
overlying S„ (srifn soil.
Landmark Consultants, Inc. Page 7
Tentative Tract No.33085 — La Quinta. CA LC1 Report No. LP05057
CBC Seismic Coefficients for Chapter 16 Seismic Provisions
Seismic
Seismic
Distance to
Near Source Factors
Seismic Coefficients
CBC Code
Soil Profile
Edition
Type
Critical
Type
Source
Na
Nv
Ca
Cv
2001
soil)
A
< 9.7 km
1.01
1.23
0.45
0.79
(stiff
Ref. Table
16-J
16-U
---
16-S
16-T
16-Q
16-R
3.5 Subsurface Soil
Subsurface soils encountered during the field exploration conducted on April 18, 2005 consist of
very loose to medium dense interbedded silty sands, sandy silts, and clayey sandy silts with near
surface silty sands. The subsurface logs (Plates B-1 through B-3) depict the stratigraphic
relationships of the various soil types.
3.6 Groundwater
Groundwater was not encountered in the borings during the time of field exploration. According to
Coachella Valley Water District (MM) readings of groundwater levels from nearby wells,
groundwater is located between depths of approximately 147 to 151 feet below the ground surface in
the vicinity of the project site. There is uncertainty in the accuracy of short-term water level
measurements, particularly in fine-grained soil. Groundwater levels may fluctuate with precipitation,
irrigation of adjacent properties, drainage, and site grading. The groundwater level noted should not
be interpreted to represent an accurate or permanent condition.
3.7 Hydroconsolidation
In arid climatic regions, granular soils have a potential to collapse upon wetting. This collapse
(hydroconsolidation) phenomenon is the result of the lubrication of soluble cements (carbonates) in
the soil matrix causing the soil to densify from its loose configuration during deposition.
Landmark Consultants, Inc. Page 8
I-entative Tract No.3 3085 — La Quinta, CA LCI Report No. LP05057
The collapse potential test indicated a slight risk of collapse upon inundation at the project site.
Therefore, building foundations are not required to include provisions for mitigating the
hydroconsolidation caused by soil saturation from landscape in•igation or broken utility lines.
3.8 Soil Infiltration Rate
A total of two (2) infiltration tests were conducted on May 19, 2005 at the proposed location for the
stormwater retention basin as shown on the Site and Exploration Plan (Plate A-2). The tests were
performed using pipes inside 6-inch diameter hand auger boreholes made to depths of approximately
3 feet below the existing ground surface, corresponding to the anticipated bottom depth of the
stormwater retention basin. The pipes were presoaked and filled with water and successive readings
of drop in water levels were made for a total elapsed time of 360 minutes, until a stabilization drop
was recorded.
A soil infiltration rate of 13.0 gallons per hour per square foot of bottom area may be used for
infiltration design. An oil/water separator should be installed at inlets to the stormwater retention
basin to prevent sealing of the basin bottom with silt and oil residues.
We recommend additional testing should be performed after the completion of rough grading
operations, to verify the soil infiltration rate.
Landmark Consultants, Inc. Page 9
Tentative Tract No.33085 — La Quinta. CA LCI Report No. LP050_57
Section 4
RECOMMENDATIONS
4.1 Site Preparation
Clearing and Grubbing_ All surface improvements, debris or vegetation including grass, trees, and
weeds on the site at the time of construction should be removed from the construction area. Root
balls should be completely excavated. Organic strippings should be hauled from the site and not
used as fill. Any trash, construction debris, concrete slabs, old pavement, landfill, and buried
obstructions such as old foundations and utility lines exposed during rough grading should be traced
to the limits of the foreign material by the grading contractor and removed under our supervision.
Any excavations resulting from site clearing should be dish -shaped to the lowest depth of
disturbance and backfilled under the observation of the geotechnical engineer's representative.
Building, Pad Preparation: The existing surface soil within the building pad/foundation areas should
be removed to 36 inches below the existing grade or 18 inches below the lowest foundation grade
(whichever is lower) extending five feet beyond all exterior wall/column lines (including adjacent
concreted areas). Exposed subgrade should be scarified to a depth of 8 inches, uniformly moisture
conditioned to f2% of optimum moisture content, and recompacted a minimum of 90% of the
maximum density determined in accordance with ASTM D1557 methods.
The native granular soil is suitable for use as compacted fill and utility trench back fil1. The native
soil should be placed in maximum 8 inch lifts (loose) and compacted to a minimum of 90% of
ASTM D1557 maximum dry density at optimum moisture ±2%.
Imported fill soil (if required) should similar to onsite soil or non -expansive, granular soil meeting
the USCS classifications of SM, SP-SM, or SW-SM with a maximum rock size of 3 inches. The
geotechnical engineer should approve imported fill soil sources before hauling material to the site.
Imported granular fill should be placed in lifts no greater than 8 inches in loose thickness and
compacted to a minimum of 90% of ASTM D1557 maximum dry density at optimum moisture ±2%.
In areas other than the building pad which are to receive area concrete slabs, the ground surface
should be scarified to 8 inches, moisture conditioned to 2% over optimum, and recompacted to a
minimurn of 90% of ASTM D1557 maximum density just prior to concrete placement.
Landmark C'onsultants. Inc. Page 10
Tentative Tract No.33085 — La Quinta. CA LCI Report No. LP05057
Trench Backfill: On -site soil free of debris, vegetation, and other deleterious matter may be suitable
for use as utility trench backfill, but may be difficult to uniformly maintain at specified moistures and
compact to the specified densities.
Backfill soil within roadways should be placed in layers not more that 6 inches in thickness and
mechanically compacted to a minimum of 90% ofthe ASTM D1557 maximum dry density except
for the top 12 inches of the trench which shall be compacted to at least 95%. Native backfill should
only be placed and compacted after encapsulating buried pipes with suitable bedding and pipe
envelope material. Pipe envelope/bedding should either be clean sand (Sand Equivalent SE>30) or
cnished rock when encountering groundwater. A geotextile filter fabric (Mirafi 140N or equivalent)
should be used to encapsulate the crushed rock to reduce the potential for in -washing of fines into the
gravel void space. Precautions should be taken in the compaction of the backfill to avoid damage to
the pipes and structures.
Moisture Control and Drainage: The moisture condition of the building pad should be maintained
during trenching and utility installation until concrete is placed or should be rewetted before
initiating delayed construction.
Adequate site drainage is essential to future performance of the project. Infiltration of excess
irrigation water and stormwaters can adversely affect the performance of the subsurface soil at the
site. Positive drainage should be maintained away from all structures (5% for 5 feet minimum across
unpaved areas) to prevent ponding and subsequent saturation of the native soil. Gutters and
downspouts may be considered as a means to convey water away from foundations. If landscape
irrigation is allowed next to the building, drip irrigation systems or lined planter boxes should be
used. Drainage should be maintained without ponding.
Observation and Density Testing All site preparation and till placement should be continuously
observed and tested by a representative of a qualified geotechnical engineering firm. Full-time
observation services during the excavation and scarification process is necessary to detect
undesirable materials or conditions and soft areas that may be encountered in the construction area.
The geotechnical firm that provides observation and testing during construction shall assume the
responsibility of "geotechnicn( engineer of retort!" and, as such, shall perform additional tests and
investigation as necessary to satisfy themselves as to the site conditions and the recommendations for
site development.
Landmark Consultants. Inc. Page 11
Tentative Tract No.33085 — La Quinta. CA LCi Report No. LP05057
Auxiliary Structures Foundation Preparation: Auxiliary structures such as free standing or retaining
walls should have the existing soil beneath the structure foundation prepared in the mariner
recommended for the building pad except the preparation needed only to extend 18 inches below and
beyond the footing.
4.2 Foundations and Settlements
Shal low spread footings and continuous wall footings are suitable to support the structures provided
they are founded on a layer of properly prepared and compacted soil as described in Section 4.1. The
foundations may be designed using an allowable soil bearing pressure of 1,500 psl: The allowable
soil pressure may be increased by 20% for each foot of embedment depth in excess of 18 inches and
by one-third for short term loads induced by winds or seismic events. The maximum allowable soil
pressure at increased embedment depths shall not exceed 2,500 psf.
All exterior and interior foundations should be embedded a minimum of 18 inches below the
building support pad or lowest adjacent final grade, whichever is deeper. Continuous wall footings
should have a minimum width of 12 inches. Spread footings should have a minimum dimension of
24 inches. Recommended concrete reinforcement and sizing for all footings should be provided by
the structural engineer.
Resistance to horizontal loads will be developed by passive earth pressure on the sides of footings
and frictional resistance developed along the bases of footings and concrete slabs. Passive resistance
to lateral earth pressure may be calculated using an equivalent fluid pressure of 300 pcf to resist
lateral loadings. The top one foot of embedment should not be considered in computing passive
resistance unless the adjacent area is confined by a slab or pavement. An allowable friction
coefficient of 0.35 may also be used at the base of the footings to resist lateral loading.
Foundation movement under the estimated static (non -seismic) loadings and static site conditions are
estimated to not exceed % inch with differential movement of about two-thirds of total movement for
the loading assumptions stated above when the subgrade preparation guidelines given above are
followed.
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Tentative Tract No.33085 — La Quinta, CA LC1 Report No. 0050-57
4.3 Slabs -On -Grade
Concrete slabs and flatwork should be a minimum of 4 inches thick. Concrete floor slabs may either
be monolithically placed with the foundation or dowelled after footing placement. The concrete
slabs may be placed on granular subgrade that has been compacted at least 90% relative compaction
(ASTM D 1557) and moistened to near optimum moisture just before the concrete placement
To provide protection against vapor or water transmission through the slabs, we recommend that the
slabs -on -grade be underlain by a layer of clean concrete sand at least 4 inches thick. To provide
additional protection against water vapor transmission through the slab in areas where vinyl or other
moisture -sensitive floor covering is planned, we recommend that a l0-mil thick impermeable plastic
membrane (visqueen) be placed at mid -height within the sand layer. The vapor barrier should be
installed in accordance with the manufacturer's instructions. We recommend that at least a 2-foot
lap be provided at the membrane edges or that the edges sealed.
Concrete slab and flatwork reinforcement should consist of chaired rebar slab reinforcement
(minimum of No. 4 bars at 18-inch centers, both horizontal directions) to resist potential forces
related to soil movement and cracking. Slab thickness and steel reinforcement are minimums only
and should be verified by the structural engineer/designer knowing the actual project loadings. All
steel components of the foundation system should be protected from corrosion by maintaining a 3-
inch minimum concrete cover of densely consolidated concrete at footings (by use of a vibrator).
The construction joint between the foundation and any mowstrips/sidewalks placed adjacent to
foundations should be sealed with a polyurethane based non -hardening sealant to prevent moisture
migration between the joint. Epoxy coated embedded steel components or permanent waterproofing
membranes placed at the exterior footing sidewall may also be used to mitigate the corrosion
potential of concrete placed in contact with native soil.
Control joints should be provided in all concrete slabs -on -grade at a maximum spacing (in feet) oft
to 3 times the slab thickness (in inches) as recommended by American Concrete Institute (ACI)
guidelines. All joints should form approximately square patterns to reduce randomly oriented
contraction cracks. Contraction joints in the slabs should be tooled at the time of the pour or sawcut
('/4 of slab depth) within 6 to 8 hours of concrete placement. Construction (cold) joints in
foundations and area flatwork should either be thickened butt joints with dowels or a thickened
keyed joint designed to resist vertical deflection at the joint. All joints in flatwork should be sealed
Landmark Consultants. Inc. Page 13
Tentative Tract No.33085 — La Quinta, CA LCI Report No. LP05057
to prevent moisture, vermin, or foreign material intrusion. Precautions should be taken to prevent
curling of slabs in this arid desert region (refer to ACI guidelines).
All independent flatwork (sidewalks, patios) should be underlain by 12 inches of moisture
conditioned and compacted soils. All flatwork should be jointed in square patterns and at
irregularities in shape at a maximum spacing of 10 feet or the least width of the sidewalk. Driveway
slabs should have a thickened edge extending a minimum of 4 inches below a 4-inch sand or
aggregate base course which should be compacted to a minimum of 90% of ASTM D 1557 maximum
density.
4.4 Concrete Mixes and Corrosivity
Selected chemical analyses for corrosivity were conducted on bulk samples of the near surface soil
from the project site (Plate C-4). The native soils have low level of sulfate ion concentration (164
ppm). Sulfate ions in high concentrations can attack the cementitious material in concrete, causing
weakening of the cement matrix and eventual deterioration by raveling.
A minimum of2,500 psi concrete of Type II Portland Cement with a maximum water/cement ratio
of 0.60 (by weight) should be used for concrete placed in contact with native soil on this project
(sitework including streets, sidewalks, driveways, patios, and other wall foundations).
The native soil has moderate level of chloride ion concentration (250 ppm). Chloride ions can cause
corrosion of reinforcing steel, anchor bolts and other buried metallic conduits. Resistivity
determinations on the soil indicate moderate potential for metal loss because of electrochemical
corrosion processes. Mitigation of the corrosion of steel can be achieved by using steel pipes coated
with epoxy corrosion inhibitors, asphaltic and epoxy coatings, cathodic protection or by
encapsulating the portion of the pipe lying above groundwater with a minimum of 3 inches of
densely consolidated concrete. No metallic pipes or conduits should be placed belowjoundations.
Foundation designs shall provide a minimum concrete cover of three (3) inches around steel
reinforcing or embedded components (anchor bolts, hold-downs, etc.) exposed to native soil or
landscape water (to 18 inches above grade). Additionally, the concrete should be thoroughly
vibrated at footings during placement to decrease the permeability of the concrete.
Landmark Consultants, Inc. Page 14
Tentative Tract No.33035 — La Quinta. CA LCI Report No. LP05057
4.5 Excavations
All site excavations should conform to CalOSHA requirements for Type C soil. The contractor is
solely responsible for the safety of workers entering trenches. Temporary excavations with depths of
4 feet or less may be cut nearly vertical for short duration. Temporary slopes should be no steeper
than 1.5:1 (horizontal: vertical). Sandy soil slopes should be kept moist. but not saturated, to reduce
the potential of raveling or sloughing.
Excavations deeper than 4 feet will require shoring or slope inclinations in conformance to
CAUOSHA regulations for Type C soil. Surcharge loads of stockpiled soil or constriction materials
should be set back from the top of the slope a minimum distance equal to the height of the slope. All
permanent slopes should not be steeper than 3:1 to reduce wind and rain erosion. Protected slopes
with ground cover may be as steep as 2:1. However, maintenance with motorized equipment may
not be possible at this inclination.
4.6 Lateral Earth Pressures
Earth retaining structures, such as retaining walls, should be designed to resist the soil pressure
imposed by the retained soil mass. Walls with granular drained backfill may be designed for an
assumed static earth pressure equivalent to that exerted by a fluid weighing 35 pcf for unrestrained
(active) conditions (able to rotate 0.1 % of wall height), and 55 pcf for restrained (at -rest) conditions.
These values should be verified at the actual wall locations during construction.
When applicable seis►nic earth pressure on walls may be assumed to exert a uniform pressure
distribution of 7.514 psf against the back of the wall, where H is the height of the backfill. The total
seismic load is assumed to act as a point load at 0.614 above the base of the wall.
Surcharge loads should be considered if loads are applied within a zone between the face of the wall
and a plane projected behind the wall 45 degrees upward from the base of the wall. The increase in
lateral earth pressure acting uniformly against the back of the wall should be taken as 50% of the
surcharge load within this zone. Areas of the retaining wall subjected to traffic loads should be
designed for a uniform surcharge load equivalent to two feet of native soil.
Landmark Consultants, Inc. Pagc 15
Tentative Tract No.33085 — La Quinta, CA LCl Report No. LP05057
Walls should be provided with backdrains to reduce the potential for the buildup of hydrostatic
pressure. The drainage system should consist of a composite HDPE drainage panel or a 2-foot wide
zone of free draining crushed rock placed adjacent to the wall and extending 2/3 the height of the
wall. The gravel should be completely enclosed in an approved filter fabric to separate the gravel
and backfill soil. A perforated pipe should be placed perforations down at the base of the permeable
material at least six inches below finished floor elevations. The pipe should be sloped to drain to an
appropriate outlet that is protected against erosion. Walls should be properly waterproofed. The
project geotechnical engineer should approve any alternative drain system.
4.7 Seismic Design
This site is located in the seismically active southern California area and the site structures are
subject to strong ground shaking due to potential fault movements along the San Andreas Fault.
Engineered design and earthquake -resistant constriction are the common solutions to increase safety
and development of seismic areas. Designs should comply with the latest edition of the CBC for
Seismic Zone 4 using the seismic coefficients given in Section 3.4 of this report. This site lies
within 9. 7 km of a Type A fault overlying S„ (stif) soil.
4.8 Pavements
Pavements should be designed according to Caltrans or other acceptable methods. Traffic indices
were not provided by the project engineer or owner; therefore, we have provided structural sections
for several traffic indices for comparative evaluation. The public agency or design engineer should
decide the appropriate traffic index for the site. Maintenance of proper drainage is necessary to
prolong the service life of the pavements. Based on the current State of California Caltrans method,
an estimated R-value of 40 for the subgrade soil and assumed traffic indices, the following table
provides our estimates for asphaltic concrete (AC) pavement sections.
Landmark Consultants. Inc. Page 16
Tentative Tract No.3 3085 — La Quinta, CA LCl Report No. LP05057
RECOMMENDED PAVEMENTS SECTIONS
R-Value of Subgrade Soil - 40 estimate(l) Dcsi n Method - CALTRANS 1990
Flexible Pavements
Traffic
Index
(assumed)
Asphaltic
Concrete
Thickness
(in.)
Aggregate
Base
Thickness
(in.)
5.0
3.0
4.5
6.0
3.5
6.0
7.0
4.5
6.5
8.0
5.0
Notes:
1 } Asphaltic concrete shall be Caltrans, Type B, 3/, inch maximum medium grading, ('/z inch for
parking areas) compacted to a minimum of 95% of the 50-blow Marshall density (ASTM
D 1559).
2) Aggregate base shall conform to Caltrans Class 2 (3/4 inch maximum), compacted to a
minimum of 95% of ASTM D 1557 maximum dry density.
3) Place pavements on 8 inches of moisture conditioned (minimum 2% above optimum) native
soil compacted to a minimum of 90% of the maximum dry density determined by ASTM
D1557.
Final recommended pavement sections may need to be based on sampling and R-Value testing
during grading operations when actual subgrade soils will be exposed.
Landmark Consultants, Inc. Page 17
Tentative Tract No.33085 — La Quinta, CA LCI Report No. LP05057
Section 5
LIMITATIONS AND ADDITIONAL SERVICES
5.1 Limitations
The recommendations and conclusions within this report are based on current information regarding
the proposed single family residential development located on the southwest corner of Beth Circle
and Madison Street, between Avenue 51 and Avenue 52 in La Quinta, California. The conclusions
and recommendations of this report are invalid if.
► Structural loads change from those stated or the structures are relocated.
► The Additional Services section of this report is not followed.
I. This report is used for adjacent or other property.
► Changes of grade or groundwater occur between the issuance of this report and
construction other than those anticipated in this report.
► Any other change that materially alters the project from that proposed at the time this
report was prepared.
Findings and recommendations in this report are based on selected points of field exploration,
geologic literature, laboratory testing, and our understanding of the proposed project. Our analysis of
data and recommendations presented herein are based on the assumption that soil conditions do not
vary significantly from those found at specific exploratory locations. Variations in soil conditions
can exist between and beyond the exploration points or groundwater elevations may change. If
detected, these conditions may require additional studies, consultation, and possible design revisions.
This report contains infor»ration that Wray be useful in the preparation of contract specifications.
However, the report is not worded is such a manner that we recommend its use as it construction
specification document without proper modification. The use of inforinatlon contained ill this
report for bidding purposes should be done at the contractor's option ititd risk.
This report was prepared according to the generally accepted geotechiucal engineeringstandards of
practice that existed in Riverside County at the time the report was prepared. No express or implied
warranties are made in connection with our services. This report should be considered invalid for
periods after two years from the report date without a review of the validity of the findings and
recommendations by our firm, because of potential changes in the Geotechnical Engineering
Standards of Practice.
Landmark Consultants. Inc. Page 18
Tentative Tract No.3308-5 — La Quinta. CA LCI Report No. LP050>7
The client has responsibility to see that all parties to the project including, designer, contractor, and
subcontractor are made aware of this entire report. The use of information contained in this report
for bidding purposes should be done at the contractor's option and risk.
5.2 Additional Services
We recommend that Landmark Consultants, Inc. be retained as the geotechnical consultant to
provide the tests and observations services during construction. If Landmark Consultants does not
provide such services then the geotechnical engineeringfrrm providimgsuch tests and observations
shall became the geotechnical engineer ojrecord and assume responsibility for the project.
The recommendations presented in this report are based on the assumption that:
► Consultation during development of design and construction documents to check that the
geotechnical recommendations are appropriate for the proposed project and that the
geotechnical recommendations are properly interpreted and incorporated into the
documents.
► Landmark Consultants will have the opportunity to review and comment on the plans and
specifications for the project prior to the issuance of such for bidding.
► Continuous observation, inspection, and testing by the geotechnical consultant of record
during site clearing, grading, excavation, placement of fills, building pad and subgrade
preparation, and backfilling of utility trenches.
► Observation of foundation excavations and reinforcing steel before concrete placement.
► Other consultation as necessary during design and construction.
We emphasize our review of the project plans and specifications to check for compatibility with our
recommendations and conclusions. Additional information concerning the scope and cost of these
services can be obtained from our office.
Landmark Consultants. Inc. Page 19
P,
AUP41
AJ
Project Site
LANIIMARK
Pi-oject No.: LP05057
NATIONAL
MONUMENT
410& A� ,4
Vicinity Map
Plate
A-1
OVA HLmrA ••1LW
LU
3
IL 1NM7 f+,n0
Proje
mow,-
1-2
" I-1 Ad�,-
Legend
Ar Approximate Boring Location (typ)
10 Approximate Infiltration Test Location (typ)
LANHMAHK
Plate
Project No.: LP05057 Site and Exploration Plan A-2
\J ...... a MaD `•►`� a:I
32 N�Jf . Gw a
M AI !
' Ylelci
-- i Mal '
MA
MnH Ip
MaH 1
u .l,
I Man t�
GbA I MaB M.iH 7 la
GbA GbA
Mop �
I Il' A Mn() C&A
(ia\
,i
GbA
4 I t Pa►
i\ Maf) AVfNtif
f Is GbA
Puma I
RU f•;
10r'0ject Site
RO �_ f. 1 .� _ •.....•r!
• t v . GbA c=.�
LANOMARK
USDA Soil Conservation Plate
Project No.: LP05057 Soil Service Map A-3
SOIL SURVEY OF
Riverside County, California
Coachella Valley Area
•rr�
United States Department of Agriculture
Soil Conservation Service
in cooperation with
University of California Agricultural Experiment
Station
66
Soil, SURVEY
1fadl,11111:
HA.
llisrrow jilt,:
Bull 1'ral1.
B11
Crb:
s D---
08to Vnrimit.
bD...
(•.•urizo:
ccc.
Vat'it:v. -
CdC, Cd E
09
C hC
C k a..
Carmut. Vilflallt
C m It, Cm I
Chuck:molla.
Ca Is, Cc 1)
cnc. Cnc
01:14.111-11a:
CpA, C p 8
C,A
CsA
F
I SDA
TA11I.E9.--E119invv?'htq
IThe syniNd < nvatir, le..ts than; memis greater than.
I. wit.-Ii A \SI I'll I
of 3
CL NIII, VL. SM S(*. C
al IiN
r;ln/l> bntt,:, I/,aru
!' \tL. I'I- \II, I. M
I I flit
Savid, 14saiiiii. -and, gravo-11). -Alld
sm. sl. sm
11 111
SI, ,:\I
111 39
39 fill
Very -tmiv t„.ar ,an.1
1) 60
Gnivell v sand
IS
0 111
Sagill .
:4.\I. SM
111 60
I;f;tvf.11 v
SI, SM
11 oil)
UfIbIlIv -atid
S11. sil SM
1) 610
Hill. S1611.1
SM
0 1 It Salid. fillr �alld �-\l
-;klllly villy I"mok
I Iw, (-..%I ka
) crav(tw- :atjily I,imji %-,.tv
GM,
-,-11�
0.11. fi 111111ll4.
:'arldv lisnin.
25 fill
Vs-ry strivOlY smi-I, vs-ry visbill.-v gawl
4'.1l' till. (;%%'. S"
to 12
C.'I'Id% fu;,
1 9i
11•ry gt %V1.11% fill,- �;llvk k:4111. V0.1. v , "1.14
(.\I, (;I, (i.M
CA)
V--r ' v grave 11%' ruin, v, ry -uhtily sm,41
W, S11, klllo"
I I Of
ti:lwl. fi-14. 'mid
s M. I'll NM
I fit I
I
hike
s M
I fit
Filks. -widY Iml.11
.SM, M I.
14) .101
smid. (113, -w.d
SM. -I, .:Nl
ill Q
I-wiltiv fill, -.tlitl
sm, sm s(
It 641
to IM
V.tmll.b.
A 2, A I
A 4. A I,
A A I
A I
A 2, A 3
A I
A - I
A-2
1{1VERSIDE COUN 1'Y. CALIFORNIA
6
prole rlics (llld rhissiJira ons
Al,s.rnce c,f :u) rntry tw-ans
clnta w,-n, nflt
1•stimatrill
Pores -Wags-
1".,j 11U Ii'
`ll'Yr IIIIIh wr
I Illllbl
I'11.1L I"
I1I
Pet
—
1
1'r1
i
:, :11
1►:, Ilxl
!11) 1fill
.;:, 711
11 111
1115 1lAI
!III Ifill
71) 911
a:1 1 i
:.i 411
b 1:r
1) _(I
!N) IOII I
I
110 to.",
10 ♦U
:{+I iI1
I-i :{II
\I' Ill
11 I
tI.".-IOfI
till 1(lU
.111 7.;
I.i :III
\I'
11
IIAI
S:; I111)
I
I:,
\P
11
100 I
ill I IN)
:{,; 7.;
i :I11
\ P
III :U I
1N) Ilxl
\(1 100
II) ;0 I
t) lIr
\1,
11 III
.111 fill
:I,;—:10
•:1) :1;,
1► :,
\I'
Ili :10
I
Siff 1110
k11 1011
4ll .i0 I
0 111
\ I'
1 I) 10
K5-11xl
;dl So
1
I
\I'
1)
4:1 11111
WI fill) I
50 741
5 (:i
\11
I 11
S.1 1011
51) 75 ?
:1 :111
1) III
\11
1; 30
%:, -I11)1
:dl SII
'J :+11
11 I11
\11
II I:r
till [(Ill
�;, 11NI
\I'
(00
T.i Ills
i
50 so I
I
,; :{0 j
�
\ P
I� to
4:1 :,:/
.11► .;n
:f11 :{:1
IJ :.1u
•::1 :IJ
:, 13
i fill
1.; fill i
:IU .50
l i Li
i
i :tll I
1.; '.a
\ P ;I
fill
V) 60
:311 50
1 i :{:. 1
II ;
I
\ I'
.{II
'111 61/ I
ID .i0
:1i 1�.
:U :fll
�11I :{II
\P
fill
I•i fill I
{II :+11
I:r I:.
5 :ill I
I
15 '::,
\ I' •;
.; Iil
•1:; fill
:ill .;I1
I; :i:1
)
I1
11
f1111
loo
11:1 \0
N P
11
IIN!
loll)
li:, \I)
.'ll V.
\11
11
fllll
IIIII
711 \,i
Ifl :,.i
111 21)
11
I1111
11111
U
1
f tl(1
I
I
11 II I
f 1 \1I I
I :1 111
I
N I'
GS
soil, SURVEY
. oil narne and
hail syltilmil
G6B....
GbA, Gb B, GcA...
GdA..... . .
GCA, GIA......
Gravel pits And 111lmp.4 G P.
1111``lerinl:
IcA, IfA.. ......
ImC" IoCe.
1nttn•ria) part
(-sullied hind part.
India'
Is, It_
l.ithie Turrilr..-m utent.:
L R?:
Lithie Turripvammi-nts hart
Ituck uutrrop part.
Mlvoula:
Matt, MaD, McB___..
Niland:
Ne8__.
NbB -__
t►mstmt:
O mD...
Or r:
(Imstott part..._-_.
Itock otet. rup part.
Itiverwneh:
RA.
Rock outcrop:
RO.
R 1r:
Rock mtta•rup part.
I.ithic'furrips:ttutncttts
Rubble land:
RU.
Salton
Sb -...
Depth
h
In
TABLE ().—I:ngineereng propertied
C.L��+if icalt ion
I'lll{ta'll AASIrro
I.Ot+tllV fine lintld ..
SNI
\ 2. A -•I
Ntrnti7i+•tl L, .air. - ,I I to silty ehty lu:uu....
M11.
\ .1
r;ne sand'.
Mtl.. sm
\ -1
stlatifird I- 'IA to salty clay Imull
M11.
\ .1
line sand.,
SMI,
Stratified I',\ smid I,) Silty clay butlll-
MI 1.
\
Silty 4-111s ; ,:n..
('I.
\ 6, .1 7
Sill )onto
MI I.
\ 4
Stral►fied lunlny aunt) to >'ilty cl:+y loom
Ml 1.
.1 4
0-60 ' Silty cll►y.
0 130 i Silty clny.-
t'll
<'11
i
It II1 I)III. randy lualn... _. `N1, NIL
ery fine ;Addy lo:un, +ill local, handy loam.. MI I.
Ii la 1 ery fin•• +allt(v Want.. MI I.
Its 4,11 1,•ry fine sandy Ilium, silt Liam, sandy Mll.
h,am.
o -1 sand, 1,)ntll), Nand, fine stand SM1, yl'-SMI
•1 t'nwPathercd bedrock. -
0-60 (
line annd.....
W-21 !
sand..
21 1141 I
Silty elav
0 23 i
sand. -
'3 6t1
Silly elay
0 10
Comm. eendV lo:lrtt.....
lu
Weathered hedruck
It 11)
Gravelly fille anntly loam.
to
Weatllt•red hrdr"ck.
Snood, loamy rand, fine %and
t'na•ea►hered I►-druek.
Fier santly loam. .
('Iny, <ilty day, silty clay )"mill
silty rlay )onto._
C'Iny, )silty day, silty clay lumen__. -
�11
CL, (•11
14MI, 'Al' SMt
CI., (111
SMI
SMI
,MI, S1, sm
A•-7
A-7
A-4
A - •1
A-4
A-1
A-2, A-3
A -2
A .1, A-2
A -7
A3,A2
A -7
A 2, A •1
A-2.A•1
A'2, A.1
RIVED-SIVE COUNTY, CALIFORNIA
%nd classifications —Continued
Prteelllage mel'Ing
Fragments sieve nuM )er—
>3 -- inches — 1 � _ �0 _ 40 I 2011
Pet
100
IINI
loll
100
IINI
100
I
Ion
I(X0
M,
WE
75-100
100
W()
75.85
iE
100
95 -100
95 100
!15-101)
11N)
I(N)
1(N)
.15 100
95 1 M
95-1(N)
9.1 11N1
95-100
95 -1(K)
50-100
SO-100
70-R0
RO--100
70-85
RO.100
704M
M -100
95-100
90-100
SO. • I On
100
7() . M)
Rn loll
85 115
80 100
50-80
05- 80
,0 65
05 100
50 65
95 1U0
60.70
55 -70
50 80
70-R5
110 -100
05-100
90-100
'� 5-50
W-60
4n 155
5n-60
40 55
50-60
M -•95
70-90
50 6o
W) 95
W) 95
411 5h
50 •70
50 65
50 70
5-35
20 :15
30-50
2.1 441
40 50
75 95
85 95
75 95
Liquid
limit
Pet
10 -30
20 30
25 45
20-30
50 70
50 74)
15 31)
15 30
15 -:If)
15 30
45 70
45-70
15-25
15 25
15 31)
35 60
35.60
35-60
69
1'llutirty
index
NP
Nil
NP-5
NP
N P-5
NP
10-20
N P-5
NP
25-45
25 -15
Nl'-5
N P-5
N 1'-5
N P-S
NP
N 1'
Nil
2545
NP
25-45
N P-5
Nil
5-10
25.35
15-35
25 35
70 SOR. SURVEY
4111t1►nr and
1r4,1,111
1SDA haturr
nrop �ynlitt.l
In
l�ofx�bn:
SoD.
t1 I:1
('..hld} :r:aud
13 1:11
Very 81u11y real., \•rt\' . nl.l.l\' r:, h.I, t •fc
ff:ivrll%
SpE---------
a Ix
S11111Y r111d
I.. fin
11vy stun}' ralul, Very „.hf.IV S.lud, V.•rn
gmvell\ F:ltllt.
Torrinrthrrlls:
TO a:
Torriorthrntr part,
n tA1
:,riable.
Itock outerr.11 pmt.
'1'u uut;:1
frc.........
1
IV4.11Y Illattly-:11141-
t s fl. -
"tltl. filtr
TA1t1.F 1D.—Effigint ring prnpertica
('I:m4firatit.n
1 nOMI I .% k.-AI O
r f' %I .1 I
tale I:J1, rl' r�l 1 I
A
S M A .'
gat A J, A-1
' NI' is nonplastn .
''Phis mopping unit 1.: n ado, up A t%c•a or more dominant kinds of w1il, tie •. mapping unit .14meriplion f1.r the composition and
I►tdlaeior of the whole mapping unft.
moisture density, tlu,chanic•al allaly�e.i. liquid limit and
plasticity index.
In the wiei h,i, -tie n::lea. ur compaction test. :I sa inple
of the soil ni alt-ri.11 is voill acted SI'Vetal times with it
C"llsta nt ('1•mpat'tive eftiul•1, flach time at :1 successively
higher ilit,lstllrl• cmitent. The moisture content ill -
creases until the aptinium moisture content is rearhed.
After that thy density decreasu's with increase in
moisture content. The highest density obtained in the
compaction test is tern1Wl WUtxi munl densitY.r.
Alnisture-(lensity data are importan! in c•onstrnction,
for as a rule, optimum stability is 140:0111'd if till' soil is
conipacled to ahoul the maximuni dry density w•ltyll it
is at approximately the optimum moi,talrc cr.ntent.
Phv:heel rl►1rl rhr'roiral prrrperlirs
II'.1bly 1 1 sh1•', 1, -i iml:lted Values fill. several soil
vilaracteristic•S :Intl ft-;Mures that all'et•t behavior of
sc»ls it, engineering, Ilse> These usttilt.•Itus :Ire givell
for each 111:1jor horizrul. it till' depths indicated. in the
typi.':11 pe11on tit vach soil. The vstilcafws are baked oil
now t11.::ter\al It.tr-- ;and ,if (l^t data for these and shnllar
soil Z.
I', r•ow ahilit y i; c'stinulted on the Wis of known to-
lati,in�,hips aniong the soil characteristics obSyrved in
the lielrl. particularly soil Structure. poro�ity. and gra-
dation of texture, 1.hal influence the downward 11loVe-
nient of waler in the suit. The eatimate; are for vertical
water movement when the soil is saturated. Nut con-
sideroat in ill(- estimates is lateral seelnuie or such
tr:11 soil fi-Allres .Is plov.-palls nlid surface crusts.
I'yr111..I:,!lily of the soil is .111 inipnrlallt factor to be
vonsitll-r1+d in planning : ild designing drainage sys-
tcrlis, in evaluating the potelltiall 4 sails for septic
taulk sl.tymS and othyr wastv rti:tlo.-:fl sySlenls, au1+1 in
many other a';pects of knd ust, .11111 nialulgenlent.
Aroilcahlr welter r-opnriltl is rated on the basis of
soil char;wteristics that influence the ability of the
,�.•il to) 11.o11 walel. and toa!(e it available to plants.
lnt!►In•tanl 11a1-m-terisl i1 , are content of Organic Inat-
ter. soil wore, and t:1.11 :.Iructure, fihallow-rooted
platltS air, not liliely tr1 u,1, the availably water from
the deppe! oil horizons.:1\ailable water capacity isaln
inipr►l-tanl factor in Ow c h"i,•y of phints or crops to be
anown and in the dc-11;rn (if irrigation systems.
soil rrrartion is expreS.,4t-d as a range in fill Values.
The r•antsy in Ill[ of vas 11 m:l.irlr horizon is based on
m:uly field rhecic:<. For many Soils, the Values have
beetl Verified by laboratory analyses. Soil reaction is
itnllorlault in Selecting the Crops, ornamental plants.
cur otter plants to he grower ; in evaluating soil ;ilnend-
ments for fertility and stabilization; and in evaluating
the Corrosivily of soil:;.
tillli►titl/ is expressell as the electrical conductivity
of the .attrl.ation extract. in nlillinihos per centimeter
at .-'-I degrees C. E!ziimates :u-e baked on field and
laboratory mcasurenlents at representative sites of the
nonirrigaled s11i1S. The salinity of individual irl•igated
lielcls is all'eeted by the quality of the irr•i„ation water
anti by true frytµlency of water application. Hence,
the R:lhnHy of hWi%idual lit -ids -:in differ greatly from
thy Value given in t:lhlc' 11. Salinity atl'ects the suit-
ability of .1 S I for trot, I,rollmcl ion. its Stability When
Used as a construction material, and its potential to
corrode metal and c1►ncrete.
Sh►•inli-atr'rll loots a al dvpewls nwinly upon the
amount alai kind of clay it, the soil. 1.:tboraltory nle:l-
su►•r•mynlS of the swelling of undisturbed clods were
for main) soils. For others th1' Swelling was
eslilliated nil the basis of the kind and amount of clay
in the soil anti om imutAurements of sindiar soils. The
size of the load and the magnitude of tilt' change in
'lnrl �lfr,sifiruliolt.►—t'onlinued
1-nigre nts
3 --r-- -
inI 11ra 1
I
Net I -
I1 :iU
.'.ti - I
U1 1;c1
Ill lit)
141 Iilt
111VF t-`+IDE 1'0t'NTV, t'ALIFOI(\IA
P,•n•entlogr u)*rilig
rir`Yt' gill I +r r—
1 u tU
GO -i5
ao dU
MR
i s 100
:10 7.'t
: 11111
:nil moisture colitr`lil also inflnencl• tilt' sa•cilini, of
;ails. Shrinkinir and off -Dine soils t•an rallst-
china-1. to Itllildinj, fmillolal inn.'. bllscnuvrlt walls. roads.
and t)ther strill-tilres milers -;pli •ial de�lt!11� are tlsed.
A iligh sprint•:-moo-1.11 pot1•nt;,ll indicates th:lt slrecial
I le�igll and milivil expel:-e nlav Ill- retluirefd if the
palltlell 11;11 of tla• loll %: ill Ilut t.lit- rill e 1:1rge %•olUllle
l; sl; n1 ,'Orl'„str.it 11011 :1iII; 11. pot ellIUll so11-Illdllred
t•1!I-fillcaI aelloll Coal Ihs olves Iol' weal."lls tl`1rn ited
sttfel el. coat retr. 'I'},e noc of core'•• -•ion of uncoated
Ai -el is related to srtil 11wi.,4111-t•, partielf-size. Ilktribil-
tioll, total acithl%and ell•1•tl•it':ll Loll( U. IiCItV 14 this
.Ilil lnateri;Il. T) It• raft• 01' tnrrn..if,tl of cnnerete i,
lla-wd rllainl%- on the sul"Af. content, fext`irI% ;Ill,l avill-
itY of tile` :tad. 1t1'f lt't't!" me: ksure, flit s'wel of Illurt'
rI'slsl:;n( enllurvie I i'I ' 1''rlld Itl' flip inlize (Lml;t1'1'
ru.,wdlilll' fl'on) 111' ��t1'1'tI,' 111. 1'Ii.Ylatetl ;1tv'1 intcr-
-t%wling •"!i 11n111!,d;ll'Ie: t.l' <tlil htrl'iTr 11 I� nL)i'k r11F-
('1`1)til)le it) t'n1'rtr.Ctntl 01.11, all ill'1;Iliatinit Ihai is
entire;% %, ilhill Itne kiud of ,)II or %cithill Ilne soil
horixna
E.i•rlK... ir Irtrinl:� at'r L.'e,i II) pro'ditt the erv,IibiIit%
-
of :I soil alld its ill I-clatioll to
;pecitit- kiml,' of land i and Ireatnll'it The soil
erocliicilit%- furlor (i•, , i�z :f iw asure of the su.—;,vwo ilit v
of the -:oil to erositln by %%-aler. Soils having, the
K vaIllt'. aI-I' Ilse most vrodll►lt'. K %altles laiwo, frojill
11.11) 1,, 1 1 i• . f ilu:lte a111111il i; lu.: Iles• ;I(l't•. the
K %ahl oil i nu)difit'd I)}• t.lctol'< i•epr•est-ntitlr
plant rot.',. r. );r:-Ile :11111 It'li th of Slope. immagenu'nt
pl':v'tlee.S, slid t'lilliate. The soil-It.ss I,)i,•1':IIlvv f:tl•tu)
IT) is tilt- ma zimun► rate of soil erositin, %%'hether
frtlm rainfali I,r -'oil Itlo%%•ili , lhat (•:ui ot•r'ur• %•, ithoill
refducin;t clop 1)rodlI;t1011 or I•IliroulliellU l Ilualily.
25 III
ito :`: �
LiI all
15 -•L:
6.1
Liquid
Ptu'l wit y
intfl-s
it
The 1•:tte Is eXpreSSed ill loll- Ill <ttll to<S pet- ;MT Ile%.
ye.11•.
Wind I rl,d;hililt/ gr•olip., are lllade till of soils that
have .imilar properlies Illat affect thoir resistance to)
soil hItltt•ink if cultivated. The I'l-Im ►s ltl•e Used if,
predict the stwovplibilit%. of Soil to blowing alld the
;Illlount of sail In.t :1; a re -till of 11111winl;. Soils are
. rotlped :u•voriiinit to the fonmvimf clistinct.ions:
S;uuls, coal -se sands, line s;Ulds, and %•er% line sands.
nit -se soils an. extreni(`i> ,'r,t,lil►le, -n vol,g'etation is
difficult to establish. They ard. grelleril:.v nclt suitable
for crop.
l,oallt%• ::ands, lant> fide sands, and loanly %•erg• fine
Sall ls. Tht•se soit< are %'ery highly crodible. lint eloh:
4•:111 he i,,'r1 vil if intrilsi%e mtastires to control soil
itlut%•i11;Care usrll.
Sa1111%loalll;, rnal'.-W SiMli%• ltlaills, line sa1111%' lualll<.
:Intl t•erc line san11•.- lovlls. The..e .oils are higIll}- vold-
li,le. Iflit ernp., r:u1 he �rro1Cll It Illtvnsl%•e measures t-,
1 utlt rol soil bilm ilig, :.r•` used.
t'alcaret)Us loallt%• soils that :it-(, less thall :d.i percelit
Ala}• and Vlore than percellt finch• divid(od calcium
carhonale. 'I'lo'se .nil• ar•e t,--rotlible, but Crop.; can }II
Vro%cll if il,ten"ki. to control soil II!t,%%•ill"
:11'e IISf•rl.
silt%• c1a\s, d;ly Imlills, and silt%• clan loam.
111:11 al•e nlfll'e thall :15 perevili day. 'I'lle';e soils 111'1•
moderately- erodible. but Crop: Can lie Krowil if 111ea-
111't to Control ;Ilil hlo%Cllli( :11.1' used.
Lonilly .Ilids t lat art' les: thall Is pel•c•ent 4+1 :old
less than perrent firtel}• divided calciunl c;u•bottate
;old Sand clad- ';o:ltll!4 :tivl sancll• clays that :u•e less
thall I', percent litlt-l% di%'ided calcium cal-hollaie• 'l'hI'•I
Soils an. slightl}• ermlillle, bill crolf< (all be grown if
i1lll'f' to e1,1111•ol ;I,il bin%rlt.j' Ill-e 11<1•Il.
l.tlanl%• :ails that are Is to a:, 1►el•cel►t clay and Ie;s
te
AIL
AVLI
AM
ProjeCi'SAVLUUL
i
Reference: USGS Topographic Map Site Coordinates
La Quinta, CA Quadrangle Lat: 33.675N
Scale 1:25,000 Long: 116.253W
LAN14111K
oP,N>uS.rC .-n--. Plate
Project No.: LP05057 Topographic Map A-4
CLIENT Core Homes. LLC METHOD OF DRILLING
CME 55 w/autohammer
PROJECT Tentative
Tract No 33085 - La Quinta. CA DATE OBSERVED 04/18/05
LOCATION: See Site and Exploration Plan
LOGGED BY. TB
LOG OF BORING B-1
o
w a
s g w
SHLLI 1 OF 1
w y r
w v
u a
x
DESCRIPTION OF MATERIAL
w F
H Na
W o
a
o
SURFACE ELEV +i-
aa
U
Cr
`5
QoU
SILTY SAND (SM) Olive brown, moist, fine grained
5
11
75 90.0
SILTY SAND/SANDY SILT (SM/ML) Olive brown, loose,
moist, trace of clay
10
❑14
27.8 81 3
medium dense. wet
15
3
CLAYEY SANDY SILT (ML) Olive brown, very loose.
35.5 79.6 9`.
wet.
20
2
25
Il
SILTY SAND (SM) Olive brown. medium dense, moist,
}`
_
fine grained
30-
14
_I
35
N 15
CLAYEY SANDY SILT (ML) Olive brown, medium
401
I
12
dense, moist. soil mottling
uI
45
16
SILTY SAND (SM) Olive brown, medium dense, moist,
fine grained.
50
22
End of Boring at 51 5 ft
55
No Groundwater Encountered
Blows not corrected for overburden pressure, sampler
size or increase drive energy for automatic hammers.
Project No:
LANUMARK
Plate
LP05057
-
B-1
d OBEMBEiSBE Company
CLIENT
Core Homes, LLC METHOD OF DRILLING
CME 55 w/autohammer
PROJECT:
Tentative Tract No. 33085 - La Quinla, CA
DATE OBSERVED
04/18/05
LOCATION: See Site and Exploration Plan
LOGGED BY TB
LOG OF BORING B-2
Z
x
W
Z
o
�
f
o a SIIF`T 1 Or 1
WiR 3
is
4
W DESCRIPTION OF MATERIAL
2
oa a
d
5 a
o
ao CrZo
q
g
SURFACE ELEV. +I-
u
a
SILTY SAND (SM): Olive brown, moist, fine grained.
I- 5
15
20
-25
M8 loose, damp 46 852
1 12 medium dense 6.3 844
8 loose
End of Boring at 13 5 fl
No Groundwater Encountered
"Blows not corrected for overburden pressure, sampler
size or increase drive energy
for
orautomatiic hammers
Project No: LANDMARK Plate
LP05057 - - - • • B-2
:. oxtin�eF•seF c„„i,...,y
0
CLIENT
Core Homes, LLC METHOD OF DRILLING
CME 55 w/autohammer
PROJECT
Tentative Tract No 33085 - La Quinta, CA
DATE OBSERVED 04/18/05
LOCATION: See Site and Exploration Plan
C
LOGGED BY TB
LOG OF BORING B-3
a
o
o
' a
Q i
~ Z SHEET 1 )f 1
O W
Z
oo_
W 2 y <
z
F
a LL J
o w DESCRIPTION OF MATERIAL
�wz ZX o
o N a
a
; Y
° o
—1
00 s io a
5
u W
m a SURFACE ELEV +l
" o '"
SILTY SAND (SM) Olive brown moist. fine grained.
5
12 medium dense. damp
10 �
i\� 5 loose
1
15 \11 medium dense
.2 20
25
-30-
35
-40 End of Boring at 16 5 ft
No Groundwater Encountered
"Blows not corrected for overburden pressure. sampler
size or increase drive energy for automatic hammers.
Project No: LANDMARK
LP05057 =• •
., neF.erBesar ro,,N,.,.ry
74 847
Plate
B-3
4
DEFINITION OF TERMS
PRIMARY DIVISIONS
SYMBOLS
SECONDARY DIVISIONS
Gravels
0 0.<
o e GW
Well graded gravels, gravel -sand mixtures, little or no fines
Clean
More than half gravels (less than
GP
.
Poorly graded gravels, or gravel -sand mixtures, little or no fines
of _5% fines)
coarse fraction
' N.
njt�l GM
Silly gravels, gravel -sand -silt mixtures, non -plastic fines
Coarse grained soils Is Gravel
Yll'11
larger than No with fines
or 4
GC
Clayey gravels, gravel -sand -clay mixtures, plastic fines
More than hall of 4 sieve
��
_
material is larger Sands I Chen sands (less
SW
••±itiii
Well graded sands, gravelly sands, little or no fines
than 5% fines)
T SP
Poorly graded sands or gravelly sends, little or no fines
than No 200 sieve More than half
of coarse
SM
Silty sands, sand -silt mixtures, non -plastic fines
fraction Sands
1i1L
is smaller than with Ones
lff, SC
Clayey sands, sand -clay mixtures, plastic fines
No 4 sieve i
Silts and clays
J11 11. MIL
Inorganic sills. clayey silts with slight plasticity
CL
Inorganic clays of low to medium plasticity, gravely, sandy, or Man clays
Fine grained sods Liquid limit is
less than 50%
More than hall of
OL
I;I;I;I-
Organic silts and organic clays of low plasticity
material is smaller Silts and clays
MH
Inorganic sills. micaceous or diatomaceous silty sails, elastic sills
CH
Inorganic days of high plasticity, fat clays
than No 200 sieve Liquid limit is
more than 50'S
OH
i
Organic days of medium to high plasticity, organic silts
Highly organic sods
jrMn PT
AVIV___.
Peat and other highly organic soils
GRAIN SIZES
Sills and Clays Sand
Gravel Cobbles Boulders
Fine Medium Coarse
Fine Coarse
200 4
10 4
3/4' X 12
US Standard Series
Sieve
Clear Square Openings
Clays 8 Plastic Sills
S_ Uenglh "
81ow3/111 '
Sands, Gravels, etc
Blowsrft '
Very Soft
0-0 25
0-2
Very Loose
04
Soft
0 25-0 5
2-4
Loose
4-10
Firm
0 5-1 0
4.8
Medium Dense
10-30
Stiff
1 0-2-0
8-16
Dense
30-50 1
Very Stiff
2.0.4.0
16-32
Very Dense
Over 50
Hard
Over 4.0
Over 32
Number of blows of 140lb hammer falling 30 inches to drive a 2 inch O D (1 3/8 in I D ) split spoon (ASTM D1586)
Unconfined compressive strength in tonsfs f as determined by laboratory testing or approximated by the Standard
Penetration Test (ASTM D1586). Pocket Penetrometer, Torvane, or visual observation
Type of Samples
11 Ring Sample N Standard Penetration Test I Shelby Tube 0 Bulk (Bag) Sample
Drilling Notes
1 Sampling and Blow Counts
Ring Sampler . Number of blows per foot of a 140 lb hammer falling 30 inches
Standard Penetration Test - Number of blows per fool
Shelby Tube • Three (3) Inch nominal diameter tube hydraulically pushed
2 P P = Pocket Penetrometer (tons/s I)
3 NR = No recovery
4 GWT = = Ground Water Table observed 4? specified time-
I■ANI)MARK
n ORFlMBE�SBE Conrµai.y
Project No: LP05057
Key to Logs
Plate
B-4
0
1
-2
r -3
Af
COLLAPSE POTENTIAL TEST (ASTM D5333)
Po
Water Colla se
p
Added ------- J Potential = 0.4',4. (Slight)
Silty Sand (SM)
B-3@50ft
1
Pressure (ksf)
10
100
Results of Test: Initial
Final
Dry Density, pcf 84.7
92.6
Water Content. % 7 4
29 7
Void Ratio, e 0.954
0 786
Saturation, % 21
100
1 LANDMARK
Geo Engineers and Geologists
a D"E"AME,SHE Compa,,v
Project No: LP05057
Remolded Collapse Potential
Test Results
Plate
C-1
t1111H1111
p 105
95
85 L
0
\ Client: Core Homes, LLC
Project: Tentative Tract No 33085
Project No: LP05057
Date: 05/18/05
SUMMARY OF TEST RESULTS_
Description: Silty Sand (SM)
\ Sample Location: B-3 @ 0-5 ft.
Test Method ASTM D1557 A
�\ Maximum Dry
Density (pcf) 101 0
\ Optimum Moisture
Content (%): 16.5
Curves of 100%
saturation for
specific gravity
equal to:
2.75
2.70
2.65
5 10 15 20 25
Moisture Content (%)
3(
LANDUARK
Goo -Engineers and Geologists
OBE/MBE/SHE Cnnipn•IV Plate
Project No: LP05057 Moisture Density Relationship C-2
LANDMARK CONSULTANTS, INC.
CLIENT:
Core Homes, LLC
PROJECT:
Tentative Tract No. 33085 - La
Quinta, CA
JOB NO:
LP05057 DATE:
05/19/05
DIRECT SHEAR TEST - REMOLDED (ASTM D3080)
SAMPLE LOCATION:
B-3 @ 5.0 ft
SAMPLE DESCRIPTION:
Silly Sand (SM)
Specimen: 1
2
3 Avg.
Shear Stress vs Rel. Displacement E1
Moisture Content, W 7.4
7.4
7.4 7.4
1.0
Dry Density, pcf: 84.7
84.7
84.7 84.7
1
c
Saturation, W 21
21
21
0.8
2
Moisture Content, W 36.4
35.1
35.8
v
3
Dry Density, pcf: 84.3
85.7
84.9
N 0.6
Saturation, W 100
100
1 CO
d
in
Normal Stress, ksf: 0.52
1.07
1.63
0.4
Peak Shear Stress, ksf: 0.32
0.70
0.94
Residual Shear Stress, ksf- 0.29
0.60
0.86
0.2
Deformation Rate, in./min. 0.010
0.010
0.010
0.01
Residual
Peak
0
5 10 15
Angle of Internal Friction, deg.:
29
27
Relative Displacement (%)
Cohesion, ksf:
0.05
0.03
4
N 3
o�
DIRECT SHEAR TEST RESULTS
0'
0 1 2 3 4 5 6 7 8
Normal Stress (ksf)
LANUMARK
Goo -Engineers and Geologists
,W1, AlfisBE Direct Shear Plate
Project No: LP05057 Test Results C-3
LANDMARK CONSULTANTS, INC.
CLIENT: Core Homes, LLC
PROJECT: Tentative Tract No. 33085 - La Quinta, CA
JOB NO: LP05057
DATE: 05/19/05
CHEMICAL ANALYSES
Boring:
B-1
CalTrans
Sample Depth, ft:
0-5
Method
pH.
7.15
643
Resistivity (ohm -cm):
8,000
643
Chloride (CI), ppm:
250
422
Sulfate (SO4), ppm:
164
417
General Guidelines for Soil Corro
Material Chemical
Amount in
Affect—ed- Agent
So Pffl)—
Concrete Soluble
0 -1000
Sulfates
1000 - 2000
2000 - 20000
> 20000
Normal Soluble
Grade Chlorides
Steel
Normal Resistivity
Grade
Steel
0 - 200
200 - 700
700 - 1500
> 1500
1-1000
1000-2000
2000-10,000
10.000+
Degree of
Cornvity
Low
Moderate
Severe
Very Severe
Low
Moderate
Severe
Very Severe
Very Severe
Severe
Moderate
Low
GeologistsLANIJUARK
Geo-Engineers, and
. OBE/MBE/SBE Conrpeny Selected Chemical Plate
Project No: LP05057 Analyses Results C-4
SUMMARY OF INFILTRATION TESTING
Client:
Core Homes, LLC
Date Excavated:
04/18/05
Project:
Tentative Tract No
33085 - La Quinta,CA Technician:
JB
.lob No.:
LP05057
Location:
See Site and Exploration Plan
Date:
05/19/05
Soil Type:
Silty Sand (SM)
Test Hole No.:
i-1
Total Depth of Test Hole:
37'
Total
Reading Time Elapsed
No. Time Interval Time
(min) _(min)
1 15 15
2
15 30
3
15
45
4
15
60
5
30
90
6
30
120
7
fi0
180
8
fi0
240
9
60
300
10
61711
360
Initial
Final
Fall
Water
Water
in Water Stabilized Rate
Level
Level
Level Drop
(in.)
(in.)
(in.) (min/in) , al/hr/sft
13.00
23.25
10.25
2.00
12.50
10.50
0.00
10.75
10.75
0.00
18.25
18.25
0.00
27.00 27.00
3.00
35.25
32.25
1.00
_
38.00
37.00
1.00
38.00
37.00
1.00
38.00
37.00
1.00
38.00
37.00 1.62 23.07
SUMMARY OF INFILTRATION TESTING
Client:
Core Homes, LLC
Date Excavated:
04/18/05
Project:
Tentative Tract No. 33085 -
La Quinta,CA Technician:
JB
Job No.:
LP05057
Location:
See Site and Exploration Plan
Date:
05/19/05
Soil Type:
Silty Sand (SM)
Test Hole No.:
I-2
Total Depth of Test Hole:
3'
Reading
No.
_4
5
6
7
8
9
10
Total
Initial
Final
Fall
Time
Elapsed
Water
Water
in Water Stabilized Rate
Time Interval
Time
Level
Level
Level Drop
(min)
(min)
(in.)
(in.)
(in.) (min/in) gal/hr/sft
15
15
8.50
15.00
6.50
15
30
15
45
15
60
30
90
30
120
60 180
60 240
60 300
60 360
1.00
6.25
5.25
1.00 6.75
5.75
1.00
6.50
5.50
1.00
12.50
11.50
1.00
13.00
12.00
1.00
23.25
22.25
1.00
20.25
19.25
1.00
21.50
20.50
1.00
24.25
23.25 2.82 13.29
REFERENCES
Arango I., 1996, Magnitude Scaling Factors for Soil Liquefaction Evaluations: ASCE
Geotechnical Journal, Vol. 122, No. 11.
Bartlett, Steven F. and Youd, T. Leslie, 1995, Empirical Prediction of Liquefaction -
Induced Lateral Spread: ASCE Geotechnical Journal, Vol. 121, No. 4.
Blake, T. F., 1989-1996, FRISKSP - A computer program for the probabilistic estimation
of seismic hazard using faults as earthquake sources.
Bolt, B. A., 1974, Duration of Strong Motion: Proceedings 5th World Conference on
Earthquake Engineering, Rome, Italy, June 1974.
Boore, D. M., Joyner, W. B., and Fumal, T. E., 1994, Estimation of response spectra and
peak accelerations from western North American earthquakes: U.S. Geological
Survey Open File Reports 94-127 and 93-509.
Building Seismic Safety Council (BSSC), 1991, NEHRP recommended provisions for the
development of seismic regulations of new buildings, Parts 1, 2 and Maps:
FEMA 222, January 1992
California Division of Mines and Geology (CDMG), 1996, California Fault Parameters:
available at http://www.consrv.ca.gov/dmg/shezp/fltindex.html.
Ellsworth, W. L., 1990, Earthquake History, 1769-1989 in: The San Andreas Fault
System, California: U.S. Geological Survey Professional Paper 1515, 283 p.
International Conference of Building Officials (ICBO), 1994, Uniform Building Code,
1994 Edition.
International Conference of Building Officials (ICBO), 1997, Uniform Building Code,
1997 Edition.
Jennings, C. W., 1994, Fault activity map of California and Adjacent Areas: California
Division of Mines and Geology, DMG Geologic Map No. 6.
Jones, L. and Hauksson, E., 1994, Review of potential earthquake sources in Southern
California: Applied Technology Council, Proceedings of ATC 35-1.
Joyner, W. B. and Boore, D. M., 1988, Measurements, characterization, and prediction of
strong ground motion: ASCE Geotechnical Special Pub. No. 20.
Mualchin, L. and Jones, A. L., 1992, Peak acceleration from maximum credible
earthquakes in California (Rock and Stiff Soil Sites): California Division of
Mines and Geology, DMG Open File Report 92-01.
Naeim, F. and Anderson, J. C., 1993, Classification and evaluation of earthquake records
for design: Earthquake Engineering Research Institute, NEHRP Report.
National Research Council, Committee of Earthquake Engineering, 1985, Liquefaction of
Soils during Earthquakes: National Academy Press, Washington, D.C.
Porcella, R. L., Matthiesen, R. B., and Maley, R. P., 1982, Strong -motion data recorded
in the United States: U.S. Geological Survey Professional Paper 1254, p. 289-
318.
Robertson, P. K., 1996, Soil Liquefaction and its evaluation based on SPT and CPT: in
unpublished paper presented at 1996 NCEER Liquefaction Workshop
Seed, Harry B., Idriss, I. M., and Arango I., 1983, Evaluation of liquefaction potential
using field performance data: ASCE Geotechnical Journal, Vol. 109, No. 3.
Seed, Harry B., et al, 1985, Influence of SPT Procedures in Soil Liquefaction Resistance
Evaluations: ASCE Geotechnical Journal, Vol. 113, No. 8.
Sharp, R. V., 1989, Personal communication, USGS, Menlo Park, CA.
Stringer, S. L., 1996, EQFAULT.WK4, A computer program for the estimation of
deterministic site acceleration.
Stringer, S. L. 1996, LIQUEFY.WK4, A computer program for the Empirical Prediction
of Earthquake -Induced Liquefaction Potential.
Structural Engineers Association of California (SEAOC), 1990, Recommended lateral
force requirements and commentary.
Tokimatsu, K. and Seed H. B., 1987, Evaluation of settlements in sands due to
earthquake shaking: ASCE Geotechnical Journal, v. 113, no. 8.
U.S. Geological Survey (USGS), 1990, The San Andreas Fault System, California,
Professional Paper 1515.
U.S. Geological Survey (USGS), 1996, National Seismic Hazard Maps: available at
http://gldage.er.usgs.gov
Wallace, R. E., 1990, The San Andreas Fault System, California: U.S. Geological
Survey Professional Paper 1515, 283 p.
Working Group on California Earthquake Probabilities (WGCEP), 1988, Probabilities of
large earthquakes occurring in California on the San Andreas Fault: U.S.
Geological Survey Open -File Report 88-398.
Working Group on California Earthquake Probabilities (WGCEP), 1992, Future seismic
hazards in southern California, Phase I Report: California Division of Mines and
Geology.
Working Group on California Earthquake Probabilities (WGCEP), 1995, Seismic hazards
in southern California, Probable Earthquakes, 1994-2014, Phase II Report:
Southern California Earthquake Center.
Youd, T. Leslie and Garris, C. T., 1995, Liquefaction induced ground surface disruption:
ASCE Geotechnical Journal, Vol. 121, No. 11.