360527 (ELEC) Geotechnical ReportREPORT OF GEOTECHNICAL INVESTIGATION
PROPOSED OFFICE AND RETAIL BUILDING
DESERT CLUB DRIVE AND LA FONDA DRIVE
LA QUINTA, CALIFORNIA
PREPARED FOR:
MR. D.F. COHEN
C/O MR. JIM FETRIDGE
73 - 965 HIGHWAY 111
PALM DESERT, CALIFORNIA 92206
PREPARED BY:
SOUTHERN CALIFORNIA SOIL AND TESTING, INC.
74-831 VELIE WAY
PALM DESERT, CALIFORNIA 92260
.1
S O U T H E R- N C A L I F O R N I A S❑
I L
AND T" E
S T I N
G, I N C.
6280 RIVERDALE ST. SAN DIEGO, CALIF. 92120 • .TELE 280-4321 •
P.O. BOX 20627 SAN DIEGO,
CALIF. 92120
7 4- 8 3 1 V E- L I E W A Y P A L M D E S E! R T,
C A L I F.
9 2 2 6 0 •
T E L E
3 4 6- 1 0 7 6
6 7 8 E N T E R P R I S E S T. E S C 0 N D I D O,
C A L I F.
9 2 0 2 5 •
T E L E
7 4 6- 4 5 4 4
March 31, 1986
Mr. D. F. Cohen SCST 8631034
c/o Mr. Jim Fetridge Report No. 1
73-965 Highway 111
Palm Desert, California 92260
Subject: Report of Geotechnical Investigation, Proposed
Office and Retail Building, Northwest Corner of
Desert Club Drive and La Fonda Drive, La Quinta,
California.
Gentlemen:
In accordance with your request, we are transmitting herewith
our report on the subject investigation. In summary, this
investigation revealed that relatively soft soils are present
on the site, and that overexcavation and compaction will be
required on this project.
We appreciate the opportunity to be of service on this project.
If you have any questions, please call this office at your
convenience.
Respectfully submitted,
SOUTHERN CALIFORNIA SOIL AND TESTING, INC.
Glenn S. Fraser, RCE # 39132
GSF/AHJ/ds
cc: -(5) Submitted
(1) SCST, San Diego
S O U T H E R N C A L I F O R N I A . =S ❑ 1 L A N D T E S T I N G, 1 N C.
tTABLE OF CONTENTS
' Page
Introduction and Project Description...........................1
Project Scope.................................................1
' Site Conditions.._-- .... oo-o ... o ... oo.-o___2
Site Description., ... o-oo-oo ........... ..... o ... oo ... 000.2
General Geology and Subsurface Conditions......... .......... 2
' Geologic Setting and Soil Description.............. ... o2
Groundwater...........................................3
Tectonic Setting._ ...... oo ...... � ..
'
Seismicity... ....::....... ......................:.....3
Geologic Hazards.......... ... .... ...4
Conclusions and Recommendations...............................5
' General Discussion......:..................................5
Site Grading... ....................5
Site Preparation_ ...
Pavement Subgrade......................................6
' ImportSoils.......................................6
Site Drainage,...---- ...
Earthwork............
.......................6
Earthwork............................................6
Foundations.................................................6
' General................................................6
Reinforcement..........................................7
Lateral Resistance.---, ..........................7
Concrete Slabs -On -Grade....-.......... ...... 0000.00..7
Settlement Characteristics... -
Expansive Characteristics_— ...
' Foundation and Grading Plan Review......... ...... 7
Limitations..... oo.00.... ......g
Review, Observation and Testing...... .... 8
' Uniformity of Conditions........ .......................
........8
Change in Scope..0000 ........8
Time Limitations., ..... oo ....... 000._ ........
Professional Standard......................................9
' Client's Responsibility., ... 000.00..00 ... oo .....
Field Exploration........... _ ...............................9
Laboratory Testing Program, ... oo ......
' ATTACHMENTS
' Plate 1 Plot Plan
Plate 2 Unified Soil Classification Chart
' Plates 3 and 4 Trench Logs
' Plate 5 Direct Shear Tests and Compaction Tests
APPENDIX.
' Recommended Grading Specifications - Special Provisions
4S- _r..
S U T H E R N C A L I F R N I A SOIL AND T %E S T I N G, I N C
62BID RIVERDALE ST. SAN DIEGO, CALIF. 92120 • TELE 280-4321 • P.O. BOX 20627 SAN DIEGO, CALIF. 92120
74-831 VELI E WAY PALM DESERT, CALIF. 92260 • TELE 346-1078
6 7 8 E N T E R P R I S E S T. E S C O N D I D 0, C A L I F. 9 2 0 2 5 • T E L E 7 4 6- 4 5 4 4
GEOTECHNICAL INVESTIGATION
PROPOSED OFFICE AND RETAIL BUILDING
DESERT CLUB DRIVE AND LA FONDA DRIVE
LA QUINTA, CALIFORNIA
INTRODUCTION AND PROJECT DESCRIPTION
This report presents the results of our geotechnical
'= investigation, for the proposed Office and Retail Building, to
be located in the City of La Quinta, California. The site
location is shown on the vicinity.map provided as Figure No. 1.
From a conversation with the civil engineer, Mr. Brian
Gottlieb, itis our understanding that the project will consist
of a 2 -story wood -frame office building. Continuous and
isolated footings will be used as a foundation system. The
maximum loads. on the footings will be 2.2 kips per linear foot
and 12 kips for the continuous and isolated footings,
respectively.' The site configuration and approximate locations
of our trenches are shown on Plate No. 1 of this report.
PROJECT SCOPE
This investigation consisted of: surface reconnaissance,
subsurface explorations, obtaining representative samples,
laboratory testing, analysis of the field and laboratory data,
research of available geologic literature pertaining to the
site,.and preparation of this report. Specifically, the intent
of our analysis was to:
a) Explore the subsurface conditions to the depths
influenced by the proposed construction.
b) Evaluate, by laboratory tests, the pertinent
engineering properties of the various strata
which will influence the development, including
their bearing capacities, expansive
characteristics and settlement potential. .
S O U T H E R N C A L I F O R N I A S 0 1 L A N D T E S T I N G, I N C.
Mari Reference: U. S. G. S. 7.5 Minute Quadrangle
La Qui nta, California, 1959. ( Photo Revised 1980.)
N
Pump,_:..
i s
Scale: 1" _ 2000'
SOUTHERN CALIFORNIA VICINITY MAP
�'- SOIL A TESTING, INC. BY: MN DATE: 03/25/86
00 >
f
JOB NUMBER: 8631034 Figure No. 1
SCST 8631034 March 31, 1986 Page Two
c) Define the general geology at the
possible geologic hazards which
effect on the site development.
site, including
could have an
d) Develop soil engineering criteria for site
gradirng.
e) Detexhine.potential construction difficulties and
provide recommendations concerning these
problems.
f) Recommend an appropriate foundation system for
the type of structure anticipated and develop
soil engineering criteria for the recommended
design.
SITE CONDITIONS
SITE DESCRIPTION: The project site is a rectangular shaped
parcel of land located on the northwest corner of the
intersection of La Fonda Avenue and Desert Club Drive in the
City of La Quinta, California. The site consists of an area of
approximately 12,500 square feet which is bounded on the north
by an alley and on the west by a General Telephone station.
Existing topography consists of a relatively flat area with a
maximum relief of less than one foot. Since the site is
slightly recessed below its adjacent boundaries, there is poor
to no water drainage away from the subject area. Vegetation
consists of a light to moderate growth of typical desert
grasses and shrubs with two trees at the eastern portion of the
site. No structures or apparent recent site developments were
noted on the site.
GENERAL GEOLOGY AND SUBSURFACE CONDITIONS
GEOLOGIC SETTING AND SOIL DESCRIPTION: In general, the La
Quinta area is located in the Coachella Valley, on an alluvial
plain, situated between two northerly ridges of the Santa Rosa
Mountains. La Quinta is overlapped with sediments from three
different depositional environments. The area contains remnant
lacustrine deposits from the ancient Lake Coahuila, fluvial
deposits from the outwash of the Santa Rosa Mountains and
aeolian deposits from the ongoing dune activity. Crystalline
bedrock of the Southern California Batholith underlies the area
at depth. The near surface soils which were encountered in our
explo.vatory-trenches include lacustrine. deposits consisting
largely of silts and fine grained sandy silts. The soils
SCSI 8631034 March 31, 1986 Page. Three
encountered in our trenches consisted of silts.and sandy silts
in a wet to. moist condition and very soft to soft in
' consistency. More detailed descriptions of the soils
encountered are presented on. Plate Nos. 3 and 4.
GROUNDWATER: At the time of our exploration, no groundwater
was encountered within 13 feet of existing grade. No
groundwater related problems are anticipated either during or
' after construction.
TECTONIC SETTING: The subject site is located between the San
Andreas Fault Zone and the San Jacinto Fault Zone, two of the
' known major active fault zones in the Southern California area.
The San Andreas Fault Zone is approximately 8 miles to the
northeast and the San Jacinto Fault Zone is approximately
' 18 miles to the southwest, but no faults are located in the
immediate vicinity of the site. In addition, two unnamed
faults have been mapped approximately 2.5 miles and 3.5 miles
southwest of the site. These faults are believed to be
' inactive.
SEISMICITY: Both the San Andreas Fault Zone and the San
Jacinto Fault Zone are classified as active fault zones.
Beca use this project site is closer to the San Andreas Fault
Zone than the San Jacinto Fault Zone, the former should be used
' as the "design fault."
The San Andreas Fault Zone is generally considered to have two
major branches in the vicinity of the subject site. The two
'branches are the Mission Creek Fault and the Banning Fault,
both of which are .classified as active branches. The San
Andreas Fault Zone is the largest and most studied fault zone
' in California, so much seismic information is available. The
seismicity of the Mission Creek and Banning branches of the San
Andreas Fault -Zone has been studied in the area near the
project site. -The historical seismicity of the study area,
from 1932 to 1972, and the projected number of events per 100
years is summarized in the following table adapted from the
Riverside County Seismic Safety Report (1976).
SCST 8631034 March 31, 1986 Page Four
1
Earthquake Magnitude Number of Events Number of Events
' (Richter) (1932-1972) (100 -Year Interval)
2.0 - 2.4 12 29.3
2.5 - 2.9 81 197.6
' 3.0 - 3.4 .164 400.0
3.5 - 3.9 60 146.3
4.0 - 4.4 19 46.3
' 4.5 - 4.9 5 12.2
5.0 - 5.4 2 4.9
5.5 - 5.9 0 0.0
' 6.0 -'6.4 0 0.0
6.5 - 6.9 1 2.4
GEOLOGIC HAZARDS
' The most likely geologic hazard to affect the site is
groundshaking due to movement along the San Andreas Fault Zone
or to a lesser degree, movement along the San Jacinto Fault
' Zone. Relative groundshaking hazard zones have been developed
in Riverside County by dividing the county into five zones
based on soil types and five zones based on the distance from
' causative faults. The distance zonations were chosen
arbitrarily and are defined in the technical report of the
Riverside County Seismic Safety Report (1976) so that Zone I
includes ground accelerations'for average site conditions up to
' that taken into account in the 1973 Edition of the Uniform
Building Code with each successive zone representing a multiple
of that acceleration. The project site is in Distance Zone
' III, and in Soil Type Zone B (alluvium in thin to intermediate
thickness: '100-2,000 feet thick).
' Recurrence intervals and magnitudes of earthquakes along the
San Andreas Fault Zone. are given in the following table as
taken from the Riverside County Seismic Safety Report (1976).
' Earthquake Magnitude Recurrence Interval (years)
8.0 Maximum Credible
7.5 200-500
7.0 100-200
6.5 50-100
1
1
SCSI 8631034
March 31, 1986
Page Five
The project planned for the subject site is assigned to Use
Category D (Normal -High Risk) as defined by the Riverside
' County Seismic Safety Report so that the design earthquake
recommended is the 7.0 event on the San Andreas Fault Zone.
According to the table of Generalized Characteristics of
' Expected Earthquakes that is presented in the Riverside County
Seismic Safety Report, maximum ground acceleration at the'site
should be considered to be as high as 0.46 g. Predominant
period of groundshaking and duration of "strong" shaking should
be considered to be 0.1 to 0.3 seconds and 10 to 20 seconds
respectively.
It should be recognized that the Southern California region is
an area of moderate to high seismic risk and that it is not
considered feasible to make structures totally resistant to
' seismic related hazards. The design acceleration should be
determined by the structural consultant and be reflective of
the type of structure proposed.
' Due to the geologic and geomorphic setting of the site, other
potential geologic hazards such as tsunamis, seiches,
liquefaction, or landslides should be considered to be
' negligible or nonexistent.
CONCLUSIONS AND RECOMMENDATIONS
GENERAL DISCUSSION
Most of the site is underlain by very soft to soft alluvial
deposits. These soils are considered unsuitable, in their
present condition, for the support of settlement sensitive
improvements and will require remedial grading in the form of
removal and recompaction. The recommendations of this report
assume that• existing elevations will not be increased by more
than 3 feet. In this case, the loads due to new fill will be
minor.
SITE GRADING
SITE PREPARATION: Site preparation should begin with the
removal of vegetation and other unsuitable materials. The
soils should then be overexcavated to a depth of either 1.5B or
1.OB below the bottom of the continuous and isolated footings,
respectively. B equals the footing width. The excavated soils
may be stockpiled on site for future use. The soils exposed at
the base of these excavations should then be thoroughly
moisture conditioned to at least 2% over optimum and
SCST 8631034
March 31, 1986
Page Six
densified to a minimum of 90% relative compaction to a depth of
12 inches. The stockpiled soils may then be replaced in eight
inch lifts,�and moisture conditioned and compacted as indicated
above. The horizontal limits of these recommendations should
include the area -5 feet outside of the building perimeter.
PAVEMENT SUBGRADE: The soils beneath the proposed paving areas
should be overexcavated to a depth of 12 inches, and the upper
12 inches of exposed soil should be scarified, moisture
conditioned to at least 2% above the optimum moisture content,
and compacted to at least 90% of the maximum d'ry density as
determined in accordance with ASTM D-1557-78, Method A or C.
The excavated soil should be replaced as uniformly compacted
fill.
' IMPORT SOILS: Imported fill, if required, should consist of
clean, non -detrimentally expansive soils (expansion index less
than 20) and should be approved by the soils engineer prior to
' its delivery to the site. In addition, the imported fill
should have a minimum "R" Value of 50 and minimum shear
strength parameters of 0 = 300 and C = 50 psf.
' SITE DRAINAGE: Water should not be allowed to pond adjacent to
footings. The site should be graded and maintained such that
surface drainage is directed away from the structure and the
' top of slopes into swales or other controlled drainage devices.
EARTHWORK: All earthwork and grading contemplated for site
' preparation should be accomplished in accordance with the
attached Recommended Grading Specifications and Special
Provisions. All special site preparation recommendations
presented in the sections above will supersede those in the
standard Recommended Grading Specifications. All embankments,
structural fill and fill should be compacted to a minimum of
90% at slightly over optimum moisture content. Utility trench
' backfill within '5 feet of the proposed structure and beneath
asphalt pavements should -be compacted to at least 90% of its
maximum dry density. The maximum dry density of each soil type
' should be determined in accordance with ASTM D-1557, Method A
or C. A representative of Southern California Soil and Testing
should be present to observe and test all reworked excavation
bottoms, and all soils that are placed.
FOUNDATIONS
' GENERAL: With the loading conditions as indicated in
report, it is our opinion that a shallow foundation system
consisting of continuous and isolated footings may be
this
used.
' SCST 8631034 March 31, 1986 Page Seven
All continuous .and isolated footings should bear at least 12
and 18 inches below lowest adjacent finished grade and contain
minimum widths of 12 and 18 inches, respectively. These
footings should be designed for an allowable soil bearing
' pressure of 2.0 kips per square foot. This bearing capacity
may be increased by one-third for wind and/or seismic loading.
REINFORCEMENT: It is recommended that minimum reinforcement in
' the continuous footings consist of at least 2 continuous No. 4
reinforcing bars, one located near the top of each footing and
one near the bottom. This reinforcement is 'based on soil
' characteristics and is not intended to be in lieu of
reinforcement necessary to satisfy structural considerations.
LATERAL RESISTANCE: Resistance to lateral loads may be
' provided by friction at the base of the footing and by passive
pressure against the adjacent soil. For concrete footings on
compacted soil, a coefficient of friction of 0.30 may be used.
' For calculating passive pressure, an equivalent fluid unit
weight of 250 pounds per cubic foot may be used. Passive
pressure should not exceed 1,500 pounds per square foot. When
' combining frictional and passive resistance, the latter should
be reduced by one-third.
CONCRETE SLABS -ON -GRADE: Concrete s.labs-on-grade should have a
' minimum thickness of 4 inches and be reinforced with a 6"x6"-
W1.4xW1.4 (6"x6"-10/10) welded wire fabric throughout. For
optimum efficiency, the wire fabric should be placed near the
' center of the slab. A 2 -inch thick layer of clean poorly
graded coarse sand should be placed under the slab.
SETTLEMENT CHARACTERISTICS: The anticipated total and/or
differential settlements for the structure may be considered to
.be within tolerable limits provided the recommendations
presented in this report are followed.
' EXPANSIVE CHARACTERISTICS: Laboratory testing revealed that
the expansive potential of the anticipated prevailing
' foundation soils (within 3 feet from finish grade) is low.
The recommendations contained in this report are reflective of
this condition.
' FOUNDATION AND GRADING PLAN REVIEW: The foundation and grading
plans should be submitted to this office for review to
ascertain that the assumptions utilized in the preparation of
this report are valid and that its recommendations are
implemented.
SCST 8631034 March 31, 1986 Page Eight
LIMITATIONS
REVIEW, OBSERVATION AND TESTING
The recommendations presented in this report are contingent
upon our review of final plans and specifications. The soil
engineer and engineering geologist should review and verify the
compliance of the final grading plan with this report and with
Chapter 70 of the Uniform Building Code.
It is recommended that Southern California Soil and Testing,
Inc. be retained to provide continuous soil engineering
services during the earthwork operations. This is to observe
compliance with the design concepts, specifications and
recommendations and to allow for design changes in the event
that subsurface conditions differ from those anticipated prior
to start of construction.
UNIFORMITY OP CONDITIONS
The recommendations and opinions expressed in this report
reflect our best.estimate of the project requirements based on
an evaluation of the subsurface soil conditions encountered at
the subsurface exploration locations and the assumption that
the soil conditions do not deviate appreciably from those
encountered. It should be recognized that the performance of
the foundations and/or cut and fill slopes may be influenced by
undisclosed or unforeseen variations in the soil conditions
that may occur in the intermediate and unexplored areas. Any
unusual conditions not covered in this report that may be
encountered during site development should be brought to the
attention of the soils engineer so that he may make
modifications if necessary.
CHANGE IN SCOPE
This office should be advised of any changes in the project
scope of proposed site grading so that it may be determined if
the recommendations contained herein are valid. This should be
verified in writing or modified bya written addendum.
TIME LIMITATIONS
The findings of this report are valid as of this date. Changes
in the condition of a property can, however, occur with the
passage of time, whether they be due to natural processes or
the work of man on this or adjacent properties. In addition,
changes in the State -of -the -Art and/or government codes may
SCST 8631034
March 31, 1986
Page Nine
occur. Due to such changes, the findings of this report may be
invalidated wholly or in part by changes beyond our control.
Therefore, this report'should not be relied upon after a period
of two years without a review by us verifying the validity of
the conclusions and recommendations.
PROFESSIONAL STANDARD
In the performance of our professional services, we comply with
' the standard of care and skill ordinarily exercised under
similar circumstances by members of our profession currently
practicing under similar conditions and in the same locality.
' The client recognizes that subsurface conditions may vary from
those encountered at the locations where our borings, surveys,
and explorations are made, and that our data, interpretations,
and recommendations are based solely on the information
' obtained by us. We will be responsible for those data,
interpretations, and recommendations, but shall not be
responsible for the interpretations by others of the
information developed. Our services consist of professional
consultation' and observation only, and no warranty, express or
implied, is made or intended in connection with the work
performed by us or by the . proposal for consulting or other
services or by the furnishing of oral or written reports or
findings.
• CLIENT'S RESPONSIBILITY
It is the responsibility of Nr. D.F. Cohen or his
' representatives to ensure that the information and
recommendations contained herein. are brought to the attention
of the engineer and architect for the project and incorporated
into the project's plans and specifications. It is further
their responsibility to take the necessary measures to insure
that the contractor and his subcontractors carry out such
recommendations during construction.
FIELD EXPLORATION
' Two subsurface explorations were made at the locations
indicated on the attached Plate No. 1 on March 11, 1986. These
explorations consisted of trenches extended by means of a
backhoe. The field work was conducted under the observation of
our engineering geology personnel.
' The explorations were carefully logged when made. These logs
are presented on the following Plate Nos. 3 and 4. The soils
are described in accordance with the Unified Soils
SCST 8631034 March 31, 1986 Page Ten
1
' Classification System as illustrated on the attached simplified
chart on .Plate - No. 2. In addition, a verbal textural
description, the wet color, the apparent moisture and the
' density or consistency are provided. The density of granular
soils is given as either very loose, loose, medium dense,
dense, or very dense. The consistency of silts or clays is
' given as either very soft, soft, medium. stiff, stiff,very
stiff, or hard.
' Disturbed samples of representative on-site soils were obtained
and returned to the laboratory for testing.
' LABORATORY TESTING PROGRAM
Laboratory tests were performed in accordance with the
' generally accepted American Society for Testing and Materials
(ASTM) test methods or suggested procedures. A brief
.description of the tests performed is presented below:
' A. MOISTURE -DENSITY: Field moisture content and dry
density were determined following the field
investigation. This information was an aid to
classification and permitted recognition of
variations in material consistency with depth.
The dry weight is determined in pounds per cubic
' foot, and the field moisture content is
determined as a percentage of the soil's dry
weight. The results are summarized in the trench
logs.
B. CLASSIFICATION: Field classifications were
verified in the laboratory by visual examination.
The final soil classifications are in accordance
with the Unified Soil Classification System.
' C. DIRECT SHEAR TEST: Direct shear tests were
performed to determine the failure envelope based
on yield shear strength of remolded specimens.
The shear box was designed to accommodate a
' sample having a diameter of 2.375 inches and a
height of 1.0 inch. Samples were tested at
different vertical loads and at saturated
' moisture content. The shear stress was applied
at a constant rate of strain of approximately
0.05 inches per minute. The results of these
' tests are presented on Plate No. 5.
SCST
8631034 March 31, 1986 Page Eleven
D.
COMPACTION TEST: The maximum dry density and
optimum moisture content of typical soil was
'
determined in the laboratory in accordance with
ASTM Standard Test Method D-1557-78, Method A.
The results of these tests are summarized on the
attached Plate No. 5.
E.
GRAIN SIZE DISTRIBUTION: Representative samples
of the native soil were passed through a No. 200
sieve. The results of these tests are presented
below:
'
Trench No. Percent Passing
& Depth (ft) No. 200 Sieve Soil Description
.T-1 @ 2' 71.6 Fine sandy SILT
T-2 @ 3' 94.7 SILT w/trace clay
F.
EXPANSION INDEX TEST: An expansion test, in
accordance with U.B.C. Standard 29-2 was
performed on typical on-site surface soil in
order to determine its expansion potential. The
results are presented below:
'.
Trench No. & Expansion Expansion
Soil Type Depth (ft.) Index Potential
'
SILT T-2 @ 3' 36 Low
G.
CHEMICAL ANALYSIS: A soil sample is being
analyzed to determine the soluble sulphate
'
content. The results of this test will be
1
presented under a separate cover.
DESERT CLUB DRIVE
T-2 -w.
6Wn TRENCH LOCATION
SOUTHERN CALIFORNIA
SOIL & TE$TING,INC.
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BY: MH DATE: 3/26/86
JOB NUMBER:8631034 PLATE 1
11
SUBSURFACE " EXPLORATION LEGEND
UNIFIED SOIL CLASSIFICATION CHART
SOIL DESCRIPTION GROUP SYMBOL
I. COARSE GRAINED, more than half
of material is larger than
No. 200 sieve size.
GRAVELS CLEAN GRAVELS GW
ore than half of
coarse fraction is
larger than No. 4 GP
sieve size but
smaller than 3".
GRAVELS WITH FINES GM
(Appreciable amount
of fines) GC
SANDS CLEAN SANDS SW
More than half of
coarse fraction is SP
smaller than No. 4
sieve size.
SANDS WITH FINES SM
(Appreciable amount
of fines) SC
II. FINE GRAINED, more than
half of material is smaller
than No. 200 sieve size.
SILTS AND CLAYS ML
Liquid Limit CL
less than 50
SILTS AND CLAYS
Liquid Limit
greater than 50
OL
MH
CH
OH
HIGHLY ORGANIC SOILS PT
�- — Water level at time of excavation
or as indicated
US — Undisturbed, driven ring sample
or tube sample
TYPICAL NAMES
Well graded gravels, gravel -
sand mixtures, little or no
fines.
Poorly graded gravels, gravel
sand mixtures, little or no
fines.
Silty gravels, poorly graded
gravel -sand -silt mixtures.
Clayey gravels, poorly
graded gravel -sand, clay
mixtures.
Well graded sand, gravelly
sands, little 4r no fines.'
Poorly graded sands, gravelly
sands, little or no fines.
Silty sands, poorly graded
sand and silty mixtures.
Clayey sands, poorly graded
sand and clay mixtures.
Inorganic silts and very
fine sands, rock flour, sandy
silt or clayey -silt -sand
mixtures with slight plas-
ticity.
Inorganic clays of low to
medium plasticity, gravelly
clays, sandy clays, silty
clays, lean clays.
Organic silts and organic
silty clays or low plasticity.
Inorganic silts, micaceous
or diatomaceous fine sandy
or silty soils, elastic
silts.
Inorganic clays of high
plasticity, fat clays.
Organic clays of medium
to high plasticity.
Peat and other highly
organic soils.
CK — Undisturbed chunk sample
BG — Bulk sample
SP — Standard penetration sample
SOUTHERN CALIFORNIA
SOIL A TESTING,INC. By: GSF DATE: 3/31/86
JOB NUMBER: 8631034 Plate 2
w
DIRECT SHEAR TEST RESULTS
SAMPLE
DESCRIPTION
angle of
Internal
friction (0)
cohesion
intercept
(psf)
T-1 @ 2.0'
Tan fine sandy SILT (remolded to 90%)
30
100
T-2 @ 1..0'
Tan SILT with a trace of clay.(remolded to
105.6
16.5
90%)
30
100
MAXIMUM DENSITY and OPTIMUM MOISTURE CONTENT
ASTM D -1557-7R METHODS_
SAMPLE
DESCRIPTION
maximum
density
(pcf)
optimum
moisture
content
T-1 @ 2.0'
Tan fine sandy SILT
108.2
15.8
T-2 @ 1.0'
Tan SILT with a trace of clay
105.6
16.5
SOUTHIERN CALIFORNIA
SOIL b TESTING. INC.
BY GSF
JOB NO. 8631034
DATE 3/31/86
Plate 5
PROPOSED OFFICE AND RETAIL BUILDING
DESERT CLUB DRIVE AND LA FONDA DRIVE
LA QUINTA, CALIFORNIA %.
RECOMMENDED GRADING SPECIFICATIONS - GENERAL PROVISIONS
GENERAL INTENT
The intent of these specifications is to establish procedures
for clearing, compacting natural ground, preparing areas to be
filled, and placing and compacting fill soils to the lines and
grades shown on the accepted plans. The recommendations
contained in the preliminary geotechnical investigation report
and/or the attached Special Provisions are a part of the
Recommended Grading Specifications and shall supersede the
provisions contained hereinafter in the case of conflict.
These specifications shall.only be used in conjunction with the
geotechnical report for which they are a part. No deviation
'from these specifications will be allowed, except where
specified in the geotechnical report or in other written
communication signed by the Soil Engineer.
OBSERVATION AND TESTING
Southern California Soil and Testing, Inc., shall be retained
as the Soil Engineer to observe and test the earthwork in
accordance with these specifications. It will be necessary that
the Soil.Engineer of his representative provide adequate
observations so that he may provide an opinion that the work
was or was not accomplished as specified. It shall be the
responsibility of the contragtor to assist the soil engineer
and to keep him apprised of work schedules, changes, and new
information and data so that he may provide these opinions. In
the event that any unusual conditions not covered by the
special provisions or preliminary soil report are encountered
during the grading operations, the Soil Engineer shall be
contacted for further recommendations.
' If in the opinion of the Soil Engineer, substandard conditions
are encountered, such as: questionable or unsuitable soil,
unacceptable moisture content, inadequate compaction, adverse
' weather, etc., construction would be stopped until the
conditions are remedied or corrected or he shall recommend
rejection of this work.
Test methods used to determine the.degree of compaction should
be performed in accordance with the following American Society
for Testing and Materials test methods:
SCST 8631034 March 31, 1986 Appendix, Page 2
' Maximum Density & Optimum Moisture Contegt - ASTM D-1557-
78.
Density of Soil In -Place - ASTM D-1556-64 or ASTM D 2922.
' All densities shall be expressed in terms of Relative
Compaction .as 'determined by the foregoing ASTM testing
procedures.
PREPARATION OF AREAS TO RECEIVE FILL
All vegetation, brush and debris derived from clearing
operations shall be removed, and legally disposed of. All
areas disturbed by site grading should be left in a neat and
finished appearance, free from unsightly debris.
After clearing or benching, the natural ground in areas to be
filled shall be scarified to a depth of 6 inches for the
minimum degree of compaction in the Special Provisions or the
recommendation contained in the preliminary geotechnical
report. All loose soils in excess of 6 inches thick should be
removed to firm natural ground which is defined as natural
soils which possesses an in-situ density of at least 90% of its
maximum dry density.
When the slope of the natural ground receiving fill exceeds 20%
( 5 horizontal units to 1 vertical unit) , the original ground
shall be stepped or benched. Benches shall be cut to a firm
competent soil condition. The lower bench shall be at least 10
feet wide or 1 1/2 times the equipment width whichever is
greater, and shall be sloped back into the hillside at a
gradient of not less that two (2) percent. All other benches
should be at least 6 feet wide. The horizontal portion of each
bench shall be compacted prior to receiving fill as specified
hereinbefore for compacted natural ground. Ground slopes
flatter than 20% shall be benched when considered necessary by
the Soil Engineer.
Any abandoned structures encountered during grading operations
must be totally removed. All underground utilities to be
abandoned beneath any proposed structure should be removed from
within 10 feet of the structure and properly capped off. The
resulting depressions from the above described procedures
should be backfilled with acceptable soil that is compacted to
the requirements of the Soil Engineer. This includes, but is
not limited to, septic tanks, fuel tanks, sewer lines or leach
lines, storm drains, and water lines. Any buried structures or
utilities not to be abandoned should be brought to the
attention of the Soil Engineer, so that he may determine if any
SCST 8631034 March 31, 1986 Appendix, Page 3
special recommendations will be necessary.
All water wells which will be abandoned should be backfilled
' and capped in accordance to the requirements set forth by the
Soil Engineer. The top of the cap should be at least 4 feet
below finish grade or 3 feet below the bottom of footing
whichever is greater. The type of cap will depend on the
' diameter of the well and should be determined by the.Soil
Engineer and/or a qualified Structural Engineer.
FILL MATERIAL
' Materials to be placed in the fill shall be approved by the
Soil Engineer and shall be free of vegetable matter and other
deleterious substances. Granular soil shall contain ' sufficient fine material to fill the voids. The definition and
disposition of oversized rocks, expansive and/or detrimental
soils are covered in the geotechnical report or special
provisions: Expansive soils, soils of poor gradation, or soils
with low strength characteristics may be thoroughly mixed with
other soils to provide satisfactory fill material, but only
with the explicit consent of the Soil Engineer. Any import
' material shall be approved by the Soil Engineer before being
brought to the.site.
' PLACING AND COMPACTION OF FILL
' Approved fill material shall be placed in areas prepared to
receive fill in layers not to exceed 6 inches in compacted
thickness. Each layer shall have a uniform moisture content in
' the range that will allow the compaction effort to be
efficiently applied to achieve the specified degree of
compaction. Each layer shall be uniformly compacted to a
' minimum specified degree of compaction with equipment of
adequate size to economically compact the layer. Compaction
equipment should either be specifically designed for soil
compaction or of -proven reliability. The minimum degree of
compaction to be achieved is specified in either the Special
Provisions or the recommendations contained in the preliminary
geotechnical report.
When the structural fill material includes rocks no rocks will
be allowed to nest and all voids must be carefully filled with
' soil such that the minimum degree of compaction recommended in
the Special Provisions is achieved. The maximum size and
spacing of rock permitted in structural fills and in non-
SCST 8631034 March 31, 1986 Appendix, Page 4
structural fills is discussed in the geotec4nical report, when
applicable.
Field observation and compaction tests to estimate the degree
' of compaction of the fill will be taken by the Soil engineer or
his representative. The location and frequency of the tests
shall be at the Soil Engineer's discretion. When the
' compaction test indicates that a particular layer is less than
the required degree of compaction, the layer shall be reworked
to the satisfaction of the Soil Engineer and until the desired
' relative.compaction has been obtained.
Fill slopes shall be compacted by means of sheepsfoot rollers
or other suitable equipment. compaction by sheepsfoot rollers
' shall be at vertical intervals of not greater than four feet.
In addition, fill slopes at ratios of two horizontal to one,
vertical or flatter, should be trackrolled. Steeper fill
' slopes shall be over -built and cut-back to finish contours
after the slope has been constructed. Slope compaction
operations shall result in all fill material six or more inches
inward from the finished face of the slope having a relative
' compaction of at least 90% of maximum dry density or that
specified in the Special Provisions section of this
specification. The compaction operation of the slopes shall be
' continued until the Soil Engineer is of the opinion that the
slopes will be stable in regards to surficial stability.
' Slope tests will be made by the Soils Engineer during
construction of the slopes to determine if the required
compaction is being achieved. Where failing tests occur or
other field problems arise,'the Contractor will be notified
' that day of such conditions by written communication from the
Soil Engineer or his representative in the form of a daily
field report. '
' If the method of achieving the required slope compaction
selected by the Contractor fails to produce the necessary
results, the Contractor shall rework or rebuild such slopes
until the required degree of compaction is obtained, at no cost
to the Owner or Soils Engineer.
CUT SLOPES
The Engineering Geologist shall inspect cut slopes excavated in
rock or lithified formational material during the grading
operations at intervals determined at his discretion. If any
conditions not anticipated in the preliminary report such as
perched water, seepage, lenticular or confined strata of a
' potentially adverse nature, unfavorably inclined bedding,
joints or fault planes are encountered during grading, these
i
1
SCST 8631034
conditions shall
Soil Engineer
necessary.
March 31, 1986 Appendix, Page 5
be analyzed by the Engineerkng Geologist and
to determine if mitigating measures are
Unless otherwise specified in the geotechnical report, no cut
slopes shall be excavated higher or steeper than that allowed
by the ordinances of the controlling governmental agency.
ENGINEERING OBSERVATION
Field observation by the Soil Engineer or his representative
shall be made during the filling and compacting operations so
that he can express his opinion regarding the -conformance of
the grading with acceptable standards of practice. The
presence of the Soil Engineer or his representative for the
,observation and testing shall not release the Grading
Contractor from his duty to compact all fill material to the
specified degree of compaction.
SEASON LIMITS
Fill shall not be placed during unfavorable weather conditions.
when work is interrupted by heavy rain, filling operations
shall not be resumed until the proper moisture content and
density of the fill materials can be achieved. Damaged site
conditions resulting from weather or acts of God shall be
repaired before acceptance of work.
RECOMMENDED GRADING SPECIFICATIONS - SPECIAL PROVISIONS
The minimum degree of compaction to be obtained in compacting
natural ground, in the compacted fill, and in the compacted
backfill shall be at least 90 percent.
Detrimentally expansive soil is defined as soil which will
swell more than 3 percent against a pressure of 150 pounds per
square foot from a condition of 90 percent of maximum dry
density and air dried moisture content to saturation, or by a
soil having an expansion index greater than 30.
Oversized fill material is defined as rocks or lumps over 6
inches in diameter. At least 40 percent of the fill soils
shall pass through a No. 4 U.S. Standard Sieve.
TRANSITION LOTS: Where transitions between cut and fill occur
within the proposed building pad, the cut portion should be
undercut a minimum of one foot below the base of the proposed
footings and recompacted as structural backfill. In certain
t
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SCST.8631034 March 31, 1986 Appendix, Page 6
' cases that would be addressed in the geotQchnical report,
special footing reinforcement or a combination of special
footing reinforcement and undercutting may be required.
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