04-5938 (SFD) Geotechnical Investigation.3u uo Ie- JaP sladden palm desert 760 772 3895
LOT 1z. V IuA
Sladden En ineerin
g 9
6782 Stanton Ave., Suite A, Buena Park, CA 90629 (714) 523-0952 Fax (714) 523-1369
39-725 Garand Ln., Suite G, Palm Desert, CA 92211 (780) 772-3893 Fax (7E0) 772-3895
April 29; 2003 Project No. 544-2198
03-04-261
C & G Construction
965 North Second Avenue
Upland, California 91786
Project:, Quarry Ranch Project
The Quarry at La Quint"i
La Quinta, California
Ref. Geotechnical Investigation prepared by Sladden Engineered dated Jul- 31, 2002,
Project No. 544-2098, Report No. 02-07-445.
Geotechnical investigation prepared by Sladden. Engineering dated November 4,
1997, Project No. 544-7042.
As requested; this nlenio has been prepared in order to provide formal confirmation of our recent
telephone conversations regarding the allowable foundation bearing pressures for the above
referenced project. Based upon our review it is our opinion'that the allowable -bearing pressures
for continuous footings may be safely increased frorh 1500 psf for 1800 psf ani the allowable
bearing pressures for isolated pad footings may be safely increased from 1800 to 2000 psf. The
allowable increase for increased footing size and depth remain applicable. Allowable increases of
200 psf for each additional 1 foot of doth and 250 psf for each additional 6 inches in depth may
be utilized if: desired. The maximum allowable bearing pressure -should be 2500 psf. The revised
allowable bearing pressures cotTespon.d th recommended bearing pressures .itilized for the
existing portions of the Quarry developincn
If you have any questions regarding this memo or the referenced report; please contact the
undersigned.
Respectfully submitted,
SLADDEN ENQr1N1EERIN(.T
Brett L. Anderson -
Principal Engineer
Letter/pc
Copies: 2/C & G Construction
I
51a sladden palm'desert 760 772 3895
Tara ` Sladden Engineering
5782 Stanton Ave., Suite E, Buena Park, CA 90621 (562) 864-4121 (714) 523-0952 Fax (714) 523-1369
39-725 Garand Ln., Suite G, Palm Desert, CA 92211 (760) 772-3893 Fax (760) 772-3895
-= -
Project No. 544-2098
02-07-445.
LLC
r.a. California 92253
on: Mr. John Shaw
- . - ?:eoosed Short Course Development
rine Quarry at La Quinta
�a Quinta, California
Geotechnical Investigation
is the report of our Geotechnical Investigation conducted at the site of the proposed
and surrounding residential lots to be located just south and east of the existing Quarry
t_;iaa development in the City of La Quinta, California. The investigation was performed in order
:,;ovide recommendations for site preparation and to assist in foundation design for the proposed
ie ':ial structures.
the results of our field investigation and laboratory testing along with conclusions
ndations fir foundation design and site preparation. This report compCctes our original
s=ci;e of services as described in our proposal dated June 14. 2002.
_.•..rec;ate the opportunity to provide service to you on this project. If you ha-.�e any questions
:. report, please contact the undersigned
es: c`iuliy submitted,
5IDDEN ENGINEERING
• . roil
': ncipa} Engineer
6i uarry Ranch, LLC
r
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32 O�;17a sladden palm desert 760 772 3895 p'3
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PROPOSED SHORT COURSE D8VELOPM8NIT
]I -E QUARRY ATLA()UDN7A�
` L&QDD4IA,CALIFORNIA ^
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July 37.2O02
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� TABLE OF CONTENTS
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' 'YTBODUCTlON'
................................. ........................................ ......................................
....... |
� SC0yE OF VVOR\{ ....................................................
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� —CT D23CD{PT[0N/
--------'--------------------------�
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CONDITIONS.........................................................................
' —USIONSAND RECOMMENDATIONS ........................................ .....................
....... 2
Foundation ign---------------^---------'-----`----
3
'<--tlemqnts.................... ............... �—'�--.--------..-------.----.
.......
--. ]
Loeru| Design —_----'.---------..............................................................
....... 3
�o�ohning Walls .............................................................................................................
....... J
. �x..-znsinaSoils ..............................................
4
Ccncrot 8|ubo+un-Grude.................... .............................. ---------_----�
--� 4
So|uh|e Sulfates -----'.------------^-----------'---
4 �
� Shrinkage . ------------------------------'--.4
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` General. Site GruJn�------------------.---------------
--. 4
� �u,� ondGrubbing
� � /»�----------------------------'
--� 4
�. �.—pantkm o[Bui|ding /\ruxu-------------------------.'
5 �
�l Preparation ofSurfaces to Receive Compacted FUL.-------.------
........ 5
4. Placement ofCompacted Fill ----.----.-----'..-----------
....... 5
5. Preparation of Slab and Pavement Areas ...........................................................
5 }
6. Tcohngmnd lnxoochon-----------------------------
....... -
�..................................... ....................................................................................
....... 6
` APPEND\}(A- Sko9'on'andBuring Logs
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Field Fxp|omtion
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%B' Laboratory Testing �
� Laboratory Test Rcou}m
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.ArY-7-NUU(C ' 1997 UBC Seismic Design Criteria
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sladden palm desert
INTRODUCTION
760 772 3E95
Project No. 544-2098
02-07-445
�, o 7 presents the results of our Geotechnical investigation performed in nrder to provide
:.; ns for site preparation and to assist in the design and construction of (I -e residential lots
cunding the proposed short course. The site is located just south of and east of the existing Quarry at
::a Q:r nta development in the City of La Quinta, California. The associated improverr•ents will include
.:• zd roadways, concrete driveways, concrete walkways, various underground utilities, and landscape
SCOPE OF WORK
The purpose of our investigation was to determine certain engineering characteristics of the near surface
0:!s on the site in order to develop recommendations for foundation design and site preparation. Our
::.�es`iation included field exploration; laboratory testing, engineering analysis and 11-e preparation of
i. r .aluation of environmental issues or hazardous wastes was not within the :cope of services
:cep. Our investigation was performed in accordance with contemporary geotechnical engineering
principles and practice. We make no other warranty, either express or implied.
PROJECT DESCRIPTION
rc ect site is located just south and cast of the existing Quarry at La Quinta develoFment in the City
of La Quinta, California. The preliminary plans indicate that the project will consist of a new par 3 golf
course and surrounding residential lots. It is our understanding that the proposed residential buildings
`?e of relatively lightweight wood -frame construction and will be supported by conventional shallow
footings and concrete slabs on grade. The associated site improvements will iiclude, concrete
,.:._v� and driveways, paved roadways, landscape areas and various underground utilities.
.:oject site is presently vacant and the ground surface is covered with scattered desert brush, short
r -ass, weeds and minor debris. The majorivy of the project is relatively level throughou- with an overall
�•, ��-a.rd slope to the north and east. Two large lots are located on the natural hillside just south of the
:12 Quarry at La Quinta Golf Course. The adjacent properties to the south, and east are presently
single family residences.
Based upon our previous experience with lightweight wood -frame structures, we expect that isolated
column loads will be less than 30 kips and wall loading will be less than to 3.0 kips per linear foot.
Grze;'ns is expected to include cuts and fills to match the nearby elevations and to constru ;t level building
. `1;s does not include removal and/or recompaction of the primary foundation bea_ ing soils within
a_eas. If the anticipated foundation loading or site. grading varies substartially from that
c recommendations included in this report should be reevaluated.
SUBSURFACE CONDITIONS
�i'.e is underlain primarily by fine to coarse grained alluvial sands with scattered gra-fel and cobbles.
:.- a:;:V iai sands were fairly uniform in composition except for gravel and cobble conte -it. The alluvial
_encs typically contained less than ten percent fines (clay and silt sized particles). In general, the site
soils appear somewhat loose near the surface but field blow counts indicate that density generally
increases with depth. The site soils were found to be dry throughout the depth of our explDratory borings.
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23 02 08:18a sladden palm desert 760 772 3895 p.5
2002 -2-
Pro ect No. 544-2098
02-07-445
:Zssification testing indicates that the near surface soils consist primarily of fine to coarse
.: ?-ll;;vial sands. Expansion testing indicates that the surface soils are non -expansive and fall within
"very low" expansion category in accordance with the Uniform Building Code classification system.
The somewhat loose and dry conditions suggest that the near surface soils may be susceptible to
?;ehtal settlements due to the anticipated foundation loading and the introduction o[ water.
was not encountered within our borings but is expected to be in excess of 2200 feet below the
existing ground surface in the vicinity of the site. Groundwater should not be a factor in foundation
design or construction.
CONCLUSIONS AND RECOMMENDATIONS
our field and laboratory investigation, it is our opinion that the proposed residential
:rent is feasible from a soil mechanic's standpoint provided that the recommenda-tions included in
this report arc considered in building foundation design and site preparation. Due to the somewhat loose
and potentially compressible condition of some of the near surface soils, remedial 9•ading including
and recompaction is recommended for the proposed building areas. We recommend that
:-,.��.,J X\�ithin the proposed building areas include extensive site watering and recontpaction of
foundation bearing soils in order to provide a uniform mat of compacted soils beneath the
building foundations, Specific recommendations for site preparation are presented in :he Site Grading
section of this report.
was not encountered within our borings and groundwater is expected to be in excess of 200
the existing ground surface in the vicinity of the site. Due to the depth to groundwater;
iquefaction analyses were not performed. Based upon the depth to'groundwater„thc potential for
_!efaction and the related surficial affects of liquefaction impacting the site are considef ed negligible.
"he site is located within an active seismic area of Southern California within approximately 15.0 5
^f t.,e San Andreas fault. Strong ground motion'resulting from earthquake a--tivity along tfic
>aa Andreas or San Jacinto fault systems is likely to impact the site during the anticipated lifetime; (Jutii =1. c
structures. Structures should be designed by professionals familiar with the geologic and seismic
setting of the site. As a minimum, structure design should conform with UniformBuild_ng Code (UBC)
requirements for Seismic Zone 4. Pertinent seismic design parameters as included within the 1997 UBC
"2 s•_,.m-nanzed in Appendix C.
Cia occur within each of our exploratory borings and the surface soils will b-2 susceptible to
caving within deeper excavations. All excavations should be constructed in accordance with the nurmal
CaIOSHA excavation criteria. On the basis of our observations of the materials encountered, we
aa.tic:pate that the subsoils will conform to those described by Cal0SHA as Type C. Soil conditions
e verified in the field by a "Competent person” employed by the Contractor.
?e surface soils encountered during our investigation were found to be non -expansive. Laboratory
testing indicated an Expansion Index of 0 which corresponds with the "very low" category in accordance
with UBC Standard 18-2. if imported soils are to be used during grading, they should have an Expansion
Index of less than 20.
08:18a
,cly 31, 2002
sladden palm desert
-3 -
760 772 3895
Pro_lect No. 544-2098
02-07-445
r2 following recommendations present more detailed design criteria that have been developed on the
of our field and laboratory investigation.
Foundation Design: The results of our investigation indicate that either conventional shallow
ce'iiicuous footings or isolated pad footings; which are supported upon properly recompacted
sods, may be expected to provide satisfactory support for the proposed residential structures.
Recompaction should be performed as described in the Site Grading Section of this report.
Footings should ettend a.tleast:'12 inches beneath lowest adjacent grade. Isolated square or
rectangular footings at,least.2:feet square may be designed using an allowable bearing pressure of
1800 pounds per square foot. Continuous footings at least 12 inches wide may be designe;d using
as allowable bearing pressure of 1500 pounds per square foot. Allowable increases of 200 psf for
each additional 1 foot of width and 250 psf for each additional 6 inches of depth may be utilized
if desired. The maximum allowable bearing pressure should be 2500 psf. The allowable bearing
pressures are for dead and frequently applied live loads and may be increased by 1/3 to resist
,,:;lid. seismic or other transient loading.
,are should be taken to see that bearing soils are not allowed to become saturated from the
ponding of rainwater or excessive irrigation. Drainage from the building areas should be rapid
and complete.
The recommendations made in the preceding paragraphs are based on the assumption that all
footings will be supported upon properly compacted soil. All grading shall be performed under
the testing and inspection of the Soils Engineer or his representative. Prior to the placement of
concrete, we recommend that the footing excavations be inspected in order to verify that they
extend into compacted soil and are free of loose and disturbed materials.
ettiements: Settlements may result from the anticipated foundation loads. These estimated
-,Jmate settlements are calculated to be a maximum of I inch when using the recommended
bearing values. As a practical matter, differential settlements between footings can be assumed as
one-half of the total settlement.
te:-al Design: Resistance to lateral loads can be provided by a combination of friction acting
at the base of the slabs or foundations and passive earth pressure along the sides of the
foundations. A coefficient of friction of 0.45 between soil'and concrete may be used with dead
load forces only. A passive earth pressure of 275 pounds per square foot, per foot of depth, may
be used for the sides of footings which are poured against properly compacted native soils.
earth pressure should be ignored within the upper I foot except where confined (such as
beneath a floor slab). When used in combination, either the passive resistance or the coefficient
of fi-iction should be reduced by one-third.
Retaining Walls: Retaining walls may be required to accomplish the proposed construction.
Cantilever retaining walls niay be designed using "active" pressures. Active pressures may be
estimated using an equivalent fluid weight of 35 pcf for native backfill soils with level free -
draining backfill conditions.
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sladden palm.clesert
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760 772 3695
Pro ect No. 544-2098
02-07-445
For walls that are restrained, "at rest" pressures should be utilized in design. At rest pressures.
=� estimated using an equivalent fluid weight of 55 pef for native backfill soils \vIth level
--,aining backfill conditions.
Expansive Soils: Due to the prominence of non -expansive soils on the site, special expansive
soil design criteria should not be necessary for the design of foundations and concrete slabs -on -
grade. Final foundation and slab design criteria should be established by the Structural Engineer.
Concrete. Slabs -on -Grade: All surfaces to receive concrete slabs -on -grade sh•Duld be underlain
by recompacted soils as described in the Site Grading Section of this report. Where slabs are to
receive moisture sensitive floor coverings or where dampness of the floor slab s not desired, we
recommend:the use of an appropriate vapor barrier. Vapor barriers should be protected by sand
is girder to reduce the possibility of puncture and to aid in obtaining uniform concrete curing.
reinforcement of slabs -on -grade in order to resist expansive soil pressures may not be required
however; reinforcement will have a beneficial effect in containing cracking due to concrete
shrinkage. Temperature and shrinkage related cracking should be anticipate] in all concrete
slabs -on -grade. Slab reinforcement and the spacing of control joints should be cetermined by the
Structural Engineer.
Soluble Sulfates: The soluble sulfate concentrations of the surface soils were determined to be
29 partsper million (ppm). This is within the usual allowable limits for the use of Type 11 cement
and the use of Type V cement or special sulfate resistant concrete mixes should got be necessar'
<�ge and Subsidence: Volumetric shrinkage of the material that is excavated and replaced
alz controlled compacted fill should be anticipated. We estimate that this shrinkage could vary
from 10 to 15 percent. Subsidence of the surfaces that are scarified and com;)acted should be
between 0.1 and 02 tenths of a foot. This will vary depending upon the type of equipment used,
the moisture content of the soil at the time of grading and the actual degre✓ of compaction.
a"ained.
These values for shrinkage and subsidence are exclusive of losses that will occur due to the
stripping of the organic material from the site, the removal of oversized materials.
General Site Grading: All grading should be performed in accordance with the grading;
ordinance of the City of La Quinta, California. The following recommendations have been
c e\-zloped on the basis of our field and laboratory testing:
1. Clearing and Grubbing: Proper clearing of any existing vegetation associated root
systems, and debris will be very important. All surfaces to receive compacted fill should
be cleared of roots; vegetation, debris, and other unsuitable materials that should be,
removed from the site. Soils,.that are disturbed due to the removal of the surface
vegetation and debris should be replaced as controlled compacted fill under the direction
of the Soils Engineer.
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July 31, 2002
-5- Prosect No. 544-2098
02-07-445
Preparation of Building Area. In order to provide firth and uniform bearing conditions,
we recommend watering and recompact ion throughout the building and.foundation areas.
The building areas should be watered so that near optimum moisture cortent is attained to
a depth of at least 3 feet below existing grade or 4 feet below pad grade, whichever is
deeper. The exposed surface should then be compacted with heavy eq_iipment so that a
minimum of 90 percent relative compaction is attained to a depth of at least 2 feet below
existing grade or 3 feet below pad grade, whichever is deeper. Fill material may then be
placed as recommended in Item 4 below. Overexcavation and recompaction of the
surface soils is recommended for transition lots including the 2 lots located within the
natural hillside south of the existing Quarry at La Quinta development.
3. Preparation of Surfaces to Receive Compacted Fill: Other areas to receive compacted
fill should be brought to near optimum moisture content and compacted to a minimum of
90 percent relative compaction.
4. Placement of Compacted .Fill: Fill materials consisting of on-site soils or approved
imported granular soils, should be spread in thin lifts, and compacted at near optimum
moisture content to a minimum of 90 percent relative compaction. Imported material
shall have an. Expansion Index not exceeding 20. The contractor shat notify the Soils
Engineer at least 48 hours in advance of importing soils in order to provide sufficient
time for the evaluation of proposed import materials.
The contractor shall be responsible for delivering material to the site tlmt complies with
the project specifications. Approval by the Soils Engineer will be based upon material
delivered to the site and not the preliminary evaluation of import sources:
Our observations of the material encountered during our investigation indicate that
compaction will be most readily obtained by means of heavy rubber-wlleeled equipment
and/or vibratory compactors. At the time of our investigation, the subso-Js were found to
be very dry. A more uniform and near optimum moisture content shoved be maintained
during recompaction and fill placement.
Preparation of Slab and Paving Areas: All surfaces to receive asphaltconcrete paving
or concrete slabs -on -grade, should be underlain by a minimum compacled fill thickness
of 12 inches. This may be accomplished by a combination of scarification and
recompaction of the surface soils and placement of the fill material as controlled
compacted fill, Compaction of the slab and pavement areas should be to a minimum'of
90 percent relative compaction.
Testing and Inspection: During grading tests and observations should )e performed by
the Soils Engineer or his representative in order to verify that the trading is being
performed in -accordance with the project specifications. Field density testing shall be
performed in accordance with acceptable ASTM test methods. The mini_ntnn acceptable
degree of compaction should be 90 percent of the maximum dry density as obtained by
the ASTM D1557-91 test method. Where testing indicates insufficient density,
additional compactive effort shall be applied until retesting indicates satisfactory
compaction. L
02 .08:19a sladden palm,desert 760 772 3895 p.9
-6- Protect No. 544-2098
02-07-445
GENERAL
:. and recommendations presented in this report are based upon an interpolation of the soil
:ons bctween the exploratory boring locations and extrapolation of these conditioins throughout the
proposed building area. Should conditions encountered diu'ing grading appcar dif=erent than those
ndicated in this report, this office should be notified.
-'.s _'>>)ort is considered to be applicable for use by Quarry Ranch, LLC for the specif`x, site and project
~:pec herein. The use of this report by other parties or for other projects is not authorized. The
:-eccmmendations- of this report are contingent upon monitoring of the grading operation by a
representativc of Sladden E,nbineering. All recommendations are considered to be tentative pending our
review of the grading operation and additional testing, if indicated. If others are cmploycd to perform any
Zo l testing, this office.. should be notified prior to such testing in order to coordinate any required site
s - pur representative and to assure indemnification of Sladden Engineering.
i;;i•estigation was conducted prior to the completion of plans for the project. We recommend that a
ire job conference be held on the site prior to the initiation of site grading. The purpose=of this meeting
be to assure a complete understanding of the recommendations presented in this report as they apply
actual grading performed.
- ' Sladd[rn F.[[uini�nrinn
22 02 �08:20a sladderi balm desert`` ' 760 772 3895 P.10
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Approximate Boring Locations Proposed Short Course '
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Project Number: 544-2098-- 1 Date: 7-29-02
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