BRES2014-1061 Geotechnical Report5'AH ? 0 6 �,-v,.
RECEIVED
JUL 18 2014
CITY OF LA QUINTA j
COMMUNITY DEVELOPMENT
.GEOTECHNICAL. ENGINEERING REPORT
DESERT LAKE � v r
•
PALM DESERT, CALIFORNIA
BUILDING OF. LA QUINTA
& SAF E-Iy DEPT.
APPR VED
FOR CON RUCTION
DATE
PREPARED FO
STUART ENTERPRISES, LTD_
THIS DOCUMENT WAS ISSUED PREVIOUSLY AND MAY
NOT REFLECT CURRENT SITE COMIDATIONIS ANJIOR
STANDARDS OF GEOTECHNICAL PRA=;TICE. 'THE
CONTEl,ITS OF THE DOCti;: E'.iT S<�C)I;s iJ -JOT BE USED
OR. HELIED'.UPON' WITHOUT A REVIEW BY QUALIFIED
PROFESSIONALS.
(Init.) (Date)
EARTH SYSTEMS CONSULTANTS
B7 -1405—P1
NOVEMBER 2, 1989
j
ena Engineers, Inca
AN EARTH SYSTEMS, INC. COMPANY
79-811 B COUNTRY CLUB DRIVE • BERMUDA DUNES, CALIFORNIA 92201 • PHONE (619) 345-1588 • FAX (619) 345-7315
November 2, 1989
Stuart Enterprises, Ltd.
9525 Wilshire Boulevard - Suite 611
Beverly Hills, California 90212
Attention: Woody Stewart
Project: Desert Lake
La Quinta, California
Subject: Geotechnical Engineering Report
87-14.05-P 1
89-10-631
Presented herewith is our Geotechnical Engineering Report prepared for the
proposed residential development to be located in La Quinta, California.
This report incorporates the tentative information supplied to our office
and in. accordance with the request, recommendations for general site
development and foundation design are provided.
This report was prepared to stand as a whole, and no part of the report
should be excerpted or used to exclusion of any other part.
This report completes our scope of services in accordance with our
agreement. Other services which may be required, such as plan review and
grading observation are additional services and will be billed according to
the Fee Schedule in effect at the time services are provided.
Please contact the undersigned if there are any questions concerning this
report or the recommendations included herein.
Respectfully submitted,
BUENA ENGINEERS, INC- Reviewed an
t
R. Layne Richins
Staff Geologist
�? K R.
G�
m
o. C 041210
331-81
Joseph R.
�L Civil.Engine o, - CAU
��P
Brett L. Anderson
Project. Engineer
RLR/BLA/JRV/rcl
HD/SER/Copies: 6 -Stuart Enterprises, Ltd.
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TABLE OF CONTENTS
INTRODUCTION--------------------------------------. :..._... - -- - - -
1
PURPOSE AND SCOPE OF WORK ---------------------------------------------------------------
1
SITE DESCRIPTION ------------ ----------------------------------- ---- ---- --------
2
FIELD EXPLORATION ---------------------------------------- -- - -- ----- - --= - - - --= -- --
2
.LABORATORY TESTING----------------- -----------•------------------- -
SOILCONDITIONS----------------------------------------------------------------------------------
4
GROUNDWATER--------------------------------------------------------------------------------------------
4
REGIONALGEOLOGY -------------------------------------------------------------------------------
5
LOCAL GEOLOGY------------------------------- ..------- = --- = - - -- - - - -- -
5
DescriptiveGeology --------------------------------------------------------------------------
5
Structural Geology ........:.....
GEOLOGIC HAZARDS ............................. ----------- -------- ------ -------------
6
Primary-------------------------------------------------------------------------------------------
6
Secondary---------------------------------------------------------------------------------------_-
8
Non -Seismic --------------------------------- - - - ----- --- - ----- - ------._..._
8
CONCLUSIONS AND DISCUSSIONS ---------------------
9
SITE DEVELOPMENT AND GRADING------------------------------------------------------
10
Site Development - Grading---------------- ----------- •--------------------------------
11
Site Development - Slope Stability -------------------------------------------------
13
Site Development - General-------------------------------------------------------------- .
13
Excavations---------------------------------------------------------------------------------- -.....
15
Traf f i c Areas ---- ----------------------------------------- •------ ------ ------------------------•--
15
UtilityTrenches --------------------------------------------------------------------------------
17
STRUCTURES-----------------------------=-------------------------------------------------------------
17
Foundations--------------------------------------------------------------------------------------
17
Slabs -on -Grade------------- ---- - -- = -- -- - -------------- ---- - - --- --- -----
18
Settlement Considerations----------------------------------------------------------------
19
Frictional and Lateral Coefficients --------------------------•----------------------_-
19
Expansion-----------------•------------------------------------------------------------------------
20
AdditionalServices---------------------------------------------------------------------------
20
LIMITATIONS AND UNIFORMITY OF CONDITIONS -------------------------- :------
21
REFERENCES------------------------------------------------------------=-------------------------------
23
APPENDIX A
Site and Vicinity Map
Logs of Borings
APPENDIX B
Summary of Test Resul is
Table 29-A
APPENDIX C
Standard Grading Specifications
}
November 2, 19.89
INTRODUCTION
877-1405-Pl�
89-10-831
This Geotechnical Engineering Report has been prepared for the proposed
residential development to be located in La Quinta, California.
A. it is assumed the proposed residential structures will be of
lightweight one (1) or two (2) story construction. It is also assumed
that the buildings will be supported by normal continuous or pad
footings.
B.. Structural considerations for residential column loads of .up to 20
kips and a maximum wall loading of 2.O kips per linear foot were used
as a basis for recommendations related to the construction of the
residential buildings.
C. These are estimated values since foundation plans were not available
at the time of .production of this report. If design loading is to exceed
these assumed values, it will be necessary to reevaluate the given
recommendations.
D. All loading is assumed to be dead plus reasonable live load.
PURPOSE AND SCOPE OF WORK
The purpose of our services was to. evaluate the site soil conditions, and to
provide conclusions and recommendations relative to the site and the
proposed development. The scope of work includes the following:
A. A geologic reconnaissance of the site.
B. Shallow subsurface exploration by drilling.
C.- ''Laboratory testing., of - selected soil samples. obtained from the
exploratory borings drilled for this project.
D. Review of selected technical literature pertaining to the site.
E. Evaluation of field and laboratorydata relative to soil conditions.
F. Engineering analysis of the data obtained from the exploration and
testing programs.
G. A summary of our findings and recommendations in written report.
0
November 2, 1.989 -2- B7 -1405=P.1
89=10-831
Contained In This. Report Are:
A. - Discussions on regional and local geologic and soil.conditions.
B. Graphic and/or tabulated. results of laboratory tests and field studies.
C_ Discussions and recommendations relative to allowable foundation
bearing capacity, recommendations for foundation design, estimated
total and differential. settlements, lateral earth pressures, site grading
criteria, geologic and seismic hazards.
Not Contained In This Report:
A. This report does not address the potential presence of hazardous
materials in any manner.
SITE DESCRIPTION
The site of the proposed project is located on the west end of Avenue 58,
south and west of Lake Cahuilla in La Quinta, California.
A. The site of the proposed development is currently vacant with
scattered desert brush, short grass, weeds, cactus and debris.
B. The property has an overall slope to the east.
C. The base of the Santa Rosa Mountains form the south and west edge of
the site.
D. The existing Riverside County aggregate pit occupies the eastern edge
of the site.
FIELD EXPLORATION
Exploratory borings wvere drilled for observing the soil profile and obtaining.
samples for further analysis.
November 2, 1989 -3-
B7-1405-Pi
69-10-831
A. Ten (10) borings were drilled for soil profiling and sampling to a
maximum depth of twenty-six (26) feet below the existing ground
surface. The borings were drilled on May 5, 1989, using an eight (8)
inch diameter hollow -stem .auger powered by a CME 45-B drilling rig.
Alternately, eight (8)'inch diameter continuous flight augers were used.
The approximate boring locations as indicated on the attached plan in
Appendix A, were determined by pacing and sighting from existing
streets and topographic features. The boring locations should be
considered accurate only to the degree implied by the method used.
B. Samples were secured within the borings with a two and one-half (2.5)
inch diameter ring. sampler (ASTM D 3550, shoe_ similar to ASTM D
1586). The samples were obtained by driving the sampler with a one
hundred forty (140.) pound hammer; .dropping thirty (30)..inches. The
number of blows required to drive the sampler one foot was recorded.
Recovered soil samples were sealed in containers and returned to the
laboratory for further classification and testing.
C. Bulk disturbed samples of the soils were obtained from. cuttings
developed during excavation of.the test borings. The bulk samples were
secured for classification purposes and represent a mixture of soils
within the noted depths.
D. The final logs represent our interpretation of the contents of the field
logs, and the results of the laboratory observations and tests of the
field samples. The final logs are included in the appendix A of this
report. The stratification lines represent the approximate boundaries
between soil types although the transitions may be gradual.
LABORATORY TESTING
After a visual and tactile classification in the field, samples were returned
to the laboratory, classifications were checked, and a testing program was
established.
A. Samples were reviewed along with field logs to,determine which would
be further analyzed. Those chosen were considered as representative of
soil which would be exposed and/or used in grading and those deemed
within building influence.
November 2,. 1989 -4= 137-1405-P]
89-10-831
B. In-situ moisture' content and unit dry weights for the. core samples
were developed in accordance with ASTM D2937.
C. The relative strength characteristics of. the subsurface soils were
determined from the results of direct shear tests. Specimens were
placed in .contact with water at least twenty-four (24) hours before
testing, and were then sheared under normal loads ranging from 0.5 to
2.0 KSF.
D. Classification tests consisted of: Expansion Index (UBC Standard No.
29-2), Maximum Density -Optimum. Moisture (ASTM D 1557), and
Hydrometer Analysis (California Test Method 203).
E. Refer to Appendix B for tabular and graphic representation of the test
results.
SOIL CONDITIONS
As determined by the borings, site soils were found to consist primarily of
fine to coarse sands with gravel. The boring logs in Appendix A contain'a
more detailed description of the soils encountered.
A. The soils were found to be fairly firm with relatively high blowcounts
and* the majority of the in-place densities indicating relative
compaction near or above ninety (90) percent of maximum density.
B. The soils were found to be very dry throughout.
C. Cobbles and boulders were encountered throughout the site.
D. Clay and silt contents of the soils exhibit low plasticity. Expansion
tests indicate soils to be in the "very low" to "low" expansion category
in accordance with Table 29-A in Appendix 8 of this report. Refer to
section F of the structures section for specific explanations and
requirements dealing with expansive soil. .
E. Refer to Appendix B for tabular and graphic representation of the test.
GROUNDWATER
Free groundwater was not encountered in any of the borings. The depth to
groundwater in the area is generally in excess of one hundred. (100) feet.
Fluctuations in. groundwater levels may occur due to variations in rainfall,
temperature and other factors.
November 2, 1989 -57 87-1405-P 1
89-10-831
REGIONAL GEOLOGY
The project site is.located in the western Coachella.Valley near the base of
the Santa Rosa Mountains. The. Coachella Valley is part of the tectonically
active Salton Basin. The basin is a closed, internally draining trough that
has. been filled with a complex series of continental clastic materials
during Pleistocene and Holocene time (Van de Camp, 1973).
The San Andreas rift zone dominates the geology of the Coachella. Valley.
The Banning and. Mission Creek faults, which are parts of the San Andreas
system are responsible for earthquakes recently felt in the Coachella
Valley. Other regional faults that have produced events felt in the Coachella
Valley are the San Jacinto, Imperial and Elsinore faults -(see figures 1 & 2).
Based upon the historical . and prehistoric record; the Coachella Valley
segment of the San Andreas fault system is likely to generate a magnitude
seven (7.0) or greater earthquake within the next fifty (50) years. The
potential for a. magnitude seven (7.0) earthquake within the next fifty (50)
years is estimated by Seih (1985) as "High" (507-90%).
The San Jacinto fault is considered the most active fault in Southern
California. it has produced four (4) magnitude six (6.0) earthquakes .in the
past eighty. bight years. Therefore, we have selected the San Andreas and
San Jacinto faults as the design faults for this particular project.
LOCAL GEOLOGY
Site development is proposed in the alluvial fan area and in and around the
foothill area of the property. Li thol ogi c units observed on-site consist of
Mesozoic Granitic rocks, in the hill areas and Quaternary Alluvium
throughout the site.
A. Descriptive Geol oqu:
On-site lithologic units are described as follows:
I. Mesozoic Granitics -gr
Orange brown to gray brown, coarse grained, ranging in
composition from granite to diorite. Some areas exhibit a gneissic
texture that has been intruded by thin (3-61") non-ma.fic dikes.
Outcrops are highly weathered, with the gneissic texture striking
generally ina northerly direction and dip slightly. (less than 15°)
to the northwest.
u�•
u6'
32•
Base map of southern California region with major. faults'
Fault Map of. Southern California
Figure 1
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November 2, 1989 -6- B7 -1405-P i
.89-10-831
2. Ouarternary Alluvium -Qa
Orange brown to gray-bro.wvn, unconsolidated sand, silt and gravels
deposited by .fluvial process. These deposits are, generally,
slightly consolidated to loose, slightly. silty fine to coarse sand
with gravel. and cobbles to twenty-four (24) inches.
B. Structural Geology:
The subject property is located at the
Mountains. This portion of the mountains
intrusions that have undergone subsequent
metamorphism.
base -of the Santa Rosa
is the result of granitic
periods of deformation and
Deformation of the granitic rocks found on-site has imparted a gneissic
texture observed in some local outcrops. As stated previously, the
gneissic texture strikes generally in a northern direction and dips
gently to the northwest. Jointing is randomly oriented, dipping near
vertical.
No active or potentially active faults are.mapped in or around the site.
The San Andreas Fault Zone is the closest active. fault to the project
and is located approximately nine and nine -tenths (9.9) of a mile to the
northeast. Figure 3 shows the project site in relation to local geologic
features.
GEOIOG I C HAZARDS
A. Primary Seismic Hazards:
Primary seismic geologic hazards that may affect any property in the
seismically active southern California region include ground rupture
and strong ground motion.
Fault Rupture:
a. The project site is not located in an_q Alqui.st-Priolo Special
Study Zones. Nor are any active faults mapped through or
adjacent to the project area. At the time of drilling, no
surface expression of faulting was observed.
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MAP. OF PROJECT SITES
RELATION TO LOCAL GEOLOGY
SANTA ANA MAP SHEET
FIGURE 3
BUENA ENGINEERS, INC. I
- - . . - -- - ' _.. - ..- /1-1
Mdvember 2, 1989
-7-
B7-1405-P1
89-i0-831
b. Some features that could be interpreted as faults were
observed in the rock outcrops on-site. However, these fault
features are associated with the metamorphic deformation of
the granitic rocks during Mesozoic Times. in other words, the
features are too old to be considered as active faults and,
thus, do not pose a hazard to development.
c. Fault rupture would. most likely occur along. previously
established traces. However, fault rupture may occur at other
locations not previously mapped.
2. Ground Shaking:
a. Strong ground motion is the seismic hazard most likely to
affect the site during the life of the intended structures.
Using methods developed by Seed and. I dri ss (1982), the
following table was compiled for anticipated accelerations
which may be experienced during an earthquake at the project
site.
TABLE 1
Esti rated
Maximum Maximum Repeatable -Approximate
Design* Acceleration Acceleration Ground Distance to
Fault Earthquake in Rock in Soil** Accelerations Project Site
San Andreas 7.5 .43g .34g .22g 9.9 mi
San Jacinto 6.5 .23g .20g .13g 13.0 mi
Richter Magnitude
Deep Cohesi onl ess -Soils
b. Groundshaking characteristics will vary from low frequency
with high amplitudes -in the alluvial soils to high frequency
low amplitudes in the rock areas of the site. Duration of
shaking could be from fifteen (15) to thirty-five (35)
seconds.
The site is mapped in Riverside County. Ground Shaking Zone
IIIA, and IIIB. Both Ground Shaking Zones are based on
distance from caustive fault's and soil types.
November 2, 1989
C
Secondary Seismic Hazards:
M
B7 -1405-P1
89-10-831
Secondary seismic geologic hazards that may affect the project site
area include subsidence, liquefaction, seismicly-induced slope failure
and ground lurching.
a. Subsidence, whether seismically related or not, is considered a
potential hazard in this area. Historic records report significant
episodes of subsidence in the La Quinta area due to seismic forces
and/or heavy rain fall and flooding.
b. Liquefaction. is the loss of soil strength as q result of ani increase
in pore grater pressure due to cyclic seismic loading. Conditions
for liquefaction include relatively high water table (within 40' of
surface), low relative densities of the saturated soils and
susceptibility of the soil to liquefy based on. grain size. Our
research indicates water is at depths greater than one hundred
(100) feet below the surface. Also, the project is not located in
the Riverside County Liquefaction Study Zone.
c. Due to the competency of the bedrock materials, the potential for
deep seated slope failure is considered low. However, localized
failure may result in areas of unsupported foliations and joints
exposed by grading.
d. The rock slopes around. the project. are littered with loose cobbles
and boulders imbedded in thin surficial soils. Development
adjacent to the rock slopes could be impacted by downslope
movement of said rocks. In. addition, grading may disturb or
expose more cobbles and boulders, thus, increasing the potential
hazard of downslope rock movement.
e. Ground lurching is generally associated with fault rupture.
Because of the sites distance from any known "active' faults, the
possibility of ground lurching affecting the site is considered low.
Non -Seismic Hazards:
Other geologic hazards that could affect the project site include
landslides, flooding and erosion.
a. No evidence of past landsliding was observed at the site nor are
any known landslides mapped in or around the project site. The
subject property is composed of moderately to steeply sloping
rock slopes that lead to coalescing alluvial fans. .
November 2, 1989 -9- 87-1405-P 1
89-10-831
b. Flooding and erosion are always a consideration in.arid regions.
On-site, the erosion rate is affected by the active uplift of
regional faults, relatively soft rock units, sparse vegetation and
seasonal rains.
c. The Coachella Vallley averages four (4) inches of rain per year.
When large amounts of rain occur suddenly, the surface alluvium
becomes saturated and prevents further infiltration of the rains.
The result is surface runoff and sheet flow drainage on slopes
toward gullies and washes. In addition, desert pavement (a
process where a crust is formed on the alluvial surface) adds to
the "sealing" off of the alluvium surface; thus -increasing runoff.
d: Generally, erosion in the desert can be reduced by minimizing soil
disturbances and diverting seasonal runoff from areas of high
potential erosion. On-site erosion may be reduced by diverting
runoff from the hill area and the large drainages to the north of
the project.
CONCLUSIONS AND DISCUSSIONS
Based on a review of a selected technical literature and site investigations,
it is our opinion than the site is suitable for the intended development
provided it is designed around the noted geologic hazards. The following is
a summary of our conclusions and professional opinions based on the data
obtained. Recompaction of soil will be required to limit settlement and
improve bearing capacity.
A. The primary geologic hazard relative to site development is severe
ground shaking from earthquakes originating on nearby faults. The site
is located in Southern California which is an active seismic area. In
our opinion, a major seismic event originating on either the San
Andreas or San Jacinto fault zone would be the most likely cause of
significant earthquake actvity at the site within the estimated design
life of the proposed development.
B. Settlement due to seismic factors or flooding is a potential hazard in
the La Ouinta area. Only areas of alluvial soils will be affected.
C. Downslope movement of rock* materials is a *potential hazard to
development adjacent to native rock slopes and in hill areas subject to
grading.
November 2, 1989 -10- B7 -1405-P 1
89-10-831
D. Areas of alluvial soils may be susceptible to erosion. Preventative
measures to minimize seasonal flooding and erosion should be
incorporated into site grading.
E. Fluvial erosion may affect the site during construction.
F. Other hazards including liquefaction, landslides and tsunamis are
considered negligible.
G. The potential transition nature of many lots along the south and west.
portions of the site is a major consideration in site grading. Because
differential settlement between fill material and*cut soils or bedrock
is inevitable, all footings should be founded entirely on either fill
soils, cut soils or bedrock.
H. It is our opinion that the upper native. soil will not provide uniform
support for the proposed structure without the recommended sitework.
To decrease the potential for consolidation and to provide a more
uniform and firm bearing support for the proposed structures, we
recommend constructing recompacted soil mats beneath all foundations
.and slabs -on -grade.
It is recommended that any permanent structure constructed on the
site be designed to at least minimum requirements for Seismic Zone 4
based on the latest edition of the Uniform Building Code.
J. Adherence to the following grading recommendations is necessary to
mitigate potential settlement problems due to seismic forces, heavy
rainfall, flooding and the weight of the intended structure.
SITE DEVELOPMENT AND GRADING
Prior to any construction operations, areas to be graded should be cleaned of
vegetation and _other deleterious materials. Appendix C, "Standard Grading
Specifications" contains specific suggestions for removal and disposal of
deleterious substances and, as such, forms a part of these Site Development
and Grading Recommendations.
November 2, 1989 - i i - B7 -1405-P 1
89-10-831
A. Site Development - Grading
Site grading should be visually checked by Buena. Engineers, Inc., or
their representative prior to placement of fill. Local variations in soil
conditions may warrant increasing the depth of. recompaction and/or
overexcavation.
Prior to site grading any existing structures, stumps, roots,
foundations, pavements, leachfields, uncompacted fill, trash piles
and any abandoned underground utilities should be removed from
the proposed building and paving areas. The top surface should be
stripped of all organic growth and along with other debris be
removed from the site.
2. Depressions resulting from these removals should have debris and
loose soil removed and be filled with suitable fill soils adequately
compacted. No compacted fill should be placed unless the
underlying soil has been observed by Buena Engineers, Inc.
3. In order to help minimize potential settlement problems
associated with structures supported on a non-uniform thickness
of compacted fill, Buena Engineers, Inc. should be consulted for
site grading recommendations relative to backfilling large and/or
deep depressions resulting from removal under item one above. In
general, all proposed construction should be supported by a
uniform thickness of compacted soil.
4. The grading of transition lots should be. evaluated for individual
lots. The amount and depth of cuts and fills will determine
whether it is more economical to overexcavate the cut portion of
the lot or extend footings through the fill. Regardless footings
should bear entirely compacted fillsoils, compacted cut soil or
bedrock.
5. Testing shop^red soils are fairly firm but dry. Soils of this type
can be susceptible to consolidation when water is added at the in:-
situ
n-situ conditions. Also, to control differential settlement and to
produce a more uniform bearing condition, foundations should bear
entirely on compacted soils or bedrock. Therefore, recompaction of
the bearing soils is recommended. Compaction is to be verified by
testing.
November 2, 1989 -12- 87-1405-P 1
89-10-831
6. Due to the granular nature of the site soils, -it is expected that
compaction may be obtained to a depth of three (3) to four (4) feet
by heavily - watering and compacting from the surface.
7. Building areas to receive more than one (1) foot of fill should be
moistened to above optimum moisture to a depth of three (3) feet
below original grade or the bottom of footings, whichever is
greater. The exposed surface should be compacted so that at least
ninety (90) percent of maximum density is obtained to a depth of
two (2) feet below original grade or the bottom of footings,
whichever is greater. Fill material should then be placed in eight
(8) inch layers in a loose condition at or near optimum moisture
and compacted to a minimum of ninety (90) percent of maximum
density.
6. Building areas to receive less than one (1) foot of fill and building
areas that are in cut areas, should be moistened to at or above
optimum moisture to a depth of three (3) feet below the bottom of
the footings. The exposed surface should be compacted so that a
minimum of ninety (90) percent of maximum density is obtained to
a depth of two (2) feet below the bottom of the footings. The
intent is to have at least two (2) feet of soil compacted
to a minimum of ninety (90) percent of maximum density
compose the building pad beneath the footings and to have
an additional foot of moisture penetration. Compaction
is to be confirmed by testing.
9. These grading requirements apply to building areas and at least
five (5) feet beyond building limits.
10. Auxiliary structures including freestanding or retaining walls
shall have the existing soils beneath the structure processed as
per items seven (7), eight (8) and nine (9) above. The grading
requirements apply to three (3) feet beyond the face of the walls.
If plans for auxiliary structures and walls are provided for our
review, these recommendations may be revised.
Ndvember 2, 1989 -13- "B7 -1405 -PI
.69-10-831
r
C_
11. it is anticipated that during grading a loss of ap'proximately one
tenth (A) of a foot due to stripping, and, a shrinkage factor of
approximately ten (10) to fifteen (15) percent for the upper three
(3)* feet of soil, may be used for. quantity calculations. This 'is
based on compactive effort needed to produce an average degree of
compaction of approximately ninety-three (93) to ninety-four (94)
percent and may vary depending on - contractor 'methods.
Subsidence is estimated between two-tenths -(.2) to three -tenths
(3) of a foot.
Site Development - Slope Stability
1. Cut slopes in the rock. areas should be stable if constructed to a
one and one-half to one (1 1/2:1), horizontal to vertical, maximum
slope angle and cut less than twenty (20) feet in vertical height.
However, to ease maintenance of* the slopes, a more shallow
dipping slope may be desirable. If a steeper or higher slope is
needed, a geologic review of the specific location is necessary
before construction.
2. Fill slopes should be stable if built to a two to one (2:1),
horizontal to vertical, minimum slope angle and . built no higher
than twenty (20) feet. Fill slopes can either be overfilled and
trimmed back or compacted mechanicaly from the surface.
3. Drainage across fill or cut slopes should be limited to prevent
erosion. Rock cut slopes. are susceptible to erosion because of
their weathered condition. Drainage should be diverted from
L to appropriate drainage collection devices that empty into
-the site storm drainage system.
4. Downslope movement of rocks on native slopes adjacent to
development is a potential hazard. The hazard can be mitigated by
removal of the rocks, deflection fences or brow ditches.
Site Development - General
The following general requirements listed in this section are
superceded by the recommendations in the -Grading" section A
above.
November 2, 1989 -14- 87-1405-P 1
89-10-831.
2. Previously removed soils, once cleaned of rocks larger than eight
(8).inches in greatest dimension,.and other deleterious material,
may be placed in thin. layers and mechanically compacted back to .
finish grade.
3. Import soil used to raise site grades should be equal to or better
than on-site .soil in strength,. expansion, and compressibility
characteristics. Import soil may be prequalified by Buena
Engineers, Inc. Comments on the characteristics of import will be
given after the material is on the project, either in-place or in
stockpiles of adequate quantity to complete the project.
4. Fill and backfill should be compacted to the minimum of ninety
(90) percent of maximum dry density obtained by the ASTM U 1557
test method.
5. Areas around the structures should be graded so that drainage is
positive and away from the structures. Gutters and down spouts
should be considered as a way to convey water out of the
foundation area. Water should not be allowed to pond on or near
pavement sections.
6. Added moisture within previously compacted fill could result in a
number of reactions at the surface depending upon the amount of
`moisture increase,. the in-place density of the soil, in-situ
moisture content and soil type. Although the soil could in reality
be expanding,. collapsing, moving laterally due to the phenomenon
"creep", the result is usually movement and will most likely
manifest itself visually in structural slabs and street areas as
cracks, (horizontal, lateral or vertical displacement).
7. The apparent cure to the problem is to not introduce excess
moisture into fill material once in place. To help minimize
increased moisture into the fill material, site drainage and
landscape is critical. Site drainage should be in the form of roof
gutter, concrete brow ditcher, ribbon gutters and gutters, storm
drain and other drainage devices.. Landscaping should be such that
water is not allowed to pond. Additionally, care should be taken so
as not to over water landscaped areas.
November 2, 1989 - i S- B7 -1405-P 1
89-10-831
0
8. Failure to control increase in moisture content to compacted fill"
could result in settlement which could compound the problem by
rupturing water lines or other services and/or utilities, .thus
introducing additional moisture into the underlying soil.
9. The Recommended Grading Specifications included in Appendix C.
are general guidelines only and should not be included .
directly into project. specifications without first incorporating
the site specific recommendations contained in the Site
Development - Grading section of this report. Chapter 70 of the
Uniform Building Code contains specific considerations for.grading
and is considered a part of these General Guidelines.
10. It is recommended that Buena Engineers, Inc., -be retained to
provide soil engineering services during construction of 'the.,
grading, excavation, and foundation phases of the work. This is to
observe compliance with the design concepts, specifications or
recommendations and to allow design changes in the event that
subsurface conditions differ from those anticipated prior to start
of construction.
Excavations
1. All excavations should be made in accordance with applicable
regulations. From our site exploration and knowledge of. general
area, we feel there is a potential for construction .problems
involving caving of relatively deep site excavations (i.e. utilities,
etc.). Where such situations are encountered, -lateral bracing or
appropriate cut slopes should be provided.
2. No surcharge loads should be allowed within a horizontal distance
measured from the top of the excavation slope, equal to the depth
of the excavation.
E. Traffic Areas
1. The surface soil from the referenced, project has been sampled in
the location and tested. for R -Value per California Test Method
301. The testing resulted in an R -Values of 71 and 72. The paving
designs listed below are based on a design P, -Value of 70.
November. 2, 1989 -16- B7 -1405-P i
89-10-831
Traffic Index - 6.0
use 4.0" of asphalt concrete on compacted subgrade or
use 3.0" of asphalt concrete on 4.0" Class II Base
Traffic Index= 6.5 .
use 4.0" of asphalt.concrete on compacted subgrade or
use 3.0" of asphalt concrete on 4.0" Class II Base
Traffic Index - 7.0
use 4.0" of asphalt concrete on compacted subgrade or
Use 3.0" of asphalt concrete on 5.0 Class II Base
Traffic Index - 7.5
use 4.5" of asphalt concrete on compacted subgrade or
use 2.5" of -asphalt concrete on 4.0" Class II Base or
Traffic Index - 8.0
use 4.5" of asphalt concrete on 4.0" Class II Base.or
Traffic Index - 8.5
use 5.0" of asphalt concrete on 4.0" Class II Base or
2. These design sections are based on the paved areas being confined
on two (2) sides. , If the minimum requirements of the City of La
Quinta exceed the design sections listed above, the City
requirements may become the basis for design.
3. If paving directig on subgrade, subgrade should be compacted to
ninety-five (95) percent of maximum density. When paving on
Class II Base placed over subgrade, subgrade should also be
compacted to ninety (90) percent and Class II Base to ninety-five
(95) percent of maximum density. During subgrade preparation,
areas should be visually observed by a representative of Buena.
Engineers, Inc. In addition to the required compaction,. the
subgrade should be firm and unyielding when proof rooted with a
fully. loaded water truck.
November 2, 1989 =17- B7 -1405-P 1
89-10-831
F. Uti 1 i tg Trenches
1. Backfill of utilities within -road right-of-way.should be placed in
strict conformance with the. requirements of the governing agency
(Water District, Road Department, etc.).
2. Utility trench backfill within private property should be placed in
strict provisions of this report relating to minimum compaction
standards. In general., service lines extending inside of property
may be backfilled with native soils compacted to a minimum of
ninety (90) percent of maximum density.
3. Backfill operations should be observed and ,tested by Buena
Engineers, Inc., to monitor compliance with these
recommendations.
STRUCTURES
Based upon the results of this. evaluation, it is our opinion that the
structure foundation can be supported by compacted soils placed as
recommended above. The recomendations that follow are based on "very
low" expansion category soils.
A. Foundations
I't is anticipated that foundations will be placed on firm compacted
soils as.recomrnended elsewhere in this report. The recommendations
that follow are based on "very low" expansion category soils.
Table 29-A gives specific recommendations for width, depth and
reinforcing. Other structural consideration may be more stringent
and would govern in any case. A minimum footing depth of twelve
(12) inches below lowest adjacent. finish grade for one (1) story
structures and eighteen (18) inches for two (2) story structures
should"be maintained.
2. Conventional Foundations:
Estimated bearing values are given below for- foundations on
recompacted soils, assuming fill import (if required) to be equal.
to or better than site soils:
a. Continuous foundations of one (1) foot wide and twelve (12)
inches below grade:
November 2; 1989 -18- B7 -1405 -PI
89-10-831
i. 1800 psf for dead plus reasonable live loads.
fl. 2400 p.sf for -wind and seismic considerations.
b: Isolated pad foundations 2' x 2' and .b.ottomed twelve (12)
inches below grade:
i. 2000 psf for dead plus reasonable live loads.
ii. 2650 psf for wind and seismic considerations.
3. Allowable increases of 200 psf per one (1) foot of additional
footing width and 300 psf for each additional six (6) inches of
footing depth may, be used. The maximum allowable bearing will
be 2500 pcf.
4. Although footing reinforcement may not be required per Table 29-
4; -one (1) number four (,04) rebar at top and bottom of *footings
should be considered in order to span surface imperfections. Other
requirements that are more stringent due to structural loads will
govern.
5. Soils beneath footings and slabs should be premoistened prior to
placing concrete.
6. Lateral loads may be resisted by soil friction on floor slabs and
foundations and by passive resistance of .the soils acting on
foundation stem galls. Lateral capacity is based partially on the
assumption that any required backfill adjacent to foundations and.
grade beams is properly compacted.
7. Foundation excavations should be visually observed by the soil
engineer during excavation and prior to placement of reinforcing
steel or. concrete. Local variations in conditions may warrant
deepening of footings.
8. Allowable bearing values are net (weight of footing and soil
surcharge may be neglected) and are applicable for dead plus
reasonable live loads.
B. Slabs -on -Grade
1. Concrete slabs -on -grade should be supported by compacted
structural fill 'placed in accordance with applicable sections of
this report.
November 2, 1989 =19- 67-1405=P 1
89-10-831 .
C.
2. In areas of moisture sensitive floor coverings, an appropriate
vapor barrier should be installed in order to minimize vapor
transmission from the' subgrade soil to the slab. The membrane
should -be covered with two (2) inches of sand to help protect it
during construction. The sand should be lightly moistened just
prior to placing the concrete.
3. Reinforcement of slab -on -grade is -contingent upon the structural
engineers recommendations and the expansion index of the
supporting soil. Since the mixing of fill soil with native soil could
change the expansion index, additional tests should be conducted
during rough grading to determine the' expansion index of the
subgrade soil. Also, due to the high temperature differential
endemic'- to desert.. areas, large- concrete- slabs on grade are
susceptible to tension.cracks. As a minimum, we recommend that
all interior slabs -on -grade be reinforced with 6" x 6" /'x`10 x *10
welded wire fabric. Additional reinforcement due to the expansion.
index *of the site soil should be provided as recommended in
section F below. Additional reinforcement may also be required by
the structural engineer.
4. It is recommended that the proposed perimeter slabs.(sidewalks,
patios, etc.) be designed relatively independent of foundation
stems (free-floating) to help mitigate cracking due to foundation
settlement and/or expansion.
Settlement Considerations
I. Maximum estimated settlement, based on footings founded on firm
soils as recommended, should -be less than one (1) inch.
Differential settlement between exterior and interior bearing
members should be less than one-half (1/2) inch.
2. The majority. of settlement should occur during construction.
D. Frictional and Lateral Coefficients
1. Resistance to lateral loading may be provided by friction acting on
the base of foundations, a coefficient of friction of .50 may be
used for dead load forces.
2. Passive resistance acting on the sides of foundation sterns '(300
pcf, equivalent fluid vv -eight), may be included for ressistance-to
lateral load.
November 2, 1989 -20- B7 -1.405-P 1
89-10-831
F.
G
3. A one-third-( 1/3) increase in the quoted. passive value may be used
for wind or seismic loads.
4. Passive resistance of soils against grade beams and the frictional
resistance between the floor slabs and the supporting soils may be
combined in determining the total Iateral.resistance, however the
friction factor should be reduced to .33 of dead load forces.
5. For retaining walls backfilled with. compacted native soil, it is
recommended that an equivalent fluid pressure of thirty-five (35)
pcf be used for well drained level backfill conditions.
Exyansion
The design of foundations should be based on the weighted expansion
index (UBC Standard No. 29-2) of the soil. As stated in the soil
properties section, the expansion index of the on-site soil is in the
very low (0-20) classification. However, during site preparation, if the
soil is throughly mixed and additional fill is added, the expansion index
may change. Therefore, the expansion index should be evaluated after
the site preparation has been completed, and the final foundation
design adjusted accordingly.
Additional Services
This report is based on the assumption that an adequate program of
client consultation,. construction monitoring and testing will be
performed- during the final design and construction phases to check
compliance with these recommendations. Maintaining Buene Engineers,
Inc., as the soil engineering firm from beginning to end of the project
will help assure continuity of services. These test would be additional
services provided by our firm. The costs of these services 'are .not
included in our present fee arrangements. The recommended tests and
observations include, but are not necessarily limited to the following:
1. Consultation during the final design stages of the project.
2. Review of the building plans to observe that recommendations of
our report have been properly implemented into the design.
3. Observation and testing during site preparation, grading and
placement of engineered fill.
4. Consultation as required during construction.
November 2; 1909 -21- B7 -1405-P 1
89-10-831
LIMITATIONS AND UNIFORMITY OF CONDITIONS
The analysis and recommendations submitted in this report are based in part
upon the data obtained from the ten (10) borings performed on the site. The
nature and extent of variations between the borings may not
become evident until construction_ If .variations then appear
evident; it .will be necessary to reevaluate .,the recommendations
of this report.
Findings of this report are valid as of this date. However, changes in
conditions of a property can occur with passage of time whether they be due
to natural processes or works of man on 'this or adjacent properties. In
addition, changes in7'applicable or appropriate standards occur whether they
result from legislation or broadening of knowledge. Accordingly, findings of
this report may be invalidated wholly or partially by changes outside our
control. Therefore, this report is subject to review and should not
be relied upon after a period of one (1) year_
In the event that any changes in the nature, design or location of the
building are planned, the conclusions and recommendations contained in this
report shall not be considered valid unless the. changes are reviewed and
conclusions of - this report modified or verified in writing.
This report is issued with the understanding that it is the responsibility
of the owner, or of his representative,. to .insure that the
information and recommendations contained herein are .called to the
attention of the architect and engineers for the project and are
incorporated.into the plans and specifications for the project. It is also
the owners responsibility, or his 'representative, to insure that the
necessary steps are taken to see that the general contractor ' and all
subcontractors carry out such recommendations in the field. It is
further understood that the owner or. his representative is..
responsible for submittal. of this report- to th.e appropriate
governing agencies_
Buena Engineers, Inc., has prepared this report for the exclusive use.of the
client and authorized agents. This report has been prepared in accordance
with general IU.accepted soil and foundation engineering practices. No other
warranties, either expressed or implied, are, made as the professional
advice provided under the terms of 'this agreement, and included in the
report.
November. 2, 19.89 -22- B7 -1405-P 1
89-10-831
It is'recommended that Buena Engineers, Inc., be provided the opportunity
for a general review of final design and specifications in order that
earthwork and foundation recommendations may be properly interpreted and
implemented in the -design and specifications. If Buena Engineers, Inc., is
not accorded the privilege of making this 'recommended review, we can
assume no responsibility for misinterpretation of our recommendations:
END OF TEXT
Appendices
November 2, 1989
-23-
REFERENCES
B7 -1405-P1
89-10-831
1. Envicom, Riverside County, 1976, Seismic Safety Element.
2. Greensf el der, Roger W., 1974, Maximum Credible Rock Accelerations
from Earthquakes in California, CDMG Map Sheet 23.
3. PIoessel, M. R. and Slosson, J. E., "Repeatable High Ground Accelerations
from Earthquakes', 1974 California Geology, Vol. 27., No. 9, Pgs. 195-
199.
4.- Seed; H: B. and idriss, I. M., 1982, Ground Motions and Soil Liquefaction
During Earthquakes.
5. Seih, Kerry, 1985, 'Earthquake Potentials Along The San Andreas Fault`,
Minutes of The National Earthquake Prediction Evaluation Council,
March 29-30, 1985, USGS Open File Report 85-507.
APPENDIX A
Site and Vicinity Map
Logs of Borings
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LOG OF BORING
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Job No. B7 -1405-P1
Report No.
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Total Depth = 16'
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DATE May 5, 1989
LOG OF BORING
for
Desert Lake
BORING NO. 4
Job -.No. B7 -1405-P1
Report No.
LOCATION Per Plan
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C
o
o
Depth (ft)
�n
o
Symbol
Core
Blows/ft .
'
a
- � W
o
0, 0 o
�
c
o
rn
CD
N
d
r
M -C
M CD
`.
p
r.
Z
..
0
O
'
o
Unit
Dry Wt,' .
(pcf)
Moisture
(Percent)
Soil Type
Relative
Compaction
(Percent) .
�+
CO
o
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rn
o CO
o C rc
CO
rr rt
iU
CO S
s
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2
rt
1
Z
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r
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rD o
-v Cr
o
rr O
o
C
DATE May 5., 1989
LOG OF BORING
for
Desert Lake
BORING NO. 8
Job No. B7 -1405-P1
Report No.
LOCATION Per Plan
D
0
P
cn
o
o
m
DESCRIPTION
c L- a
� D .�
�
h L
o v
Q'
o
vi
C
'o
? c
°' L
c�o�
C U
REMARKS AND ANALYSIS
r•
'•:
i�
Al: Brown gravelly fine to
coarse sand
SP
Cobbles throughout 10'-'20'
5'
10
15
20
.Total Depth = 20,
No freewater
No bedrock
DATE May 5, 1989
LOG OF BORING
for
Desert Lake
BORING NO. 7
Job No. B7 -1405-P1
Report No. .
LOCATION Per Plan
.-.
�c
V
D
0
o
>
n
w
-
oz
DESCRIPTION
".
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U
V
O
'
>,
Fn.
°
c
O
.?: m c
L
_ O
O
C� U
REMARKS AND ANALYSIS
'
Al: Brown gravelly fine to
coarse sand
SP
Cobbles
Cobbles
5
10
Total Depth = 15'
No freevater
No bedrock
DATE May 5; 1989
LOG OF BORING
for
Desert Lake
BORING NO. 9
Job No. B7 -1405-P1
Report No.
LOCATION Per Plan
.-.
0.
Q
0
°
N
L
r
h
3
DESCRIPTION
`'
3 -.
Q
�
H
° R.
F
O
N
c
0
> ri c
*' °- v
ri
—v &
CJ E0 CL
Li U .r
REMARKS AND ANALYSIS
r,
Al: Brovn gravelly fine to
coarse sand
SP
Cobbles
Cobbles
Cobbles
i
5
10
15
Total Depth = 15'
No freevater
No bedrock
DATE May 5, 1989
LOG OF BORING
for
Desert Lake
BORING NO, 10
Job No.' . B7-140541
Report No. .
LOCATION Per Plan
W
Q
0
E
V)
o
o
4
DESCRIPTION
3
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L
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•U41
? C:REMARKS
L
Boa
C 0
AND ANALYSIS
or
';•
Al: Brown gravelly fine to
coarse sand
gp
Cobbles throughout 3'- 10'
5
10
15
Total Depth = 15'
No freevater
No.bedrock
APPENDIX B
Summary of Test Results
Table 29-A
November 2, 1.989
BORING & DEPTH
.f
10.0
2 @ 2.0
5.0
15.0
20.0
25.0
B-2 67-1622-Pl
89-10-831.
IN—PLACE DENSITIES
RELATIVE
DRY DENSITY
MOISTURE
COMPACTION
113.9
0.8
94
110.0
.0.6
91 x
115.1
1.6
95%
-'l 01.4
1.5
84%
108.9
2.0
90%
107.8
2.1
89%
118.5
2.1
98
B7 -1405—P1
MOISTURE CONTENT IN PERCENT OF DRY WEIGHT
O
O
LL
U
[a
U
cr
W
a
00
O
z
O
CL
z
f-
z
W
O
0
12
METHOD OF COMPACTION
ASTM D-1557-78, METHOD A or C
SOIL TYPE MAXIMUM DENSITY
Al
Boring 1 @ 0-5' 121.3 pcf
122
120
118
OPTIMUM MOISTURE
12.3%
MAXIMUM. DENSITY - OPTI-MUM MOISTURE CURVES
B7-140541
MOISTURE CONTENT IN PERCENT OF 'DRY WEIGHT
O
O
u -
U_
U
cc
W
a.
co
• O
Z
O
a
z
}
CO
Z
W
O
}
Q
O
8 ,. 10 12
METHOD OF COMPACTION
ASTM D-1557-78, METHOD A or C
SOIL TYPE MAXIMUM DENSITY
,. Al Check 123.3 pcf
Boring 5 @ 0-5'
r
124
122
120
OPTIMUM MOISTURE
10.9%
MAXIMUM DENSITY - OPTIMUM MOISTURE CURVES
• 67-1405-P1
N
4.0
N 3.5
F-
O
0 3.0
Cl 2.5
Y
W 2.0
W
0=
1.5
U
Cr)
Z 1.0
0=
Q
W
= 0.5
0 1 1 1 1 i I 1 1 1
0 0.5 1.0 1.5 2.0 2:5 3.0 3.5 4.0 -
NORMAL LOAD (KIPS / FOOT 2 )
DIRECT SHEAR DATA
Soil type: Al
Boring and depth: 1 @ 0-51
Angle of internal. friction:
Cohesion: 80 psf
Samples remolded to 90% -of maximum density
13 Samples relatively undisturbed
67 -1405-P1
4.0r-
C\1 3.5
0 1 1 1 1 V I I I I I
0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0
NORMAL. LOAD (KIPS / FOOT )
DIRECT SHEAR DATA
Soil type: Al Check
Boring and depth:
5 @ 0-5'
Angle of internal. friction: 43-2°
Cohesion: 100 psf
®
Samples
O
to 90% of maximum density
OLL
3.0
relatively
undisturbed
U)
2.5
Y
C
2.0
U
W
1.5
07
C9
Z
1.0
CC
Q
W
r
0:5
co
0 1 1 1 1 V I I I I I
0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0
NORMAL. LOAD (KIPS / FOOT )
DIRECT SHEAR DATA
Soil type: Al Check
Boring and depth:
5 @ 0-5'
Angle of internal. friction: 43-2°
Cohesion: 100 psf
®
Samples
remolded
to 90% of maximum density
D
Samples
relatively
undisturbed
MINIMUM FOUNDATION REQUIREMENTS
0
"16 -for to noyt n,)vp for fnntnntr•e, (I) Ihrmif, h (1n)
Footings for Slab
& Raised Floor Systems (2) (5) (10)
Concrete Slabs
'
3Y:" Minimum
V)
Thickness
v
All Peri-
Interior foot-
Reinforce-
s
_x
meter
ings for slab
ment for
Premoistening
'eighted
Y
v
L
Footings
and raised
continuous
control for soils
Piers under
xpansion
1
f--
(6).
floors (6)
footings
Reinforce-
Total
under footings,
raised floors
idex
1+4
t—
C
c
(3) (8)
ment (4)
thickness
piers and slabs
o
E
o
o
Depth below natural -
of sand
(5) (6)
Z41
0
0
surface of ground
and finish grade
IN FIES
•20
1
6
12
6
12
12
None
6x6-
Moistening of
Piers allowed
cry Low
2
8
15
7
18
18
Required
10/10
ground prior to
for single
ion -Ex-
3
10
18
8
211
24
WWF
2"
placing concrete
floor loads
insi'v0
recommended
only
1
6
12
6
15
12
120% of optimum
2
8
15
7
18
1.8
moisture content
Piers allowed
.-50.
3
10
18
8
24
24
144 top
6x6-
to a depth of
fpr single
)w
and bottom
10/10
4"
21" below lowest
floor loads
WWF
adjacent grade.
only
Testing Required
1
6
12
6
21
12
144 top
6x6-
130% of optimum
2
8
12
8
21
18
and bottom
6/6 1VWF
moisture content
.-90
3
10
15
8
24
24
or #3
to a depth of 27"
Piers not
edium
24" C.W.
4"
below lowest
allowed
adjacent grade.
ars 24" in ext. footing
and bent 3' into slab (9)
Testing Required
1
6
12
6
27
12
145 top
6x6-
140% of optimum
2
8
12
8
27
18
and bottom
6/6 WWF
moisture content
-130
3
10
15
8
27
24
or #3 •
to a depth of 33"
Piers not
:gh
@ 24" e .
4"
below lowest
allowed
adjacent grade.
ars 4" in ext. footing
and bent 3' into slab (9)
Testing Required
bove 130
try High
Special Design by Licensed Engineer/Architect
"16 -for to noyt n,)vp for fnntnntr•e, (I) Ihrmif, h (1n)
FOOTNOTES TO TABLE 29-A
1. Premoistening is required where specified in Table 29-A in order to achieve
maximum and uniform expansion of sails prior to construction and thus limit
. structural distress caused b.y uneven expansion end shrinkage. Other systems
which do not include prernoistening may be approved -by the Building Official
when. such alternatives ere shown to provide equivalent safeguards against
adverse effects of expensive sails.-
2.
ails:
2. Underfloor access crawl holes shell be pravided with curbs extending not less
then. six (6) inches above adjacent grade to preYent surface water from
entering the foundation area.
3. Rein forcement.for continuous foundations.shall be placed not less then three
(3) inches Bbove the battom of the footings end not less then three (3) inches
below the top of the stem.
4. Reinforcement shall be placed at mid -depth of slab.
S. After. premoistening, the specified moisture content of soils shell be
maintained until concrete is placed. Required moiture content shell be
verified by an approved testing laboratory not more than twenty-four (24)
hours prior to placement of concrete.
6. Crawl spaces under raised floors need not be premoistened except under
interior footings. Interior footings which are not enclosed by a continuous
perimeter foundation system or equivelent concrete or masonry moisture
barrier complying with UBC Section 2907 (b) shall be designed and
constructed as specified for perimeter footings. in Table 29-A.
7. A grade beam not less then twelve (12) inches by twelve (12) inches in cross
section, reinforced as specified for continuous foundations in Table 29-A
.shall be provided at gerage.dooropenings.
S. Foundation stem wells which exceed a height of three (3) times the stem
thickness abo.ve lowest adjacent grade shall be reinforced in accordance with
Sections 2415 and 2614 in the UEC or as required by engineering design,
whichever is more restrictive.
9. Bent reinforcing_bers between exterior footing and slab shell. be omitted when
floor is designed as an independent, "floating' slab.
10. Fireplace footings shall be reinforced with e horizonal grid I-oceted three (3)
inches above the bottom of the footing and consisting of not less then .nurnber
four (*4) bars at twelve (12) inches on center each way. Vertical chimney
reinforcing bars shall be hooked under the grid.
APPENDIX C
Standard Grading Specifications
C-1
STANDARD GRADING SPECIFICATIONS
PROJECT: DESERT LAKE
CLIENT- STUART ENTERPRISES, LTD_
1. These Standard Grading Specifications -have been prepared for the
exclusive use of our client for specific application to referenced
project in accordancQ with .generally accepted soil and foundation
engineering practices. No other, warranty, expressed or implied, is
made.
2. These specifications shall be integrated with the Engineering Report
of: which they are a part. Should conflicting statements be found
between these standard specifications and the itemized
recommendations contained in the main body of the:
engineering report, the latter shall _govern_
3. Buena Engineers, Inc., referred to as the soil engineer, should be
retained to provide continuous soil engineering services during
construction of the grading, excavation and foundation phases of the
work. This . is to observe compliance 'with. the design concepts,
sRecifications or recornmendations and to:allow design changes.in the
event that subsurface conditions differ from that anticipated prior to
start of construction.
4. The presence of our field- representative willbe for the purpose of
providing observation and field testing. Our *work does not include
supervision or direction of the actual work of the contractor, his
employees or agents_ The contractor for this project should be so
advised. The contractor should also be informed that neither
the presence of our field representative nor the observation
and testing by our firm .shall excuse him in any way from
defects discovered in his work. it is understood that our firm will
not be responsible for job or site safety on this project. Job 'and site
.safety will be the sole responsibility of the contractor-.
C-2
5. If the contractor encounters subsurface conditions at the site that (a)
.are materially different from those indicated in the contract plans or
in specifications, or.(b) could not have been reasonably anticipated as
inherent inn -the work of the character provided in the contract, the
contractor shall immediately notify the owner verbally and in writing
within 24 hours. This notification shall be a condition precedent before
any negotiations for changed or differing site conditions` can proceed.
If the owner determines that conditions do materially so differ- and
cause an increase or decrease in the contractor`s cost of, or the time
.required for, performance of any part of the work under this contract,
then negotiations shall commence betty' een owner and contractor to
provide equitable adjustment to owner or contractor resulting
therefrom.
6. Whenever the words "supervision", "inspection", or "control" appear
they shall mean periodic observation of the work and the taking of soil
tests as deemed, necessary by the soil engineer for substantial
compliance with plans, specifications and design concepts.
7. These specifications shall consist of clearing and grubbing, preparation
of land to be filled, filling of the land, spreading; compaction and
control of the. fill, and subsidiary work necessary to complete the
grading of the filled areas to conform with the lines, grades and slopes
as shown on the accepted plans.
S. .The standard test used, to define rnininium densities of compaction
work shall be the ASTM Test Procedure D 1557. Densities shall be
expressed as a relative compaction in terms of the maximum density
obtained in the laboratory by the foregoing standard. procedure.
9. Field density tests will be performed by the soil engineer during
grading operations. At least one (1) test shall be made for each five
hundred (500) cubic yards or fraction thereof placed with o minimum of
tw,o (2) tests per layer in isolated areas. Where sh'eepsfoot.rollers are
used, the soil may be disturbed to a depth of several. inches. Density
tests shall betaken in compacted material below the disturbed surface.
When these tests indicate that the density of any layer of fill
or portion thereof is below the required density, the
particular layer or portion shall be reworked until the
required density has been obtained.
C-3
10. Earth -moving and working operations shall be. controlled to prevent
water from running into excavated areas. Excess water shall be
promptly removed and the site kept dry. Fill material shall not be
placed, spread or rolled during .unfavorable weather conditions. When
the work is interrupted by heavy rain, fill operations shall not be
resumed until field tests by the soil engineer indicate that. the
moisture content and density of the fill are. as previously specified.
11. Compaction shall be by sheepsfoot rollers,- vibrating sheepsfoot rollers,
multiple -wheel pneumatic -tired rollers or other types of acceptable
compacting rollers. Rollers shall be of such design that they will be
able to compact the fill to the specified density. Rolling shall be
accomplished while the fill material is within the specified moisture
content range. .Rolling of each layer shall be continuous' -over its entire
area and the roller shall make sufficient trips to insure . that the
required density has been obtained.
12. Existing structures, foundations, trash, debris, loose fill, trees (not
included in landscaping), roots, tree remains and other rubbish shall be
removed, piled or burned or otherwise disposed of so as to leave the
areas that have been disturbed with a neat and finished appearance free
from debris. No burning shall be permitted i.n the area to be filled.
13. When f.iil material includes rock, large rocks will not be allowed to
nest and voids must be carefully filled with small. stones or earth and
properly. compacted. Rock larger than eight (0)'inches in diameter will
not be permitted in the compacted fill without review as to location by
the soil engineer.
14. Organic matter shall .be removed from the surface- upon which the fill,
foundations or pavement sections are to. be placed. The surface shall
then be plowed or scarified to a.depth of at least eight (o). inches and
until the surface is free from ruts, hummocks or other uneven features
which would tend to prevent uniform compaction by the equipment to be
used. Specific recommendations pertaining to stripping and minimum
depth of recompaction of native soils are presented in the main body of
the soi-1 report.
15. Native soil free from organic material and other deleterious material
may be used as compacted fill; however, during. grading operations the
soil engineer will re-examine the native soils for organic content:
h
C-4
16. Imported . material should be ' tested .and reviewed by buena Engineers,
Inc., before being brought to the site. The materials used shall be free
from organic. matter and other deleterious material.
17. Where fills are made on hillsides or exposed slope areas, greater than
ten (10) percent, horizontal benches shall be cut into firm undisturbed
natural ground to provide a horizontal base so that each layer is placed
and compacted on a horizontal plane. The initial bench at the toe of the
fill shall be at least ten (10) feet in width on firm, undisturbed natural
ground at the elevation of the toe stake placed at the natural angle of
repose or design slope. The width and frequency of succeeding benches
will vary with the soil conditions and the steepness of slope.
"18. The selected . -fill material shall be placed in layers which, ..when
compacted, shall not exceed six (6) inches in thickness. Layers shall be
spread evenly and shall be thoroughly blade -mixed during spreading.
After each layer has been placed, mixed and spread evenly, it shall be
thoroughly compacted to a relative compaction of not less than ninety
(.90) percent. The fill operation shall be continued in . six (6) inch
compacted layers, as specified above, until the fill has been brought to
the finished slopes and graded as shown on the'accepted plans.
19. When the moisture content of the fill material. is not sufficient to
achieve required compaction, water shall be added until the soils attain
a moisture content so that thorough bonding is achieved during the
compacting process. When the moisture content of the fill material is
excessive, the fill material shall be aerated by blading or other
satisfactory methods until the moisture content is reduced to an
acceptable content to achieve proper compaction.
20. Existing septic tanks and other underground storage tanks must be
removed from the site prior to commencement of -building, grading or
fill operations. Underground tanks, including connecting drain fields and
other lines, must be totally removed and the resulting depressions
properly reconstructed and filled. Depressions left from tree removal
shall also be properly filled and compacted.
C-5
21. The methods for removal of subsurface irrigation and utility lines will
depend on the depth and location of the line. One . of the following
methods may be used: 1) Remove the pipe and compact the soil in the
trench according to the applicable portions of these ..grading
recommendations, 2) The pipe shall be crushed in the trench. The trench
shall then be filled and compacted according to. the applicable portions
of these grading specifications, 3) Cap the- ends of the line with
concrete to mitigate entrance of water. The length of the cap shall not
be less than five (5) feet. The concrete mix shall. have a minimum
shrinkage.
22. Abandoned water wells on the site shall be capped according to the
requirements of the appropriate regulatory agency. The strength of the
cap shall be at least equal to .the adjacent soils. The final elevation of
the top of the well casing must be a minimum of thirty-six (36) inches
.below adjacent grade prior to grading or fill operations. Structure
foundations should.not be placed over the capped well.