27728 Geotech Report - the QuarryGEOTECHNICAL ENGINEERING REPORT ADDENDUM
THE QUARRY AT LA QUINTA
LA QUINTA, CALIFORNIA
PREPARED FOR
WINCHESTER INLAND
B7 -1405-P2
FEBRUARY 18, 1993
EARTH SYSTEMS CONSULTANTS
0-* Earth Systems Consultants
1111n-
�■'�► Southern California
February 18, 1993
Winchester Inland
41-865 Boardwalk, Suite 101
Palm Desert, California 92260
Buena Engineers Division
79-811 B Country Club Drive
Bermuda Dunes, CA 92201
(619) 345-1588
(619) 328-9131
FAX (619) 345-7315
B7 -1405-P2
93-02-724
Attention: Craig Bryant
Project: The Quarry at La Quinta
La Quinta, California
Subject: Geotechnical Engineering Report Addendum
Ref: Geotechnical Engineering Report by Buena Engineers, Inc.
dated November 2,1989; Report No. 89-10-831
Presented herewith is our Geotechnical Engineering Report Addendum
prepared for the proposed residential development and golf course to be
located in the City of 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,
EARTH SYSTEMS CONSULTANTS Reviewed and Approved,
Hogan R. Wright
Staff Engineer
pc/SER
Copies:
Re
6 - Winchester In
TABLE OF CONTENTS
INTRODUCTION..........................................................................................................1
PURPOSE AND SCOPE OF WORK........................................................................1
SITE DESCRIPTION.....................................................................................................2
FIELD EXPLORATION..................................................................................................2
LABORATORY TESTING..............................................................................................3
SOILCONDITIONS.....................................................................................................4
GROUNDWATER'............'............ ....
ROUNDWATER:.......................................................................................................4
REGIONALGEOLOGY..............................................................................................4
LOCALGEOLOGY.....................................................................................................4
GEOLOGIC HAZARDS...............................................................................................5
Primary.................................................................................................................5
Secondary.........................................................................................................
6
Non -Seismic .......................................................................................................
6
CONCLUSIONS AND RECOMMENDATIONS.....................................................7
SITE DEVELOPMENT AND GRADING.....................................................................8
Site Development - Grading.......................................................................8
Site Development - General.......................................................................9
Excavations......................................................................................................10
TrafficAreas.......................................................................................................11
UtilityTrenches..................................................................................................
l l
STRUCTURES..............................................................................................................12
Foundations.....................................................................................................12
Slabson Grade..............................................................................................13
Settlement Considerations..........................................................................14
Frictional and Lateral Coefficients............................................................14
RetainingWalls................................................................................................15
SlopeStability..................................................................................................15
Expansion.........................................................................................................15
Additional Services........................................................................................16
LIMITATIONS AND UNIFORMITY OF CONDITIONS...........................................16
REFERENCES.............................................................. ...............................................
18
APPENDIX A
Site and Vicinity Map
Logs of Borings
APPENDIX B
Summary of Test Results
Table 2
APPENDIX C
Standard Grading Specifications
EARTH SYSTEMS CONSULTANTS
February 18, 1993 -1- B7 -1405-P2
93-02-724
This Geotechnical Engineering Report Addendum has been prepared
for the proposed residential development and golf course to be
located in the City of La Quinta, California.
A It is assumed that the structures will be of lightweight one or two story
wood frame construction and will be supported by normal
continuous or pad footings.
B. Structural considerations for building column loads of up to 30 kips
and a maximum wall loading of 2.0 kips per linear foot were used as
a basis for recommendations related to the construction of the
proposed residential structures.
C. These values are assumed since specific loading information is not
available at this time. If design loading is to exceed these assumed
values, it may be necessary to reevaluate the given
recommendations.
D. All loading is assumed to be dead plus reasonable live load.
E. It is likely that a clubhouse and maintenance facilities will also be
constructed. Recommendations can be provided once specific
design criteria and locations are known.
PURPOU AND PE 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 general 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 and the
referenced Geotechnical Engineering Report.
E. Evaluation of field and laboratory data 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.
EARTH SYSTEMS CONSULTANTS
February 18, 1993 -2- B7 -1405-P2
93-02-724
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 Our scope of services did not include any environmental
assessment or investigation to determine the presence of
hazardous or toxic materials in the soil, surface water, groundwater
or air, on, below or around this site.
The site is located south and west of Lake Cahuilla on the west end of
Avenue 58 in the City of La Quinta, California.
A The project now includes property directly east and to the northwest
of the original site which is addressed in the referenced report.
B. The property to the east is the site of the previous Riverside County
aggregate pit. The pit area has been excavated to depths in
excess of fifty feet and there are stock piled material, asphalt and
paved areas in some locations on the site.
C. The property to the northwest appears to be in a basically native
state. The property is situated on an alluvial fan complex originating
from the adjacent Santa Rosa Mountains which also occupy
portions of the site.
D. The surface of the native areas is covered with scattered brush,
weeds and abundant cobbles and boulders. There are several
natural drainage coarses of varying sizes intersecting the site.
FIELD EXPLORATION
Exploratory borings were drilled for observing the soil profile and
obtaining samples for further analysis.
A Ten (10) additional borings were excavated in the areas east and
northwest of the previously investigated site. For soil profiling and
sampling to a maximum depth of sixteen (16) feet below the
existing ground surface. The borings were excavated on February 1
EARTH SYSTEMS CONSULTANTS
February 18, 1993 -3- 137-1405-P2
93-02-724
and 2, 1993, using an eight (8) inch diameter hollow -stem augers
powered by a CME 45B drilling rig. The approximate boring
locations as indicated on the attached plan in Appendix A, were
determined by pacing and sighting from existing streets. 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 inside 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.
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.
B. In situ moisture content and unit dry weights for the core samples
were developed in accordance with ASTM D 2937.
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 kips per square foot in general accordance with ASTM D 3080.
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).
EARTH SYSTEMS CONSULTANTS
February 18, 1993 -4- B7 -1405-P2
93-02-724
E. Refer to Appendix B for tabular and graphic representation of the
test results.
As determined by the borings, site soils were found to consist primarily of
very fine to fine windblown sands. 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 the majority of the ring
samples indicating relative compaction near or above ninety (90)
percent of maximum density.
B. The soils were found to be very dry throughout.
C. Clay and silt contents of the soils exhibit low plasticity. Expansion tests
indicate soils to be in the "very low" expansion category in
accordance with Table 2 in Appendix B of this report. Refer to
section G of the structures section for specific explanations and
requirements dealing with expansive soil.
D. Soils should be readily cut by normal grading equipment.
E. As expected the site soil conditions were found to be very similar to
those encountered in our previous borings.
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. Groundwater should not be a
factor in design or construction.
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 which 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).
EARTH SYSTEMS CONSULTANTS
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DATE: Z — / 8 - 93 1 FILE NO.:B7- AD,5 9l
February 18, 1993 -5- 137-1405-P2
93-02-724
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" (50%-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-eight 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 in and around the
foothill area of the property. Lithologic units observed on-site consist of
Mesozoic Granitic rocks, in the hill areas and Quaternary Alluvium
throughout the site.
A Descriptive Geology:
On-site lithologic units are described as follows:
1. Mesozoic Granitics -ar
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 (3-6") non-mafic
dikes. Outcrops are highly weathered, with the gneissic texture
striking generally in a northerly direction and dip slightly (less
than 150) to the northwest.
2. Quarternary Alluvium -Qa
Orange brown to gray -brown, 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 twelve (12) inches.
B. Structural Geoloav:
The subject property is located at the base of the Santa Rosa
Mountains. This portion of -the mountains is the result of granitic
intrusions that have undergone subsequent periods of deformation
and metamorphism.
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.
EARTH SYSTEMS CONSULTANTS
February 18, 1993 -6- B7 -1405-P2
93-02-724
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.
� 0 • e]LOA0I%ula aq
A Prim ry 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.
1. Fault Rupture:
a. The project site is not located in any Alquist-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.
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 any intended structures.
Using methods developed by Seed Idriss (1982) and
modified by Krinitsky, the following table was compiled for
anticipated accelerations which may be experienced
during an earthquake at the project site.
TABLE 1
* Richter Magnitude, Maximum Probable
** Ploessel & Slosson (1974)
EARTH SYSTEMS CONSULTANTS
Estimated
Estimated
Approximate
Design`
Maximum
Repeatable
Distance to
Fault Earthquake
ArrQe1erQiiQn
Acceler to ions"
Prefect Site
San Andreas 7.5
.43g
.28g
9.9 mi.
San Jacinto 6.5
.23g
.159
13.0 mi.
* Richter Magnitude, Maximum Probable
** Ploessel & Slosson (1974)
EARTH SYSTEMS CONSULTANTS
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February 18, 1993 -7- B7 -1405-P2
93-02-724
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 1116. Both Ground Shaking Zones are based
on distance from caustive faults and soil types.
B. Secondory_Seismic Hazards:
Secondary seismic geologic hazards that may affect the project
site area include settlement, liquefaction, seismicity -induced slope
failure and ground lurching.
a. Settlement, whether seismically related or not, is considered a
potential hazard in this area. Historic records report significant
episodes of subsidence in the nearby La Quinta area due to
seismic forces and/or heavy rain fall and flooding.
b. Liquefaction is the loss of soil strength as a result of an increase in
pore water 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. The quarry area of the project has been excavated revealing
40; to 50' cut slopes. The stability of these slopes may be
effected by seismic events on nearby faults.
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.
EARTH SYSTEMS CONSULTANTS
February 18, 1993 -8- B7 -1405-P2
93-02-724
C. N!2n-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.
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 Valley 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 RECOMMENDATIONS
The following is a summary of our conclusions and professional opinions
based on the data obtained from a review of the referenced report
and the additional site investigation.
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 the. San Andreas
fault zone would be the most likely cause of significant earthquake
activity 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 Coachella Valley area. Adherence to the following grading
recommendations should limit potential settlement problems due to
seismic forces, heavy rainfall, flooding and the weight of the
intended structures.
EARTH SYSTEMS CONSULTANTS
February 18, 1993 -9- B7 -1405-P2
93-02-724
C. Areas of alluvial soils may be susceptible to erosion. Preventative
measures to minimize seasonal flooding and erosion should be
incorporated into site grading plans.
D. Onsite cut slopes may be effected by seismic events. More
detailed analysis of present cut slope conditions as they impact the
site will be necessary once more details of the planned
development are known.
E. Other hazards including ground rupture, liquefaction, lurching,
landslides, tsunamis, subsidence and seiches are considered
negligible.
F. The project site is in seismic Zone 4 as defined in Section 2312 (d) 2. of
the Uniform Building Code. It is recommended that any permanent
structure constructed on the site be designed by a qualified
professional who is aware of the project's seismic setting.
G. 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.
H. It is recommended that Earth Systems Consultants be retained to
provide Geotechnical Engineering services during project design,
site development, excavation, grading, and foundation
construction phases of the work. This is to observe compliance with
the design concepts, specifications and recommendations, and to
allow design changes in the event that subsurface conditions differ
from those anticipated prior to the start of construction.
Plans and specifications should be provided to Earth Systems
Consultants prior to grading. Plans should include the grading plans,
foundation plans, and foundation details. Preferably, structural loads
should be shown on the foundation plans.
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.
EARTH SYSTEMS CONSULTANTS
February 18, 1993 -10- B7 -1405-P2
93-02-724
A. Site Develo,.pment - Grading
Site grading and the bottom of all excavations should be observed
by a representative of Earth Systems Consultants 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 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 non -complying fill which,
along with other debris, should 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
compacted as recommended herein. No compacted fill
should be placed unless the underlying soil has been
observed by Earth Systems Consultants
3. In order to help minimize potential settlement problems
associated with structures supported on a non-uniform thickness
of compacted fill, Earth Systems Consultants 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. Due to the granular nature of the site soils, it is expected that
compaction may be obtained to a depth of three (3) or four
(4) feet by heavily watering and compacting from the surface.
If the recommended depth of compaction cannot be
obtained as suggested, some overexcavation may be
necessary.
5. In general, building areas should be heavily watered so that
near optimum moisture is obtained to a depth of three (3) feet
below original grade or three (3) feet below the bottom of the
footings whichever is deeper. The exposed surface should be
compacted with heavy equipment so that a minimum of ninety
(90) percent of maximum density is obtained to a depth of two
(2) feet below original grade or two (2) feet below bottom of
the footings. Fill material should then be placed in thin layers at
near optimum moisture and compacted to a minimum of
ninety (90) percent of maximum density. 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. Compaction is to be confirmed by
testing.
EARTH SYSTEMS CONSULTANTS
February 18, 1993 -11- B7 -1405-P2
93-02-724
6. These grading recommendations apply to building areas and
to areas at least five (5) feet beyond building limits.
7. Auxiliary structures including freestanding or retaining walls should
have the existing soils beneath the structure processed as per
items five and six above. The grading recommendations
apply to three (3) feet beyond the footings. If plans for auxiliary
structures and walls are provided for our review, these
recommendations may be revised.
8. It is anticipated that during grading a loss of approximately one
tenth (.1) of a foot may occur due to stripping (this loss can be
minimized with selective and careful clearing). A shrinkage
factor of about fifteen (15) percent for the upper three (3) feet
of soil, should 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 will vary depending on contractor methods.
Subsidence is estimated between one-tenth (.1) and two-
tenths (.2) of a foot. The potential losses due to oversize
material cannot be estimated until grading commences, but
could be significant.
B. bite Development - General
The following general recommendations listed in this section
are in addition to those listed in the 'Grading' Section A above.
2. All rocks larger than eight (8) inches in greatest dimension should
be removed from fill or backfill material.
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 will not be prequalified
by Earth Systems Consultants 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.
A 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.
5. 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
EARTH SYSTEMS CONSULTANTS
February 18, 1993 -12- B7 -1405-P2
93-02-724
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).
6. 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.
7. 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 the general guidelines.
C. Excavations
All excavations should be made in accordance with
applicable regulations. From our site exploration and
knowledge of the 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.
D. Traffic Areas
Curbs sidewalks and streets should be provided with one (1)
foot of subgrade compacted to ninety (90) percent of
maximum density.
2. On-site parking should be provided with one (1) foot of
subgrade compacted to ninety (90) percent of maximum
density.
3. The surface soil was previously sampled and tested for R -Value
per California Test Method 301. Testing resulted in R.Values of 71
and 72. The following tentative pavement design sections are
based on a design R -Value of 70.
EARTH SYSTEMS CONSULTANTS
February 18, 1993 -13- 137-1405-P2
93-02-724
Traffic Index = 6.0 (Standard Duty Paving)
use 3.0" of Asphaltic Concrete on 4.0" Class II Base
Traffic Index = 7.5 (Heavy Duty paving areas)
use 4.0" of Asphaltic Concrete on 4.0" Class II Base or
use 3.5" of Asphaltic Concrete on 5.0" Class II Base
4. These design sections are
confined on two sides. If tl
Quinta exceed the design
requirements will become the
E. Utility_ Trenches
based on paved areas being
ie minimum requirements of La
sections listed above, the city
basis for design.
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 conformance with the 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 Earth
Systems Consultants, 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 recommendations that follow are based
on "very low" expansion category soils.
A Foundations
It is anticipated that foundations will be placed on firm compacted
soils as recommended elsewhere in this report. The
recommendations that follow are based on "very low" expansion
category soils.
Table 2 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 grade for
one (1) story structures and eighteen (18) inches for two (2) story
structures should be maintained.
EARTH SYSTEMS CONSULTANTS
February 18, 1993 -14- B7 -1405-P2
93-02-724
2. Conventional Foundations:
Estimated bearing values are given below for foundations on
recompacted soils, assuming import fill (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:
i. 1800 psf for dead plus reasonable live loads.
ii. 2400 psf for wind and seismic considerations.
b. Isolated pad foundations 2' x 2' and bottomed 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 3000 psf. The allowable bearing values indicated have
been determined based upon the anticipated maximum
loads indicated in the "Introduction' section of this report. If the
indicated loading is exceeded then the allowable bearing
values and the grading requirements must be reevaluated by
the soil engineer.
4. Although footing reinforcement may not be required per Table
2; nominal reinforcement should be considered to reduce the
potential problems related to cracking due to temperature
and shrinkage stresses and 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 walls. 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.
EARTH SYSTEMS CONSULTANTS
February 18, 1993 -15- B7 -1405-P2
93-02-724
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.
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. We would
suggest that the floor slabs be underlain by a four (4) inch thick
layer of gravel or by an impermeable membrane as a
capillary break. A suggested gradation for the gravel layer
would be as follows:
Sieve Size Percent Passing
3/4" 90-100
No. 4 0-10
No. 100 0-3
If a membrane is used, a low -slump concrete should be used
to help minimize shrinkage. 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. Additional reinforcement
due to the expansion index of the site soil should be provided
as recommended in section G below. Due to the high
temperature differential endemic to the area, the potential for
temperature and shrinkage related cracking should be
addressed. 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.
EARTH SYSTEMS CONSULTANTS
February 18, 1993 -16- B7 -1405-P2
93-02-724
C. Settlement Considerations
1
E.
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.
Frictional and Lateral Coefficients
Resistance to lateral loading may be provided by friction
acting on the base of foundations, a coefficient of friction of .48
may be used for dead load forces.
2. Passive resistance acting on the sides of foundation stems
equal to 350 pcf of equivalent fluid weight, may be included for
resistance to lateral loading.
3. 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 lateral
resistance, however the friction factor should be reduced to .33
of dead load forces.
4. A one-third (1/3) increase in the quoted passive value may be
used for wind or seismic loads.
Retaining Walls
For cantilever retaining walls backfilled with compacted native
soils, it is recommended that an equivalent fluid pressure of
thirty-five (35) pcf be used for well drained level backfill
conditions. For basement walls or other walls with a restrained
condition, an equivalent fluid of fifty-five (55) pcf should be
used.
2. The lateral earth pressure to be resisted by the retaining walls or
similar structures should be increased to allow for surcharge
loads. The surcharge considered should include the loads from
any structures or temporary loads that would influence the wall
design.
3. A backdrain or an equivalent system of backfill drainage should
be incorporated into the retaining wall design. Our firm can
provide construction details when the specific application is
determined. Backfill immediately behind the retaining structure
should be a free -draining granular material. In this case the
majority of the native soils are considered free draining.
EARTH SYSTEMS CONSULTANTS
February 18, 1993 -17- B7 -1405-P2
93-02-724
4. Compaction on the retained side of the wall within a horizontal
distance equal to one (1) wall height should be performed by
hand -operated or other light weight compaction equipment.
This is intended to reduce potential "locked -in" lateral pressures
caused by compaction with heavy grading equipment.
5. Water should not be allowed to pond near the top of the wall.
To accomplish this the final backfill grade should be such that all
water is diverted away from the retaining wall.
Specific slope stability calculations were not performed due to the
lack of specific site development plans. If slopes exceed ten (10)
feet, engineering calculations should be performed to substantiate
the stability of slopes steeper than 2 to 1. Fill slopes should be
overfilled and trimmed back to competent material.
G. Expansion
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 surface soil is in
the "very low" (0-20) classification. However, during site preparation,
if the soil is thoroughly 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.
H. 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 Earth
Systems Consultants, as the soil engineering firm from beginning to
end of the project will help assure continuity of services. Construction
monitoring and testing 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.
EARTH SYSTEMS CONSULTANTS
February 18, 1993 -18- B7 -1405-P2
93-02-724
The analysis and recommendations submitted in this report are based in
part upon the data obtained from the six (6) additional borings and the
previous borings excavated 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 in 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 eighteen (18) months.
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 the appropriate
governing agencies.
Earth Systems Consultants, has prepared this report for the exclusive use
of the client and authorized agents. This report has been prepared in
accordance with generally 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.
It is recommended that Earth Systems Consultants, 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 Earth Systems Consultants, is not accorded the privilege of making this
recommended review, we can assume no responsibility for
misinterpretation of our recommendations.
EARTH SYSTEMS CONSULTANTS
February 18, 1993 -19- B7 -1405-P2
93-02-724
Our scope of services did not include any environmental assessment or
investigation to determine the presence of hazardous or toxic materials
in the soil, surface water, groundwater or air, on, below or around this site.
Prior to purchase or development of this site, we suggest that an
environmental assessment be conducted which addresses
environmental concerns.
END OF TEXT
Appendices
EARTH SYSTEMS CONSULTANTS
February 18, 1993 -20- 137-1405-P2
93-02-724
r�
1. Envicom, Riverside County, 1976, Seismic Safety Element.
2. Greensfelder, Roger W., 1974, Maximum Credible Rock
Accelerations from Earthquakes in California, CDMG Map Sheet 23.
3. Krinitzsky, E.L., Chang, F.K., Magnitude -Related Earthquake Ground
Motions, Bulletin of the Association of Engineering Geologists Vol. XXV,
No. 4, 1988, Pgs. 399-423.
4. Ploessel, M. R. and Slosson, J. E., "Repeatable High Ground
Accelerations from Earthquakes", 1974 California Geology, Vol. 27,
No. 9, Pgs. 195-199.
5. Seed, H. B. and Idriss, I. M., 1982, Ground Motions and Soil
Liquefaction During Earthquakes.
6. 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.
7. Van de Kamp, P. C., "Holocene Continental Sedimentation in the
Salton Basin, California: A Reconnaissance". Geological Society of
America, Vol 84, March 1973
EARTH SYSTEMS CONSULTANTS
APPENDIX A
Site and Vicinity Map
Logs of Borings
EARTH SYSTEMS CONSULTANTS
The Quarry at La Quinta
Date: 2/1/93 Location: Per Plan BORING NO. 1 File No. 67-1405-P2
2
E
3
DESCRIPTION
o
m
o
m O
REMARKS
°
0"
'
Cc o
o
o U
0
_
17
Al :Grey brown fine to
SP/GP
-
very coarse sand and
gravel
5
39
110.4
3.0
88
10
37
A2:Grey brown very fine
SP
Trace gravel
to coarse sand with
15
gravel
J
50
117j
I
-
Relatively undisturbed
Total Depth = 16'
ring sample
No Free Water
-
®
No Bedrock
20
No recovery
25
30
35
40
45
Note: The stratification
lines represent the
approximate boundaries
between the soil types; the
transitions may be gradual.
5 0
The Quarry at La Quinta
Date: 2/1/93 Location: Per Plan BORING NO. 2 File No. 67-1405-P2
a E 0 DESCRIPTION
�_
z
C:
CD m o
N as
REMARKS
o cn o
o
oC E
U)
C CJ
o O
0
15 A1:Grey brown fine to
SP/GP
111.4
2.1
89
very coarse sand and
- gravel
5 50/11
120.6
3.0
96
Trace cobbles
10 50
15 43
H
1 120.51
1
6
Total Depth = 16'
Relatively undisturbed
ring sample
No Free Water
No Bedrock
2 0 ® No recovery
25
30
35
40
45
50
The Quarry at La Quinta
Date: 2/1/93 Location: Per Plan BORING NO. 3 File No. B7 -1405-P2
^
R
p
E
0
3
DESCRIPTION
o
c
,> 'V
m a
REMARKS
p -
M
0
0
0
•E
.o
E
o
c
a U
0
Al :Grey brown fine to
SP/GP
very coarse sand and
22
gravel
122.5
3.3
98
Cobble @ 4'
5
37
Scattered cobbles
10
Relatively undisturbed
Total Depth = 10'
ring sample
No Free Water
®
No Bedrock
No recovery
15
i
20
25
30
35
40
45
50
The Quarry at La Quinta
Date: 2/2/93 Location: Per Plan BORING NO. 4 File No. B7 -1405-P2
2
E
0
DESCRIPTIONz
N
m 21
REMARKS
0
0
0
m a--
o U
0
fC
-
A 1 :Grey brown fine to
SP/GP
very coarse sand and
gravel
5
-
Cobble @ 6'
Total Depth = 8'
1 0
No Free Water
No Bedrock
15
20
25
30
35
40
45
50
The Quarry at La Quinta
Date: 2/2/93 Location: Per Plan BORING NO. 5 File No. B7 -1405-P2
E
0
3
DESCRIPTION
o
5
m a
REMARKS
U)
o
Z)
o
o U
0
i
Al :Grey brown fine to
SP/GP
_
very coarse sand and
gravel
5
Abundant gravel and cobbles
--
.`.`--
Bedrock
Weathered
10
-
Total Depth = 10'
No Free Water
No Bedrock
15
20
25
30
35
40
45
Note: The stratification
lines represent the
approximate boundaries
_
between the soil types; the
50
transitions may be gradual.
The Quarry at La Quinta
Date: 2/2/93 Location: Per Plan BORING NO. 7 File No. B7 -1405-P2
DESCRIPTION
E v a
o
0
m
o
m o
5 0.
REMARKS
p _. fn
0
cc o'
p
o
o U
0
- Al :Grey brown fine to
SP/GP
very coarse sand and
- gravel
5
Boulder @ 7'
Cobbles
10
Total Depth = 10'
-
No Free Water
No Bedrock
15
i
20
25
30
35
40
45
50
The Quarry at La Quinta
Date: 2/2/93 Location: Per Plan BORING NO. 8 File No. 137-1405-P2
E 0
3
DESCRIPTION
o
m0
o
o
m a
REMARKS
�.
c4
o
-0
s
m 0
-.0
0
9
Al :Grey brown fine to
SP/GP
very coarse sand and
-
gravel
5
23
118.7
3.6
95
10
25
15
29
Relatively undisturbed
Total Depth = 16'
-
ring sample
No Free Water
-
No Bedrock
2 0
® No recovery
25
30
35
40
45
50
The Quarry at La Quinta
Date: 2/2/93 Location: Per Plan BORING NO. 9 File No. 67-1405-P2
E a
DESCRIPTION
o
0
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0
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W�
REMARKS
O cn
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•E
c O
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0
- Al :Grey brown fine to
SP/GP
- very coarse sand and
gravel
5
Cobbles 7 - 9'
10
-
Total Depth = 10'
No Free Water
No Bedrock
15
20
25
30
35
40
45
50
APPENDIX B
Summary of Test Results
Table 2
EARTH SYSTEMS CONSULTANTS
February 18, 1993 B-1
BORING/DEPTH 1 @ 0-5'
USCS SP
SOIL DESIGNATION Al
MAXIMUM
DENSITY (pcf) 125.5
OPTIMUM MOISTURE (%) 10.6
ANGLE OF INT. FRIC. 37°
COHESION (psf) 240
EXPANSION INDEX 0
GRAIN SIZE DISTRIBUTION (%)
GRAVEL
48.5
SAND
49.2
SILT
1.4
CLAY
0.9
SOIL DESCRIPTIONS:
Al: Grey brown slightly silty very fine to fine sands (SP/SM)
EARTH SYSTEMS CONSULTANTS
B7 -1405-P2
93-02-724
February 18, 1993 B-2 B7 -1405-P2
93-02-724
RELATIVE
BORING & DEPTH DRY DENSITY % MOISTURE COMPACTION
1 @ 2.0
110.4
3.0
88%
15.0
117.3
2.2
----
2 @ 2.0
111.4
2.1
89%
5.0
120.6
3.0
96%
15.0
120.5
1.5
96%
3 @ 2.0
122.5
3.3
98%
6 @ 2.0
110.6
3.3
88%
5.0
119.4
3.8
95%
15.0
112.6
1.4
----
8 @ 5.0
118.7
3.6
95%
EARTH SYSTEMS CONSULTANTS
B7-1405-P2
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MOISTURE CONTENT IN PERCENT OF DRY WEIGHT
METHOD OF COMPACTIQ�
ASTM D-1557-78, METHOD A or C
SOIL TYPE MAXIMUM DENSITY OPTIMUM MOISTURE
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1 @a 0 - 5'
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B7-1405-P2
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NORMAL LOAD (KIPS / FOOT )
DIRECT SHEAR DATA
Soil type: Al
Boring and depth: 1 @ 0 - 5'
Angle of internal friction: 37°
Cohesion: 240 p$f
® Samples remolded to 90 % of maximum density
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,FQQTNQTE_S T4 TABLE 2
Premoistening is required where specified in Table 2 in order to
achieve maximum and uniform expansion of soils prior to
construction and thus limit structural distress caused by uneven
expansion and shrinkage. Other systems which do not include
premoistening may be approved by the Building Official when such
alternatives are shown to provide equivalent safeguards against
adverse effects of expansive soils.
2. Underfloor access crawl holes shall be provided with curbs
extending not less than six (6) inches above adjacent grade to
prevent surface water from entering the foundation area.
3. Reinforcement for continuous foundations shall be placed not less
than three (3) inches above the bottom of the footings and not less
than three (3) inches below the top of the stem.
4. Reinforcement shall be placed at mid -depth of slab.
5. After premoistening, the specified moisture content of soils shall be
maintained until concrete is placed. Required moisture content
shall 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
equivalent concrete or masonry moisture barrier complying with
UBC Section 2907 (b) shall be designed and constructed as
specified for perimeter footings in Table 2.
7. A grade beam not less than twelve (12) inches by twelve (12) inches
in cross section, reinforced as specified for continuous foundations in
Table 2 shall be provided at garage door openings.
8. Foundation stem walls which exceed a height of three (3) times the
stem thickness above lowest adjacent grade shall be reinforced in
accordance with Sections 2418 and 2614 in the UBC or as required
by engineering design, whichever is more restrictive.
9. Bent reinforcing bars between exterior footing and slab shall be
omitted when floor is designed as an independent, "floating" slab.
10. Fireplace footings shall be reinforced with a horizontal grid located
three (3) inches above the bottom of the footing and consisting of
not less than number four (#4) bars at twelve (12) inches on center
each way. Vertical chimney reinforcing bars shall be hooked under
the grid.
EARTH SYSTEMS CONSULTANTS
APPENDIX C
Standard Grading Specifications
EARTH SYSTEMS CONSULTANTS
February 18, 1993 C-1 B7 -1405-P2
93-02-724
STANDARD GRADING SPECIFICATIONS
PROJECT: THE QUARRY AT LA QUINTA
CLIENT: WINCHESTER INLAND
These Standard Grading Specifications have been prepared for
the exclusive use of our client for specific application to referenced
project in accordance 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. Earth Systems Consultants, 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,
specifications or recommendations 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 will be 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.
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 in 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
EARTH SYSTEMS CONSULTANTS
February 18, 1993 C-2 B7 -1405-P2
93-02-724
part of the work under this contract, then negotiations shall
commence between 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.
8. The standard test used to define minimum 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 a
minimum of two (2) tests per layer in isolated areas. Where
sheepsfoot rollers are used, the soil may be disturbed to a depth of
several inches. Density tests shall be taken 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.
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.
EARTH SYSTEMS CONSULTANTS
February 18, 1993 C-3 B7 -1405-P2
93-02-724
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 in the
area to be filled.
13. When fill 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 (8) 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 (8)
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 soil 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.
16. Imported material should be tested and reviewed by Earth Systems
Consultants, 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.
EARTH SYSTEMS CONSULTANTS
February 18, 1993 C-4 B7 -1405-P2
93-02-724
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.
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.
EARTH SYSTEMS CONSULTANTS
7 3
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APPROXIMATE BORING LOCATIONS