HomeMy WebLinkAboutTract Map 3929 Lot 254 Preliminary Investigation
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RECEIVED
JAN 15 1998
CITY OF TEMECULA
ENGINEERING DEPARTMENT
PRELIMINARY INVESTIGATION
FEBRUARY 14, 1995
GARY NELSON
30016 PECHANGA DRIVE
TEMECULA, CALIFORNIA 92592
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F-94-8987
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E'ebruary 14, 19.95
Gary Nelson
30016 Pechanga Drive
Temecula, California 92592
SUBJECT: PRELIMINARY INVESTIGATION FOR THE SITE LOCATED ON VIA
MONTEREY, TEMECULA; ASSESSOR'S PARCEL #921-232-006, LOT
254, RIVERSIDE COUNTY, CALIFORNIA.
Dear Mr. Nelson:
In accordance with your request and authorization, we have prepared this
report of the Preliminary Foundation Investigation conducted for the above
subject site.
This report presents our findings, conclusions, and recommendations based
on limited field investigation at the time and location of our site review
and may not represent conditions at other times or locations. By
incorporating the limitations herein, we make no other presentations and/or
warranties, expressed or implied. No specific design plans were available
at the time of this investigation.
ENG., INC.
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18040 GRAND AVE.. LAKE ELSINORE, CA 92530
909/678-4333 Fax: 909/678-6668 1-800-972-7800
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VICINITY MAP
SITE: ON VIA MONTEREY, TEMECULA
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SCOPE OF INVESTIGATION
The scope of this investigation included performing the following:
* ,Review of available literature, reports, and maps pertinent to the
-site.
* 'Subsurface investigation consisted of excavating 1 exploratory boring
.down to 15 feet deep. The boring was logged to determine subsurface
soil deposit structures. Representative samples were obtained of
surficial and subsurface materials for laboratory testing. The
approximate location of the exploratory boring is shown on page three.
* Laboratory analysis of selected representative bulk samples for shear
strength, maximum density, soluble sulfate, and expansive potential.
* :Preparation of this report presenting our findings, conclusions, and
. recommendations.
PROJECT DEVELOPMENT
It is our understanding that the proposed development is a single family
dwelling construction to be placed on conventional spread foundations.
Grading of the lot is anticipated to entail cuts and fills from one to four
feet.
SITE DESCRIPTION
The subject site is located on Via Monterey, in Temecula, California. It
is bound on the north by Via Monterey, and on the south, east, and west by
single family dwellings. The property is approximately 1.08 acres in size,
and is mostly accessible. The property is covered with dry weeds,
vegetation, and some trees along the boundaries. No signs of water wells,
rock outcroppings, or natural water courses were observed on the property.
SUBSURFACE INVESTIGATION LABORATORY TESTING
1. total of 1 exploratory boring was excavated in order to determine the
conditions of the near-surface natural material. The boring was logged,
in-place moisture and density of the exposed materials were recorded, and
representative bulk and relatively undisturbed samples were collected for
laboratory testing.
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Laboratory testing consisted of determining the in-place moisture density,
maximum dry density, expansion potential, soluble sulfate content, and
remolded direct shear. In-place moisture densities are shown in the boring
logs (Enclosure A), and the laboratory test results are summarized in
Enclosure B.
EARTH UNITS
Surficial deposits mantle the entire project site to the depth explored.
These soils are brown in color and consist of silty SAND.
GENERAL SITE GRADING
All :grading shall be performed in accordance with the General Earthwork and
Grading Specifications (Enclosure C), and the specifications of the local
agencies should be implemented into the design of the proposed site. Prior
to grading, deleterious trash and vegetation should be removed and hauled
off-site. All areas prepared and approved to receive fill should be
scarified, moisture conditioned, and compacted to a minimum of 90 percent
relative compaction prior to fill placement.
GROUNDWATER
No groundwater or evidence of
exploratory boring at the time and
conditions may be there that would
final plans and specifications.
seepage was encountered within the
location of exploration. However, other
affect the entire proposed project and
CONSOLIDATION/COLLAPSE POTENTIAL
Considering the on-site low in-place densities, the susceptibility for
consolidation/collapse under the proposed load is anticipated within the
upper three feet throughout the site.
EXPANSION POTENTIAL/SOLUBLE SULFATE
Based on the laboratory test results, the on-site soils are primarily silty
sand and are expected to have a low potential for expansion. The soluble
sulfate tests indicated a soluble sulfate content below 150 ppm in
representative soil samples; therefore, Type II cement can be used for
concrete works.
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F-94-8987
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REMOVALS
Partial or complete removal of compressible surface and subsurface
materials will not be necessary during grading. The overexcavation
materials may be moisture-conditioned and recompacted as structural fill.
GENERAL FOUNDATION CRITERIA
The proposed structure may be supported on conventional spread, or
continuous wall footings, provided that they are at least 12 inches wide,
and 112 inches below the final approved grade with one #4 rebar at the top
and bottom or as designed by the structural engineer.
Footings may be designed for a maximum bearing pressure of 1500 psf. A
friction coefficient for concrete on natural and compacted soils of 0.30
maybe employed. The effects of seismic shaking can be mitigated through
consideration of the parameters presented above and by design in accordance
with the latest Uniform Building Code and the Structural Engineers
Association.
The allowable bearing pressure may be increased by one-third when
considering loadings of short duration such as wind or seismic forces.
This foundation criteria is considered minimum and may be superseded by
more restrictive requirements of the structural engineers, architects, or
governing agency.
SLABS-ON-GRADE
Concrete slabs-on-grade should have a minimum thickness of four inches (4")
nominal. The final pad surface should be rolled to provide a smooth, dense
surface upon which to place the concrete. Where moisture-sensitive
materials are to be placed on slabs, the slab should be underlain by a
moisture barrier (polyethylene plastic vapor barrier). Vapor barriers
should have a minimum thickness of 6 mil and should be protected by a two
inch (2") thick layer of sand above in order to reduce the possibility of
punctures and to aid in obtaining a satisfactory concrete cure. Effort
should be made to minimize large moisture content variations in the
underlying soils.
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UTILITY TRENCH BACKFILL
Utility trenches are anticipated to be excavated using trench equipment in
good working condition. The on-site soils are expected to be suitable as
trench backfill provided organic matter and cobbles over four inches in
diameter are r,emoved. Trench backfill should be densified to at least
ninety two percent (92%) relative compaction (ASTM Test Method D-1557-78).
SLOPE PLANTING AND DRAINAGE
We recommended that all graded slopes within the subject site be planted
with groundcover as soon as possible to protect against erosion.
Inadvertent oversteepening of cut slopes should be avoided during fine
grading and landscaping.
All surface runoff should be collected and directed off-site. Accumulation
of surface runoff should be directed off-site by providing a graded swale
or an appropriate surface collector and conduit or other suitable outlet.
Site:runoff should not be permitted to run over the slope.
ADDITIONAL INSPECTION TESTING SERVICES
The Geotechnic.al Consultant should provide continuous inspections and
testing during grading of the subject site. The recommendations provided
in this report are based on preliminary design information and subsurface
conditions disclosed by the limited borings. The outlined subsurface
conditions should be verified in the field during construction. The
consultant should prepare a final as-grade report and maps summarizing all
conditions encountered and any field modification to the recommendations
provided herein. The primary aspects of engineering inspection and testing
should include:
*
:Inspection of all removal and overexcavation.
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Inspection and material testing during fill placement.
*
'After pre saturation of the slab areas, but prior to placement of sand
'and visqueen.
*
During utility trench excavation backfilling and recompaction.
*
:Inspection of footing excavations.
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When any unusual conditions are encountered.
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F-94-8987
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SUMMARY
1.
ALLOWABLE BEARING VALUE: 1500 psf
COEFFICIENT OF FRICTION: 0.30
MINIMUM SHRINKAGE: 5% to 15%
EXPANSION: Low
MAXIMUM DENSITY: 129.0 pcf
OPTIMUM MOISTURE CONTENT: 10.0 %
2.
3.
4.
5.
6.
7.
FOUNDATION DEPTH:
12" X 12"
below lowest adjacent grade for a one
story, light weight single family
dwelling reinforced with one (1) #4 bar
on top and bottom.
8. SLABS-ON-GRADE: 4 inches = Reinforced with 6" X 6"
#10/#10 welded wire mesh. As an
alternate to the above reinforcement,
fiber mesh may be used.
9. PASSIVE PRESSURE: 250 psf
10. INTERNAL FRICTION ANGLE: 27 degrees
11. COHESION: 150 psi
12. ACTIVE PRESSURE: 45 psf
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F-94-8987
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CONSTRUCTION INSPECTION
All grading operations, including site clearing and stripping, should be
inspected by a representative of this firm. The presence of our field
representative will be for the purpose of providing observation and field
testing, and will not include any supervising or directing of the actual
work.of the Contractor, his employees or agents. Neither the presence of
our field representative nor the observations and testing by our firm shall
excuse the Contractor in any way for defects discovered in his work. It is
understood that our firm will not be responsible for job or site safety on
this project, which will be the sole responsibility of the Contractor.
Again, it is imperative that no clearing and/or grading operations be
performed without the presence of a representative of this firm. An on-
site pre-job meeting with the Developer, Contractor, and the Soils Engineer
should occur prior to all grading related operations. It should be
stressed that operations undertaken at the site without the presence of the
Soils Engineer may result in exclusions of certain areas from the final
compaction report for the project. The Contractor and/or operator is fully
responsible for the uniformity of the grading performed in accordance with
the recommendations and the existing grading requirements.
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CONCLUSIONS AND RECOMMENDATIONS
The feasibility of the proposed development depends on the final project
plan and strict adherence to the recommendations.
The conclusions and recommendations in this report are based upon data
obtained from separate sampling locations and interpolation between them,
carried out for the project and the scope of limited services described.
It is assumed and expected that the conditions between locations are
similar to those encountered at the individual locations; however, it is
possible that 'conditions between sampling locations may vary. Should
conditions be encountered in the field that appear different than those
described in this report, we should be contacted immediately in order that
we might evaluate their effect.
If this report or portions thereof are provided to contractors or included
in specifications, it should be understood by all parties that they are
provided for preliminary information only, and should be used as such.
The report and its' contents resulting from this investigation are not
intended or :represented to be suitable for re-use, extensions,
modifications of the project, or for use on any other project. Any
variance from our prescribed requirements and recommendations would nullify
this'report, constituting indemnification of this firm and its' employees
and representatives from any and all liabilities and obligations toward any
party. Furthermore, this report is valid for only one year from the date
of issuance.
Any deviation for any period of time must be approved by this firm in
writing. periodic or minimum yearly inspection of any project with any
deviation from our expressed requirement herein is required to be performed
by 'a soil engineer. Any underground leaks, flooding excavation and
regrading must be reported and/or performed under the supervision of a soil
engineer.
This office will be further available to assist in assuring correct
interpretation of this report's conclusions and recommendations.
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F-94-8987
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LIMITATIONS
Th1sreport is issued with the understanding that it is the responsibility
of ,the owner to ensure that the information and recommendations contained
he~ein are called to the attention of all parties concerned, including but
not limited to the future owners, agents, designers and contractors, and
that necessary steps are taken to ensure that such recommendations are
carried out, under any and all circumstances and conditions.
The interpretation, conclusions and recommendations contained in this
report are based on soil conditions at the time and locations of
observation, and as in most projects, may not necessarily represent any
other areas at any other time. No representation of any kind is made to
the quality, uniformity, chemical characteristic of site material, also
suitability, merchantability and/or cost of the final project plan.
Furthermore, other conditions that may be encountered or changes in the
conditions of the property can occur with the passage of time, whether it
be ,due to natural processes or the works of man on this or adjacent
properties. In addition, changes in applicable or appropriate standards
may occur, whether they result from legislation, the broadening of
knowledge or change of plan. Accordingly, the findings of this report may
be invalidated wholly or partially by any change, for any reason.
Furthermore, this report is subject to review and revision as changed
conditions are identified and a written approval is requested for any use
of :this report beyond one year, to be negotiated by this firm. This firm
may discontinue its service at any time for nonpayment; furthermore, the
use of this report by any party constitutes indemnification of the staff,
representatives and subcontractors of this firm and acceptance of terms and
conditions of the authorization at all times, by all parties. Furthermore,
any and all mitigative measures concerning this report should be performed
under the supervision of this firm.
Our presence at any project is only as a testing firm, we are not involved
in the performance or operation of the proposed development, and we make no
representation to the uniformity of the work performed by the grading
contractor or others. The test locations are randomly selected without any
presumption or expectation for uniformity. Our report or memo does not and
should not be considered as any future liability on this project for any
reason to any person or entity.
The use of this report is subject to a final review and approval of the
project plan and specification by this firm in order to assist in assuring
correct interpretation of this reports' recommendations for use in
applicable sections.
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ENCLOSURE A
BORING LOGS
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ACADEMY BORING LOG SUMMARY
F-94-8987
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PROJECT oil
F-94-8987
DATE: 09/09/94
HOLE oil B-1
PROJECT SITE:
On via Monterev. Temecula
HOLE 'DIAMETER: 6"
DRIVE WT: -----------
INCH DROP: -----------
TOP HOLE ELEV: ------
REF. DATUM:
TECH: RM
RIG: CJ-5
DEPTH
FEET
GRAPH oil BLOW DRY MOISTURE SOIL
COUNT DENSITY %
GEO DESCRIPTION
01
0' - 2.5'
Brown, fine to coarse grain,
silty sand, slightly moist,
loose
02
03
2.5' - 7.5'
Brown, fine to coarse grain,
,silty sand, slightly moist,
moderately dense
04
05
06
07
08
7.5' - 15'
Brown, fine to coarse grain,
silty sand, dry, dense
09
10
11
12
13
14
15
16
17
TOTAL DEPTH: 15 FEET
NO GROUNDWATER ENCOUNTERED
AT THE TIME OF DRILLING OR
24 HOURS LATER.
18
19
NO BEDROCK ENCOUNTERED.
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ENCLOSURE B
LABORATORY TEST RESULTS
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LOCATION
A
SAMPLE
LOCATION
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MAXIMUM DRY DENSITY TEST RESULTS
SOIL DESCRIPTION
MAXIMUM DRY
DENSITY (pcf)
Brown silty sand
129.0
EXPANSION INDEX RESULTS
EXPANSION - INDEX
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B-1
OPTIMUM
MOISTURE (%)
10.0%
EXPANSIVE
CLASSIFICATION
Low
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B-2
LABORATORY TESTING PROCEDURES
MOISTURE AND DENSITY TESTS: Moisture content and dry density
determinations ,were performed on relatively undisturbed samples obtained
from the test borings. The results of these tests are presented in the
boring logs. Where applicable, only moisture content was determined from
"undisturbed" or disturbed samples.
CLASSIFICATION TESTS: Typical materials were subjected to mechanical
grain-size analysis by wet sieving from U.S. Standard brass screens (ASTM
D422). Hydrometer analysis was performed when appreciable quantities of
fines were encountered. The data was evaluated in determining the
classification of the materials. The grain-size distribution curves are
presented in the test data and the Unified Soil Classification is presented
in both the test data and the boring logs.
ATTERBERG LIMITS: The Atterberg Limits were determined in accordance with
ASTM D423 and ASTM D424 for engineering classification of the fine-grained
materials.
DIRECT SHEAR TESTS: Direct shear tests were performed on selected remolded
and/or undisturbed samples which were soaked for a minimum of 24 hours
under a surcharge equal to the applied normal force during testing. After
transfer of the sample to the shear box, and reloading the sample, pore
pressures set up in the sample due to the transfer were allowed to
dissipate for a period of approximately one (1) hour prior to application
of shearing force. The samples were tested under various normal loads, a
different specimen being used for each normal load. The samples were
sheared in a motor-driven, strain-controlled, direct-shear testing
apparatus at a :strain rate of 0.05 inches per minute. After a travel of
0.300 inches of the direct shear machine, the motor was stopped and the
sample was allowed to "relax" for approximately fifteen (15) minutes. The
"relaxed" and "peak" shear values were recorded. It is anticipated that,
in a majority of samples tested, the fifteen (15) minutes relaxing of the
sample is sufficient to allow dissipation of pore pressures set up in the
samples due to application of shearing force. The relaxed values are
therefore judged to be a good estimation of effective strength parameters.
The:results were plotted on the "Direct Shear Summary".
For 'Residual Direct Shear test, the samples were sheared, as described in
the preceding paragraph, with the rate of shearing of 0.001 inches per
minute. The upper portion of the specimen was pulled back to the original
position and the shearing process was repeated until no further decrease in
shear strength was observed with continued shearing (at least three times
resheared) .
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B-3
The~e,are two methods to obtain the shear values: (a) the shearing process
was repeated for each normal load applied and the shear value for each
normal load was recorded. One or more than one specimen can be used in
this method; (b) only one specimen was needed, and a very high normal load
(approximately 9000 psf) was applied from the beginning of the shearing
process. After the equilibrium state was reached (after "relaxed"), the
shear value for that normal load was recorded. The normal loads were then
reduced gradually without shearing the sample (the motor was stopped). The
shear values were recorded for different normal loads after they were
reduced and the sample was "relaxed".
MAXIMUM DENSITY TESTS: The maximum dry density and optimum moisture
content of typical materials were determined in accordance with ASTM D-
1557-78 (five layers). The results of these tests are presented in the
test data.
EXPANSION INDEX TESTS: The expansion potential of selected materials was
evaluated by the Expansion Index Test, U.B.C. Standard No. 29-2. Specimens
are ,molded under a given compactive energy to approximately the optimum
moisture content and approximately fifty percent (50%) saturation or
approximately ninety percent (90%) relative compaction. The prepared one
inch thick by four inch (1" x 4") diameter specimens are loaded to an
equivalent 144 psf surcharge and are inundated with tap water until
volumetric equilibrium is reached. The results of these tests are
presented in the test data.
CONSOLIDATION TESTS: Consolidation tests were performed on selected,
relatively undisturbed samples recovered from the sampler. Samples were
placed in a consolidometer and loads were applied in geometric progression.
The :percent consolidation for each load cycle was recorded as the ratio of
the !amount of vertical compression to the original one inch (I") height.
The 'consolidation pressure curves are presented in the test data. Where
applicable, time-rates of consolidation were also recorded. A plot of
these rates can be used to estimate time of consolidation.
SOLUBLE SULFATES: The soluble sulfate contents of selected samples were
determined by the California Materials Method No. 417.
"R"...,VALUE: The resistance "R"-Value was determined by the California
Materials Method No. 301 for base, subbase, and basement soils. Three
samples were prepared and exudation pressure and "R"-Value determined on
each one. The :graphically determined "R"-Value at exudation pressure of
300 psi is reported.
TRIAXIAL COMPRESSION TESTS: Triaxial compression tests were performed on
selected remolded and/or undisturbed samples according to ASTM 2166
(unconfined) and ASTM 2850 (confined).
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ENCLOSURE C
GENERAL GRADING RECOMMENDATIONS
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F-94-8987
C-1
GENERAL EARTHWORK AND GRADING SPECIFICATIONS
These specifications and the grading details attached represent this firm's
minimum requirements for grading and other associated operations on
construction projects. These specifications and recommendations of the
regulatory agencies should be considered a portion of the project
specifications.
The contractor, prior to a site preparation grading, should arrange a
meeting on the ,site with himself, the developer, the design engineer, the
soils engineer, and representatives of the governing authorities. All
parties should be given at least forty-eight hours notice.
It is the contractor's responsibility to prepare the ground surface to
receive the fills, spread, mix, and compact the fill in accordance with the
job specifications. The contractor should also have suitable and
sufficient equipment in operation to handle the amount of fill being
placed.
PREPARATION OF AREA TO BE FILLED
CLEARING AND GRUBBING
All ,structures marked for removal, timber, logs, trees, brush, and other
rubbish, shall be removed, piled and burned or otherwise disposed of off-
site, so as to leave the areas that have been disturbed with a neat
appearance, free from unsightly debris.
A thorough search shall be made in the vicinity of all existing structures
to be removed for possible underground storage tanks and/or septic tanks
and cesspools. Concrete irrigation lines shall be crushed in place and all
metal underground lines shall be removed from the site.
Allltrees to be removed from the site shall be pulled in such a manner so
as to remove as much of the root system as possible. All cavities created
during clearing and grubbing operations shall be cleared of deleterious
material and backfilled with clean soils and compacted to a minimum of
ninety percent (90%) relative compaction.
PROCESSING
The existing ground which is determined to be satisfactory for support of
fill, shall be scarified to a minimum depth of six inches (6"). Existing
ground which is not satisfactory shall be overexcavated. Scarification
shall continue until the soils are broken down and free of large clay lumps
and until the working surface is reasonably uniform and free of uneven
features which would inhibit uniform compaction.
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F-94-8987
C-2
MOISTURE CONDITIONING
Overexcavated and processed soils shall be watered, dried-back, blended or
mixed as required, to attain a uniform moisture content. For field testing
purposes, "near optimum" moisture should be considered to mean, "optimum
moisture to three percent (3%) above optimum moisture".
Prior to placement of additional compacted fill following a grading delay,
the exposed surface of previously compacted fill should be reprocessed.
This should be accomplished by scarification, watering conditions, then
recompacted to a minimum of ninety percent (90%) of the laboratory maximum
dry density.
No additional fill should be placed following a period of flooding,
rainfall or over watering, until damage assessments have been made and
remedial grading performed.
BENCHING
Where fills are to be placed on ground with slopes steeper than 5:1, then
the ground shall be stepped or benched. The lowest bench shall be a
minimum of fifteen feet (15') wide, two feet (2') deep, shall expose firm
material, and shall be approved by the soils engineer. Other benches shall
be 'excavated into firm material to a minimum width of four feet (4').
Typical benching and keying details have been included in the grading
details.
APPROVAL
All areas to receive fill, including processed areas, removal areas, and
toe-of-fill benches, shall be approved by the soils engineer prior to fill
placement.
All grading operations should be inspected by a representative of this
firm. The presence of our field representative will be for the purpose of
providing observation and field testing, and will not include any
supervision of the actual work by the contractor, his employees, or agents.
It is understood that our firm will not be responsible for job or site
safety on this project, which will be the sole responsibility of the
contractor.
If should be stressed that operations undertaken at the site without the
presence of the soils engineer may result in exclusion of certain areas
from the final compaction report. '
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F-94-8987
C-3
FILL, MATERIAL
GENERAL
Material to be placed as fill shall be free of organic matter and other
deleterious substances, and shall be approved by the soils engineer. Soils
of poor gradation, expansion, or strength characteristics shall be placed
in !areas designated by the soils engineer, or shall be mixed with other
soils to serve as satisfactory fill material.
Import materials shall meet the following minimum requirements:
.A. Plasticity index not to exceed twelve (12).
:B. R-Value not less than twenty-five (25).
C. Not more than thirty percent (30%) passing the #200 sieve.
OVERSIZED MATERIAL
Rocks eight inches (8") and smaller may be utilized within the compacted
fill, provided that they are placed in such a manner that nesting of the
rock is avoided. Fill should be placed and thoroughly compacted to the
minimum requirement over and around all rock.
During the course of grading operations, rocks, or similar
materials greater than twelve inches (12") may be generated.
should not be placed within the compacted fill unless placed as
by the soils engineer.
irreducible
These rocks
recommended
Rocks that are greater than twelve inches (12"), but less than three feet
(3'), that are generated during grading may be placed within an approved
compacted fill area provided that it is done in accordance with the
recommendations in the attached grading details. Rocks greater than three
feet (3') should be broken down or disposed of off site. Rocks up to three
feet (3') should be placed ten feet (10') below the finished grade and
should not be closer than fifteen feet (15') from any slope face. Where
practical, oversized material should not be placed below areas where
structures or deep utilities are proposed.
Oversized material should be placed in windrows on a clean, overexcavated
or unyielding compacted fill area or firm natural ground. Select native or
imported granular soils (SE=30 or better), should be placed or thoroughly
flooded over and around all windrowed rock, such that no voids remain.
Windrows of oversized material should be staggered so that successive
strata of oversized material is ~ot in the same vertical plane.
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COMPACTION
After each layer has been placed, mixed, and spread evenly, it shall be
thoroughly compacted to no less than ninety percent (90%) of the maximum
density in accordance with ASTM D 1557. Compaction shall be by sheepsfoot
rollers, multiple-wheel pneumatic tire rollers or other types of 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 at the specified moisture content. Rolling of each layer shall
be continuous over its entire area, and the roller shall make sufficient
trips to ensure that the desired density has been attained.
Fill slopes shall be compacted by means of sheepsfoot rollers or other
suitable equipment. Compacting operations shall be continued until the
slopes are stable, but not too dense for planting, and that there is no
appreciable amount of loose soils on the slopes. Compacting of the slopes
maylbe done progressively in increments of three to four feet (3'-4') in
fill height or after the fill is brought to its total height.
Field density tests shall be made of each compacted layer of fill. Density
tests may be made at intervals not exceeding two feet (2') of fill height,
provided that at least every 1000 cubic yards of fill are tested. Where
sheepsfoot rollers are used, the soils may be disturbed to a depth of
several inches. Density tests shall be taken in the compacted material
below the disturbed surface. When these tests indicate that the density of
a layer or portion is below the required density, that layer or portion
shall be reworked until the required density has been attained.
The :fill operations shall be continued in six inch (6") compacted layers,
as specified above, until the fill has been brought to the finished slopes
and grades as shown on the approved plans.
SITE PROTECTION
Precautions should be taken to protect the work site from flooding, ponding
or inundation of proper surface drainage. Temporary provisions should be
made during the rainy season to direct surface drainage away from the work
site. Plastic sheeting should be kept on hand to prevent unprotected
slopes from becoming saturated. Where necessary, the contractor should
install check dams, desilting basins, sandbags and other devices to control
erosion.
Following periods of rainfall, the contractor should arrange a walk-over
with the soils engineer to visually assess rain related damage. At the
request of the soils engineer, the contractor shall make all excavations as
necessary to evaluate the extent of rain related damage. Rain related
damage may include erosion, silting, saturation, swelling, structural
distress, or other adverse condition observed by the soils engineer.
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SLOPES
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Compacted fill or backrolled slopes should be limited to a slope ratio of
no steeper than 2:1. All compacted fill slopes shall be overbuilt and cut
back to grade, exposing the firm, compacted fill inner core. The actual
amount of overbuilding shall be increased until the desired compacted slope
surface conditions are achieved. Care should be taken by the contractor to
provide thorough mechanical compaction to the outer edge of the overbuilt
slope surface.
If :excavations for cut slopes expose loose, cohesionless, significantly
fractured or otherwise unsuitable material, overexcavation and replacement
with a compacted stabilization fill should be done. Stabilization fill
construction should conform to the requirements of the attached grading
details. For cut slopes made in the direction of the prevailing drainage,
a non-erodible diversion swale (brow ditch) should be provided at the top-
of-cut.
SLOPE MAINTENANCE
In order to enhance surficial slope stability, slope planting should
consist of de-rooted vegetation requiring little watering. Plants native
to Southern California and plants that are relative to native plants, are
generally desirable. Plants native to other semi-arid and arid areas may
also be appropriate. A qualified Landscape Architect should be contracted
for specific recommendations.
DRAINAGE
Canyon subdrain systems should be installed in accordance with the attached
grading details. Typical subdrains for compacted fill buttresses, slope
stabilization, or sidehill masses, should also be installed in accordance
with the attached grading details.
All roof, pad, and slope drainage should be directed away from slope area
structures to approved disposal areas, via gutters, down spouts, or swales.
Foripad areas created above cut natural slopes, positive drainage should be
established away from the top-of-slopes. This may be accomplished by using
a berm and/or appropriate pad gradient. A recommended overall gradient
away from the top-of-slope should be two percent (2%) or greater. For
drainage immediately away from structures, a minimum five percent (5%)
gradient should be maintained. Pad drainage may be natural or manmade.
See grading details.
TRENCH BACKFILLS
Utility trench backfill can be best placed by mechanical compaction.
Unless otherwise specified, compaction shall be a minimum of ninety percent
(90%) of the laboratory maximum density. As an alternative, where
specifically approved by the soils engineer, granular material (sand
equivalent 30), may be thoroughly jetted in place. Jetting should only be
considered to apply to trenches no greater than two feet (2') in width and
four feet (4') in depth.. Following jetting operations, trench backfill
should be thoroughly compacted by mechanical means.
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ENCLOSURE D
RECOMMENDATIONS FOR SLABS-ON-GRADE
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GENERAL BASIC RECOMMENDATIONS FOR SLABS-ON-GRADE
1. Concrete used for residential concrete slabs must achieve a minimum
compression strength as recommended by (Table 26A-3 1988 UBC) or as
requested by local regulatory agencies.
2. .The concrete should have a minimum cement content of 5.2 sacks/cubic
.yards.
3. 'The maximum water content should be 7.0 Gals/cubic yards in order to
,maintain an acceptable water to cement ratio.
4 . Maximum slump at which the concrete should be placed should not exceed
:more than six inches.
5. Maximum size of aggregate for concrete should be between three
quarters to one and one-half inches (3/4" to 1 1/2").
6 . Please note that every gallon of water added to the concrete above the
design mix, will result in the loss of one inch (1") slump and 200 psi
in compression strength. (ACI Manual and Practices of Concrete).
7.
Delivery time,
ninety minutes.
Standard #26).
including unloading of concrete shall, not exceed
(ACI Manual and Practices of Concrete and UBC
8 . Slabs must be cured using Hunt's curing compound, or any approved
equivalent curing method. (ACI 318, Chapter 26, 1982 UBC).
9. Reinforcement should be placed within three inches from the bottom or
according to the specifications outlined in Section 2607(h), 1988 UBC.
10. Control joints should be placed typically on ten foot centers for four
inch nominal slabs in order to reduce excessive cracking. Formula for
joint spacing = 2.5 x slab thickness.
11. Concrete shall not be placed at temperatures exceeding the recommended
limits (50 degrees F winter, 100 degrees F summer), (ACI306).
12. ~The subgrade should be relatively moist prior to placing concrete
slabs-on-grade, (ACI318).
13. Daily information must be kept on file containing concrete tickets,
time of pour, temperature, and other factors effective concrete
placement and finishing.
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14. If slabs are poured at different times, construction joints are
necessary.
15. All fluffy loose material generated by trenching must be removed or
recompacted properly under the supervision of an engineer of this firm
16. Excessive moisture should not be allowed within five feet of any
concrete foundation and slab area, unless proper design factors have
been introduced into consideration.
17. . Any additional specifications concerning curing of the concrete must
be provided by the concrete ready mix company or the supplier.
18. It is the responsibility of the owner, the contractor, and/or the
supplier to inform the soil engineer of any unsuitable conditions
prior to placing concrete. All such conditions must be reported in
writing for additional recommendations or corrections.
19. Prior to concrete pour, the contractor, owner and builder must ensure
all recommendations provided are completely carried out and approved
by this firm.
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