HomeMy WebLinkAboutTract Map 3883 Lot 506 Preliminary Soils
PRELIMINARY SOIL INVESTIGATION
for
Lot 506; TR 3883
APN: 919-332-003
30625 Del Rey
Temecula, California
March 5, 2001
Prepared for:
Mr. Fred Jewell
750 Portola Terrace
Los Angeles, California 90042-6018
(0) 909/304-0400 x 212
(c) 909/334-6830
Prepared by:
Gunvant Thakkar, P.E.
45712 Classic Way
Temecula, California 92592
(909) 676-7541
RECEIVED
MAR 6 2001
CITY OF TEMECULA
ENGINEERING DEPARTMENT
\
GUNVANT THAKKAR,
PROFESSIONAL ENGINEER
45712 Classic Way, Temecula, California 92592 (909)676-7541
,
March 5, 2001
Mr. Fred Jewell
750 Portola Terrace
Los Angeles, California 90042-6018
Phone: (0) 304-0400 x 212
(c) 334-6830
Subject:
Preliminary Soil Investigation
Lot 506; TR 3883
APN: 919-332-003
Temecula, California
Dear Mr. Jewell:
In accordance with your request and authorization, this report presents
the results of our soils investigation of the subject property located on Del Rey
Road, Temecula, California (see Site Location Map Figure 1). The purpose of
the study was to evaluate the existing soil condition on the subject property
relative to the proposed development.
1. Site Description
The property is located on Del Rey Road, Temecula, Riverside County,
California, and consists of approximately 0.6 acres, and is mostly flat as
the pad has been rough graded.
2. Proposed development
It is our understanding that the property is proposed to have a single
residence with attached garage. The site is mostly flat. The highest point
on the property is the north portion and declines to approximately a 12.5
percent grade. Therefore, only a moderate amount of grading will be
required to create a pad. The grading plan has been prepared by Gunvant
z.
Thakkar, P.E., Temecula, California. It is our understanding that one or
two story buildings utilizing wood frame and/or masonry block
construction, with slabs-on-grades and continuous footings are proposed.
Building loads are assumed to be typical for residential structures. It is
also our understanding that sewage disposal will be accommodated by a
subsurface sewage disposal system.
3.
Field Studies
.
The field studies conducted during our evaluation of the property
consisted of the following:
a. review of available geotechnical data in our files
pertaining to the site.
b. field reconnaissance by a soils engineer.
c. laboratory testing of selected representative soil
samples.
d. preparation of this report presenting our
findings, conclusions, and recommendations.
4. Subsurface Investiaation Laboratorv TestinQ
One exploratory trench was excavated in order to determine the
conditions of the near-surface natural material. The sample was logged,
in-place moisture and density of the exposed materials was recorded, and
representative bulk and relatively undisturbed sample was collected for
laboratory testing.
5. Laboratorv Testina
a. Soil Classification
Soils were classified visually according to the unified soils
classification system. The soils classifications are shown on the
trench logs (Appendix A).
b. Soils Density
The field moisture content and dry unit weights were determined for
the undisturbed sample of the soils encountered in the trench. The
dry unit weight was determined in pound per cubic foot and the
field moisture content was determined as a percentage of the dry
~
unit weight. The results of this test are shown on the trench log
(Appendix A).
6. General Site GradinQ
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.
7. Ground Water
No groundwater or evidence of seepage was encountered within the
exploratory trench at the time and location of exploration. However, other
conditions may be there that would effect the entire proposed project and
final plans and specifications.
8. Consolidation 1 Collapse Potential
Considering the on-site low in-place densities, the susceptibility for
consolidation 1 collapse under the proposed load is anticipated within the
upper three feet throughout the site.
9. Conclusion and Recommendation
a. General
1. Based on our field exploration, laboratory testing, and our
soil engineering analysis, it is our opinion that the project site
is suited for the proposed development from a soils
engineering viewpoint. The recommendation presented
below should be incorporated in the design, grading, and
construction considerations.
2. Soils engineering and compaction services should be
provided during grading to aid the contractor in removing
unsuitable soils and in his effort to compact the fill.
3. Ground water is not expected to be a factor in the
development of the site. However, caving and sloughing
may be anticipated to be a factor in all subsurface
excavation and trenching.
A.
4. At the time of preparation of this report, the proposed
finished pad grades, location of any structures, type of
structures and loadings were all of a preliminary planning
nature.
5. General earthwork and grading guidelines are provided at
the end of this report as Appendix C.
b. DemolitionlGrubbing
1. Existing shrubs, and any miscellaneous construction
materials and debris should be removed from the site.
2. Any previous foundation, cesspools, septic tanks, leach
fields, or other subsurface structures, uncovered during the
recommended removal should be observed by the soils
engineer so that appropriate remedial recommendations can
be provided.
3. Cavities or loose soils (including all trenches) remaining after
demolition and site clearance should be cleaned out,
inspected by the soils engineer, processed and replaced
with a fill that has been moisture conditioned to at least
optimum moisture content and compacted to at least 90 %
of the laboratory standards.
c. Fill placement
1. Fill material should be brought to at least optimum moisture,
placed in thin 6 to 8 inch lifts, and mechanically compacted
to obtain minimum relative compaction of 90 percent of the
laboratory standard.
2. Fill material should be cleansed of major vegetation and
debris prior to placement.
3. Any oversized rock material greater than 10 inches in
diameter should be placed under the recommendations and
supervision of this soils engineer.
d. 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 12 inches below the final approved grade with
'5
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 0.36 may be 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.
e. Concrete Slabs on Grade
Sufficient fine grained materials exist within near surface earth
materials to possibly create moisture problems. Therefore, we
recommend that a moisture barrier be placed under any concrete
slabs that might receive a moisture-sensitive floor covering. This
moisture barrier should consist of a 10-mil polyethylene vapor
barrier sandwiched between a one inch layer of sand, top and
bottom, to prevent puncture of the barrier and enhance curing of
the concrete. Nominal reinforcement of the slabs with light six inch
by six inch, 10 gauge/10 gauge welded wire fabric is advisable.
Slabs should be designed for any special loads, such as
construction crane loads, if warranted. Large slabs should have
crack control joints on 10 foot centers and small slabs should have
them on five foot centers.
f. Expansive Soils
Based on visual observations, lab testing, and field classifications,
there does not appear to be any soils within the upper six feet of
the surface which appear highly expansive; however, if fill materials
are imported to the site, it is recommended that expansion testing
be performed upon the completion of grading to evaluate any
expansion potentials.
g. Earthwork Shrinkage and Subsidence
When the existing less dense materials is regraded to compacted
fill standards, earthwork shrinkage should be estimated to range
between 9 and 17 percent (based on an average of 92 percent
'"
relative compaction), for a total 4 foot over-excavation below
existing grade. This variation is due to the large difference in in-
place densities obtained during our soil sampling. It should be
noted that these estimates are exclusive of any losses due to any
possible buried substructures (i.e. septic tanks, pipes, etc.) or
localized fill pockets. Earthwork operations should cause only a
nominal subsidence of approximately 0.1 foot or less.
h. Lateral Loads
,
Lateral loads in the near surface soils are:
Active
35 pounds per square foot per foot of
soil depth (psflft)
64 psflft
250psf/ft - wood shoring
350psf/ft - concrete footings
At Rest
Passive
Active means movement of the structure away from the soil. At
rest, means the structure does not move relative to the soil (such
as a loading dock or building wall). Passive means the structure
moves into the soil. The coefficient of friction between the bottom
of the footings and the native soil may be taken as 0.35.
I. Trench Stability
The near surface soil is a depth of 6 feet may not stand vertically
for more than several hours when excavated as tension cracks or
joints may be locally found in the soils associated with past seismic
activity from nearby major faults. Trenches in excess of 5 feet in
depth should have the sides laid back at 1: 1 or shored in
accordance with OSHA requirements.
j. General Site Grading
1. General
All grading should be performed in accordance with the
standard grading and earthwork specifications outlined in
Appendix C, or unless otherwise modified in the text of this
report.
1.
2. Clearing and Grubbing
The site should be clear of any vegetation and hauled off
site. Any and all of the debris, and all the deleterious and
oversized material should be carefully removed and also
hauled off site. The soil should be over-excavated as
described below.
3. Site Preparation
The site will require removal of loose natural soils and fill
materials (if found), based on field observation and
laboratory testing.
On all buildings that may have columns extending into the
native materials, no preparations of soil is necessary when
in place densities indicate 85 percent relative compaction
beneath the footings providing all foundations are in natural
soils.
4. Placement of Compacted Fill
Compacted fill is defined as that material which will be
added to the site andlor replaced in the areas of removal,
due to relatively low density soils. All fill should be
compacted to a minimum of 90 percent based upon
maximum density obtained in accordance with ASTM
D1557-78 procedure. The area to be filled will be prepared
in accordance with preceding section 3.
5. Review of Grading Plan and Specifications
We recommend that the soils engineer have the opportunity
to review the final grading plan and the specifications to
ensure that they include the item of the soil report for the
benefit of the owner and the contractor, in particular, to
verify the over-excavation depth and elevation, if proposed
grade elevations are different from that of existing ground
surface present at the time of our field investigations.
6. Pre-Job Conference
Prior to the commencement of grading, a pre-job conference
should be held with the representative of the owner,
developer, contractor, architect, andlor engineer, and soil
~
engineer, in attendance. The purpose of this meeting will be
to clarify any questions relating to the intent of the grading
recommendations and to verify that the project specifications
comply with the recommendations of this report.
7. Testing and Inspection
During grading, density testing should be performed by a
representative of the soils engineer in order to determine the
degree of compaction being obtained. Where testing
indicates insufficient density, additional compactive efforts
shall be applied with the adjustment of moisture content,
where necessary, until at least 90 percent relative
compaction is obtained. The subgrade of the over-
excavations and the footing excavations should be inspected
and improved by us prior to placement of fill andlor concrete.
The maximum dry density shall be determined in
accordance with ASTM D1557-78 procedure.
8. Summary
All grading should, at a minimum, follow the "Standard
Grading and Earthwork Specifications" as outlined in
Appendix C, unless otherwise modified in the text of this
report. The recommendations of this report are based on the
assumptions that all footings will be founded in properly
compacted fill soil or natural dense soil as approved by the
soils engineer. All footing excavations should be inspected
prior to the placement of concrete in order to verify that
footings are founded on satisfactory soil and are free of
loose and disturbed materials. All gradings and fill
placement should be performed under the testing and
inspection of a representative of the soils engineer.
9. Investigation Limits
The materials encountered on the project site and utilized in
the laboratory are believed representative of the total area;
however, soils materials may vary in characteristics between
test excavations. Since our investigation is based upon the
site materials observed, selective laboratory testing, and
engineering analysis, the conclusions and recommendations
are professional opinions. It is possible that variations in soil
conditions could exist beyond the points explored in this
investigation. Also, changes in the ground water condition
could occur sometime in the near future due to variations in
<\
temperature, regional rainfall, and other factors. Should
conditions be encountered during grading that appear to be
different than those indicated by this report, the soils
engineer should be notified. These opinions have been
derived in accordance with current standards of practice and
no warranties are expressed or implied.
We sincerely appreciate this opportunity to be of service. If you have any
questions. concerning this report, please contact us at 909/676-7541.
\0
Enclosures:Figure 1: Site location map
Plate 1: Trench location map
Appendix A: Exploratory trench logs
Appendix B: Laboratory test data
Appendix C: Standard grading and earthwork specs.
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LEGEND I
APPROXIMATE TEST LOCATION
DATE: J-5'- 01
TRENCH LOCATION MAP
PLATE: I
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Appendix A
Exploratory trench log
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Appendix B
Laboratory test data
~
GUNVANT THAKKAR, PROFESSIONAL ENGINEER
45712 Classic Way, Temecula, California 92592 (909) 676-7541
Mr. Fred Jewell
Maximum Density
c
Optimum Moisture Content
%
127.1
10,5
\1.
1 I BORING/TRENCH No....LSAMPLE No.LDE
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SOIL ClASSIACATlON
1\
METHOD: ASTM 01557
PROCEDURE: A
PREPARATION: 'MOIST
RAMMER:
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\ MECHANICAL -
1\1 \
1\ SIEVE DATA:
\1 , RETAINED ON No. 4
"'11.1\
"" RETAINED ON 3/8 in,
11.
1\ xt RETAINED ON 3/4 in.
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,\I I\. MAXIMUM DRY UNIT W
ft.1
" OPTIMUM MOISTURE
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______ ZERO AIR VOIDS
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150
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PTH
145
ASTM 0698 0
B 0 cO
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140
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RCULAR 0
SECTOR 0
135
130
125
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CURVES
105
100
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95
90
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5
10 15 20 25 30
MOISTURE CONTENT (;>; OF DRY WEIGHT)
35
DATE:
Z!Zi/fj ,
MAXIMUM DRY UNIT WEIGHT
flWEN\)\'i:
PROJECT NO,:
ASTM 01557/ASTM 0698
pfCe]) .rEtl/5t-t.
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Appendix C
Standard Grading and Earthwork Specs.
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STANDARD GRADING AND EARTHWORK SPECIFICATIONS
These specifications present our recommendations for grading and earthwork.
No deviation from these specifications should be permitted, unless where
specifically superseded in the geotechnical report of the project or by written
communications signed by the geotechnical consultant. Evaluation performed by
the consultant during the course of grading may result in subsequent
recommendations which could supersede these specifications or the
recommendations of the geotechnical report.
1,0 General
1,1 The geotechnical consultant is the owners or developers
representative on the project. For the purpose of these
specifications, observations by the geotechnical consultant include
observations by the soils engineer, geotechnical engineer,
engineering geologist, and those performed by persons employed
by, and responsible to the geotechnical consultant.
1,2 All clearing, site preparations, or earthwork performed on the
project shall be conducted and directed by the contractor under the
supervision of the geotechnical consultant.
1.3 The contractor should be responsible for the safety of the project
and the satisfactory completion of all grading. During grading, the
contractor should remain accessible.
1.4 Prior to commencement of grading, the geotechnical consultant
shall be employed for the purpose of providing field, laboratory, and
office services for conformance with the recommendations of the
geotechnical report and these specifications. It will be necessary
that the geotechnical consultant provide adequate testing and
observations so that he may determine that the work was
accomplished as specified, It shall be the responsibility of the
contractor to assist the geotechnical consultant and keep him
apprised of work schedule and changes so that he may schedule
his personnel accordingly,
1,5 It should be the sole responsibility of the contractor to provide
adequate equipment and methods to accomplish the work in
accordance with applicable grading codes or agency ordinance,
these specifications, and the approved grading plans. If, in the
opinion of the geotechnical consultant, unsatisfactory conditions,
such as questionable soil, poor moisture condition, inadequate
compaction, adverse weather, etc. are resulting in a quality of work
less than required in these specifications, the geotechnical
1P
consultant will be empowered to reject the work and recommend
that construction be stopped until the conditions are rectified.
1,6 It is the contractor's responsibility to provide access to the
geotechnical consultant for the testing andlor grading observation
purposes. This may require excavation of the test pits andlor the
relocation of grading equipment.
1.7 A final report shall be issued by the geotechnical consultant
attesting to the contractor's conformance with these specifications.
2,0 Site Preparation
2.1 All vegetation and deleterious material shall be disposed of off site.
This removal shall be observed by geotechnical consultant and
concluded prior to fill placement.
2.2 Soil, alluvium, or bedrock materials determined by the geotechnical
consultant as being unsuitable for placement in compacted fills
shall be removed by the site or used in landscape areas as
determined by the geotechnical consultant. Any material
incorporated as a part of compacted fill must be approved by the
geotechnical consultant prior to fill placement.
2.3 After the ground surface to receive fill has been cleared, it shall be
scarified, disked, or bladed by the contractor until it is uniform and
free from roots, hollows, hummocks, or other uneven features
which may prevent uniform compaction,
The scarified ground surface shall then be brought to optimum
moisture, mixed as required, and compacted as specified, If the
scarified zone is greater than 12 inches in depth, the excess shall
be removed and placed in lifts restricted to 6 inches.
Prior to placing fill, the ground surface to receive fill shall be
observed, tested, and approved by the geotechnical consultant.
2.4 Any underground structures or cavities, such as cesspools,
cisterns, mining shaft, tunnels, septic tanks, wells, pipelines, or
others, are to be removed or treated in the manner prescribed by
the geotechnical consultant.
2,5 In cut fill transition lots and where cut lots are partially in soil,
colluvium, or unweathered bedrock materials, in order to provide
uniform bearing conditions, the bedrock portion of the lot, extending
1A
a minimum of 5 feet outside of building line, shall be over-
excavated a minimum of 3 feet and replaced with compacted fill.
3,0 Compacted Fills
3.1 Materials to be placed as fill shall be free of organic matter and
other deleterious substances, and shall be approved by the
geotechnical consultant. The soils of poor gradation, expansion, or
strength characteristic shall be placed in areas designated by the
geotechnical consultant or shall be mixed with other soils to serve
as satisfactory fill materials, as directed by the geotechnical
consultant.
3.2 Rock fragments less than 6 inches in diameter may be utilized in
the fill, provided:
a, They are not placed in concentrated pockets.
b. There is sufficient percentage of fine
grained materials to surround the rocks,
c, The distribution of rocks is supervised by
the geotechnical consultant.
3.3 Rocks greater than 6 inches in diameter shall be taken off site or
placed in accordance with the recommendation of the geotechnical
consultant in areas designated as suitable for rock disposal.
3.4 Materials that are spongy, subject to decay, or otherwise
unsuitable, should not be used in the compacted fill.
3.5 Representative samples of materials to be utilized as compacted fill
shall be analyzed by the laboratory of the geotechnical consultant
to determine their physical properties, If any material other than
that previously tested is encountered during grading, the
appropriate analysis of this material shall be conducted by the
geotechnical consultant as soon as possible.
3,6 Materials used in the compacting process shall be evenly spread,
watered, processed, and compacted in thin lifts not to exceed 6
inches in thickness, to obtain a uniformly dense layer. The fill shall
be placed and compacted on a horizontal plane unless otherwise
approved by the geotechnical consultant.
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3,7 If the moisture content or relative compaction varies from that
required by the geotechnical consultant, the contractor shall rework
the fill until it is approved by the geotechnical consultant.
3,8 Each layer shall be compacted to 90 percent of the maximum
density, in compliance with the testing method specified by the
controlling government agency or ASTM 1557-78, whichever
applies,
,
If compaction to a lesser percentage is authorized by the
controlling governmental agency because of specific land use of
expansive soil condition, the area to receive fill compacted to less
than 90 percent shall either be delineated on the grading plan or
appropriate reference made to the area in the geotechnical report,
3,9 All fill shall be keyed and benched through all topsoil, colluvium,
alluvium, or creep materials, into sound bedrock or firm materials
where the slop receiving fill exceed a ratio of 5 horizontal to 1
vertical, in accordance with the recommendations of the
geotechnical consultant.
3.10 The key for side hill fills shall be a minimum width of 15 feet within
bedrock or firm materials, unless otherwise specified in the soils
report,
3,11 Sub drainage devices shall be constructed in compliance with the
ordinance of the controlling government agency or with the
recommendations of the geotechnical consultant.
3,12 The contractor will be required to obtain a relative compaction of 90
percent out of the finished slope face of fill slopes, buttresses, and
stabilization fills. This may be achieved by either overbuilding the
slope and cutting back to the compacted core, by direct compaction
of the slope and cutting back to compacted core, by direct
compaction of the slope face with suitable equipment, or by any
other procedure which produces the required compaction approved
by the geotechnical consultant.
3.13 All fill slopes should be planted or protected from erosion by other
methods specified in the geotechnical report,
3.14 FiII-over-cut slope shall be properly keyed through topsoils,
colluvium, or creep materials into rock or firm materials, and the
transition shall be stripped of all soils prior to placing fill.
1,.,A..
4,0 Cut Slope
4.1 The geotechnical consultant shall inspect all cut slopes or vertical
intervals not exceeding 10 feet.
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4,2 If any conditions not anticipated in the geotechnical report, such as
perched water, seepage, lenticular, or confined strata of potentially
adverse nature, unfavorably-inclined bedding, joints, or fault planes
encountered during grading, these conditions shall be analyzed by
the engineering geologist, and recommendations shall be made to
mitigate this problem,
4.3 Cut slopes that face in the same direction as prevailing drainage
shall be protected from slope wash by a non-erodible interceptor
swell placed at the top of the slope,
4.4 Unless otherwise specified in the geotechnical report, no cut slopes
shall be excavated higher or steeper than that allowed by the
ordinance of controlling governmental agencies.
4,5 Drainage terraces shall be constructed in compliance with the
ordinances of controlling governmental agencies, or with the
recommendations of the geotechnical consultant or engineer
geologist.
5.0 Trench Backfills
5,1 Trench excavations for utility pipes shall be backfilled under the
supervision of the geotechnical consultant.
5,2 After the utility pipe has been laid, the space under and around the
pipe shall be backfilled with clean sand or approved granular soil to
a depth of at least 1 foot over the top of the pipe. The sand backfill
shall be uniformly jetted into place before the controlled backfill is
placed over the sand.
5,3 The onsite materials, or other soils approved by the geotechnical
consultant, shall be water and mix as necessary prior to placement
in lifts over the sand backfill.
5.4 The controlled backfill shall be compacted to at least 90 percent of
the maximum laboratory density as determined by ASTM D1557-78
or the controlling governmental agency.
5,5 Fill density test and inspection of the backfill procedures shall be
made by the geotechnical consultant during backfilling to see that
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proper moisture content and uniform compaction is being
maintained, The contractor shall provide test holes and exploratory
pits as required by the geotechnical consultant to enable sampling
and testing.
6,0 GradinQ Control
6.1 Inspections of the fill placement shall be provided by the
geotechnical consultant during the progress of grading.
6.2 In general, density tests should be made at intervals not exceeding
2 feet of fill height or every 500 cubic yards of fill placed, This
criterion will vary, depending on the soil condition and size of the
job. In any event, an adequate number of fill density tests shall be
made to verify that the compaction is being achieved.
6.3 Density tests should also be made on the surface material to
receive fills as required by the geotechnical consultant.
6,4 All cleanup, processed ground to receive fill, key excavations,
subdrains, and rock disposals should be inspected and approved
by the geotechnical consultant prior to placing any fill. It shall be
the contractors responsibility to notify the geotechnical consultant
when such areas are ready for inspection.
7,0 Construction Consideration
7,1 Erosion control measures, when necessary, shall be provided by
the ,contractor during grading and prior to the completion and
construction of permanent drainage control.
7.2 Upon completion of grading and termination of inspectors by the
geotechnical consultant, no further filling or excavating, including
that necessary for footings, foundations, large tree wells, retaining
walls, or other features shall be performed without the approval of
the geotechnical consultant.
7.3 Care shall be taken by the contractor during final grading to
preserve any berms, drainage terraces, interceptor swells, or other
devices of permanent nature on or adjacent to the property.
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