HomeMy WebLinkAboutParcel Map 18098 Parcel 1-2 Prelim Soils Report
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W. C. HOBBS, CONSULTING ENGINEER
39281 VIA PAMPLONA
MURRIETA, CAUFORNIA 92563
(909) 696-7059
Date: July 1, 2001
Project No: 0105(}.1
Mr. Duane Walston
P.O. Box 264
Hemet, California 92546
;Subject:
Preliminary Soli Engineering Evaluation,
for Proposed Residence Located at Jeramie Drive,
Parcels 1 and 2 of PM 18098, City of Temecula, California
:Dear Mr. Walston,
'Pursuantto your autholization and a requirement by the City of Temecula, a limited soil engineering
!evaluation was conducted on the subject lot to determine the distribution and engineering
:characteristics of earth materials present The results of field exploration, together with the results of
Ithe laboratory tests, are summarized in the attached appendix.
:Additional information provided herein includes preliminary foundation design for proposed
'residential construction.
IAccompanying IMaps and Appendices
'Attached Appendix A, Summary of Laboratory and Field Test Results
:Attached Appendix S, General Earthwork and Grading Specifications
; Plate 1, Trench Location Map
: Scope of Work
'The scope of work performed for this study included the following:
'1. Observation of a natural lot,
; 2. Excavation of exploration trenches into the subject site to observe the existing soil conditions
and recover samples.
3. Laboratory testing, and;
, 4. Preparation of' this report including conclusions and recommendations pertinent to the
proposed construction.
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Mr. Duane Walston, Parcel Map 18098, Jeramle Rd., City of Temecula Page: 2
Project No: 01050.1
Site Description
I.
The site is roughly rectangular in shape, fronting 500 feet along the south side of John Warner Rd.
and 310 feet along Jeramie Drive. The site is currently not graded with the exception of a minor
travel way for access to the top of the ridge for viewing the property. The site is a ridge line extending
from the eastem comer to the westem comer, descending westerly. A ravine drains south along the
southeast property line toward Jeramie drive. Presently, the site is covered with a nominal growth of
weeds and grasses that were recently cut. No visible signs of erosion were noted.
Field Work
Field work on the site consisted of observation an excavation made by a drilling rig for the purpose
of recovering samples of representative earth materials for laboratory testing. The results of these
tests are contained in the attached Appendix A. Additionally, a reconnaissance of the nearby area
was conducted inorderto obtain information pertinent to the site. A log of the excavation is included
in thLos section and is as follows. From the ground surface to a depth of 2.5 feet there is a colluvium
type topsoil, brown, dry, loose to medium dense, consisting of a silty fine to medium sand. From 2.5
feet to 20 feet, this consists of the Pauba Formation sandstone. It is a silty fine to medium sand,
damp to moist, medium dense at this location. The location of the exploration boring is indicated on
the Plate 1 attached at the back of this report.
Observation and testing of the excavations indicated that the existing materials were of moderate to
high density in place with no visible pores, and is dry at the surface. Location of test boring is
indicated on Plate 1, Trench Location Map Observation of the earth materials indicates a thin mantle
of top soil, transitioning quickly Pauba Formation Bedrockata depth of approximately 1 to 2feet The
bedrock is moderately dense to dense, moist, non porous to the extent of the trench. The drilling rig
excavated to a depth of 20 feet below the ground surface with no difficulty. Several other areas were
excavated on the site with similar results, including the toes of slopes and the flat areas.
Laboratory Testing
The maximum dry density and optimum moisture content of the soil was determined in accordance
with ASTM test designation D 1557-82. The expansion index testing should be conducted on a
representative sample at the completion of rough grading in order to determine the expansion
potential of the near surface soils in the vicinity of proposed foundations. The expansion index test
should be conducted in accordance with UBC 29-2.
W. C. HOBBS, CONSULTING ENGINEER
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Mr. Duane Walston, Parcel Map 18098, Jeramle Rd., City of Temecula Page: 3
Project No: 01050-1
CONCLUSIONS AND RECOMMENDATIONS
Conclusions
The development of the, site for single or multi-story residential construction is both feasible and safe
from a geotechnical standpoint provided that the recommendations contained herein are
implemented during design and construction.
1. The site is essentially untouched, graded only at the westem and southam edges for roadway
slopes and construction.
2. The soil is observed to be dense in place with the exception of the upper 1 to 2 feet.
3.0bservation, classification, indicate that the near surface soils have a low to moderate expansion
potential.
4. Building setbacks indicated in County Geologic Report No. GR279 should be observed during site
development.
Recommendations
The recommendations contained herein are contingent upon W. C. Hobbs, Consulting Engineer or
his assigns providing the services listed in the Construction section in order to confirm design
assumptions and review the field conditions of any excavations for possible anisotropic properties.
If observation indicates that the conditions are different than those indicated in this report, additional,
or modifications to the, recommendations may become necessary.
Site Grading
'norder to provide proper support for building foundations, remedial grading will not be required.
Proposed grading consists of creating a driveway, pad and foundation areas and or the balance
placement of fills on th~ site for a pad area in the vicinity of the proposed residence and driveway.
According to the proposed grading plan prepared by this firm, some exporting of soils is anticipated
also. All grading and retaining wall backfills should be placed in accordance with minimum standards
presented a the back of this report, Appendix B, Standard Specilications for Earthwork Construction.
Grading should consist of the removal of the upper 1 to 2 feet of alluvial soils in the building area and
areas that will receive fills. This removal area should extend an equal distance away from the lowest
outside edge of the foundations as the final thickness of fill in the proposed area, or a minimum of 5
feet, whichever is the g~ater. Final determination for the depth of excavation shall be made in the
field during grading operations. It is possible that additional excavations may result in more or less
excavation due to varying depths of colluvial and alluvial soils.
W. C. HOBBS, CONSULTING ENGINEER
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Mr. Duane Walston, Parcel Map 18098, Jeramie Rd., City of Temecula Page: 4
Project No: 01050-1
Recommendations, continued
Bearing Value and Footing Geometry
A safe allowable tJearing value for foundations embedded into native bedrock materials or property
compacted fill is 2000 psf. This value may be increased at the rate of 100 pst per foot of depth and
100 psf per foot of width over the minimums, but should not exceed 2500 pst. Continuous footings
should have a minimum width of 12 inches and depth of 18 inches and conform to the minimum
criteria of the UBC for single and or multistory construction for moderately expansive soils. The use
of isolated column footings is not discouraged, however, where utilized, should have a minimum
embedment of 18 inches below lowest soil grade. The minimum distance of the bottom of footings
on the outside edge and the native slope face is 8 feet.
Settlement
The bearing value recommended above reflects a total settlement of 0.5" and a differential
settlement of 0.5". Most of this settlement is expected to occur during construction and as the loads
are being applied.
,Concrete Slabs
~II concrete slabs on grade should be 4 inches thick. They should be underlain by 2 inches of sand
or gravel. Areas that are to be carpeted or tiled, or where the intrusion of moisture is objectionable,
should be underlain by 6 mil visqueen property protected from puncture with an additional 1 inch of
sand over it This anangement of materials would result in a profile downward of concrete, 1 inch of
sand, 6 mil visqueen, 2 inches of sand and subgrade soil. Contractors should be advise that when
pouring during hot or windy weather conditions, they should provide large slabs with sufficiently deep
weakened plane joints to inhibit the development of irregular or unsightly cracks. Also, 4 inch thick
slabs should be jointed, in panels not exceeding 12 feet in both directions to augment proper crack
direction and development.
:Reinforcement
:Continuous footings should be reinforced with a minimum of one number 4 steel bar placed at the
ltop and one at the bottom. Slabs should be reinforced with a minimum of number 3 steel bars
:placed at the center of thickness at 18-inch centers both ways or welded wire fabric equivalent to
! 1 OX1 0 10/10 may be used. It is understood that the sectional values for the two schedules are
:different, and is of no design concem. The steel bars have been proven to have a better performance
'history and selection is up to the builder. Additional requirements may be imposed by the structural
engineering design.
W. C. HOBBS, CONSULTING ENGINEER
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Mr. Duane Walston, Parcel Map 18098, Jeramle Rd., City of Temecula Page: 5
Project No: 01050-1
Recommendations, continued
Retaining Walls
Retaining walls should be designed to resist the active pressures summarized in the following table.
The active pressure is normally calculated from the lowermost portion of the footing to the highest
ground surface atthe back of the wall. The active pressures indicated in the table are equivalent fluid
densities. Walls that are not free to rotate or that are braced at the top should use active pressures
that are 50% greater than those indicated in the table.
RETAINING WALL DESIGN PRESSURES
Slooe of
adiacent ground
Active Pressure
Passive Pressure
2:1
30pcf
40pcf
300pcf
200 pcf
LEVEL
These pressures are for retaining walls backfilled with noncohesive, granular materials and provided
with drainage devices ,such as weep holes or subdrains to prevent the build-up of hydrostatic
pressures beyond the design values. It is imperative that all retaining wall backfills be compacted to
a minimum of 90, percent relative compaction in order to achieve their design strength. Failure to
provide proper drainage and minimum compaction may result in pressures against the wall that will
exceed the design values indicated above. Surface waters should be directed away from retaining
wall backfill areas so as not to intrude into the backfill materials.
,Lateral Loads
The bearing value of the soil may be increased by one third for short duration loading (wind,
seismic). Lateral loads may be resisted by passive forces developed along the sides of concrete
:footings or by friction along the bottom of concrete footings. The value of the passive resistance for
level ground may,be computed using an equivalent fluid density of 300 pcffor level ground. The total
force should not exceed 3000 pst. A coefficient of friction of .40 may be used for the horizontal
soiVconcrete interface for resistance of lateral forces. If friction and passive forces are combined,
then the passive .vaIues should be reduced by one third.
W. C. HOBBS. CONSULTING ENGINEER
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Mr. Duane Walston, Parcel Map 18098, Jeramle Rd., City of Temecula Page: 6
Project No: 01050-1
Recommendations, continued
Fine Grading
Fir:le grading of areas outside of the residence should be accomplished such that positive drainage
exists awayfrom all footings. Run-off should be conducted off the property in a non erosive manner
toward approved:drainage devices at the street or the rear of the property per approved plans.
Construction
A soil engineer should be present during the excavation of the foundations, as well as earthwork
construction, to test and. or confirm the conditions encountered during this study. It is recommended
to have the foundation excavations observed by a soil engineer prior the placement of construction
materials in them as consequential changes and differences may exist throughout the earth
materials on the site. It may be possible that certain excavations may have to be deepened slightly
ff earth materials are found to be loose or weak.
Grading Plan :Review
The final grading plan should be reviewed prior to the grading to verify that the recommendations of
this report are implemented for remedial grading and to assist in verifying extent and depth of
excavations based on :actual building placement and elevation with respect to existing ground
surface. This review is additional and beyond the scope of this report. Supplementally, it should be
reViewed in conjunction with the provisions of County Geologic Report No. GR279
W. C. HOBBS, CONSULTING ENGINEER
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Mr. Duane Walston, Parcel Map 18098, Jeramie Rd., City of Temecula Page: 7
Project No: 01050'1
CLOSURE
This evaluation was performed in accordance with generally accepted engineering practices. The
conclusions and recommendations contained in this report were based on the data available and the
interpretation of such data as dictated by our experience and background. Hence, our conclusions
and recommendations are professional opinions; therefore, no other warranty is offered or implied.
.The opportunity to be of service is appreciated. Should questions or comments arise pertaining to this
document, or if we may be of further service, please do not hesitate to call our office.
Hespectfully Submitted,
IW. C. HOBBS, CONSULTING ENGINEER
:Bm ,E42265
:CMI Engineer
Distribution:
IAttachments:
Addressee (4)
Appendix A - Summary of Laboratory and Field Test Results
Appendix B - General Earthwork and Grading Specilications
Plate 1, Trench Location Map
W. C. HOBBS, CONSULTING ENGINEER
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APPENDIX A
SUMMARY OF TEST RESULTS
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W. C. HOBBS, CONSULTING ENGINEER
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APPENDIX A
SUMMARY OF MAXIMUM DENSITY TEST RESULTS
Curve
Letter
Soil
Description
Maximum Optimum
Densitv ocf Moisture %
A
Silty SAND, fine to med..
Tan to Gray (SM)
127.5 10.8
Maximum density and optimum moisture determined in accordance with
test method ASTM D 1557-78.
W. C. HOBBS, CONSULTING ENGINEER
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APPENDIX B
GENERAL EARTHWORK AND GRADING SPECIFICATIONS
W. C. HOBBS, CONSULTING ENGINEER
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GENERAL EARTHWORK AND GRADING SPECIRCATlONS
1.0 : GENERAL INTENT
These specifications present;general procedures and requirements for grading and earthworn as shown on the approved grad'1TlQ plans,
incIucflTlQ preparation of areasto be filled, placement of fill. installation of subdrains, and excavations. The recommendations contained in the
geotechnical reportarea part of the earthwornand grading specifICations and shall supersede the provisions contained hereinafter inthecase
ofconfl'lCt Evaluations performed bytheconsultantduringthecourseofgrading mayresutt in new recommendations of the geotechnical report.
2.0 I EARTHWORK OBSERVATION AND TESTING
Prior to: the commencement of grading, a qualffied geotechnical consultant (soils engineer and engineering geologist, and their
repl'esentatives) shall be employed for the purpose of observing earthworn and testing the fills for conformance with the recommendations
of the geotechnical report and these specifications.
tt will be necessary that the consultant provide adequate testing and observation so that he may determine that the worn was accomp/'1Shed
as specified. tt shall be the responsibility of the contractor to assist the consultant and keep him apprised of worn schedules and changes so
that he may schedule his personnel accordingly.
tt shall be the sole responsibility of the contractor to provide adequate equipment and methods to accomplish the worn in accordance with
applicable grading codes or agency, ordinances, these specifICations and the approved grading plans. n in the opinion of the consultant,
unsatisfaclolycond'iIions, such as questionable soil, poor moisture condilion, inadequate compaction, adverse weather, etc., are resulting in
a quality of wor1< less than required in these specifICations, the consultant will be empowered to reject the worn and recommend that
construCtion be topped until the conditions are rectified.
Maximum dryclensitytes1s usedtodeterminethe degreeof compaction will be performed in accordance with the American SocietyofTesting
and Materi8lstes1s method ASTM D 1557-78.
3.0 ' PREPARATION OF AREAS TO BE RLLED
3.1 Clearing and Grubbing:, All brush, vegetation and debris shall be removed or piled and otherwise d'lSposed of.
3.2 Processing: Theexisting ground which is determinedto be satislactoryfor support offill shall bescarifiedto a minimum depth of6 inches.
Existingi9round which is not satisfactory shall be over excavated as specified in the following section.
Scarification shall continue until the soils are broken down and free of large clay lumps or clods and until the working surface is reasonably
uniform 'and free of uneven features which would inhibil unfform compaction.
3.3OverexcavaUon: Soft. dry, spongy, highlyfractured orotherwise unsuitable ground, extending tosuch adepththatthesurfaceprocessing
cannot adequately improve the condition, shall be over excavated down to firm ground, approved by the consultant
3.4 Moisture Conditioning: Over excavated and processed soils shall be watered, dried-back, blended, and/or mixed, as required to attain
a unffonn moisture content near optimum.
3.5 Recompaction: Over excavated and processed soils which have been properly mixed and moisture- cond'ilioned shall be recompacted
to a minimum relative compaction of 90 percent
3.6 Benching: Where fills are to be placed on ground with slopes steeper than 5: 1 (horizonlalto vertical units), the ground shall be stepped
or benched. The lowest bench shall be a minimum of 15 feet wide, shall be at least 2 feet deep, shall expose firm material, and shall be
approved by the consultant Other benches shall be excavated in firm material for a minimum width of 4 feet. Ground sloping fIatler than 5
: 1 ,shall: be benched or otherwise over excavated when considered necessary by the consu1tant.
3.7 Approval: All areas to receive fill, including processed areas, removal areas and toe-of.fill benches shall be approved by the consultant
prior to fill placement
W. C. HOBBS, CONSULTING ENGINEER
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4.0 I RLL MATERIAL
4.1 General: Material to be placed as fill shall be free of organic matter and other deleterious substances, and shall be approved by 1he
COI1Sultant Soils of poorgradation, expansion, or strength characteristics shall be placed in areas designated byconsullanl or shall be mixed
with other soil~ to serve as satisfactory fill material.
4.2,OversIze: Oversize material defined as rock, or other irreducible material with a maximum dimension greater than 12 inches, shaJ1 not
be buried or placed in fills, unless the loCation, materials, and <flSposaJ methods are specifICally approved by the consultant Oversize <f1SpOSal
operations ShaJI be such that nesting of oversize material does not occur, and such that the oversize material is completely surrounded by
con'Ipacted or densified fill. Oversize material shall not be placed within 10 feet vertically of finish grade or within 1he range of Mure ulirrties or
underground construction, unless specifICally approved by the consultant
4.3 Import: K importing of fill material is required for grading, the import material shall meet the requirements of Section 4. 1.
5.0 I RLI.. PLACEMENT AND COMPACTION
5.1 FIll Lifts: Approvedfill material shall be placed in areas prepared to receive fill in near-horizontallayers not exceeding 6 inches in compacted
thickness. The consullanl may approve thicker lifts ~ testing indicates the grading procedures are such that adequate compaction is being
achieved with lifts of greater thickness. Each layer shall be spread evenly and shall be thoroughly mixed during spreading to attain uniformity
of material land moisture in each layer.
5.2 RII Moisture: R1llayers at a moisture content less than optimum shall be watered and mixed, and wet fill layers shall be aerated by
scarification or shall be blended with,drier material. Moisture-<:onditioning and mixing of fill layers shall continue until the fill material is at a
uniform moisture content or near optimum.
5.3 Cor!1pac!lon of RII: After each layer has been evenly spread, moisture conditioned, and mixed, ~ shall be un~ormly compacted to not
less than 90 percent of maximum drydensity. Compaction equipment shall be adequately sized and shall be either speciflCallydesigned for
soil compaction or of proven'reliability, to efficiently achieve the specified degree of compaction.
5.4 RII Slopes: Compaction of s~ shall be accomplished, in add~ion to normal compacting procedures, by backfilling of slopes with
sheepsfoot rollers atfrequent increments of2to 3feetinfill elevation gain, orbyothermethods producing satisfactoryresulls. At1hecomplelion
of grading,' the relative compaction of the slope out to the slope face shall be atleasl90 percent.
5.5 Cor!1pac!lon Testing: Field tests to check the ill moisture and degree of compaction will be performed by the consultant The locatiOn
and frequency of tests shall be at the consultant's discretion. In general, the tests will be taken at an interval not exceeding 2 feet in vertical
rise and/or 1 ,000 cubic yards of embankment
6.0 SUBDRAlN INSTALLA1l0N
Subdrain systems, ~ required, shall be installed in approved ground to conform to the approximate alignment and details shown on the plans
orherein. Thesubdrain location ormaterialsshall not be changed ormodif1ed without the approval oftheconsullanl. Theconsultanl, howe\IeI',
m;ly recommend and upon approval, direct changes in subdrain line, grade or material. All subdrains should be surveyed for line and grade
after installation, and suffICient time shall be allowed for the surveys, prior to commencement of filling over the subdrains.
W. C. HOBBS, CONSULTING ENGINEER
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7.0 I EXCAVAllON
Ext;avation and cutslopes will be examined during grading. n directed by the consultant, further excavation or over excavation and refilfll1Q of
cut,areas shall be pertOllTled. ancVor remecfl8l grading of cut slopes shall be performed. Where fill-over-cut slopes are to be graded, unless
otherwise approved. the cut portion of the slope shall made and approved by the consullant prior to placement of materials for consll\Jction
of the fill! portion of the slope.
8.0 'TRENCH BACKFILL
8.1 j Supervision: Trench excavations for the utility pipes shall be backfilled under engineering supervision.
U Pipe Zone: After the utility pipe has been laid. the space under and around the pipe shall be backfilled with clean sand or approved
granulan soil to a depth of at least one foot over the top of the pipe. The sand backfill shall be un~ormly jetted into place before the c0ntr0lied
backfill is placed over the sand.
~F111 PiJacement: The onshe materials, orothersoils approved by the engineer, shall bewateredand mixed as necessarypriorto placement
in rifts overlhe sand backfill.
8.4,Compactlon: The controlled backfill shall be compacted to at least 90 percent of the maximum laboratory density as determined by the
ASTM compaction method descnbed above.
~Observatfon andTesUng: FIElId density tests and inspection of the backfill procedures shall be made by the soil engineerduringbackfilling
toQsee that the proper moislurecontent and un~orm compaction is being maintained. The contractor shall providetesl holes and exploratory
pits as required by the soil engineer to enable sampling and testing.
W. C. HOBBS, CONSULTING ENGINEER
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