HomeMy WebLinkAboutTract Map 32169 Geotechnical Report & Rough GradingI ~ pETRA
OFFICES IN THE COUNTIES OF
ORANGE • SAN DIEGO • RIVERSIDE • LOS ANGELES •
WILLIAM LYON HOMES, INC.
'I' 11800 Sterling Avenue, Suite A
, Riverside, California 92503
Attention: Mr. Mel Mercado
~~~'~$`.~^D
FEB ~ ~ z~~c5
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~ENT
January 4, 2005
J.N. 287-04
Subject: Geotechnical Report of Rough Grading, Tract 32169, Pl~ase II
~ Neighborhood 12, Pads 1 tl~rough 18 (Harvesto~z), City of
Temecula, Riverside County, California
References: 1) Leighton and Associates, Inc., 2003, As-Graded Report of Mass
Grading, Haiveston, Tract 29639-1, City of Temecula, Califoinia; for
Leimar Communities, Project No. 1 1023 1-006, dated Febiuary 5.
2) Peh-a Geotechnical, Ina, 2004, Post-Tensioned Foundation Design
Parameters, NeighUorhoods N-6 and N-12 witl~in Tract 29639-2,
Harveston, City of Temecula, Riverside County, Califomia,
J.N. 287-04, dated July 21.
This report presents a summary of tlie oUservation uid testing services provided by
Petra Geotecluucal, I~x. (Peh-a) during rough-grading operatiovs to develop
Phase II of NeigUborl~ood 12, Pads 1 throu;h 18 and associated interior drives
within Tract 32169 located in the CiCy of Temecula, Califomia. Conclusions aud
recommendations pertaining to tl~e suitability of tl~e grading for the proposed
residential conshuction are provided herein, as well as foundation-design
recommendations based on the as-graded soi] condiYions.
Initial grading of Tract 32169 was perfornled in conjunction with mass gradivg of
Tract 29639-1 and documented in the referenced as-graded report (Leighton, 2003).
Tl~e recent grading within Tract 32169 was perfonned in order to create 18 building
pads, interior drives and adjacent slopes for the proposed nmlti-family residential
units.
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PETRA GEOTECHNICAL, INC.
41640 Coming Place • Suite 107 . Murrieta . CA 92562 . TeC (909) 600-9271 . Fax: (909) 600-9215
WILLIAM LYON HOMES, INC.
TR 32169 Pads 1-18/Temecula
REGULATORY COMPLIANCE
January 4, 2005
J.N. 287-04
Page 2
Removal of existing weathered fill soils, cudfill transition lot overexcavations and
placement of compacted fill under the purview of this report l~ave been completed
under tl~e oUservation of and with selective testing Uy Petra. Tlle earthwork was
perfomied in accordance with the recommendations of the geotecluiical engineer
and the g-ading code of the City of Temecula.
The completed earthwork has been reviewed and it is considered adequate for the
construction now plamied. On the Uasis of our oUservations, as well as field and
]aboratory testing, the reconmlendations preseuted in this report were prepared in
confonna~ice with generally accepted professional engineering practices aud no
fiirther wairanty is implied nor made.
SUMMARY OF AS-GRADED SOIL AND GEOLOGIC CONDITIONS
As-Graded Conditions
Remedial site-specific gradiug ii~volved tlie removal of near-surface, weat6ered,
previously placed compacted fill, as well as bringing the overexcavated areas to
desi~l elevatioii with compacted fill. Tl~e compacted fills placed during this ~hase
of grading range in depth from approximately 1 to 15 feeY, with the deeper recent
fil] place~nent within Pads 8 fl~rough 11.
Groundwater
Gromidwater was not encountered during the rough grading of Tract 32169.
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WILLIAM LYON HOMES, INC.
TR 32169 Pads 1-18/Temecula
SUMMARY OF EARTHWORK
OB5ERVATION AND DENSITY TESTING
Clearing and Grubbing
January 4, 2005
J.N. 287-04
Page 3
Prior to grading, areas within the boundaries of the subject building pads were
cleared of deUris and vegetation that consisted of a minor ~rowth of weeds.
Ground Preparation
In areas to receive compacted fill, tl~e existing ~ound surface ~uas overexcavated to
depths of 2 feet or more Uelow existing grade. Within an existing desilting Uasin
located at the soutl~west ed~e of the tract, loose soils were removed to expose finn,
previously placed compacted fill.
Prior to placing fill, the exposed Uottom surfaces were observed aud detennined
suitable for fill placemenT by a representative of Petra. The exposed botYo~n
stufaces were then scarified to an appiroximate depth of 6 incl~es, watered as
necessaty to acl~ieve a moisture content near or sliglitly above opYimtun moisture
content and tl~en coulpacted Uy rolling witl~ a sheepsfoot tamper, loaded scrapers
uid/or rubUer-tired dozers.
Lot Overexcavation
To reduce the potential for differential settlement in Pads 1 through 3, where a cut-
to-fill trausitiou was exposed, the cut and shallow-fill portions of cut/fill transition
pads were overexcavated to a depth of 5 feet or more below finish grade. The pad
overexcavations extended beyond the perimeter edges of tl~e level pads.
Oversize Rock
No oversized rock was placed within engineered fills constructed during this phase
of grading.
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WILLIAM LYON HOMES, INC. January 4, 2005
TR 32169 Pads 1-18/Temecula J.N. 287-04
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Fill Placement and Testin~
Fill soils were placed in loose lifts approximately 6 to 8 inches thick watered or air-
dried as necessary to achieve near or slightly aUove optimun~ moisture conditions
and then compacted in-place. Compaction was achieved Uy wheel-rolling with a
sheepsfoot tamper, loaded scrapers and/or nibUer-tired dozers. The depths of fill
placed within the subject lots varied from approxiinately 1 to 15 feet.
Field density and moisture content tests were perfonned in accordance with ASTM
D2922 a~id D3017 (miclear-gauge method) or ASTM D1556 (sandcone method).
The field density test results obtained within the subject pad areas are sununarized
in Table I. Approximate locations of the field density tests are shown on Plates 1
through 3.
Field density tests were taken at vertica] intervals of approximately 1 to 2 feet and
tl~e compacted fills were tested at the tiil~e of placement to detennine moisture
content, in-situ density and relative com}~action. Approximately one in-place
density test was taken for each 1,000 cubic yards of fill placed uld/or for each 2
feet in vertical heigl~t of compacted fill. Tl~e achial number of tests taken per day
varied with flie project coilditioi~s. Wlien field density tesYs indicated a relative
compactioil of less Yhan 90 percent, the approxiil7ate limits of tl~e substandard fill
were establisl~ed. Tl~e substandard area was then eiYher removed or reworked in-
place. Tl~e results of die field densiYy testing included that tlle fills were com}~acted
to 90 percent or more relative compaction.
Visual classification of earth materials in the field was the basis for detennining
which maximum dry density value was applicable for a given density test.
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TR 32169 Pads 1-18/Temecula J.N. 287-04
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Fill Slopes
t Where modified pad areas created fill slopes, the fill slope was founded on a key
excavated 1 to 2 feet into exposed compacted fill. The key widths were
' f 2
t
di
t
k i
t
th
l
il
d
b
f
id
d
opes a
a gra
en
o
ac
n
o
e s
t
te
-
eet w
e ui
a}~proximately 15 to 20
t percent or more. Fill slopes were constnicted at gradients of 2:1
(horizontalvertical [h:v]) or flatter to heights of approximately 8 to 11 feet. Final
' surface compaction on the fill slopes was achieved by track-walking and/or wheel-
l
d
b
b
h
y an
e
ot
gross
rolling the slope surface. The fill slopes are considered to
~ surficially stable to the heights and inclinations at which they were constructed.
Cut Sloues
~
No cut slopes were conshl~cted during the gradiug of Tract 32169.
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LABORATORY TESTING
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Maximum DrV DensitV
' Maximum dry density and optimum moistm-e content for the soils encountered
during ~rading were deternlined in our laboratory in accordance with
~ ASTM D1557. Pertinent test values are summarized in Appendix A.
' Expansion Index Tests
Expansion index tests were perfonned on representative samples of soil existing at
' or uear finish-pad grade wifllin the subject lots. These tests were perfomled in
accordance with ASTM D4829. Test results are summarized in Appendix A.
' Corrosivitv Testing
1 Soluble sulfate analyses were deterniined for representative samples of soil existing
at or near finish grade within the suUject lots. Tl~ese tests were perforn7ed in
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TR 32169 Pads 1-18/Temecula J.N. 287-04
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accordance with Califomia Test Method (CTM) 417. Test results are summarized
'' in Appendix A.
' Water-soluUle chloride concentration, resistivity a~~d pH were detennined for
selected samples in accordance with CTM 422 (chloride) and CTM 643 (resistivity
' and pH). The results of these analyses are sununarized in Appendix A.
' FOUNDATION-DESIGN RECOMMENDATIONS
' Foundation Tvaes
Tl~e use of post-tensioned slab-on-ground foundations may be utilized for the
' proposed residential structures. Foundation-design recommendations were
previously presented by Petra for Tract 32169 (Peh~a, 2004) based on anticipated
, as-graded conditions. Based on Petra's oUservations during rougl~ grading and
laboratory testing, the previous design recommeudations remain applicable and are
' reiterated herein.
~ Allowable Soil-Bearing Capacities
An allowaUle soil-Uearing capacity of 2,000 powids per square foot (ps~ may be
' used for footings founded at a depth of 12 inches or more below the lowest adjacent
final exterior grade. Tl~is value may Ue ivcreased by 250 psf for each additional 6
' inches of depth, to a value of up to 4,000 ps£ Recommended allowable soil-
Uearing values include botl~ dead and live loads and may be increased by one-tl~ird
' when designing for short-duration wind and seismic forces.
' Settlement
~ Based on the general settlement characteristics of tl~e compacted fill soils which
underlie tl~e subject lots, it has Ueen estimated that the total settlement will be
' approximately 1 inch. Differential settlement is expected to Ue about 1 inch over a
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TR 32169 Pads 1-18/Temecula J.N. 287-04
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horizontal distance of approximately 40 feet, equivalent to an a~lgular distortion of
~~ 1:480. It is anticipated that the majority of the settlement will occur during
construction or sl~ortly thereafter as building loads are applied.
~ Lateral Resistance
' An allowable passive earth pressure of 300 psf per £oot of depth to a value of up to
2,000 psf may be used to detenniue lateral-Uearing resistance for building footings.
, If combining total lateral resistuice, the passive pressure or friction resistance
should Ue reduced by 50 percent. The above values may Ue increased Uy one-third
' wheu considering short-duration wind and selsmic forces. A coefficient of friction
of 0.35 times the dead-load forces may also be used bet~ueen concrete and the
~ supportiug soils to detennine lateral-sliding resistance.
' The above values are Uased on footings placed directly against compacCed fill.
Therefore, in the case where footing sides are formed, Uackfill against the footings
,' should Ue compacted to a of 90 percent or more of maximum dry density as
deteiniined Uy ASTM D1557.
' Footin~ Setbacks from Descendin~ Slopes
' Where residential structures are proposed near the tops of descending coinpacted-
' fill slopes, the footiug setbacks fi~oin the slope face sl~ould conform with 1997
' Unifonn Building Code (UBC) Figure 18-I-1. The required setback is H/3 (one-
third the slope height) or more measured along a horizo~ltal line projected fi-om the
' lower outside face of the footing to the slope face. The footing setbacks should be
5 feet or more where the slope height is 15 feet or less and vary up to 40 feet where
' the slope height exceeds 15 feet.
' Wl~ere residential structures are proposed near the tops of descending cut slopes
composed of sound granitic bedrock, as detenniiied Uy the project geotechnical
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consultant, the footing setbacks from the slope face should also generally confonn
, with 1997 UBC Figure 18-I-1; however, the maximum footing setback may be
reduced to 15 feet in lieu of 40 feet where the slope height exceeds 15 feet.
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BuildinE Clearances from Ascendine Slopes
, Building setUacks fi-om ascending cut and fill slopes should confonn witl~ 1997
UBC Figure 1&I-1 that requires a buildnig clearance of H/2 (one-l~alf the slope
' lieight) varying fronz 5 feet miniiinun to 15 feet maximum. The building clearance
is measured along a horizontal line projected from tlre toe of the slope to the face of
' the Uuilding. A retaining wall may be constructed at the Uase of tl~e slope to
achieve the required building clearance.
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Footing Obse--vations
' Building-footing trenches should be oUseived Uy a represeutative of Petra to
document that they have been excavated into competent material and that
' a}~propnate setbacks are inet for foundations adjacent Co graded or natural slopes.
The foundation excavations should be observed prior to the placement of fonns,
' reinforcement or concrete. The excavations should be tnmmed neat, level and
square. Loose, slougl~ed or moisture-softened soil should Ue removed prior to
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i
e.
ng concre
plac
~ Soils derived from footing and utility-treucl~ excavatioils should not be placed in
slab-on-~round areas unless the soils u-e compacted to 90 percent or more of
' maximum dry density as determined Uy ASTM D1557.
' Expansive Soil Considerations
Results of preliminary laboratory tests indicate near-surface soils exhibit a VERY
' LOW to MEDIUM expansion potential as classified in accordance with 1997
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~ UBC Table 18-I-B. This condition is given consideration with the followiilg
II ~ foundations-design recommendations.
I , Post-Tensioned Slabs
The actual design of post-tensioned footings and slaUs is referred to the project
~ structural engineer. To assist the struchiral engineer in design, the following
puameters are recommended.
' • Periineter footings for either one- or two-story dwellings may Ue founded at a
~ depth of 12 inches or more Uelow the nearest adjacent final-ground surface.
Iuterior footings may Ue founded at a depth of 12 inches or more Uelow the top of
the finish-floor s1aU.
' • Dwelling-area floor slabs constructed on-ground should Ue underlain with a
moisture-vapor retarder coilsisting of a 10-mil tl~ick polyethylene membrane.
' One inch or more of clean sand should be placed over the inemUrane to promote
unifonsi curiug of the concrete.
, • Presaturation of subgrade soils Uelow s]aUs-on-ground will not be required.
However, subgrade soils should Ue thoroughly moistened prior to placing
concrete.
' • Soil pa~'ameters are presented in tl~e following table for preliminu-y design
pmposes.
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TR 32169 Pads 1-18/Temecula
January 4, 2005
J.N. 287-04
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~ ~ - ~ .
Expansion Index
~ ~ Very Low
and Low
(0 [0 50) .
Medium
(51 to 90)
Assumed percent clay 30 SO
Clay type Monhnorillonite
Approximate depHi of constaut suction (feet) 7.0 7.0
Approximate soil suction (pF) 3.6 3.6
Approximate velocity or moisture flow
(iilcl~es/month) 0,7 0.7
Thornwaite &dex -20 -20
Average edge moisture Center lift 4.6 5.3
variation distance, e,,,
(feet)
Ed~e lift
2.2
2.5
ated swell
y
Ai~tici Center lifr 1.4 32
,
,,,
p
(inches) Edge lift 0.4 0.8
SEISMIC CONSIDERATIONS
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Ground Motions
The residentia] struchires should be designed and constructed to resist the effects of
seismic ground motions as provided in 1997 UBC Sections 1626 through 1633.
Tlie uiethod of design is dependent ot2 the seismic zoning, site characteristics,
occupancy category, Uuilding configuration, type of structiu~al system uld on the
buildivg hei~ht.
For structural design in accordance with tl~e 1997 UBC, a computer program
developed Uy Thomas F. Blake (UBCSEIS, 1998/1999) was utilized which
compiles fault infonnation for a pa~ticular site using a modified version of a data
file of approximately 150 California faults that were digitized by the Califomia
Division of Mines and Geology and the U.S. Geological Suivey. This prograin
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, WILLIAM LYON HOMES, INC. January 4, 2005
TR 32169 Pads 1-18/Temecula J.N. 287-04
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computes various information for a particular site including the distance of the site
' fi-om each of the faults in the data file, the esYimated slip-rate for each fault and the
"maximum moment magnitude" of each fault. The program selects tUe closest
'' Type A, Type B and Type C faults from tl~e site and coi~~putes the seismic design
coefficients for each of the fault types. The program then selects the largest of the
' coinputed seismic design coefficients and designates these as tl~e design
coefficients for tl~e suUject site.
The Elsinore-Temecula fault, which lies a}~proximately 3.6 kilometers (2.2 miles)
to the southwest of the site, would probably generate severe site ground motions
with an anticipated maximum moment magiitude of 6.8 and an anticipated slip rate
of 5.0 mm/year. The following 1997 UBC seisinic desi~i coefficients should be
used for the proposed stnichires. Tliese criteria are based on tlie soil pirofile type,
as dete~inined by suUsurface geologic conditions, on tl~e proximity of the site to the
Elsinore-Glen ivy fault a~id on the maximum momeut ma~titude and slip rate of
the fault.
1997 UBC TABLE FACTOR
Figm'e 16-2 Seismic Zone 4
16-I Seismic Zmie Factor Z 0.4
16-U Seismic Source Type B
16-J Soil Profile Type So
16-S Near-Source Factor Na 1.1
16-T Near-Source Factor N~ ~ ~4
16-Q Seisinic Coefficient C, 0.55
16-R Seismic Coefficient C„ l.z~
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WILLIAM LYON HOMES, INC.
TR 32169 Pads 1-18/Temecula
Januu-y 4, 2005
J.N. 287-04
Page 12
RETAININGWALL DESIGN RECOMMENDATIONS
Footing Embedments
Tl~e base of retainiug-wall footings consri-ucted on level ground may be founded at
a depth of 12 inches or more below the lowest adjacent final grade. Where
retainin~ walls are ~roposed on or witl~iil 15 feet froin the top of adjacent
descending slopes, the footings should be deepened such that a horizontal cleu-ance
of 15 feet or more is maintained Uetween the outside Uottom edges of the footings
and the face of tl~e slope. Footing excavations should be observed by tl~e project
geoteclniical representative to document tl~at the footing excavations extend into
competent-bearing soils and to the embedments reconunended aUove. These
oUservations should Ue perfonned prior to placing fornls or reinforcing steel.
Active Earth Pressures
An active lateral-earth pressure equivalei~t fluid l~aving a density of 45 pounds per
cubic foot (pc~ sUould tentatively Ue used for design of cautilevered walls retaining
a drained, level backfill comprised of onsite soils of MEDIUM expailsion potential.
Where the wall backfill slopes upward at 2:1 (l~:v), the above value should be
increased to 75 pc£ Where select, non-expansive backfill uiaterials are used, these
values may be reduced to 35 and 52 pcf, respectively. Retaining walls sl~oLild Ue
desi,~ied to resist surcharge loads imposed by other nearby walls or sh~uctures in
addition to the above active earth pressures.
Drainage
Weepholes or open vertical masonry joints should be provided in retaining walls
less than 6 feet in l~eight to reduce the likelil~ood of entrapment of water in the
backfill. Weepholes, if used, should be 3 incl~es or more in diameter and provided
at intervals of 6 feet or less along the wall. Open vertical masonry joints, if used,
should Ue provided at 32-inch or Iess intervals. A continuous gravel fill, 12 inches
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WILLIAM LYON HOMES, INC.
TR 32169 Pads 1-18/Temecula
January 4, 2005
J.N. 287-04
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by 12 incl~es, should be placed behind the weepholes or open masonry joints. The
gravel should Ue wrapped in filter fabric to prevent infilh-ation of fines and
suUsequent clogging of the gravel. Filter faUric may consist of Mirafi 140N or
equivalent.
In lieu of weep]~oles or open joints, a perforlted pipe-and-gravel subdrain may be
used. Perforated pipe should consist of 4-inch or more diameter PVC Schedule 40
or ABS SDR-35, with the perforations laid down. The pipe should be emUedded in
1.5 cubic feet per foot of 0.75- or 1.5-inch open-graded gravel wrapped in filter
fabric. Filter fabric may consist of Mirafi 140N or equivalent.
Retaining walls greater than 6 feet high should be provided with a contimious
Uackdrain for the full height of the wall. This drain could consist of a geosynthetic
drainage composite, sucl~ as Miradrain 6000 or equivalent, or a penneaUle drain
~naterial, placed against the entire backside of the wall. If a pernZeable drain
material is used, the backdrain should be 1 or more feet tluclc Caltrans Class II
pernleable material or open-graded gravel or ciushed stone (described above) may
Ue used as penneaUle drain material. If gravel or crushed stone is used, it should
liave less tl~u1 5 percei~t material passing tl~e No. 200 sieve. The drain sl~ould Ue
separated from the Uackfill with a ~eofabric. The upper 1 foot of the backdrain
should Ue covered witl~ compacted fill. A drainage pipe consisting of 4-inch
diameter perforated pipe (described above) suirounded by 1 cuUic foot per foot of
gravel or cnished rock wrapped in a filter faUric should be provided along the Uack
of the wall. The pipe should be placed with perforations down, sloped at 2 percent
or more and discharge to an appropriate outlet tluough a solid pipe. Tl~e pipe
should outlet away from structures uid slopes.
The Uackfilled sides of retaining walls sl~ould be coated with an approved
waterproofing compound to inhibit migration of moisture tln-ough the walls.
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Temporarv Excavations
' To facilitate retaining-wall construction, the lower 5 feet of temporary slopes may
' be cut vertical and the upper portions exceeding a height of 5 feet should be cut
Uack at a gradient of L• 1(h:v) or flatter for the duration of construction. However,
, temporary slopes should Ue observed by tl~e project geoteclmical consultant for
evidence of potential instability. Dependin~ on Uie results of these observations,
, flatter slopes inay be necessary. Tl~e potential effects of various parameters such as
weather, heavy equipment travel, storage near the tops of the temporary
' excavations and construction scheduling should also Ue considered iu the stability
of temporary slopes. Water should not Ue pemiitted to drain over temporary slopes.
' A Uenn should Ue placed at the top of the slope aud water should drain away from
tl~e slope. Surcharges, due to equipment, spoil piles, ctc., sl~ould vot Ue allowed
' within 10 feet of the top of the slope.
~ ~ Wall Backfill
Retaining-wall backfill sliould Ue placed in 6- to 8-inch loose lifts, watered or air-
I' dried as necessary to achieve near-optimum moisture conditions and compacted in-
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SOIL CORROSIVITY
' The corrosion potential of the onsite materials was evaluated for its effect ot1 steel
t and concrete. The corrosion potential was evaluated using the results of IaUoratory
tests on representative samples of the near-surface soils. LaUoratory testmg was
I' performed to evaluate pH, miuimum electrical resistivity and chloride and soluble
sulfate content.
' The test results for pH of Uie soil tested was 81. Measured electrical resistivity of
' 3,700 olnn-cm indicated that site soils may Ue considered moderately corrosive to
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fen-ous metals. Metal piping should be corrosion-protected or consideration should
Ue given to using plastic piping instead of inetal.
~ Testin~ further indicates a soluble sulfate content of 0.004 to 0.008 percent and
chloride content of 218 ppm. We recommend that Type II cement be used. Special
' provisions for the protection of reinforcing steel from chloride attack are not
required. If desired, a conosion engineer may be consulted to provide additional
' recommendations.
' EXTERIOR CONCRETE FLATWORK
' Thickness and Joint SpacinE
Concrete sidewalks and patio-type slabs should be 4 inches or more thiclc aud
' provided with conshuction or expansion joints every 6 feet or less. Concrete
suUslabs to Ue covered with decorative pavers should also Ue 4 inches or more thick
~ ai~d provided witl~ construction joints or expansion joints every 6 feet or less.
Coucrete driveway s1aUs sl~ould Ue 5 incUes or more thicl: and provided with
' constniction joints or expu~sion joints eve~y 10 feet or less.
' Subarade Preparation
Prior to placing concrete, subgrade soils in concrete-flatwark areas should first be
, pre-watered to achieve a moisture content that is equal to or slightly greater than
optimum moisture content and then compacted in-place to a relative compaction of
' 90 percent or more as detennined by ASTM D1557. The aUove moisture content
should be maintained in the subgrade soils during placement of concrete to promote
, wiifonn curing and reduce tl~e development of shrinkage cracks. A representative
of Petra should observe and document the density and moisture content of the soils
' prior to placing concrete.
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WILLIAM LYON HOMES, INC. January 4, 2005
TR 32169 Pads 1-18/Temecula J.N. 287-04
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UTILITY-TRENCH BACKFILL
Utility-trench backfill should Ue compacted to a relative compaction of 90 percent
or more as deternlined by ASTM D1557. Where onsite soils are utilized as
Uackfill, uzechanical compaction should Ue perfornied. The Uackfill should be
placed in approxiinately 1- to 2-foot thick lifts and then i~iechanically compacted
witl~ a l~ydra-hammer, pneun2atic tampers or similar equipuient tl~at can achieve the
recoinmended relative compaction of 90 percent or more. Density testing, along
with proUing, should Ue perfonned Uy representative of Petra to document proper
compaction
Utility trenches deeper flian 5 feet should be laid back at a ratio of 1:1 (h:v) or
flatter or braced. A trench box may Ue used in lieu of sl~oring. If shoring is
anticipated, Petra should be contacted to provide design parameters. For deep
trenches with sloped walls, Uaclcfill materials should Ue placed in approximately 8-
to 12-inch tl~ick loose lifts and UZen compacted by rollin~ witli a sheepsfoot tamper
or similar equipmeut.
Where utility trencl~es are proposed parallel to building footings (interior and/or
exterior trenches), the Uottom of Uie trench should not Ue located within a 1:1 (h:v)
plane projected downward from the outside Uottom edge of tl~e adjacent footing.
Where this coudition occurs, the adjacent footing should be deepened to a depth
adequate to place tl~e Uottom of the tr-ench outside the aUove-described plane.
POST-GRADING OBSERVATIONS AND TESTING
Petra should be notified at the appropriate times iu order that we may provide the
following observation and testing services during the various phases of post-
gradiug construction.
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WILLIAM LYON HOMES, INC. January 4, 2005
TR 32169 Pads 1-18/Temecula J.N. 287-04
Page 17
• Buildin~ Construction
- Observe footing trenches when first excavated to docmnent adequate depth
and competent soil-Uearing conditions.
- If necessary, re-oUserve footing ri~encl~es if trenches are found to be
excavated to inadequate depth and/or found to contain significant slough,
saturated or compressible soils.
• Exterior Concrete-Flatwork Construction
- Observe and test subgrade soils below concrete-flahvork areas to document
adequate compaction and moisture content.
• Utility-Trencl~ Backfill
- Observe and test placement of utiliry-treiich backfill to docwnent adequate
compaction.
• Re-Gradine
- Observe and test placei~ient of any fill to Ue placed aUove or beyond tUe
grades shown on the a~proved grading plans.
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WILLIAM LYON HOMES, INC. January 4, 2005
TR 32169 Pads 1-18/Temecula J.N. 287-04
Page 18
This opportunity to be of service is sincerely appreciated. If you have questions,
please contactthis office
Respectfully submitted,
PETRA GEOTECHNI(
~pFd fl.
0
G yson R. Wa~',
Principal Engineer
WC/GRW/kec
~ ~do.871 ~
u
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~ EXP. °~ '+~ e *
' r o~ ~aur"'
AttacUments: References
Table I- Field Density Test Results
Plates 1 through 3- Maps with Density Test Locations (in pocket)
A~pendix A- LaUoratory Test Criteria/LaUoratory Test Data
Dish'ibution: (1) Addressee
(4) Willianl Lyon Homes, UZa -Field Office
Attentiov: Mr. Fred Lutka
(2) City of Temecula - Public Works Department
Attention: Mr. Reza Jatnes
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TABLE I
Field Density Test Results
I 1/19/04 1 Pad 10 1101.0 9.8 116.2 92 126.0 1
11/19/04 2 Pad 10 1103.0 9.6 1139 90 126.0 1
1I/19/04 3 Pad I1 1103A 10.0 114.7 91 126.0 1
ll/19/04 4 Pad 10 I105.0 10.5 115.5 92 126.0 1
11/19/04 5 Pad 9 1102.0 10.2 114.9 91 126.0 1
11/19/04 6 Pad 9 1104.0 11.0 116.6 93 126.0 1
11/22/04 7 Pad 11 1107.0 10.5 117.0 93 126.0 1
11/22/04 8 Pad 10 1109.0 10.5 116.2 92 126.0 1
ll/22/04 9 Pad 9 1111.0 11.9 114.7 91 126.0 1
11/22/04 10 Pad 11 1113.0 12.7 1159 92 126.0 1
11/22/04 11 Pad 9 1104.0 11.5 1153 92 126.0 1
11/22/04 12 Pad 8 1106.0 11.7 114.2 91 126.0 1
11/22/04 13 Pad 9 1108.0 12.0 115.0 91 126.0 1
] U24/04 14 Pad 9 1110.0 14A ll2.6 91 123.5 2*
1]/24/04 15 Pad 8 1110.0 139 113.7 92 123.5 2*
1 1/24/04 I6 Pad ] 0 1111 A 12.5 111.9 91 123.5 2*
11/24/04 17 Pad 11 1111.0 13.5 114.7 93 123.5 2
I 1/24/04 18 Pad S 1112.0 12.6 1139 91 123.5 2
11/24/04 19 Pad 10 1113.0 12.2 1122 91 123.5 2
1 1/24/04 20 Pad 11 I 1] 3.0 13.3 112.7 91 123.5 2
i l/24/04 21 Pad 1 1109.0 12.4 113.4 92 123.5 2
ll/24/04 22 Pad 1 1110.0 12.0 ll 4.0 92 123.5 2
1 1/24/04 23 Pad 1 1111.0 10.1 117.9 94 126.0 1
11/24/04 24 Pad 2 ll 12.0 ]0.6 118.2 94 126A 1
I 1/29/04 25 Pad 2 1 ll 3.0 12.4 114.4 93 123.5 2
11/29/04 26 Pad 1 1112.0 12.8 113.5 92 123.5 2
11/29/04 27 Pad 8 1112.0 12.2 1129 91 123.5 2
ll/29/04 28 Pad 2 11L.0 11.8 111.9 9t 123.5 2
11/29/04 29 Pad 2 1114.0 12.5 113.8 92 123.5 2
11/29/04 30 Pad 6 1109.0 13.0 ll 5.6 94 123.5 2
11/29/04 31 Pad 6 I111.0 12.7 ll4.4 93 123.5 2
11/30/04 32 Pad 3 1112A 103 117.7 93 126.0 I
71/30/04 33 Pad 3 1113A ll.0 119.4 95 126.0 1
I1/30/04 34 Pad 3 1114.0 9.4 115.8 92 126.0 1
11/30/04 35 Pad 7 finish grade ll 12.8 12J 114.5 93 123.5 2
11 /30/04 36 Pad 4 finish grade 1115.2 122 113.8 92 123.5 2
12/O1/04 37 Pads 5-6 1113.0 12.4 1133 92 123.5 2*
12/02/04 38 Pad 8 finish grade ll 123 12.1 115.0 93 123.5 2
12/02/04 39 Pad 9 finish grade 11123 11.9 114.2 92 123.5 2
12/02/04 40 Pads 8-9 walk finish grade 1110.5 9.8 1169 93 126.0 1~
PETRA GEOTECHNICAL, INC. TR 32169 - Pads 1-18 JANUARY 2005
J.N. 28 7-04 * Sandcone TABLE T-I 1
TABLEI
Field Density Test Results
l2/02/04 41 Pads 10-11 walk finish grade 1112.2 10.1 115.2 91 126.0 1
12/02/04 42 Pad 1 finishgrade 11123 11J 113.3 92 123.5 2
12/02/04 43 Pad 2 finish grade 1115.0 12.2 114 A 92 123.5 2
12/02/04 44 Pad I6 1091A 10.6 118.9 94 126.0 1
12/02/04 45 Pad 16 1093.0 I1J 119.5 95 126.0 1
12/03/04 46 Pad 18 1095.0 133 111.8 91 123.5 2
] 2/03/04 47 Pad 16 1097.0 12.8 113.6 92 123.5 2
12/03/04 48 Pad 18 1099.0 14.2 114.6 93 123.5 2
12/03/04 49 Pad 16 1100A lOJ 117.1 93 126.0 1
12/03/04 50 Pad 13 1101.0 13J 112A 91 123.5 2
12/06/04 ~1 Pad 14 1101.0 129 113.5 92 123.5 2"
12/06/04 52 Pad 12 1103.0 ]2.0 I11.5 90 123.5 2*
12/O6/04 53 Pad 15 1101.0 ]3.8 114.4 93 123.5 2*
12/07/04 54 Pad 13 1103.0 9.8 113.5 90 126.0 1
12/07/04 55 Pad 16 1101.0 ll.7 117_2 93 126.0 1
12/07/04 56 Pad 12 1104.0 109 115.4 92 L6.0 1
12/07/04 57 Pad 15 1103.0 ] 1.5 116.0 92 126.0 1
12/09/04 58 Pad 18 1099A 12.8 112.7 91 123.5 2
12/09/04 59 Pad 17 1099.0 13.9 111.9 91 123.5 2
1 Z/09/04 GO Pad 17 1101.0 l OJ 1173 93 126A 1
12/10/04 61 Pad 5 finish o ade 1 114.4 12.8 113.2 92 123.5 2
I Z/10/04 62 Pad 6 finish grade 1113.5 122 112.4 91 1235 2
12/10/04 63 Pad 3 finish grade 1ll5.7 10.3 115.6 92 126.0 1
12/10/04 64 Pad 10 finishg rade I l 13.2 11.0 117.4 93 126.0 1
12/10/04 65 Pad I 1 finish grade 1113.9 9.8 ll4.8 91 126.0 1
l2/10/04 66 Pad 12 finish grade 1104.6 12.4 114.0 92 123.5 2
12/13/04 67 Pad 13 finish grade 1103.2 133 1133 92 123.5 2
12/13/04 68 Pad 14 finish grade 1102.7 14.7 114.4 93 123.5 2
12/13/04 69 Pad IS finish grade 1104.1 12.5 112.8 91 123.5 2
I Z/13/04 70 Pad 16 finish grade 11013 12.5 112.5 91 123.5 2
72/13/04 71 Pad 17 finish grade ll00.7 12.0 11 L9 91 123.5 2
12/13/04 72 Pad 78 finish grade 1101.9 11.8 ll2.2 91 123.5 2
12/13/04 73 Pad 8 walk finish grade 1110.5 10.6 ]15.8 92 126.0 ]
12/13/04 74 Pad 11 walk finish grade 1109.0 11.2 ll 6.7 93 126.0 1
1 Z/13/04 75 Pad 12 walk finish grade 1105.0 9.8 1149 91 126.0 1
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PETRA GEOTECHNICAL, INC. TR 32169 - Pads 1-18 JANUARY 2005
' J.N. 287-04 * Sandcone TABLE T-I 2
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APPENDIX A
, Laboratory Test Criteria
' Laboratory Maximum Drv Density
Maximum dry density and optimum moisture content were determined for selected samples of soil in accordance
witU ASTM D1557. Pertinent rest values are given on Plate A-1.
'
Exvansion Index
' Expansion index tests were performed on selected samples of soil in accordance with ASTM D4829. Expansion
potential classificatious were determined Yrom 1997 UBC TaUle 18-I-B on the basis of the expansion index values.
Test results and expansion potentials are presented on Plate A-1.
,
Corrosion Tests
, Chemical analyses were performed on selected samples of onsite soil to determi~e concentrations oY soluble
sulfare a~~d chloride, as well as pH and resistivi[y. These tes[s were perfbnned in accordai~ce with California Test
' Metl~od Nos. 417 (sulfate), 422 (diloride) and 643 (pH and resistivitp). Test results are included on Plate A-I.
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' PETRA GEOTECHNICAL, INC. JANUARY 2005
' J. N. 287-04
LABORATORY MAXIMiJM DRY DENSITY
- ' I
Optimum- Maximum
Sample'No. Soil Type Moisture~_ Dr'y Deasifg' ' I~
_ - . , (%) ° (P~fl :
1 Silty find SAND 9.5 126.0
2 Clayey SILT I 12.0 I 123.5
EXPANSION INDEX TEST DATA
- - "
~- Sample P8i1,No.
-
'
. : ,. , ..:.
~ Representative Pads
> ~~ . ~
~ ~
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~ Expansion~~
~Index
Expansion' ~
~POtentiat
2 1 through 3 0 Very I.ow
(> 4 through 7 0 Very Low
9 8 and 9 0 Very Low
11 10 and I1 0 Very L.ow
12 12 and 13 16 Very Low
16 14 through 16 54 Medium
17 17 and 18 50 Low
CORROSION TESTS
-
Sample Fad No. ` i
' Sulfate°~
Chloride;
pH6
"` Resisti~ity' _
Corrosivity Potential :
,
,
; (yo)._
(PPm)
:
(ohm-cm)
concrete: negligible
I1 0.008 steel:
16 0.004 218 8.1 3,700 ~oncrete: nealigiUle
steeL moderate
~ Q) PER ASTM D1557
(?) PER ASTM D4829
(3) PER 1997 UBC Table 18-I-B
. (4) PER CALIFORNIA TEST METHOD NO. 417
(5) PEA CALIFORNIA TEST METHOD NO. 422
, (G) PER CAL[FORNIA TEST METHOD NO. 643
(7) PER CALIFORNIA TEST METHOD NO. 643
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PETRA GEOTECHNICAL, INC. JANUARY 2005
J. N. 287-04 Plate A-1
~ECEOV~~ I
FEB 1 0 2005 ,
CITY' OF 7EMECULA