701 Rochedale Way Brentwood CA

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REPORT OF

GEOTECHNICAL INVESTIGATION

PROPOSED SINGLE FAMILY RESIDENCE

LOT 21 OF TRACT NO. 14944

701 ROCHEDALE WAY

LOS ANGELES (BRENTWOOD), CALIFORNIA

FOR


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March 24, 2011 11-323-22

Mr. Shawn Antin16134 Leadwell StreetVan Nuys, California 91406

Subject: Report Of Geotechnical InvestigationProposed Single Family ResidenceLot 21 Of Tract No. 14944701 Rochedale WayLos Angeles (Brentwood), California

Dear Mr. Antin:

INTRODUCTION

This report presents the results of a geotechnical investigation for the subject

project. During the course of this investigation, the engineering properties of the

subsurface materials, soil and rock, were evaluated in order to evaluate slope stability

and to provide recommendations for design and construction of temporary excavations


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The attached Appendix I, describes the method of field exploration. Figure Nos.

I-1 through I-3 present summaries of the materials encountered at the location of our

exploratory test holes. Figure No. I-4 presents a key to the log of exploratory test pits.

The attached Appendix II describes the laboratory testing procedures. Figure

Nos. II-1 and II-2 present the results of direct shear and consolidation tests on selected

undisturbed samples.

PROJECT CONSIDERATIONS

It is our understanding that the proposed project will consist of construction of a

single family residence at the subject site. The proposed building is expected to be a

two-story structure, with one level above grade and one level approximately below

street grade. The flooring systems are expected to be in a form of concrete grade

slabs.

As part of the proposed project, a swimming pool may also be constructed. The

proposed swimming pool depth is expected to range from about 3 to 6 feet. The

approximate location of the proposed structures are shown on the enclosed Geologic

Map & Site Plan; Drawing No 1

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Where making excavations close to the property line (within the eastern portion

of the north property line where the magnitude of the cut is higher) temporary shoring

should be used during the course of the site grading work. Such shoring system should

consist of cantilevered soldier piles. Within the areas of low cuts and where adequate

horizontal distance beyond the planned line of excavation is available,

unsupported/open excavation slopes with gradients as recommended in this report can

be used.

Structural loading data was not available during the course of preparation of this

report. For the purpose of this investigation, however, it is assumed that maximum

concentrated loads will be on the order of 60 kips, combined dead plus frequently

applied live loads. The retaining wall footings are expected to have loads of on the

order of 6 kips per lineal foot.

ANTICIPATED SITE GRADING WORK

It is expected that the site grading will involve mainly cutting operations in order

to create the proposed finished grades. A portion of the excavated materials will be

used behind the retaining walls constructed along the top of the descending slope (to

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The lot is bound on the north and south by existing single family residences, on

the east by Rochedale Way and on the west by Hanley Avenue. See the enclosed

Geologic Map & Site Plan; Drawing No. 1 for details.

From the terminus of Rochedale Way, the lot descends on a relatively mild slope

approximately 100 feet in the horizontal direction, to the top of a cut slope that extends

to Hanley Avenue. The cut has vertical heights of 15 to 20 feet and an inclination of

about 1.2:1 (horizontal:vertical). The cut slope exposes coarse-grained sandstone

bedrock.

No sign of instability was noted on the existing cut slope, except for minor

erosion in local areas. No sign of tension cracks were observed along the top of the cut

slope. The slope appeared to be grossly stable.

GEOLOGIC AND SOIL CONDITIONS

The geologic investigation consisted of the excavation, inspection, sampling and

geologic logging of two test pits excavated by jackhammers and one boring by a hollow-

stem auger; a review of published geologic maps; and on-site and near-site geologic

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This bedrock unit has been classified as belonging to the Cretaceous-age Chico

formation by other workers; see Figure No. 2 - Regional Geologic Map by Dibblee

(1991). Bedrock onsite was found to generally be massive to thick bedded, with

east-west trending strikes and southerly dips from 30-40 degrees. These observations

are in general agreement with regional geologic maps of the area.

ENGINEERING-GEOLOGIC CONSIDERATIONS

Groundwater was not observed in the test holes. No seeps or springs were noted

on-site, nor does the site have any surface streams passing through it.

The sandstone material underlying the site is generally a very good foundation

material; however, it can be hard to excavate. Boring 1 was advanced with a

hollow-stem auger drill rig, and was unable to penetrate even the upper layer of rock.

For the basement excavation, heavy-duty equipment may be required.From an engineering-geologic point of view, the proposed new single family

residence and pool project can proceed as planned, provided all new structures are

founded in bedrock to sufficient depth and with proper drainage; surface water runoff on

the site should be controlled; and preventive slope maintenance be regularly performed.

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In accordance with the 2007 California Building code (CBC 2007), the project site

can be classified as a C site. The mapped spectral accelerations of SS=1.729 (short

period) and S1 =0.787 (1-second period) can be used for this project. These parameters

correspond to site Coefficients values of Fa =1.0 and FV =1.3, respectively.

EVALUATION AND RECOMMENDATIONS

GENERAL

Based on the geotechnical engineering data derived during this investigation, it

is believed that the proposed construction may be made as planned. It is our opinion

that when the proposed construction and grading are made, following the

recommendations in this report, the site will be safe for the proposed structures against

the hazard of landslide, settlement, or slippage.

It is anticipated that the planned excavations will be made through minor amount

of native soils and mainly rock. Therefore, rock will be exposed at the finished grades.

The bedrock is expected to provide excellent support for the proposed residence and

the associated retaining walls through conventional spread footings. Near the top of the

d di l d f d ti (f i ti il ) h ld b d f t

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wall (whichever is greater) to a maximum value of 15 feet. For the purpose of this

project, a 5 feet clear horizontal distance would be adequate.

When making high cuts close to the north property line, temporary shoring should

be used. Such shoring system should consist of cantilevered soldier piles. The shoring

piles can then be incorporated into the retaining walls and be part of the permanent

structures. The lower portions of the shoring piles (below the base of the excavation)

can be used to provide vertical support through skin friction. Within the areas of low

cuts and where adequate horizontal distance beyond the planned line of excavation is

available, unsupported/open excavation slopes with gradients as recommended in this

report can be used.

The results of our analysis indicated that the subject lot, with the planned grading

work, will remain grossly stable with respect to deep-seated slope instability (having a

factor of safety of greater than 1.5). See the enclosed engineering calculation sheets.

No significant amount of soil occurs on the existing cut slope. Therefore, surficial

slope instability will not be an issue on this project.

Grade slabs may be cast directly over rock, or properly compacted fill soils.

Where grade slabs span between soil and bedrock the bedrock should be

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Unshored Excavations: It is expected that temporary excavations will be made

during the course of site grading work to create the proposed finished grades. The

excavation will be made through minor amount of native soils and massive sandstone

and/or conglomerate rock.

Based upon the engineering characteristics of the subsurface materials, it is our

opinion that temporary excavation slopes through soil and massive bedrock with no

through-going plane of weakness may be made in accordance with the following table:

-----------------------------------------------------------------------------------------------------------------Maximum Depth of Cut Maximum Slope Ratio

(FT) (Horizontal:Vertical)Soil Rock

0-5 1/2:1 Vertical5-10 3/4:1 Vertical>10 1:1 3/4:1

---------------------------------------------------------------------------------- --------------------------------It is recommended that the Engineering Geologist inspect the cut slopes within

larger scale excavations as soon as five feet of bedrock is exposed in order to confirm

the results of our findings. Modification to our recommendations may be necessary if

variations are noted.

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used. The caissons can be incorporated into the retaining walls and be part of the

permanent structures. The lower portions of the shoring piles (below the base of the

excavation) can be used to provide vertical support through skin friction.

The lateral resistance for cantilevered soldier piles may be assumed to be offered

by available passive pressure below the basement level. An allowable passive pressure

of 600 pounds per square foot per foot of depth may be used below the basement level

for soldier piles having center-to-center spacing of at least 2-1/2 times the pile diameter.

Maximum allowable passive pressure should be limited to 6,000 pounds per square

foot. The maximum center-to-center spacing of the vertical shafts should be maintained

no greater than 10 feet.

For design of temporary support, active pressure on piles may be computed

using an equivalent fluid density of 30 pounds per cubic foot. Uniform surcharge may

be computed using an active pressure coefficient of 0.30 times the uniform load.

When using cantilevered soldier piles for temporary shoring, the point of fixity

(for the purpose of moment calculations), may be assumed to occur at some 12 inches

below the base of the excavation. In order to limit local sloughing, it is recommended

that lagging be used where soil is exposed between the soldier piles All wood

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Prior to placing any fill, the Soil Engineer and Engineering Geologist should

observe the excavation bottoms. The areas to receive fill should be scarified and

compacted in-place to a relative compaction of at least 90 percent at optimum moisture

content.

General guidelines regarding site grading are presented below in an itemized

form which may be included in the earthwork specification. It is recommended that all

fill be placed under engineering observation and in accordance with the following

guidelines:

1. All vegetation should be shaved and removed from the site before sitegrading work is initiated;

2. Subdrain should be installed behind all retaining walls. All subdrainshould be observed and approved by this office before backfilling;

3. The subdrain pipes should be laid at a minimum grade of twopercent for self cleaning.

4. The excavated materials from the site may be reused in the areas of newfill. Wall backfill, however, should consist of granular materials.

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10. Inspection and field density tests should be conducted by the Soil

Engineer during grading work to assure that adequate compaction isattained. Where compaction of less than 90 percent is indicated,additional compactive effort should be made with adjustment of themoisture content or layer thickness, as necessary, until at least 90percent compaction is obtained.

SITE DRAINAGE

Site drainage should be provided to divert roof and surface waters from the

property through non-erodible drainage devices to the street. In no case should the

surface waters be allowed to pond behind the walls or flow over the slope surfaces in an

uncontrolled manner. A minimum surface slope of one and two percent should be

maintained in paved and unpaved areas, respectively.

FOUNDATIONS

It is anticipated that, after the planned excavation is made, rock will be exposed

at the finished grades. The bedrock is expected to provide excellent support for the

proposed residence and the associated retaining walls through conventional spread

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1,100 pounds per square foot for the portion of piles extended deeper than 10 feet into

bedrock. Uplift capacity may be assumed one half of the downward capacity.

The above given allowable maximum bearing and skin friction values are for the

total of dead, plus frequently applied live loads. For short duration transient loading;

wind or seismic forces, the given value may be increased by one third.

For friction pile design, the weight of the shafts can be assumed to be taken by

end-bearing, therefore, need not be added to the structural loads. All piles should be

concreted as soon as they are excavated and, for safety, should not be left open

overnight .

During the course of our field investigation, no caving was experienced in the test

holes. On this basis, caving is expected not to occur within drilled holes. If the

foundations are excavated with hand tools, proper shoring should be implemented for

workmen safety where soil is exposed.

Total and differential settlements of the proposed residence and the associated

retaining walls (with foundations established in rock) are expected to be within tolerable

limits; less than 3/8 and 1/4 of one inch, respectively. The major portion of the

settlements are expected to occur during construction

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GRADE SLABS

Grade slabs may be cast directly over bedrock, or properly compacted fill soils.

Where grade slabs span between soil and bedrock, the bedrock should be

over-excavated by some 12 inches and the excavated materials could be used for the

compacted fill (compacted to at least 90 percent relative compaction at optimum

moisture content). This will create uniform subgrade conditions beneath grade slabs

and reduce the chances of uneven subgrade movements. As an alternative to

over-excavation of the rock, a cold joint can be placed at the daylight between soil and

rock. Due to granular nature, soil expansion will not be an issue at this site. For the

purpose of this project, however, the slabs should be at least 5 inches thick and be

reinforced with # 3 bars placed at every 18 inches on center.

In the areas where moisture sensitive floor covering is used and slab dampness

cannot be tolerated, a vapor-barrier should be used beneath the slabs. This normally

consists of a 6-mil polyethylene film covered with 2 inches of clean sand.

RETAINING WALLS

As part of the site grading ork man retaining alls ill be constr cted S ch

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Uniform surcharge effects may be computed using a coefficient of 0.30 times the

assumed uniform loads.

EXCAVATION

During the course of our field investigation, the rock was excavated with difficulty

using a drill machine and power tools. Therefore, it is anticipated that jack hammer and

possible ripping will be required during the course of site grading (excavation) work.

OBSERVATION DURING CONSTRUCTION

The presented recommendations in this report assume that all structural

foundations (spread footings and piles) will be established in rock. All foundation

excavations should be observed by a representative of this office. It is essential to

assure that all excavations are made at proper dimensions, are established in the

recommended bearing material and are free of loose and disturbed soils.

The project engineering geologist should observe the temporary cut slopes.

Modification to our recommendations may be necessary if significant variations are

t d i th l i f t f th d l i b d k

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S L O P E S T A B I L IT Y F O R S E C T I O N A - A ' /S t a ti c /1 1 - 3 2 3 -2 2 / R O C H E D A L E W A Ye : \ a r a \ r o c h e - 1 . p 1 2u n By : AES/24/20114 : 2 1 P M74 0

# F S S o i lo ilo t a laturated Cohesion Fr ict ionie z . L o a da l u ea 2 . 1 1 D e s c .y p e U n i t W t .n i t Wt.n t e r c e p tn g le Su r face L I00 psfN o .p c f )p c f )psf)d e g )o .bedrock3 0 . 030.0nison isoL200 psfL300 psf72 0

70 0

68 0

4 151

62 0

171

6000 200000 02040608000GSTABL7 v.2 FSmin=2.11Safety Factors Are Calculated By The Simplified Janbu Method


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40000 0204060800020 1SLO PE STA BIL ITY FO R SE CT IO N A -A ' /S ta t ic /11-323 -22/RO CHE DAL E W AY\ a ra \ roche-1 . p l t R un B y : A E S 3 /24 /20 11 0 4 :21 P M


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E:\ara\roche-1.0UT Page 1

*** GSTABL7 * * *** GSTABL7 by Garry H. Gregory, P.E. **** Original Version 1.0, January 1996; Current Version 2.004, June 2003 **(All Rights Reserved-Unauthorized Use Prohibited)*********************************************************************************

SLOPE STABILITY ANALYSIS SYSTEMModified Bishop, Simplified Janbu, or GLE Method of Slices.(Includes Spencer & Morgenstern-Price Type Analysis)Including Pier/Pile, Reinforcement, Soil Nail, Tieback,Nonlinear Undrained Shear Strength, Curved Phi Envelope,Anisotropic Soil, Fiber-Reinforced Soil, Boundary Loads, WaterSurfaces, Pseudo-Static & Newmark Earthquake, and Applied Forces.*********************************************************************************Analysis Run Date:/24/2011Time of Run:4:21PMRun By:E SInputata Filename::\ara\roche-l.inOutputilename::\ara\roche-1.0UTUnit System:nglishPlotted Output Filename: E:\ara\roche-1.PLT PROBLEM DESCRIPTION: SLOPE STABILITY FOR SECTION A-A'/Static/11-32 3-22 /ROCHEDALE WAYBOUNDARY COORDINATES17 Top Boundaries17 Total BoundariesBoundary -Left -Left -Right -Right oil TypeNo. ft) ft) ft) ft) elow Bnd

1 .0 0 34.00 7.00 34.00 2 7.00 34.00 7.00 40.00 3 7.00 40.00 2.00 49.00 4 2.00 49.00 7.00 52.00 5 7.00 52.00 3.00 54.00 6 3.00 54.00 3.01 51.00 7 3.01 51.00 6.00 51.00


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E:\ara\roche-1.OUT Page 2

(2) An input value of 0.02 for Phi will set both Phi andC equal to zero, with no water weight in the tension crack.(3) An input value of 0.03 for Phi will set both Phi andC equal to zero, with water weight in the tension crack.BOUNDARY LOAD(S)3 Load(s) SpecifiedLoad-Left-RightntensityeflectionNo.ft)ft)psf)d e g )13.016.0000.0. 024.0121.0000.0. 0321.0140.0000.0. 0NOTE - Intensity Is Specified As A Uniformly DistributedForce Acting On A Horizontally Projected Surface.A Critical Failure Surface Searching Method, Using A Random

Technique For Generating Sliding Block Surfaces, Has BeenSpecified.400 Trial Surfaces Have Been Generated.2 Boxes Specified For Generation Of Central Block BaseLength Of Line Segments For Active And Passive Portions OfSliding Block Is. 0Box-Left-Left-Right-RighteightNo.ft)f t )f t )ft)f t )15.0030.005.0030.00. 0 020.0052.000.0052.00. 0 0Following Are Displayed The Ten Most Critical Of The TrialFailure Surfaces Evaluated. They AreOrdered - Most Critical First.* * Safety Factors Are Calculated By The Simplified Janbu Method * *Total Number of Trial Surfaces Attempted = 0 0Number of Trial Surfaces With Valid FS = 400Statistical Data On All Valid FS Values:FS Max = .635 S Min = .109 S Ave = .956

Standard Deviation = .678 oefficient of Variation = 7.15 %Failure Surface Specified By 5 Coordinate Points


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55.79257.000Factor of Safety***.120* *Failure Surface Specified 6 Coordinate PointsyPoint-Surf-SurfNo.ft)f t )17.21534.12928.96632.62233.44930.40743.21753.27356.55156.99866.55357.000

Factor of Safety***.153* *Failure Surface Specified By 6 Coordinate PointsPoint -Surf -SurfNo. ft) f t )

1 3.641 34.0002 6.454 31.8253 1.054 29.8664 0.887 52.8495 3.925 56.8206 3.969 57.000

E:\ara\roche-1.0UT Page 3

Factor of Safety***.127* *Failure Surface Specified By 5 Coordinate PointsPoint-Surf-SurfNo.ft)f t )17.66234.39728.86033.35433.48831.46241.42052.92952.94157.000

Factor of Safety


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E:\ara\roche-1.OUT Page 4

Point-Surf-SurfNo.ft)f t )1 13.501 634.0002 14.376 633.3823 18.538 630.6124 22.805 628.0055 82.865 654.9456 83.830 657.000Factor of Safety***.192* *Failure Surface Specified ByCoordinate PointsPoint-Surf-SurfNo.ft)f t )1 14.320 634.0002 14.978 633.5553 19.185 630.8524 23.571 628.4535 72.601 651.1996 75.522 655.2577 76.101 657.000Factor of Safety***.193* ***** END OF GSTABL7 OUTPUT ****


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e : \ a r a \ r o c h e - 2 . p 1 2u n By : AES 3/24/20114 : 2 2 P MS o i lo ilo t a laturated Cohesion Fr ic t ion P i e z . L o a d V a l u eD e s c .y p e U n i t W t .n i t W t .N o .p c f )p c f ) I n t e r c e p t( p s f ) A n g l e( d e g ) S u r f a c eN o . L 1L 21, 3 400 psf600 psf400 psfbed rock30.030.0 A n iso A n iso 0 P e a k ( A )kh Coe f . 0 . 5 0 0 ( g )0.150(g)yao __SITE' 24 .7 -117".7'A ,, I (, 11 I) 7o-A 1 1 1pi[1.1-2 t --- \-)r . _ ,. ..Z. - \1,, , . .

1 \ ''I \\:-JI: . \nil?\,\---- ," I l k by. ,,Il i ' %t 1$--1. 1 ./-.)110,1 .... .


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APPENDIX I

METHOD OF FIELD EXPLORATION

In order to define the subsurface conditions, two test pits and one boring were

excavated on the site. The test pits were excavated using power tools. The boring

was drilled with hollow stem drilling machine. The approximate location of the

exploratory test holes are shown on the enclosed Geologic Map & Site Plan; Drawing

No. 1.

Continuous logs of the subsurface conditions, as encountered in the test pits,were recorded during the field work and are presented on Figure Nos. I-1 through I-4

within this Appendix. These figures also show the number and approximate depths of

each of the recovered soil and rock samples.

With hollo stem drilling relati el ndist rbed samples ere obtained b dri ing

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Date: March 21, 2011Project No: 11-323-22i ure No. I-1E X P L O R A T O R Y T E S T P I T N O . 1PROJECT LOCATION: 701 Rochedale Way, LAROJECT TYPE: New SFRDATE LOGGED: March 4, 2011OGGED BY: R. Crook, CEG 924> -1 -Z /5z CI:u j 0p e

>_-.CCo

I L - -' . . . . IWCI Ce mDla,ILI f ) >.5 w2 0 WCI71. . _1 - _ -F-a LL I,.Cr) sr0"'.0 IL- - /c o oC oo_, 207Wo M AT E RI AL D E S C RI P T IO N ( U S C S )112109

1 1

16 N80E45 Sapprox

ResidualSoil (Qrs)

Sandstone(Kcg)

0' - 1.5': Residual Soil, fine sand (SM), silty, clayey with scatteredpebbles, brown, dense, porous, fine roots.

1.5' - 3.75': sandstone, fine-grained, massive with 10" thickconglomerate bed, orange brown, moderately hard, well-indurated,unfractured, moderately weathered.Approximate 45 degree south dip

Total Depth 3.75 Feet. No groundwater, no caving.Test Pit backfilled to surface level after logging.


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Date: March 21, 2011Project No: 11-323-22ig ure No. 1-2E X P L O R A T O R Y T E S T P I T N O . 2PRO JEC T LOCA TION: 701 Rochedale Way, LAROJECT TYPE: New SFRDATE LOGG ED: March 4, 2011OGG ED BY: R. Crook, CEG 924> -

C15 IT:Lr1=1 2} r z0

; , - - z ,2CI- I'- ` 5 I)}Ix2 0

w-EgHa

reL LIC I-.-cn 0o0 I-- I03

oo "--_1 EoL1 J( 9

M AT E RI AL D E S C RI P T IO N ( U S C S )

105 7 ResidualSoil (Qrs)

Sandstone(Kcg)

0' - 1': R esidual Soil, fine sand (S M), silty, clayey with scatteredpebbles, b rown, slightly to m edium dense, p orous, fine roots.

1' - 5.5': sandstone, fine-grained, with pods of gravel, red-brown,slightly to moderately hard, massive, well-indurated, slightlyfractured, moderately to highly weathered.

Total Depth 5.5 Feet. No groundwater, no caving.Test Pit backfilled to surface level after logging.


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Date: March 21, 2011Project No: 11-323-22i ure No. 1-3E X P L O R A T O R Y B O R I N G N O . 1PROJECT LOCATION: 701 Rochedale Way, LAROJECT TYPE: New SFRDATE LOGGED: March 4, 2011OGGED BY: R. Crook, CEG 924> -1 -& 5z iru j o0 a>. c c0 ,.: _--- m L . L ,121Wmd m ..I-ILCI)}5 cc20 wQF..Ia c ew0_ i_(.0 000LIm 030 I-_1 20L1 10 M AT E RI AL D E S C RI P T IO N ( U S C S )11 4 8 ResidualSoil (Qrs)

Sandstone(Kcg)

0' - 2.5': Residual Soil, fine sand (SM), silty, clayey with scatteredpebbles, brown to dark brown, moist, moderately dense.

2.5' - 5': sandstone, fine-grained, massive, orange brown, hard, well-indurated, unfractured, too hard to sample.

Total Depth 5 Feet. No groundwater, no caving.Boring backfilled to surface level after logging.


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APPENDIX II

LABORATORY TESTING PROCEDURES

MOISTURE DENSITYThe moisture-density information provides a summary of soil consistency for

each stratum and can also provide a correlation between soils found on this site and

other nearby sites. The dry unit weight and field moisture content were determined for

each undisturbed sample, and the results are shown on the log of exploratory borings.

DIRECT SHEAR TESTS

After the samples are pre-soaked overnight under initial confining pressure, a

range of normal stresses are applied vertically, and the shear strengths are

progressively determined under each load in order to determine the internal angle of

friction and the cohesion of the sample. After application of each of the confining

pressures, and before the shearing tests, sufficient amount of time is allowed for any

excess pore pressure to dissipate. During the course of shear test, the sample is

allowed to undergo volume change under a given confining pressure. Under each load,

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7

6

5

4

3

NORMAL STRESS IN KIPS/SQUARE FOOT

RENGTH

IN

KIPS/SQUARE

FOOT


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701 Rochedale Way Brentwood CA

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