Soils Report Geotechnologies Aragon

8/13/2019 Soils Report Geotechnologies Aragon

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April 9, 2013File No. 20489

Aragon Properties, Ltd.1590 Rosecrans Avenue, Suite

Manhattan Beach, California 90

Attention: Fred Shaffer

Subject: Geotechnical Engineering Investigation

Proposed Apartment Complex1185 West Sunset Boulevard, Los Angeles, California

Ladies and Gentlemen:

This letter transmits the Geotechnical Engineering Investigation for the subject sitGeotechnologies, Inc. This report provides geotechnical recommendations for theof the site, including earthwork, seismic design, retaining walls, excavations,

foundation design. Engineering for the proposed project should not begin until ap

geotechnical investigation is granted by the local building official. Significant c

geotechnical recommendations may result due to the building department review pro

The validity of the recommendations presented herein is dependent upon re

geotechnical aspects of the project during construction by this firm. The subsurfadescribed herein have been projected from limited subsurface exploration and labor

The exploration and testing presented in this report should in no way be construed

variations which may occur between the exploration locations or which may result in subsurface conditions.

Should you have any questions please contact this office.

Respectfully submitted,

GEOTECHNOLOGIES, INC.

REINARD T KNUR


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TABLE OF CONTENTS

SECTION

INTRODUCTION .......................................................................................................

PROPOSED DEVELOPMENT...................................................................................SITE CONDITIONS ....................................................................................................

LOCAL GEOLOGY ....................................................................................................

GEOTECHNICAL EXPLORATION ..........................................................................FIELD EXPLORATION .........................................................................................

Geologic Materials ...............................................................................................

Groundwater ........................................................................................................Caving ..................................................................................................................

SEISMIC EVALUATION ...........................................................................................

REGIONAL GEOLOGIC SETTING ......................................................................REGIONAL FAULTING ........................................................................................

SEISMIC HAZARDS AND DESIGN CONSIDERATIONS .................................

Surface Rupture ...................................................................................................

Liquefaction .........................................................................................................Lateral Spreading .................................................................................................

Dynamic Dry Settlement......................................................................................Tsunamis, Seiches and Flooding..........................................................................Landslides and Slope Stability .............................................................................

Temporary and Permanent Cuts...........................................................................

Soil Strength.........................................................................................................Surficial Stability .................................................................................................

Oil Wells ..............................................................................................................

Methane................................................................................................................

CONCLUSIONS AND RECOMMENDATIONS ......................................................SEISMIC DESIGN CONSIDERATIONS ..............................................................

2010 California Building Code Seismic Parameters ...........................................

FILL SOILS .............................................................................................................EXPANSIVE SOILS ...............................................................................................

WATER-SOLUBLE SULFATES ...........................................................................

DEWATERING .......................................................................................................GRADING GUIDELINES ......................................................................................

Site Preparation ....................................................................................................Recommended Overexcavation ...........................................................................Compaction ..........................................................................................................

Acceptable Materials ...........................................................................................

Utility Trench Backfill .........................................................................................

Wet Soils ..............................................................................................................


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TABLE OF CONTENTS

SECTION

Hillside Grading Issues ........................................................................................

FOUNDATION DESIGN ........................................................................................Conventional ........................................................................................................

Miscellaneous Foundations ..................................................................................

Foundation Reinforcement...................................................................................Lateral Design ......................................................................................................

Foundation Settlement .........................................................................................

Foundation Observations .....................................................................................

Building Setback ..................................................................................................FOUNDATION DESIGN - FRICTION PILES ......................................................

Vertical Capacities ...............................................................................................

Lateral Design ......................................................................................................Pile Installation ....................................................................................................

Settlement ............................................................................................................

RETAINING WALL DESIGN ................................................................................Cantilever Retaining Walls ..................................................................................

Restrained Drained Retaining Walls ....................................................................Restrained Undrained Retaining Walls ................................................................

Dynamic (Seismic) Earth Pressure ......................................................................TEMPORARY EXCAVATIONS ...........................................................................

Temporary Dewatering ........................................................................................

Excavation Observations .....................................................................................SHORING DESIGN ................................................................................................

Soldier Piles .........................................................................................................

Lagging ................................................................................................................Tied-Back Anchors ..............................................................................................

Anchor Installation...............................................................................................

Lateral Pressures ..................................................................................................Deflection .............................................................................................................

Monitoring ...........................................................................................................

Shoring Observations ...........................................................................................SLABS ON GRADE................................................................................................

Concrete Slabs-on Grade .....................................................................................Design of Slabs That Receive Moisture-Sensitive Floor Coverings ...................

Concrete Crack Control .......................................................................................Slab Reinforcing ..................................................................................................

PAVEMENTS..........................................................................................................

SITE DRAINAGE ...................................................................................................


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TABLE OF CONTENTS

SECTION

DESIGN REVIEW ..................................................................................................

CONSTRUCTION MONITORING ........................................................................EXCAVATION CHARACTERISTICS ..................................................................

CLOSURE AND LIMITATIONS ...........................................................................

GEOTECHNICAL TESTING .................................................................................Classification and Sampling ................................................................................

Grain Size Distribution ........................................................................................

Moisture and Density Relationships ....................................................................

Direct Shear Testing ............................................................................................Consolidation Testing ..........................................................................................

Expansion Index Testing......................................................................................

Laboratory Compaction Characteristics ..............................................................

ENCLOSURES

ReferencesVicinity Map

Local Geologic Map (Lamar)Local Geologic Map (Dibblee)

Geologic Map (in pocket)Cross Section A-A

Cross Section B-B

Cross Section C-CCross Section D-D

Cross Section E-E

Historically Highest Groundwater Levels MapMethane Zone Risk Map

Plates A-1 through A-9

Plates B-1 through B-4Plate C

Plate D

USGS Probabilistic Seismic Hazard DeaggregationSeismic Coefficient Calculator

GStabl7 Printouts (31 pages)Lpile7 Plus Printouts (24 pages)

Calculation Sheet (22 pages)Boring Logs by Geotechnologies, Inc., Report Dated October 18, 2006 (12 p

Boring Logs by Petra, previous report dated October 7, 2004, (2 pages)


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GEOTECHNICAL ENGINEERING INVESTIGATION

PROPOSED APARTMENT COMPLEX

1185 WEST SUNSET BOULEVARD

LOS ANGELES, CALIFORNIA

INTRODUCTION

This report presents the results of the geotechnical engineering investigation perf

subject site. The purpose of this investigation was to identify the distribution an

properties of the geologic materials underlying the site, and to provide

recommendations for the design of the proposed development.

This investigation included drilling 3 borings and excavating 6 test pits,

representative samples, laboratory testing, engineering analysis, review of available

engineering information and the preparation of this report. The excavation locatio

on the enclosed Geologic Map. The results of the exploration and the laborato

presented in the Appendix of this report.

This firm prepared a Geotechnical Engineering Investigation for another client whi

a different development configuration for the site. The report was dated October

was titled as a preliminary report. The report was not submitted to the City of

Department of Building and Safety for review. Several borings and test pits wehowever, lab testing of the soil samples was not performed and the report was not u

boring locations are indicated on the attached Geologic Map and the excavation log

to this report.


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File No. Page 2

PROPOSED DEVELOPMENT

Information concerning the proposed development was furnished by Fred Shaff

Development, Ltd. The site is proposed to be developed with an apartment compl

stories in height. The structure will have two levels of subterranean parking at the

the south end, the structure will be slight above grade with no subterranean levels.

are estimated to be between 500 and 900 kips. Wall Loads are estimated to be bet

kips per lineal foot. These loads reflect the dead plus live load, of which the

approximately 75 percent. The proposed structure is shown relative site boun

attached Geologic Map.

Excavations for the subterranean parking levels on the north end of the structure wi

as 60 feet, not including foundation excavations. The basement excavations will b

24 feet below Sunset Boulevard at the northern end of the site. At the southern end

to 3 feet of fill will be required to raise the grade to the proposed elevation. Th

uncertified fill at the southern end of the structure that will require removal and r

Up to 10 feet to of compacted fill will be necessary.

A permanent cut is proposed on the east side of the structure that will provide a 15

between the east side of the structure and the toe of the proposed slope. The

inclined as steep as 35 degrees and be up to 65 feet high. The top of the slope wil

foot setback from the western and northern property lines. Appropriate terracdowndrains will be required. Due to surface drainage from offsite properties to the

brow ditch will be required at the top of the slope to intercept the offsite water.

A i fil i d i i l d f h i d ill lik l b l


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Any changes in the design of the project or location of any structure, as outlined i

should be reviewed by this office. The recommendations contained in this report

considered valid until reviewed and modified or reaffirmed, in writing, subseq

review.

SITE CONDITIONS

The site is located on the east side of Sunset Boulevard at 1185 West Sunset Bou

Angeles, California. The site is irregular in shape and approximately 2.66 acres in

is bordered by a westerly-descending slope to the north, at grade single and

residential properties and Everett Street to the east, and West Sunset Boulevard to th

The site is shown relative to nearby topographic features on the attached Vicinity M

Topographic relief across the site is as much as 95 feet. Prior to development, t

westerly descending slope, inclined at a 4 to 1 gradient that was as much as 70 fee

1920s or 1930s, the toe of the slope was cut to provide room for several 1-s

structures. This work resulted in cuts up to 45 feet high and inclined at a 1 to 1 gra

the descent of the ridge on the east side of the site, the overall slope and the cut red

to nearly zero at the south end of the site.

No indications of seeps, spring, or slope instability, such as tension crack in the e

distorted buildings, or surficial and deep seated failure were noted. However on thethe site, where the slope was cut and resulted in daylighted bedding conditions,

sloughing was observed. Some of the slough materials have accumulated against th

existing building.


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An attached lot that forms an eastern appendage the main part of the lot and is a

Everett Street. The lot is currently developed with a 1 story at-grade structure.

The slope is vegetated with annual grasses and a few small trees.

LOCAL GEOLOGY

The site is located in the Elysian Hills located to the northeast of downtown Los A

Elysian Hills are characterized by low, rolling topography. The hills are underlain

age, interlayered siltstone and sandstone of the Puente Formation. Bedding orie

Elysian Hills is very uniform dipping from 20 to 50 degrees to the south and south

1970 and Dibblee, 1989). Two local geology maps, reflecting the work of Lam

Dibblee (1989), are attached.

The bedrock is very planar and has few mapped folds or faults in the area. Acc

geologic map prepared by Lamar (1970), a fault is shown to trend in a northe

direction and bisect the site. Evidence of a fault was not observed during the site

although a rock exposure near Boring B-6 (Geotechnologies, 2006) yields bedd

indicative of an open, local fold. The fault is not shown on the map by Lamar (198

PREVIOUS WORK

Kovacs-Byer and Associates, Report dated June 11, 1986, Preliminary Geolo

Engineering Exploration, Proposed Commercial Structure and Ho

1,2,3,4,7,9,11,13,15,16,17,18,19, 21, and 23, Tract 38559, Sunset Boulevard a

Los Angeles, California.

Th f hi i i i i l d d i f 5 i d d illi 4 b i


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folding was observed in the slope cut. A map identifying the excavation locat

included with the report. Therefore, the borings are not indicated on the attached G

so the borings would have limited value and are therefore not included with this rep

Petra Geotechnical, Inc., Report dated October 7, 2004, Due diligence

Evaluation, Proposed Residential Development, Approximately 2 acre site 1

1247 West Sunset Boulevard, City of Los Angeles, California, Job Number J.N

This investigation included drilling 2 borings near the elevation of Sunset Bou

borings identified alluvial soils and Puente Formation bedrock. No landslides w

during the investigation. The boring locations are shown on the attached Geologic

boring logs are attached to this report.

Geotechnologies, Inc., Report dated October 18, 2006, Preliminary Results of Engineering Investigation, Proposed Residential Development, 1187 Sunset Bo

Angeles, California, File No 19267.

This firm performed an investigation on the subject site that included drilling 6

excavating 6 test pits. The investigation was preliminary in scope and did not di

laboratory testing of the geologic materials. The report was not updated nor was ithe City of Los Angeles Grading Division for review. No landslides or deep sea

was noted during the investigation. The excavation locations are shown on

Geologic Map and the boring logs are also included with this report. The informat

in the report provided additional identification of the bedrock structure and the distr

geologic materials groundwater.

GEOTECHNICAL EXPLORATION

FIELD EXPLORATION


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30 to 40 feet. Samples were taken with an automatic trip hammer using a 140

dropped from a height of 30 inches. The samples were collected in a California-m

spoon sampler lined with 2.5 inch diameter brass rings.

The test pits were excavated using hand labor. The test pits were excavated appr

inches square to a depth of 4 to 6 feet, then deepened to a depths ranging from 8 to

a 5-inch diameter hand auger. Samples were taken using hand tools in a sampler

inch diameter brass rings. Test Pit 1 was used to performing a percolation test.

The exploration locations are shown on the Geologic Map and the geolo

encountered are logged on Plates A-1 through A-9. The location of exploratory ex

determined by measurement from hardscape features shown on the Geologic Map

were determined by interpolation from the elevation contours shown on the map.

and elevation of the exploratory excavations should be considered accurate only

implied by the method used.

Geologic Materials

The geologic materials consist of artificial fill, colluvium, alluvium, and interbed

and sandstone bedrock of the Puente Formation. More detailed descriptions of

materials is presented in the following paragraphs. The distribution of the geologic

be identified on the Geologic Map and Cross Sections A-A through E-E.

Fill

Th fill id ifi d i h b i d i Th fill i f i f


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deepest fill is encountered along Sunset Boulevard and the southern end of the si

(this investigation) encountered an underground storage tank. The tank excavatio

to a depth of 10 feet.

Colluvium

Colluvium consists of silty clay and clayey silt that is dark brown to medium br

moist, and firm. Near the base of the colluvium, gravel-sized fragments of th

siltstone bedrock are included. Colluvium was identified in Test Pit 5 and was 4

The colluvium thins southward from Test Pit 5.

Alluvium

Alluvium consist of sandy silt and silty clay that is dark brown to medium brown i

to wet, and has some gravel-sized siltstone fragments near the base of the deposit.

alluvium was identified in Boring 4 (GT, 2006) at 16 feet. A nearby bor

Geotechnical identified alluvium with a thickness of 12 feet. The alluvium is foundthe southern part of the site.

Bedrock (Puente Formation)

The bedrock consists of well bedded clayey siltstone and sandstone that yellow

brown, and brown in color. The bedrock is also moist and moderately hard an

weathered to slightly weathered. The weathering diminishes with depth. Beddin

consistent dipping from southeast to southwest from 16 to 36 degrees. An indicati

f ld f d h f h l B i 3 ( hi i i i


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Groundwater

Groundwater was encountered in all of the borings drilled along Sunset Boulev

occurred at depth of 9.3 feet to 24 feet. These depths correspond to elevations

402.5, respectively. Groundwater was found at similar elevation in the borings d

firm in 2006.

In general, the ground water surface descends to the south. The ground water leve

proposed basement finish floor elevation on the northern end of the structure. The

is several feet below the finish floor elevation at the southern end.

Based on a review of the California Geological Survey Seismic Hazard Evaluation R

Hollywood 7.5-Minute Quadrangle (CDMG, 2006) indicates the Historic

groundwater level at the site is approximately 20 feet below the ground surface.

nearest groundwater contour is located approximately 1 mile away to the south.

Fluctuations in the level of groundwater may occur due to variations in rainfall, temother factors not evident at the time of the measurements reported herein. Fluctuat

occur across the site. High groundwater levels can result in changed conditions.

Caving

Caving could not be directly observed during exploration due to the continuously

of the hollowstem auger. However, caving is not anticipated in the Puente Formati

the clayey alluvial soils. However, where sandy zones of alluvium occur below the

l l li li h i b d C i d i h


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SEISMIC EVALUATION

REGIONAL GEOLOGIC SETTING

The Los Angeles Basin is located at the northern end of the Peninsular Ranges

Province. The basin is bounded by the east and southeast by the Santa Ana Moun

Joaquin Hills, to the northwest by the Santa Monica Mountains. Over 22 million

Los Angeles basin was a deep marine basin formed by tectonic forces betwe

American and Pacific plates. Since that time, over 5 miles of marine and

sedimentary rock as well as intrusive and extrusive igneous rocks have filled the b

the last 2 million years, defined by the Pleistocene and Holocene epochs, the Los A

and surrounding mountain ranges have been uplifted to form the present day landscof the surrounding mountains has resulted in deposition of unconsolidated sedim

lying areas by rivers such as the Los Angeles River. Areas that have experienced

have been eroded with gullies.

REGIONAL FAULTING

Based on criteria established by the California Division of Mines and Geology (

called California Geologic Survey (CGS), faults may be categorized as active, pote

or inactive. Active faults are those which show evidence of surface displacement w

11,000 years (Holocene-age). Potentially-active faults are those that show evid

recent surface displacement within the last 1.6 million years (Quaternary-age). F

no evidence of surface displacement within the last 1.6 million years are considere

most purposes, with the exception of design of some critical structures.


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nature of these thrust faults, their existence is usually not known until they

earthquake. The risk for surface rupture potential of these buried thrust faults is

low (Leighton, 1990). However, the seismic risk of these buried structures

recurrence and maximum potential magnitude is not well established. Therefore,

for surface rupture on these surface-verging splays at magnitudes higher than 6

precluded.

SEISMIC HAZARDS AND DESIGN CONSIDERATIONS

The primary geologic hazard at the site is moderate to strong ground motion

caused by an earthquake on any of the local or regional faults. The potenearthquake-induced hazards was also evaluated including surface rupture, liquefac

settlement, inundation and landsliding.

Surface Rupture

In 1972, the Alquist-Priolo Special Studies Zones Act (now known as the A

Earthquake Fault Zoning Act) was passed into law. The Act defines active an

active faults utilizing the same aging criteria as that used by California Geolo

(CGS). However, established state policy has been to zone only those faults whic

evidence of movement within the last 11,000 years. It is this recency of fault move

CGS considers as a characteristic for faults that have a relatively high potenti

rupture in the future.

CGS policy is to delineate a boundary from 200 to 500 feet wide on each side of th


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performed that demonstrates that the proposed building site is not threatene

displacement from the fault before development permits may be issued.

Ground rupture is defined as surface displacement which occurs along the surfac

causative fault during an earthquake. Based on research of available literature and

reconnaissance, no known active or potentially active faults underlie the subject site

the subject site is not located within an Alquist-Priolo Earthquake Fault Zone. B

considerations, the potential for surface ground rupture at the subject site is conside

Liquefaction

Liquefaction is a phenomenon in which saturated silty to cohesionless soil

groundwater table are subject to a temporary loss of strength due to the buildup o

pressure during cyclic loading conditions such as those induced by an earthquake.

related effects include loss of bearing strength, amplified ground oscillations, late

and flow failures.

The Seismic Hazards Map of the Los Angeles 7.5 Minute Quadrangle from

California (CDMG, 1999), does not classify the site as part of the potentially Liqu

This determination is based on groundwater depth records, soil type, and distan

capable of producing a substantial earthquake. The proposed structure will be

siltstone and sandstone bedrock. This rock does not liquefy due to its mo

consistency.

Lateral Spreading


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Dynamic Dry Settlement

Seismically-induced settlement or compaction of dry or moist, cohesionless soils ca

related to earthquake ground motion. Such settlements are typically most damag

settlements are differential in nature across the length of structures.

Due to the consistency of the bedrock, the potential for seismic settlement of th

considered remote.

Tsunamis, Seiches and Flooding

Tsunamis are large ocean waves generated by sudden water displacement caused by

earthquake, landslide, or volcanic eruption. Review of the County of Los Angel

Inundation Hazards Map, Leighton (1990), indicates the site does not lie within

tsunami inundation boundaries.

Seiches are oscillations generated in enclosed bodies of water which can be causshaking associated with an earthquake. Review of the County of Los Angel

Inundation Hazards Map, Leighton (1990), indicates the site does not lie wi

inundation boundaries due to a seiche or a breached upgradient reservoir.

Landslides and Slope Stability

No landslides were noted on the available geologic maps the site vicinity (Dibbl

Lamar, 1970). Indications of deep-seated landslides were not noted during th

i i i i i i b h D h if b ddi f 18 40 d


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adversely oriented bedrock creating a potential unstable condition if the cut is made

the bedding dip.

Shallow seated slope raveling was noted at the face of the slope cuts made to the n

sides of the existing structures. Indications such as cracks at the top of the cut, an

toe of the slope were observed. No seeps, springs, or sites of lush vegetation we

indications of surficial creep such as flexural folding in the shallow bedrock o

topography were not noted.

Temporary and Permanent Cuts

The slope is composed of a thin cover of fill and colluvium overlying well bedded

sandstone of the Puente Formation. The fill and colluvium thickness combined is

feet thick in Test Pit 5. The underlying siltstone and sandstone bedrock is mo

The rock dips generally to the south and southeast. No definable weathered zone

in the rock nor was a creep-affected zone noted.

Slope stability calculations were performed to determine the factor of safety of the

on the west-facing slope. Slope stability calculations were performed along Cross

and E-E which are considered the most critical relative to the proposed cut. The

the stability analyses conforms with the Recommended Procedures for Imple

California Division of Mines and Geology Special Publication 117 Guideline for A

Mitigating Landslide Hazards in California (Blake, Hollingsworth, and Stewart

computer program GSTABL7 Version 2.002 by Garry Gregory (2001) was utilize

static and pseudostatic conditions. A discussion of the parameters used in the stabil

d b l


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Soil Strength

The slope is comprised of colluvium, and the Puente Formation bedrock. The s

geologic materials was determined by performing direct shear tests at various norm

of the samples were saturated prior to shearing. The strength of the bedrock a

modeled by reshearing the weakest materials identified in the boring samples.

shears were performed 3 times at three different loads on the same ring s

displacement of each shear tests was 0.25 inches and performed at a rate of 0.02

minute. The strength across bedding was determined using shearing the rock

geologic material properties are presented in the A and B Plates of the report A

should be noted that the bedding dips to the south and southeast, which is favorable

to the proposed slope cut. A summary of the material strengths used in the analys

below.

Summary of Geologic Material Strengths Used in Stability Analysi

GeologicMaterial

Modeled

StrengthCharacteristics

Moist

Unit Weight(pcf)

Saturated

Unit Weight(pcf) Cohesion(psf)

A

InF

(d

Compacted Fill Isotropic 120 125 390

Colluvium Isotropic 106 120 580

Puente Formation-Interbedded Siltstone and

Sandstone, Lightly

weathered

Anisotropic 120 125

530

500

(0 to -18)1

(0 to -5)2

(0

(0

Note: 1 Denotes range of inclination for strength value Cross Section B-B (in degrees)2 Denotes range of inclination for strength value Cross Section E E (in degrees)


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Water

No seepage was encountered in the test pits excavated on the slope. However to c

model the presence of water, a phreatic surface was included that rises from th

proposed excavation.

External Loads

An external static load was applied to the Cross Section E-E to model the l

residence at the top of the slope. For the Pseudostatic analysis, a seismic coefficien

used. The seismic coefficient was calculated using the Probabilistic Seismic Ha

website calculator for a 475 year return period and a shear wave velocity of

magnitude 6.62 earthquake at a distance of 6.9 kilometers with a peak ground acc

returned. These values were used for the Seismic Coefficient calculator using

Rathje procedure (1998). The calculation sheets are attached to this report.

Analysis Parameters

The stability analyses were performed using Bishops simplified method to an

failure surfaces and Janbus method to analyze for foliation plane parallel (block-t

Segment lengths of 10 feet were used for Bishops analyses and 15 feet for Janb

Five thousand searches for the lowest factor of safety were performed for the analys

Results

Th bili l i di d h h i i l i h d i


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Cross Section LPILE File No. Analysis Type Condition Factor of SB-B 0489B1a Bishop (curved) Static 1.65

0489B1b Bishop (curved) Pseudo-static 1.200489B2a Janbu (block) Static 1.660489B2b Janbu (block) Pseudo-Static 1.21

Cross Section LPILE File No. Analysis Type Condition Factor of SE-E 0489E1a Bishop (curved) Static 1.53

0489E1b Bishop (curved) Pseudo-static 1.100489E2a

Janbu (block)

Static 1.53

0489E2b Janbu (block) Pseudo-Static 1.10Commentary on Slope Stability

Cross Section E-E identifies a small terrace that was cut near the top of the slope

was cut to create a flat pad for a small residence. The cut has over steepened the s

to the neighbors property to the east. The stability calculations for Cross Section

that the terrace be left in place as filling the area would require placing compacted

of the cut. It is recommended that the terrace be left in place and a retaining wall b

to support the over steepened slope at the top. The terrace should be regarded

compacted fill cap at least 2 feet thick and be composed of clayey soils. The terrac

drain toward the slope face where surface water should be captured by a V-ditch.

Surficial Stability


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Oil Wells

The site is located approximately 600 feet north of the City of Los Angeles Oil

1970). According to the Oil Well Location Map for the City of Los Angele

(DOGGR, 2001), no oil wells have been drilled on the site.

Methane

The site is within a City of Los Angeles, designated Methane Zone according to

Risk Zone Map by the City of Los Angeles, Department of Public Works, (2003)

methane expert should be retained to identify the presence of methane seepage at th

CONCLUSIONS AND RECOMMENDATIONS

Based upon the exploration, laboratory testing, and research, it is the finding of Geo

Inc. that construction of the proposed apartment structure is considered fea

geotechnical engineering standpoint provided the advice and recommendations preare followed and implemented during construction.

The site is underlain by a thin cover of fill soil over much of the site. Howeve

extend locally to 10 feet at the southern site corner where some underground stor

located. The fill soils are underlain by alluvial soils consisting of silty clay to san

moist and extends to a depth of 18.5 feet. The alluvium is deepest at the southern

site and along Sunset Boulevard. Up to 4 feet of colluvium consisting of silty cla

the undeveloped portion of the slope. Bedrock consisting of well bedded clayey

d f h T i P F i d li h i i d i


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Water was identified in all of the recently drilled borings between depth of 9.3 a

Water was identified in the earlier investigations at depths of 9 and 24 fee

recommendation of this firm that the design of the structure considers groundwater

8 feet below the ground surface as measured at the sidewalk elevation.

The proposed basement excavation will remove all of the fill on the north end of

and will expose the bedrock. The southern half of the structure will expose allu

soils.

The existing fill soils, in addition to the upper two feet of alluvial soils should be

recompacted. The proposed structure may be supported on conventional foundati

rock is exposed and deepened foundations excavated through the fill and all

bedrock is deeper; the footings may extend to 15 feet in depth. As an alter

deepened footings are necessary, cast-in-place drilled friction piles may be used. A

of conventional foundations and friction piles may be used as long as both types are

the bedrock.

If the building is designed and constructed with a cold joint at the transition between

fill/alluvium the building may be supported exclusively on shallow conventional fo

this option is selected, all of the fill soils much be removed and compacted, and the

be underlain by at least 3 feet of newly compacted fill soils.

The finish floor slab may be designed and constructed as a conventional slab whe

above the ground water surface. Where the finish floor is below the groundwate

slab must be designed to accommodate the hydrostatic uplift.


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two level parking garage and another at the location of the deeper alluvium. The p

wells is to identify static water depths and to estimate dewatering quantities.

The slope stability calculations required leaving the terrace in place at the top of t

Cross Section E-E. The terrace should be regarded to include a 2-foot thick layer

impermeable soil to prevent infiltration. The layer should be graded so that water

the face of the slope and is near elevation 486 feet. The over steepened slope on th

the terrace should be supported with a retaining wall or permanent shoring. The t

cut should be set back from the property lines 1/5 of the height of the cut, but no gr

feet from the property line. Clarification of the required setback for the exiting

Cross Section E-E should be obtained from the building official.

The proposed cut will be inclined as steep as 35 degrees. Since the slope exceeds a

of 26 degrees, a modification to the City of Los Angeles Building Code will be nece

V ditches will be required at the top, midheight, and toe of the proposed cu

appropriate downdrains. The slope must be planted with erosion resistant gApproved shrubs will also be necessary.

Foundations for small outlying structures, such as property line walls, which will

to the proposed apartment building, may be supported on conventional foundatio

bedrock or alluvium.


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SEISMIC DESIGN CONSIDERATIONS

2010 California Building Code Seismic Parameters

Based on information derived from the subsurface investigation, the subject site is

Site Class C, which corresponds to a Very Dense Soil or Soft Rock Profile, accor

1613.5.2 of the 2010 California Building Code. This information and the site cooinput into the USGS Ground Motion Parameter Calculator (Version 5.1.0) to

Maximum Considered Earthquake (MCE) Ground Motions for the site. Th

Considered Earthquake Ground motions are equivalent to the 2475-year recurr

ground motions adjusted by a deterministic limit. These values are consistent w

International Building Code requirements.

2010 CALIFORNIA BUILDING CODE SEISMIC PARAMETER

Site Class C

Mapped Spectral Acceleration at Short Periods (SS) 2.223g

Site Coefficient (Fa) 1.0

Maximum Considered Earthquake Spectral Response for Short

Periods (SMS) 2.223g

Five-Percent Damped Design Spectral Response Acceleration atShort Periods (SDS) 1.482g

Mapped Spectral Acceleration at One-Second Period (S1) 1.788g

Site Coefficient (Fv) 1.3

Maximum Considered Earthquake Spectral Response for One-Second Period (SM1) 1.024g

Five-Percent Damped Design Spectral Response Acceleration for


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FILL SOILS

The maximum depth of fill encountered on the site was 6 feet in Boring 2 drill

earlier investigation by this firm. However, it is estimated that fill soil in localiz

reach a depth of 10 feet. This material and any fill generated during demoliti

removed during the excavation for the subterranean level and removed from the

may also be removed and recompacted as controlled fill at the southern end of the s

EXPANSIVE SOILS

The onsite geologic materials are in the moderate to high expansion range. The Expwas found to be 54 for bulk samples for alluvium and 110 for bedrock samples re

percent of the laboratory maximum density. Reinforcing beyond the minimum re

City of Los Angeles Department of Building and Safety is not required.

WATER-SOLUBLE SULFATES

The Portland cement portion of concrete is subject to attack when exposed to

sulfates. Usually the two most common sources of exposure are from soil

environments.

The source of natural sulfate minerals in soils include the sulfates of calcium

sodium, and potassium. When these minerals interact and dissolve in subsurface w

concentration is created, which will react with exposed concrete. Over time sulfa


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The water-soluble sulfate content of the onsite geologic materials was tested by C

417. The water-soluble sulfate content was determined to be less than 0.1% p

weight for the soils tested. Based on American Concrete Institute (ACI) Standar

sulfate exposure is considered to be negligible for geologic materials with less th

Type I cement may be utilized for concrete foundations in contact with the site soils

Concrete strength should be a minimum of 2,500psi.

DEWATERING

According to the Seismic Hazard Zone report for the Hollywood 7.5-Minute

(CDMG, 2006), the historic high groundwater level is approximately 20 feet

However two borings drilled by this firm identified water at a depth of 9 feet belo

surface. A depth of 8 feet below the curb elevation should be considered when

permanent dewatering system or potential hydrostatic and buoyancy pressures.

If a permanent dewatering system is used, an underslab drainage system install

subterranean garage floor slab. Gravel filled trenches approximately two feet deep

15 foot centers leading to a sump pump may be used. Drain lines consisting of 4-in

pipes, perforations down, placed in in the trenches approximately 1 foot wide and 1

below the bottom of the gravel blanket. The pipes would then be covered with g

entire gravel and pipe system within the trenches would be wrapped in filter fabric.

Flow rates for dewatering systems are very difficult to estimate. It is recomm

dewatering test be performed in order to estimate flow rates. A preliminary estima

rate through the bedrock is 10 to 100 gallons per minute Flow rates will initially

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GRADING GUIDELINES

Site Preparation

A thorough search should be made for possible underground utilities and/Any existing or abandoned utilities or structures located within the foo

proposed grading should be removed or relocated as appropriate.

All vegetation, existing fill, and soft or disturbed geologic materials shoulfrom the areas to receive controlled fill. All existing fill materials and

geologic materials resulting from grading operations shall be completely properly recompacted prior to foundation excavation.

Any vegetation or associated root system located within the footprint of structures should be removed during grading.

Subsequent to the indicated removals, the exposed grade shall be scarified six inches, moistened to optimum moisture content, and recompacted in

minimum required comparative density.

The excavated areas shall be observed by the geotechnical engineer pricompacted fill.

Recommended Overexcavation

If the structure will be designed with a structural joint at the transition betwe

supported portion and the fill supported portion, the fill supported portion shall be e

minimum depth of 3 feet below the bottom of all foundations.

Compaction

Th Cit f L A l D t t f B ildi d S f t i i i

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Comparative compaction is defined, for purposes of these guidelines, as the ratio o

density to the maximum density as determined by applicable ASTM testing.

All fill should be mechanically compacted in layers not more than 8 inches thick.

be compacted to at least 90 percent of the maximum laboratory density for the m

The maximum density shall be determined by the laboratory operated by Geotech

using the test method described in the most recent revision of ASTM D 1557.

Field observation and testing shall be performed by a representative of the geotechn

during grading to assist the contractor in obtaining the required degree of compa

proper moisture content. Where compaction is less than required, additional com

shall be made with adjustment of the moisture content, as necessary, until a mipercent compaction is obtained.

Acceptable Materials

The excavated onsite materials are considered satisfactory for reuse in the controlle

as any debris and/or organic matter is removed.

Clayey soils should be selectively used for the 2-foot-thick cap near the top of th

purpose of the cap is to prevent the infiltration of water into the bedrock.

Any imported materials shall be observed and tested by the representative of the

engineer prior to use in fill areas. Imported materials should contain sufficient fin

relatively impermeable and result in a stable subgrade when compacted. Any re

i l h ld i f l i i l i h i i d f l

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Imported materials should be free from chemical or organic substances which co

proposed development. A competent professional should be retained in order to

materials and address environmental issues and organic substances which mig

proposed development.

Utility Trench Backfill

Utility trenches should be backfilled with controlled fill. The utility should be bedd

sands at least one foot over the crown. The remainder of the backfill may b

compacted to 90 percent of the laboratory maximum density. Utility trench back

tested by representatives of this firm in accordance with the most recent revision

1557.

Wet Soils

At the time of exploration the soils which will be excavated from the subterranean

building were well above optimum moisture content. Bedrock from the slop

elevation of Sunset Boulevard were near optimum moisture content. It is anticip

excavated material to be placed as compacted fill, and the materials exposed at t

excavated plane will require significant drying and aeration prior to recomp

recommended that bedrock excavated from the slope cut be selectively stockpiled fo

during backfilling procedures.

Pumping (yielding or vertical deflection) of the high-moisture content soils at the b

excavation may occur during operation of heavy equipment min the areas underlain

( h h h lf) Wh i i d l i i i h

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File No. Page 26

The gravel will help to densify the subgrade as well as function as a stabilization

which heavy equipment may operate. It is not recommended that rubber tire

equipment attempt to operate directly on the pumping subgrade soils prior to placi

Direct operation of rubber tire equipment on the soft subgrade soils will likely resul

disturbance to the soils, which in turn will result in a delay to the construction s

those disturbed soils would then have to be removed and properly recompacted.

should be utilized to place gravel as the subgrade becomes exposed.

Shrinkage

Shrinkage results when a volume of soil removed at one density is compacted

density. A shrinkage factor of 5 percent should be anticipated when exrecompacting the bedrock to an average comparative compaction of 92 percent.

Weather Related Grading Considerations

When rain is forecast all fill that has been spread and awaits compaction shal

compacted prior to stopping work for the day or prior to stopping due to inclem

These fills, once compacted, shall have the surface sloped to drain to an area where

removed.

Temporary drainage devices should be installed to collect and transfer excess wate

in non-erosive drainage devices. Drainage should not be allowed to pond anywhe

and especially not against any foundation or retaining wall. Drainage should not

flow uncontrolled over any descending slope.

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Surface materials previously compacted before the rain shall be scarified, brought

moisture content and recompacted prior to placing additional fill, if considered n

representative of this firm.

Abandoned Seepage Pits

No abandoned seepage pits were encountered during exploration and none are know

the site. However, should such a structure be encountered during grading

permanently abandon seepage pits include complete removal and backfill of the ex

compacted fill, or drilling out the loose materials and backfilling to within a few

with slurry, followed by a compacted fill cap.

If the subsurface structures are to be removed by grading, the entire structu

demolished. The resulting void may be refilled with compacted soil. Concr

generated during the seepage pit removal may be reused in the fill as long as all

less than 6 inches in longest dimension and the debris comprises less than 15 perc

by volume. All grading should comply with the recommendations of this report.

Where the seepage pit structure is to be left in place, the seepage pits should clean

and debris. This may be accomplished by drilling. The pits should be filled with

1/2 sack concrete slurry to within 5 feet of the bottom of the proposed foundation

provide a more uniform foundation condition, the remainder of the void should

controlled fill.

Geotechnical Observations and Testing During Grading

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the design concepts, specifications or recommendations during construction requir

this firm during the course of construction. Any fill which is placed should be obs

and verified if used for engineered purposes. Please advise this office at least twen

prior to any required site visit.

LEED Considerations

The Leadership in Energy and Environmental Design (LEED) Green Building R

encourages adoption of sustainable green building and development practices. Cre

Certification can be assigned for reuse of construction waste and diversion of m

landfills in new construction.

In an effort to provide the design team with a viable option in this regard, dem

could be crushed onsite in order to use it in the ongoing grading operations. The e

ramifications of this option, if any, should be considered by the team.

The demolition debris should be limited to concrete, asphalt and other non-deleteri

All deleterious materials should be removed including, but not limited to, pa

ceramic materials and wood.

For structural fill applications, the materials should be crushed to 2 inches

dimension or smaller. The crushed materials should be thoroughly blended an

onsite soils prior to placement as compacted fill. The amount of crushed materi

exceed 20 percent. The blended and mixed materials should be tested by this o

placement to insure it is suitable for compaction purposes. The blended and mi

h ld b d b G h l i I d i l h i h b

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p ,

File No. Page 29

Hillside Grading Issues

A clay cap fill will be necessary at the top of the slope as shown by Cross Section E

should be at least 2 feet thick and not extended higher than elevation 486. Th

should flow toward the face of the slope so water does not accumulate. A V-

required at the brow of the slope to prevent water from flowing of the slope face.

A minimum compaction of 90 percent out to the finish face of fill slopes will

Compaction on slopes may be achieved by over building the slope and cutting

compacted core or by direct compaction of the slope face with suitable equipm

compaction on the slope faces shall be accomplished by back-rolling the slopes in

four foot increments of elevation gain.

FOUNDATION DESIGN

Conventional

Conventional foundations shall bear in the siltstone and sandstone bedrock. Ho

building is constructed with a structural joint at the transition between rock and f

foundations, the proposed structure may be supported on fill and bedrock. All

foundations for each side of the structure must bear in the same material.

Foundations in Bedrock

Continuous foundations in bedrock may be designed for a bearing capacity of 4,50

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Column foundations may be designed for a bearing capacity of 5,000 pounds per

and should be a minimum of 24 inches in width, 18 inches in depth below the low

grade and 18 inches into the recommended bearing material.

The bearing capacity increase for each additional foot of width is 100 pounds pe

The bearing capacity increase for each additional foot of depth is 400 pounds per

The maximum recommended bearing capacity is 7,000 pounds per square foot.

The bearing capacities indicated above are for the total of dead and frequently appli

and may be increased by one third for short duration loading, which includes the ef

or seismic forces.

Foundations in Compacted Fill

Continuous foundations in compacted fill that extends at least 3 feet below

footings, may be designed for a bearing capacity of 2,500 pounds per square foot,

a minimum of 12 inches in width, 18 inches in depth below the lowest adjacent

inches into the recommended bearing material.

Column foundations may be designed for a bearing capacity of 3,000 pounds per

and should be a minimum of 24 inches in width, 18 inches in depth below the low

grade and 18 inches into the recommended bearing material.

The bearing capacity increase for each additional foot of width is 50 pounds per squ

bearing capacity increase for each additional foot of depth is 250 pounds per squ

i d d b i i i 4 000 d f

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The bearing capacities indicated above are for the total of dead and frequently appli

and may be increased by one third for short duration loading, which includes the ef

or seismic forces.

Miscellaneous Foundations

Conventional foundations for structures such as privacy walls or trash enclosures w

be rigidly connected to the proposed apartment structure may bear in bedrock or

Continuous footings may be designed for a bearing capacity of 1,500 pounds per sq

should be a minimum of 12 inches in width, 18 inches in depth below the lowest a

and 18 inches into the recommended bearing material. No bearing capacity

recommended.

Since the recommended bearing capacity is a net value, the weight of concrete in th

may be taken as 50 pounds per cubic foot and the weight of the soil backfill may

when determining the downward load on the foundations.

Foundation Reinforcement

Due to a high expansion potential for the onsite geologic materials, all foundatio

reinforced with a minimum of four #4 steel bars. Two should be placed near t

foundation, and two should be placed near the bottom.

Lateral Design

R i l l l di b id d b f i i i h b f f d


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Building Setback

A top of slope setback will be required at the top of the cut to the eastern slope.

should e 1/5 of the height of the slope, measure at least 2 feet in width, and need

than 10 feet in width.

The City of Los Angeles Building Code requires that the planned building

horizontally from the retaining wall, located at the toe of the adjacent ascending

required setback corresponds to a horizontal distance equal to one-half of the vert

the slope above the retaining wall, with a minimum distance of three feet and

distance of fifteen feet. This distance is measured from the face of the building to

slope.

FOUNDATION DESIGN - FRICTION PILES

Vertical Capacities

A deepened foundation system consisting of friction piles may be utilized for s

southern half of the proposed structure where the depth to bedrock is too great to be

deepened foundations. The capacities of drilled cast-in-place piles are shown on

Friction Pile Capacity Calculations chart. Capacities based on dead plus

indicated. A one-third increase may be used for transient loading such as wind or s

The capacities presented are based on the strength of the soils. The compressiv

strength of the pile sections should be checked to verify the structural capacity of th


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allow the placement of the steel and concrete. If casing is used, extreme ca

employed so that the pile is not pulled apart as the casing is withdrawn. At no tim

distance between the surface of the concrete and the bottom of the casing be less tha

Piles placed below the water level require the use of a tremie to place the conc

bottom of the hole. A tremie shall consist of a water-tight tube having a diameter o

4 inches and be delivered with a concrete pump. The tube shall be equipped withwill close the discharge end and prevent water from entering the tube while it is b

with concrete. The tremie shall be supported so as to permit free movement of the

over the entire top surface of the work and to permit rapid lowering when necessar

stop the flow of concrete. The discharge end shall be closed at the start of the wo

water entering the tube and shall be entirely sealed at all times, except when the con

placed. The tremie tube shall be kept full of concrete. The flow shall be continu

work is completed and the resulting concrete seal shall be monolithic and homogen

of the tremie tube shall always be kept about five feet below the surface of the

definite steps and safeguards should be taken to insure that the tip of the tremie

raised above the surface of the concrete.

Closely spaced piles should be drilled and filled alternately, with the concrete perm

least overnight before drilling an adjacent hole. Pile excavations should be filled

as soon after drilling and inspection as possible; the shafts should not be left open ov

Settlement

The maximum settlement of pile-supported foundations is not expected to ex

Diff i l l i d b li ibl

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RETAINING WALL DESIGN

The lateral loads on retaining walls will reflect the orientation of bedding expose

The west and south wall excavations will expose neutrally-oriented siltstone and sa

The north wall will expose daylighted bedding, and as a result, the lateral loads w

The east wall will have a surcharge imposed by the ascending slope and as a result

be higher as well.

Cantilever Retaining Walls

Retaining walls supporting a level backslope may be designed utilizing a triangula

of active pressure in accordance the following diagram.

HEIGHT OF

WALL

(feet)EQUIVALENT FLUID PRESSURE (Active)

West Wall (along Sunset

Boulevard), and South Wall

Neutral Bedding

(pounds per cubic foot)East Wall (At Toe of Slope)

Neutral Bedding, and slope

surcharge

(pounds per cubic foot)North Wall (Adve

(pounds per cu

Up to 15 - 41 -

Up to 25 30 50 39

25 to 35 39 58 46

35 to 45 44 65 50

45 to 55 48 - 53

55 to 65 50 - 55For this equivalent fluid pressure to be valid, walls which are to be restrained at the

backfilled prior to the upper connection being made. Additional active pressure sho

for a surcharge condition due to sloping ground, vehicular traffic or adjacent structu

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walls to aid in facilitating drainage. Drainage shall be collected and discharged to

drainage area.

Restrained Drained Retaining Walls

Restrained retaining walls may be designed to resist a triangular pressure distributi

as identified in the table below. Additional earth pressure should be added focondition due to sloping ground, vehicular traffic or adjacent structures.

HEIGHT OF

WALL

(feet)EQUIVALENT FLUID PRESSURE (At Rest)



Neutral Bedding

(pounds per cubic foot)

East Wall

(At Toe of Slope) Neutral

Bedding, and Slope Surcharge

(pounds per cubic foot)North W

Adverse Be

(pounds per cu

Up to 35 - 90 -

Up to 65 69 - 71

H

TRIANGULAR DISTRIBUTION OF AT-REST

(Height of Wall)

EARTH PRESSURE

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In addition to the recommended earth pressure, the upper ten feet of the retaining

to streets, driveways or parking areas should be designed to resist a uniform latera

100 pounds per square foot, acting as a result of an assumed 300 pounds pe

surcharge behind the walls due to normal street traffic. If the traffic is kept back at

from the retaining walls, the traffic surcharge may be neglected.

The lateral earth pressures recommended above for retaining walls assume thatdrainage system will be installed so that external water pressure will not be develop

walls. Also, where necessary, the retaining walls should be designed to acco

surcharge pressures that may be imposed by existing buildings on the adjacent prop

Retaining Wall Drainage

Retaining walls should be provided with a subdrain covered with a minimum of

gravel, and a compacted fill blanket or other seal at the surface. The onsite geolo

are acceptable for use as retaining wall backfill as long as they are compacted to a

90 percent of the maximum density as determined by the most recent revision of AS

Certain types of subdrain pipe are not acceptable to the various municipal a

recommended that prior to purchasing subdrainage pipe, the type and brand is cle

proper municipal agencies. Subdrainage pipes should outlet to an acceptable locatio

Where retaining walls are to be constructed adjacent to property lines there is usual

space for emplacement of a standard pipe and gravel drainage system.

circumstances, the use of a flat drainage produce is acceptable.

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The resulting void should be filled with gravel. A collector is placed within the

directs collected waters through the wall to a sump or standard pipe and g

constructed under the slab. This method should be approved by the retaining wall

to implementation.

Sump Pump Design

The purpose of the recommended retaining wall backdrainage system is to reliev

pressure. Groundwater seepage was encountered during exploration at a depth of

water surface may rise to within 8 feet of the ground surface as measured from t

curb.

Groundwater flows through the siltstone and sandstone bedrock which has a very l

conductivity. Based on this consideration the retaining wall backdrainage s

expected to experience an appreciable flow of water. However, for the purpose

flow of 10 to 100 gallons per minute may be assumed. A test of the flow r

performed prior to final design.

Restrained Undrained Retaining Walls

Restrained retaining walls may be designed to resist a triangular pressure distribut

earth pressure and hydrostatic pressure as indicated in the diagram below. Th

pressure shown in the previous table would be increased by 63 pounds per cubic foo

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In addition to the recommended earth pressure, the upper ten feet of the retaining

to streets, driveways or parking areas should be designed to resist a uniform latera

100 pounds per square foot, acting as a result of an assumed 300 pounds pe

surcharge behind the walls due to normal street traffic. If the traffic is kept back at

from the retaining walls, the traffic surcharge may be neglected.

The lateral earth pressures recommended above for undrained retaining walls

permanent drainage system will not be provided. Where necessary, the retaining w

designed to accommodate any surcharge pressures that may be imposed by existing

the adjacent property.

Dynamic (Seismic) Earth Pressure

H(Height of Wa

62.4 H

Hydrostatic PressureAt-Rest Earth Pressure

EFP

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which support over 12 feet of earth. The proposed walls are less than 12 feet in he

the dynamic earth pressure may be omitted.

The seismic Pressure for walls greater in height than 12 feet is 24 psf and has a trian

This pressure should be added to the active pressure to the walls. The higher of t

active pressure and the seismic pressure or the at-rest pressure without the seis

should be used in design.

Waterproofing

Moisture effecting retaining walls is one of the most common post construction

Poorly applied or omitted waterproofing can lead to efflorescence or standing wa

building. Efflorescence is a process in which a powdery substance is produced on

the concrete by the evaporation of water. The white powder usually consists of

such as gypsum, calcite, or common salt. Efflorescence is common to retaining w

not effect their strength or integrity.

It is recommended that retaining walls be waterproofed. Waterproofing design and

its installation is not the responsibility of the geotechnical engineer. A qualified w

consultant should be retained in order to recommend a product or method which w

protection to below grade walls.

Retaining Wall Backfill

Any required backfill should be mechanically compacted in layers not more than 8

l 90 f h i d i b i bl b h i i

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Proper compaction of the backfill will be necessary to reduce settlement of overlyi

paving. Some settlement of required backfill should be anticipated, and any utilit

therein should be designed to accept differential settlement, particularly at the poin

the structure.

TEMPORARY EXCAVATIONS

Excavations on the order of 65 feet in vertical height will be required for the subter

The excavations are expected to expose fill, alluvium, and siltstone and sandst

Unshored cuts in accordance with the following table will be made.

HEIGHT OF

CUT

(feet)ALOLOWABLE CUT HEIGHT (IN FEET)

Fill soils Alluvium Bedrock-NeutralBedding Bedrock AdveUp to 5 Vertical Vertical Vertical Cut to angle o

5 to 7Cut to 1to 1

InclinationVertical Vertical Cut to angle o

7 to 15 Cut to 1to 1Inclination

Cut to to 1(H to V)

Cut to to 1(H to V)

Cut to angle o

15 to 25Cut to 1to 1

Inclination

Cut to 1to 1

InclinationCut to 1to 1 Inclination

All inclinations recommended above refer to uniform cuts. A uniform sloped

sloped from bottom to top and does not have a vertical component.

Where sloped embankments are utilized, the tops of the slopes should be barricad

vehicles and storage loads near the top of slope within a horizontal distance equal to


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SHORING DESIGN

The following information on the design and installation of the shoring is as comple

at this time. It is suggested that Geotechnologies, Inc. review the final shori

specifications prior to bidding or negotiating with a shoring contractor.

One method of shoring would consist of steel soldier piles, placed in drilled holes a

with concrete. The soldier piles may be designed as cantilevers or laterally br

drilled tied-back anchors or raker braces.

Soldier Piles

Drilled cast-in-place soldier piles should be placed no closer than 2 diameters on

minimum diameter of the piles is 18 inches. Structural concrete should be used f

piles below the excavation; lean-mix concrete may be employed above that l

alternative, lean-mix concrete may be used throughout the pile where the reinforcin

a wideflange section. The slurry must be of sufficient strength to impart the l

pressure developed by the wideflange section to the geologic materials. For design

allowable passive value for the bedrock below the bottom plane of excavation ma

to be 600 pounds per square foot per foot. The allowable passive value for the al

the bottom plane of excavation may be assumed to be 350 pounds per square foot

the full lateral value, provisions should be implemented to assure firm contact

soldier piles and the undisturbed geologic materials.

Groundwater was encountered during exploration at a depth of 9 to 17 feet

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discharge end and prevent water from entering the tube while it is being charged w

The tremie shall be supported so as to permit free movement of the discharge end o

top surface of the work and to permit rapid lowering when necessary to retard or sto

concrete. The discharge end shall be closed at the start of the work to prevent wate

tube and shall be entirely sealed at all times, except when the concrete is being

tremie tube shall be kept full of concrete. The flow shall be continuous unti

completed and the resulting concrete seal shall be monolithic and homogeneous. tremie tube shall always be kept about five feet below the surface of the concrete

steps and safeguards should be taken to insure that the tip of the tremie tube is never

the surface of the concrete.

A special concrete mix should be used for concrete to be placed below water. Th

provide for concrete with a strength p.s.i. of 1,000 over the initial job speci

admixture that reduces the problem of segregation of paste/aggregates and dilution

be included. The slump shall be commensurate to any research report for th

provided that it shall also be the minimum for a reasonable consistency for placing

present.

Casing may be required should caving be experienced in the granular (satura

materials. If casing is used, extreme care should be employed so that the pile is no

as the casing is withdrawn. At no time should the distance between the surface o

and the bottom of the casing be less than 5 feet.

The frictional resistance between the soldier piles and retained geologic material m

resist the vertical component of the anchor load. The coefficient of friction may b

b d if b h l b d l i d i

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age 6

bottom of the footing excavation or 7 feet below the bottom of excavated plane

deeper.

Lagging

Soldier piles and anchors should be designed for the full anticipated pressures. Due

the geologic materials, the pressure on the lagging will be less. It is recommelagging should be designed for the full design pressure but be limited to a max

pounds per square foot. It is recommended that a representative of this firm

installation of lagging to insure uniform support of the excavated embankment.

Tied-Back Anchors

Tied-back anchors may be used to resist lateral loads. Friction anchors are recom

design purposes, it may be assumed that the active wedge adjacent to the shoring is

plane drawn 35 degrees with the vertical through the bottom plane of the excavat

anchors should extend a minimum of 20 feet beyond the potentially active wedge.

Depending on the techniques utilized, and the experience of the contractor pe

installation, it is anticipated that a skin friction of 2,000 pounds per square foot cou

for post-grouted anchors. This value assumes that a grout pressure of 100 psi can

Only the frictional resistance developed beyond the active wedge would be effectiv

lateral loads.

Anchors should be placed at least 6 feet on center to be considered isolated. It is

h l 3 f h i i i l h h h i i i d 200

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g

The total deflection during this test should not exceed 12 inches. The anchor defl

not exceed 0.75 inches during the 24 hour period, measured after the 200 percent

applied. All anchors should be tested to at least 150 percent of design load. The to

during this test should not exceed 12 inches.

The rate of creep under the 150 percent test load should not exceed 0.1 inch over

period in order for the anchor to be approved for the design loading. After a sateach anchor should be locked-off at the design load. This should be verified by r

load in the anchor. The load should be within 10 percent of the design load. Wher

tests are not attained, the anchor diameter and/or length should be increased

anchors installed until satisfactory test results are obtained. The installation and

anchors should be observed by the geotechnical engineer. Minor caving during d

anchors should be anticipated.

Anchor Installation

Tied-back anchors may be installed between 20 and 40 degrees below the horizont

the anchor shafts, particularly within sand deposits, should be anticipated and

provisions should be implemented in order to minimize such caving. The anchor

be filled with concrete by pumping from the tip out, and the concrete should exten

of the anchor to the active wedge. In order to minimize the chances of

recommended that the portion of the anchor shaft within the active wedge be ba

sand before testing the anchor. This portion of the shaft should be filled tightly a

the face of the excavation. The sand backfill should be placed by pumping; the sand

a small amount of cement to facilitate pumping.

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Lateral Pressures

Cantilevered shoring supporting a level backslope may be designed utilizing

distribution of pressure as indicated in the following table:

HEIGHT OFWALL

(feet)

CANTELEVERED SHORING

EQUIVALENT FLUID PRESSURE (Active)West Wall (along Sunset


Neutral Bedding



surcharge


(pounds per cu

Up to 15 - 35 -

Up to 25 28 42 30

25 to 35 30 49 37

35 to 45 35 55 41

45 to 55 39 - 44

55 to 65 41 - 47

A trapezoidal distribution of lateral earth pressure would be appropriate where sh

restrained at the top by bracing or tie backs, with the trapezoidal distribution as

diagram below.

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Restrained shoring supporting a level backslope may be designed utilizing

distribution of pressure as indicated in the following table:

HEIGHT OF

WALL

(feet)

RESTRAINED SHORING

EQUIVALENT FLUID PRESSURE (Active)



Neutral Bedding



surcharge


(pounds per cu

Up to 15 - 22H -

Up to 25 18H 26H 19H

25 to 35 19H 31H 23H

35 to 45 22H 34H 26H

45 to 55 24H - 28H

55 to 65 26H - 29H

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sloped embankment and shoring is utilized, the pressure will be greater and must b

for each combination.

Deflection

It is difficult to accurately predict the amount of deflection of a shored embankme

be realized that some deflection will occur. It is estimated that the deflection co

order of one inch at the top of the shored embankment. If greater deflection

construction, additional bracing may be necessary to minimize settlement of adjac

and utilities in adjacent street and alleys. If desired to reduce the deflection, a

pressure could be used in the shoring design. Where internal bracing is used, the

be tightly wedged to minimize deflection. The proper installation of the raker b

wedging will be critical to the performance of the shoring.

Monitoring

Because of the depth of the excavation, some mean of monitoring the performance o

system is suggested. The monitoring should consist of periodic surveying of th

vertical locations of the tops of all soldier piles and the lateral movement along the

of selected soldier piles. Also, some means of periodically checking the load on sel

will be necessary, where applicable.

Some movement of the shored embankments should be anticipated as a result of

deep excavation. It is recommended that photographs of the existing buildings on

properties be made during construction to record any movements for use in th

di

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Shoring Observations

It is critical that the installation of shoring is observed by a representative of Geo

Inc. Many building officials require that shoring installation should be perfo

continuous observation of a representative of the geotechnical engineer. The obser

that the recommendations of the geotechnical report are implemented and so that

of the recommendations can be made if variations in the geologic material or

conditions warrant. The observations will allow for a report to be prepared on the

shoring for the use of the local building official, where necessary.

SLABS ON GRADE

Concrete Slabs-on Grade

Concrete floor slabs should be a minimum of 5 inches in thickness. Slabs-on-gra

cast over undisturbed natural geologic materials or properly controlled fill ma

geologic materials loosened or over-excavated should be wasted from the sitecompacted to 90 percent of the maximum dry density.

Outdoor concrete flatwork should be a minimum of 4 inches in thickness. Out

flatwork should be cast over undisturbed natural geologic materials or properly c

materials. Any geologic materials loosened or over-excavated should be wasted fr

properly compacted to 90 percent of the maximum dry density.

Design of Slabs That Receive Moisture-Sensitive Floor Coverings

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the general and specific moisture vapor transmission paths and any impact on

construction. The qualified consultant should provide recommendations for potential adverse impacts of moisture vapor transmission on various components of

Where dampness would be objectionable, it is recommended that the floor sla

waterproofed. A qualified waterproofing consultant should be retained in order to

product or method which would provide protection for concrete slabs-on-grade.

All concrete slabs-on-grade should be supported on vapor retarder. The design o

the installation of the vapor retarder should comply with the most recent revision

1643 and ASTM E 1745. Where a vapor retarder is used, a low-slump concrete sh

to minimize possible curling of the slabs. The barrier can be covered with a laye

compactible, granular fill, where it is thought to be beneficial. See ACI 302.2R-

for information on the placement of vapor retarders and the use of a fill layer.

Concrete Crack Control

The recommendations presented in this report are intended to reduce the potential fo

concrete slabs-on-grade due to settlement. However even where these recommen

been implemented, foundations, stucco walls and concrete slabs-on-grade may

cracking due to minor soil movement and/or concrete shrinkage. The occurrenc

cracking may be reduced and/or controlled by limiting the slump of the concrete

concrete placement and curing, and by placement of crack control joints at reasona

in particular, where re-entrant slab corners occur.

F d d l f ki i k l j i i

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practical following concrete placement. Crack control joints should extend a minim

one-fourth the slab thickness. Construction joints should be designed by a structural

Complete removal of the existing fill soils beneath outdoor flatwork such as walk

areas, is not required, however, due to the rigid nature of concrete, some crack

design life and increased maintenance costs should be anticipated. In order to pro

support beneath the flatwork it is recommended that a minimum of 12 inches o

subgrade beneath the flatwork be scarified and recompacted to 90 percent relative c

Slab Reinforcing

Concrete slabs-on-grade should be reinforced with a minimum of #4 steel bar

centers each way.

Outdoor flatwork should be reinforced with a minimum of #3 steel bars on 24-inch

way.

PAVEMENTS

Prior to placing paving, the existing grade should be scarified to a depth of 12 inch

as required to obtain optimum moisture content, and recompacted to 90 percent of

Documents

Soils Report Geotechnologies Aragon