12 January 2017

Vanna Whitney Leddy Maytum Stacy Architects 677 Harrison Street San Francisco, CA 94107 Email: vwhitney@lmsarch.com

Subject: 2012 Berkeley Way Apartments Environmental Noise Study

Salter Project: 16-0569

Dear Vanna:

We have conducted an environmental noise study for the project. The purpose of the study is to determine the noise environment at the proposed site, compare measured data with applicable city and state standards, and provide mitigation measures as necessary to meet those standards. This report summarizes the results.

PROJECT CRITERIA

State Noise Standards

Part 1 of the Supplement to the 2016 California Building Code, effective 1 July 2015, requires that the indoor noise level in residential units of multi-family dwellings not exceed DNL1 45 dB where the exterior noise level is greater than DNL 60 dB.

City of Berkeley General P lan

The City General Plan2 has a requirement of DNL 45 dB, which is consistent with the State Standards.

CALGreen

The CALGreen code addresses acoustical issues in several sections. These sections apply to non-residential buildings, which includes the conference rooms, offices, work stations, community room, multipurpose room, commercial kitchen, and meditation/flex room within the building.

1 DNL (Day-Night Average Sound Level) – A descriptor for a 24-hour A-weighted average noise level. DNL accounts for the

increased acoustical sensitivity of people to noise during the nighttime hours. DNL penalizes sound levels by 10 dB during

the hours from 10 PM to 7 AM. For practical purposes, the DNL and CNEL are usually interchangeable. DNL is sometimes

written as Ldn.

2 Note C of the “Land-Use Compatibility for Community Noise Environments” table under Policy EM-47; “Land Use

Compatibility”; Planning and Development Element

2012 Berkeley Way Apartments Environmental Noise Study 12 January 2017 Page 2

Section 5.507.4.3 Acoustical Control

1. There is a requirement for mitigating exterior noise where sound levels regularly exceed 65 dB. If the exterior noise level regularly exceeds 65 dB, then the building envelope must have wall and roof-ceiling assemblies designed to provide an interior noise environment not exceeding an Leq(h)3 of 50 dB in occupied areas during hours of operation.

We assumed that the hours of operation for the commercial spaces would be from 7 am to 10 pm and used the loudest Leq(h) during that period as the basis of design.

NOISE ENVIRONMENT

The proposed 6-story project is located on Berkeley Way between Shattuck Avenue and Milvia Street. The noise environment at the site is predominantly controlled by vehicular traffic along Berkeley Way, with noise from Shattuck Avenue and University Avenue contributing at the higher floors. Berkeley Fire Station No. 2 is located directly across Berkeley Way from the project site, and the associated noise from the fire station (e.g., sirens, horns) contributes to the noise environment, as well.

To quantify the existing noise environment, we conducted three long-term noise measurements between 23 and 27 September 2016 and one 15-minute spot measurement at the project site (see Figure 1 for the measurement locations and measured noise levels). The long-term monitor was at a height of 12 feet above grade. The spot measurement was at a height of 35 feet above grade.

We calculated the noise levels at the various building facades using measured data. A future traffic analysis was not provided for this project. However, we have added 1 dB to the data in our calculations to account for future traffic increases.4

RECOMMENDATIONS

Interior Noise

We calculated the window and exterior door STC5 ratings needed to meet the criteria using the progress drawings received 5 January 2017 that show the floor plans and glazing. Our calculations include the following assumptions:

• Bedrooms, dorms, shelters, work spaces, and offices will have carpet • All other rooms will have hard-surfaced flooring • Ceilings are 9-feet high

3 Leq(h) – The equivalent steady-state A-weighted sound level that, in an hour, would contain the same acoustic energy as

the time-varying sound level during the same hour.

4 The California Department of Transportation assumes a traffic volume increase of three-percent per year, which

corresponds to a 1 dB increase in DNL over a ten-year period.

5 STC (Sound Transmission Class) – A single-number rating defined in ASTM E90 that quantifies the airborne sound insulating

performance of a partition under laboratory conditions. Increasing STC ratings correspond to improved airborne sound

insulation.

2012 Berkeley Way Apartments Environmental Noise Study 12 January 2017 Page 3

• Window sizes and locations are as shown on the floor plans and elevations • The exterior facade will be HardiePanel, Lap Siding, or a premium fiber cement board panel

The recommended STC ratings are for full window assemblies (glass and frame) rather than just the glass itself. Tested, sound-rated assemblies should be used.

For reference, typical one-inch glazing assemblies (two 1/4-inch thick panes with a 1/2-inch airspace) can achieve an STC rating of 28 depending on the window type and manufacturer.

To meet the indoor DNL 45 dB criterion, it will be necessary for all of the windows in the facades to be sound-rated. The window and exterior door STC ratings will need to be as shown on Figures 2 through 6.

Where windows need to be closed to achieve an indoor DNL of 45 dB, an alternative method of supplying fresh air (e.g., mechanical ventilation) should be considered. This applies to the entire project and should be discussed with the project mechanical engineer.

Commercial

To meet the CALGreen interior noise criterion of Leq(h) 50 dB, the glazing system STC ratings for the commercial space will need to be as shown on Figures 2, 3 and 6.

* * *

This concludes our environmental noise study for the 2012 Berkeley Way project. Should you have any questions, please give us a call.

Sincerely,

CHARLES M. SALTER ASSOCIATES, INC.

Blake Wells, LEED® Green Associate Jason R. Duty, PE Consultant Vice President Enclosures as noted

Tree Assessment Map 2012 Berkeley Way Berkeley, CA Prepared for: Bridge Housing Corporation San Francisco, CA February 2017 No Scale Notes Base map provided by: Sandis Oakland, CA Numbered tree locations are approximate.

325 Ray Street Pleasanton, California 94566 Phone 925.484.0211 Fax 925.484.0596

94 95 96 97 98

99

100 101 102 103

TREE SPECIES SIZE CONDITION SUITABILITY COMMENTSNo. DIAMETER 1=POOR FOR

(in inches) 5=EXCELLENT PRESERVATION

94 Coast live oak 8,6,5 2 Low Poor form and structure; stem removed E.; one sided W.; twig dieback.

95 Coast live oak 12,9,9 2 Low Multiple attachments at 4'; seam in attachments; moderate dieback; cracked curb S.

96 Coast live oak 10 3 Low Multiple attachments at 6'; sweeps W. from base; basal wounds; twig dieback.

97 Coast live oak 17 3 Moderate Multiple attachments at 5'; good form; twig dieback; displacing sidewalk 2"; almost outgrown 3' planter strip.

98 Coast live oak 12 3 Low Multiple attachments at 8'; fair form and structure; basal wound/grown over & cracked curb S.

99 Coast redwood 36 2 Low Topped at 60' with crooks in trunk above; extensive dieback w/ dead branches to 3"; engulfed in vines.

100 Coast live oak 10,9,5,4 2 Low Off-site, no tag; multiple attachments at 2'; growing through/embedded chain link dance; in very narrow planting strip.

101 Coast live oak 8,7,7,6 2 Low Off-site, no tag; codominant trunks at base; growing through/embedded chain link fence; in very narrow planting strip.

102 Coast live oak 17 3 Moderate Off-site, no tag; codominant trunks at 10'; grown around/embedded pipe at 1'; in small planter.

103 Buckeye 13,11,9,8,4 4 Moderate Off-site, no tag; multiple attachments at 3'; growing against retaining wall; in very narrow planting strip.

Tree Assessment Berkeley WayBerkeley CaliforniaFebruary 2017

Page 1

Prepared for BRIDGE Housing Corporation

GEOTECHNICAL INVESTIGATION PROPOSED MIXED-USE BUILDING

2012 BERKELEY WAY Berkeley, California

UNAUTHORIZED USE OR COPYING OF THIS DOCUMENT IS STRICTLY PROHIBITED BY ANYONE OTHER THAN THE CLIENT FOR THE SPECIFIC PROJECT

March 27, 2017 Project No. 16-1193

March 27, 2017 Project No. 16-1193

Mr. Jamie Hiteshew BRIDGE Housing Corporation 600 California Street, Suite 900 San Francisco, CA 94108

Subject: Geotechnical Investigation Report Proposed Mixed-Use Building 2012 Berkeley Way Berkeley, California

Dear Mr. Hiteshew:

We are pleased to present the results of our geotechnical investigation for the proposed mixed-use building to be constructed at 2012 Berkeley Way in Berkeley, California. Our services were provided in accordance with our proposal dated September 8, 2016.

The project site is located on the south side of Berkeley Way between Shattuck Avenue and Milvia Street, approximately 200 feet west of its intersection with Shattuck Avenue. The project site consists of a rectangular-shaped parcel with plan dimensions of approximately 110 by 320 feet. The site is currently an asphalt-paved parking lot that is owned by the City of Berkeley.

BRIDGE Housing (BRIDGE) in partnership with Berkeley Food and Housing Project (BFHP) plans to construct a mixed-use building at the site. The proposed building will consist of five stories of wood-framed construction (Type III construction) over two levels of reinforced concrete podium (Type 1 construction). The lower podium level will be below-grade and will consist of replacement public parking; park lifts may be installed at the below-grade parking level to achieve a greater number of parking spaces. Above the garage, the BRIDGE and BFHP spaces will be separated by a demising wall and will have separate vertical circulation systems (i.e. exit stairs and elevators) on each side of the demising wall. On the BRIDGE side, there will be 94 units of affordable residential rental housing for families, as well as shared community amenities such as community rooms. On the BFHP side, there will be emergency homeless shelter rooms, transitional housing rooms, studios for permanently supportive housing, supportive services, administrative offices, reception area, conference rooms, computer rooms, community and multipurpose space, commercial kitchen, storage, laundry, and flexible spaces.

From a geotechnical standpoint, we conclude the site can be developed as planned, provided the recommendations presented in our report are incorporated into the project plans and specifications and implemented during construction. The primary geotechnical

Mr. Jamie Hiteshew BRIDGE Housing Corporation March 27, 2016 Page 2 concerns at the site are: 1) a design groundwater level that is near the proposed finished floor of the below-grade level, 2) providing adequate foundation support, and 3) providing lateral support for the proposed excavation while minimizing the impact on the surrounding improvements. We conclude the proposed building may be supported on spread footings or a mat foundation. Where basement slab will extend below the design groundwater level, a under slab drainage system should be installed to reduce hydrostatic pressures. Alternatively, the floor slab/mat should be waterproofed and the foundations be designed to resist hydrostatic pressures.

Our report contains specific recommendations regarding earthwork and grading, foundation design, shoring, and other geotechnical issues. The recommendations contained in our report are based on limited subsurface exploration. Consequently, variations between expected and actual soil conditions may be found in localized areas during construction. Therefore, we should be engaged to observe foundation installation, grading, shoring installation, and fill placement, during which time we may make changes in our recommendations, if deemed necessary.

We appreciate the opportunity to provide our services to you on this project. If you have any questions, please call.

Sincerely yours, ROCKRIDGE GEOTECHNICAL, INC.

Darcie Maffioli, P.E. Linda H. J. Liang, P.E., G.E. Project Engineer Associate Engineer

Enclosure

QUALITY CONTROL REVIEWER:

Craig S. Shields, P.E., G.E. Principal Engineer

TABLE OF CONTENTS

1.0  INTRODUCTION ...............................................................................................................1 

2.0  SCOPE OF SERVICES .......................................................................................................2 

3.0  FIELD INVESTIGATION AND LABORATORY TESTING ...........................................3 3.1  Test Borings .............................................................................................................3 3.2   Laboratory Testing ...................................................................................................4 

4.0  SITE AND SUBSURFACE CONDITIONS .......................................................................5 4.1  Site Conditions .........................................................................................................5 4.2  Subsurface Conditions .............................................................................................6 4.3  Groundwater ............................................................................................................7 

5.0  SEISMIC CONSIDERATION ............................................................................................8 5.1  Regional Seismicity and Faulting ............................................................................8 5.2  Geologic Hazards ...................................................................................................12 

5.2.1  Ground Shaking .........................................................................................12 5.2.2  Liquefaction and Associated Hazards ........................................................12 5.2.3  Cyclic Densification ...................................................................................13 5.2.4  Fault Rupture .............................................................................................13 

6.0  DISCUSSIONS AND CONCLUSIONS ...........................................................................14 6.1  BART Subway Zone-of-Influence .........................................................................14 6.2  Design Groundwater Level ....................................................................................15 6.3  Foundations and Settlement ...................................................................................15 6.4  Underpinning .........................................................................................................16 6.5  Temporary Cut Slope and Shoring ........................................................................17 6.6  Excavation Dewatering ..........................................................................................19 6.7  Excavation, Monitoring, and Construction Considerations ...................................19 6.8  Soil Corrosivity ......................................................................................................20 

7.0  RECOMMENDATIONS ...................................................................................................21 7.1  Site Preparation and Grading .................................................................................21 

7.1.1  Soil Subgrade Preparation..........................................................................21 7.1.2  Soil Subgrade Stabilization ........................................................................22 7.1.3  Fill Materials and Compaction Criteria .....................................................24 7.1.4  Utility Trench Backfill ...............................................................................25 7.1.5  Exterior Flatwork Subgrade Preparation ...................................................26 

7.2  Foundations ............................................................................................................26 7.2.1  Spread Footings .........................................................................................26 7.2.2  Mat Foundation ..........................................................................................27 

7.3  Underslab Drainage System ...................................................................................28 

7.4  Slab-on-Grade Floor ..............................................................................................29 7.5  Permanent Below-Grade Walls ..............................................................................31 7.6  Underpinning .........................................................................................................32 7.7  Temporary Cut Slopes and Shoring .......................................................................33 

7.7.1  Cantilevered Soldier Pile and Lagging Shoring .........................................34 7.7.2  Soldier Pile and Lagging Shoring System with Tiebacks ..........................35 7.7.3  Soil-Nail Shoring System ..........................................................................38 

7.8  Seismic Design.......................................................................................................40 

8.0  GEOTECHNICAL SERVICES DURING CONSTRUCTION ........................................40 

9.0  LIMITATIONS ..................................................................................................................41  REFERENCES

FIGURES

APPENDIX A – Logs of Borings

APPENDIX B – Laboratory Test Results

LIST OF FIGURES

Figure 1 Site Location Map

Figure 2 Site Plan

Figure 3 Generalized Cross Section A-A’ Zone of Influence for BART Subway Structures

Figure 4 Regional Fault Map

Figure 5 Regional Geologic Map

Figure 6 Seismic Hazards Zone Map

Figure 7 Design Parameters for Soldier-Pile-and-Lagging Temporary Shoring System

APPENDIX A

Figures A-1 Logs of Borings B-1 through and A-5 and B-5

Figure A-6 Classification Chart

APPENDIX B

Figure B-1 Plasticity Chart

Figure B-2 Particle Size Distribution

Figures B-3 Unconsolidated-Undrained Triaxial Compression and B-4 Test Reports

Corrosivity Analysis Results

16-1193 1 March 27, 2017

GEOTECHNICAL INVESTIGATION PROPOSED MIXED-USE BUILDING

2012 BERKLEY WAY Berkeley, California

1.0 INTRODUCTION

This report presents the results of the geotechnical investigation performed by Rockridge

Geotechnical, Inc. for the proposed mixed-use building to be constructed at 2012 Berkeley Way

in Berkeley, California. The project site is located on the southern side of Berkeley Way

between Shattuck Avenue and Milvia Street, approximately 200 feet west of its intersection with

Shattuck Avenue, as shown on the Site Location Map, Figure 1.

The project site consists of a rectangular-shaped parcel with plan dimensions of approximately

110 by 320 feet as shown on the Site Plan, Figure 2. The site is currently an asphalt-paved

parking lot that is owned by the City of Berkeley. Existing site grades slope down gently to the

southwest from about Elevation 196 feet1 at the northeastern corner to Elevation 192 feet at the

southwestern corner. The site is bordered by Berkeley Way to the north, single-story

commercial buildings to the east, one- to three-story commercial buildings to the south, and two-

story residential buildings to the west.

BRIDGE Housing (BRIDGE) in partnership with Berkeley Food and Housing Project (BFHP)

plans to construct a mixed-use building at the site. The proposed building will consist of five

stories of wood-framed construction (Type III construction) over two levels of reinforced

concrete podium (Type 1 construction). The lower podium level will be below-grade and will

consist of replacement public parking; park lifts may be installed at the below-grade parking

level to achieve a greater number of parking spaces. Above the garage, the BRIDGE and BFHP

spaces will be separated by a demising wall and will have separate vertical circulation systems

(i.e. exit stairs and elevators) on each side of the demising wall. On the BRIDGE side, there will

be 94 units of affordable residential rental housing for families, as well as shared community

1 Unless otherwise noted, elevations in this report are based on topographic information shown on the

drawing titled “Topographic Survey,” prepared by Sandis, revised January 26, 2017, City of Berkeley Datum.

16-1193 2 March 27, 2017

amenities such as community rooms. On the BFHP side, there will be emergency homeless

shelter rooms, transitional housing rooms, studios for permanently supportive housing,

supportive services, administrative offices, reception area, conference rooms, computer rooms,

community and multipurpose space, commercial kitchen, storage, laundry, and flexible spaces.

2.0 SCOPE OF SERVICES

Our geotechnical investigation was performed in accordance with our proposal dated

September 8, 2016. Our scope of services consisted of evaluating subsurface conditions at the

site by drilling five test borings, performing laboratory testing on selected soil samples collected

from the borings, and performing engineering analyses to develop conclusions and

recommendations regarding:

subsurface conditions

site seismicity and seismic hazards, including the potential for liquefaction and lateral spreading, and total and differential settlement resulting from liquefaction and/or cyclic densification

BART subway zone-of-influence

the most appropriate foundation type(s) for the proposed building

design criteria for the recommended foundation type(s), including vertical and lateral capacities for each of the foundation type(s)

estimates of foundation settlement

lateral earth pressures for basement walls

temporary shoring

underpinning

temporary and permanent dewatering

site preparation and grading, including criteria for fill quality and compaction

slab-on-grade floors

2016 California Building Code site class and design spectral response acceleration parameters

corrosivity of the near-surface soil and the potential effects on buried concrete and metal structures and foundations

16-1193 3 March 27, 2017

construction considerations

3.0 FIELD INVESTIGATION AND LABORATORY TESTING

Subsurface conditions at the site were investigated by drilling five borings and performing

laboratory testing on selected soil samples. Prior to our field investigation, we obtained a

drilling permit from the City of Berkeley, Planning and Development Department, Toxic

Management Division (CBTMD), and contacted Underground Service Alert (USA) to notify

them of our work, as required by law. We also retained a private utility locator, Precision

Locating, LLC, to check that boring locations were clear of underground utilities. Details of the

field investigation and laboratory testing are described in the remainder of this section.

3.1 Test Borings

Five borings were drilled on September 29 and 30, 2016 by Exploration Geoservices, Inc. of San

Jose, California at the approximate locations shown on Figure 2. The borings, designated B-1

through B-5, were drilled to depths between 39 and 50 feet below the existing ground surface

(bgs) using a Mobile B-53 drill rig equipped with hollow-stem augers. During drilling, our field

engineer logged the soil encountered and obtained samples for visual classification and

laboratory testing. The boring logs were developed based on soil conditions observed and

logged by our field engineer during drilling, review of soil samples in the office to confirm

classification, and the results of laboratory tests on selected soil samples. Logs of the borings are

presented in Appendix A on Figures A-1 through A-5. The soil encountered in the borings was

classified in accordance with the classification chart shown on Figure A-6.

Soil samples were obtained using the following samplers:

Sprague and Henwood (S&H) split-barrel sampler with a 3.0-inch outside diameter and 2.5-inch inside diameter, lined with 2.43-inch inside diameter stainless steel tubes

Standard Penetration Test (SPT) split-barrel sampler with a 2.0-inch outside and 1.5-inch inside diameter, without liners.

16-1193 4 March 27, 2017

The type of sampler used was selected based on soil type and the desired sample quality for

laboratory testing. In general, the S&H sampler was used to obtain samples in medium stiff to

very stiff cohesive soil and the SPT sampler was used to evaluate the relative density of sandy

soil.

The samplers were driven with a 140-pound, downhole safety hammer falling about 30 inches

per drop. The samplers were driven up to 18 inches and the hammer blows required to drive the

samplers were recorded every six inches and are presented on the boring logs. A “blow count” is

defined as the number of hammer blows per six inches of penetration or 50 blows for six inches

or less of penetration. The blow counts used for this conversion were: (1) the last two blow

counts if the sampler was driven more than 12 inches, or (2) the only blow count if the sampler

was driven six inches or less. The blow counts required to drive the S&H and SPT samplers

were converted to approximate SPT N-values using factors of 0.7 and 1.2, respectively, to

account for sampler type and approximate hammer energy, as well as the fact that the SPT

sampler was used without liners, but could accommodate liners. The converted SPT N-values

are presented on the boring logs.

Upon completion of drilling, the boreholes were backfilled with cement grout under the

observation of the CBTMD grout inspector and topped with concrete. The soil cuttings

generated by the borings were collected in drums. The soil drums were removed from the site at

the completion of drilling and subsequently disposed of in a non-hazardous waste disposal

facility.

3.2 Laboratory Testing

We re-examined each soil sample obtained from our borings to confirm the field classifications

and selected representative samples for laboratory testing. Geotechnical laboratory tests were

performed on selected soil samples to assess their engineering properties and physical

characteristics. Soil samples were tested by B. Hillebrandt Soils Testing, Inc. of Alamo,

California to measure moisture content, dry density, percent passing the No. 200 sieve, plasticity

(Atterberg limits), and strength. Corrosivity testing of two samples of near-surface soil was

16-1193 5 March 27, 2017

performed by Sunland Analytical of Rancho Cordova, California. The results of the

geotechnical laboratory tests are presented on the boring logs and in Appendix B.

4.0 SITE AND SUBSURFACE CONDITIONS

This section summarizes the site and subsurface conditions at 2012 Berkeley Way based on the

results of this investigation, published geologic data, and subsurface information collected from

other projects in the vicinity. Site-specific descriptions of the site, subsurface soil, and

groundwater conditions are presented below.

4.1 Site Conditions

The site is currently occupied by an asphalt-paved parking lot owned by the City of Berkeley.

Existing site grades slope down gently to the southwest from about Elevation 196 feet2 at the

northeastern corner to Elevation 192 feet at the southwestern corner.

Three single-story commercial buildings are located to the east of the site. The single-story

structure abutting the northeastern corner of the site is at a similar elevation as the parking lot.

The other single-story structures to the east are founded at a gradually lower elevation toward the

intersection of Shattuck and University avenues.

There is a retaining wall along the southern property line and the top of wall is at the current site

(parking lot) grade. The site is bordered by five one- to three-story commercial buildings to the

south, as shown on Figure 2. There are three pedestrian entrances to some of the commercial

building from the City of Berkeley parking lot. Topographic Survey, prepared by Sandis and last

revised January 26, 2017, indicates two of the buildings are built up to the southern property line

and three of the buildings are set-back about 4, 14, and 19-1/2 feet from the southern property

line.

2 Unless otherwise noted, elevations in this report are based on topographic information shown on the

drawing titled “Topographic Survey,” prepared by Sandis, revised January 26, 2017, City of Berkeley Datum.

16-1193 6 March 27, 2017

Two 2-story residential buildings are located to the west of the site. The locations of these

buildings are shown in the aerial photo on Figure 2. We do not have information regarding the

foundations of these buildings but anticipate that they are supported on shallow foundations.

Topographic Survey, prepared by Sandis and last revised January 26, 2017, indicates there is a

driveway, about 12 feet wide, between the western property line and these residential buildings.

There is a San Francisco Bay Area Rapid Transit (BART) subway below Shattuck Avenue that

crosses the block to the north of the project site diagonally. The approximate alignment of the

BART right-of-way near the project site is shown on Figure 2. New construction located within

the BART subway’s zone-of-influence (ZOI), defined as a line extending upward at an

inclination of 1.5:1 (horizontal: vertical) from the base of the subway, will require measures to

be taken to avoid surcharging the subway structure. On November 1, 2016, we reviewed as-built

documents for the Berkeley-Richmond line near the site at the BART office in Oakland. Based

on the as-built documents we obtained from BART, the subway right-of-way is located about

38 feet northeast of the northeastern corner of the site and the base of the subway is about 42 feet

bgs. A generalized cross section showing the approximate location and depth of the BART

subway and the ZOI is presented on Figure 3.

4.2 Subsurface Conditions

As presented on the Regional Geologic Map (Figure 4), the site is underlain by Holocene-age

alluvial fan and fluvial deposits (Qhaf) (Graymer, 2000). Alluvial and fluvial deposits are

sediments deposited by rivers and streams.

The results of our borings indicate the site is underlain by medium stiff to hard clay with varying

sand and gravel content interbedded with occasional layers of medium dense to very dense

clayey sand to the maximum depth explored of 39 to 50 feet bgs. Generally, the sands and

gravels have moderate to high fines (clay and silt) content.

Two Atterberg limits tests were performed on selected samples of the near-surface clay (i.e.,

upper 1-1/2 to 3 feet) obtained from Borings B-3 and B-4. The Atterberg limits test results

16-1193 7 March 27, 2017

indicate the samples tested have plasticity indices (PI) of 16 and 21, which indicate the surficial

soil has moderate expansion potential3.

4.3 Groundwater

Groundwater was encountered during drilling in Borings B-3, B-4, and B-5. Groundwater was

measured at a depth of about 21 feet bgs in Boring B-3 after leaving the borehole open for about

three hours after completion of drilling. Groundwater was measured in Borings B-4 and B-5 at

depths of about 38 and 43 feet bgs, respectively, immediately following the completion of

drilling. The groundwater level measurements in Borings B-3, B-4, and B-5 were taken

immediately or shortly after completion of drilling and may not reflect stabilized groundwater

levels. The groundwater level at the site is expected to fluctuate several feet seasonally with

potentially larger fluctuations annually, depending on the amount of rainfall. Although this past

winter was not particularly dry, rainfall during the previous few winters has been well below

normal and, therefore, our groundwater readings likely do not reflect the high groundwater levels

following winters with above-normal rainfall.

To help estimate the highest potential groundwater level at the site, we reviewed data collected at

a nearby development for the University of California, Berkeley (UCB) and information on the

State of California Water Resources Control Board GeoTracker website

(http://geotracker.waterboards.ca.gov/).

To the east of the site, A3GEO performed a geotechnical study for UCB for the development

located on the northeastern corner of Shattuck Avenue and Berkeley Way. Twelve borings were

drilled using hollow-stem augers at the site. During drilling, groundwater was recorded at depths

ranging from 16 to 31 feet bgs about 15 to 40 minutes following the completion of drilling; we

judge these readings do not represent stabilized groundwater levels because there was

insufficient time for the groundwater to stabilize. One boring (Boring B-10 located about

170 feet east of Shattuck Avenue and 40 feet north of Berkeley Way) was converted to a

3 Expansive soil undergoes volumetric changes with changes in moisture content (i.e. it shrinks when

dried and swells when wetted).

16-1193 8 March 27, 2017

piezometer after drilling. Between August 2009 and January 2010, groundwater was measured

in the piezometer on four occasions at depths ranging from 11-1/2 to 14-1/2 feet bgs (A3GEO,

2015).

Several nearby sites with historical groundwater data on the GeoTracker website include

1929 University Avenue, which is approximately 700 feet southwest of the site, and 2009, 2011,

and 2015 Addison Street, which is approximately 700 feet south of the site. Data from 1929

University Avenue indicates that the depth to stabilized groundwater is about 18 feet bgs

(Schultze & Associates, Inc., 2013). The highest groundwater level measured at the Addison

Street site between October 1991 and August 1994 was at a depth of 13.4 feet bgs (Subsurface

Consultants, Inc., 1994). The ground surface elevation at these two locations is approximately

20 feet lower than the subject site. Based on this data, the groundwater flow direction appears to

be towards the south-southwest direction.

Considering the above groundwater data and the fact that our recent investigation was performed

following several years of drought, we conclude a design groundwater depth of 12 feet bgs

should be used for design of the proposed building.

5.0 SEISMIC CONSIDERATION

The results of our evaluation regarding seismic considerations for the project site are presented in

the following sections.

5.1 Regional Seismicity and Faulting

The site is located in the Coast Ranges geomorphic province of California that is characterized

by northwest-trending valleys and ridges. These topographic features are controlled by folds and

faults that resulted from the collision of the Farallon plate and North American plate and

subsequent strike-slip faulting along the San Andreas Fault system. The San Andreas Fault is

more than 600 miles long from Point Arena in the north to the Gulf of California in the south.

The Coast Ranges province is bounded on the east by the Great Valley and on the west by the

Pacific Ocean.

16-1193 9 March 27, 2017

The major active faults in the area are the Hayward, Calaveras, San Andreas, and San Gregorio.

These and other faults in the region are shown on Figure 5. For these and other active faults

within a 50-kilometer radius of the site, the distance from the site and estimated mean

characteristic Moment magnitude4 [2007 Working Group on California Earthquake Probabilities

(WGCEP) (USGS 2008) and Cao et al. (2003)] are summarized in Table 1.

4 Moment magnitude is an energy-based scale and provides a physically meaningful measure of the

size of a faulting event. Moment magnitude is directly related to average slip and fault rupture area.

16-1193 10 March 27, 2017

TABLE 1 Regional Faults and Seismicity

Fault Segment Approximate Distance from

Site (km)

Direction from Site

Mean Characteristic

Moment Magnitude

Total Hayward 1.3 Northeast 7.0

Total Hayward-Rodgers Creek 1.3 Northeast 7.3

Mount Diablo Thrust 20 East 6.7

Green Valley Connected 23 East 6.8

Total Calaveras 24 East 7.0

N. San Andreas - Peninsula 28 West 7.2

N. San Andreas (1906 event) 28 West 8.1

Rodgers Creek 28 Northwest 7.1

N. San Andreas - North Coast 28 West 7.5

West Napa 33 North 6.7

San Gregorio Connected 33 West 7.5

Greenville Connected 38 East 7.0

Great Valley 5, Pittsburg Kirby Hills 41 East 6.7

Monte Vista-Shannon 48 South 6.5

Since 1800, four major earthquakes have been recorded on the San Andreas Fault. In 1836, an

earthquake with an estimated maximum intensity of VII on the Modified Mercalli (MM) scale

occurred east of Monterey Bay on the San Andreas Fault (Toppozada and Borchardt, 1998).

The estimated Moment magnitude, Mw, for this earthquake is about 6.25. In 1838, an earthquake

occurred with an estimated intensity of about VIII-IX (MM), corresponding to a Mw of about 7.5.

The San Francisco Earthquake of 1906 caused the most significant damage in the history of the

Bay Area in terms of loss of lives and property damage. This earthquake created a surface

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rupture along the San Andreas Fault from Shelter Cove to San Juan Bautista approximately

470 kilometers in length. It had a maximum intensity of XI (MM), a Mw of about 7.9, and was

felt 560 kilometers away in Oregon, Nevada, and Los Angeles. The most recent earthquake to

affect the Bay Area was the Loma Prieta Earthquake of October 17, 1989, with a Mw of 6.9.

This earthquake occurred in the Santa Cruz Mountains about 99 kilometers southwest of the site.

In 1868, an earthquake with an estimated maximum intensity of X on the MM scale occurred on

the southern segment (between San Leandro and Fremont) of the Hayward Fault. The estimated

Mw for the earthquake is 7.0. In 1861, an earthquake of unknown magnitude (probably a Mw of

about 6.5) was reported on the Calaveras Fault. The most recent significant earthquake on this

fault was the 1984 Morgan Hill earthquake (Mw = 6.2).

The U.S. Geological Survey's 2014 Working Group on California Earthquake Probabilities has

compiled the earthquake fault research for the San Francisco Bay area in order to estimate the

probability of fault segment rupture. They have determined that the overall probability of

moment magnitude 6.7 or greater earthquake occurring in the San Francisco Region during the

next 30 years (starting from 2014) is 72 percent. The highest probabilities are assigned to the

Hayward Fault, Calaveras Fault, and the northern segment of the San Andreas Fault. These

probabilities are 14.3, 7.4, and 6.4 percent, respectively.

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5.2 Geologic Hazards

Because the project site is in a seismically active region, we evaluated the potential for

earthquake-induced geologic hazards including ground shaking, ground surface rupture,

liquefaction,5 lateral spreading,6 and cyclic densification7. We used the results of our field

investigation to evaluate the potential of these phenomena occurring at the project site.

5.2.1 Ground Shaking

The seismicity of the site is governed by the activity of the Hayward Fault, although ground

shaking from future earthquakes on other faults, including the San Andreas, Calaveras, and San

Gregorio faults, will also be felt at the site. The intensity of earthquake ground motion at the site

will depend upon the characteristics of the generating fault, distance to the earthquake epicenter,

and magnitude and duration of the earthquake. The site is less than two kilometers from the

Hayward Fault. We judge that strong to very strong ground shaking could occur at the site

during a large earthquake on one of the nearby faults.

5.2.2 Liquefaction and Associated Hazards

When a saturated, cohesionless soil liquefies, it experiences a temporary loss of shear strength

created by a temporary rise in excess pore pressure generated by strong ground motion. Soil

susceptible to liquefaction includes loose to medium dense sand and gravel, low-plasticity silt,

and some low-plasticity clay deposits. Flow failure, lateral spreading, differential settlement,

loss of bearing strength, ground fissures and sand boils are evidence of excess pore pressure

generation and liquefaction.

5 Liquefaction is a phenomenon where loose, saturated, cohesionless soil experiences temporary

reduction in strength during cyclic loading such as that produced by earthquakes. 6 Lateral spreading is a phenomenon in which surficial soil displaces along a shear zone that has

formed within an underlying liquefied layer. Upon reaching mobilization, the surficial blocks are transported downslope or in the direction of a free face by earthquake and gravitational forces.

7 Cyclic densification is a phenomenon in which non-saturated, cohesionless soil is compacted by earthquake vibrations, causing ground-surface settlement.

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The site is not located within an area of Berkeley that is designated as a potential liquefaction

hazard zone on the map prepared by CGS titled State of California, Seismic Hazard Zones,

Oakland West Quadrangle, Official Map, dated February 14, 2003 (Figure 6). We evaluated the

liquefaction potential of soil encountered below groundwater at the site using data collected in

our borings. Considering the soil encountered in our borings below the design groundwater level

(12 feet bgs) generally consists of very stiff to hard clay and dense clayey sand, we judge the soil

is not susceptible to liquefaction because of its cohesion or high relative density. Therefore, we

conclude the potential for liquefaction to occur at the site is very low.

5.2.3 Cyclic Densification

Cyclic densification (also referred to as differential compaction) of non-saturated sand (sand

above groundwater table) can occur during an earthquake, resulting in settlement of the ground

surface and overlying improvements.

The results of our borings indicate the soil above the groundwater at the site generally consists of

cohesive soil, interbedded with relatively dense granular soil, which are not susceptible to cyclic

densification due to its relatively high fines content and high density. Therefore, we conclude

the potential for ground surface settlement resulting from cyclic densification at the site is very

low.

5.2.4 Fault Rupture

Historically, ground surface displacements closely follow the trace of geologically young faults.

The site is not within an Earthquake Fault Zone, as defined by the Alquist-Priolo Earthquake

Fault Zoning Act, and no known active or potentially active faults exist on the site. We,

therefore, conclude the risk of fault offset at the site from a known active fault is very low. In a

seismically active area, the remote possibility exists for future faulting in areas where no faults

previously existed; however, we conclude the risk of surface faulting and consequent secondary

ground failure from previously unknown faults is also very low.

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6.0 DISCUSSIONS AND CONCLUSIONS

From a geotechnical standpoint, we conclude the site can be developed as planned, provided the

recommendations presented in this report are incorporated into the project plans and

specifications and implemented during construction. The primary geotechnical concerns at the

site are: 1) a design groundwater level that is near the proposed finished floor of the below-grade

level, 2) providing adequate foundation support, and 3) providing lateral support for the

proposed excavation while minimizing the impact on the surrounding improvements. These and

other geotechnical issues, as they pertain to the proposed development, are discussed in the

remainder of this section.

6.1 BART Subway Zone-of-Influence

As discussed above in Section 4.1, the BART subway right-of-way is located about 38 feet

northeast of the northeastern corner of the site and the bottom of the subway is about 42 feet bgs.

As shown on Figure 3, the BART ZOI line daylights about 13 feet inside the subject property

and the bottom of the ZOI is approximately 9 feet bgs at the northeastern corner of the site. The

BART guidelines state that “all structures shall be designed as not to impose any temporary or

permanent adverse effects including unbalanced loading and seismic loading, on the adjacent

BART subways”. Considering the proposed building will have one basement level that will

extend about 12 feet bgs (depending on foundation thickness), we anticipate the foundations for

the proposed building will derive support below the ZOI and will not impose any temporary or

permanent loads on the BART subway.

The BART guidelines also state that temporary shoring located within the ZOI “shall be required

to maintain at-rest soil condition and monitored for movement.” Therefore, temporary shoring

system along the eastern property line and within 50 feet horizontally from the BART right-of-

way should be designed for at-rest soil conditions. Although the BART guidelines do not state

installation of tiebacks is prohibited within the ZOI, it is our experience that tiebacks will not be

allowed with this zone.

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6.2 Design Groundwater Level

Based on the existing and historical groundwater level data presented in Section 4.3, we

conclude a groundwater depth of 12 feet bgs should be used for design. A permanent dewatering

system (underslab drainage system), as presented in Section 7.3, may be installed to reduce

hydrostatic pressures on floor slabs, basement walls, and building foundations. Alternatively, the

basement walls, building foundations, and mat/floor slabs extending below the design

groundwater level can be waterproofed and designed to resist hydrostatic pressures.

6.3 Foundations and Settlement

The moderately expansive near-surface clay at the site is subject to volume changes during

seasonal fluctuations in moisture content. These volume changes can cause cracking of

foundations and floor slabs supported on the clay. Considering the finished floor for the

basement level in the proposed building will be founded well below the depth where seasonal

moisture changes in the soil occurs, mitigation measures to address the potential adverse impacts

of the moderately expansive near-surface soil on slabs and foundations are not required.

The foundation level of the proposed building with a basement will be underlain by stiff to hard

clay that can support moderate building loads. From a geotechnical standpoint, the proposed

building may be supported on shallow foundations consisting of conventional spread footings or

a mat foundation. Where basement slab/mat will extend below the design groundwater level, an

underslab drainage system should be installed to reduce hydrostatic pressures.

Recommendations for an underslab drainage system are presented in Section 7.3. Alternatively,

the floor slab/mat can be waterproofed and the foundations designed to resist hydrostatic

pressures.

We estimate total and differential settlement of properly constructed spread footings or mat

foundation designed using the recommendations presented in Section 7.2 of this report will be

less than one inch and 1/2 inch over a 30-foot horizontal distance, respectively.

The presence of adjacent buildings should be taken into account when designing foundations for

the proposed building to avoid surcharging the adjacent below-grade walls or foundations. It

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will be necessary to determine the configuration and depth of adjacent below-grade walls and

foundations. If as-built plans cannot be obtained, test pits should be excavated prior to

construction to determine adjacent below-grade wall depth, if any, and foundation type and

depth, as appropriate.

6.4 Underpinning

Underpinning of neighboring structures may be needed if excavations will be adjacent to and

extend below the elevation of the bottom of the foundations for adjacent structures. To

determine the need for underpinning and, if underpinning is needed, to provide information for

design of the underpinning system, it will be necessary to determine the configuration and depth

of existing foundations that bottom above an imaginary line extending up at an inclination of

1.5:1 from proposed excavations. If as-built plans cannot be obtained, test pits should be

excavated prior to construction to determine the foundation type and depth to complete the

design of an appropriate underpinning system. We can evaluate the extent of underpinning

required once the location of new foundation elements relative to existing foundations is

determined.

We conclude the most appropriate underpinning method would be hand-excavated end-bearing

piers. Hand-excavated, end bearing piers are generally installed by excavating three-foot by

five-foot rectangular shafts a minimum of two feet below the proposed basement excavation

depth, installing reinforcing steel, and backfilling with structural concrete. The shafts are

constructed in incremental phases to maintain support for the existing foundation. Each shaft is

shored with timber as it is excavated. The cut between adjacent shafts can be shored with timber

lagging as the excavation proceeds.

Where underpinning will extend relatively deep, it may be more economical to use slant drilled

cast-in-place soldier piles. This alternative should be further evaluated once the elevation of

adjacent foundations is known.

Underpinning piers will extend beneath the neighboring properties, which will require an

encroachment agreement with neighboring property owners. If it is not feasible to install the

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underpinning piers beneath the adjacent property, the basement wall should be offset from the

property line by at least 18 inches to provide space for the shoring and the shoring should be

designed to resist surcharge loads from neighboring foundations in addition to at-rest soil

pressures.

6.5 Temporary Cut Slope and Shoring

Excavations that will be deeper than five feet and will be entered by workers should be sloped or

shored in accordance with CAL-OSHA standards (29 CFR Part 1926). The shoring engineer

should be responsible for shoring design. The contractor should be responsible for the

construction and safety of temporary slopes.

We anticipate an excavation extending up to about 12 feet bgs will be needed to construct the

below-grade parking garage and foundations. If parking lifts will be installed in the basement

level, we anticipate the excavation may extend up to a depth of about 18 feet bgs. We judge that

temporary cuts in clay which are less than 12 feet high, above groundwater, and inclined no

steeper than 1:1 (horizontal:vertical) will be stable provided they are not surcharged by

equipment, building foundations, or building material. Temporary shoring will be required

where temporary slopes are not possible because of space constraints. There are several key

considerations in selecting a suitable shoring system. Those we consider of primary concern are:

protection of surrounding improvements, including roadways, utilities, and adjacent structures

proper construction of the shoring system to reduce potential for ground movement

cost.

Several methods of shoring are available; we have qualitatively evaluated the following systems:

conventional soldier pile and lagging with or without tie backs

soil nails.

We judge that a soldier pile and timber lagging shoring system would be the most appropriate

shoring type for this project. A soldier pile and lagging shoring system usually consists of steel

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H-beams and concrete placed in predrilled holes extending below the bottom of the excavation.

Wood lagging is placed between the piles as the excavation proceeds. Where the required cut is

less than about 14 feet, a soldier pile and lagging system can typically provide economical

shoring without tiebacks and, therefore, will not encroach beyond the property line. Where cuts

exceed about 14 feet in height, soldier pile-and-lagging systems are typically more economical if

they include tiebacks. However, if tiebacks will extend beneath the streets and sidewalks and

adjacent properties, an encroachment agreement will be required with the City of Berkeley and

adjacent property owners. In our experience tiebacks will not be allowed within the BART ZOI.

If permission from the adjacent property owners or City of Berkeley cannot be obtained to install

tiebacks beneath their properties, then internal bracing will be required. It will be necessary to

provide between 12 and 18 inches of space between the property line and the face of the shoring

where the basement walls will be constructed adjacent to private property.

A soil-nail shoring system is an alternative soldier pile and lagging. Soil-nail shoring system

consists of reinforcing bars, which are grouted in predrilled holes through the face of the

excavation, and a reinforced shotcrete facing. Soil-nail shoring systems require a certain amount

of ground movement to mobilize their lateral resistance; for soil-nail shoring systems located

adjacent to existing structures, the soil-nail shoring system should be designed to limit lateral

movement to 1/2 inch. Furthermore, installation of soil-nail shoring systems requires temporary

vertical cuts on the face of excavation, about four feet in height, until each section of soil-nails

are installed and shotcrete facing is constructed. Therefore, soil-nail shoring systems are

appropriate for excavations in stiff clay where temporary vertical cuts are achievable. The

results of our Borings B-1, B-2, B-3, and B-5 indicate the subsurface soil in the upper 12 feet is

primarily sandy clay with gravel along the western and southern property line; at Boring B-4,

located at the northeastern portion of the site, the upper 9 feet of soil consists of medium dense

clayey sand that is not appropriate for installation of soil nails.

The safety of workers and equipment in or near the excavation is the responsibility of the

contractor. The selection, design, construction, and performance of the shoring system should be

the responsibility of the contractor. A structural engineer knowledgeable in this type of

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construction should design the shoring. Recommendations for the design and construction of a

soil-nail and soldier pile and lagging shoring systems are presented in Section 7.7.

Neighboring buildings are present in some locations outside the proposed excavation. Where the

foundations of neighboring buildings are within the zone of influence of the excavation, defined

by a 1.5:1 (horizontal:vertical) plane extending up from the bottom of excavation, the shoring

system should to be designed to limit lateral movement to less than 1/2 inch. A monitoring

program should be implemented during construction to monitor vertical and lateral movement of

improvements surrounding the site.

6.6 Excavation Dewatering

We anticipate excavations for the basement garage, parking lift pits, and foundations may extend

below the design groundwater level. The actual groundwater level at the time of construction is

uncertain. If construction is performed during the wet season, the water level may be close to the

design groundwater level and some level of dewatering will likely be required. We anticipate

dewatering can be performed, where necessary, using a passive system consisting of trench

drains and sump pumps. The need for, selection, and design of a dewatering system for the

project is the responsibility of the contractor.

6.7 Excavation, Monitoring, and Construction Considerations

The soil to be excavated for the proposed foundations and utilities is expected to consist

primarily of sandy clay with gravel which can be excavated with conventional earth-moving

equipment such as backhoes.

There are existing buildings adjacent to the site. Heavy equipment should not be used within

10 horizontal feet from adjacent buildings. Jumping jack or hand-operated vibratory plate

compactors should be used for compacting fill within this zone.

During excavation, the shoring system may deform laterally, which could cause the ground

surface adjacent to the shoring to settle. The magnitudes of shoring movements and the resulting

settlements are difficult to estimate because they depend on many factors, including the method

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of installation and the contractor's skill in the shoring installation. Ground movements due to a

properly designed and constructed shoring system should be within ordinary accepted limits of

about one inch where there are no improvements within a horizontal distance equal to 1.5 times

the height of the shoring and 1/2 inch where there are improvements within that horizontal

distance. A monitoring program should be established to evaluate the effects of the excavation

on the adjacent buildings and surrounding ground.

The contractor should establish survey points on the shoring and on adjacent buildings and

streets within 25 feet of the excavation perimeter prior to the start of excavation. Temporary

shoring located within the BART ZOI should also be monitored per BART requirements. The

survey points should be used to monitor the vertical and horizontal movements of the shoring

and surrounding structures and streets during construction. The contractor should also survey

and take photographs of existing buildings within a horizontal distance of 25 feet of the proposed

excavation limits prior to the start of construction.

6.8 Soil Corrosivity

Laboratory testing was performed by Sunland Analytical of Rancho Cordova, California on two

samples of soil obtained during our field investigation from Borings B-4 at a depth of 2 feet bgs

and B-5 at a depth of 5-1/2 feet bgs. The results of the test are presented in Appendix B of this

report.

Based on the results of the pH test for B-5, which indicate the near-surface soil has a pH of 6.0,

we conclude the soil at this site is “moderately corrosive” to buried metal. Furthermore, the

resistivity test results indicate the sample is “moderately corrosive.” Accordingly, all buried

iron, steel, cast iron, ductile iron, galvanized steel and dielectric-coated steel or iron may need to

be protected against corrosion depending upon the critical nature of the structure. If it is

necessary to have metal in contact with soil, a corrosion engineer should be consulted to provide

recommendations for corrosion protection. The results indicate that sulfate ion concentrations

are sufficiently low such that they do not to pose a threat to buried concrete. In addition, the

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chloride ion concentrations are insufficient to impact steel reinforcement in concrete structures

below ground adversely.

7.0 RECOMMENDATIONS

Recommendations regarding site grading, temporary shoring, foundation support, basement wall

design, and other geotechnical aspects of the project are presented in this section.

7.1 Site Preparation and Grading

Site demolition should include the removal of existing pavements and all existing underground

utilities. Demolished asphalt concrete should be taken to an asphalt recycling facility.

Demolished concrete and aggregate base beneath existing pavements may be re-used as select

fill if carefully segregated. Any vegetation and the upper 3 to 4 inches of organic topsoil should

be stripped in areas to receive improvements (i.e., building, pavement, or flatwork).

In general, abandoned underground utilities should be removed to the property line or service

connections and properly capped or plugged with concrete. Where existing utility lines are

outside of the proposed building footprint and will not interfere with the proposed construction,

they may be abandoned in place provided the lines are filled with lean concrete or cement grout

to the property line. Any excavations created during demolition should be properly backfilled

with compacted fill under the observation of our field engineer.

During demolition of the existing site improvements, care should be taken by the contractor to

ensure that excessive vibrations of the ground close to the adjacent structures do not occur. Any

piece of pneumatic machinery used in the demolition process should be restricted to working at

the center of the site, away from the adjacent buildings.

7.1.1 Soil Subgrade Preparation

We anticipate the soil subgrade for the basement slab/mat will consist of firm native soil with

near optimum moisture content. Therefore, scarifying, moisture conditioning and recompacting

the soil subgrade for the basement slab/mat will not be required. The basement slab/mat

subgrade should be proof-rolled prior to being covered up with mud slab or improvements.

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Excavation for the building pad subgrade will likely expose native moderately expansive clay.

The subgrade will be near or below the design groundwater level, and the exposed material may

be wet and sensitive to disturbance from equipment. Care should be taken to minimize

disturbance to the building pad subgrade during excavation. Heavy rubber-tired equipment

should not be driven on the subgrade to reduce the potential for subgrade “pumping.” We

recommend only tracked equipment be used when the excavation approaches two feet of the

subgrade elevation. Even with lightweight tracked equipment, soft subgrade areas may be

encountered. If soft areas are encountered in the building pad subgrade, subgrade stabilization

measures may be required. Recommendations for soil subgrade stabilization are presented in

Section 7.1.2.

7.1.2 Soil Subgrade Stabilization

In some areas, soft, wet soil may be exposed during excavation causing the subgrade to deflect

and rut under the weight of grading equipment. In these areas, some form of subgrade

stabilization may be required. Several options for stabilizing subgrade exist, as presented below.

Aeration

Aeration consists of mixing and turning the soil to lower the moisture content to an acceptable

level. Aeration typically requires several days to a week of warm, dry weather to effectively dry

the material. Material to be dried by aeration should be scarified to a depth of at least 12 inches;

the scarified material should be turned at least twice a day to promote uniform drying. Once the

moisture content of the aerated soil has been reduced to acceptable levels, the soil should be

compacted in accordance with our previous recommendations. Aeration is typically the least

costly subgrade stabilization alternative; however, it generally requires the most time to complete

and may not be effective in locations where the excavation is near the groundwater table.

Overexcavation

Another method of achieving suitable subgrade in areas where soft, wet soil is exposed is to

overexcavate the soft subgrade soil and replace it with drier, granular material. If the soft

material extends to great depths, the upper 18 to 24 inches of soft material may be overexcavated

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and a geotextile tensile fabric (Mirafi 500X or equivalent) placed beneath the granular backfill to

help span over the weaker material. The fabric should be pulled tight and placed at the base of

the overexcavation, extending at least two feet laterally beyond the limits of the overexcavation

in all directions. The fabric should be overlapped by at least two feet at all seams. Granular

material such as Class 2 aggregate base (AB) should then be placed and compacted over the

geotextile tensile fabric. Where the overexcavation extends below the groundwater, the granular

backfill should consist of drain rock. Drain rock should be overlain by geotextile filter or tensile

fabric (Mirafi 140NC or equivalent) to form a separation between the open-graded rock and soil

backfill placed above the rock.

Where very soft subgrade conditions are encountered, a geogrid, such as Tensar TriAx TX140 or

equivalent, may be required in lieu of tensile fabric. Where geogrids are used the depth of

overexcavation will likely be on the order of 12 to 18 inches. The geogrids should be overlapped

by at least two feet and tied with hog rings or nylon ties at a spacing not to exceed 10 feet. The

geogrids should be covered with a well-graded granular fill such as Class 2 AB; open-graded

rock should not be used. All backfill placed over the geogrid should be compacted in accordance

with our previous recommendations.

Chemical Treatment

Lime and/or cement have been successfully used to dry and stabilize fine-grained soils with

varying degrees of success. Lime- and/or cement-treatment will generally decrease soil density,

change its plasticity properties, and increase its strength. The degree to which lime will react

with soil depends on such variables as type of soil, mineralogy, quantity of lime, and length of

time the lime-soil mixture is cured. Cement is generally used in when a significant amount of

granular material or low-plasticity silt is present in the soil. The quantity of lime and/or cement

added generally ranges from 3 to 7 percent by weight and should be determined by laboratory

testing. The specialty contractor performing the chemical treatment should select the most

appropriate additive and quantity for the soil conditions encountered.

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If chemical treatment is used to stabilize soft subgrade, a treatment depth of about 18 inches

below the final soil subgrade will likely be required. The soil being treated should be scarified

and thoroughly broken up to full depth and width. The treated soil should not contain rocks or

soil clods larger than three inches in greatest dimension. Treated soil should be compacted to at

least 90 percent relative compaction8 (RC), and at least 95 percent RC in the upper six inches of

pavement subgrade.

7.1.3 Fill Materials and Compaction Criteria

On-site soil may be used as fill or backfill, provided it is free of organic matter, contains no rocks

or lumps larger than three inches in greatest dimension, and is approved by the Geotechnical

Engineer. Fill consisting of imported soil (select fill) should be free of organic matter, contain

no rocks or lumps larger than three inches in greatest dimension, have a liquid limit of less than

40 and a plasticity index lower than 12, and be approved by the Geotechnical Engineer. Samples

of proposed imported fill material should be submitted to the Geotechnical Engineer at least

three business days prior to use at the site. The grading contractor should provide analytical test

results or other suitable environmental documentation indicating the imported fill is free of

hazardous materials at least three days before use at the site. If this data is not available, up to

two weeks should be allowed to perform analytical testing on the proposed imported material.

Fill should be placed in horizontal lifts not exceeding eight inches in uncompacted thickness,

moisture-conditioned to above optimum moisture content, and compacted to at least 90 percent

RC. Fill material consisting of clean sand or gravel (defined as soil with less than 10 percent

fines by weight) should be compacted to at least 95 percent RC. Fill greater than five feet in

thickness or fill placed within the upper eight inches of vehicular pavement soil subgrade should

also be compacted to at least 95 percent RC, and be non-yielding.

8 Relative compaction refers to the in-place dry density of soil expressed as a percentage of the

maximum dry density of the same material, as determined by the ASTM D1557 laboratory compaction procedure.

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Where the recommended compaction requirements are in conflict with the City of Berkeley

standard details for pavements, sidewalks, or trenches within the public right-of-way, the City

Engineer or inspector should determine which compaction requirements should take precedence.

Controlled Low Strength Material

Controlled low strength material (CLSM) may be considered as an alternative to fill beneath the

building, concrete flatwork, or pavement. CLSM should meet the requirements in the

2015 Caltrans Standard Specifications. It is an ideal backfill material when adequate room is

limited or not available for conventional compaction equipment, or when settlement of the

backfill must be minimized. No compaction is required to place CLSM. CLSM should have a

minimum 28-day unconfined strength of 50 pounds per square inch (psi).

7.1.4 Utility Trench Backfill

Excavations for utility trenches can be readily made with a backhoe. All trenches should

conform to the current CAL-OSHA requirements. To provide uniform support, pipes or conduits

should be bedded on a minimum of four inches of sand or fine gravel. After the pipes and

conduits are tested, inspected (if required) and approved, they should be covered to a depth of

six inches with sand or fine gravel, which should be mechanically tamped.

Backfill for utility trenches and other excavations is also considered fill, and should be placed

and compacted as according to the recommendations previously presented. If imported clean

sand or gravel (defined as soil with less than 10 percent fines) is used as backfill, it should be

compacted to at least 95 percent relative compaction. Jetting of trench backfill should not be

permitted. Special care should be taken when backfilling utility trenches in pavement areas.

Poor compaction may cause excessive settlements, resulting in damage to the improvements

above the fill.

Foundations for the proposed structures should be bottomed below an imaginary line extending

up at a 1.5:1 (horizontal to vertical) inclination from the base of the utility trenches running

parallel to the foundation. Alternatively, the portion of the utility trench (excluding bedding) that

is below the 1.5:1 line can be backfilled with CLSM. If utility trenches are to be excavated

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below this zone-of-influence line after the construction of the building foundations, the trench

walls need to be fully supported with shoring until CLSM is placed.

7.1.5 Exterior Flatwork Subgrade Preparation

We recommend a minimum of four inches of Class 2 AB be placed below exterior concrete

flatwork, including patio slabs and sidewalks; the AB should extend at least six inches beyond

the slab edges where adjacent to landscaping. Class 2 AB beneath exterior slabs-on-grade, such

as patios and sidewalks, should be compacted in accordance with the requirements provided

above in Section 7.1.3.

7.2 Foundations

Our recommendations for spread footing and mat foundations are presented in this section.

7.2.1 Spread Footings

The proposed building may be supported on conventional spread footings bearing on firm native

soil. Continuous footings should be at least 18 inches wide and isolated spread footings should

be at least 24 inches wide. Footings should be bottomed at least 18 inches below the lowest

adjacent soil subgrade.

The footings may be designed using allowable bearing pressures of 5,000 pounds per square foot

(psf) for dead-plus-live loads; this value may be increased by one-third for total design loads,

which include wind or seismic forces. These allowable bearing capacities include factors of

safety of at least 2.0 and 1.5 for dead-plus-live loads and total loads, respectively.

Lateral loads can be resisted by a combination of passive pressure on the vertical faces of the mat

and friction along the bottom of the mat. Lateral resistance may be computed using an allowable

passive pressure of 2,000 psf (uniform distribution) for transient loads, including wind and

seismic, and equivalent fluid weights (triangular distribution) of 260 and 125 pounds per cubic

foot (pcf) for sustained loads above and below the design groundwater table, respectively.

Passive resistance in the upper one foot of soil should be ignored unless it is confined by slabs or

pavement. To compute frictional resistance, we recommend using a friction coefficient of 0.3.

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The above-recommended passive pressure and frictional resistance values include a factor of

safety of at least 1.5 and may be used in combination without reduction.

Footing excavations should be free of standing water, debris, and disturbed materials prior to

placing concrete. If footings are excavated during the rainy season and/or whether the

excavations extend below the groundwater level at the time of construction, they should

incorporate a rat slab to protect the footing subgrade. This will involve over-excavating the

footing by about two inches and placing lean concrete or sand-cement slurry in the bottom

(following inspection by our engineer). A rat slab will help protect the footing subgrade during

placement of reinforcing steel. Water can then be pumped from the excavations prior to

placement of structural concrete, if present. The bottoms and sides of the footing excavations

should be moistened following excavation and maintained in a moist condition until concrete is

placed. We should check footing excavations prior to placement of reinforcing steel.

7.2.2 Mat Foundation

For structural design of the mat foundation, we recommend using an initial coefficient of vertical

subgrade reaction of 40 pounds per cubic inch (pci) under DL+LL conditions; this value may be

increased by 50 percent for total load conditions. The coefficient of vertical subgrade values

have been reduced to account for the size of the mat/equivalent footings (therefore, this is not kv1

for 1-foot-square plate). We recommend the mat be designed using an allowable bearing

pressure of 5,000 pounds per square foot (psf) for dead-plus-live loads; we anticipate the average

bearing pressure will be significantly lower. This value may be increased by one-third for total

loads (including seismic and wind loads).

Lateral loads can be resisted by a combination of passive pressure on the vertical faces of the mat

and friction along the bottom of the mat. Lateral resistance may be computed using an allowable

passive pressure of 2,000 psf (uniform distribution) for transient loads, including wind and

seismic, and equivalent fluid weights (triangular distribution) of 260 and 125 pcf for sustained

loads above and below the groundwater table, respectively. Passive resistance in the upper one

foot of soil should be ignored unless it is confined by slabs or pavement. To compute frictional

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resistance, we recommend using a friction coefficient of 0.3 where the mat is in contact with the

soil. Where a vapor retarder is placed beneath the mat, a base friction coefficient of 0.20 should

be used. Where the mat is underlain by waterproofing membrane, the allowable friction factor

will depend on the type of waterproofing used at the base of the mat. For bentonite-based

waterproofing membranes, such as Paraseal or Voltex, a friction factor of 0.12 should be used

(assumes a bentonite friction angle of 10 degrees). If Preprufe is used, a base friction factor of

0.20 should be used. Friction factors for other types of waterproofing membranes can be

provided upon request. The above-recommended passive pressure and frictional resistance

values include a factor of safety of at least 1.5 and may be used in combination without

reduction.

The subgrade should be kept moist and be free of standing water, debris, and disturbed materials

and be checked by the project Geotechnical Engineer prior to being covered up by the underslab

drainage system or waterproofing. Where waterproofing will be installed, we recommend a rat

slab consisting of at least three inches of structural concrete or CLSM be placed on the mat

subgrade to protect the subgrade from softening from ponding water and/or disturbance from

foot traffic during construction, and to provide a working surface on which to install the

waterproofing system.

7.3 Underslab Drainage System

Where the garage floor slab will extend below the design groundwater level, an underslab

drainage system should be installed to reduce hydrostatic pressures. Alternatively, the floor

slab/mat can be waterproofed and the foundations and floor slab be designed to resist hydrostatic

pressures.

Based on our experience, we believe a permanent underslab drainage system to reduce

hydrostatic pressures may result in a more economical foundation design than a fully

waterproofed basement designed to resist hydrostatic pressures. We recommend the permanent

underslab drainage system consist of a series of 12-inch-wide trenches that are at least 12 inches

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deep and sloped to drain at an inclination of at least one percent to a sump. The trenches should

be spaced no more than 20 feet on center.

The garage slab subgrade (between the trenches) should be excavated to provide room for at

least six inches of Class 2 permeable material and should be sloped at an inclination of at least

two percent toward the subdrain trenches. The Class 2 permeable material should meet the

requirements of Caltrans Standard Specifications 68-1.025 most recent edition. The collection

pipes should consist of four-inch-diameter, Schedule 40, perforated PVC pipe (perforations

down). The pipes should be installed such that they are surrounded on all sides by at least four

inches of permeable material and a filter sock should be installed around the pipe to prevent the

finer particles of the Class 2 permeable material from entering the perforations.

The pipes should drain at a gradient of at least one percent to at least one sump pit location in the

garage level. Cleanouts should be provided to ensure the underslab drainage system can be

cleared if it becomes clogged. The sump-and-pump system should be designed to discharge

water directly to the storm drain system without allowing the water to build up beneath the slab-

on-grade floor. It is critical that the sump pump(s) remain functioning during periods of elevated

groundwater; therefore, back-up generators should be considered in the design of the sump-and-

pump system, if used. In the event that water is allowed to build up beneath the slab, structural

damage and flooding of the garage space may occur. Therefore, we recommend that “pop-off”

valves be installed in the floor slab to allow excess water to drain into the garage in case of

hydrostatic pressure build up beneath the floor slab.

7.4 Slab-on-Grade Floor

Where the garage floor slab will extend below the design groundwater level, an underslab

drainage system should be installed to reduce hydrostatic pressures or the slab be waterproofed

and designed to resist the hydrostatic uplift pressure. If an underslab drainage system will be

installed, the design of the underslab drainage system should consider the possibility that a

portion of the drainage system may fail, resulting in a build-up of hydrostatic pressures which

could damage the floor slab. Therefore, we recommend that “pop-off” valves be installed in the

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floor slab to allow excess water to drain into the garage in case of hydrostatic pressure build up

beneath the floor slab.

Where water vapor transmission through the floor slab is undesirable and waterproofing is not

installed below the floor slab, we recommend installing a water vapor retarder beneath the floor.

A vapor retarder is generally not required beneath parking garage floor slabs because there is

sufficient air circulation to allow evaporation of moisture that is transmitted through the slab;

however, we recommend the vapor retarder be installed below the slab-on-grade in utility rooms

and any areas in or adjacent to the parking garage that will be used for storage and/or will receive

a floor covering or coating.

The vapor retarder may be placed directly on the Class 2 permeable material. The vapor retarder

should meet the requirements for Class A vapor retarders stated in ASTM E1745. The vapor

retarder should be placed in accordance with the requirements of ASTM E1643. These

requirements include overlapping seams by six inches, taping seams, and sealing penetrations in

the vapor retarder.

If required by the structural engineer, the vapor retarder may be covered with two inches of sand

to aid in curing the concrete and to protect the vapor retarder during slab construction. The sand

overlying the vapor retarder should be moist at the time concrete is placed. However, excess

water trapped in the sand could eventually be transmitted as vapor through the slab. Therefore, if

rain is forecast prior to pouring the slab, the sand should be covered with plastic sheeting to

avoid wetting. If the sand becomes wet, concrete should not be placed until the sand has been

dried or replaced.

Concrete mixes with high water/cement (w/c) ratios result in excess water in the concrete, which

increases the cure time and results in excessive vapor transmission through the slab. Therefore,

concrete for the floor slab should have a low w/c ratio - less than 0.50. If approved by the

project structural engineer, the sand can be eliminated and the concrete can be placed directly

over the vapor retarder, provided the w/c ratio of the concrete does not exceed 0.45 and water is

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not added in the field. If necessary, workability should be increased by adding plasticizers. In

addition, the slab should be properly cured.

Before the floor covering is placed, the contractor should check that the concrete surface and the

moisture emission levels (if emission testing is required) meet the manufacturer’s requirements.

7.5 Permanent Below-Grade Walls

Below-grade walls should be designed to resist static lateral earth pressures, lateral pressures

caused by earthquakes, vehicular surcharge pressures, and surcharges from adjacent foundations,

where appropriate. We recommend restrained below-grade walls at the site be designed for the

more critical of the following criteria:

At-rest equivalent fluid weight of 55 pcf above the design groundwater table and 90 pcf below, plus a traffic increment where the wall will be within 10 feet of adjacent streets.

Active pressure of 40 pcf plus a seismic increment of 36 pcf (triangular distribution) above the design groundwater level, and 80 pcf below the groundwater level plus a seismic increment of 17 pcf (triangular distribution).

Where an underslab drainage system is installed and the basement wall is properly backdrained,

the entire height of basement wall may be designed using the recommended at-rest and active

plus seismic increment values for above the design groundwater level; we should address this

condition when the final depth of basement wall and dewatering system are available.

The recommended pressures above are based on a level backfill condition with no additional

surcharge loads. Where the permanent wall will be subject to vehicular loading within 10 feet of

the wall, an additional uniform lateral pressure of 50 psf applied to the upper 10 feet of the wall.

If neighboring building foundations are not underpinned and rest on soil above an imaginary line

that lies at an inclination of 1.5:1 (horizontal to vertical) projected upward from the bottom edge

of the basement wall, the basement wall should be designed for surcharge pressures from the

neighboring building foundations.

The lateral earth pressures recommended are applicable to walls that are backdrained to prevent

the buildup of hydrostatic pressure. One acceptable method for back-draining a basement wall is

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to place a prefabricated drainage panel against the back of the wall. The drainage panel should

extend down to the design groundwater table or to a perforated PVC collector pipe where the

wall bottoms above the design groundwater table. The pipe should be surrounded on all sides by

at least four inches of Caltrans Class 2 permeable material or 3/4-inch drain rock wrapped in

filter fabric (Mirafi NC or equivalent). A proprietary, prefabricated collector drain system, such

as Tremdrain Total Drain or Hydroduct Coil (or equivalent), designed to work in conjunction

with the drainage panel may be used in lieu of the perforated pipe surrounded by gravel

described above. The pipe should be connected to a suitable discharge point; a sump and pump

system may be required to drain the collector pipes, in the event the elevation is insufficient to

gravity drain to the storm drain system.

To protect against moisture migration, below-grade basement walls should be waterproofed and

water stops should be placed at all construction joints. In recent years, we have observed

numerous leaks in below-grade portions of buildings constructed with waterproofed, shotcrete

walls. In areas where there is a high sensitivity to leaks, we recommend cast-in-place concrete

be considered.

If backfill is required behind below-grade walls, the walls should be braced, or hand compaction

equipment used, to prevent unacceptable surcharges on walls (as determined by the structural

engineer).

7.6 Underpinning

Where hand-excavated underpinning piers are used to underpin adjacent foundations, the piers

should be designed to gain support through end bearing on firm native soil. An allowable

bearing pressure of 5,000 psf for dead-plus-live loads may be used for designing of underpinning

piers. The underpinning piers should extend at least 24 inches below the planned excavations for

the project or 24 inches above an imaginary line that lies at an inclination of 1.5:1 (horizontal to

vertical) projected upward from the bottom edge of the excavation. The width of the

underpinning piers should be determined by the project Structural Engineer or underpinning

designer based on the ability of the existing foundation to span an area of non-support. If fill or

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weak soil is encountered at the bottom of the underpinning piers, the excavation should be

deepened until suitable bearing firm native soil is encountered as directed by the project

Geotechnical Engineer in the field. Underpinning should be designed for unbalanced horizontal

loads resulting from the soil retained by the piers computed using an at-rest equivalent fluid

weight of 55 pcf above the design groundwater table and an at-rest equivalent fluid weight of

90 pcf below the design groundwater table, plus surcharge from adjacent foundations bearing

above an imaginary 1.5:1 (horizontal to vertical) line projected up from the bottom edge of the

excavation. Lateral resistance for underpinning piers may be computed using the passive

pressure and friction factor values for spread footings presented in Section 7.2.1 above.

7.7 Temporary Cut Slopes and Shoring

We anticipate excavations of about 12 and 18 feet bgs below existing grade will be needed to

construct the proposed one-level basement parking garage and parking lifts, respectively. The

soil to be excavated would consist of predominately clay, sand and gravel, which can be

excavated using conventional earth-moving equipment such as loaders and backhoes. We judge

that temporary slope cuts in clayey soils, corresponding to CAL-OSHA Types B soil, above the

groundwater table inclined no steeper than 1:1 (horizontal:vertical), will be stable provided that

they are not surcharged by equipment, adjacent building foundations, or building material.

Temporary shoring will be required where temporary slopes are not possible because of space

constraints. The shoring engineer should be responsible for shoring design. The contractor

should be responsible for the construction and safety of temporary slopes. We should review the

geotechnical aspects of the proposed shoring system to ensure that it meets our requirements.

During construction, we should observe the installation of the shoring system and check the

condition of the soil encountered during excavation.

As discussed in Section 6.5, we conclude soil-nail and soldier pile and lagging shoring systems

are appropriate for support of excavations for this project. Recommendations for soil-nail and

soldier pile and lagging temporary shoring systems are presented in this section.

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7.7.1 Cantilevered Soldier Pile and Lagging Shoring

We recommend the cantilevered soldier pile-and-lagging shoring system be designed to resist an

active equivalent fluid weight of 40 pcf where the retained ground surface is level. In locations

where minimizing lateral deflections is critical, such as near adjacent buildings, near sensitive

underground utilities or within the BART ZOI, the shoring system should be designed to resist

an at-rest equivalent fluid weight of 55 pcf (level ground surface) plus any foundation surcharge

loads. Where traffic loads are expected within 10 feet of the shoring walls, an additional design

load of 50 psf should be applied to the upper 10 feet of the wall. Where construction equipment

will be working behind the walls within a horizontal distance equal to the wall height, the design

should include a surcharge pressure of 250 psf.

The above pressures should be assumed to act over the entire width of the lagging installed

above the excavation. The above pressures assume that during construction, groundwater, if

encountered, will seep through the lagging and will not build-up behind the soldier pile and

lagging temporary shoring system. Where appropriate, the shoring system should be designed to

resist the surcharge pressures imposed by adjacent structures. The surcharge pressures should be

evaluated when the foundation type, load, and elevation are known.

Passive resistance at the toe of the soldier pile should be computed using equivalent fluid

weights of 260 and 125 pcf above and below the groundwater table at the time of construction,

respectively; however, the passive pressure should be limited to 2,000 psf with depth. Passive

pressure can be assumed to act over an area of three soldier pile widths assuming the toe of the

soldier pile is filled with structural concrete. The shoring designer should check that the

specified minimum concrete strength is sufficient to spread the anticipated loads to three soldier

pile widths. If the soldier piles are vibrated into place, rather than being placed into drilled holes

with concrete, then the passive pressure should only be applied to three beam flange widths.

These passive pressure values include a factor of safety of at least 1.5.

Soldier piles should be placed in pre-drilled holes backfilled with concrete or installed in soil-

mix columns. The subsurface soils include lenses of clayey sands. Therefore, the shoring

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contractor should be prepared to use casing or drilling slurry to reduce caving of holes, where

necessary. Installing soldier piles using a vibratory method is not recommended within 25 feet

of existing structures.

The penetration of the soldier piles must be sufficient to ensure stability and resist the downward

loading of tiebacks. Vertical loads can be resisted by skin friction along the portion of the

soldier piles below the excavation. We recommend using an allowable skin friction value of

1,000 psf to compute the required soldier pile embedment. End bearing should be neglected.

7.7.2 Soldier Pile and Lagging Shoring System with Tiebacks

Recommended lateral pressures for the design of soldier pile and lagging shoring with tiebacks

are presented on Figure 7. Where it is not feasible to install tiebacks, then internal bracing of the

excavation will be required. Internal bracing should be preloaded to limit movement of the

shoring. In calculating these design pressures, we assumed drained conditions with no

hydrostatic pressure acting on the shoring. Where traffic loads are expected within 10 feet of the

shoring walls, an additional design load of 50 psf should be applied to the upper 10 feet of the

wall. Where construction equipment will be working behind the walls within a horizontal

distance of 10 feet, the design should include a surcharge pressure of 250 psf acting over the

upper 10 feet of the wall. The above pressures should be assumed to act over the entire width of

the lagging installed above the excavation. The shoring should be designed to resist the

surcharge pressures imposed by adjacent structures if the adjacent buildings are not underpinned.

The surcharge pressures should be evaluated when the foundation type, load, and elevation are

known.

Passive resistance at the toe of the soldier pile should be computed using equivalent fluid

weights of 260 and 125 pcf above and below the groundwater table, respectively, at the time of

construction; however, the passive pressure should be limited to 2,000 psf with depth. These

passive pressure values include a factor of safety of at least 1.5. The upper foot of soil should be

ignored when computing passive resistance. Passive pressure can be assumed to act over an area

of three soldier pile widths, or pile-to-pile spacing, whichever is less, assuming the toe of the

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soldier pile is filled with concrete or lean concrete that is sufficiently strong to accommodate the

corresponding stresses.

Soldier piles should be placed in pre-drilled holes backfilled with concrete or installed in soil-

mix columns. There are interbedded lenses of sands and gravels, therefore, the shoring

contractor should be prepared to use casing or drilling slurry to reduce caving of holes, where

necessary. Installing soldier piles using a vibratory method is not recommended within 25 feet

of existing structures.

The penetration of the soldier piles must be sufficient to ensure stability and resist the downward

loading of tiebacks. Vertical loads can be resisted by skin friction along the portion of the

soldier piles below the excavation. We recommend using an allowable skin friction value of

1,000 psf to compute the required soldier pile embedment. End bearing should be neglected.

Design criteria for tiebacks are also presented on Figure 7. As shown, tiebacks should derive

their load-bearing capacity from the soil behind an imaginary line sloping upward from a point

H/5 feet away from the bottom of the excavation at an angle of 60 degrees from horizontal,

where H is the wall height in feet. The minimum stressing lengths for strand and bar tendons

should be 15 and 10 feet, respectively. The minimum bond length for strand and bar tendons

should both be 15 feet.

Allowable capacities of the tiebacks will depend upon the drilling method, hole diameter, grout

pressure, and workmanship. The shoring contractor should use a smooth-cased method (such as

a Klemm rig) to install the tiebacks beneath adjacent buildings, where applicable. The shoring

designer should be responsible for determining the actual length of tiebacks required to resist the

design loads. The determination should be based on the designer’s familiarity with the

installation method to be used.

Tieback Testing

The computed bond length of tiebacks should be confirmed by a performance- and proof-testing

program under the observation of our field engineer. The first two production tiebacks and two

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percent of the remaining tiebacks should be performance tested to 1.5 times the design load. The

remaining tiebacks should be confirmed by a proof-test to 1.25 times the design load. The

movement of each tieback should be monitored with a free-standing, tripod-mounted dial gauge

during performance and proof testing. The bottom of excavation should not extend more than

two feet below a row of unsecured tiebacks.

The performance test is used to verify the capacity and the load-deformation behavior of the

tiebacks. It is also used to separate and identify the causes of tieback movement, and to check

that the designed unbonded length has been established. In the performance test, the load is

applied to the tieback in several cycles of incremental loading and unloading. During the test,

the tieback load and movement are measured. The maximum test load should be held for a

minimum of 10 minutes, with readings taken at 0, 1, 3, 6, and 10 minutes. If the difference

between the 1- and 10-minute reading is less than 0.04 inch during the loading, the test is

discontinued. If the difference is more than 0.04 inch, the holding period is extended by 50

minutes to 60 minutes, and the movements should be recorded at 15, 20, 25, 30, 45, and 60

minutes.

A proof test is a simple test used to measure the total movement of the tieback during one cycle

of incremental loading. The maximum test load should be held for a minimum of 10 minutes,

with readings taken at 0, 1, 2, 3, 6, and 10 minutes. If the difference between the 1- and 10-

minute reading is less than 0.04 inch, the test is discontinued. If the difference is more than 0.04

inch, the holding period is extended by 50 minutes to 60 minutes, and the movements should be

recorded at 15, 20, 25, 30, 45, and 60 minutes.

We should evaluate the tieback test results and determine whether the tiebacks are acceptable. A

performance- or proof-tested tieback with a 10-minute hold is acceptable if the tieback carries

the maximum test load with less than 0.04 inch movement between 1 and 10 minutes, and total

movement at the maximum test load exceeds 80 percent of the theoretical elastic elongation of

the unbonded length.

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A performance- or proof-tested tieback with a 60-minute hold is acceptable if the tieback carries

the maximum test load with less than 0.08 inch movement between 6 and 60 minutes, and total

movement at the maximum test load exceeds 80 percent of the theoretical elastic elongation of

the unbonded length. Tiebacks that failed to meet the first criterion will be assigned a reduced

capacity.

7.7.3 Soil-Nail Shoring System

All or portions of the proposed excavation along the western and southern property lines may be

supported by a soil nail shoring system. Soil nail walls should be designed to resist static lateral

earth pressures, as well as traffic loads, construction equipment loads, and foundation surcharge

loads, where applicable. In general, we recommend the walls be designed and constructed in

accordance with the guidelines presented in the Federal Highway Administration report on soil

nail walls (FHWA, 2015)9. Several computer programs, such as SNAIL (California Department

of Transportation, 2014) and GoldNail (Golder Associates, 1996), are available for designing a

soil-nail wall. SNAIL uses a force equilibrium method of analysis; the failure planes are

assumed bi-linear if they pass through the toe of the wall and tri-linear if they pass below the toe

of the wall. GoldNail uses a slope-stability model that satisfies overall limiting equilibrium of

free bodies defined by circular slip surfaces.

Soil-nail systems are typically installed under a design-build contract by specialty contractors;

therefore, we are not providing a specific design. However, we are providing estimated input

parameters for preliminary design. The actual capacities and lengths should be determined by

the design-build contractor with experience designing, building, and testing soil-nail walls in

similar soil conditions. We should review the design prior to installation. For preliminary

design, we recommend the input parameters presented in Table 2.

9 Federal Highway Administration (2003), Geotechnical Engineering Circular No. 7 – Soil Nail Walls,

March 2003 (FHWA Report No. FHWA0-IF-03-017)

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TABLE 2 Recommended Input Parameters for Design of Soil-Nail Walls

Soil Type1 Total

Density (pcf)

Ultimate Bond Strength (psf)

(Factor of Safety = 1.0)

Shear Strength Parameters

c2 3

(psf) (deg)

Sandy Clay 120 1,000 2,000 0

Notes: 1 Assume upper 12 feet of soil consists of sandy clay. 2 Cohesion intercept or undrained shear strength, without a factor of safety 3 Angle of internal friction, without a factor of safety

The soil-nail wall should be backdrained using two-foot-wide prefabricated drainage panels

between the nails. The panels should extend to a drainage pipe at the base of the wall that directs

the water to a suitable outlet or to weep holes at the base of the wall. Where construction

equipment will be working or driving upslope within 10 feet of the soil-nail wall, the design

should include a surcharge pressure of 250 psf. Where appropriate, the shoring system should be

designed to resist the surcharge pressures imposed by adjacent structures. The surcharge

pressures should be evaluated when the foundation type, load, and elevation are known. The

soil-nail wall should be designed with a minimum factor of safety of 1.5 against slope stability

failure for temporary walls.

We should be allowed to review the design plans and design calculations prior to their issuance

for construction to check for conformance with our recommendations. The design of the walls

should also include appropriate testing of soil-nails.

Soil-Nail Testing

We recommend the soil-nails be load-tested prior to and during construction in accordance with

the guidelines presented in the FHWA document titled Soil Nail Walls Reference Manual, dated

February 2015 (Report No. FHWA-NHI-14-007). Test nails should be installed using the same

equipment, method, and hole diameter as planned for the production nails. Verification and

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proof tests should be performed. Verification tests are performed prior to production nail

installation to verify the pullout resistance (bond strength) value used in design. Two

verification tests should be performed for each soil type assumed in design. Proof tests are

performed during construction to verify that the contractor’s procedure remains the same or that

the nails are not installed in a soil type not tested during the verification stage testing. At least

five percent of the production nails should be proof tested.

Tests should be performed on production or sacrificial nails to a test load corresponding to the

ultimate pullout resistance value used in the design. Test nails should have at least one foot of

unbonded length and 10 feet of bond length. The nail bar grade and size should be designed

such that the bar stress does not exceed 80 percent of its ultimate strength during testing.

The verification and proof tests should be performed in accordance with FHWA guidelines

(FHWA, 2015), including the recommended load increments, maximum test load, and failure

criteria. We should evaluate the test results and determine whether the test nail performance is

acceptable.

7.8 Seismic Design

For design in accordance with the 2016 California Building Code, we recommend Site Class D

be used. Using the USGS U.S. Seismic Design Maps website and the site latitude of 37.8728º

and longitude of -122.2699º we conclude the following seismic design parameters should be

used:

SS = 2.354 g, S1 = 0.979 g

SMS = 2.354 g, SM1 = 1.468 g

SDS = 1.569 g, SD1 = 0.979 g

Seismic Design Category E for Risk Categories I, II, and III.

8.0 GEOTECHNICAL SERVICES DURING CONSTRUCTION

Prior to construction, Rockridge Geotechnical should review the project plans and specifications

to verify that they conform to the intent of our recommendations. During construction, our field

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engineer should provide on-site observation and testing during site preparation, placement and

compaction of fill, and installation of temporary shoring, underpinning piers and foundations.

These observations will allow us to compare actual with anticipated soil conditions and to verify

that the contractor's work conforms to the geotechnical aspects of the plans and specifications.

9.0 LIMITATIONS

This geotechnical study has been conducted in accordance with the standard of care commonly

used as state-of-practice in the profession. No other warranties are either expressed or implied.

The recommendations made in this report are based on the assumption that the subsurface

conditions do not deviate appreciably from those disclosed in the test borings. If any variations

or undesirable conditions are encountered during construction, we should be notified so that

additional recommendations can be made. The foundation recommendations presented in this

report are developed exclusively for the proposed development described in this report and are

not valid for other locations and construction in the project vicinity.

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REFERENCES

2016 California Building Code

2015 Caltrans Standard Specifications

A3GEO (2015). Geotechnical Investigation Report, Berkeley Way Project, University of California, Berkeley, June 17.

California Geological Survey (2003). State of California Seismic Hazard Zones, Oakland West Quadrangle, Official Map, February 14, 2003.

California Department of Transportation, Division of New Technology, Materials and Research, Office of Geotechnical Engineering, (2014). SNAIL Program, A User Manual, updated December 2014, available from http://www.dot.ca.gov/hq/esc/geotech/software/geo_software.html.

Cao, T., Bryant, W. A., Rowshandel, B., Branum D. and Wills, C. J. (2003). “The Revised 2002 California Probabilistic Seismic Hazard Maps”

Field, E.H., and 2014 Working Group on California Earthquake Probabilities, (2015). UCERF3: A new earthquake forecast for California’s complex fault system: U.S. Geological Survey 2015-3009, 6 p., http://dx.doi.org/10.3133/fs20153009.

Federal Highway Administration, (2015). Soil Nail Walls Reference Manual, Publication Number FHWA-NHI-14-007, February.

GeoTracker website, State of California Water Resources Control Board, (http://geotracker.waterboards.ca.gov/), accessed November 4, 2016.

Golder Associates, (1996). GoldNail, A Stability Analysis Computer Program for Soil Nail Wall Design, Reference Manual Version 3.11, October 1996.

Graymer, R.W. (2000). Geologic map and map database of the Oakland metropolitan area, Alameda, Contra Costa, and San Francisco Counties, California: U.S. Geological Survey Miscellaneous Field Studies MF–2342, scale 1:50,000. (Available at http://pubs.usgs.gov/mf/2000/2342/.)

Sandis (2016). Topographic Survey, 2012 Berkeley Way, Revision 1, January 26, 2017.

Schultze & Associates, Inc. (2013). 1929 University Avenue, Berkeley, California, Report for: Installation of Two Monitoring Wells and First Quarterly Groundwater Monitoring Event, December 9.

Sitar, N. et al. (2012). Seismically Induced Lateral Earth Pressures on Retaining Structures and Basement Walls, ASCE GeoCongress 2012 Geotechnical Special Publiation No. 226.

16-1193 43 March 27, 2017

Subsurface Consultants, Inc. (1994). Final Report, Sumps and Hydraulic Hoists Removal, Soil and Groundwater Remediation, 2009, 2011, and 2015 Addison Street, Berkeley, California, October 21.

Toppozada, T.R. and Borchardt G. (1998). “Re-evaluation of the 1936 “Hayward Fault” and the 1838 San Andreas Fault Earthquakes.” Bulletin of Seismological Society of America, 88(1), 140-159.

U.S. Geological Survey (USGS) (2008). The Uniform California Earthquake Rupture Forecast, Version 2 (UCERF 2): prepared by the 2007 Working Group on California Earthquake Probabilities, U.S. Geological Survey Open File Report 2007-1437.

FIGURES

Project No. FigureDateROCKRIDGEGEOTECHNICAL 1

SITE LOCATION MAP

SITE

Base map: The Thomas Guide Alameda County 2002

0 1/2 Mile

Approximate scale

1/4

11/21/16 16-1193

2012 BERKELEY WAYBerkeley, California

0

Approximate scale

50 Feet

03/25/17 16-1193 2

Berkeley, California

SITE PLAN

Date Project No. Figure

ROCKRIDGEGEOTECHNICAL

Base map: Google Earth, 2016.

EXPLANATION

Approximate location of boring by RockridgeGeotechnical Inc., September 29 and 30, 2016

Approximate project limits

Approximate right-of-way of Bay Area RapidTransit (BART) limits

Location of generalized cross section showingzone-of-influence for BART Subway Structures,see Figure 3

BERKELEY WAY

HE

NR

Y S

TR

EE

T

B-1

B-2

B-1

B-5

B-4

B-3

UNIVERSITY AVENUE

SH

AT

TU

CK

A

VE

NU

E

Note: Location of BART right-of-way limitsestimated using the Record Map of Right ofWay, Berkeley-Richmond Line, Russell Streetto Grove Street, by Parsons Brinckerhoff TudorBectel Engineers, Package R-005, ContractK-501, Sheet RRW17, March 11, 1965

2012 BERKELEY WAY

A A'

A

A

'

SINGLE-STORYCOMMERCIAL

BUILDING

SINGLE-STORYCOMMERCIAL

BUILDING

SINGLE-STORYCOMMERCIAL

BUILDING

TWO-STORY

COMMERCIALBUILDING

THREE-STORYCOMMERCIAL

BUILDING

THREE-STORYCOMMERCIAL

BUILDING(NASH HOTEL)

TWO-STORYCOMMERCIAL

BUILDING

TWO-STORYRESIDENTIAL

BUILDING

TWO-STORYRESIDENTIAL

BUILDING

SINGLE-STORY STRUCTURE

TWO-STORYCOMMERCIAL

BUILDING

−−Depositional or intrusive contact, dashed where approximately located, dotted where concealed

−−Dashed where approximately located, small dashes where inferred, dotted where concealed, queried where location is uncertain.

−−Dotted where concealed

−−Shows fold axis, dotted where concealed

Contact - Depositional or intrusive contact, dashed where approximately located, dotted where concealed

Fault - Dashed where approximately located, small dashed where inferred, dotted where concealed, queried where locations is uncertainReverse or thrust fault - Dotted where concealed

Anticline -Shows fold axis, dotted where concealed

Syncline

Overturned bedding

Strike and dip of bedding

Flat beddingVertical beddingStrike and dip of foliationVertical foliation

Vertical jointStrike and dip of joints in plutonic rocks

0 4,000 Feet

Approximate scale

2,000

EXPLANATION af

Qhaf

Qhl

Qpaf

Tmb

KJfs

KJfm

Ku

Kfn

Kfgm

Jsv

sp

fg

Alluvial fan and fluvial deposits (Holocene)

Alluvial fan and fluvial deposits

Keratophyre and quartz keratophyre (Late Jurassic)

Sandstone of the Novato Quarry terrane ofBlake and others (1984) (Late Cretaceous)

Franciscan complex, melange (CretaceousLate Jurassic), includes mapped locally:

Chert blocks

Artificial fill (Historic)

Natural levee deposits (Holocene)

Morage Formation (late Miocene)

Franciscan complex, sandstone, undivided(Late Cretaceous to Late Jurassic)

Undivided Great Valley complex rocks(Cretaceous)

Fine-grained quartz deiorite (Late Cretaceous (?)

Greenstone blocks

Project No. FigureDate

SITE

4

REGIONAL GEOLOGIC MAP

Base map: USGS MF 2342, Geologic Map and Map Database of the Oakland Metropolitan Area, Alameda, Contra Costa, and San Francisco Counties, California (Graymer, 2000).

ROCKRIDGEGEOTECHNICAL 16-119311/21/16

2012 BERKELEY WAYBerkeley, California

Project No. FigureDate

Base Map: U.S. Geological Survey (USGS), National Seismic Hazards Maps - Fault Sources, 2008.

10 Miles

Approximate scale

0 5

5ROCKRIDGEGEOTECHNICAL

REGIONAL FAULT MAP

SITE

EXPLANATION

Strike slip

Thrust (Reverse)

Normal

16-119311/21/16

2012 BERKELEY WAYBerkeley, California

Point Reyes Fault

San Andreas FaultSan G

regorio Fault

Monte Vista-Shannon Fault

West N

apa

Mount Diablo Thrust

Greenville Fault

Great Valley 05

Great Valley 4b

Calaveras Fault

Green Valley

Hayward-Rodgers Creek Fault

Hayward-Rodgers Creek Fault

Project No. FigureDate 6

0 4,000 Feet

Approximate scale

2,000EXPLANATION

SITE

SEISMIC HAZARDS ZONE MAP

Earthquake-Induced Landslides; Areas where previous occurence of landslide movement, or local topographic, geological, geotechnical, and subsurface water conditions indicate a potential for permanent ground displacements.

Liquefaction; Areas where historic occurence of liquefaction, or local topographic, geological, geotechnical, and subsurfacewater conditions indicate a potential for permanent ground displacements.

Reference:State of California "Seismic Hazard Zones" Oakland West Quadrangle.Released on February 14, 2003

ROCKRIDGEGEOTECHNICAL 16-119311/21/16

2012 BERKELEY WAYBerkeley, California

APPENDIX A Logs of Borings

11213.950

S&H

S&H

S&H

S&H

S&H

S&H

S&H

CL

CL

CL

CL

CL

CL

CL

CL

CL

CL

3 inches of asphalt concrete9 inches of aggregate baseSANDY CLAY (CL)brown with light brown and red-brown, hard, moist,fine to medium sand

SANDY CLAY with GRAVEL (CL)brown with yellow and orange, hard, moist, finesand, angular fine gravelParticle Size Distribution; see Appendix B

SANDY CLAY (CL)brown, very stiff, moist

SANDY CLAY with GRAVEL (CL)brown mottled with red and yellow, very stiff, moist,subrounded fine gravel

CLAY (CL)brown with black staining, very stiff, moist, trace finesand

SANDY CLAY (CL)light brown, very stiff, moist, fine to medium sand

SANDY CLAY with GRAVEL (CL)brown, very stiff, moist, angular fine gravelSANDY CLAY (CL)light brown, very stiff, moist

CLAY with SAND (CL)brown mottled with olive and black staining, verystiff, moist, fine sand, trace coarse sand

SANDY CLAY (CL)brown mottled with olive and yellow, very stiff, moist,fine to coarse sand

32

45

22

22

27

22

17

141630

223034

131121

91219

71524

101319

7915

Sam

pler

Type

Sam

ple

Blo

ws/

6"

SP

TN

-Val

ue1

LITH

OLO

GY

DE

PTH

(feet

)

Dry

Den

sity

Lbs/

Cu

Ft

Type

of

Stre

ngth

Test

She

ar S

treng

thLb

s/S

q Ft

Fine

s%

Con

finin

gP

ress

ure

Lbs/

Sq

Ft

Nat

ural

Moi

stur

eC

onte

nt, %

See Site Plan, Figure 2

9/29/16

Hollow-Stem

Logged by:

Hammer type: Downhole Safety

Sprague & Henwood (S&H)

Date finished: 9/29/16

Hammer weight/drop: 140 lbs./30 inches

Sampler:

K. SamlikBoring location:

Date started:

Drilling method:

Approximate Ground Surface Elevation: 192.7 feet2

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

21

22

23

24

25

26

27

28

29

30

MATERIAL DESCRIPTION

LABORATORY TEST DATA

SAMPLES

Figure:A-1a

PROJECT:

Project No.:16-1193

2012 BERKELEY WAYBerkeley, California

PAGE 1 OF 2Log of Boring B-1

RO

CK

RID

GE

16-

1193

.GP

J T

R.G

DT

3/2

4/17

S&H

S&H

CL

CL

SANDY CLAY (CL) (continued)

SANDY CLAY with GRAVEL (CL)yellow-brown mottled with olive-brown, hard, moist,fine to medium sand

33

39

121928

162134

Dry

Den

sity

Lbs/

Cu

Ft

Type

of

Stre

ngth

Test

She

ar S

treng

thLb

s/S

q Ft

Fine

s%

Con

finin

gP

ress

ure

Lbs/

Sq

Ft

Nat

ural

Moi

stur

eC

onte

nt, %

Sam

pler

Type

Sam

ple

Blo

ws/

6"

SP

TN

-Val

ue1

LITH

OLO

GY

DE

PTH

(feet

)

31

32

33

34

35

36

37

38

39

40

41

42

43

44

45

46

47

48

49

50

51

52

53

54

55

56

57

58

59

60

MATERIAL DESCRIPTION

LABORATORY TEST DATASAMPLES

Figure:A-1b

PROJECT:

Project No.:16-1193

2012 BERKELEY WAYBerkeley, California

PAGE 2 OF 2Log of Boring B-1

RO

CK

RID

GE

16-

1193

.GP

J T

R.G

DT

3/2

4/17

Boring terminated at a depth of 40 feet below ground surface.Boring backfilled with cement grout.Groundwater not encountered during drilling.

1 S&H blow counts for the last two increments were convertedto SPT N-Values using a factor of 0.7 to account for samplertype and hammer energy.

2 Ground surface elevation estimated from TopographicsSurvey by Sandis, revised January 26, 2017. City of Berkeleydatum.

1071,800TxUU 21.84,300

S&H

S&H

S&H

S&H

S&H

S&H

S&H

SP

CL

SC

CL

CL

CL

CL

CL

4 inches of asphalt concreteSAND with GRAVEL (SP)light brown, medium dense, moist, angular finegravelSANDY CLAY (CL)dark brown, very stiff, moistCLAYEY SAND (SC)dark brown, medium dense, moist, fine sandSANDY CLAY (CL)brown, very stiff, moist, fine to medium sand, tracefine gravel

SANDY CLAY with GRAVEL (CL)brown mottled with yellow, hard, moist, angular finegravel, fine to coarse sand, trace rootlets

CLAY (CL)olive-brown and yellow with black staining, very stiff,moist

TxUU Test; see Appendix B

SANDY CLAY with GRAVEL (CL)olive-brown mottled with yellow, very stiff, moist,oxidized fine subrounded gravel, fine gravel-sizesandstone fragments

CLAY with SAND (CL)yellow-brown mottled with olive, very stiff to hard,moist, fine sand, trace subangular fine gravel

very stiff

27

22

67

28

20

30

18

151623

151516384550

81723

91117

41627

71213

Sam

pler

Type

Sam

ple

Blo

ws/

6"

SP

TN

-Val

ue1

LITH

OLO

GY

DE

PTH

(feet

)

Dry

Den

sity

Lbs/

Cu

Ft

Type

of

Stre

ngth

Test

She

ar S

treng

thLb

s/S

q Ft

Fine

s%

Con

finin

gP

ress

ure

Lbs/

Sq

Ft

Nat

ural

Moi

stur

eC

onte

nt, %

See Site Plan, Figure 2

9/29/16

Hollow-Stem

Logged by:

Hammer type: Downhole Safety

Sprague & Henwood (S&H)

Date finished: 9/29/16

Hammer weight/drop: 140 lbs./30 inches

Sampler:

K. SamlikBoring location:

Date started:

Drilling method:

Approximate Ground Surface Elevation: 192 feet2

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

21

22

23

24

25

26

27

28

29

30

MATERIAL DESCRIPTION

LABORATORY TEST DATA

SAMPLES

Figure:A-2a

PROJECT:

Project No.:16-1193

2012 BERKELEY WAYBerkeley, California

PAGE 1 OF 2Log of Boring B-2

RO

CK

RID

GE

16-

1193

.GP

J T

R.G

DT

3/2

4/17

S&H

S&H

CL

CL

CLAY with SAND (CL) (continued)

SANDY CLAY with GRAVEL (CL)yellow-brown mottled with olive and brown, hard,moist, subrounded fine gravel, fine to medium sand

yellow-brown mottled with olive, brown, and red

47

41

152740

111643

Dry

Den

sity

Lbs/

Cu

Ft

Type

of

Stre

ngth

Test

She

ar S

treng

thLb

s/S

q Ft

Fine

s%

Con

finin

gP

ress

ure

Lbs/

Sq

Ft

Nat

ural

Moi

stur

eC

onte

nt, %

Sam

pler

Type

Sam

ple

Blo

ws/

6"

SP

TN

-Val

ue1

LITH

OLO

GY

DE

PTH

(feet

)

31

32

33

34

35

36

37

38

39

40

41

42

43

44

45

46

47

48

49

50

51

52

53

54

55

56

57

58

59

60

MATERIAL DESCRIPTION

LABORATORY TEST DATASAMPLES

Figure:A-2b

PROJECT:

Project No.:16-1193

2012 BERKELEY WAYBerkeley, California

PAGE 2 OF 2Log of Boring B-2

RO

CK

RID

GE

16-

1193

.GP

J T

R.G

DT

3/2

4/17

Boring terminated at a depth of 40 feet below ground surface.Boring backfilled with cement grout.Groundwater not encountered during drilling.

1 S&H blow counts for the last two increments were convertedto SPT N-Values using a factor of 0.7 to account for samplertype and hammer energy.

2 Ground surface elevation estimated from TopographicsSurvey by Sandis, revised January 26, 2017. City of Berkeleydatum.

102

92

20.8

30.081

S&H

S&H

S&H

S&H

S&H

S&H

S&H

CL

CL

CL

CL

CL

4 inches of asphalt concrete8 inches of aggregate baseSANDY CLAY (CL)dark brown mottled with yellow, medium stiff, moist,fine to medium sandLL = 37, PI = 21; see Appendix B

SANDY CLAY with GRAVEL (CL)brown mottled with orange and black, very stiff,moist, fine sand, angular fine gravel

brown

subrounded fine gravel

SANDY CLAY (CL)light brown, stiff, moist, fine to medium sand, tracesubangular gravel

(2:30 PM; 9/29/16)

CLAY with SAND (CL)brown and olive, stiff to very stiff, wet, fine to coarsesandParticle Size Distribution; see Appendix BLL = 36, PI = 16; see Appendix Bolive-brown, fine to medium sand

SANDY CLAY (CL)yellow-brown, very stiff, wet, fine to medium sand,trace subrounded fine gravel

6

21

22

21

14

15

16

345

4822

111715

81317

6911

51011

6914

Sam

pler

Type

Sam

ple

Blo

ws/

6"

SP

TN

-Val

ue1

LITH

OLO

GY

DE

PTH

(feet

)

Dry

Den

sity

Lbs/

Cu

Ft

Type

of

Stre

ngth

Test

She

ar S

treng

thLb

s/S

q Ft

Fine

s%

Con

finin

gP

ress

ure

Lbs/

Sq

Ft

Nat

ural

Moi

stur

eC

onte

nt, %

See Site Plan, Figure 2

9/29/16

Hollow-Stem

Logged by:

Hammer type: Downhole Safety

Sprague & Henwood (S&H)

Date finished: 9/29/16

Hammer weight/drop: 140 lbs./30 inches

Sampler:

K. SamlikBoring location:

Date started:

Drilling method:

Approximate Ground Surface Elevation: 194 feet2

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

21

22

23

24

25

26

27

28

29

30

MATERIAL DESCRIPTION

LABORATORY TEST DATA

SAMPLES

Figure:A-3a

PROJECT:

Project No.:16-1193

2012 BERKELEY WAYBerkeley, California

PAGE 1 OF 2Log of Boring B-3

RO

CK

RID

GE

16-

1193

.GP

J T

R.G

DT

3/2

4/17

S&H

S&H

CL

CL

SANDY CLAY (CL) (continued)

SANDY CLAY with GRAVEL (CL)yellow mottled with olive and brown, hard, wet,subrounded fine gravel

33

36

141730

141735

Dry

Den

sity

Lbs/

Cu

Ft

Type

of

Stre

ngth

Test

She

ar S

treng

thLb

s/S

q Ft

Fine

s%

Con

finin

gP

ress

ure

Lbs/

Sq

Ft

Nat

ural

Moi

stur

eC

onte

nt, %

Sam

pler

Type

Sam

ple

Blo

ws/

6"

SP

TN

-Val

ue1

LITH

OLO

GY

DE

PTH

(feet

)

31

32

33

34

35

36

37

38

39

40

41

42

43

44

45

46

47

48

49

50

51

52

53

54

55

56

57

58

59

60

MATERIAL DESCRIPTION

LABORATORY TEST DATASAMPLES

Figure:A-3b

PROJECT:

Project No.:16-1193

2012 BERKELEY WAYBerkeley, California

PAGE 2 OF 2Log of Boring B-3

RO

CK

RID

GE

16-

1193

.GP

J T

R.G

DT

3/2

4/17

Boring terminated at a depth of 40 feet below ground surface.Boring backfilled with cement grout.Groundwater encountered at a depth of 21 feet after leavingthe boring open for about 3 hours.

1 S&H blow counts for the last two increments were convertedto SPT N-Values using a factor of 0.7 to account for samplertype and hammer energy.

2 Ground surface elevation estimated from TopographicsSurvey by Sandis, revised January 26, 2017. City of Berkeleydatum.

10016.6

45

S&H

S&H

S&H

S&H

S&H

S&H

S&H

SC

CL

CL

CL

SC

CL

3 to 4 inches of asphalt concrete9 inches of aggregate baseCLAYEY SAND with GRAVEL (SC)brown mottled with orange, medium dense, moist,fine to medium sand, trace angular fine gravelCorrosion Test; see Appendix BLL = 34, PI = 16; see Appendix B

dark brown mottled with yellow and red, subroundedfine gravelParticle Size Distribution; see Appendix B

SANDY CLAY with GRAVEL (CL)brown mottled with yellow and red, very stiff, moist,subangular fine gravel

CLAY (CL)brown mottled with olive, very stiff, moist

CLAY with SAND (CL)yellow-brown mottled with olive and orange, stiff tovery stiff, moist, fine sand, trace subrounded finegravel

CLAYEY SAND (SC)olive mottled with orange and brown, medium dense,moist, fine to medium sand

SANDY CLAY with GRAVEL (CL)yellow-brown mottled with olive and red, very stiff,moist, subrounded to angular fine gravel, fine tomedium sand

hard

13

25

18

29

15

28

36

10109

131619

101115

81625

7814

111822

171933

Sam

pler

Type

Sam

ple

Blo

ws/

6"

SP

TN

-Val

ue1

LITH

OLO

GY

DE

PTH

(feet

)

Dry

Den

sity

Lbs/

Cu

Ft

Type

of

Stre

ngth

Test

She

ar S

treng

thLb

s/S

q Ft

Fine

s%

Con

finin

gP

ress

ure

Lbs/

Sq

Ft

Nat

ural

Moi

stur

eC

onte

nt, %

See Site Plan, Figure 2

9/30/16

Hollow-Stem

Logged by:

Hammer type: Downhole Safety

Sprague & Henwood (S&H)

Date finished: 9/30/16

Hammer weight/drop: 140 lbs./30 inches

Sampler:

K. SamlikBoring location:

Date started:

Drilling method:

Approximate Ground Surface Elevation: 196.1 feet2

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

21

22

23

24

25

26

27

28

29

30

MATERIAL DESCRIPTION

LABORATORY TEST DATA

SAMPLES

Figure:A-4a

PROJECT:

Project No.:16-1193

2012 BERKELEY WAYBerkeley, California

PAGE 1 OF 2Log of Boring B-4

RO

CK

RID

GE

16-

1193

.GP

J T

R.G

DT

3/2

4/17

S&H

S&H

CL

SC

CL

SC

SANDY CLAY with GRAVEL (CL) (continued)

CLAYEY SAND (SC)light brown, very dense, moist, fine sand, tracegravel-sized sandstone fragments

SANDY CLAY (CL)dark brown and light brown, hard, moist, fine sand

(9/30/16)CLAYEY SAND (SC)brown, very dense, wet, fine to medium sand

60

35/5"

203550

50/5"

Dry

Den

sity

Lbs/

Cu

Ft

Type

of

Stre

ngth

Test

She

ar S

treng

thLb

s/S

q Ft

Fine

s%

Con

finin

gP

ress

ure

Lbs/

Sq

Ft

Nat

ural

Moi

stur

eC

onte

nt, %

Sam

pler

Type

Sam

ple

Blo

ws/

6"

SP

TN

-Val

ue1

LITH

OLO

GY

DE

PTH

(feet

)

31

32

33

34

35

36

37

38

39

40

41

42

43

44

45

46

47

48

49

50

51

52

53

54

55

56

57

58

59

60

MATERIAL DESCRIPTION

LABORATORY TEST DATASAMPLES

Figure:A-4b

PROJECT:

Project No.:16-1193

2012 BERKELEY WAYBerkeley, California

PAGE 2 OF 2Log of Boring B-4

RO

CK

RID

GE

16-

1193

.GP

J T

R.G

DT

3/2

4/17

Boring terminated at a depth of 39 feet below ground surface.Boring backfilled with cement grout.Groundwater encountered at a depth of 38 feet during drilling.

1 S&H blow counts for the last two increments were convertedto SPT N-Values using a factor of 0.7 to account for samplertype and hammer energy.

2 Ground surface elevation estimated from TopographicsSurvey by Sandis, revised January 26, 2017. City of Berkeleydatum.

991,800TxUU 26.63,450

S&H

S&H

S&H

S&H

S&H

S&H

S&H

S&H

CL

CL

CL

CL

CL

CL

3 inches of asphalt concrete9 inches of aggregate baseSANDY CLAY (CL)dark brown, medium stiff to stiff, fine sand, tracesubrounded fine gravel, trace rootletsSANDY CLAY with GRAVEL (CL)brown, very stiff, moist, fine to coarse sand, angularfine gravel

Corrosion Test; see Appendix Bbrown mottled with red and yellow, subangular finegravel

CLAY with SAND (CL)olive-brown mottled with yellow, very stiff, moist, finesandTxUU Test; see Appendix B

CLAY with SAND (CL)yellow-brown with red and black staining, very stiff,moist, fine sand, trace subangular fine gravel

SANDY CLAY (CL)yellow-brown mottled with olive, very stiff to hard,moist, fine to medium sand

SANDY CLAY with GRAVEL (CL)yellow-brown, hard, moist, fine to medium sand,subangular fine gravel

8

18

28

20

18

23

29

49

456

91016

101624

81217

71115

71320

51626

153040

Sam

pler

Type

Sam

ple

Blo

ws/

6"

SP

TN

-Val

ue1

LITH

OLO

GY

DE

PTH

(feet

)

Dry

Den

sity

Lbs/

Cu

Ft

Type

of

Stre

ngth

Test

She

ar S

treng

thLb

s/S

q Ft

Fine

s%

Con

finin

gP

ress

ure

Lbs/

Sq

Ft

Nat

ural

Moi

stur

eC

onte

nt, %

See Site Plan, Figure 2

9/30/16

Hollow-Stem

Logged by:

Hammer type: Downhole Safety

Sprague & Henwood (S&H), Standard Penetration Test (SPT)

Date finished: 9/30/16

Hammer weight/drop: 140 lbs./30 inches

Sampler:

K. SamlikBoring location:

Date started:

Drilling method:

Approximate Ground Surface Elevation: 194.1 feet2

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

21

22

23

24

25

26

27

28

29

30

MATERIAL DESCRIPTION

LABORATORY TEST DATA

SAMPLES

Figure:A-5a

PROJECT:

Project No.:16-1193

2012 BERKELEY WAYBerkeley, California

PAGE 1 OF 2Log of Boring B-5

RO

CK

RID

GE

16-

1193

.GP

J T

R.G

DT

3/2

4/17

S&H

S&H

SPT

SPT

SC

SC

CL

SANDY CLAY with GRAVEL (SC) (continued)

yellow-brown mottled with olive, brown and orange

(9/30/16)

CLAYEY SAND with GRAVEL (SC)yellow-brown mottled with olive and brown, verydense, wet, fine to medium sand, subangular finegravel

CLAY (CL)brown mottled with olive, hard, wet, trace fine sand

40

31

48

32

152433

101628

81624

101017

Dry

Den

sity

Lbs/

Cu

Ft

Type

of

Stre

ngth

Test

She

ar S

treng

thLb

s/S

q Ft

Fine

s%

Con

finin

gP

ress

ure

Lbs/

Sq

Ft

Nat

ural

Moi

stur

eC

onte

nt, %

Sam

pler

Type

Sam

ple

Blo

ws/

6"

SP

TN

-Val

ue1

LITH

OLO

GY

DE

PTH

(feet

)

31

32

33

34

35

36

37

38

39

40

41

42

43

44

45

46

47

48

49

50

51

52

53

54

55

56

57

58

59

60

MATERIAL DESCRIPTION

LABORATORY TEST DATASAMPLES

Figure:A-5b

PROJECT:

Project No.:16-1193

2012 BERKELEY WAYBerkeley, California

PAGE 2 OF 2Log of Boring B-5

RO

CK

RID

GE

16-

1193

.GP

J T

R.G

DT

3/2

4/17

Boring terminated at a depth of 50 feet below ground surface.Boring backfilled with cement grout.Groundwater encountered at a depth of 43 feet during drilling.

1 S&H and SPT blow counts for the last two increments wereconverted to SPT N-Values using factors of 0.7 and 1.2,respectively, to account for sampler type and hammerenergy. SPT sampler used without liners.

2 Ground surface elevation estimated from TopographicsSurvey by Sandis, revised January 26, 2017. City of Berkeleydatum.

CLASSIFICATION CHART

Major Divisions Symbols Typical Names

GW

GP

GM

GC

SW

SP

SM

SC

ML

CL

OL

MH

CH

OH

PTHighly Organic Soils

UNIFIED SOIL CLASSIFICATION SYSTEM

Well-graded gravels or gravel-sand mixtures, little or no fines

Poorly-graded gravels or gravel-sand mixtures, little or no fines

Silty gravels, gravel-sand-silt mixtures

Clayey gravels, gravel-sand-clay mixtures

Well-graded sands or gravelly sands, little or no fines

Poorly-graded sands or gravelly sands, little or no fines

Silty sands, sand-silt mixtures

Inorganic silts and clayey silts of low plasticity, sandy silts, gravelly silts

Inorganic clays of low to medium plasticity, gravelly clays, sandy clays, lean clays

Organic silts and organic silt-clays of low plasticity

Inorganic silts of high plasticity

Inorganic clays of high plasticity, fat clays

Organic silts and clays of high plasticity

Peat and other highly organic soils

Clayey sands, sand-clay mixtures

Range of Grain SizesGrain Size

in MillimetersU.S. Standard

Sieve SizeAbove 12"

12" to 3"

Classification

Boulders

Cobbles

Above 305

305 to 76.2

Silt and Clay Below No. 200 Below 0.075

GRAIN SIZE CHART

SAMPLER TYPE

Coa

rse-

Gra

ined

Soi

ls(m

ore

than

hal

f of s

oil >

no.

200

siev

e si

ze)

Fine

-Gra

ined

Soi

ls(m

ore

than

hal

f of s

oil

< no

. 200

sie

ve s

ize)

Gravels(More than half ofcoarse fraction >no. 4 sieve size)

Sands(More than half ofcoarse fraction <no. 4 sieve size)

Silts and ClaysLL = < 50

Silts and ClaysLL = > 50

Gravel coarse fine

3" to No. 43" to 3/4"

3/4" to No. 4

No. 4 to No. 200No. 4 to No. 10No. 10 to No. 40No. 40 to No. 200

76.2 to 4.7676.2 to 19.119.1 to 4.76

4.76 to 0.0754.76 to 2.002.00 to 0.4200.420 to 0.075

Sand coarse medium fine

C Core barrel

CA California split-barrel sampler with 2.5-inch outside diameter and a 1.93-inch inside diameter

D&M Dames & Moore piston sampler using 2.5-inch outside diameter, thin-walled tube

O Osterberg piston sampler using 3.0-inch outside diameter, thin-walled Shelby tube

PT Pitcher tube sampler using 3.0-inch outside diameter, thin-walled Shelby tube

S&H Sprague & Henwood split-barrel sampler with a 3.0-inch outside diameter and a 2.43-inch inside diameter

SPT Standard Penetration Test (SPT) split-barrel sampler with a 2.0-inch outside diameter and a 1.5-inch inside diameter

ST Shelby Tube (3.0-inch outside diameter, thin-walled tube) advanced with hydraulic pressure

SAMPLE DESIGNATIONS/SYMBOLS

Sample taken with Sprague & Henwood split-barrel sampler with a 3.0-inch outside diameter and a 2.43-inch inside diameter. Darkened area indicates soil recovered

Classification sample taken with Standard Penetration Test sampler

Undisturbed sample taken with thin-walled tube

Disturbed sample

Sampling attempted with no recovery

Core sample

Analytical laboratory sample

Sample taken with Direct Push sampler

Sonic

Unstabilized groundwater level

Stabilized groundwater level

ROCKRIDGEGEOTECHNICAL Project No. Figure A-6Date 16-119311/21/16

2012 BERKELEY WAYBerkeley, California

APPENDIX B Laboratory Test Results

ML or OL

MH or OH

Symbol SourceNatural

M.C. (%)Liquid

Limit (%)

CL - ML

0

10

20

30

40

50

60

70

0 10 20 30 40 50 60 70 80 90 100 110 120LIQUID LIMIT (LL)

Description and Classification% Passing#200 Sieve

PlasticityIndex (%)

PLASTICITY CHART

ROCKRIDGEGEOTECHNICAL Project No. FigureDate B-116-119311/21/16

2012 BERKELEY WAYBerkeley, California

PLA

STI

CIT

Y IN

DE

X (P

I)Ref erence:ASTM D2487-00

B-3 at 24 feet

B-3 at 2.0 feet

B-4 at 1.5 feet

CLAY with SAND (CL), brown and olive

SANDY CLAY (CL), dark brown mottledwith yellow

CLAYEY SAND with GRAVEL (SC),brown mottled with orange

30.0

20.8

16.6

81

--

--

35

37

34

16

21

16

SYMBOL SOURCE DEPTH Material Description USCS(ft.)

MATERIAL DATA

PE

RC

EN

T FI

NE

R

0

10

20

30

40

50

60

70

80

90

100

GRAIN SIZE - mm.

0.0010.010.1110100

% +3"Coarse

% GravelFine Coarse Medium

% SandFine Silt

% FinesClay

6 in

.

3 in

.

2 in

.1½

in.

1 in

.¾

in.

½ in

.3/

8 in

.

#4 #10

#20

#30

#40

#60

#100

#140

#200

B-1 5.5'

B-3

B-4 6.0'

PARTICLE SIZE DISTRIBUTION REPORT

ROCKRIDGEGEOTECHNICAL

SANDY CLAY with GRAVEL, brown with yellow and orange

CLAY with SAND, brown and olive

CLAYEY SAND with GRAVEL, brown mottled with orange

Project No. FigureDate B-216-1193

24.0’

CL

CL

SC

11/21/16

2012 BERKELEY WAYBerkeley, California

0

1,000

2,000

3,000

4,000

5,000

6,000

7,000

8,000

9,000

10,000

0 5 10 15 20 25

Project No. FigureDate B-3

UNCONSOLIDATED-UNDRAINEDTRIAXIAL COMPRESSION TEST

ROCKRIDGEGEOTECHNICAL

B-2 at 14.5 feetCLAY (CL), olive-brown

2.40 5.65

21.8

107

4,300

20.0

1,800

1

SAMPLER TYPE

DIAMETER (in.)

MOISTURE CONTENT

DRY DENSITY

DESCRIPTION

SHEAR STRENGTH

STRAIN AT FAILURE

CONFINING PRESSURE

STRAIN RATE

HEIGHT (in.)

SOURCE

%

pcf

psf

%psf

% / min.

AXIAL STRAIN (percent)

Sprague and Henwood

DE

VIA

TOR

STR

ES

S (p

sf)

16-119311/21/16

2012 BERKELEY WAYBerkeley, California

0

1,000

2,000

3,000

4,000

5,000

6,000

7,000

8,000

0 5 10 15 20 25

Project No. FigureDate B-4

UNCONSOLIDATED-UNDRAINEDTRIAXIAL COMPRESSION TEST

ROCKRIDGEGEOTECHNICAL

B-5 at 14.5 feetCLAY with SAND (CL), olive-brown mottled with yellow

2.39 5.98

26.6

99

3,450

17.9

1,800

1

SAMPLER TYPE

DIAMETER (in.)

MOISTURE CONTENT

DRY DENSITY

DESCRIPTION

SHEAR STRENGTH

STRAIN AT FAILURE

CONFINING PRESSURE

STRAIN RATE

HEIGHT (in.)

SOURCE

%

pcf

psf

%psf

% / min.

AXIAL STRAIN (percent)

Sprague and Henwood

DE

VIA

TOR

STR

ES

S (p

sf)

16-119311/21/16

2012 BERKELEY WAYBerkeley, California