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GEOTECHNICAL FEASIBILITY REPORT

HIGH RISE AT THE SHATTUCK BERKELEY, CALIFORNIA

Submitted to: Ms. Gretchen Barth

Hill Street Realty 11100 Santa Monica Boulevard, Suite 880

Los Angeles, CA 90025

Prepared by: ENGEO Incorporated

January 25, 2013

Project No:

9842.000.000

Copyright © 2013 by ENGEO Incorporated. This document may not be reproduced in whole or in part by any means whatsoever, nor may it be quoted or excerpted without the express written consent of ENGEO Incorporated.

GEOTECHNICAL ENVIRONMENTAL

WATER RESOURCES CONSTRUCTION SERVICES

2010 Crow Canyon Place, Suite 250 San Ramon, CA 94583 (925) 866-9000 Fax (888) 279-2698 www.engeo.com

Project No. 9842.000.000

January 25, 2013 Ms. Gretchen Barth Hill Street Realty 11100 Santa Monica Boulevard, Suite 880 Los Angeles, CA 90025 Subject: High Rise at The Shattuck Berkeley, California GEOTECHNICAL FEASIBILITY REPORT Dear Ms. Barth: ENGEO prepared this geotechnical feasibility report for the proposed high-rise development adjacent to The Shattuck Hotel in downtown Berkeley, California, as outlined in our agreement dated November 14, 2012. We characterized the subsurface conditions at the site to provide the preliminary feasibility study. The accompanying report contains our data review, conclusions, and preliminary recommendations for the geotechnical aspects of the proposed development on the subject site. Based on our study, it is our opinion that the proposed development is feasible from a geotechnical standpoint provided the preliminary recommendations included in this report are followed. We are pleased to be of service to you on this project and look forward to consulting further with you and your design team. Sincerely, ENGEO Incorporated Pedro Espinosa, GE R. William Rudolph, GE

Hill Street Realty 9842.000.000 High Rise at The Shattuck January 25, 2013

TABLE OF CONTENTS Letter of Transmittal

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

1.1 PURPOSE AND SCOPE .......................................................................................1 1.2 PROJECT LOCATION ........................................................................................1 1.3 PROJECT DESCRIPTION ..................................................................................2

2.0 FINDINGS ...................................................................................................... 2

2.1 GEOLOGY AND SEISMICITY ..........................................................................2 2.1.1 Regional Geology ........................................................................................2 2.1.2 Local Geology ..............................................................................................2 2.1.3 Seismicity .....................................................................................................3

2.2 REVIEW OF EXISTING DATA .........................................................................3 2.3 SUBSURFACE CONDITIONS ............................................................................3 2.4 GROUNDWATER CONDITIONS ......................................................................4

3.0 CONCLUSIONS ............................................................................................ 4

3.1 IMPLEMENTATION OF CBC 2013 ..................................................................4 3.2 SEISMIC HAZARDS ............................................................................................5

3.2.1 Ground Rupture ...........................................................................................5 3.2.2 Ground Shaking ...........................................................................................5 3.2.3 Liquefaction .................................................................................................5 3.2.4 Lateral Spreading .........................................................................................6

3.3 2010 AND 2013 CBC SEISMIC DESIGN PARAMETERS ..............................6 3.4 SOIL CORROSION POTENTIAL ......................................................................7 3.5 EXCAVATION ......................................................................................................7

4.0 PRELIMINARY SITE RECOMMENDATIONS ...................................... 7

4.1 DEMOLITION AND SITE CLEARING ............................................................7

5.0 PRELIMINARY FOUNDATION RECOMMENDATIONS .................... 8

5.1 MAT FOUNDATION ............................................................................................8 5.1.1 Uplift Loads .................................................................................................8

5.2 WATERPROOFING .............................................................................................9

6.0 PRELIMINARY BASEMENT WALLS ...................................................... 9

6.1 LATERAL SOIL PRESSURES ...........................................................................9 6.2 SEISMIC DESIGN CONSIDERATIONS ...........................................................9

7.0 EXCAVATION DEWATERING, SHORING AND UNDERPINNING ... 9

7.1 CONSTRUCTION DEWATERING ..................................................................10 7.2 TEMPORARY SHORING .................................................................................10


TABLE OF CONTENTS (Continued)

7.3 UNDERPINNING ................................................................................................10 7.4 PRE-CONSTRUCTION SURVEY AND CONSTRUCTION

MONITORING ....................................................................................................10 7.5 ADDITIONAL RECOMMENDATIONS ..........................................................11

8.0 LIMITATIONS AND UNIFORMITY OF CONDITIONS ...................... 11

FIGURES Figure 1 – Vicinity Map Figure 2 – Site Plan Figure 3 – Geologic Map Figure 4 – Geologic Map Figure 5 – Regional Faulting and Seismicity Map Figure 6 – Seismic Hazards Map Figure 7 – Historical Alignment of Strawberry Creek

APPENDIX A – PSH Deaggregation


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1.0 INTRODUCTION 1.1 PURPOSE AND SCOPE ENGEO prepared this geotechnical feasibility report for the proposed high-rise development adjacent to The Shattuck Hotel in downtown Berkeley, California. We prepared this report as outlined in our agreement dated November 14, 2012. Hill Street Realty authorized ENGEO to conduct the proposed scope of services, which included the following: • Site visit and review of available subsurface geotechnical and environmental data from the

site and adjacent to the site, review of published geologic maps and pre-development historical maps.

• Contact the City of Berkeley to request any available information regarding the construction of the culvert adjacent to the site and any existing geotechnical data in the area.

• Seismic design criteria in accordance with the 2010 CBC and 2013 CBC (ASCE 7-10

methodology), preliminary qualitative evaluation of liquefaction and other seismic hazards.

• Preliminary foundation design alternatives, including shallow mat/footing foundations, and deep foundations to control settlements and resist vertical compression/uplift, as well as lateral loads.

• Design consideration for basements including anticipated groundwater conditions,

excavation shoring, construction dewatering, and permanent under-drainage or hydrostatic uplift requirements.

• Preparation of a report providing our preliminary findings and conclusions regarding the

geotechnical aspects of the project. This report was prepared for the exclusive use of our client and their consultants for design of this project. In the event that any changes are made in the character, design or layout of the development, we must be contacted to review the conclusions and recommendations contained in this report to determine whether modifications are necessary. This document may not be reproduced in whole or in part by any means whatsoever, nor may it be quoted or excerpted without our express written consent. 1.2 PROJECT LOCATION The site is located on the block bounded by Shattuck Avenue to the east, Allston Way to the north, Harold Way to the west and Kittredge Street to the south. in Berkeley, California (Figure 1). The site is generally flat and consists approximately 1.50 acres. The site is currently occupied by 1- to 3-story buildings on the western side of the block, and 1- to 6-story buildings


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on the eastern and northern ends of the block. The eastern and northern end of the block (facing Shattuck Ave and Allston Way) are part of the historical Shattuck Hotel. 1.3 PROJECT DESCRIPTION Based on the preliminary renderings from MVEI Architects dated October 26, 2012, two schemes are proposed for the western half of the block bounded by Shattuck Avenue to the east, Allston Way to the north, Harold Way to the west and Kittredge Street to the south. The historical buildings on the eastern side of the block will remain under both schemes. Scheme A depicts “twin” 18-story towers facing Harold Way, while Scheme B depicts one 18-story and one 12-story towers facing Harold way with an additional 12-story tower facing Kittredge Street (single “L” tower). Both schemes are proposed to have as many as four levels of basement for underground garage stalls. The excavation for the four levels of basement will be in relative close proximity to the existing historical buildings. 2.0 FINDINGS 2.1 GEOLOGY AND SEISMICITY 2.1.1 Regional Geology The site is located in the Northern California Coast Ranges geomorphic province, which is dominated by northwest-trending faults and folds. The Coast Ranges are a complex series of linear mountain ranges that lie more-or-less parallel to the coast and to the San Andreas Fault System. The Coast Ranges are composed primarily of Jurassic and Cretaceous-age rocks that accumulated on the sea floor and were later scraped-off when the ocean plate on which they originated was subducted beneath North America. These older rocks include a tectonic mix of sandstone, chert, altered basalt referred to as greenstone, and serpentinite, collectively referred to as the Franciscan Complex. While Franciscan bedrock is exposed in the hills and cliffs of the San Francisco Bay Area, the flanks of the hills are blanketed with thin to thick layers of colluvium and alluvium (weathered material washed downslope from the bedrock exposures). Valleys are filled with water-laid stream deposits. 2.1.2 Local Geology The site geology has been mapped by Radbruch (1957) and updated by Seismic Hazard Zone for the Oakland West Quadrangle (California Geological Survey, 2003) (Figures 3 and 4). The geologic unit mapped at the site by Radbruch is described as the Quaternary Temescal formation, which is comprised of alluvial-fan deposits with interfingering lenses of clayey gravel, sandy silty clay, and sand-clay-silt mixtures. The CGS (2003) maps the site as having surficial soils of the Quaternary Holocene alluvial fan deposits, artificial fills related to the historic alignment of the south fork of the Strawberry Creek, and deeper soils of the older Quaternary Pleistocene alluvial fan deposits.


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2.1.3 Seismicity No active faults are known to pass through the site based on a review of the most recent compilation of Quaternary-active faults by the USGS (Graymer, et al., 2006). According to the USGS interactive deaggregation tool, most of the seismic risk for a probability of 2% in 50 years comes from the Hayward fault, which is, situated less than 2 miles away from our site. This seismic event has a moment magnitude of 7.0. The deaggregation output is shown in Appendix A. Many earthquakes of low magnitude occur every year throughout the region; most are concentrated along the San Andreas, Hayward and Calaveras faults. Figure 5 shows the approximate location of Quaternary faults and significant historic earthquakes mapped within the San Francisco Bay Region. Active faults in the San Francisco Bay Area capable of producing significant ground shaking at the Site are shown in Figure 5. Any one of these faults could generate an earthquake capable of causing strong ground shaking at the site. Earthquakes of Magnitude 7 and larger have historically occurred in the Bay Area and numerous small magnitude earthquakes occur every year; therefore, the site will likely experience moderate to strong ground shaking from an earthquake within the design life of the project. 2.2 REVIEW OF EXISTING DATA As part of our scope for this feasibility report, we reviewed relevant information regarding geotechnical and geological aspects of the site. We reviewed the following reports: • Soils Investigation Segment R-005, Berkeley, California by Dames and Moore (1965) in

support of the design of the Bay Area Rapid Transit district tunnel below Shattuck Avenue.

• Geotechnical Exploration, Berkeley High School, Berkeley, California, ENGEO Incorporated, October 22, 2008.

• Geotechnical Study, Brower Center, Berkeley, California, Fugro West, Inc; February 23, 2005.

• Geotechnical Engineering Study, University of California, Berkeley, Art Museum Relocation Study, Berkeley, California; URS; May 8, 2001.

2.3 SUBSURFACE CONDITIONS Review of available test boring data in the area generally confirms the conditions shown of the referenced geologic and historical maps. Surface soils at the site generally consists of stiff to very stiff gravelly to sandy clayey with interbedded layers of medium dense to dense clayey sand and gravels sized rock fragments. These are interpreted as Holocene age alluvial fan deposits and generally extend to depths less than 20 feet deep. The younger alluvium is underlain by older


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Pleistocene alluvium, generally consisting of similar layers of interbedded clays, sands and gravels. However, the older granular deposits are dense to very dense and the clayey soils are very stiff to hard. As shown on Figure 7, the historical alignment of the Strawberry Creek was incised into the alluvium through the northern side of the project site. At the end of the 1800’s the creek was re-aligned within a culvert below Allston Way. Geologic maps (Figure 4) show this historical alignment as being filled with artificial fill. This type of historical creek fill is common within the Berkeley area. Generally, the historic creeks contain up to 10 feet of native creek deposits consisting of loose to medium dense sand and medium stiff to stiff clays. Typically relatively poor quality fill was placed in the historic creek alignments. As a result, the fill may contain weak and compressible soils, debris and/or loose liquefiable soils. The total thickness of the fill and creek deposits generally is less than 20 to 25 feet. 2.4 GROUNDWATER CONDITIONS During our review of existing data, we found that groundwater levels at the site may range from 15 to 20 feet below ground surface. Fluctuations in groundwater levels may occur daily, seasonally and over a period of years because of precipitation and other factors, including the water levels in the adjacent creeks/culverts. The potential for groundwater contamination could be a construction consideration as described below. 3.0 CONCLUSIONS Based on our knowledge of the area and our review of existing data, we conclude that the proposed development is feasible from a geotechnical standpoint, provided that the preliminary recommendations included in this report, along with other sound engineering practices, are incorporated in the design and construction of the project. The primary geotechnical considerations for this project are: • The presence of adjacent structures and roadways to the proposed excavation and the need

for shoring and possibly underpinning. • The presence of groundwater within 15 feet of the existing ground surface and its influence

on below grade construction.

• The presence of potentially liquefiable sands locally below the proposed excavation. • Selection of an appropriate foundation system.

3.1 IMPLEMENTATION OF CBC 2013 We understand that the building may be designed under the future California Building Code to be published in 2013. This new building code will be based on the “Minimum Design Loads for


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Buildings and Other Structures: ASCE Standard 7-10.” Some of the major geotechnical changes that may result due to the implementation of the new code are the following: • Use of the Maximum Credible Earthquake peak ground acceleration (PGA) for calculation of

geohazards. These geohazards are, but not limited to liquefaction potential, pseudo-static slope stability and horizontal seismic loading on walls.

• Increase in seismic design parameter values to calculate seismic forces on the superstructure.

This increase is due to the fact that new code is moving away from a uniform hazard to determine seismic force to a “target risk of structural collapse.”

• Additional increases in the seismic forces are due to the adjustment of the ground motions to

model the behavior of the maximum response instead of the geometric mean response. 3.2 SEISMIC HAZARDS Potential seismic hazards resulting from a nearby moderate to major earthquake can generally be classified as primary and secondary. The primary effect is ground rupture, also called surface faulting. The common secondary seismic hazards include ground shaking, and ground lurching. The following sections present a discussion of these hazards as they apply to the site. 3.2.1 Ground Rupture Since there are no known active faults crossing the property and the site is not located within an Earthquake Fault Special Study Zone, it is our opinion that ground rupture is unlikely at the subject property. 3.2.2 Ground Shaking An earthquake of moderate to high magnitude generated within the San Francisco Bay Region could cause considerable ground shaking at the site, similar to that which has occurred in the past. To mitigate the shaking effects, all structures should be designed using sound engineering judgment and the latest California Building Code (CBC) requirements, as a minimum. 3.2.3 Liquefaction Soil liquefaction results from loss of strength during cyclic loading, such as imposed by earthquakes. Soils most susceptible to liquefaction are clean, loose, saturated, uniformly graded, fine-grained sands. The basis of the 2013 CBC is the ASCE 7-10, and this publication no longer uses a “design” PGA derived from the design response spectrum but specifies an “ultimate” value of the PGA derived from the Maximum Credible Earthquake (MCE). This will increase the input motions to calculate triggering of liquefaction.


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From our review of existing data, it appears that the native soils are too dense to be prone to liquefaction. However, the historical alignment of the Strawberry Creek was backfilled with uncontrolled fill (see Section 2.3) which has been mapped as potentially liquefiable by the California Geological Survey (Figure 6). As stated above, part of this historical alignment runs underneath the northern end of the project site. From the description of the proposed building, we understand that up to 4 basement levels are considered for the project. It is our opinion that excavation for the construction of the 4 basement levels will remove the backfill used to fill in the Strawberry Creek as well as the potentially weak or liquefiable recent creek deposits at the site. Considering that a site specific geotechnical exploration is recommended to confirm this, it is our opinion that the potential for liquefaction at the site is negligible. 3.2.4 Lateral Spreading Lateral spread is the finite, lateral displacement of sloping ground (0.1 to <6 percent) as a result of pore pressure buildup or liquefaction in a shallow, underlying soil deposit during an earthquake. Lateral spreading, as a result of liquefaction, occurs when a soil mass slides laterally on a liquefied layer, and gravitational and inertial forces cause the layer, and the overlying non-liquefied material, to move in a downslope direction. The magnitude of lateral spreading movements depends on earthquake magnitude, distance between the site and the seismic event, thickness of the liquefied layer, ground slope or ratio of free-face height to distance between the free face and structure, fines content, average particle size of the materials comprising the liquefied layer, and the standard penetration rates of the materials. As stated in the previous section the liquefaction potential under this preliminary evaluation was deemed to be negligible, therefore lateral spread potential at the building site is also considered low. 3.3 2010 AND 2013 CBC SEISMIC DESIGN PARAMETERS We provide the 2010 and 2013 California Building Code (CBC) seismic parameters in Table 3.3-1 for your use and comparison. We classified this site as Site Class D.

TABLE 3.3-1 2010 and 2013 CBC Seismic Design Parameters

Parameter Design Value 2010 CBC

Design Value 2013 CBC

Site Class D D

0.2 second Spectral Response Acceleration, SS 1.93 2.33

1.0 second Spectral Response Acceleration, S1 0.74 0.97

Site Coefficient, FA 1.0 1.0

Site Coefficient, FV 1.5 1.5 Maximum considered earthquake spectral response accelerations for short periods, SMS

1.93 2.33


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Parameter Design Value 2010 CBC

Design Value 2013 CBC

Maximum considered earthquake spectral response accelerations for 1-second periods, SMS

1.11 1.45

Design spectral response acceleration at short periods, SDS 1.29 1.55

Design spectral response acceleration at 1-second periods, SD1 0.74 0.97

Long period transition-period, TL 8 seconds 8 seconds If necessary, development of a site-specific spectrally matched time-histories may be develop in conjunction with non-linear structural analyses by the structural designer. 3.4 SOIL CORROSION POTENTIAL Based on sulfate testing done at nearby sites, the native soils are classified within the negligible sulfate exposure levels. Site specific corrosivity testing should be performed to determine corrosion levels for concrete and steel. A corrosion specialist should be consulted for corrosivity design and protection. 3.5 EXCAVATION As discussed previously, an excavation upwards of 40 feet deep may be necessary for the construction of the proposed basement levels. During excavation of the basement, the sides of the excavation should be shored, and support of adjacent settlement sensitive structures such as the adjacent historical buildings should be addressed in the design of temporary construction support. The primary considerations related to the selection of the shoring systems are: • The probable presence of shallow groundwater at approximately 15 feet below the existing

ground surface;

• Relative closeness of historical structures around the future excavation.

4.0 PRELIMINARY SITE RECOMMENDATIONS 4.1 DEMOLITION AND SITE CLEARING After demolition of the existing buildings on the western side of the bock, the site should be cleared of all obstructions, including existing foundations, and debris that are not cleared by the excavation of the proposed parking garage. Any existing underground utilities at the site should be identified and either properly abandoned or relocated. Holes resulting from the removal of underground obstructions extending below the proposed finish grades should be cleared and backfilled with suitable properly compacted fill. If the existing buildings within the footprint of the proposed buildings are founded on deep foundations, these elements should be removed down to at least 5 feet below bottom of proposed building slab.


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5.0 PRELIMINARY FOUNDATION RECOMMENDATIONS Based on our review of existing data as described in Section 2 of this report, it is our opinion that the vertical static loads of the structure can be supported utilizing a structural mat foundation. Generally, a mat foundation will help bridge areas of localized settlement and help resist hydrostatic uplift pressures. Additionally, the high seismic loading expected due to the nearby Hayward Fault, may require deep vertical foundation members to withstand uplift and tension forces due to the “rocking” of the superstructure. 5.1 MAT FOUNDATION For preliminary cost estimating, a modulus of subgrade reaction of 150 pounds per square inch (psi) per inch of deflection for the native soils can be used. A lateral friction coefficient of 0.35 between the bottom of the mat and the soil can be used for design. The mat foundation design should be sufficiently stiff to act as a rigid unit with minimum differential movement. Due to the very stiff/dense nature of the native soils, and excavation of up to 4 basement levels, the static settlement of the foundation elements will be negligible after the building has been constructed. This will be confirmed during the site specific geotechnical exploration. 5.1.1 Uplift Loads We anticipate that the garage will be below the groundwater level and will have to be designed for hydrostatic uplift loads. Uplift resistance can be provided by the weight of the foundation elements and the dead loads of the building. As previously discussed, high tension or uplift forces may develop at the foundation level during the design seismic event due to high horizontal forces the superstructure will see. These forces may be by deep vertical or battered foundation elements. The deep foundation elements can be cast-in-place-drilled-holes (CIDH) piles, micropiles, or anchors. These can be designed as active or passive systems and we can provide more details as necessary. If an active system is selected additional vertical loading on the mat and vertical settlement can be expected. The relatively shallow depth of the groundwater may cause difficulties with CIDH and micropile construction. Depending on the structural seismic design, some of the horizontal forces that produce the rocking motion and uplift loads, may be resisted by ultimate passive resistance of the soils on the basement walls.


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5.2 WATERPROOFING We recommend that for preliminary cost estimating, groundwater levels for the project are assumed to be at about 15 feet below existing grade. Permanent dewatering is not recommended and the concrete slabs and walls for the basements will have to be waterproofed and designed to resist hydrostatic and/or uplift pressures. The waterproofing should be designed by a consultant that specializes in permanent waterproofing construction. 6.0 PRELIMINARY BASEMENT WALLS 6.1 LATERAL SOIL PRESSURES The garage basement walls will act as retaining walls. Basement walls should be designed for at-rest lateral loading conditions. For cost estimating, we recommend the following lateral equivalent fluid pressures (static case):

TABLE 6.1-1 Lateral Earth Pressures

Loading Condition Equivalent Fluid Pressures (Pcf)

Without Hydrostatic Pressures (pcf)

With Hydrostatic Pressures (pcf)

Restrained (At-Rest) 65 95 The design groundwater level should be assumed to be located at 15 feet below finished exterior grade. The parking garage walls that will be constructed below the design groundwater elevation should be waterproofed and designed to resist hydrostatic pressures acting on the entire wall height. Evaluation of passive resistances should be done accordingly with the structural design needs. Ultimate and allowable values passive resistance can be determined in conjunction with the structural designer. 6.2 SEISMIC DESIGN CONSIDERATIONS Seismic conditions need to be considered in the design of the garage basement retaining walls. Under seismic conditions, the active incremental seismic force along the face of a retaining wall should be added to the static active pressures. The amount of the increment is a function of the PGA at the site, and as discussed in Section 3.1, additional analyses may be required. 7.0 EXCAVATION DEWATERING, SHORING AND UNDERPINNING Excavation, dewatering and shoring are temporary works that are typically the responsibility of the contractor to design, install, maintain and monitor. The following sections provide preliminary considerations that should be incorporated into the cost estimating process. Geotechnical shoring design recommendations are dependent on performance criteria, the type of


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system selected and construction sequencing. Accordingly, detailed recommendation should be made in collaboration with the shoring and dewatering designers. 7.1 CONSTRUCTION DEWATERING It is anticipated that dewatering will be accomplished using interior well points that collect groundwater and discharge the water to an appropriate discharge facility. The water level should be maintained at least 3 feet below the bottom of the deepest excavation during construction. The selection of equipment, actual depth and spacing of the wells should be determined by the dewatering designer/contractor. The dewatering system implemented should be selected so as to have minimal impact on the groundwater level surrounding the proposed excavation. Environmental concerns regarding dewatering should be taken into account by the environmental consultant. 7.2 TEMPORARY SHORING Temporary shoring will be required to facilitate site construction. Shoring design pressures and construction sequence should be selected to limit horizontal and vertical ground deformations due to shoring deflection. Types of shoring to be considered by the design team may be but are not limited to: soil nail walls and soldier pile and lagging with tie-backs. Given the proposed excavation depth, it will likely be necessary to restrain the shoring by using a single-level or multi-level system of tie-back anchors or to provide internal bracing. Prior to tie-back design and construction, permission from the neighboring properties will have to be obtained if tie-backs are to encroach into those adjacent properties. Tie-back anchors may be installed to avoid adjacent underground utilities. 7.3 UNDERPINNING The excavation for the proposed basement will extend below adjacent foundations and underpinning may be required. Foundation details for the adjacent structures are unknown; however, from our experience, the likelihood that adjacent buildings have shallow foundation systems is high. This will need to be confirmed with test pit excavations, if underpinning is deemed to be necessary. 7.4 PRE-CONSTRUCTION SURVEY AND CONSTRUCTION MONITORING Excavation dewatering and construction will take place adjacent to existing structures, roadways and underground utilities. We recommend that a pre-construction survey (e.g. crack survey) and monitoring program for the surrounding culverts, buildings, roadways, utilities, etc. which may be affected by construction activities be performed before and during construction. This will form a basis for any damage claims and also assist the contractor in assessing the performance of the shoring or excavation slopes. The pre-construction survey should record the elevation and horizontal position of all existing installations within 50 feet minimum and may consist of photographs, video tapes, topographic survey, etc.


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It is recommended that a system of construction monitoring is installed. This may consist of inclinometers and groundwater monitoring wells that are installed within a distance of 5 to 15 feet from the excavation towards the existing buildings. Vibration monitoring should be considered during operations of heavy equipment such as pile driving, demolition, etc. In addition, a settlement survey should initially be performed on a weekly basis during excavation and on a monthly basis, approximately one month after the excavation has been completed, at a minimum. 7.5 ADDITIONAL RECOMMENDATIONS Based upon our findings and assuming that the project proceeds into the next phase of development, additional geotechnical studies will be necessary. These studies will include: • A design-level geotechnical exploration which may entail groundwater piezometers and

exploratory borings, as appropriate. • A review of final construction plans and specifications, including grading plans, foundation

plans and calculations for conformance with our recommendations. Although these studies are not included in our scope of work, we believe that they are important in expediting approval by governing agencies and achieving cost-effective construction. We will be pleased to provide an estimate for these additional services once final plans and schedules are available. 8.0 LIMITATIONS AND UNIFORMITY OF CONDITIONS This report presents geotechnical recommendations for design of the improvements discussed in Section 1.3 for the development project. If changes occur in the nature or design of the project, we should be allowed to review this report and provide additional recommendations, if any. It is the responsibility of the owner to transmit the information and recommendations of this report to the appropriate organizations or people involved in design of the project, including but not limited to developers, owners, buyers, architects, engineers, and designers. The conclusions and recommendations contained in this report are solely professional opinions and are valid for a period of no more than 2 years from the date of report issuance. We strived to perform our professional services in accordance with generally accepted geotechnical engineering principles and practices currently employed in the area; no warranty is expressed or implied. There are risks of earth movement and property damages inherent in building on or with earth materials. We are unable to eliminate all risks or provide insurance; therefore, we are unable to guarantee or warrant the results of our services. This document must not be subject to unauthorized reuse that is, reusing without written authorization of ENGEO. Such authorization is essential because it requires ENGEO to evaluate the document’s applicability given new circumstances, not the least of which is passage of time.


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Actual field or other conditions will necessitate clarifications, adjustments, modifications or other changes to ENGEO’s documents. Therefore, ENGEO must be engaged to prepare the necessary clarifications, adjustments, modifications or other changes before construction activities commence or further activity proceeds. If ENGEO’s scope of services does not include onsite construction observation, or if other persons or entities are retained to provide such services, ENGEO cannot be held responsible for any or all claims arising from or resulting from the performance of such services by other persons or entities, and from any or all claims arising from or resulting from clarifications, adjustments, modifications, discrepancies or other changes necessary to reflect changed field or other conditions. We determined the lines designating the interface between layers on the exploration logs using visual observations. The transition between the materials may be abrupt or gradual. The exploration logs contain information concerning samples recovered, indications of the presence of various materials such as clay, sand, silt, rock, existing fill, etc., and observations of groundwater encountered. The field logs also contain our interpretation of the subsurface conditions between sample locations. Therefore, the logs contain both factual and interpretative information. Our recommendations are based on the contents of the final logs, which represent our interpretation of the field logs.

FIGURES

Figure 1 – Vicinity Map Figure 2 – Site Plan Figure 3 – Geologic Map Figure 4 – Geologic Map Figure 5 – Regional Faulting and Seismicity Map Figure 6 – Seismic Hazards Map Figure 7 – Historical Alignment of Strawberry Creek

FIGURES

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ORTIGALITA

GREENVILLE

SAN G

REG

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SAN ANDREAS

HAYWARD

POINT REYES

SAN ANDREAS

CONCO

RD

GR

EEN VALLEY

VAC

A

SAN JOAQUIN

ORTIGALITA

TOLAY

RODGERS CREEK

CO

RD

ELIA

MIDW

AY

SILVER CREEK

SAN JOSE

MONTE VISTA SHANNON

BERROCAL

ZAYANTE

VERGELES

SARGENT

DUNNIGAH HILLS

MAACAMA

CALAVERAS

CARNEGIE CORAL HOLLOW

WEST NAPA

BENNETT VALLEY

HU

NTIN

G C

REEK - BERRYESSA

ALEXANDER-REDWOOD HILL

GEYSER PEAK

COLLAYOMI

ANTIOCH

BEAR MO

UNTAINS

BEAR MOUNTAINS

MELONES

BEAR MOUNTAINS

TAHOE - SIERRA FRONTAL

G R

E A T V A L L E Y F A U L T

G R E A T V A L L E Y F A U L T

Santa Cruz Santa Clara

Merced

San MateoMariposa

Alameda

Stanislaus

Contra CostaSan Joaquin

MarinTuolumne

CalaverasSolano

AmadorSacramento

NapaSonoma Alpine

YoloEl Dorado

Lake

SanFrancisco

SAN ANDREAS

APPENDIX A

PSH Deaggregation

APPENDIX

A

0

10

20

30

40

50

Closest Distance, Rcd (km)0

10

20

30

40

50

Closest Distance, Rcd (km)

5.0

5.5

6.0

6.5

7.0

7.5

8.0

MAGNITUDE (Mw)

5.0

5.5

6.0

6.5

7.0

7.5

8.0

MAGNITUDE (Mw)

510

15

20

% C

ontr

ibutio

n to H

aza

rd

PSH Deaggregation on NEHRP D soilUnnamed 122.269o W, 37.869 N.Peak Horiz. Ground Accel.>=1.1671 gAnn. Exceedance Rate .404E-03. Mean Return Time 2475 yearsMean (R,M,ε0) 3.4 km, 6.79, 1.47Modal (R,M,ε0) = 2.6 km, 6.97, 1.32 (from peak R,M bin)Modal (R,M,ε*) = 2.6 km, 6.97, 1 to 2 sigma (from peak R,M,ε bin)Binning: DeltaR 10. km, deltaM=0.2, Deltaε=1.0

200910 UPDATE

ε0 < -2

-2 < ε0 < -1

-1 < ε0 <-0.5

-0.5 < ε0 < 0

0 < ε0 < 0.5

0.5 < ε0 < 1

1 < ε0 < 2

2 < ε0 < 3

Prob. SA, PGA

<median(R,M) >median

GMT 2012 Dec 8 00:54:44 Distance (R), magnitude (M), epsilon (E0,E) deaggregation for a site on soil with average vs= 300. m/s top 30 m. USGS CGHT PSHA2008 UPDATE Bins with lt 0.05% contrib. omitted

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GEOTECHNICAL EASIBILITY EPORT - Berkeley, California › uploadedFiles › Planning_and_Devel… · 2010 Crow Canyon Place, Suite 250 San Ramon, CA 94583 (925) 866-9000 Fax (888)