2200 Oxford Geotech Report Feb 05

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FUGRO WEST, INC. GEOTECHNICAL STUDY BROWER CENTER BERKELEY, CALIFORNIA Prepared for: OXFORD STREET DEVELOPMENT, LLC FEBRUARY 2005 Project No. 1683.001

Transcript of 2200 Oxford Geotech Report Feb 05

  • FUGRO WEST, INC.

    GEOTECHNICAL STUDY BROWER CENTER

    BERKELEY, CALIFORNIA

    Prepared for: OXFORD STREET DEVELOPMENT, LLC

    FEBRUARY 2005

    Project No. 1683.001

  • February 23, 2005 Project No. 1683.001

    Oxford Street Development, LLC P.O. Box 28585, (Building 38) San Francisco, California 94129

    Attention: Mr. John Clawson

    Subject: Geotechnical Study, Brower Center Berkeley, California

    Dear Mr. Clawson:

    Fugro West, Inc., is pleased to submit this geotechnical study report presenting the results of our field exploration and laboratory testing program for the Brower Center in Berkeley, California.

    We appreciate this opportunity to be of service to Oxford Street Development, LLC. Please contact Jon Hagen at (510) 267-4453 if you have any questions regarding the information presented in this report.

    Sincerely,

    FUGRO WEST, INC.

    Jon C. Hagen, P.E. Project Engineer

    Ronald L. Bajuniemi, P.E., G.E. Principal Consultant

    JCH/RLB:rp

    Copies Submitted: Mr. Ted Lieser (Equity Community Builders, LLC 2) Mr. Aaron Sage (City of Berkeley Planning and Development 1)

    1000 Broadway, Suite 200Oakland, California 94607

    Tel: (510) 268-0461Fax: (510) 268-0137

    FUGRO WEST, INC.

    A member of the Fugro group of companies with offices throughout the world.

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    CONTENTS

    Page

    1.0 INTRODUCTION.................................................................................................................. 1 1.1 Project Description ...................................................................................................... 1 1.2 Scope of Services ....................................................................................................... 1

    2.0 DATA REVIEW, EXPLORATION AND LABORATORY TESTING ...................................... 2 2.1 Review of Existing Data .............................................................................................. 2 2.2 Field Exploration.......................................................................................................... 2 2.3 Laboratory Testing ...................................................................................................... 2 2.4 Chemical testing.......................................................................................................... 3

    3.0 GEOLOGIC SETTING ......................................................................................................... 3 3.1 Regional Geology........................................................................................................ 3 3.2 Regional Seismicity ..................................................................................................... 4

    4.0 SITE CONDITIONS.............................................................................................................. 5 4.1 Surface Conditions ...................................................................................................... 5 4.2 Site Geology................................................................................................................ 5 4.3 Subsurface Conditions ................................................................................................ 5 4.4 Groundwater................................................................................................................ 6

    5.0 DISCUSSIONS AND CONCLUSIONS ................................................................................ 7 5.1 Seismicity and Geologic Hazards................................................................................ 7 5.2 Hydrostatic Forces ...................................................................................................... 8 5.3 Groundwater considerations ....................................................................................... 8 5.4 Foundation Support..................................................................................................... 9 5.5 Construction Considerations ....................................................................................... 9

    6.0 RECOMMENDATIONS...................................................................................................... 10 6.1 Seismic Design.......................................................................................................... 10 6.2 Site Preparation and Grading.................................................................................... 11

    6.2.1 Site Preparation............................................................................................. 11 6.2.2 Subgrade Preparation ................................................................................... 11 6.2.3 Engineered Fill Materials............................................................................... 11 6.2.4 Fill Placement and Compaction..................................................................... 12 6.2.5 Trench Backfill ............................................................................................... 12 6.2.6 Temporary Shoring and Construction Slope ................................................. 13 6.2.7 Dewatering .................................................................................................... 13 6.2.8 Surface Drainage .......................................................................................... 13 6.2.9 Guide Specifications...................................................................................... 13

    6.3 Foundations............................................................................................................... 13 6.3.1 Mat Foundation ............................................................................................. 13

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    CONTENTS - CONTINUED

    Page

    6.3.2 Spread Footings and Slabs-on-Grade........................................................... 14 6.3.2.1 Spread Footings ....................................................................... 14 6.3.2.2 Slabs-on Grade......................................................................... 14

    6.4 Below-Grade Walls.................................................................................................... 16 6.5 Lateral and Uplift Load Resistance ........................................................................... 17 6.6 Additional Geotechnical Services.............................................................................. 17

    7.0 LIMITATIONS..................................................................................................................... 18

    PLATES

    Plate

    Vicinity Map................................................................................................................................... 1 Site Plan........................................................................................................................................ 2 At-Rest Lateral Pressure............................................................................................................... 3 Active Lateral Pressure................................................................................................................. 4 Subdrain for Below-Grade Garage Floor ...................................................................................... 5

    APPENDICES

    APPENDIX A FIELD EXPLORATIONS Key to Soil Classification and Test Data........................................................................ Plate A-1 Exploratory Boring Logs .....................................................................................B-1 through B-4 Summary of Previous Boring Logs by Others

    APPENDIX B LABORATORY TESTING PROGRAM Plasticity Chart and Data ............................................................................................... Plate B-1 Gradation Test Data ...................................................................................................... Plate B-2 Unconfined Compression Test Data.............................................................................. Plate B-3

    APPENDIX C CHEMICAL LABORATORY DATA

    APPENDIX D GUIDE SPECIFICATIONS SITE EARTHWORK

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    1.0 INTRODUCTION

    This report presents the results of the geotechnical study conducted by Fugro West, Inc., (Fugro) for the Brower Center. The project site is situated on the west side of Oxford Street between Allston Way and Kittredge Street, as shown on the Vicinity Map, Plate 1 in Berkeley, California.

    1.1 PROJECT DESCRIPTION

    Based on the information indicated on the Site Plan, Plate 2, as well as on our conversations with Equity Community Builders, LLC, it is our understanding that the development will consist of a new mixed commercial and residential building with associated improvements. The building will have five to six stories above grade. One to two levels of underground parking will be constructed. If two levels of below-grade parking are built, excavations could extend to 22 to 28 feet below grade. If one level is chosen, this level would be lowered approximately 3 to 4 feet to accommodate parking lifts. The building footprint will occupy the entire site. Building loads are anticipated to be typical for the proposed type of construction. Moderate grading will be required to develop the site for the subject project.

    1.2 SCOPE OF SERVICES

    The purpose of our geotechnical and field exploration and laboratory-testing program was to obtain information on subsurface conditions in order to evaluate the geotechnical aspects of the project. The evaluation of groundwater quality was also investigated to develop recommendations for disposal during construction dewatering. The scope of our services performed included:

    Compiling and reviewing available geotechnical and geologic data that is contained in our files and is pertinent to the project vicinity;

    Conducting a field exploration and laboratory-testing program to supplement the available information on subsurface conditions;

    Evaluating if construction dewatering is suitable for direct discharge to the storm drain of if treatment of the water is required prior to discharge; and

    Preparing this geotechnical report presenting the results of our geotechnical field exploration, laboratory testing program, discussion of groundwater quality issues and recommendations for disposal, discussion of geotechnical issues, and geotechnical recommendations.

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    2.0 DATA REVIEW, EXPLORATION AND LABORATORY TESTING

    The exploration and laboratory-testing program described herein was developed to provide general characterization of the subsurface materials.

    2.1 REVIEW OF EXISTING DATA

    Prior to conducting our field exploration and laboratory testing, Fugro reviewed relevant information relating to geotechnical, geologic, and seismic information, as well as results of previous explorations performed within the vicinity of the site including a report by Harza Engineering Company (now part of Fugro) titled, Geotechnical Investigation, GAIA Building, Berkeley, California, dated November 25, 1998. Three borings, PB-1, PB-2, and PB-3, from this report were in the immediate vicinity of the project site and their locations are presented in the Site Plan, Plate2. A summary of Previous Borings PB-1, PB-2, and PB-3 is included in Appendix A.

    2.2 FIELD EXPLORATION

    We conducted a total of four exploratory borings as a part of the geotechnical study for the Brower Center project. The exploration was conducted between December 29 and 30, 2004. The exploratory borings, designated B-1 through B-4, were drilled with a truck-mounted drill rig using hollow stem augers. The borings extended to depths of 45 to 50 feet. It is noted that Boring B-4 was moved east of its original position due to the presence of an obstruction at a depth of approximately 3 feet at its original location. The original location was near the southwest corner of the parking lot, adjacent to the existing structure at 2119 Kittredge Street. The approximate locations of the exploratory borings are shown on the Site Plan, Plate 2.

    Boring B-1 was converted to a piezometer by installing two-inch PVC casing with a screen section between 25 and 35 feet. The perforations of the screen were 0.02 inches. The solid casing extended from the ground surface to 25 feet and from 35 to 45 feet. We backfilled the annulus of the casing below 25 feet with a medium grained sand. We placed about one foot of bentonite pellets over the sand and the upper portion of the boring was backfilled with neat cement grout. On December 30, 2004, a Fugro representative purged the piezometer of about 25 gallons of water and stored the water in a metal drum. We observed that clear water had flowed into the piezometer before we performed the sampling. We then collected samples of the water from the piezometer and stored the samples in a cooled ice chest until delivery to a state-certified laboratory for chemical analyses.

    Logs of the exploratory borings and details regarding the field explorations are included in Appendix A. The subsurface conditions encountered in the exploratory borings are summarized in Section 4.0.

    2.3 LABORATORY TESTING

    Geotechnical laboratory testing was conducted on the soil samples collected from the borings at Fugros soil mechanics laboratory in Oakland, California. The geotechnical

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    laboratory test program included: classification tests (gradation, fines content, Atterberg limits, water content, unit weight) and strength tests (unconfined compression tests). The results of the laboratory tests are presented on boring logs (Appendix A) at the appropriate sample depths, and in Appendix B, Laboratory Test Results.

    2.4 CHEMICAL TESTING

    Fugro conducted the following chemical tests on the groundwater sample from the piezometer at B-1:

    1. Volatile organic compounds (VOCs) for EPA Test Method 8260B with oxygenates and Ethylene Dibromide;

    2. Total Petroleum Hydrocarbons (TPH) for EPA Test Method 8015 as gasoline, diesel, and motor oil with silica gel cleanup;

    3. Semi-volatile organic compounds (SVOCs) for EPA Test Method 8270; and

    4. Inorganic constituents including: mercury, cadmium, silver, antimony, beryllium, total chromium, copper, lead, nickel, selenium, thallium, zinc, arsenic, and cyanide by the appropriate EPA Test Methods.

    The laboratory data is presented in Appendix C, Chemical Laboratory Data.

    3.0 GEOLOGIC SETTING

    3.1 REGIONAL GEOLOGY

    The site is located in the Coast Ranges geomorphic province, which is characterized by northwest-southeast trending valleys and ridges. These are controlled by folds and faults that resulted from the collision of the Pacific and North American plates and subsequent strike-slip faulting along the San Andreas fault zone. Bedrock underlying the region is primarily of the Franciscan Complex, which is characterized by a diverse assemblage of sandstone, shale, chert, greenstone, and melange.

    Geologic formations in the San Francisco Bay Region range in age from Jurassic to Recent Holocene. The Franciscan Complex is the oldest, and underlies younger surficial deposits throughout the San Francisco Bay Region. The Franciscan Complex consists mainly of marine-deposited sedimentary and volcanic rocks in close association with bodies of serpentine. Following deposition, the Franciscan rocks were regionally uplifted and, in the process, extensively faulted and folded.

    The Bay Area also experienced uplift and faulting in several episodes during late Tertiary time (about 25 to 2 million years ago). This produced a series of northwest-trending valleys and mountain ranges, including the Berkeley Hills, the San Francisco Peninsula, and the intervening San Francisco Bay. Uplifted areas were eroded and as a result, Pleistocene and recent marine sediments were deposited in the San Francisco Bay, and stream and marshland sediments were deposited in low-lying areas adjacent to the Bay.

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    3.2 REGIONAL SEISMICITY

    The project site is located in the San Francisco Bay Area, which is considered one of the most seismically active regions in the United States. Significant earthquakes have occurred in the San Francisco Bay Area and are believed to be associated with crustal movements along a system of sub-parallel fault zones that generally trend in a northwesterly direction.

    In 2003, the Working Group 2002 on California Earthquake Probabilities (WG2002), in conjunction with the United States Geological Survey (USGS), published an updated report evaluating the probabilities of significant earthquakes occurring in the Bay Area over the next three decades. WG2002 finds that there is a 62 percent probability that at least one magnitude 6.7 or greater earthquake will occur in the San Francisco Bay region from 2003 to 2032. This probability is an aggregate value that considers seven principal Bay Area fault systems and unknown faults (background values). The San Francisco Bay region continues to be seismically active. The principal active faults in the Bay Area include the San Andreas, Hayward, Calaveras, and the San Gregorio faults. Earthquakes occurring along these faults are capable of generating strong ground shaking at the project site.

    The approximate distance of the site from the 5 closest known mapped faults1 is summarized in Table 1. According to the State of California Special Studies Zones map (1982), the project site is not located within an Alquist-Priolo Earthquake Fault Zone.

    Regional Faults and Seismicity2

    Fault Approximate Distance from Site Direction from Site

    Maximum Moment Magnitude

    Fault Type

    Hayward 0.8 miles (1.3 km) Northeast 7.1 A

    Calaveras (north) 12.7 miles (20.4 km) East 6.8 B

    Concord Green Valley 14.5 miles (23.4 km) Northeast 6.9 B

    Rodgers Creek 15.5 miles (25.0 km) North 7.0 A

    San Andreas (1906) 17.6 miles (28.3 km) Southwest 7.9 A

    Earthquakes on these or other smaller, more distant, or unmapped faults could cause strong ground shaking at the site. Earthquake intensities vary throughout the Bay Area depending upon the magnitude of the earthquake, the distance of the site from the causative fault, the type of materials underlying the site, and other factors.

    1 According to the Maps of Known Active Fault Near-Source Zones in California and Adjacent Portions of Nevada,

    prepared by California Department of Conservation, Division of Mines and Geology (1998). 2 Maximum Moment Magnitude and Fault Type are based on 1997 UBC designations.

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    4.0 SITE CONDITIONS

    4.1 SURFACE CONDITIONS

    As shown on the Site Plan, Plate 2, the site is trapezoidal in shape, slopes slightly to the west and southwest and has maximum plan dimensions of approximately 195 by 270 feet. The maximum elevation difference across the site is approximately 7 feet between the northeast corner and southwest corner. The site is bound by Oxford Street on the east, Allston Way on the north, Kittredge Street on the south and private businesses on the west. At the time of our field exploration, the site was an asphalt parking lot. Vegetation consisted of medium to large trees in planter areas within the parking lot and on the sidewalks along the surrounding streets. Medium-sized shrubs bordered the parking lot on the north and south sides.

    4.2 SITE GEOLOGY

    According to Radbruch (1957)3, the area of the project site is mapped as Quaternary alluvial fan deposits of the Temescal Formation (Qtc). The alluvium consists of interfingering lenses of clayey gravel, sandy silty clay, and sand-clay-silt mixtures.

    4.3 SUBSURFACE CONDITIONS

    The surface soils encountered in our borings consisted of very stiff to hard sandy clay that extended to depths of 7 to 17 feet. These clayey soils have a low plasticity and a low expansion potential. The clay layer was thicker in the north and northwest portions of the site. No sandy clay was encountered in Boring B-4 near the southwest corner of the site. Below these soils, and from the surface in Boring B-4, we encountered dense to very dense sandy gravel and gravelly sand, which extended to depths of 21 to 28 feet. Very stiff to hard silty to sandy clay was encountered below the sand layer to depths of 37 feet 46 feet. Medium dense to very dense clayey sand and sand with gravel and stiff clay was encountered from depths of 37 feet to the maximum depth explored of 50 feet. Detailed descriptions of the soils encountered in each of the exploratory borings are presented on the boring logs in Appendix A.

    Based on Previous Borings PB-1 through PB-3, the subsurface conditions immediately to the west of the site consisted of dense to very dense clayey sands and gravels interlayered with stiff to hard clays extending depths of 26 to 30 feet. Stiff to hard clay was encountered below 26 to 30 feet to the maximum depth explored of about 71 feet.

    The attached boring logs and related information depict location specific subsurface conditions, encountered during our field investigation. The approximate locations of the borings were determined by taping and should be considered accurate only to the degree implied by the method used. The passage of time could result in changes in the subsurface conditions due to environmental changes.

    3 Radbruch, Dorothy H., Areal and Engineering Geology of the Oakland West Quadrangle, California, USGS, Miscellaneous

    Geologic Investigations, Map I-239, 1957.

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    4.4 GROUNDWATER

    Free groundwater was observed in Borings B-1, B-2, B-3, and B-4 at depths of approximately 18 to 23 feet at the time of drilling. All borings were backfilled immediately after drilling. With exception of Boring B-1, the borings were backfilled with a neat cement grout in accordance with the City of Berkeley requirements. We note that the borings may not have been left open for a sufficient period of time to establish equilibrium ground water conditions. In addition, fluctuations in the ground water level could occur due to changes in seasons, variations in rainfall, and other factors. Boring B-1 was backfilled with an open standpipe piezometer. The water level as measured on January 5, 2005, at a depth of 16.1 feet (Elevation 173.9 feet). For design purposes, a groundwater depth of 14 feet should be used. This corresponds to an Elevation of +176 feet. If excavations are deepened to below Elevation +176 feet, then Oxford Street Development, LLC will have to plan to extract and discharge the groundwater.

    Groundwater was encountered in Previous Borings PB-1, PB-2, and PB-3, located immediately to the west of the site, at depths of 20, 14, and 14 feet, respectively, during drilling. These borings were backfilled immediately upon completion of the borings.

    The laboratory reports for the groundwater contamination analyses are presented in Appendix C. The results indicate that no TPH gasoline, TPH diesel, TPH motor oil, Ethylene Dibromide, and no SVOCs were present in the sample from B-1. The groundwater sample contained 1.5 micrograms per liter (ug/l) of chloroform. Chloroform is a volatile organic compound (VOC) that is commonly used in laboratories during their analyses. Chloroform is also present in drinking water supplies. Discharge limits of 5.0 ug/l for VOCs are usually applicable for dewatering projects. Therefore, the presence of chloroform at a concentration of 1.5 ug/l is not an indication of contamination that requires abatement.

    Summary of Analytical Results Groundwater Analyte B-1

    VOCs ND*

    TPH as diesel and motor oil ND

    TPH gasoline ND

    SVOCs ND

    *1.5 ug/l of chloroform was detected

    We analyzed the groundwater sample for the CAM 17 metals, and the laboratory detected Chromium, Copper, Lead, Selenium, Thallium and Zinc. The results of the metals analyses are compared against the trigger concentrations that, if exceeded, require additional sampling, chemical testing, and evaluation to determine if treatment is required. The Trigger Concentrations are listed in Order No. R2-2004-0055, NPDES No. CAG912003 as General Discharge Requirements for discharge or reuse of extracted or treated groundwater resulting from the cleanup of groundwater polluted by VOCs.

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    Summary of Metals Results at B-1 - Groundwater

    Analyte B-1 Concentration Trigger Concentration

    Metals

    Antinomy

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    produce strong groundshaking at the site. For this reason, the structures should be designed to resist lateral and uplift forces generated by earthquake shaking, in accordance with local design practice.

    Settlement can occur as a result of seismic groundshaking due to liquefaction or densification of the subsurface soils. In both liquefaction and densification, groundshaking causes predominantly granular soils to become more compact, therefore occupying less volume and resulting in settlement. Soils most susceptible to liquefaction and densification are loose, clean, poorly graded, fine-grained sands. Liquefaction can occur where soils are saturated (submerged), and is accompanied by a temporary loss of strength (i.e., the soil liquefies). Densification can occur where the soils are unsaturated.

    According to the California Geologic Survey (2003)4, the site is located just outside a liquefaction hazard area. The former alignment of Strawberry Creek is located directly west of the site and is designated as an area of liquefaction hazard. According to the Association of Bay Area Governments (ABAG) liquefaction susceptibility maps found at http://gis.abag.ca.gov/website/liq/viewer.htm the entire project site is in an area considered to have a low potential for liquefaction. The soils encountered during our exploration consist predominantly of dense to very dense sands and gravels and very stiff to hard clays and have sufficient density or cohesion to not be prone to liquefaction.

    Other geologic hazards such as slope instability, lurching, or fault rupture are considered to be unlikely at this site due to the relatively flat terrain and the distance from a known active fault.

    5.2 HYDROSTATIC FORCES

    The possible presence of shallow groundwater will cause hydrostatic forces to act on the structure, unless the below-grade parking structure is permanently drained or a one-level below-grade parking structure that is founded above the groundwater level is constructed. Based on our piezometer readings, we recommend that a groundwater depth of 14 feet (Elevation +176 feet) be used for design. It is our understanding that if the 2-level below-grade parking structure is constructed, it will extend to about 8 to 9 feet below the recommended design groundwater level. Therefore, unless the 2-level below-grade structure is drained, the structure must be designed to resist the hydrostatic pressure including uplift. Recommendations for resisting uplift forces on the proposed structure are provided in Section 6.6, Lateral and Vertical Load Resistance.

    5.3 GROUNDWATER CONSIDERATIONS

    If the onsite excavation exceeds 14 feet, the Oxford Street Development, LLC can consider dewatering the excavation and discharging the water to the storm drain or the sanitary sewer. The chemical test results indicate that no significant concentrations of contaminants are

    4 Seismic Hazard Zone Report for the Oakland West 7.5-Minute Quadrangle, Alameda County, California, California Geologic

    Survey, 2003.

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    present in the groundwater from Boring B-1. Discharging the groundwater from the site to the to the sanitary sewer will require the approval of the City of Berkeley and the East Bay Municipal Utility District (EBMUD) because the water would flow through the sanitary sewer lines of the City of Berkeley and to the EBMUC waste water treatment plant. Discharge to the storm drain under the City of Berkeleys permit will require approval of the Regional Water Quality Control Board (RWQCB) and the City of Berkeley because the water would flow through the storm drains and discharge to Strawberry Creek and/or other creeks in Berkeley. For construction dewatering considerations, Fugro believe that discharges to the storm drain will be less costly and easier to gain approval than a discharge permit to the sanitary sewer.

    On the basis of the chemical data from the Piezometer B-1, Fugro believes that the contractor will be able to gain authorization from the Regional Water Quality Control Board (RWQCB) and the City of Berkeley to discharge the groundwater to the storm drain. To meet the requirements of the RWQCB, the Oxford Street Development, LLC will be required to file a Notice of Intent and to develop a Storm Water Pollution Prevention Plan (SWPPP). For a temporary dewatering permit, Fugro believe that the Oxford Street Development, LLC will be able to meet their discharge requirements by removing the total suspended solids (TSS) in the effluent to below 30 milligrams per liter (mg/l) using tanks. Fugro believes that the sediment removal to a TSS of 30 mg/l will also reduce the metals concentrations to concentrations below discharge limits. Monthly monitoring of the discharge flows will probably be needed to document the discharges from the site.

    Long-term discharges from the Site will probably have to meet more restrictive discharge limits. These more restrictive discharge limitations would be established through a formal permit with the RWQCB.

    5.4 FOUNDATION SUPPORT

    Based on the results of our exploration, we judge that if the proposed structure contains two levels of below-grade parking, it can be supported on a mat foundation system bearing on either competent native soil or engineered fill. Alternatively, if the below-grade structure is drained, the structure can be supported on either spread footings or a mat foundation. If the structure will contain only one level of below-grade parking above the design groundwater elevation, it can be supported on either spread footings or a mat foundation. The long-term total and differential static settlement of mat and/or spread footing foundations constructed as recommended in this report should be considered in the design of the foundations. The geotechnical recommendations presented in Section 6.0 of this report include details judged to be appropriate for the soils present at the project site.

    5.5 CONSTRUCTION CONSIDERATIONS

    Excavation for construction of the one- to two-level below-grade garage will need to be performed immediately adjacent to existing buildings, sidewalks, and pavements. On the basis of this layout, it appears that shoring and/or temporary slopes will be required during excavation, construction of the basement level, and backfilling to protect these adjacent elements. The design and maintenance of all necessary shoring and temporary excavation slopes is the

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    responsibility of the Contractor. Excavations will be required to construct spread footings, mats, below ground parking, and to install utilities. All excavations that will be deeper than 5 feet and will be entered by workers should be shored or sloped for safety in accordance with Occupational Safety and Health Administration (OSHA) standards.

    If excavation extends below an imaginary plane projecting downward at 1.5:1 (horizontal to vertical) from existing foundations, the existing foundations should either be underpinned or shoring should be designed to keep construction settlement of the foundations within acceptable limits. As with the shoring, the design and installation of all necessary underpinning would be the responsibility of the Contractor.

    Groundwater was measured in our piezometer at a depth of about 16 feet and is considered to be 14 feet for design. If the lowest level extends below a depth of 14 feet, dewatering by the Contractor will be required to control groundwater during construction.

    The Contractor should thoroughly document the condition of nearby buildings, streets, and utilities by video or other means prior to the commencement of site excavation. The Contractor should also perform regular surveys during excavation and construction to monitor and document any observed settlement of nearby streets and structures.

    6.0 RECOMMENDATIONS

    6.1 SEISMIC DESIGN

    The structures should be designed to resist the lateral forces generated by earthquake shaking in accordance with local design practice. This section presents seismic design criteria for use with the 1997 UBC.

    As defined in the 1997 UBC, we judge the following criteria to be appropriate for the site:

    Seismic Zone Factor Z= 0.4 Soil Profile Type SD Near Source Factor Na= 1.5 Seismic Coefficient Ca = 0.44Na = 0.66 Near Source Factor Nv= 2.0 Seismic Coefficient Cv= 0.64Nv = 1.28

    The near source factors Na and Nv are greater than unity as a result of the sites proximity to a Type A fault (the Hayward Fault). The near source factors Na and Nv are equal to unity at distances greater than or equal to 10 kilometers and 15 kilometers, respectively, from a Type A fault.

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    6.2 SITE PREPARATION AND GRADING

    6.2.1 Site Preparation

    The site should be cleared of all obstructions, including concrete, asphalt pavement, buried foundations, slabs, utility lines, trees and associated root systems, and debris. Removed concrete, asphalt concrete, and baserock may be reused as fill, provided it is broken up to meet the requirements in Section 6.2.3, Engineered Fill Materials. It should be anticipated that holes resulting from the removal of root systems of larger trees could extend to depths of 3 feet, and laterally to the drip line of each tree. Holes resulting from the removal of underground obstructions extending below the proposed finish grade and outside of the parking garage excavation should be cleared and backfilled with suitable material compacted to the requirements in Section 6.2.4, Fill Placement and Compaction. We recommend backfilling operations for any excavations to remove deleterious material be carried out under the observation of the Geotechnical Engineer.

    After clearing, the portions of the site containing surface vegetation or organic laden topsoil (i.e., planter areas) and are not located in the footprint of the below-grade parking structure, should be stripped to an appropriate depth to remove these materials. At the time of our field investigation, we estimated that a stripping depth of approximately 3 inches would be required. The amount of actual stripping should be determined in the field by the Geotechnical Engineer at the time of construction. Stripped materials should be removed from the site, or stockpiled for later use in landscaping, if approved by the owner.

    6.2.2 Subgrade Preparation

    Following excavation to the required grades, soil subgrades in areas to receive below-grade slabs, slabs-on-grade or pavements should be scarified to a depth of at least 6 inches, moisture conditioned to slightly above optimum moisture content, and compacted to minimum 90 percent relative compaction. The top 6 inches of subgrade in areas to receive pavements should be moisture conditioned and compacted to at least 95 percent relative compaction. The compacted surface should be firm and unyielding and should be protected from damage caused by traffic or weather. Soil subgrades should be kept moist during construction. If the subgrade is allowed to become dry, it should be moisture conditioned to eliminate shrinkage cracks.

    In order to achieve satisfactory compaction of the subgrade and fill materials, it may be necessary to adjust the water content at the time of construction. This may require that water be added to soils that are too dry, or that scarification and aeration be performed in any soils that are too wet.

    6.2.3 Engineered Fill Materials

    All fill placed at the site should consist of engineered fill meeting the requirements presented in this report, except for landscaping materials which are placed on level ground. Onsite soil below the stripped layer and having an organic content of less than 3 percent by volume can be used as fill. All engineered fill placed at the site, including onsite soils, should

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    not contain rocks or lumps larger than 4 inches in greatest dimension and contain no more than 15 percent larger than 2.5 inches. Imported fill should be predominantly granular have an organic content of less than 3 percent by volume, should have a liquid limit less than 40 percent, have a plasticity index not exceeding 15, and should contain no environmental contaminants or debris.

    6.2.4 Fill Placement and Compaction

    Engineered fill less than 5 feet thick should be compacted to at least 90 percent relative compaction as determined by ASTM Designation D1557-91. The upper 6 inches of subgrade soils beneath pavements should be compacted to at least 95 percent relative compaction. Engineered fill or wall backfill greater than 5 feet deep should be entirely compacted to at least 95 percent relative compaction. Fill material should be spread and compacted in lifts not exceeding 8 inches in uncompacted thickness. In order to achieve satisfactory compaction of the subgrade and fill materials, it may be necessary to adjust the water content at the time of construction. This may require that water be added to soils that are too dry, or that aeration be performed in any soils that are too wet.

    6.2.5 Trench Backfill

    Pipeline trenches should be backfilled with materials satisfying the criteria described above for fill, placed in lifts of approximately 8 inches in uncompacted thickness. However, thicker lifts may be used provided the method of compaction is approved by the project geotechnical engineer and the required minimum degree of compaction is achieved. Onsite soil used for trench backfill should be compacted to at least 90 percent relative compaction by mechanical means only (jetting should not be permitted). Sand can be used for trench backfill if it is compacted to at least 95 percent relative compaction and sufficient water is added during backfilling operations to prevent the soil from bulking during compaction. The upper 3 feet of trench backfill below slab and pavements should be compacted to at least 95 percent relative compaction.

    All utility trenches that extend below curbs and gutters adjacent to landscaped areas should be backfilled by an impermeable plug. The plugs can be composed of compacted clayey soil, compacted bentonite, or a bentonite-cement or sand-cement slurry mixture. The plugs should be at least 2 feet thick and should extend at least 2 feet beyond the edges and bottom of the trench to key in the plug. The plug should also extend to within 1 foot of the lowest adjacent grade. The plug should be located below the curb and gutter.

    Pipeline trenches should be backfilled with fill placed in lifts of approximately 8 inches in uncompacted thickness. However, thicker lifts can be used, provided the method of compaction is approved by the Geotechnical Engineer, and the required minimum degree of compaction is achieved.

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    6.2.6 Temporary Shoring and Construction Slope

    Temporary shoring or construction slopes may be necessary for construction of the below-grade parking structure. The owner and the Contractor should be familiar with applicable local, state, and federal regulations for both temporary construction slopes, and shoring, including the current OSHA Excavation and Trench Safety Standards. The Contractor should be solely responsible for the design, construction, and performance of temporary shoring. Temporary slopes should be designed assuming that granular Type C soils will be exposed in the excavation slopes.

    6.2.7 Dewatering

    The presence of groundwater will necessitate dewatering to control the groundwater during the excavation for construction of the below-grade parking structure if the structure extends below a depth of 14 feet. We recommend that water be drawn down at least 2 feet below the deepest part of the excavations to provide dry working conditions and to help minimize instability of the excavation bottoms. The Contractor should be solely responsible for the design, construction, and the performance of dewatering system.

    6.2.8 Surface Drainage

    Positive surface gradients of at least 2 percent should be provided adjacent to the building to direct surface water away from foundations and slabs toward suitable discharge facilities. Ponding of surface water should not be allowed adjacent to the structure or on pavements.

    6.2.9 Guide Specifications

    All earthwork operations should be performed in accordance with the Guide Specifications - Site Earthwork presented in Appendix D. These specifications are general in nature, and the final specifications should incorporate all recommendations presented in this report.

    6.3 FOUNDATIONS

    6.3.1 Mat Foundation

    Fugro recommends that the building be supported on a mat foundation system bearing on either undisturbed native, or engineered fills, using the maximum allowable bearing pressures presented below for one- and two-level below grade parking:

    Load Condition Allowable Bearing Pressure(psf) for One Level of Below-

    Grade Parking

    Allowable Bearing Pressure(psf) for Two Levels of Below-Grade Parking

    Dead Load 2,000 3,000 Dead plus Live Loads 3,000 4,500 Total Loads (including wind or seismic) 4,000 6,000

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    We recommend that a modulus of subgrade of 150 kips per cubic foot (kcf) be used for the design of the mat foundation. This value is based on a 1-foot-square bearing area and needs to be scaled to account for mat foundation size effects. To obtain the modulus of subgrade reaction for a given mat foundation, the value of 150 kcf should be divided by the width of the effective loaded area, in feet. Unless drainage is provided to lower the groundwater level to below the mat foundation, the mat foundation should be designed to resist hydrostatic uplift as discussed in Section 6.5, Lateral and Vertical Load Resistance. We estimate that the long-term total and differential settlement of new mat foundations constructed as recommended in this report should be on the order of -inch.

    Resistance to lateral loads can be developed in accordance with the recommendations presented in Section 6.5, Lateral and Vertical Load Resistance.

    6.3.2 Spread Footings and Slabs-on-Grade

    6.3.2.1 Spread Footings

    As an alternative, if the parking structure contains two levels and drainage is provided to lower the groundwater below the foundation level or if one level of below-grade parking above the groundwater table is constructed, the structure may be supported on conventional continuous and isolated spread footings bearing on undisturbed native soils. Footings should be at least 12 inches wide and should be founded at least 18 inches below lowest adjacent finished grade. Footings located adjacent to other footings or utility trenches should bear below an imaginary 1.5:1 (horizontal to vertical) plane projected upward from the bottom edge of the adjacent footings or utility trench. Footings should be designed to resist the lateral loads described in Section 6.5, Lateral and Vertical Load Resistance.

    Load Condition Allowable Bearing Pressure(psf) for One Level of Below-

    Grade Parking

    Allowable Bearing Pressure(psf) for Two Levels of Below-Grade Parking

    Dead Load 2,500 3,800 Dead plus Live Loads 3,750 5,700 Total Loads (including wind or seismic) 5,000 7,600

    Based on these loads we estimate that settlements of the structure will be on the order of inch.

    Any visible cracks in the bottoms of the footing excavations should be closed by wetting prior to construction of the foundations. We recommend that we observe the footing excavations prior to placing reinforcing steel or concrete, to check that footings are founded on appropriate material. All foundation excavations should be cleaned of loose material and should be free of water. The footings should be kept moist prior to concrete placement.

    6.3.2.2 Slabs-on Grade

    We recommend that interior slabs-on-grade should be supported on properly prepared subgrade or engineered fill as described previously under Section 6.2.2, Subgrade Preparation.

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    Slab-on-grade subgrade surfaces should be proof-rolled to provide a smooth, unyielding surface for slab support.

    We recommend that the below-grade slabs be designed either 1) to resist hydrostatic uplift pressures and appropriately waterproofed, or 2) with a subdrain system to relieve hydrostatic uplift pressures and appropriately moisture proofed. For a one-level below grade parking garage constructed above the groundwater level, waterproofing is not required, but a subdrain system and moisture proofing as described for the second option below, should be used. Recommendations for these two approaches are presented below.

    Waterproofing and Designing for Hydrostatic Pressures

    The lowest level floor may be waterproofed and designed to resist the hydrostatic uplift pressures. The waterproofing layer may consist of one of the following.

    Prefabricated panels of a bentonite clay based product installed directly onto the exposed soil subgrade or on a mud slab poured onto the soil subgrade. To provide for additional waterproofing layer, we recommend that this prefabricated panel consists of the two-layer type which has an additional layer, such as an impermeable membrane affixed onto the bentonite layer. We recommend that these panels may consist of Paraseal by Pramount Technical Products, Inc. or Volltex by Cetco, a division of American Colloid, or equivalent. We do not recommend that panel with only the bentonite layer, such as Volclay by Cetco, be used.

    Sprayed-on bentonite, applied directly onto the exposed soil subgrade or on a mud slab poured onto the soil subgrade. With this system, bentonite granules are mixed with a resin and sprayed onto the exposed soil subgrade or mud slab.

    Hot mopped layer, applied to a mud slab poured onto the soil subgrade. Hydrostatic uplift pressure can be resisted by the dead load of the structure.

    Subdrain System and Moisture Proofing

    The lowest level floor may be designed with a subdrain system and moisture proofed. The subdrain system would intercept the ground water before it encounters the floor, and thus, the floor need not to be designed to resist hydrostatic pressures. Floor subdrains need to be provided beneath the entire building area. The floor subdrain system may consist of perforated pipes spaced approximately 30 feet on-center, imbedded in permeable material, as shown on Plate 5. Collector pipes should drain the collected water to a minimum of two sumps from which the water would need to be pumped to a suitable discharge facility. The sumps should be located at opposite ends of the garage.

    To provide for moisture proofing of the slab, a layer similar to what was recommended above for waterproofing should be provided. Thus, prefabricated bentonite panels or sprayed-on bentonite or hot mopping should be provided. Prefabricated bentonite panels or sprayed-on bentonite may be placed directly on the drainage layer. Hot mopping should be performed on a

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    mud slab poured on the drainage layer. The floor slab may be constructed directly on the moisture-proofing layer.

    In addition to the above recommendations for waterproofing and moisture proofing, appropriate slab reinforcement should be provided in accordance with the anticipated loading of the slab including, if appropriate, hydrostatic uplift pressures.

    6.4 BELOW-GRADE WALLS

    Below-grade walls must be designed to resist both lateral earth pressures and any additional lateral loads caused by surcharging.

    We recommend that below-grade walls be designed as restrained walls. Above the design groundwater level (Elevation +176 feet), undrained, restrained walls should be designed to resist lateral earth pressures corresponding to an equivalent fluid weight of 35 pounds per cubic foot (pcf) plus an additional uniform lateral pressure of 8H pounds per square foot (psf), where H is the height of backfill above the top of the wall footing, in feet. Below the design groundwater level, the equivalent fluid weight should be increased to 85 pcf plus an additional uniform lateral pressure of 8H pounds per square foot (psf) to account for hydrostatic pressures. The above lateral pressures assume a level backfill. In addition, walls with inclined backfill should be designed for an additional equivalent fluid pressure of 1 pcf for every 2 degrees of slope inclination. Walls subject to surcharging should also be designed for an additional uniform lateral pressure equal to one-half the anticipated surcharge load for the restrained walls.

    During seismic loading, walls should be designed to resist the loads as shown in Plate 4. Recommended design lateral pressures for at-rest and active lateral earth pressures are presented on Plates 3 and 4.

    The above recommendations assume that the walls will be undrained. Should the walls be fully backdrained or if the below-grade parking structure does not extend below the design groundwater level (14 feet), the equivalent fluid weight may be assumed to be 35 pcf plus an additional uniform lateral pressure of 8H pounds per square foot (psf) for the entire wall height. Adequate drainage could be provided by a system of subdrains.

    For the subdrain system, the top of the perforated pipe should be below the bottom of the adjacent slab or grade. Drains should consist of a drain rock layer at least 12 inches thick that extends to within 2 feet of the ground surface. Four-inch diameter perforated plastic pipe should be installed (with perforations down) along the base of the walls on a two-inch-thick bed of drain rock. The pipe should be sloped to drain by gravity to a suitable drainage facility. Drain rock should conform to Caltrans specifications for Class 2 permeable material. A more open-graded material, such as -inch crushed rock, could be used provided the rock is surrounded by a geotextile filter fabric (Mirafi 140 N or equivalent) to reduce the migration of fine-grained soils into the drain rock. Paving or a two-foot-thick cap of clayey soil should be placed over the drain rock to inhibit surface water infiltration. Alternatively, wall back-drainage can be provided by prefabricated drainage material (such as Miradrain 6000 or an approved alternative). The drainage material can be installed on the back (soil) face of the basement wall and should

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    terminate at a 4-inch-diameter perforated plastic pipe surrounded by at least 6 inches of drain rock as defined above. Drain pipes should outlet to an appropriate drainage facility.

    Surcharge loads from adjacent structures need to be considered if the proposed below-grade walls extend below the zone of influence of adjacent foundations. The zone of influence of adjacent foundations can be defined as the area below an imaginary 1.5:1 (horizontal to vertical) line extending downwards from the bottom of the footing nearest the new below-grade wall. The foundation support systems for the adjacent buildings are not known to us at this time, but in our opinion, are likely to consist of shallow spread footing or mat foundations.

    Retaining wall backfill less than 5 feet deep should be compacted to at least 90 percent relative compaction using light compaction equipment. Backfill greater than 5 feet deep should be entirely compacted to at least 95 percent relative compaction. If heavy compaction equipment is used, the walls should be appropriately designed to withstand loads exerted by the heavy equipment, and/or temporarily braced.

    Retaining walls should be supported on the mat foundation designed in accordance with the recommendations presented previously under Section 6.3.1, Mat Foundation.

    6.5 LATERAL AND UPLIFT LOAD RESISTANCE

    Resistance to lateral loads may be provided by friction along the base of foundations and by passive pressures acting on the sides of foundation. A friction coefficient of 0.35 times the dead load may be used to evaluate the allowable frictional resistance along the bottom of foundation. A passive pressure equal to an equivalent fluid pressure of 350 pcf can be used for lateral load resistance against the sides of footings and below grade walls perpendicular to the direction of loading. To develop this passive pressure, we anticipate deformations of about -inch.

    Resistance to uplift may be developed by the combination of the weight of the structure and the frictional resistance between the exterior faces of walls and the retained soils. Resistance to uplift forces by engaged soil weight may be calculated by assuming an effective soil mass the same width of foundation or slab using effective soil or lean concrete weight of 64 pcf below the water table (15 feet) and 125 pcf above the water table. Frictional resistance within the backfill soil can be calculated as 0.35 times the effective lateral loads acting on the exterior faces of the walls. Additional geotechnical design recommendations can be provided if alternative means of providing uplift resistance are proposed.

    6.6 ADDITIONAL GEOTECHNICAL SERVICES

    Fugro should review geotechnical aspects of the plans and specifications to check for conformance with the intent of our recommendations. The analyses, designs, opinions, and recommendations submitted in this report are based in part upon the data obtained from the subsurface explorations conducted for the Brower Center project, upon the conditions existing when services were conducted, and upon information provided to Fugro by representatives of the City of Berkeley and the RWQCB. Variations of subsurface conditions from those analyzed

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    or characterized in the report are possible, as may become evident during construction. In that event, it may be advisable to revisit certain analyses or assumptions.

    We recommend that Fugro be retained to provide geotechnical services during site grading and foundation installation to observe compliance with the design concepts, specifications and recommendations presented in this report. These services should include consultation during project design and construction for issues related to the handling of groundwater and contaminated soil and groundwater that may be encountered during construction.

    7.0 LIMITATIONS

    Our services consist of professional opinions, conclusions, and recommendations that are made in accordance with generally accepted geotechnical engineering principles and practices. This warranty is in lieu of all other warranties, either expressed or implied.

    The analyses and recommendations contained in this report are based on the data obtained from the subsurface explorations conducted for this study and relevant previous explorations. These explorations indicate subsurface conditions only at specific locations and times, and only to the depths penetrated. Variations may exist and conditions not observed or described in this report could be encountered during construction. Our conclusions and recommendations are based on our analysis of the observed conditions. If conditions other than those described in this report are encountered, we should be notified so that we can provide additional recommendations, if warranted.

    This report has been prepared for the exclusive use of Oxford Street Development, LLC and their consultants for specific application to the Brower Center as described herein. In the event that there are any changes in the ownership, nature, design, or location of the proposed project, or if any future additions are planned, the conclusions and recommendations contained in this report should not be considered valid unless 1) the project changes are reviewed by Fugro, and 2) conclusions and recommendations presented in this report are modified or verified in writing. Reliance on this report by others must be at their risk unless we are consulted on the use or limitations. We cannot be responsible for the impacts of any changes in geotechnical standards, practices, or regulations subsequent to performance of services without our further consultation. We can neither vouch for the accuracy of information supplied by others, nor accept consequences for unconsulted use of segregated portions of this report.

  • PLATES

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    APPENDIX A FIELD EXPLORATIONS

    The field exploration consisted of a surface reconnaissance and a subsurface exploration program. The exploration was conducted using a drill rig equipped with a truck-mounted, hollow stem auger. Four 8inch diameter exploratory borings, designated B-1 through B-4 were drilled between December 29 and 30, 2004, to a maximum depth of 50 feet. Boring B- 1 was converted to a piezometer to measure the groundwater level at the site. The approximate locations of the exploratory borings are shown on the Site Plan, Plate 2. The soils encountered in the borings were continuously logged in the field by our representative. The soils are described in accordance with the Unified Soil Classification System (ASTM D-2487.) Upon completion of our field explorations, the borings were backfilled with neat cement grout. The logs of the borings, as well as a key for the classification of the soil (Plate A-1), are included as part of this appendix.

    Representative soil samples were obtained from the borings using a Modified California split-barrel drive sampler (outside diameter of 3.0 inches, inside diameter of 2.5 inches) and a Standard Penetration Test (SPT) split-barrel drive sampler (outside diameter of 2.0 inches, inside diameter of 1.375 inches). All samples were transmitted to our laboratory for evaluation and appropriate testing. Both sampler types are indicated in the "Sampler" column of the boring logs as designated in Plate A-1.

    Resistance blow counts were obtained with the samplers by dropping a 140-pound hammer through a 30-inch free fall using an automatic hammer system. The sampler was driven 18 inches, or a shorter distance where hard resistance was encountered, and the number of blows were recorded for each 6 inches of penetration. The blows per foot recorded on the boring logs represent the accumulated number of blows that were required to drive the last 12 inches. Due to the use of the automatic hammer system the blow counts are not standard penetration resistance values.

    The elevations indicated on the boring logs were obtained by interpreting the topographic contours on the Topographic Survey, dated June 2003, prepared by Moran Engineering, Inc. Datum is unknown.

    The attached boring logs and related information show our interpretation of the subsurface conditions at the dates and locations indicated, and it is not warranted that they are representative of subsurface conditions at other locations and times.

    Three previous borings were drilled between March 17 and 18, 1998 by Harzaq Engineering Company. Their borings were conducted using a CME 75 drill rig equipped with hollow-stem augers. The logs of Previous Borings PB-1 through PB-3 are included in this appendix. They are designated EB-1 through EB-3 on the boring logs.

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    SUMMARY OF PREVIOUS BORINGS BY OTHERS (HARZA, 1998)

    PB-1Surface Elevation = 188.5 feet

    Depth to Groundwater = 20 feetDepth (feet) Description

    0-1 1 inch AC over 4 inches concrete over 6 inches AB 1-8 CLAY (CL), hard, medium brown, moist, silty, sandy 8-18 SAND (SC), very dense, reddish-brown, moist

    18-30 GRAVEL (GC), very dense, reddish-brown, moist, sandy 30-35 CLAY (CL), hard, gray, wet, silty35-38 SAND (SC), dense, light gray, wet38-70 CLAY (CL), stiff to hard, yellowish-brown, wet, silty

    PB-2Surface Elevation = 188.5 feet

    Depth to Groundwater = 14 feetDepth (feet) Description

    0-0.8 1 inch AC over 9 inches AB0.8-7.5 CLAY (CL), very stiff, reddish-brown, moist, silty 7.5-8.5 SAND (SC), dense, olive-gray, damp to moist 8.5-15 GRAVEL (GC), dense, olive-gray, damp, sandy 15-21 SAND (SC), very dense, yellowish-brown, moist

    21-23.5 SAND (SP/SC), very dense, brown, wet 23.5-30.5 GRAVEL (GC), very dense, yellowish-red, wet 30.5-35 CLAY (CL), hard, gray, wet35-44 SAND (SC), very dense, brownish-yellow, moist 44-71 CLAY (CL), hard, brownish-yellow, damp, silty

    PB-3Surface Elevation = 186.5 feetDepth to Groundwater = 14 feet

    Depth (feet) Description0-0.25 1 inch AC over 2 inches concrete

    0.25-7.5 CLAY (CL), hard, brown, damp, silty 7.5-23.5 GRAVEL (GC), dense to very dense, brown, damp 23.5-26 SILT (ML), hard, brown, moist26-37 CLAY (CL), very stiff to hard, grayish-green, wet, silty 37-70 CLAY (CL), hard, brownish-yellow, moist to wet, silty 44-71 CLAY (CL), hard, brownish-yellow, damp, silty

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    APPENDIX B LABORATORY TESTING PROGRAM

    The laboratory testing program was directed toward a quantitative and qualitative evaluation of the physical and mechanical properties of the soils underlying the site.

    The natural water content was determined on 12 samples of the materials recovered from the borings in accordance with ASTM Test Designation D-2216. These water contents are recorded on the boring logs at the appropriate sample depths.

    Dry density determinations were performed on 11 samples of the subsurface soils to evaluate their physical properties. The results of these tests are shown on the boring logs at the appropriate sample depths.

    Atterberg Limit determinations were performed on two samples of the subsurface soils to determine the range of water content over which these materials exhibit plasticity. The Atterberg Limits were determined in accordance with ASTM Test Designations D-428 and D-424. These values are used to classify the soil in accordance with the Unified Soil Classification System and to indicate the soil's compressibility and expansion potentials. The results of these tests are presented on Plate B-1, and on the logs of the borings at the appropriate sample depths.

    The percent passing the #200 sieve was determined on two samples of the subsurface soils to aid in the classification of these soils. These tests were performed in accordance with ASTM Designation D-1140. The results of these tests are shown on the boring logs at the appropriate sample depths.

    Gradation tests were performed on two samples of the subsurface soils in accordance with California Test Method No. 202. These tests were performed to assist in the classification of the soils and to determine their grain size distribution. The results of these tests are presented on Plate B-2.

    Unconfined compression tests were performed on two undisturbed samples of the clayey subsurface soils to evaluate the undrained shear strengths of these materials. The unconfined tests were performed in accordance with ASTM Test Designation D-2166 on samples having a diameter of 2.4 inches and a height-to-diameter ratio of at least two. Failure was taken as the peak normal stress. The results of these tests are presented on Plate B-3, and on the logs of the borings at the appropriate sample depths.

  • APPENDIX D GUIDE SPECIFICATIONS SITE EARTHWORK

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    APPENDIX D GUIDE SPECIFICATIONS - SITE EARTHWORK

    FOR BROWER CENTER

    BERKELEY, CALIFORNIA

    1.0 GENERAL

    1.1 Scope of Work

    These specifications and applicable plans pertain to and include all site earthwork including, but not limited to, the finishing of all labor, tools, and equipment necessary for site clearing and stripping, disposal of excess materials, excavation, preparation of foundation materials for receiving fill, and placement and compaction of fill to the lines and grades shown on the project grading plans.

    1.2 Performance

    The Contractor warrants all work to be performed and all materials to be furnished under this contract against defects in materials or workmanship for a period of __ year(s) from the date of written acceptance of the entire construction work by the Owner.

    Upon written notice of any defect in materials or workmanship during said __-year period, the Contractor shall, at the option of the Owner, repair or replace said defect and any damage to other work caused by or resulting from such defect without cost to the Owner. This shall not limit any rights of the Owner under the "acceptance and inspection" clause of this contract.

    The Contractor shall be responsible for the satisfactory completion of all site earthwork in accordance with the project plans and specifications. This work shall be observed and tested by a representative of Fugro West, Inc., hereinafter known as the Geotechnical Engineer. Both the Geotechnical Engineer and the Architect/Engineer are the Owner's representatives. If the Contractor should fail to meet the technical or design requirements embodied in this document and on the applicable plans, he shall make the necessary readjustments until all work is deemed satisfactory as determined by the Geotechnical Engineer and the Architect/Engineer. No deviation from the specifications shall be made except upon written approval of the Geotechnical Engineer or Architect/Engineer.

    No site earthwork shall be performed without the physical presence or approval of the Geotechnical Engineer. The Contractor shall notify the Geotechnical Engineer at least twenty-four hours prior to commencement of any aspect of the site earthwork.

    The Geotechnical Engineer shall be the Owner's representative to observe the grading operations during the site preparation work and the placement and compaction of fills. He shall make enough visits to the site to familiarize himself generally with the progress and quality of

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    the work. He shall make a sufficient number of tests and/or observations to enable him to form an opinion regarding the adequacy of the site preparation, the acceptability of the fill material, and the extent to which the compaction of the fill, as placed, meets the specification requirements. Any fill that does not meet the specification requirements shall be removed and/or recompacted until the requirements are satisfied.

    In accordance with generally accepted construction practices, the Contractor shall be solely and completely responsible for working conditions at the job site, including safety of all persons and property during performance of the work. This requirement shall apply continuously and shall not be limited to normal work hours.

    Any construction review of the Contractor's performance conducted by the Geotechnical Engineer is not intended to include review of the adequacy of the Contractor's safety measures in, on or near the construction site.

    Upon completion of the construction work, the Contractor shall certify that all compacted fills and foundations are in place at the correct locations, have the correct dimensions, are plumb, and have been constructed in accordance with sound construction practice. In addition, he shall certify that the materials used are of the types, quantity and quality required by the plans and specifications.

    1.3 Site and Foundation Conditions

    The Contractor is presumed to have visited the site and to have familiarized himself with existing site conditions and the report titled, "Geotechnical Study, Brower Center, Berkeley, California", dated February 23, 2005. The Contractor shall not be relieved of liability under the contract for any loss sustained as a result of any variance between conditions indicated by or deduced from the soil report and the actual conditions encountered during the course of the work.

    The Contractor shall, upon becoming aware of surface and/or subsurface conditions differing from those disclosed by the investigation, promptly notify the Owner as to the nature and extent of the differing conditions, first verbally to permit verification of the conditions, and then in writing. No claim by the Contractor for any conditions differing from those anticipated in the plans and specifications and disclosed by the soil investigation will be allowed unless the Contractor has so notified the Owner, verbally and in writing, as required above, of such changed conditions.

    1.4 Dust Control

    The Contractor shall assume responsibility for the alleviation or prevention of any dust nuisance on or about the site or offsite borrow areas. The Contractor shall assume all liability, including court costs of codefendant, for all claims related to dust or windblown materials attributable to his work.

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    2.0 DEFINITION OF TERMS

    Engineered Fill: All soil or soil-rock material placed onsite in order to raise grades or to backfill excavations, and upon which the Geotechnical Engineer has conducted sufficient tests and/or observations to enable him to issue a written statement that, in his opinion, the fill has been placed and compacted in accordance with the specification requirements.

    Onsite Material: Material obtained from the required site excavations.

    Import Material: Material obtained from offsite borrow areas.

    ASTM Specifications: The American Society for Testing and Materials Standards, latest edition.

    Degree of Compaction: The ratio, expressed as a percentage, of the in-place dry density of the compacted fill material to the maximum dry density of the same material as determined by ASTM Test Designation D1557-91.

    3.0 SITE PREPARATION

    3.1 Clearing and Grubbing

    The contractor shall accept the site in its present condition and shall remove from the area of the designated project earthwork all obstructions including concrete, asphalt pavement, buried foundations, slabs, utility lines, trees and associated root systems, debris and any other matter determined by the Geotechnical Engineer to be deleterious. Such material shall become the property of the Contractor and shall be removed from the site. Holes resulting from the removal of underground obstructions that extend below finish grades shall be cleared and backfilled with structural fill.

    3.2 Stripping

    Where vegetation exists, the site shall be stripped to a minimum depth of 6 inches or to such greater depth as the Geotechnical Engineer in the field may consider as being advisable to remove all surface vegetation and organic laden topsoil. Stripped topsoil with an organic content in excess of 3 percent by volume shall be stockpiled for possible use in landscaped areas or removed from the site.

    4.0 EXCAVATION

    All excavations shall be performed to the lines and grades and within the tolerances specified on the project grading plans. All overexcavation below the grades specified shall be backfilled at the Contractor's expense and shall be compacted in accordance with the specifications. The Contractor shall assume full responsibility for the stability of all temporary construction slopes onsite.

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    5.0 SUBGRADE PREPARATION

    Surfaces to receive compacted fill, and those on which concrete slabs and pavements will be constructed, shall be scarified to a minimum depth of 6 inches and compacted. All ruts, hummocks, or other uneven surface features shall be removed by surface grading prior to placement of any fill materials. All areas to receive fill material shall be approved by the Geotechnical Engineer prior to placement of any fill material.

    6.0 GENERAL REQUIREMENTS FOR FILL MATERIAL

    All fill material shall be approved by the Geotechnical Engineer. The material shall be a soil or soil-rock mixture free from organic matter or other deleterious substances. The fill material shall not contain rocks or rock fragments over 4 inches in greatest dimension and not more than 15 percent shall be over 2 inches in greatest dimension. Onsite material having an organic content of less than 3 percent by volume is suitable for use as fill in all areas except where non-expansive import material is specified. Removed concrete, asphalt concrete, and baserock may be reused as fill, provided they are broken up to meet the aforementioned requirements.

    Non-expansive fill shall be predominantly granular, have an organic content of less than 3 percent by volume, a liquid limit less than 40, and a plasticity index not exceeding 15.

    All imported fill material shall be non-expansive and shall contain no environmental contaminants or debris.

    7.0 PLACING AND COMPACTING FILL MATERIAL

    All structural fill less than 5 feet thick shall be compacted by mechanical means to produce a minimum degree of compaction of 90 percent as determined by ASTM Test Designation D1557-91. All structural fill greater than 5 feet in thickness shall be compacted to at least 95 percent relative compaction. Field density tests shall be performed in accordance with either ASTM Test Designation D1556-82 (Sand-Cone Method) or ASTM Test Designation D2922-81 and D3017-88 (Nuclear Probe Method). The locations and number of field density tests shall be determined by the Geotechnical Engineer. The results of these tests and compliance with these specifications shall be the basis upon which satisfactory completion of work shall be judged by the Geotechnical Engineer.

    8.0 TRENCH BACKFILL

    Pipeline trenches shall be backfilled with compacted structural fill placed in lifts not exceeding 8 inches of uncompacted thickness. If onsite soils are used, the material shall be compacted by mechanical means to a minimum degree of compaction of 90 percent. In all building pad and pavement areas, the upper 3 feet of onsite trench backfill material shall be compacted to a minimum degree of compaction of 95 percent. Imported sand may also be used for backfilling trenches, provided it is compacted to at least 95 percent. If imported sand backfill

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    is used, sufficient water shall be added during the trench backfilling operations to prevent the soil from bulking during compaction.

    9.0 TREATMENT AFTER COMPLETION OF EARTHWORK

    After the earthwork operations have been completed and the Geotechnical Engineer has finished his observation of the work, no further earthwork operations shall be performed except with the approval of and under the observation of the Geotechnical Engineer.

    It shall be the responsibility of the Contractor to prevent erosion of freshly graded areas during construction and until such time as permanent drainage and erosion control measures have been installed.