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TYPE OF SERVICESPreliminary Geotechnical and GeologicHazards InvestigationPROJECT NAMESanta Clara County Civic Center (SC5)Preliminary InvestigationLOCATIONCLIENTPROJECT NUMBERDATE70 West Hedding StreetSan Jose, CaliforniaLowe Enterprises Real Estate Group713-2-1April 4, 2017

Type of ServicesProject NameLocationClientClient AddressProject NumberDatePreliminary Geotechnical and GeologicHazards InvestigationSanta Clara County Civic Center (SC5)Preliminary Investigation70 West Hedding StreetSan Jose, CaliforniaLowe Enterprises Real Estate Group595 Market Street, Suite 2550San Francisco, California713-2-1April 4, 2017Prepared byPaul K. Mateo, P.E.Project EngineerGeotechnical Project ManagerPrepared byCraig Harwood, C.E.G.Project Engineering GeologistC. Barry Butler, P.E., G.E.Senior Principal EngineerQuality Assurance Reviewer

TABLE OF CONTENTSSECTION 1: INTRODUCTION . 11.1Project Description -------------------------------------- 11.2Scope of Services ---------------------------------------- 21.3Exploration Program ------------------------------------ 21.4Laboratory Testing Program -------------------------- 21.5Corrosion Screening ------------------------------------ 21.6Environmental Services -------------------------------- 2SECTION 2: REGIONAL SETTING . 32.1Geological Setting --------------------------------------- 32.1.1 Regional Geologic Setting. 32.2Regional Seismicity ------------------------------------- 3Table 1: Approximate Fault Distances . 42.3Historical Earthquakes --------------------------------- 42.4Maximum Past Ground Shaking --------------------- 5SECTION 3: SITE CONDITIONS . 63.1Recent Site History and Air Photo Review ------- 63.2Surface Description ------------------------------------- 63.3Site Geology and Subsurface Conditions -------- 73.3.1 Plasticity/Expansion Potential . 83.3.2 In-Situ Moisture Contents . 83.3.2 Sulfate Contents . 83.4Ground Water ---------------------------------------------- 83.5Corrosion Screening ------------------------------------ 9Table 2: Summary of Corrosion Test Results . 93.5.1 Preliminary Soil Corrosion Screening . 9SANTA CLARA COUNTY CIVIC CENTER(SC5) PRELIMINARY INVESTIGATION713-2-1Page i

SECTION 4: GEOLOGIC HAZARDS .104.1Fault Surface ---------------------------------------- 104.2Estimated Ground Shaking ------------------------- 104.3Liquefaction ------------------------------------------ 104.3.1 Background .114.3.2 Analysis .114.3.3 Summary .124.3.4 Ground Rupture Potential .124.4Lateral Spreading -------------------------------------- 124.5Seismic Settlement/Unsaturated Sand Shaking ------------------------------------------------ 134.6Landsliding ----------------------------------------------- 134.7Tsunami/Seiche ----------------------------------------- 134.8Flooding - 134.9Naturally Occurring Asbestos ---------------------- 14SECTION 5: CONCLUSIONS .145.1Summary -------------------------------------------------- 145.1.1 Strong Ground Shaking.155.1.2 Potential for Minor Liquefaction-Induced Settlements.155.1.3 Potential for Significant Static Settlements for Taller Structures.155.1.4 Shallow Ground Water.155.1.5 Presence of Undocumented Fill .165.1.6 Presence of Moderately to Highly Expansive Soils .165.1.7 Previous Site Development and Future Re-Development .165.1.8 Soil Corrosion Potential .165.2Design-Level Geotechnical -------------------- 17SECTION 6: EARTHWORK .176.1Anticipated Earthwork -------------------------- 17SECTION 7: POTENTIAL FOUNDATIONS ALTERNATIVES .187.1Summary of Recommendations ------------------- 187.2Seismic Design Criteria ------------------------------ 18Table 3: CBC Site Categorization and Site Coefficients .19SANTA CLARA COUNTY CIVIC CENTER(SC5) PRELIMINARY INVESTIGATION713-2-1Page ii

7.3Shallow Foundations ---------------------------------- 197.3.1 Spread Footings.197.3.2 Footing Settlement .197.3.3 Mat Foundation over Ground Improvement .207.4Deep ------------------------------------------------- 20SECTION 8: CONCRETE SLABS AND PEDESTRIAN PAVEMENTS .208.1Interior Slabs-on-Grade ------------------------------ 208.2Exterior Flatwork --------------------------------------- 20SECTION 9: VEHICULAR PAVEMENTS .219.1Asphalt Concrete --------------------------------------- 21Table 4: Asphalt Concrete Pavement Recommendations, Design R-value 5 .21SECTION 10: LIMITATIONS .21SECTION 11: REFERENCES .23FIGURE 1: VICINITY MAPFIGURE 2: SITE PLANFIGURE 3: REGIONAL FAULT MAPFIGURE 4: VICINITY GEOLOGIC MAPFIGURE 5: HISTORICAL EARTHQUAKES MAPFIGURE 6A TO 6E: LIQUEFACTION ANALYSIS SUMMARY – CPT-01 TO CPT-05APPENDIX A: FIELD INVESTIGATIONAPPENDIX B: LABORATORY TEST PROGRAMAPPENDIX C: LIQUEFACTION ANALYSES CALCULATIONSSANTA CLARA COUNTY CIVIC CENTER(SC5) PRELIMINARY INVESTIGATION713-2-1Page iii

Type of ServicesProject NameLocationPreliminary Geotechnical and Geologic Hazards InvestigationSanta Clara County Civic Center (SC5) Preliminary Investigation70 West Hedding StreetSan Jose, CaliforniaSECTION 1: INTRODUCTIONThis preliminary geotechnical report was prepared for the sole use of Lowe Enterprises RealEstate Group for the Santa Clara County Civic Center (SC5) Preliminary Investigation in SanJose, California. The location of the site is shown on the Vicinity Map, Figure 1.The purpose of this investigation was to evaluate the existing subsurface conditions of the entiresite and develop an opinion regarding potential geotechnical concerns that could impact theproposed development. The preliminary geotechnical recommendations contained in this reportare for your forward planning, cost estimating, and preliminary project design. For our use, wewere provided with the following document: A presentation titled, “Santa Clara County Civic Center Master Plan,” prepared byLowe Gensler, dated November 30, 2016. A Request For Proposal (RFP) titled, “Santa Clara County Civic Center Campus (SC5),Consultant Request for Proposal,” prepared by Lowe Enterprises Real Estate Group,dated August 19, 2016.A design-level investigation and report for Site A (Richey Site) and a portion of Site C (Lot-C) isforthcoming.1.1PROJECT DESCRIPTIONWe understand that the 55-acre Santa Clara County Civic Center will undergo multi-phasedplanning and development, which will include government buildings, parking, and open spaces.Based on the provided information, the planning for public space on the Civic Center Campus isabout 1.15 million square feet in a study area of 40 acres; twenty-three acres will be for publicuses, and the other 17 acres will be considered for revenue-generating purposes. Structureswill have a height limit of 150 feet on the eastern portion, and 50 feet on the western portion,due to the site’s proximity to San Jose International airport. The structures will be of eitherSANTA CLARA COUNTY CIVIC CENTER(SC5) PRELIMINARY INVESTIGATION713-2-1Page 1

wood, steel, or concrete construction. Appurtenant parking, utilities, landscaping and otherimprovements necessary for site development are also planned.1.2SCOPE OF SERVICESOur scope of services was presented in our proposal dated August 29, 2016 (revised onSeptember 12, 2016) and consisted of field and laboratory programs to evaluate physical andengineering properties of the subsurface soils, engineering analysis to prepare preliminaryrecommendations for site work and grading, building foundations, flatwork, retaining walls, andpavements, and preparation of this report. Brief descriptions of our exploration and laboratoryprograms are presented below.1.3EXPLORATION PROGRAMField exploration consisted of four borings drilled on November 17, 216 with truck-mounted,hollow-stem auger drilling equipment and five Cone Penetration Tests (CPTs) advanced onNovember 15, 2016. The borings were drilled to depths of 4½ to 40 feet; the CPTs wereadvanced to depths of approximately 45 to 72 feet. Seismic shear wave velocity measurementswere collected from CPT-2. Three of the borings (Borings EB-2, EB-3, and EB-4) wereadvanced adjacent to CPTs (CPT-3, CPT-4, and CPT-2, respectively) for direct evaluation ofphysical samples to correlated soil behavior.The borings and CPTs were backfilled with cement grout in accordance with local requirements;exploration permits were obtained as required by local jurisdictions. The approximate locationsof our exploratory borings are shown on the Site Plan, Figure 2. Details regarding our fieldprogram are included in Appendix A.1.4LABORATORY TESTING PROGRAMIn addition to visual classification of samples, the laboratory program focused on obtaining datafor foundation design and seismic ground deformation estimates. Testing included moisturecontents, dry densities, washed sieve analyses, Plasticity Index tests, and triaxial compressiontests. Details regarding our laboratory program are included in Appendix B.1.5CORROSION SCREENINGTwo samples from our borings from depths of 1½ and 3½ feet were tested for saturatedresistivity, pH, and soluble sulfates and chlorides. In general, the on-site soils can becharacterized as severely corrosive to buried metal, and non-corrosive to buried concrete.1.6ENVIRONMENTAL SERVICESEnvironmental services were not requested for this project. If environmental concerns aredetermined to be present during future evaluations, the project environmental consultant shouldreview our geotechnical recommendations for compatibility with the environmental concerns.SANTA CLARA COUNTY CIVIC CENTER(SC5) PRELIMINARY INVESTIGATION713-2-1Page 2

SECTION 2: REGIONAL SETTING2.1GEOLOGICAL SETTING2.1.1Regional Geologic SettingThe site is located in an area where the south bay alluvial plain abuts the northeast portion ofthe Santa Cruz Mountains. These mountains represent one mountain range in a series ofnorthwesterly-aligned mountains forming the Coast Ranges geomorphic province of Californiathat stretches from the Oregon border nearly to Point Conception. In the San Francisco Bayarea, most of the Coast Ranges has developed on a basement of tectonically mixedCretaceous- and Jurassic-age (70- to 200-million years old) rocks of the Franciscan Complex.Younger sedimentary and volcanic units locally cap these basement rocks. Still youngersurficial deposits that reflect geologic conditions of the last million years or so cover most of theCoast Ranges.Movement on the many splays of the San Andreas Fault system has produced the dominantnorthwest-oriented structural and topographic trend seen throughout the Coast Ranges today.This trend reflects the boundary between two of the Earth's major tectonic plates: the NorthAmerican plate to the east and the Pacific plate to the west. The San Andreas Fault system andits major branching faults is about 40 miles wide in the Bay area and extends from the SanGregorio Fault near the coastline to the Coast Ranges-Central Valley blind thrust at the westernedge of the Great Central Valley as shown on the Regional Fault Map, Figure 3. The SanAndreas Fault is the dominant structure in the system, nearly spanning the length of California,and capable of producing the highest magnitude earthquakes. Within the region, the SanAndreas Fault system, which distributes shearing across a complex assemblage of primarilyright lateral, strike-slip, parallel and sub-parallel faults that includes the Hayward and Calaverasfaults. The western traces of a segment of the Calaveras Fault occur within the San JoseFoothills in the northeastern corner of the quadrangle. The Hayward Fault is farther west, nearthe base of the San Jose Foothills. The northwest-trending Silver Creek thrust fault bisects theSilver Creek Hills in the southeastern part of the quadrangle and is projected beneath the valleyfill alluvium in a northerly direction toward the vicinity of Fremont. Several smaller transpressivefaults also are mapped within the quadrangle, primarily along the base of the San JoseFoothills. They include the Evergreen, Quimby, Piercy, and Clayton faults.2.2REGIONAL SEISMICITYThe San Francisco Bay area is one of the most seismically active areas in the country. Whileseismologists cannot predict earthquake events, geologists from the U.S. Geological Surveyhave recently updated earlier estimates from their Uniform California Earthquake RuptureForecast (Version 3) publication. The estimated probability of one or more magnitude 6.7earthquakes (the size of the destructive 1994 Northridge earthquake) expected to occursomewhere in the San Francisco Bay Area has been revised (increased) from 63 percent to 72percent for the period 2014 to 2043 (Aagaard et al., 2016). The faults in the region with thehighest estimated probability of generating damaging earthquakes in this time interval are theHayward (33 percent), Rodgers Creek (33 percent), Calaveras (26 percent), and San AndreasSANTA CLARA COUNTY CIVIC CENTER(SC5) PRELIMINARY INVESTIGATION713-2-1Page 3

Faults (22 percent). In this 30-year period, the probability of an earthquake of magnitude 6.7 orlarger occurring is 22 percent along the San Andreas Fault and 33 percent for the Hayward orRodgers Creek Faults.During such a major earthquake, ground rupture at the site is not anticipated, but very strongground shaking would likely occur.Faults considered capable of generating significant earthquakes are generally associated withthe well-defined areas of crustal movement, which trend northwesterly. Table 1 presents thefaults considered by the state to be active within a 25 kilometer (about 15 mile) radius of theproject.Local faults are indicated on the Regional Fault Map, Figure 3, illustrating the distances of thesite to significant fault zones.Table 1: Approximate Fault DistancesDistanceFault Name(miles)(kilometers)Hayward (Southeast Extension)5.48.7Monte Vista-Shannon8.012.9Hayward (Total Length)8.313.3Calaveras10.917.5San Andreas (1906)12.219.7Sargent14.924.0A regional fault map is presented as Figure 3, illustrating the relative distances of the site tosignificant fault zones.2.3HISTORICAL EARTHQUAKESWe reviewed and performed a data search of known historical earthquakes of magnitude 5 orgreater within a 100-kilometer radius of the site using available published data from theCalifornia Division of Mines and Geology (CDMG) computerized earthquake catalog of eventsthrough December 1999. Figure 5 shows the epicenters of these magnitude 5 or greaterevents. We also included data from Townley and Allen (1939) and the U.S. Geological SurveyEarthquake Data Base System, giving 200 years of data in the search area.Several relatively large magnitude earthquakes have occurred in the region during the abovenoted time period, including the Loma Prieta Earthquake of 1989 that was centeredapproximately 35 miles south of the site. Figure 5, adopted from Toppozada & Others (2000)illustrates these historical earthquakes.SANTA CLARA COUNTY CIVIC CENTER(SC5) PRELIMINARY INVESTIGATION713-2-1Page 4

2.4MAXIMUM PAST GROUND SHAKINGDue largely to the sparse nature of the population in the area at the time, very few observationsof the 1868 Hayward earthquake record specific evidence for liquefaction in the south bay arearegion. Lawson (1908) reports a story from a survivor of the 1868 earthquake, Mrs. N.Ainsworth, in which she states by second hand information that “water spurted up in the streetsof San Jose, and out in the road between Milpitas and San Jose, to the height of several feet.”As a result of the 1906 earthquake, the investigation of Lawson (Lawson et al., 1908) was thefirst to survey damage over the entire felt

recommendations for site work and grading, building foundations, flatwork, retaining walls, and pavements, and preparation of this report. Brief descriptions of our exploration and laboratory programs are presented below. 1.3 EXPLORATION PROGRAM . Field exploration consisted of four borings drilled on November 17, 216 with truck-mounted,